ABSTRACTS - Oxford Academic

ABSTRACTS

Pages 2A to 131A contain the abstracts that have been submitted forpresentation during the 1994 ASZ Annual Meeting. All abstracts arelisted in numerical order according to the abstract number assigned toeach presentation. All abstract numbers are cross referenced with thedaily author presentation title block, author index, and keyword index.

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Parasitic Effects On Host Hormones and Behavior

10 12PARASITISM-INDUCED REPROCRAMMING OF IIOSTINSECT DEVELOPMENT AND METAMORPHOSIS.N.E. Bcckagc, University of California-Riverside,Riverside. CA 92521-0314.

Endoparasilic insects cause niajor alterations in hostgrowth, development, and metamorphosis that arcsymptomatic of disruptive effects on the host's nervous andendocrine systems. Feeding inhibition or anorexiafrequently occurs, although how the nervous systemmediates these effects is not known. In tobacco homwormlarvae parasitized by Colcsia conf>rcgata. the host stopsfeeding before the wasps emerge. Many other parasitizedinsects show a similar cessation of host food consumption.Melamorphic arrest also is common, though the stage atwhich arrest occurs is variable and correlated with thespecies of parasitoid attacking the host. Most casesinvolve endocrine dysfunction, and the classes of hormonesaffected include the juvenile hormones, ccdystcroids, andncuropcplidcs. The cn/.ymcs involved in their regulation ordegradation may also be affected. An excellent example isjuvenile hormone cslcrasc, which is inhibited inhomworms parasitized by C. congre%ala. thus inhibitingmetamorphosis. In contrast, levels of* Ihi* cn/ymc increaseprecociously to high levels in species parasitized bychcloninc wasps, thus triggering precociousmetamorphosis. Effects on the synthesis, processing,and/or release of hormones or ncurohormoncs may also beinvoked. Metamorphosis is inhibited in parasitizedhornworms due to die accumulation of neuropeptides,including PTTH. in the brain-CC-CA complex of the hostlarva. Lack of release of PTTH accounts for ccdystcroiddeficiency, and explains why hosts with emerged wasps failto molt. Developmental paralysis is induced by severaldifferent mechanisms. A survey of parasitized speciesreveals thai the absence of endocrine effects of parasitismupon die host appears to be rare, at least among insectsThe same may lie true for vertebrates, though the effectsmay be mote difficult to decipher. Supported by NSF IBN-9006003 and USDA 92-37302-7470.

PRODUCTION OF A HUMAN GROWTHH O R M O N E - L I K E F A C T O R BYSPIROMETRA. Pharcs, C.K., University ofNebraska Medical Center, Omaha, Nebraska.Plcroccrcoids of the tapeworm S. mansonoidesarc tissue invading larvae which arc able toinfect individuals from all vertebrate classesexcept fish. Laboratory rodents respond toplerocercoid infections as if they were beingtreated daily with exogenous growth hormone(GH). Plerocercoid growth factor (PGF)mimics the growth promoting actions ofmammalian Gils in general, but mostinterestingly is able to produce biologicalresponses thought to be unique to humanGH(hGH) as well. Unique hGH actions sharedby PGF include: lactogenic effects, activity inprimates and broad growth promoting ability.The significance of PGF in the evolution andsurvival of Spiromelra is a matter ofspeculation, however, the biological results ofthe expression of PGF in experimental hosts istruly phenomenal.

13Results obtained with the model combina-tion Trichobitharzia ocellata-LymnaeastagnaZis have shown that the physiologi-cal effects evoked by schistosomes intheir snail host are caused by theirinterference with the Ncuro-EndocrineSystem (NES) involved. An identifiedpeptide schiobosomin has appeared to playa crucial role in establishing theseeffects on reproduction and growth. Thisfactor originates from haemocytes and aconnective tissue cell type and meets thecriteria of being a cytokine. Experimentshave shown that it is also released innon-parasitized snails during "stress".Therefore schistosomin can be comparedwith 111 released by macrophages instressed mammals. So the effects of schis-tosomes on the NES of their snail host aremediated by factor(s) from the Immunesystem. Apparently parasites can beconsidered as chronical stressors.

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The Biology, Ecology and Physiology Of Zebra Mussels

17 22GENETICS OF THE ZEBRA MUSSEL. DREISSENAl'OLYMORPIIA, AND RELATED TAXA.Marsdcn, J. E.*, A. Spidlc, and B. May. Illinois NaturalHistory Survey. Zion, and Cornell University, llliaca.Several studies of the population genetics of zebramussels in North America and Europe have shown that(1) zebra mussels have very high levels of geneticvariabilily as detected by protein elcclrophoresis, (2) theinvasion of zebra mussels into North American consistedof a large number of individuals, likely from more thanone donor population, (3) genetic differentiation ofsubpopulalions has not yet occurred in North America,and (4) the population of zebra mussels in lakes Eric andOnlaiio comprises two species, Dreissena polymorphaand D. bugeiisis (quagga mussel). Considerablemorphological and color pattern variation occurs in bothspecies; most notably, the quagga mussel has a shallow-water, dark morph found on hard substrates and a deep-water, pale morph which is found in soft sediments. Dataon moiphological variation and color morph frequencyamong populations and between continents lias revealedconsiderable morphological plasticity, but as yet nocorrelations between morphological variation andecological conditions have been found. The high levelsof variability in the zebra mussel may be a significantfactor in its ability to readily colonize new areas andadapt to a wide range of ecological conditions.

PHYSIOLOGICAL ASPECTS OF ZEBRA MUSSELREPRODUCTION: N EU ROHORMONES.PHEROMONES.SPAWNINGANDFERTIL1ZATION.J.L. Ram*. P.P. Fong. and D. Garton. Wayne SlateUniv.. Deiroit, MI and Indiana Uhiv. at Kokomo.

Fertilization in zebra mussels occurs externally, fol-lowing broadcast spawning of gametes by males and fe-males. Fertilization is promoted by simultaneous spawn-ing of males and females and by mechanisms that facili-tate sperm-egg interaction (sperm motility. chemoattract-ants, and binding). The sludy of gamete maturation andfertilization mechanisms hasr been facilitated byavailability of mussels, reliable methods of releasingcom|x:teni gametes, and the clear cytoplasm of oocytes.External application of serotonin (a neurohormone/trans-mitter) triggers spawning, a method used 10 producelarge numbers of gametes for studies of speim motility,chemoattractants, and fertilization mechanisms.Serotonin probably regulates spawning internally:serotonin causes spawning when injected into either sex,triggers oocyte maturation in ovarian preparations mvitro, and is present in male and female gonads byimmunohistology and HPLC. In the field, activation ofspawning involves environmental factors, with animalsin smaller, faster warming lakes spawning earlier indistinct cohorts than in large lake or riverine habitats.Temperature is a factor; however, chemicals released byphytoplankton or other spawning animals may also playa role. Acclimation to adverse spawning conditions(high temperature, salinity) may enable reproduction inenvironments previously thought to be inaccessible tozebra mussels, (supported by Sea Grants to JLR & DG).

24 25OSMOTIC AND IONIC REGULATION OF NORTHAMERICAN ZEBRA MUSSELS (Dreissenapolvmorpha).T.H. Dietz*, S. Wilcox, H. Silverman andJ.W. Lynn. Louisiana State Univ., BatonRouge.

Dreissena is unique among thefreshwater bivalves being incapable ofsurviving in deionized water or waterdeficient in Mg, Na, K or Cl. The zebramussel experiences rapid loss of ionswhen exposed to specific ion-freesolutions. In addition, Dreissenarapidly accumulates ions whentransferred to solutions containingelevated ion concentrations. For zebramussels to survive hyperosmoticenvironments, the ionic composition mustbe balanced with Na salts present foraccumulation in the blood and Kavailable for redistribution to thecells. A balanced salt solutionapproximating dilutions of seawater aretolerated by zebra mussels if the acuteosmotic challenge does not exceed 100mosra. The mussels adjust to the osmoticchallenge within 8-12 h but requireseveral days to complete acclimation.The rapid ionic and osmotic adjustmentsare likely due to an exceptional rate ofpassive movement and transport.Supported by HSF 90-17461.

GILL STRUCTURE IN ZEBRA MUSSELS:BACTERIAL-SIZED PARTICLE FILTRATION.H. Silverman*, J.W. Lynn, E. Achberger,and T.H. Dietz. Louisiana State Univ.,Baton Rouge.

Filtration of food particles bybivalve gills is somewhat controversial.Our observation of cirri structure andmovement using laser confocal microscopymethods indicate that these structuresform and function as particle trapscapable of capturing items on the orderof 0.5 im in size. The structure of thegill suggests that Dreissena polvmorphais capable of utilizing bacteria as afood source. Radio-label tracerexperiments indicate that a 1 g D.polvmorpha will readily filter bacteriafrom the water column with a t}/2 °f 13

rain for particle clearance from 20 ml ofwater containing 3 x 108 E. coll.Radio-label is incorporated in the TCA-precipitable fraction of whole bodymacromolecules, even after a 48 h chasefollowing the 30 min exposure to S-35labelled E. coli. No pseudofeces wereproduced during the first 90 min afterthe introduction of 107 bacteria/ml.The implications of fitration structureand nutrient uptake are the major focusof this review. (Supported by Sea GrantR/ZM-1-PD and HSF-DCB90-17461).

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Comparative Endocrinology

33 34NASOHYPOPHYSIAL FACTOR, A NOVELHOMODIMERIC GLYCOPROTEIN FROM THELAMPREY PITUITARY.S.A. Sower, A. Takahashi, M. Nozaki, H. Kawauchiand A. Gorbman . University of New Hampshire,Kitasalo University, Kyoto University and Universityof Washington.

During an effort to isolate a gonadotropin fromextracts of lamprey (Pciromyzon marinus) pituitarics, ahomodimcric glycoprotcin was purified and scqucnccd.Us amino acid sequence is not homologous with anyknown pituitary protein. The monomer contains 121amino acids. In the adult it is found abundant in cellsof the rostral pars distalis. In ammococtc larvae it isfound in the olfactory epithelium (hence, the namenasohypophysial factor, NHF) and the adjacenticlcnccphalon, as well as the nasohypophysial duct andentire adenohypophysis. There is as yet no informationconcerning its functional properties. NIIF is the fourthpeptide that has been found in the embryonic olfactoryorgan, and later in the hypolhalamus and/or theadcnoliypopliysis. The ollicrs aic ACTH, somaioslatinand GnRII. Some of the evolutionary aspects of thesefindings will be discussed.

CONADOTROPIN-RELEASING HORMONES INLAMPREYS AND HAGFISH.S.A. Sower. University of New Hampshire, Durham.

This paper summarizes the recent studies in mylaboratory on the structure and function oflamprcyGnRII in sea lampreys, Pciromyzon marinus andAtlantic hagfish, Myxinc glutinosa. The primarystructure orgonadotropin-rcleasing hormonc-III(lamprey GnRH-III) has been determined in sealampreys (Sower ctal., 1993). In immunocylo-chemistry studies, both lamprey GnRH-I and lampreyGnRII-III immunorcaclion were found in the cellbodies in the rosiral hypolhalamus and prcoplic area inlarval and adult sea lamprey (Tobct el al., in press;Nozaki ct al., unpublished). Based on theseimmunocyiochcmical studies and current studies on thebiological activity oflamprcy GnRII-III in adult femaleand male lampreys and the occurrence of this pcplidcduring metamorphosis in lampreys, we suggest thaiboth lamprey GnRH-I and -III arc ncurohormoncsinvolved in reproduction in lampreys. In Atlantichagfish, chromalographic and immunocyiochcmicalevidence showed that the brain contains agonadotropin-releasing hormone (GnRH)-likc moleculethai is closely related to lamprey GnRII-III. Thesestudies indicate that, contrary to earlier reports, hagfishdo have a GnRH-likc molecule thai is more closelyrelated, in terms of immunological detenninanls, tolamprey GnRH-III than to other currently knownvertebrate GnRII molecules. (Supported by NSF DCB-8904919 and 1BN-9022834 to SAS.)

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SEQUENCE OF A POMC cDNA CLONEFROM LAMPREY PITUITARYJ.A. Heinig*, F.W. Kcclcy and J.H. Youson.Research Institute, Hospital for Sick Children,Toronto, and Department of Anatomy and CellBiology, University of Toronto.

A cDNA for proopiomelanocortin (POMC) wasisolated and characterized from a lamprey(Petromyzon marinus) pituitary cDNA library. Toour knowledge this is the first adenohypophysialhormone to be cloned and sequenced from thisrepresentative of the most primitive knownvertebrate. This cDNA contains an open readingframe of 831 bp that predicts a 277 amino acidPOMC protein which demonstrates featuressimilar to POMCs from other species. Inparticular, dibasic cleavage sites, as well as theconsensus sequence for a-melanocyte stimulatinghormone (a-MSH) and p-endorphin, have beenpreserved. However, the sequence correspondingto y-MSH in other species is not present in thiscDNA clone, and the p-MSH sequence ismodified in such a way that it may not code for anactive protein. Northern blot analysis showed lowbut detectable expression levels of this lampreypituitary POMC in larval animals and strongexpression in adult and spawning animals. Atearly stages of metamorphosis expression of thisPOMC was undetectable. These data suggest thatPOMC may play a role in the processes ofdevelopment in the lamprey. Funded by NSERC.

MOLECULAR EVOLUTION OF VASOACTiVEINTESTINAL POLYPEPTIDE (VIP)J.M. ConlorT, Y. Wang, N. Chartreland H. Vaudry. Creighton Univ.Omaha and Univ. of Rouen, France.

Our knowledge of thestructure and activity of multi-functional regulatory peptideVIP in non-mammalian vertebratesis fragmentary. VIP has beenpurified by HPLC from extractsof gastrointestinal tissue froman amphibian, Rana ridibunda(green frog), teleost, Oncor-hynchus mykiss (trout) andholostean, Amia calva (bowfin).The primary structures of thepeptides have been determined.Frog VIP is identical tochicken/alligator VIP anddiffers in amino acid sequencefrom trout/bowfin VIP by asingle substitution (Val5 •* lie) .Synthetic frog VIP produced adose-dependent increase in cAMPin isolated frog anteriorpituitary fragments but thepeptide was 10-fold less potentthan frog PACAP. The data showthat the structure of VIP hasbeen very strongly conservedduring vertebrate evolution.


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37 38Are the Holostei a natural group? Ananalysis based on Heopterygii GHsequences.D.A. Rubin* and R.M. Dores. Universityof Denver.

Classical ichthyology has reliedmainly on morphological measurements toinfer the relationships of fishes.Since the introduction of moleculartechniques, many of the relationshipswithin the Actinopterygii (Chondrosteiand Neopterygii) have been tested todetermine if the morphological andmolecular phylogenies produced arecongruent. For example, the Neopterygii(gar, Ginglymodi; bowfin, Halecomorphi;and the Teleostei) contain two groups(gars and bowfins) which were onceconsidered members of the "Holostei".The Holostei, as presently defined, isnot considered a natural group and,therefore, the derivation of theteleosts is unresolved. In an attemptto resolve the relationships within theNeopterygii, growth hormone (GH) cDNAclones were obtained from thepituitaries of the bowfin (Amia calva,amGH) and gar (Lepisosteus osseus,lepGH). GH amino acid (aa) sequencesfrom amGH and lepGH were comparedphylogenetically with two teleost groups(Ostariophysi and Percomorpha) to revealthat the "holosteans" are more closelyrelated to each other than either is tothe teleosts and, therefore, theHolostei and Teleostei are sister-groupswithin the Neopterygii.

OBTAINING PHYLOGENETICINFORMATION FROM "SPACER"REGIONS IN POLYPEPTIDE HORMONEPRECURSORS.R.M. Dores* and D.A. Rubin.U n i v e r s i t y of Denver

Although t h e r e has beenconsiderable interest in theevolution of the GnRH family ofpeptides, the high degree ofsequence conservation among theGnRHs render these polypeptidesunsuitable for c l ad i s t i canalysis. However, when thesequences of cichlid Pro-GnRHI,frog Pro-GnRIII, rat Pro-GnRHI,mouse Pro-GnRHI, and human Pro-GnRHI were evaluated using amaximum parsimony analysisalgorithm (PAUP 3 . 0 ) , areasonable phylogenetic tree wasgenerated. These results indicatethat phylogenetic information maybe present in the spacer regionsof some polypeptide hormoneprecursors. In addition,cladistic analysis of Pro-insulinand Pro-IGF will also bediscussed. Supported by NSF grant9104707.

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SEX DIFFERENCES IN INACTIVEMETABOLISM: IMPLICATIONS FORSEXUAL SIZE DIMORPHISM.Steven J. Beaupre, Arizona State UniversityWest.

In central Arizona, the western diamondbackrattlesnake (Crotalus alrox) is sexuallydimorphic in size, with males larger thanfemales. I am investigating the proximatecauses of sex differences in growth usingcomparative studies of energetics. Differencesbetween sexes in resting or inactive metabolicexpenditure may contribute directly to sexdifferences in energy available for growth Iquantified oxygen consumption rates of 28inactive snakes using a flow through oxygenanalysis system. Oxygen consumption rateswere measured in response to body size(neonates to large adults), temperature (15° -35°C), time of day, and gender Metabolicrates of western diamondbacks were similar tothose reported for other rattlesnakes.Repeated measures analysis indicatedsignificant effects of all factors investigated.Implications of sex differences in inactivemetabolic expenditure arc discussed.

COVARIATION OF REPRODUCTIVETRAITS IN LACERTID LIZARDS: ACOMPARATIVE STUDY.R. Di'az-Uriarte* and D. Bauwens and L. J.Barbadillo. Univ. Wisconsin-Madison, Inst.Nature Conservation, Belgium, Univ.Autonoma Madrid, Spain. Introduction by T.Garland, Jr.

We analyzed interspecific differences inreproductive traits in lacertid lizards usingFelsenstein's (1985) method of phylogeneti-cally independent contrasts. All traits exhibitstrong positive correlations with female bodysize. Size at maturity and maximum size offemales are isometrically related to meanfemale size, so lizards mature at a constantproportion of their maximum body size. Therelation of total clutch mass to female size isisometric. The partitioning of energy allo-cated to a clutch changes with female size:large species produce more and smalleryoung than expected from a model of geo-metric similarity. After removing the effect ofbody size, all patterns of covariation amongtraits disappear, except for the trade-off sizevs. number of offspring. Thus, female sizeseems to be the single most important factorexplaining the interspecific variation in re-productive traits of lacertids.

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SEASONAL ECOPHYSIOLOGY OF THEFRILLNECK LIZARD, CHLANYDOSAUHUSKINGII, IN TROPICAL AUSTRALIA.K.A. C h r i s t i a n * , A.D. G r i f f i t h s ,and G.S. Bedford. NorthernTerritory University, DarwinAustralia.

Field metabolic rates(FMR) offrillneck lizards were measured atthree times of the year, and bodytemperatures (Tb), activity andmicroclimatic data ,were measuredsimultaneously. FMRs during thedry season were only.25% of thewet season FMRs despite similarthermal conditions during the day.Midday Tbs were more than 4 Ccooler during the dry seasonalthough biophysical models showedseasonal changes in standardmetabolic rates and set-point Tbs.Low FMRs in the dry season areachieved by metabolic depression,thermoregulation at lower Tbs andreduced act ivi ty. However, thelizards were not completely inact-ive and they consumed about 70% asmuch food in the dry as in thewet season.

PROXIMATE CAUSES OF SEXUAL DIMORPHISMIN THE IGUANID LIZARD MICR0L0PHUS(TROPIDURUS) OCCIPITALIS.

G.G.Watkins, Department of BiologyUnivers i ty of Pennsylvania , Ph i l ade lph ia

I examined the w l t h i n - g e n e r a t i o n devel-opmental and demographic processes thatlead to sexual dimorphism in the l i z a r dMicrolophus ocelpitalls. I studied amarked population of these lizards inwestern Ecuador between 1990 and 1994.Sex differences in adult size, shape,and coloration in this species were duein the main to sexual differences ingrowth and development. However, demo-graphic differences between males andfemales also contribute to sexual dim-orphism. The proximate processes lead-ing to sexual dimorphism must be thor-oughly investigated before the selectiveprocesses responsible for the evolutionof sexual dimorphism may be elucidated.

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AN EVALUATION OF HEATED TAX1DERMICMOUNTS AS OPERATIVE ENVIRONMENTALTEMPERATURE SENSORS.G. S. Bakkcn. Indiana State University, TcrreHaute.

Forcndolhcrmic species, standard operativetemperature. '/ '„, can be used to characterize andmap complex thermal environments because it is asingle-number index of thermoregulalory energydemand which can be measured at many pointsusing a heated model of the organism. Healedtaxidcrrnic mounts have been used for this purpose,with the explicit, little-tested assumption that suchmodels duplicate the thermal properties of theorganism because the same fur or feather insulationis present. In the same chambers, I compared thenet metabolic heal production of 3 species of livebirds (Carduclis irislis, ./unco hycmali.s, and Anu.splatyrhynchos) with the electrical power needed tomaintain heated mounts of the same species atnormal body temperature. Calibration plots showgood lo poor agreement which cannot be easilypredicted from animal or model properties. Thus,it appears essential lo calibrate heated laxidcrmicmounts before use as TCK sensor, and so they mayhave few advantages over more easily constructedthermal models of the animal of interest.

EFFECTS OF COMPETITION ANDPREDATION ON THE POPULATIONSTRUCTURE OF LARVAL REDSALAMANDERS (PSEUDOTRITON RUBER).S. M. Welter * and J. E. Fauth. Univ. ofKentucky, Lexington and College of Charleston.

In a field experiment we tested for competitionusing a 2 X 2 X 4 experiment where treatmentswere all combinations of larval density (6 or 12individuals/m^) crossed with food level. Growthwas density-independent at ambient food levels,but when food was added, individuals at lowdensity grew more than those at high density.Larvae sustained non-lethal damage in alltreatments from inlraspecific interactions. Duringthis experiment, a raccoon raided the stream array.Predation by the raccoon was a stochastic eventwhich was not incorporated into the experimentaldesign; however, the raccoon was not sizc-sclcclivc in preying on larvae. In a secondexperiment, we tested the effects of crayfishprcdalion on varying densities of larvae by raisingfive densities of salamanders (4, 8, 12, 20, and 32individuals/in^) with crayfish cither absent orpresent. Larval growth was negatively density-dependent. Crayfish had little effect on growthand survival of larvae. Competition and inlraguildpredation appear lo have a minimal impact onlarval Pscudoliilon. but transient predators mayplay a major role in regulating the abundance ofstream-dwelling salamander larvae.

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TESTING THE USE OF EGG SIZE AS AMEASURE OF MATERNAL INVESTMENTIN THE MUMMICHOG, FVNDULUSHETEROCLITUS. E.E. Niciu* and L.R.McEdward, Department of Zoology, U Florida,Gainesville, FI.Egg size is a commonly used measure ofmaternal investment across many taxa. In otherwords, egg size is used as a gauge of the energycontent in the egg. Therefore, we assume adirect correlation between egg size and energycontent. This study tcsLs this assumption in asmall estuarine fish, the mummichog, Fundulusheteroclilus. Eggs were analyzed for total energycontent using the acid-dichromale wet oxidationmethod over 7 spawning cycles and 9 females,total sample sizc= 647 eggs. We found nosignificant relationship between egg volume andenergy content. These results show that egg sizeis an inaccurate indicator of energy content.Without the use of egg size as a predictor of thelevel of maternal investment in each egg, there arcsignificant ramifications on the ability lo lest lifehistory theory. We are unable to quantify theeffects of differences in the level of investedenergy on subsequent offspring fitness as well aselucidate the tradeoffs in resource allocationexhibited by the adult. Therefore, the practice ofusing egg size as a measure of energy content inthe egg must be validated for the organism inquestion.

AN EXPERIMENTAL ANALYSIS OF PHENOTYPICPLASTICITY IN AMPHIBIAN DEVELOPMENTINDUCED I1Y HABITAT DESSICATION. Robert J.Denver"' and Nooshan Mirhadi2 'The University of Michi-gan, Ann Arbor and 2 University of California, Berkeley,CA.

Phcnotypic plasticity in development lime induced byhabitat dcssication has been demonstrated in a number ofamphibian species through the use of outdoor experimentalponds. We have developed a means lo study this phenome-non in the laboratory. Tadpoles of Scaphiopus hammondiiwere raised in cages in an environmental chamber (12L:12D;22-24°C air temp.) containing 10 liters of water and 20 tad-poles/lank (10% Iloltfrctcr's salts; 20 cm water depth). Thewater in one group of tanks (n=4) was gradually reduced byremoving fixed between 0 5 and 1 liter per day while anothergroup was similarly disturbed but water was not removed.Tadpoles subjected to artificial habitat dcssication showedsignificant acceleration of development. Detailed lime coursestudies of developmental changes were done and correlatedwith precocious elevations in whole body concentrations ofthe hormones iriiodothyroninc (T ), thyroxinc (T4) and corti-costcronc (B). The developmental acceleration induced byhabitat dcssicalion depends on the rate of reduction of thewater level and tadpoles show a continuum of response.Experiments using screens in the tanks in which the dilulionalvolume was not changed but the swimming volume wasgradually decreased demonstrate Ihal the response is not dueto ihe concentration of metabolites, waste products orhormones in the water. This experimental system shouldallow detailed analyses of the proximate mechanisms under-lying adaptive plasticity in amphibian metamorphosis.(Supported by NSF grant IBN-9219211).

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SALAMANDERS MEDIATE INTRAGU1LDPREDATION BETWEEN CADDISFLIES:BEHAVIORAL MECHANISMS THAT UNDER-LIE COMMUNITY PATTERNS.Scotl A. Wissinger, Allegheny College, Mcadville, PA& Rocky Mountain Biological Lab, Crested Dultc, CO

Comparative field data from sub-alpine (elev. 3400 m)ponds in Colorado indicate that the dctritivorouscaddisflics Liinnephilus externus and Asyiiarcluanigriculus reciprocally dominate in permanent and noii-permanent ponds, respectively. In a manipulative fieldexperiment in littoral cages, I found that growth anddiet of both species was unaffected by the presence ofthe other. However, Liinnephilus survival was lowerwith than without Asynarchus. Subsequent behavioralstudies in the lab revealed that Asynarchus arc aggrcs -sive intraguild predators on Liinnephilus. These resultssuggest that Asynarchus should dominate in all pondsat our study site. A second set of experiments focusscdon the effect of predation by larval tiger salamanders,Ambystoma tigrinum nebulosum, which occur only inpermanent ponds. In the first of two experimentsconducted in artificial ponds, salamanderspreferentially preyed on Asynarchus relative toLimnephilus. In the second experiment, we found thatLiinnephilus survival was greater with Asynarchus andsalamanders than with only Asynarchus. Subsequentbehavioral studies revealed that Asynarchus are morevulnerable to salamander predation than Liinnephilusbecause their frenetic activity levels lead to greaterdetection rates. These results suggest that salamanderpredation allays intraguild predation in permanentponds, thus explaining the dominance of Liinnephilus.

CHEMOSENSORY ECOLOGY OF MARINECARNIVORY.R.K. Zimmer-FausC*, D.W. Schar,and J.E. Commins. University ofSouth Carolina, Columbia.

Chemical regulation ofpredator - prey interactions ispoorly understood. There is apaucity of field data on preyattractant production and onpredator chemosensory response.We recently have developedmethods to estimate naturalattractant fluxes from livingprey and carrion. Specifically,we are addressing the roles ofdissolved free amino acids andpeptides in mediating carnivory.Our initial work has focused onpredatory blue crabs andscavenging mud snails as theyforage in response to attractantsreleased by living, injured, anddead prey. The composition,concentration and input rates forvarious types of chemo-attractantmolecules vary considerably.Significantly, carnivory isregulated by different suites ofattractant molecules depending onthe type and condition of preyflesh.Supported by NSF IBN 92-22225.

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AN EXPERIMENTAL APPROACH TOWARDSPREDICTING THE INTENSITY OF COMPETITIVEINTERACTIONS FROM BODY SIZE RATIOS.Laska, Mark S.* Rutgers University, NewBrunswick, NJ.

This study experimentally tests the extent towhich the intensity of competitive interactions canbe predicted, a priori, from the ratio of body sizesof species competing for a common limiting resource.Systematic comparisons of the competitive abilityof several test species against a single species, or"zoometer", is assessed in replicated laboratoryexperiments using Cladocerans. Eight species ofDaphnia in competition with two zoometers,Cenodaphnia dubia and D. pulicaria, have beenexamined. Per capita competitive ability (i.e.,interaction strength) is measured as the extent towhich each test species is able to change theabundance and size distribution of the zoometerduring short-term experiments lasting for severalgenerations. Multivariate analyses of varianceshow significant effects of competition on theabundance, body size, and biomass of the zoometers,and on each of their competitors. The abundanceand body size distribution of both C. dubia and D.pulicaria were significantly depressed by each ofthe test species. Positive correlations between percapita interaction strength and increasing sizes ofcompetitors suggest that body size ratios may beuseful predictors of competitive ability.

BULLFROGS (RANA CATESBEIANA)INVADE A NORTHERN CALIFORNIAWATERSHED: IMPACT ON NATIVEFROGS AND HYDROLOGIC FACTORSAFFECTING ESTABLISHMENT.S. Kupferberg, Univ. of California, Berkeley.

I monitored the recent invasion ofbullfrogs into the S. Fk. Eel River andassessed impacts on native frogs (Ranaboylii and Pseudacris regilla). Bullfrogestablishment was associated with droughtyears; recruitment was low after high rainfallyears and streambed scouring events.Where bullfrogs were well established,reproduction by B- boylii was rare, 6.5clutches/km vs. 83 clutches/km upstream ofbullfrogs. To determine the extent of larvalcompetitive exclusion, I manipulated tadpole.species composition and density in the field.[Bullfrogs had a great impact on R. bovlii.1(48% reduction in survival, 24% decline inmetamorph size), but only a slight impact on'£. regilla. In contrast, competition within thenative tadpoles was slight or insignificant.Bullfrog tadpoles also perturbed aquaticcommunity structure by significantlychanging quantity and quality of algal foodsand altering invertebrate grazerassemblages.

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TEMPERATURE-DEPENDENT SEXDETERMINATION INFLUENCES THEMORTALITY OF HATCHLING SNAPPINGTURTLES IN NATURE.F. J. Janzcn. Iowa State Univ.

To investigate the evolutionary significance oftemperature-dependent sex determination (TSD), Iincubated eggs of the common snapping turtle(Chclvdra scrpcnlina) at a mule-producingtemperature (26°C), a female-producing temperature(30"C), and an intermediate temperature thatproduced both sexes about equally (28"C).Hatchlings from cooler incubation treatments swamfaster than turtles from warmer incubation treatments(P < 0.05) and hatchlings from 28°C exhibited agreater propensity to run than did individuals from26°C and 30°C (P < 0.05). In the field, hatchlingsfrom 26°C and 30*C had significantly higher first-year survivorship than did con.scxuals fiom 28"C (G= 6.622, P < 0.05). Significant ducctional selection

was detected on propensity of hatchlings to run (p" =-0.758, P = 0.05): turtles that tended to remainimmobile had a higher probability of first-yearsurvivorship than did individuals that moved readily.Thus, the effects of the gcndcr*incubationtemperature interaction on survivorship of hatchlingturtles may have been mediated by temperature-dependent antiprcdator behavior. These resultsprovide a possible functional explanation for theevolutionary significance of TSD in turtles that isconsistent with predictions of theoretical models.

LARVAL RECRUITMENT DETERMINES VERTICALSTRUCTURE OF SOME CARIBBEAN REEFCORALS.D.B. Carlon. University of New Hampshire, Durham.

I examined patterns of larval recruit, juvenile, andadult abundance in scleractinian corals at three depths andtwo sites on Guana Island, British Virgin Islands. Overall,coral recruitment declined rapidly with dcplh: recruitmentwas highest at 7 m depth, and decreased at IS and 25 m.Corals that brood larvae (Agaricia spp. and Poritesspp.) dominated patterns of recruitment. Juvenile andadult corals of these two genera had highest abundances atthe shallow (6 m) and intermediate (15 m) depths,compared to the 25 m station. Thus larval dynamicsappear to be important in determining the verticalstructure of these corals. Post-settlement processes amongsites may also be important in modifying patterns ofabundance: adult patterns do not necessarily reflectrecruitment patterns. Apparently both larval andbenthic processes are important in the ecology of reefcorals.

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MALATHION INDUCED CHANGES IN LYMPATHICSYSTEM OF A CATFISH, HETEROPNEUSTESFOSSIUS. A TEM OBSERVATION.H.M. Dutta*, J.S. Datta Munshi and P.K. Roy, KentState University, Kent, Ohio and BhagalpurUniversity, Bhagalpur, India.

When H. fossilis is exposed to 4 mg/Lmalathion for 24h, 48h, 72h, and 96h, the lymphaticsystem is greatly effected. With 24h exposure, thelymphatic spaces become apparent, and a numberof chloride cells appear which protrude toward themargin of the secondary lamellae. With 48h ex-posure the lymphatic spaces enlarge in order toaccommodate a large amount of plasmatic exudate.The chloride cells come into direct contact withlymphatic space and the exterior. With 72h ex-posure the lymphatic spaces with some macro-phases become very prominent. The central bloodchannels become filled with leukocytes. The 96hexposure exhibits a narrowing of lymphatic spacesbut a large number of leukocytes are visible in thecentral blood channel. This study reveals that thesublethal dose of malathion triggers the immunesystem of the fish. The changes in the lymphaticspaces are initiated at 24h of exposure; severechange occurs at 72h exposure, but at 96h ofexposure a process of restoration starts.

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54 55MARINE GASTROTRICHA OF MEDITERRANEAN EGYPXW.D. Hummon*, M.R.Hummon and H.M.Mostafa.Ohio Univ., Achens and Alexandria Univ.

Based on 336 sice records from 52 lit-toral and shallow sublittoral sites (1.5-3m depth) at 17 locations, 66 species (30Macrodasyida, 36 Chaetonotida) are knownfrom Alexandria west to 'Agiba, just pastMarsah Matruh. Of these, some 50 (23 M, 27C) are also known from Greece, Cyprus S/orIsrael in the eastern Med and Aegean Seas,and 50 (23 M, 27 C) from the west coast ofItaly in the western Med', comprising nearlyone-third of the species known from Italy.Beaches protected from west winds are themost productive in species richness. BeauSite (at Matruh) had the richest littoralzone with 18 (6 M, 12 C) species. BeauSite, Boghoush (east of Matruh) and twolocations near Alex had the richest subli-toral sites, with 10-15 (5-9 M, 3-9 C)species. Open coastal locations showedless than half of these values. Severalendemic species also have been found. Foigastrotrichs, the Mediterranean acts as alarge semi-enclosed sea. Of some 200species, 20 or so may be common to all itsshores, with another 30 also having a N.Atlantic connection; the remaining speciesappear to be regional endemics, thoughwidely distributed. (Supported by a Ful-bright Senior Research Scholarship & anOhio Univ. Research Commiltee grant to WD11) .

FINE-STRUCTURAL OBSERVATIONS O NTHE PROBOSCIS OF ALAURINA SP.(TURBELLARIA, MACROSTOMIDA)J. P. S. Smith III. Winthrop University, Rock Hill,South Carolina

Specimens of the unusual pelagic flatworm Alaurinapossess a conical, unciliated proboscis at the anteriortip of die body. The surface of this proboscis has beendescribed as "papillate" by light microscopy. Exami-nation by transmission electron microscopy reveals anassociated frontal gland complex spread out on thelength of the proboscis; large rhammites open in tractsassociated with monociliated sensory cells. The "pa-pillae" seen by I ightmicroscopyconipri.se the openingsof two types of glands, both producing small bacillarysecretions, and opening into a surrounding collar ofmicrovilli. The "papillae" thus fulfill some of themorphological criteria of duo-gland adhesive organs.While duo-gland adhesive systems have a well-definedfunction among interstitial psanimobiontic turbellai-ians, namely that ofsubstrate attachment, it is less clearhow such micro-organs would be of use to a pelagicorganism. Likely hypotheses include prey capture andperhaps substrate attachment, as the highly seasonaland predictable appearance of Alaurina in the estua-rine plankton suggests that it may be :\ dispersal phase.Suppoitcd by funds from ihc Wimliiup UniversityOffice of Development.

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A PHYLOGENY OF ECHINODERM CLASSES BASEDON THE MORPHOLOGY OF THE AXIAL COMPLEX.E.J. Balser. Smithsonian Marine Station, Ft. Pierce, FL

Developmental, structural, and ullraslructural exami-nations of five of the six extant echinoderm classes wereconducted in order to describe the axial complex and toprovide characters for cladlstlcal analysis. The resultsof these studies show that an homologous pore canalhydropore complex and its adult derivative, the axialcomplex, are present in all echinoderms examined. Theadult complex in asteroids, ophiuroids, and echinoidsconsists of the stone canal, pericardium, madreporicpores and ducts, and the axial coelom, which forms theglomerulus of the axial gland, ampulla, and part of themadreporic ducts. Crinoids and holothuroids alsopossess an axial complex, but it lacks a pericardiumand is not associated with the axial gland. Theoccurrence of a similar organ system, the heart-kidneycomplex, in the Hemichordata, supports a commonancestry with the Echinodermata, and justifies usinghemichordates as an evolutionary outgroup. Cladisticalanalysis of axial complex characters separatesechinoderm classes into two monophyletic clades, oneincluding asteroids, ophiuroids, and echinoids and theother holothuroids and crinoids. Traditionally, ennoidsare believed primitive among echinoderms and are notthought to be closely related to holothuroids. Sharedderived axial complex characters, however, link thesetwo classes and suggest that this clade is evolulionallymore derived than that of asteroids, ophiuroids, andechinoids. Research supported by NSF Grant#9006500 to E.E. Ruppert and a Smithsonian Fe"swsh!pto E.J. Balser.

ONTOGENETIC VARIATION PARALLELSPHYLOGENETIC VARIATION IN COLONYFORMATION OF HYDRACTINIIDHYDROIDS.N.W. Blackstonc. Northern Illinois Univ.,DeKalb.

Image analysis of the morphology and videomicroscopic analysis of the gastrovascularcirculation of 10 full-sib colonies of Hydractiniasymbiolongicarpus from metamorphosis toreproduction demonstrates that as the onlngcnyprogresses (1) the volumetric rate of circulationto the periphery of the colony diminishes and(2) the morphology becomes more sheet-like.These data parallel the phylogenetic differencebetween H. symbiolongicarpus and Podocoryneearned. Compared to the latter, ihe formerspecies is more sheet-like and exhibits roughlyhalf the peripheral circulation. Experimentalmanipulations of circulation and morphologycomplement this naturally occurring variation.These data support the hypotheses thatcirculation triggers morphogenetic processesand that heterochronic alternations in circulationgenerate diversity in hyiiract'niid hyilroiiis.

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58 59RESPONSES OF DINOFLAGELLATES(ZOOXANTHELLAE) TO SYiMBIOSIS WITHSEA ANEMONES {Aiptasia pallida )COOK, C. B.* and D. M. OLSON.Harbor Branch OceanographicInstitution, Ft. Pierce, FL

Freshly isolated (FIZ) andcultured (CZ) A. pallidasymbionts were compared withrespect to sensitivity to hostfactors (HF) which stimulate therelease of photosyntheticproducts. FIZ displayed thetypical symbiotic response ofincreased release, but release byCZ was inhibited by HF. When CZwere grown in aposymbioticanemones, they exhibitedincreased release in the presenceof HF within two weeks, andresponded as normal FIZ withinsix weeks. When FIZ wereisolated from anemones intoliquid culture they lostsensitivity to HF within 24hours. HF levels in symbioticand aposymbiotic anemones weresimilar, indicating that thepresence of zooxanthellae hadlittle effect on the productionof HF.

TISSUE REGENERATION ANDMORTALITY IN A FREE-LIVING HERMATYPICCORAL.N.E. Chadwick-Furman. Bar Han University, Ramat Can,Israel.

Patterns of natural tissue damage and regenerationin corals may in part predict the rate at which reefs canrecover from disturbances. At Eilat, Red Sea, free-livingpolyps of the mushroom coral Fungia granulosa sufferedpartial mortality from Black Band Disease, endosymbioticcrabs, and parasitic snails (Epilonium). In addition, highwater motion during seasonal storms abraded and buriedcorals. Following damage events, polyps diverted energyaway from skeletal growth to rapidly regenerate tissue. Incases of extensive damage, encrusting invertebratescolonized the exposed coral skeleton and competed withregenerating tissues, sometimes leading to the death of theentire coral. Juveniles had much higher mortality (up to80% per year) than did adults. These results indicate acomplex cycle of frequent tissue damage and recoveryevents in a reef coral, and strong dependence of recoveryrate on coral size.

60 61SOLAR UV-A INHIBITION OF PLANULALARVAE IN A REEF-BUILDING CORAL.A.C. Baker. RSMAS, University of Miami.

Ncwiy-rdcascd planulac from adulicolonies of the sclcractinian coral Pocilloporadamicornis were subjected for 2 weeks lo oneof 3 UV treatments using solar filters. Inthose treatments where UV-A and UV-Bwere screened out, the initial rate of larvalsettlement increased, and the final number oflarvae settled (reproductive success) reached37.3% (±3.7%), compared'to 20.8% (±4.9%)with removal of UV-B alone, and 13.1%(±3.1%) under control conditions with neutraldensity filters. These results argue for theecological significance of UV-A as adeterminant of larval settlement success.Screening of parent coral colonies from UV-Aand UV-B for one lunar month prior toplanulation produced larvae with reduced UVtolerance, measured both by larval settlementsuccess and quantification of myeosporine-like amino acids (MAAs) in the larvae. Thissuggests differential investment in larval UVblockcrs in response to environmentalconditions.

THE EFFECT OF ULTRAVIOLET RADIATIONON MARINE SYMBIOTIC ASSOCIATIONS.A. T. Banaszak' and R. K. Trench.Smithsonian Environmental Research Center,Edgewatcr, MD and University of California,Sanla Barbara, CA.

The tropical, upside-down jellyfish, Cassiopeiaxamuchana and its symbiont Symbioiliniummicroadriaticum in culture, were exposed to artificialultraviolet (UV) radiation for 8 weeks. The responseof the symbiotic association was studied by analysi.sof the intact association and of the partners inisolation. S. microadriaticum in culture releases threemycosponne-like amino acids (MAAs) to the culturemedium. Using high performance liquid chromato-graphy (HPLC), Mycosporinc-glycine was found inhighest concentration with porphyra-334 and shmorincfound in lower concentrations. Aposymbioticscyphistomae (polyps) of C. xamachaita produce noMAAs even when exposed to UV, whereas symbioticephyrae (juvenile jellyfish) and adult jellyfish, assayedafter removal of the algae, contained the same threeMAAs found in S. microadriaticum. Taken togetherthese data are consistent with the concept that S.microadriaticum synthesiscs MAAs and translocatesthem to the host. By contrast, the symbiosis betweenthe temperate anemone Anlhopletira cleganlisstina andS. californium responds differently to the presence ofUV than docs C. xamiichmia.

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FUNCTIONAL TRADEOFFS ONTHREESPINESTICKLEBACK BODY AND FIN SHAPEJ. Walker. Stale University of New York at Stony Brook.

Important behavioral components of fitness include thesearch for prey and escape from predators. Morphologiesthat can enhance foraging performance, however, may limitescape performance and vice versa. In fish, for example,increased caudal depth should enhance the performance ofescape bchaviois that use rapid accelerations and turns butlimit the performance of foraging bclmviors that usesustained swimming. Foraging in open water under thethreat of prcdation, lliciclorc, presents opposing patterns olselection on caudal phcnolypc. To investigate theinteraction of foraging and antiprcdator behaviors on fishbody shape, the effects of foraging habitat and prcdationregime on mean body and fin shapes of thrccspincstickleback sampled from 40 lakes were analyzed. Relativeto the ancestral phcnolypc, su'cklcback in shallow lakeswith nalivc predatory fish have maintained long median finsbul have increased caudal body depth. Stickleback in deeplakes with nalivc predator)' fish have also maintained longmedian fins but have reduced caudal body depth. Sticklebackin all lakes lacking nalivc picdalory fish have reduced bothmedian fin length and caudal body depth. The contrast in theobserved patterns of shape variation illustrates an effectivesolution to the opposing patterns of selection resultingfrom foraging in open water under threat of prcdauon.Unlike the caudal body, the median fins can be erectedduring fast starts and powcicd turns and collapsed duringsustained swimming. This vcisatility results in a functionaldecoupling between caudal body shape and fin shape. Suchdecoupling effectively allowed the evolution of shallowcaudal bodies in combination with long median fins instickleback colonizing deep lakes with native predatory fish.

EFFECTS OF BODY SIZE ON KINEMATICS OFPECTORAL FIN LOCOMOTION IN STRIPEDSURFPERCH.E.G. Dnicker* and J.S. Jensen. Harvard Univ.,Cambridge, MA.

The objective of this study was to test whetherlocomotory scaling relationships observed forteirapods apply to fishes that also rely on pairedappendages to power locomotion. The surfperches(Teleostei: Embiotocidae) employ pectoral finlocomotion over a wide range of swimming speeds.In order to investigate the effect of body size onlocoinolory kinematics in ihis group, we videotapedstriped surf perch varying 5-fold in length and I(X)-fold in mass swimming steadily in a large flume.Stride frequency (pectoral fin beat frequency) and.stride length were measured as a function olswimming speed within each size class, and as afunction of size at a physiologically "equivalent"speed (i.e. at the gait transition from pectoral finoscillation to axial undulation). Locomotorykinematics show a clear size-dependency. Tomaintain a given speed, smaller-fish use higherstride frequencies and smaller stride lengths thanlarger fish. At ihe gait transition speed, stridefrequency is proponional to (body mass)" "•', stridelength to (body mass)l)-3, and swimming speed to(body mass)()-2 These allomctric relationshipsclosely match those determined for tctrapods byTaylor and colleagues, indicating that they mayapply broadly to aquatic as well as terrestrialvertebrates.

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EVOLUTION Ol' FAST STARTS IN BASALACTINOPTERYGIAN FISHES: DECOUPLEDLEVELS OF FUNCTIONAL DESIGNM. E. Hale*1, M. J. Mcllcnry2, M.W.Weslncal^. and J. I I . Long, Jr.2 I University ofChicago, 2Vassal- College. NY, and VieldMuseum ol Natural History, Chicago.

The kinematics, intramuscular pressure, andEMG firing patterns of axial locomolor musclewere examined in the fast starts ol" lour basalaelinoplcrygian laxa: Polyptcms. Lepi.sosleus,Am in. and Oncorhvnehus. The evolution of theseaspects of I'a.sl Mart performance was examined byinlcrprcling performance features withphylogenelic methods. Characters of the fast startwere identified, including body curvature, EMGduration and onset limes, magnitude and time ofrising of internal pressure, and escapeperformance (velocity). Characters were codedand optimi/.cd onto ihe phytogeny of basaluclinoplcrygiuns to reveal their evolutionarypatterns. Results .show decoupled evolution offactors affecting performance. While somecharacters .such as magnitudes of internal pressureare .similar across laxa, others show diversephylogenelic patterns. EMG characters include asynjpomorphy for Anna + Oncorhvnchiis in thepresence of EMG during phase 2 of the fast start.EMG ai.su cxiiiniijd sluing iHiiiii];)id.sy in .severaloilier timing features. We conclude that the motor-..:::, 1. :' l-v. -:_ •: \ _•. .r>:.-.-. is - . : „-. r-jrv :;:%..•throughout early uclir.ijpterygian evolution.

CON TRACTION KINETICS AND POWERPRODUCTION OF SCUP PINK MUSCLE.D. J. Coughlin and L C Rome Umvcisilv ofPennsylvania. Philadelphia.

Pink iiivoloinnl muscle in fish has the same fiberorientation as red muscle and is used lo powercontinuous swimming al speeds near Ihe Ihicshold ofaciobic activity. The contraction properties and powerproduction of pink swimming muscle taken from theanterior region of scup mvolomc wcic examined at IIIand 20°C. Pink muscle showed fnslcr rates ofactivation and relaxation than red muscle fiom similaranalomicnl position (eg time for iclaviuon from VO lo10% of peak tetanic foicc was X2 2H'J 1 ins in pinkmuscle versus 165±lK.7ins in icd muscle). 'The V[t,x ofpink muscle (7.26±0.55 ML s ' al 2(>°C and 4.46±0.37ML s' al 1()°C) was gicalcr than that for red muscle b>a factor of appioxinialcly 1.3 ,il each temperature andshowed a Q,L of about 1.6, similar lo red muscle Thefrequency of maximum power production for cvclicaclivilj under optimised conditions was also gicalcr inpink muscle than red muscle by a factor ofapproximate!) I 3 (6.75 HZ for pink \s. 5 H/. for red al2I)°C , 1.2S HZ for pink vs.2.5 H/. foi red al HIT).Last!), power production was measured for pink musclestimulated under ihe activm patterns recorded in vnnfrom red muscle. Pink muscle produced considerablemore power than rod under these conditions, particular!)al id'C Supported b> NIH and NSF

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66 67CAUDAL FIN LOCOMOTION BY TELEOSTFISHES: FUNCTION OF THE HOMOCERCALTAIL.G. V. Lauder. Dept. of Ecology and EvolutionaryBiology, Univ. of California, Irvine.

The homocercal tail, with its externallysymmetrical dorsal and ventral lobes,characterizes many teleost fishes and has beenpresumed to function symmetrically duringlocomotion. In contrast, previous work onheterocercal tails has shown that theasymmetrical morphology of the tail is correlatedwith asymmetrical function. In this study, thekinematics of the homocercal tail in a teleost, thebluegill sunfish (Leoomis macrochirus). wereexamined in four individuals swimming in a flowtank at two steady speeds (1.2 and 2.2 TL/sec)and during unsteady burst-and-glide swimming.Both lateral and posterior views were obtained,allowing the position of four marked points on thecaudal rays to be followed in three dimensions.Results show (1) that tail beat amplitudeincreases with swimming speed, (2) that thedorsal lobe of the tail undergoes greater lateralexcursions than the ventral lobe, and (3) that thecaudal fin is not vertically oriented through the tailbeat cycle. Thus, the dorsal and ventral lobes ofthe homocercal caudal fin may functionasymmetrically even during steady forwardlocomotion. Asymmetrical function may generatelift forces in a manner similar to heterocercal tails,and this asymmetry may be due to the action ofthe hypochordal longitudinalis, an intrinsic tailmuscle.

KINEMATICS OF LOCOMOTION IN WATERAND ON LAND BY THE EEL, Anguilla rostrata.G.B. Gillis. Univ. of California, Irvine.

Transitions between aquatic and terrestrialenvironments are known to occur during the lilehistories of numerous vertebrate taxa. Eels(Anguilla) for example, which are primarilyaquatic, are well known for their occasionalexcursions onto land. In this study, I examinethe effects of such an environmental transitionon axial movements during locomotion in theAmerican eel, Anguilla rostrata. Individuals werevideotaped at 250 fields per second swimming ina flow tank, or undulating across wet packedsand at comparable speeds (0.4-0.5 L/s). Eeloutlines from 20 fields per tailbeat cycle weredigitized for 4 tailbeat cycles in eachenvironment. Computer calculated midlinesgenerated for each field were used for. kinematicanalysis. The relationship between theamplitude of lateral displacement andlongitudinal position down the body variesdramatically during undulatory locomotion acrossenvironments. For example, during swimming,amplitude increases along the entire body fromapproximately 0.006L at the snout to 0.07L atthe tip of the tail. In contrast, during terrestrialundulation amplitude is much greater and ishighest at the tip of the snout and tail (0.17 and0.18L, respectively), and is relatively low in themiddle portion of the body, 0.07L. Such dilferentaxial movements imply thai eels are capable ofmodulating their motor pattern depending onenvironment.

68 69ARE MUSCLE FIBERS WITHIN FISH MYOTOMESACTIVATED SYNCHRONOUSLY?B.C. Jayne and G.V. Lauder*. Univ. Cincinnati andUniv. California, Irvine.

To clarify patterns of muscle recruitment within fishmyomeres, we implanted fine-wire electrodes using avertical row of six and a longitudinal row of three withineach side five largemouth bass (MicroptRiussalmoidesV We recorded electromyograms (EMGs)during burst and glide swimming. Post-mortemdissections and x-rays verified electrode positions bothwith respect to myomeric location and relative to theunderlying axial skeleton. EMG onset times differedsignificantly among sites within each vertical rowwhich had electrodes in any one of six differentmyomeres. Within the longitudinal row, EMG onsetsat more posterior (by vertebral number) sites precededthose of more anterior sites if the more posteriorelectrode was in a myomere anterior to that of themore anterior (by vertebral number) electrode. Hencedifferences in the timing of EMGs were betterpredicted by myomeric number than by longitudinalposition indicated by vertebral number. The timing ofEMGs was consistent with the posterior propagation ofmuscle activity via the sequential activation ofmyomeres rather than the simultaneous activation ofall contractile tissue within the longitudinal span ol asingle vertebrae. In addition, extreme epaxial andhypaxial portions of myomeres showed distinct activit>patterns which did not necessarily correlate withactivity in the central myomeric fibers nearer thehorizontal septum.

Effect ol Temperature on Muscle Function DuringJumping in Frogs (Rana pipien$. G.J. Lutz" and L.C.Rome. Univ. of Pennsylvania., Philadelphia.

We measured the kinematics and jumpingperformance of Rana pipiens during maximal lumps at15 and 25°C as well as the sarcomere length (SL)excursion and electromyogram (EMG) in thesemimembranosus muscle (SM) during he jumps. Thereduction in temperature caused a decline in peakpower production from 66.8 to 37.5 W kg ' of bodymass and a corresponding decrease in maximal jumpdistance from 0.68 to 0.42 m. In addition the delaybetween the beginning of the'EMG and the onset ofpower production was increased by a factor of 2. Bycontrast total strain and SL excursion of the SM wereindependent of temperature while shortening velocity(V) was decreased from 3.94 to 3.34 ML/s (musclelengths/s). Comparison with the mechanical propertiesof SM bundles showed that during jumping at bothtemperatures the SM shortened over a range of SL'swhere no less than 90% ol maximal force would beproduced and shortened at a VA/,^ between 0.32 and0.45, where near maximal power is produced. Whenthe SM was driven through the in vivo length changeand stimulus conditions, the force was equal to theforce found at the same velocity on the steady-stateforce-velocity curve, indicating that the SM wasmaximally activated throughout shortening. Thesefindings suggest that the components of the frogmuscular system such as V^,, fiber gearing, jointmoments and the kinetics of activation are appropriatelyset so that maximal power is produced during jumping.

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MUSCLE ACTIVITY IN THE TAILS OF LIZARDSAFTER CAUDAL AUTOTOMY.J.M. Rumping* and B.C. Jayne, Univ. of Cincinnati.

Many lizard species can lose a portion of the tailas a natural defensive behavior, and previousstudies have found that the extent of tail movementafter autotomy affects predator deterrence. In thisstudy, we used electromyography to determine themuscular basis of tail movements and to examinethe stereotypy of motor pattern that occurred inthese isolated portions of the spinal cord. Weimplanted a total of 14 bipolar, electrodes in the tailsof 5 Tokay geckos (Gekko gecko) at six longitudinalpositions, including sites on left and right sides andin epaxial and hypaxial muscle. Electromyograms(EMGs) were recorded for the entire duration ofmuscle activity after autotomy, which lasted for 10 to40 minutes. The motor pattern was fundamentallyrhythmic and alternated between the left and rightsides at each longitudinal location. EMGspropagated from posterior to anterior, in contrast tothe direction of propagation found for fictivepreparations of lower vertebrate spinal cords.Analyses of variance revealed widespread effects oftime (after autotomy) and longitudinal location onEMG variables. EMG duration decreased with timeand increased from anterior to posterior. EMG cycleduration and intersegmental phase lags bothincreased significantly with time after autotomy. Theintensity of EMGs diminished with increased timeand muscle activity ceased earliest at more anteriorsites.

HIND LIMB FUNCTION DURING WALKING INTHE SALAMANDER Dicamptodon tenebrosus.M. A. Ashley-Ross. Univ. of California, Irvine.

In this study I address the neuromuscularcontrol of the hind limb during locomotion insalamanders. Hind limb kinematics duringterrestrial locomotion in Dicamptodon werestudied and compared to those of othertetrapods. The stride is characterized byuninterrupted trunk and pelvic girdle oscillation,femoral retraction throughout stance phase, andknee flexion in early stance followed byextension. Dicamptodon shares the followingfeatures of the hind limb step cycle with othertetrapods: pelvic girdle rotation of 30 to 40°,femoral retraction throughout stance phase,knee flexion in early stance, and knee extensionin late stance. Electromyography of hind limbmuscles during walking in Dicamptodonrevealed that ventral muscles become activejust before the start of the stride, and maintainactivity through the first half of stance phase.Dorsal muscles show activity during the first halfof swing phase. Several muscles show avariable secondary burst during the stride.Comparison of muscle activity periods forDicamptodon with other tetrapods revealssimilarity for all ventral muscles and for twodorsal muscles, suggesting conservation ofmotor patterns for some muscles.

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EFFECTS OF LOCOMOTOR SPEED ON HIND LIMBKINEMATICS OF A LIZARD.C.L. Fieler* and B.C. Jayne. Univ. of Cincinnati.

We videotaped (250 images/s) desert iguanas(Dipsosaurus dorsalis) moving on a motorizedtreadmill over a wide range (ca. six-fold) of speeds.We performed a frame-by-lrame kinematic analysis ofthe hind limb for sequences including bothquadrupedal and bipedal locomotion. The followingpreliminary analysis is based primarily on oneindividual with a snout-vent length = 5.9 cm, but weobserved additional lizards with SVL up to 11 cm. Aslocomotor speed increased, stride frequency increasedfrom 5.4 to 10.4 Hz, and stride length increased from6.4 to 18.4 cm. At speeds exceeding 110 cm/s,bipedal running was common. Foot posture during thestance phase also changed substantially withincreased speed. At slow speeds, the entire plantarsurface of the foot contacted the ground, whereas; footcontact was commonly limited to the phalanges andthe distal portion of the metatarsals at intermediatespeeds (>90cm/s). At maximal speeds, (>125 cm/s)contact was often limited to the distal two phalanges ofthe fourth toe. Hence, over a wide range of rapidspeeds lizards may use a digitigrade foot posture. Thecontribution of the tibia to the effective limb lengthchanged little with speed, whereas; increased amountsof femur adduction and plantar flexion increased thecontributions of the femur and foot at increased speed.The lengths of the fourth toe and pes approximate110% and 175% of the tibia! length, respectively.Thus, in_D_. dorsalis. the distal limb elements cancontribute considerably to the effective limb length.

BURROWING PERFORMANCE ANDKINEMATICS IN THE EASTERNSPADEFOOT TOAD, SCAPHIOPUSHOLBROOKI.A.P. Summers* and P.R. Delis. University ofMassachusetts Amherst and University ofSouth Florida.

It has been proposed that the EasternSpadefoot Toad, Scaphiopus holbrooki, is easilyexcluded by urbanization. We investigated thepossibility that exclusion is caused by afunctional constraint. During periods ofinclement weather the Spadefoot will dig, hindend first, into the soil to a depth of up to 2meters. Performance tests supported thehypothesis of a functional constraint. Toadswere timed until they had burrowed out ofsight in six different substrates. Two of thesesubstrates were typical of the natural habitatand four were typical of more developed areas.Burrowing in the developed habitat substrateswas significantly slower than in natural habitatsubstrates. We describe the kinematics of hindend first burrowing using high-speedcineradiography and compare it to the work ofEmerson (J. Morph., 1976) on the microhylidGlyphoglossus molossus.


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HOW DO BASILISK LIZARDS (Basiliscus basiliscus)SUPPORT THEIR BODY WEIGHT ON THE WATERSURFACE?J.W. Glasheen* and T.A. McMahon. Harvard Univ.,Cambridge, MA

Organisms which live at the air-water interface must beable to support their body weight on the water surface.Typically, a combination of hydrostatic forces supportmost organisms such as water striders (surface tension)and ducks (displacement). In contrast, basilisk lizardsutilize hydrodynamic forces to resist the pull of gravity.In order to understand the sources of the basilisk'ssupport force, we recorded with high-speed video (500frames per second) 10 basilisks of a range in sizes (2.25g -104 g) as they ran across the water surface. Alaboratory simulation of the lizard's foot motions allowedus to assess the forces generated at various points inthe step. On the basis of both the kinematic data andthe simulations, we developed a hydrodynamic modelof the basilisk's support force that consists of threephases: (i) an upward force impulse is generated whenthe foot slaps the water surface and suddenlyaccelerates a volume of water downward; (ii) anadditional upward force is produced when the footstrokes down into the water while entraining an air cavitythat is continuous with the water surface; (iii) resistiveand reactive forces associated with foot protraction areminimized by pulling the foot out of the water beforethe air cavity collapses. One prediction of the model isthat as body size grows, the relative importance ol theslroke phase increases. The limited extent to which thestroke force can contribute to the overall upward forceeffectively sets a limit to the maximum sized lizard lhalcould support its body weight in this manner. Thepredictions of the model are compared withobservations of basilisks.

A DUAL ROLE FOR THE ABDOMINALMUSCULATURE OF RUNNING BIRDS. P. N.Nassar, Bryn Mawr College, PA.

Although previous studies of the respiratorymuscles of resting birds have shown the abdominalmuscles to be active during expiration, thesemuscles may also function during locomotion toprovide postural and abdominal support. To testwhether the abdominal muscles aid in ventilationand / or stabilize the body during locomotion, Imeasured activity in the external oblique, internaloblique, and transverse abdominal muscles of fourguinea fowl (Numida meleagris) running on atreadmill (1.25 - 2.75 m / s). Locomotion wasmonitored with video (120 frames / s) and bysecuring an accelerometer to the animals' backs.Ventilation was measured with a bidirectionalthermistor flow probe mounted over one of thenostrils. As the birds ran and thermoregulatorypanting set in, ventilation coupled with locomotionat two breaths per stride, with expiration occurringduring the acceleration period of limb support.Activity from all three abdominal musclescorrelated primarily with contralateral limb support.During non-panting intervals ventilation decoupledfrom locomotion. When ventilation was notcoupled to the stride, the activity of the abdominalmuscles remained tied to the locomotor cycle.These observations suggest that the abdominalmuscles play a role in both locomotion and ventila-tion, but that the former system can supersede thelatter. Support from NSF IBN 9306466.

76 77

LOCOMOTOR PERFORMANCE IN SCIUR1DSJ. Gray dickering, Brown Univ., Providence, RI.

The study of vertebrate locomotion has revealedmuch about skeletal and muscular design in awide variety of animals. However, few studieshave quantified locomotor performance in taxawith generalized or primitive locomotory modes,or have quantified locomotion in a controlledsetting, a rcquiiement for rigorous testing ofhypotheses relating structure to function. Squirrelshave been proposed as models for primitivemammals, but the full range of locomotorcapabilities of even common species arcunknown, although many species arc designatedas primarily arboreal or primarily terrestrial. 1quantified sprint performance in response to alarmin wild-caught sciunds and analyzed the effects ofhabitat architecture, lifestyle mode, and body size.Performance trials were conducted and video-recorded in an enclosed track with four "branches"of diameters 0.95, 2.2, 4.9 and I 1.4 cm and a flatsurface. The maximum speed out of at least fourtrials on each branch size was obtained for grey,Abert's, and red squirrels, least chipmunks, andsouthern flying squirrels. Preliminary resultssuggest some trends regarding the effects ofbranch size, lifestyle mode and body size. Ingeneral, maximum sprint speed tends to increasewith increasing branch diameter in all species.The single more terrestrial species is slower for itsbody mass than arboreal species. A generaldecrease in speed with increasing body size wasobserved among arboreal squirrel species.

IN VIVO MUSCLE FORCE GENERATIONAND STRAIN ENERGY STORAGE IN THEHOPPING OF WALLABIES.A.A. Biewcner* and R.V. Baudinette.Univ. of Chicago, Chicago, IL and FlindersUniv., Adelaide, South Australia.

We made in vivo muscle-tendon force bucklerecordings of the gastrocnemius (G), plantaris (PI)and flexor digitorum longus (FDL) muscles of fourtammar wallabies (M. eugenii) hopping on a treadmillfrom 2.5 to 6.3 m/s. Force sharing among the threemuscles was uniformly maintained for most speedsand animals studied. Muscle stresses > peak isometricstress (200 kPa) were recorded in the PI and G atspeeds greater than 4 and 5 m/s, reaching 260 kPa inPI; at all speeds the muscles were actively stretchedprior to shortening. Being the thinnest of the threetendons, peak strains and strain energy storage weregreatest in tendon of G, compared with the longer PIand FDL tendons. Strain energy storage was lowestin the FDL tendon. Significant elastic energyrecovery is achieved by the stretching and recoil ofthese three hindlimb tendons during each hop,increasing from 1% (8 W) at 3.0 m/s to 24% (26 W)of metabolic power consumption (110 W) at 6.0 m/s.[supported by NSF grant IBN-9306793]

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LOCOMOTOR-CARDIAC COUPLING INTROTTING DOGS. A. D. Simmons * and D. R.Carrier. Brown University, Providence.

When skeletal muscles contract, intramuscularpressures often exceed systolic blood pressure. Tofacilitate effective blood flow, we expected theheart to contract during intervals in the locomolorcycle which would allow blood to reach ihe majorlocomotor muscles when they were relaxed. Totest this hypothesis, we ran three dogs on amotorized treadmill and recorded activity of theheart with surface electrodes and recorded stridewith both an acccleromctcn mounted on the dog'sback and high speed video. We analyzed theperiodicity and phase relationship of the twocycles. We found that heart rate was usuallygreater than stride frequency. Consequently, thetiming of heart activity varied relative lo thetiming of stride events. Locomolor-cardiaccoupling was observed in two dogs duringtrotting, but only briefly. Coupled sequenceslasted for 10 to 20 heartbeats (5 lo 10 s) andexhibited a lower hemt rate than uncoupledsequences. When the heart was coupled to stride,heartbeats occurred near the lime of foot sit ikeThe lower heart rale and constant phaserelationship between the two cycles suggest thatthis phenomenon is more than a simple matchingof similar frequencies. However, the transientnature of Ihe observed coupling raises questionsabout its significance, paiticularly in a lessrestricted outdoor setting on variable terrain.Supported by NSF 1BN 9306466.

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The Crustacean Society

79 80Pattern of exoskeletal abrasion andreproductive readiness in the malespider crab, Libinia emarginata.J.S.3. Ahl, P. Takac, A.J. Ahl, G.Rotllant, and H. Laufer. Univ. ofConnecticut, Storrs.

Large-claw males were separatedinto 6 categories based upon thepattern of epicuticular abrasionpresent on the carapace. Abrasionfirst appears inferior and lateralto the sulcus of the eyestalk onthe frontal portion of the carapacethen it appears on the dorsum justposterior to the rostrum and eye-stalks. Abrading follows the mid-dorsal spines, then spreads overthe branchial chambers in an anter-io-posterior fashion. During abra-ding, the reproductive system en-larges and the hemolymph levels ofmethyl farnesoate steadily increaseThe size of the gonad increasessignificantly once abrasion appearson the dorsum. I.iethyl farnesoatelevels are highest when abrasion is2/3 completed. Thus, the patternof abrasion can indicate the stageof reproductive readiness as themales enter the mating season.

GROWTH OF SINGLE EYESTAI-K ABLATFDHAITI II.I NO OUAYHSI I. Cham qnmlni tinniilu.\Mark M. Mcidc* and S.A Walls Umv Al. Birmingham.

Eycslalk ablation procedures arc commonly used toinduce molting in crustaceans. Bilalcrall)-ablatedindividuals typically exhibit high mortality, thus, anc.\ammalion of growth for extended periods is notpossible. In this stud). growth and survival wereexamined in single c\cslalk ablated halchling crajfishNew Iv hatched C'henix qmulntannalus (n=20.')-11 mmsize class) were ablated the day after their first moll.Survival of ablated crayfish after t.cn weeks wassignificantly lower than control crayfish (60% versusV0%, respectively, p < 0 05) Mean fresh weights,however, were not significantly different between ablatedand control crayfish An examination of moll frequenciesindicated that the first and second molls ofablaledcrayfish were 25% shorter in duration than controlcrayfish. By the third moll and thereafter, however,intcrmoll periods of ablated crayfish were not differentfrom control crayfish These data suggest thai singlec\eMalk-alb.ilion\ can he used to increase moltingfrequencies in crayfish without high morlalil) for shortperiods of lime These data also suggest that the Mil Iproducing cells in the single eycslalk of ablated crayfishapparently compensate over time for the lack ofa pairedMIH producing organ, thus, enabling moilingfrequencies to return to intervals similar to those ofimablalcd crayfish.

81

The FL hermit-crab sponge-Pagurus impressus associationis the only portable sponge-hermit crab associationreported from the Gulf ofMexico and has been little-studied. The sponge occupies arestricted range in the NEcorner of the Gulf near DogIsland and currently has novalid scientific name. Studiessince 1992 show that whileseveral hermit crab species mayuse sponge shelters, twospecies -- Pagurus impressusand Paguristes hummi -- are thetypical occupants. In shelter-choice experiments juvenile P.impressus occupy both shell andsponge shelters, but prefershells. Switching from spongesto shells may explain the largenumber of empty sponges thatwash ashore in January, when P.impressus move closer to shore.

ABSTRACTS 17A

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PHOTIC REGULATION 01- MELATON1NSECRETION IN PERI FUSED PINEAL GLANDSOF THE SAILHN MOLLY, Poecilia velifcra.Okimoto, D.K. and M II. Slclson. University ofDelaware.

The ability of isolated pineal glands of the sailfinmolly, Poecilia velifcra, lo produce inelaloninrhythmically under various photopcriodic conditions(e.g., 12 h light : 12 h dark, constant hghi andconstant darkness) and constant temperature (27° C)was investigated using a pcrifusion apparatus.Pincals exposed lo a 12 hr light : 12 hr daik cyclesecreted low amounts of mclatonin during the lightand high amounts during the dark. Constant lightinhibited melalonin release. Under constantdarkness, however, melatonin release was robust andrhythmic with a period of about 24 hr (range 21.3-27.0 hr; n=21) and an avciagc amplitude of 1642pg/ml perfusatc/lir (range 420-3767 pg/ml/hr; n=21).Taken together, these data suggest that the sailfinmolly pineal is directly photosensitive and contains(a) circadiun oscillator(s) which icgulale.s mclatoninproduction. Further characterization of the oscillatoris in progress. This work was supported by NSI-DCB S7-I463S and IISN 93-18203.

INFLUENCE OF THYROXINE ON TISSUEUPTAKE OF 3H-MELATONIN IN BULLFROGTADPOLES.M.L. Wright*, A. Pikula, A. Babski, and K.Kuliga. College of Our Lady of the Elms,Chicopee, MA

Late pre- to prometamorphic Rana catesbeionatadpoles on an 18L:6D cycle (L from 0800-0200hr) at 22°C were injected between 1600 and 1800hr with 5 ftCi of 3H-melatonin (ML) each beforesacrifice one hour later. Tissues were removed,weighed and solubilizcd prior to assay by liquidscintillation counting. 3H-ML uptake was highestin intestine and lowest in thyroid and brain.Thyroxinc (T4) at .007 or .2 /tg/tadpole givensimultaneously with 3H-ML significantlyincreased 3H-ML uptake in tail, ventral skin,hindlimb, intestine and gill tissue. T4 at .007 ngincreased ML uptake of thyroid gland also.Incorporation of 3H-ML into brain and pituitarywas not affected by T4. Selected tissues labeledin vitro for 2 hr showed greater incorporationthan in vivo but the results were basically thesame. The findings showed that, in general,peripheral tissues took up more 3H-ML/mg thanneuroendocrinc ones, and that 'H-ML uptake wasincreased by T4 mainly in peripheral tissues thatundergo major changes in metamorphosis.

94 95

DIURNAL VARIATION IN BRAIN ANDPLASMA o-MELANOCYTE-STIMULATINGHORMONE (o-MSH) CONTENT IN THE TEXASTOAD, BUFO SPECIOSUS.Y. Kim*, A.M. Carpenter, K.J. Gregg, Z.Shahnaz and J.A. Carr. Texas TechUniversity, Lubbock.

We measured the concentrations of o-MSHin hypothatamus, brainstem, optic tectum andtelencephalon as well as pituitary and plasmaof the toad during a 24 h light:dark cycle.There was significant diurnal variation inhypothalamus and brainstem o-MSHconcentrations. In both areas peak o-MSHconcentrations occurred during thescotophase. In contrast, peak o-MSHconcentrations in the plasma were observedat 17.00 h during the photophase. There wasno diurnal variation in pituitary o-MSH contentduring the 24 h light:dark cycle. These datasuggest that different mechanisms controlbrain and pituitary o-MSH cells in the toadduring a 24 h light:dark cycle. The fact thatpeak o-MSH concentrations were observed inthe hypothalamus during the activity period ofthe toad is consistent with the proposed roleof o-MSH peptides in learning and memoryprocesses. Supported in part by the HHMIthrough the Undergraduate BiologicalSciences Education Program.

INFLUENCE OF ACTH/MS11 PEPTIDESAND CORTICOSTERONE ONHAT3ITUAT1ON OF PREY-CATCHINGBEHAVIOR IN THE GREAT PLAINSTOAD, BUFO COCNATUS.A.M. Carpenter*, Y.S. Kim, K.J. Gregg,and J.A. Carr. Texas Tech Univ., Lubbock.

We studied the effect of ACTH/MSHpeptides and corticosterone on habitation ofthe prey-catching behavior in toads. Maletoads were injected with corticosterone,ACTH[1-39J, a-MSH, NDP-MSH, des-acctyl-a-MSII, ACTI 1(4-101 or controlvehicle 30 min prior to acquisition.ACT1I11-39J, ACT1I|4-1O) and a-MSIIsignificantly decreased the number of turningreactions during acquisition in relation tocontrols. The effect of these peptides wasrapid, occurring within the first 20 min ofacquisition. Conicosterone caused a decreasein the number of turning reactions, althoughthis effect was not observed until 40 min afterthe onset of testing. NDP-MSH and des-acetyl-a-MSH did not influence acquisition.ACTH[l-39] was the only peptide to delayextinction. These data indicate that minorstructural differences can dramaticallyinfluence the ability of ACTH/MSH pepudesto modulate learning and memory processes intoads. Supported in pan by the HHMIthrough the Undergraduate BiologicalSciences Education Pro cram.


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LOCALIZATION AND CHARACTERIZATION OFNEUROPEPTIDE Y/PEPTIDE YY RECEPTORS INTHE BRAIN OF THE SMOOTH DOGFISH(MUSTEL1S CANIS).D.C. McVcy", D. Rillichof, P.J. Mannon, anil S.R.Vigna. Duke University Marine Laboratory,Beaufort, NC and Duke University Medical Center,Durham, NC.

Multiple receptors for neurnpeptide Y (NPY)/peptide YY (PYY) exist in mammals, but little isknown about the evolution of this receptor. Salurablcbinding sites for '"i-porclne PYY were localized infrozen brain sections of smooth dogfish by radio-ligand binding and autoradiography. Binding wasspecific for PYY and related peptides and widely-distributed in the cerebral hemisphere cerebellum,and hindbrain, with high affinity (IC = 5 nni). Thespecificity of the binding site was analyzed usingcompetitive inhibition experiments with nunradio-actlvc NPY/PYY, and synthetic peptide analogsspecific for mammalian Yl and Y2 subtypes. Weconclude that a single receptor specific for the NPY/PYY family is expressed in smooth dogfish brainand that this putative NPY/PYY receptor resemblesthe mammalian Yl sub-type, suggesting that the Ylreceptor is the ancestral receptor in this family ofpeptides.

DIFFERENCES IN ANGIOTENSIN IIRECEPTOR BINDING CHARACTERISTICSBETWEEN TWO ANURAN SPECIES.W. Kloas and C.R. Propper." University ofKarlsruhe, Germany and Northern ArizonaUniversity, Flagstaff.

Angiotensin II (A-II) influences water balance invertebrates. Using autoradiography, we charact-erized the A-II receptor in kidney (glomeruli) andinterrenal tissue in two species of anurans. ForBufo marinus. the mean ± SD for the Bmax and K<jrespectively in the glomeruli was 44.39 + 6.35attomol/mm2 and 183.6 ± 15.6 pM. The interrenalvalues were 59.27 + 13.3 attomol/mm* and 183.8+ 17 pM. For Scaphiopus couchii. the Bmax andK<i values respectively in the glomeruli were 22.03± 5.72 attomol/mm2 and 530.8 + 126.45 pM andthe interrenal values were 11.47 ± 3.15 attomol/mm2 and 401± 59.5 pM. There were significantspecies differences in both Bmax and K<i values.BniM differences may reflect species differences inexpression of the receptor or different physiologicalstates at lime of tissue collection. In another studyin Xenopus. there was no expression of A-IIreceptor in interrenal tissue, despite the fact that theinterrenal morphological distribution is similar tothat of Scaphiopus. The different Kd values fromthis study suggest that some aspect of the A-II re-ceptor in these species varies. Furthermore, spec-ificity data demonstrate that these receptors differfrom the mammalian form. Supported by grantsDFG KL 745/2-2 to WK, IBN 93-10352 to CRP.

98 99

N-METHYL-D-ASPARTATE (NMDA)RECEPTORS IN THE BRAIN OFX1PH0PU0RUS. K.M. Flynn*, E.Y. Alter,S.P. Banerjee, and M.P. Schreibman. BrooklynCollege, CUNY and CUNY Medical School,New York.

The excitatory amino acid glutamate binds anumber of discrete receptors. The NMDA typeglutamate receptor in particular has beenimplicated in many neural functions, includingmodulation of the brain-pituitary-gonad axisthrough its action on gonadotropin releasing-hormone producing neurons. Using acceptedmethods for assaying receptors, we havedetermined the binding affinity of NMDAreceptors in whole brains of the platyfish,X. maculatus. We have shown that the bindingmaximum (Bmax) of the NMDA receptorvaries; sexually mature fish have a Bmax (5.1x 1O'M) more than twice that of younger,sexually immature animals (2.4 x lO"14). Ourdata indicate that sexually mature animalshave an increased number of NMDA receptorsor an increased affinity of the receptor for itsligand. This evidence suggests a role forglutamate in the regulation of maturity inXiphophorus. {Supported by PSC CUNY toS.P.B. and BARD (IS-2149-92) and NASA(NAGW-1704) to M.P.S.)

DISTRIBUTION OF COCKROACH-LlKJiALLATOSTATIN IN THE CNS OFDROSOPHILA.J.G. Yoon* and B. Stay. Univ. ofIowa, Iowa City.

A monoclonal antibody againstDjploptera punctata allatostatinwas used to localize cells in thecentral nervous system (CNS) ofDrosophila larvae and adults.Cockroach allatostatin inhibitsjuvenile hormone synthesis bycorpora allata in cockroaches andrelated insects but not in flies.Nevertheless extract of Droso-phila CNS, either larval oradult, inhibits cockroach corporaallata and numerous immunoreac-tive neurons are seen in thebrain and ventral ganglion ofDrosophila. A marked increase innumber of immunopositive motorneurons occurs in the adult.These include interneurons andnerves to visceral muscle as wellas endocrine midgut cells. Asexpected, nerves to corporaallata of Drosophila are notpositive to cockroach anti-allatostatin.

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A CONVULSANT LIGAND FOR THE GABAA

RECEPTOR COMPLEX ALTERS THYROIDHORMONE BINDING TO BRAIN MEMBRANES.J.V. Martin", D.B. Williams, K.C. Lee, G.W. Kalmus,R.G. Nagele and H. Lee. Biology Department,Rutgers Univ., Camden, NJ, East Carolina Univ.,Greenville and Univ. Med. & Dent, of NJ, Stratford.

While at least two sites for high-affinity bindingof [126lll3,3',5-triiodo-L-thyronine (I126I]T3) areknown to exist in brain membranes, the physio-logical significance of these binding sites is notcompletely understood. A convulsant (t-butylbi-cyclophosphorothionate or TBPS) which binds tothe K-aminobutyric acidA (GABAA) receptor complexwas tested for its effects on the binding of I'26I]T3

to brain membranes from adult male Sprague-Dawley rats. A membrane preparation wasrepeatedly washed by centrifugations andresuspensions in fresh buffer (1 mM MgCI2, 1 mMEDTA, and 0.1 mM dithiothreitol in 50 mM Tris-HCIbuffer, pH 8.0). Varying amounts of TBPS wereincubated with [125I)T3 and the washed membranesfor 30 min at 37°C in 50 mM Tris, 1 mM MgCI2, 1mM EDTA and 0.1 mM dithiothreitol, pH 8 0.Bound radioactivity was determined using afiltration assay. Lower levels of TBPS (10" M)increased binding of the radioligand above controllevels, while higher concentrations (10*** M) ofTBPS inhibited specific ['26I|T3 binding. Insummary, TBPS, a ligand for the convulsant site ofthe GABAA receptor complex, was found tomodulate the brain membrane binding of I125I]T3 in acomplex allosteric fashion.

ALLOSTERIC EFFECTS OF THYROID HORMONESON BINDING OF A LIGAND FOR THE GABAA

RECEPTOR COMPLEX.G.W. Kalmus', D.B. Williams, K.C. Lee, H. Lee andJ.V. Martin. East Carolina Univ., Greenville andRutgers Univ., Camden, NJ.

The effects of thyroid hormones on the GABAA

receptor complex of rat brain were studied using aligand for the convulsant site of the complex, [36lt-butylbicyclophosphorothionate (CSUBPS).Membranes were processed from a rat brainsynaptosomal preparation by freezing and thawingalong with repeated centrifugation and resuspensionin fresh 50 mM Tris HCI buffer with 1 mM EDTA(pH 7.4). Different concentrations of thyroidhormone were incubated with 2 nM I36S]TBPS, andaliquots of resuspended membranes in 50 mM TrisHCI and 250 mM NaCI (pH 7.4) for 90 min at 25°C. The incubates were rapidlyfiltered and washedtwice before radioactivity on the filters wasdetermined by liquid scintillation spectroscopy. L-triiodothyronine (L-T3) and L-thyroxine (L-T4) bothaltered |3SS1TBPS binding with biphasic dose-response curves. Each L-isomer of thyroid hormoneenhanced I36S]TBPS binding in the range of 10r Mand inhibited the binding at higher concentrations.However, neither D-isomer stimulated [3CS1TBPSbinding, although both had inhibitory effects in therange of 1 0 ' M. Neither reverse T3 nor tyrosineinfluenced [36S1TBPS binding. These data show astereospecific effect of thyroid hormones on theGABAA receptor complex of adult brain.

102 103

NEUROHYPOPHYSIAL PCPTIDIi CONTROL OFOVIDUCT CONTRACTION IN A CALCILIANAMPHIBIANCaryl A. Ililschcr *, Daniel J. Conklin, and Sunny K.Boyd. University of None Dame, None Dame, IN.

Neuroliypophysial peptides arc potent contraclois ofanuran and urodelc amphibian oviducls. Whcthci lliecaccilian (Order Gymnophiona) reproductive iracl is alsoresponsive to neuroliypophysial peptides has not beenexamined. Isolated oviduct rings of the viviparouscaccilian Typh/inici{c.\ //<//<»/> wcie exposed loncurohypuphysiiil pcplidcs and analogs, and changes intension were recorded. Arginine vasolocin was the mostpotent pcptidc in eliciting oviduct contraclionsSpontaneously oscillating and quiescent oviduct ringsshowed a dosc-dependent increase in oscillation amplitude,frequency, and baseline tension upon exposure to •irginincvasolocin, oxytocin, arginine vasopressm, fl'hc1, Oin*]-oxytocin (V, receptor agonist), and mcsolocin. Nocontractions were elicited upon exposure to [Deamino1,Val4, D-Arg'J-vasoprcssin (V, receptor agonist) or isoiocin.Anterior oviduct segments were more sensitive toncurohypophysial peptides and analogs, compared to caudalsegments. In oviparous amphibians, on the other hand, theposterior end of the oviduct is most sensitive. These datasuggest that the oviduct of T. nuium possesses a vasotocinreceptor similar to that of the mammalian V,-l> pc (pressor)receptor. Regional responsiveness of the oviduct lorc'Jrohjppphysia! pcptiJca ~a\ d'.is'cr 'ciMcxi ov'parjjsand viviparous species of .imphihiaiis. Suppnrted by Ni l !ur.nu R2'J-llI)24ti?.l

MOTIUTY CHARACTERISTICS OFSPERMATOZOA FROM MOUNTAIN SPINYLIZARDS, Sccloporus jcurovi.J.M. Matter*, S.S. Suarez and 1...I. Guillctlc, Jr.University of South Dakota, Vcrmillion, CornellUniversity, Ithaca. NY and Univctsily of Florida,Gainesville.

Mountain spiny lizard {Sccloporus /urrnvi) spermatozoaappear similar to other reptilian sperm; the head is elongatewith a helical twist and the entire cell is about 110 urn long.Mammalian spermatozoa characteristically exhibit increasedvelocities and flugcllar bending as they progress through themale reproductive tract. Increased motile activity takes placeas sperm near the fertilisation site. Scveial quantitativemeasures of molilily arc from vidco-nticiographic recordingsof S.jurrovi sperm in vino. Molility characteristics of spermare from three regions of male reproductive tracts (2cpididymal regions and vas defcrens) representing 7 adultliiards(n-3ol sperm). Two distinct l)pcs of molilily arcexhibited by torj sperm. "StraiglH"-swimming sperm havelinear traieclones with llagcllar beats that arc sinusoidal innature. "Tuinblc"-swimmim: sperm exhibit curvilineartra|cclories and flagcllac that arc locked in a bent position."Tumble" sperm exhibit greater velocities than "straight"spemi and are seen with greater frequency in posteriorregions of male reproductive tracts. Comparisons of spermmotilily characters (velocities and flagellar curvatures)between regions are not significantly different. Absence olmotilily differences may be related to prolonged periods olspem .storage tliut occur within females following


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EFFECT OF MATURING ADULT OVARIESON JUVENILE HOIWONE SYNTHESIS INLAST INSTAR MALE DIPLOPTERA PUNC-TATA.C.A. Stoltzman* and B. Stay.Univ. of Iowa, Iowa City.

The impact of maturing oocyteson JH synthesis by larval CA wasinvestigated using JH analog toinduce vitellogenin synthesis andoocyte development in Dialopterapunctata last instar males withor without implanted ovaries.Last instar males with implantedadult ovaries displayed completeoocyte development. JH synthesisin these male larvae was higherthan, but not significantly dif-ferent from, that of controls ondays when ovarian influence wouldbe expected. However, the matur-ing adult ovary in the analogtreated males resulted in moresupernumerary larval molts thandid analog treatment alone, indi-cating that the ovary did resultin increased JH. Therefore, adeveloping adult ovary increasedthe amount of JH in last instarmales, although significantdifferences in measured rateswere not detected.

DUAL EFFECTS OF PROGESTERONE ONPRODUCTION OF OTHER STEROID HOR-MONES BY FOLLICLES OF THE FROG, RANAPIPIENS.K.N. Smalley. Empona State University,Emporia, KS.

The primary steroid secreted by frog folli-cles changes from testosterone (T) to pro-gesterone (P) late in development. To investi-gate the mechanisms involved in thischange, follicles were dissected from maturefrog ovaries and incubated in vitro in thepresence of varying levels of P or 17cr-hydro-xyprogesterone (17-OHP). After incubation,the levels of T in the medium were measuredby RIA. At low doses (0-100 ng/ml) both Pand 17-OHP increased the production of T.This effect was enhanced by the addition offrog pituitary homogenate (FPH). However,at high doses (500 ng/ml) 1 7-OHP was up to20 times more effective than P in stimulatingT production, and P, in combination withFPH, reduced the secretion of T below thatseen with FPH alone. P also had a dual effecton estradiol secretion by younger follicles.The inhibitory effect of high levels of P couldplay a role in suppressing the production ofother steroids by mature follicles.

106 107

Ml.TAUOLISM IN ANTARCTIC SON COKAL.SM. Shl lcry, G.A Mines* and S.A. Walts Univcisilv olAlabama at Birmingham

Stcroidal compounds have been isolated Ironi and idcnulicdin various coiulhnc species, lislradiol has been delected inmass spawns (il tcinpcralc corals and cholcslciol has beenidcnLificd in scaualci surrounding polai soli coials, ho\\e\cr,ihcic is liulc inhumation concerning the ability ol corals tosynthesize stcroidal compounds. The alc\onanan Alrytmniinl»ic.ssk'ri and the stolunifcran Chlvithiria frnnklinitinti wcicjollcclcd Iroin McMutdn Sound, Antarctica dunng theirreproductive period. Whole body tissues ucic incubated with•^H-progcslcronc and -Vl-andiostcncdionc to determineMcioidogcnic capacity Tissues were oiganicall) extracted andsteroid metabolites were idcnulicd ul ih/jng T I X .dcrnali /ni ion, and rcei"\stalli/ation to constant spculicactiwty. Several slcroidal ioni|x>unds were s\i i lhcsi/rdindicating the endogenous picscncc ol stcioid metabolizingcn/.\mes in both species. Pioycsicmnc was com cried into 5<ipicgnanc-3,20-dionc, tcnlati\ cly, 5a-prcgncn- l7-ol-3.2(>-dionc. and an unidcnnlicd piogcMin ester AndioMcnedioncwas converted into primarily testosterone u ith lesserconversion into 5<<-andiosianc-3|>.l"7(t-diol, an unidciinliedandrogen ester and cpiandroslcronc in C.JrniiUinuuin. Bothspecies com cried piecuisoisat temperatures at least IO°Chigher than the expected range encoiiiilcd b\ these species.Although the compounds produced were similar to thoseidentified in .inutrclic cchinodcniis- and molluscs', eomcisionrates were substanliaJly Umcr toi both sol'i conil species,lindogcrams (Rl A-dclcrmincd) levels of progesterone andcMradiol wcic 12.3- 14.5 ng/g and 114- 131 pp/g.rcspccli\ c l \ , in w hole UHJ\ tissues ol A. pnt'A.\lcn. Theph\sio!ogical significance ol Ihc slcroidogcmc capacinexhibited by these organisms is nol knoun. Supported byNSF grants ' IDJ .B.M. and S.A.W.

DHI.AYHU OVARIAN DKVHI.OI'MHNT ANDREDUCED FECUNDITY IN LARGHMOUIHBASS RAISKD ON PHI .LKVHD FHEO.P. Rosenl>luni,'f H. Home, Ci. Garwood. T.Bntnclt and hi. Villaircal. Southwest Texas StaleUniv., National Biological Survey, and TexasParks and Wildlife Dcpt., San Marcos.

LargeinoiiIh bass were raised on forage or acommercially available pelleted feed whichcontained significanlly higher levels oftestosterone (T) and eslradiol-l7|; (H2), and lowerlevels of n-6 fatly acids than the forage fish.There was no diet-related diflcience in maximumgonaclosomalic index (GSI) reached, however,pcllct-fcd bass reached peak GSI I month laterthan forage-fed bass. Serum levels ol"V and 1-2were significantly suppressed during the periodof delayed ovarian growth in pellet-fed bass.Fatly acid analysis indicated decreased levels ofH-6 fatty acids (e.g.. arachidonic acid) in ovariesof pellet-fed bass. Fecundity was assessed in acontrolled raceway spawning experiment. Pellet-fed bass had significantly fewer spawns, andproduced fewer eggs and fry per spawn, than didforagc-lcd bass. Kgg viability (ferlili/alion andhatching rates) was not affected by diet. Delayedovarian development and reduced fecundity ofpcllct-fcd largemoulh bass may be due tonegative feedback effects of dietary steroidsand/or reduced levels of important fatty acids inovarian tissue.

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108 109REPRODUCTION IN THE DESERTTORTOISE: EFFECTS OF UPPERRESPIRATORY TRACT DISEASE.D.C. R o s t a l * , V.A. Lance, J . S .Grumbles, and I . Schumacher.Georgia Southern University,Zoological Society of San Diego,and University of Florida.

The effect of chronic upperrespiratory tract disease (URTD)on reproductive success wasstudied in the desert tortoise,GoptiBrus agassizii, at theDesert Tortoise ConservationCenter. Reproductive status offemales and egg production weremonitored by ultrasonography.Eggs were collected andincubated in the lab. Plasmatestosterone, progesterone,estradiol, and corticosteronewere measured. Clutch size, eggsize, hatching success, andhatcnling size were comparedbetween infected and healthytortoises. A negativecorrelation was observed betweeninfection and percent ofreproducing females. URTD maybe negatively affectingreproduction in wild tortoisepopulations.

ELEVATED FEMALE ANDROSTENEDIONE LEVELSIN TWO SEX ROLE REVERSED AVIAN SPECIES.A. F i v i z z a n i * , D. De lehan ty , L. Oring,P. Wrege, and S. Eralen. Univ. NorthDakota, Grand Forks , Univ. Nevada,Reno and C o r n e l l Un iv . , I t h a c a , NY.

The Wilson's phalarope Phalaropustricolor, and the wattled jacana,Jacana jacana are sex role reversed.Females aggressively compete Cor motesand play no role in incubation and avery minor role in care of young.Previous studies have indicated thatfemale aggressive behavior is notcorrelated with unusually elevatedlevels of plasma testosterone (T) orestradiol (E). In this studycirculating levels of androstenedione(A), along with (T) and (E), weremeasured by RIA in reproductivelyactive phalaropes and jacanas. Femalephalaropes possessed greater levels ofA than did males. Females hadsignificantly greater levels of Arelative to T than did males. Injacanas, A levels were comparablebetween the sexes. In the female Alevels were distinctly greater thaneither T or E. These results suggestthat androstenedione may play a rolein mediating aggressive femalebehavior in these sex role reversedavian species as has been reported forthe spotted hyena.

110 111

EFFECTS OF DOPAMINE, A DOPAMINERGIC AN-TAGONIST, AND A DOPAMINERGIC AGONIST ONTESTICULAR MATURATION IN THE FIDDLER CRAB,UCA PUGILATOR.M. Fingerman*, R. Sarojini, R. Nagabhush-anam, P.S. Reddy, and M. Devi. TulaneUniversity, New Orleans, LA.

The in vivo effects of dopamine (DA),a dopaminergic antagonist (spiperone),and a dopaminergic agonist (ADTN) on mat-uration of the testes in Uca pugilatorwere determined. The testicular indexand the mean diameter of the testicularlobes of crabs that received DA were sig-nificantly less than the correspondingvalues for the concurrent control crabs.ADTN also inhibited maturation of the tes-tes whereas spiperone induced testicularmaturation. These results provide thefirst evidence for dopaminergic inhibi-tion of testicular maturation in a crus-tacean. This DA-induced inhibition mayhave been due to: (a) inhibition of re-lease of the gonad-stimulating hormone,(b) stimulation of release of the gonad-inhibiting hormone, or (c) both (a) and(b).

IMMUNOCYTOCHEMICAL LOCALIZATION OF EN-KEPHALIN-LIKE MATERIAL IN THE GONADS OFTHE FIDDLER CRAB, UCA PUGILATOR.R. Nagabhushanam*, R. Sarojini, A. Mary,V. Mary, and M. Fingerman. Tulane Univer-sity, New Orleans, LA.

The presence of methionine-enkephalin-like and leucine-enkephalin-like immuno-reactivities in ovaries and testes of UcapuRilator was demonstrated by immunocyto-chemistry. In the ovaries immunoreactiv-ity to both enkephalins was seen in fol-licle cells in avitellogenic and earlyvitellogenic oocytes, but not in matureoocytes. In the testes immunoreactivityto both enkephalins was found in spermat-ogonia, spermatocytes, and spermatids,but not in spermatozoa. Although enkeph-alins are known to occur in crustaceanneurons, this is the first report of thepresence of enkephalin-like material inthe gonads of any crustacean. The pres-ence of enkephalin-like substances inthese gonads raises the possibility thatenkephalins are somehow involved in thecontrol of gonadal function in crusta-ceans.

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112 113

PITUITARY RESPONSIVENESS TO PERIFUSEDLAMPREY GNRH-I OR -III AND ANALOGS INTHE ADULT MALE SEA LAMPREY,PETROMYZON MARINUS.L. Gazourian* and S.A. Sower. Univcrsily of NewHampshire, Durham.

The objective of thus sludy was to examine litencurncndocrinc conirol of reproduction in the adultmale sea lamprey Peiromyion marinus by investigatingthe action of hypolhalamic lamprey GnRII-I or-111 onthe pituitary using an Acusyslcm-S mullipciifusionsystem. Indirect measurement of the pituitary responseto GnRII was accomplished by measuring csiradiolreleased from tcslcs sections which were incubated inthe pcrifusion effluent. In addition to native lampreyGnRll-1 or-III, seven lamprey GnRH analogs weretested to assess the ability ol the pituitary to distinguishbetween vananl forms of the molecule and to provideclues as to the structural requiifinenls at the lampreypituitary GnRI I receptor. Initial data .suggest thailamprey GnRI I-I acts on the pituitary to release asubstance capable of stimulating the Icstis. LampreyGnRI 1-1 or -III also demonstrated a direct, slightresponse on the icstis, suggesting the presence ofcxtrapituilary GnRI 1 rcccplors in the tcstcs. Thesiructurc-aclivily of the lamprey GnRII analogs withvarious substitutions in the sixth position suggest thatthe lamprey GnRII icccplor was capable ofdistinguishing between the variant forms of tlicmolecule. (Supported by NSF Grants DCB-89(W919and DCf5-9()(H332n and an undergraduate SURF toLG.)

LOCALIZATION OF IMMUNOKEACTIVE (IR)SOMATOLACTIN IN THE PITUITAKYGLAND OFXIPHOPHORUS. E.J. Yousha*, L.Magliulo Cepriano and M.P. Schreibman.Brooklyn College, CUNY, New York.

Somatolactin (SL), a glycoprotein in thegrowth hormone/prolactin family, has beenidentified in a number of teleosts where it wasfound primarily in the pars intermedia (PI), aregion of the pituitary gland rich in PAS+ cellsThe distribution of lr-SL (anti-cod SL; Dr. M.Rand-Weaver) and its relation to PAS+ cellswas studied in the pituitary gland of sexuallymature X. maculatus (platyfish). The greatestconcentration of ir-SL cells occurred in the PIwhere most , bu t not all , of theimmunoreactivity correlated with PAS+ cells.Some PAS+ cells did not contain ir-SL. Ir-SLwas also found in PAS negative cells in therostral pars distalis (RPD) among theadrenocorticotropes. Ir-SL was found lessfrequently in the caudal pars distalis (CPD). Ithas been hypothesized that SL plays a role inthe regulation of reproduction. A continuinganalysis of ir-SL distribution at differentdevelopmental stages inXiphophorus may helpto clarify its function.ISupported by NASA(NAGW-1704) and BAUD(IS-2149-92))

114 115

IN VIVO AND IN VITRO EFFECTS Ol; I.AMI'KEYGONADOTKOI'IN-RELEASING II0RM0NE-II1 INTHE ADULT SEA LAMPREY.K.L. Deragon* and S.A. Sower. University of NewHampshire, Durham.

Lamprey gonadolropin-rclcasing hormone-Ill(lamprey GnRH-III) was recently scqucnccd (Sower aal., 1993), and its putative role in reproduction has notbeen determined. Therefore, the objective of this sludywas to detenninc the in vivo and in vitro effects oflamprey GnRH-III in adult male and female sealampreys, Pctromyzon marinus, Preliminary studies onlamprey GnRH-III in female sea lampreys indicate thatlliis pcplidc may be a ncurohormonc involved inreproduction (Sower ct al., 1993). In the preseni sludy,injection of lamprey GnRH-III into adult male sealampreys increased levels of both progesterone andcstradiol, and induced spcrmialion. In vitro results inmale sea lampreys indicate that lamprey GnRH-III hasa direct effect on the tcsles. In female sea lampreys,injection of lamprey GnRH-III induced ovulalion andincreased levels of csiradiol and progesterone. Thesedata indicate thai lamprey GnRI I-III, similar tolamprey GnRII-1, is also a ncurohormonc involved inthe reproduction of the sea lamprey. (Supported byNSF Grants DCB-8904919 and DCB-90O1332, and anundergraduate NSF REU to SAS.)

SENSITIVITY OF CORPORA ALLATA TOALLATOSTATIN AFTER DENERVATIONAND JUVENILE HORMONE TREATMENT.S. Fairbairn* and B. Stay. Univ.of Iowa, Iowa City.

Allatostatins are neuropep-tides that inhibit juvenile hor-mone (JH) synthesis by corporaallata (CA) in insects. Sensi-tivity to allatostatin of CA froiradult male cockroach Diplopterapunctata was measured after sev-erance of nerves to the CA and/ortreatment of animals with JHanalog, (7S)-hydroprene. Resultswere expressed as percent inhi-bition of JH synthesis by 10"8Mallatostatin 1 in vitro. Inner-vated CA in animals treated withJH analog decreased in sensi-tivity. Denervation of CA re-sulted in delayed (after 4 days)increase in sensitivity, whereasdenervation of CA along with JHanalog treatment caused a rapidincrease in sensitivity of CA toallatostatin. Results suggestthat decreased paracrine releaseof allatostatin resulting fromdenervation of CA stimulatesupregulation of allatostatin re-ceptors and that elevated JHtiter enhances this effect.

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116 117THE ECDYSONE RECEPTOR (EcR) DURINGPROECDYSIS IN THE FIDDLER CRAB Uca pugilawrA. C.-K. Chung", D. S. Durica and P. M. Hopkins. Univ.of Oklahoma, Norman

During the proecdysial period of the crustacean moltcycle, ecdysteroid levels in the hcmolymph fluctuatesignificantly. Ecdysteroids coordinate many physiologicalevents which are important for ecdysis (molting). One of thephysiological events that occurs during proecdysis is the finalstage of regeneration of lost limbs. During proecdysis,regenerating limb buds complete growth and prepare formolting. During late proecdysis, apolysis occurs and freesthe old exoskeleton from the hypodermis. Following theseparation from the exoskeleton, protein synthesis increasesin the hypodermis and a new cuticle is secreted underneaththe old one. Using a heterologous anti-EcR monoclonalantibody (JG 6.2, gift of Dr. Hogness lab), temporalexpressions of ecdysone receptor (EcR) in hypodermis andlimb buds of fiddler crab Uca pugilawr during proecdysiswere examined. This antibody binds specifically to a 104amino acid region containing DNA-binding domain of theEcR protein. At least two bands showed positive responsesto this monoclonal antibody. These bands appeared inhypodermis and limb buds but their patterns appeared to bedifferent and tissue-specific. Moreover, there were morebands which showed positive responses to this antibody inhypodermis. The patterns of these putative EcR isoformswere correlated to changes in ecdysteroid levels ofhemolymph.

ECDYSTEROID SYNTHESIS INCRUSTACEANS: BINDING AND TRANSPORTOF LIP0PROTEIN-CH0LESTER0L BYY-ORCAN MEMBRANES.B.K. Rang and E. SpazianiUniv. of Iowa, Iowa City

Ecdysteroid hormones are formedfrom cholesterol in Y-organs ofcrustaceans, and all circulatingcholesterol is bound to high-dens,lipoprotein (HDL). Using 1-125-labeled HDL, uptake studies showedsaturation kinetics and energy-dependence. HDL was degraded bythe cells, also with saturationkinetics. These results indicatethat HDL is taken up intact, byreceptor-mediated, active endo-cytosis. Electron microscopyconfirmed endocytosis, throughcoated pits (shown with immunogold)With isolated Y-organ membranes,Lhe receptor was found to be oChigh capacity, high affinity type(Kd 1.08 x 10-7 M; B m a x 70 ug HDLprotcin/mg membr. protein). Uptakeand degradation were inhibited bymol t-inhibi t ing hormone (Mill),which actions were shown to be med-iated by cAMP and a decrease o£ 117.in no. of binding sites, but not inbinding affinity.

118 119

E X P R E S S I O N OF THE DIAZEPAMBINDING INHIBITOR (DBI) AND ANEW CYTOCHROME P4S0 IN THEPROTHORACIC GLANDS OF LARVALMANDVCA SEXTA. . Slcvcns, J.* and M.J.Snydcr. Univ of Arizona, Tucson.

Insect pro thorac ic glands produceecdysteroids that regulate molting andmetamorphosis. Despite the relative importance ofthis gland in Lcpidoptcra, little is known aboutchanges in the activities of specific gland proteinsthat may be involved in ecdysteroid biosynthesis.We examined the expression patterns of twoproteins during the first 9 days of the fifth instar.The first protein, the putative Manduca scxtadiazepam binding inhibitor (DBI) had the highestexpression of mRNA during days 2-4 beforedropping to barely detectable levels on days 6-9A new cytochromc P450 was identified on thebasis of sequence identity of a product resultingfrom PCR using degenerate primers. The newP450 is tentatively assigned to the CYP4 familyIts expression pattern included to peaks at days 2-3 and on day 5 of the fifth instar. Although thereare no data concerning the functions of these twoproteins it is tempting to speculate they may beinvolved in aspcct(s) of prothoracic glandecdysteroid biosynthesis.Supported by USDA grant #93-37303-9595.

CHARACTERIZATION OF A 1IKMOLYMPII FACl'ORTHAT STIMULATES METHYL FARNESOATE (MF)RELEASE H<0M MANDIHULAR ORGANS in vitro.D. J. Wilcox*. T. Clacrlioul, B. Tsukimura. and D.W. Borsl.Illinoi.s Suite Univ., Nonnal and Calif. Stale Univ , Fresno.

While (lie crustacean mandibular organ (MO) synthesizesMF in vitro, very little of (his product is released into theculture medium. In previous studies, we dcinonslralcd thatMF rclcn.se is stimulated by hcmolymph. To investigate thestimulation of MF release, we have partially characterized thehemolymph factor involved. MOs from Ubinm emarginatawere incubated in culture medium (CM, Ml99 modified withcrustacean nngcrs.) 311-mcUiioninc was added for 2 hours inlabel MF. MOs were then incubated for another hour in CMalone or supplemented wilii hcmolymph. In CM alone, theamount of MF released was low (~ 2%). When MOs wereincubated in CM and hcmolymph, MF release wa.s siunulaicdin a dose dependent way. For example, the addition of 2%hcmolymph caused 1% of the MF lo be released, whereas theaddition of 50% hemolymph caused 41% of the MF to bereleased. The hcmolymph factor was heat sensitive and didnot affect MF synthesis. Fractionation of hcmolymphproteins by gel filtration (Supcrosc 6) showed a broad peak ofactivity with a MW of approximately fiOO.000. Analysis ofthese fractions by gradient SDS-PAGE disclosed severalprotein bands (approx. sizes of 290, 250, 169, and 86 kDa).Releasing acuvity appeared to be associated with the 250 kDaband. Finally, the stimulation of MF release by hcmolymphcould be mimicked by bovine scrum albumin (BSA). BovinelgG had no effect. Since BSA and hcmolymph proteins bindMF but IjG doc* not, these data suggest that MF releasereflects liic picsenu: ut compounds lJi.it bind MF uSupporlcJby NSF Grant 1BN-931921)6).

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120 121

MOLECULAR CLONING OF A cDNAENCODING PUTATIVEMOLT-INHIBITINGHORMONE FROM THE BLUE CRABCALL1NECTES SAPIDUS.K.J. Lee*, R.D. Watson, and T.S. Elton.University of Alabama at Birmingham.Moll-inhibiting hormone (MIH), a peptideproduced by neurosccrclory cells in eyestalkneural ganglia, regulates ccdyslcroid secretionby crustacean Y-organs. A unidirectional cDNAlibrary was constructed in the Uni-Zap XRvector (Stratagene) using poly (A) RNA isolatedfrom eyestalk neural ganglia of Callincctcssapidus. Using primers based on the knownimino acid sequence of MIH from the shorecrab, Carcinus inacnas. a 169 base pair (bp)fragment of the MIH gene was PCR- amplifiedfrom C. macnas eyestalk cDNA. This fragmentwas cloned intoaTA-cloning vector, andsubsequently used to screen the C. sapid uscDNA library. Sequence analysis of one positiveclone revealed a 339 bp open reading frame anda 3' untranslated region of 1009 bp. The openreading frame encodes a 78 amino acid maturepeptide (putative MIH) and a 35 residue signalpeptide. The 78 residue peptide is 81 % and 27%homologous with MIH from C. macnas and thelobster, Homarus americanus, respectively.Supported by MS/ALSca Grant NA16RGOI55-03.

ENDOCRINE HYPOTHESIS FOR CONTROL OFSALMON SMOLTIFICATION.W. W. Dickhoh", B. R. Beckman, D. A. Larsen and S.Moriyama. Nat. Mar. Fish. Serv. and Univ. Washington,Seattle.

The parr-smolt transformation of anadromous salmonis influenced in part by photoperiod, temperature, andfood availability mediated through a multi-hormonalprocess that includes insulin, growth hormone, insulin-like growth factor-l, and thyroid hormones. Cydes ofactivation of these hormones during spring for mostspecies are annual events that are geneticallyprogrammed and entrained by photoperiod.Modulation of hormonal cycles by temperature andfood availability determine specific life history choices,e.g., residence as parr or migration as smolts. Studiesof both Atlantic and Pacific (coho) salmon have shownthat subsequent to the vernal hormonal cycles thegrowth potential of the juvenile fish becomes bimodal.Rapid growing fish are smolts, whereas slow growingfish remain as parr in freshwater or stunts in seawater.Recent studies of smolt development of Chinooksalmon have shown that physiological and behavioralmeasures of smoltification are enhanced by rapidgrowth during spring. These observations support anhypothesis that growth rate during the spring enhan-ces the parr-smolt transformation and determinessubsequent growth capacity. An endocrine model willbe presented to show pathways mediating photo-penodic and nutritional influences as well as points ofintegration of hormonal components.(Supported by Bonneville Power Administration,Projects 89-046 and 92-22; US Dept. Agriculture #91-37206-6822; Japan Society for the Promotion ofScience, and National Marine Fisheries Service)

122 123

POPULATION STRUCTURE AFFECTS HORMONEC H A N G E S IN A F A C U L T A T I V E L YMETAMORPHOSING SALAMANDER.L.J. Allison and J.P. Collins. Arizona State University,Tempc.

We tested the ability of population structure tocause variation between individual tiger salamanders incorticosterone and testosterone, two hormones known tomodify timing of metamorphosis. Interestingly, thosehormones arc associated with stress and growth, respectively,two factors related to variation in age at metamorphosis.Larvae were raised in high- or low-density populations infield enclosures with same-sized or larger animals. Highdensity and presence of same-sized animals caused highercorticosterone levels than low density and similartestosterone levels initially, but testosterone increased morein large animals during the experiment. Large animals alsometamorphosed with lower frequency. These hormonesdifferences will be discussed as they relate to predictionsfrom ecological models of metamorphosis.

THYROID HORMONE MEDIATION OF EMBRYONICDEVELOPMENT IN A DIRECT-DEVELOPING FROG,Eleuthcrodactylus coqiti.D.H. Jennings, and J. Hankcn.* Uziiversity of Colorado,Boulder

Thyroid hormones (TI I) piny a major role inmediating amphibian metamorphosis. We examinedembryos of the Puerto Rican direct-developing frog,Elcutltcroditclijlus coqui, to begin to assess the role of THin the development of an amphibian that lacks a free-living larval stage. The thyroid gland is histologicallyidentifiable midway through embryonic development;overall gland volume does not change substantiallyuntil after hatching. In contrast, colloid volumeincreases dramatically soon after the gland first appearsand then decreases rapidly before hatching. Theembryonic peak in colloid volume is followed by theremodeling of a number of tissues. The ontogeny ofTH receptor expression was examined byimmunocytochemistry using a polyclonal TH-reccptor-beta antibody. Receptor expression was found in anumber of embryonic tissues including cartilage,muscle, and gut prior to the differentiation of theembryonic thyroid. These observations are consistentwith the hypothesis that in the evolution of directdevelopment in amphibians, the endocrine mediationof metamorphosis in ancestral species has beenadvanced into embryonic development. Supported byNSF grants to J.H. and D.J.

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124 125THYROID HORMONES IN THE YOLK OFJAPANESE QUAIL EGGS.CM. Wilson* and F.M.A. McNabb. Virginia

Tech, Blacksburg.Maternal thyroid hormones (THs) in avian

egg yolk may be important in earlydevelopment prior to function of theembryonic thyroid gland. We have adapted amethanol/chloroform method for extractionof THs from avian egg yolk from a methodpreviously used by others to extract THs fromfish eggs and larvae. Methods were verifiedby demonstrating parallelism of seriallydiluted extracts in radioimmunoassays andby TH spike recoveries of 97.3, 100.1 and 98.3% in three trials. Extraction efficiency ofradiolabelled T3 added to homogenized yolkaveraged 50%, a value consistent with otherpublished uses of this technique. Yolk from10 eggs of different hens from a random-bredcolony contained 1.5 +/- .15 ng T3/g yolkand 3.3 +/- .14 ng T4/g yolk (mean +/-SE).These TH concentrations are similar to thosepresent in some tissues. These yolk T3s aresimilar to those in plasma but yolk T4 is lessthan in plasma. TH contents of different eggsfrom the same hen are relatively variable. THcontents of eggs do not vary in a simple waywith differences in hen plasma THconcentrations. Supported by a grant fromSigma Xi.

THYROXINE IN THE DESERT TORTOISE,Gopherus agassizii.K.A. Kohel', D.S. MacKenzie, D. Kostal, andV. Lance. Texas A&M Univ., Georgia SouthernUniv., and CRES, San Diego Zoological Society.

To characterize seasonal changes in thyroidfunction in a terrestrial reptile, thyroid hormoneswere measured over a period of two years indesert tortoises maintained at the Desert TortoiseConservation Center in Las Vegas, NV. In allsamples, triiodothyronine was nondetectable (lessthan 0.01 ng/ml). Thyroxine (T4) exhibiteddistinct cycles in both sexes, being lowest duringhibernation and rising following emergence.Females exhibited only one peak in T4, duringthe early spring. In males, T4 also peaked inearly spring but again in late summer. T4

increases correlated with periods of increasedfeeding, mating, and locomotor activity in springand increased male combat and mating in latesummer. Restricting food intake reduced T4 incaptive tortoises. Additionally, the late summerT4 rise in mature males was not found insubadult male tortoises held under identicalconditions. Thus, alterations in food intake andreproductive activity may serve to activateincreases in T4 production observed in wilddesert tortoises.

126 127

EFFECT OF TRIIODOTHYRONINE ONSURVIVAL AND GROWTH OF LARVALSTRIPED BASS {MORON'E SAXATMS)LHuang*, J. L Specker, and D. A. BengtsonDept. of Zoology, Univ. of Rhode Island,Kingston, Rl 02881 USA

Growth and survival of larval striped bassheld in 5 ppt seawater and treated withtriiodothyronine (T3) was measured at twostages. At 5 days after hatching, T3 at 100ng/ml and 50 ng/ml retarded the growth oflarval striped bass and caused a lowersurvival rate than that of 25 ng/ml and controltreatment. At 16 days after hatching, T3 at100 ng/ml retarded the growth of larval fishand caused a higher mortality. T3 at 10 ng/mland 1 ng/ml did not show any effect on eithersurvival or growth. The results indicate thatexogenous T3 can be detrimental to thegrowth and survival of larval striped bass.(Sponsored by R.I. Sea Grant)

5'-IODOTHYRONINE OUTER RINGDEIODINASE IN RED DRUM (Sciaenopsocellalus): CHARACTERIZATION ANDENVIRONMENTAL INFLUENCES.C.L.M. VanPutte*, D.S. MacKenzie and J.G.Eales. Texas A&M University and University ofManitoba.

Although 5'-deiodinase (5'-ORD) is crucial toactivation of thyroid hormones in manyvertebrates, it has been studied in relatively fewteleost species. We have characterized 5'-ORDin a warm water, rapidly-growing teleost, reddrum, to determine if the enzyme is similar tothat described for other species. Free iodideproduction varied with dithiothreitolconcentration, pH, incubation time and enzymedilution in a manner resembling other species.The Km remained relatively constant while VmI

varied among fish growing under differentconditions: Kra values ranged from 1.31 x 10' Mto 2.38 x 10"' M while V ^ values ranged from2.14 to 7.11 pmol T4 converted•hr'-mg protein'.Highest activity levels occurred in wild animalsassayed at warm temperatures and fish growingrapidly in intense aquaculture. Red drumdeiodinase therefore may be most active duringperiods of rapid growth ar.d high food intake.Funded by Texas Advanced Technology Program

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128 129SOMATOSTATIN, A MODULATOR OF INSULIN ANDGLUCAGON, SECRETION IS REGULATED BY LIPIDAND CARBOHYDRATE IN SALMONID FISH.N. M. Carneiro. C. D. Eilertson, and M. A. Sheridan*.North Dakota State Univ., Fargo.

Metabolite-somatostatin (SS-25) interactions werestudied by short-term infusion (2 min) of a triacyl-glycerol (TG)-rich lipid emulsion (20% Intralipid®) intorainbow trout {Oncorhynchuys mykiss) and by oralglucose challenge (167 mg/100 g body wt) of chinooksalmon (O. tshawytscha) acclimated for 63 days to eithera high-carbohydrate (HC; 28.7% carbohydrate) or lowcarbohydrate, LC; 18.5%) isocaloric diet. Hyperlipidemiawas induced following Intralipid infusion, with plasmatotal lipid increased 118% and 155% 1 h and 3 h,respectively, after infusion and plasma fatty acid (FA)increased by 39% and 520% over the same time-frameHyperlipemia resulted in a significant increase in SS-25,but did not affect plasma INS. Hyperlipidemia also didnot affect plasma glucose or tissue total lipidconcentration or the activity of the lipid mobilizingenzyme, TG lipase, in liver and adipose tissue. Glucosechallenge revealed that chinook salmon were glucoseintolerant; HC-acclimated salmon were less intolerantthan their LC counterparts (cf. Mazur et al., 1992 FishPhysiol. Biochem. 10:303-313). Plasma SS-25 levelsrose significantly in response to glucose challenge; theduration of the SS-25 increase was shorter in the HC-acclimated fish (6 h) than in LC-acclimated fish (12 h).These results indicate that lipids, principally in the formof TG and FA, and glucose are important regulators ofSS-25 secretion in salmonids. (Supported by NSF IBN9406707).

FISH GROWTH HORMONE STIMULATION OFSULFATION UPTAKE BY COMMON CARPBRANCHIAL CARTILAGE MAINTAINED INCULTURE WITH THE PRESENCE OF HUMAN IGF-IClara M. Cheng* and T.T. Chen.Center of Marine Biotechnology, UMBI ami Dcpl. ofBiological Sciences. UMitC, Ml)

Growth hormone is important in regulatinglongitudinal bone growth in all vertebrates. The action ofGH is believed to be mediated through insulin-like growthfactors (IGF-I and IGF-II). Extensive studies in mammalsrevealed that GH first stimulates the differentiation ofchondrocyle progenitor cells and increases theresponsiveness of these cells to IGF-I. IGF-I in lurnstimulates the further proliferation of these cells (DualEffector Theory). Although the actions of GH and IGF-I onbone growth in mammals have been worked out to a largeextent, their action mechanisms on growth regulation inteleosts await elucidation. Previous studies by otherinvestigators showed that while IGF-I stimulates in riiroincorporation of [35S]sulfatc into the telcostcan branchialcartilage, GH appears to be inactive in this aspect. Here,we have presented evidence to show thai tcleostcan GHcombined with low doses of human IGF-I or bovine insulinexhibits a dose-dependent synergistic stimulation of[35S]sulfate incorporation into the branchial cartilage of thecommon carp. To our knowledge, this is the first reportproviding evidence for a direct effect of Gil on sulf.itinnactivity in the tcleost cnitil.igc in vitin . The .syneigisnibetween GH and IGF-I strongly suggests the presence of a"Dual Effector mechanism" in teleosts.

130 131EXPRESSION OF TWO GROWTH HORMONE GENESIN RAINBOW TROUT (pmiv/iviiWiio m\ki\s).B.-Y. Yang* , N. C. Bols" and T. T. ChenCenter of Marine Biotechnology, UMBI, and Department ol

Biological Sciences, UMBC, Baltimore, MD Department oBiology, University of Waterloo, Ontario, Canada

Two different growth hormone (rlGH I and rlGH2) cDNAhave been detected in rainbow trout (Oncorhynclms mykiss)pituitary glands. By the use of reverse transcription andpolyincrasc chain reaction (RT-PCR) procedures, the level ofrlGHI mRNA is found to be five- to ten-fold higher than thatof rtGH2 mRNA in mature (two-years-old) females. One ofthe Irout GH genes, rlGH2. has been characterized earlier(Agcllon ct. al 1988). The second growth hormone gene,rtGH I, was isolated from a trout genomic library by using aPCR amplified intron V of rtGH I gene as a hybridizationprobe. The trout GH I gene spans a region of about 6 Kb and,similar to the rlGH2 gene, is comprised of six exons and fiveintrons. Nuclcotidc sequence analysis of the 5'-flankingregion of the rlGH genes reveals the presence of a stretch olsequences homologous to known mammalian glucoconicoidhormone and thyroid hormone response element sequences. Itseems likely that glucocorticoid hormone and thyroidhormone can directly control the expicssion of rtGH genes. Inorder to study the regulation of rtGHgcnes, we developed aGH-producing cell line RTP-2 from trout pituitary gland. Theeffects of thyroid hormone, glucoconicoid hormone, cslrogcrand relinoic acid on the expression of rtGH genes wereexamined at the mRNA level in the RTP-2 cells by usingcompetitive RT-PCR. Results of this study show thatdexamclhasone, 3,5.3'-triiodothyonine (T3) and cslradiol canincrease the accumulation of GH mRNA in the RTP-2 cells.

CLONING AND EXPRESSION OF TGF-BETA DURINGEARLY DEVELOPMENT OF FISH.B. Funkenstein*, B. Cavari and S.Jakowlew. (Introduction by E, Lubzens) .NCI, Rockville and Israel Oceanogr.Litnnol. Res. Inst., Haifa.

We have used degenerate oligonucleo-tides, designed on the basis of chickenTGF-beta3 cDNA sequence, to amplify afragment of 225 bp coding for part of themature TGF-beta protein. Sequence analy-sis of the PCR products obtained whenlarval RNA from the gilt head seabreamor carp were used, showed 73% and 81Zhomolosy,respectively, with chicken TGF-beta3 cDNA. Screening cDNA libraries pre-pared from the gilt head seabream andcarp larval RNA with the PCR productsyielded several positive clones. TheTGF-beta cDNA was used as a probe tostudy developmental expression of TGF-beta in fish eggs, embryos and larvae.

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Comparative Physiology & Biochemistry

132 133

CLONING AND SEQUENCING OF THE cDNA FORLIMULUS ARGININE KINASE. S.J. Strong* andW.R. Ellington, Fla. St. Univ., Tallahassee.

We have sequenced three full length clones ofthe gene for the fast isoform of arginine kinase(AK) from A.ZAP libraries of cardiac and skeletalmuscle from the horseshoe crab, Limuluspolyphemus. The gene consists of an open readingframe of 1,071 bases coding for a 357 residueprotein with a calculated Mr of 40,238 whichcompares well with the value of 41 kD forpurified fast AK (Strong & Ellington, JEZ267:563-571). The deduced amino acid sequenceis in accordance with amino acid sequencesdetermined for 6 LysC and 2 ArgC endoproteinasepeptides. The Limulus AK sequence displaysgreat similarity to lobster (76% identity) andabalone (54.4%) AK's. We have conductedmultiple alignments and sequence comparisons ofLimulus AK with available sequences for otherAK's (n=3), creatine kinases (CK, n=23) andglycocyamine kinase (GK, n=1). Extensiveregions of homology and similarity are evidentespecially in the internal regions (residues 30-350). Comparisons of consensus AK vs.consensus CK sequences revealed several sites,located in regions critical for catalytic activity,which appear to be unique to the particularphosphagen kinase. Furthermore, ourcomparisons have revealed some incon-sistencies with hypothesized roles of particularresidues in catalytic function.

OXIDATIVE ENZYME ACTIVITIES IN THENORTH AMERICAN PIKA, 0CH0T0NAPRINCEPS.Brandon A. Sheafor. University ofColorado, Boulder.Oxidativc enzyme activities were measured in fivetypes of muscle tissue (heart, diaphragm, vastus,gastrocnemius and soleus) in both the North Americanpika (Ocholona princeps) and Sprague-Dawleylaboratory rats. Pika are high altitude adaptedlagomorphs that inhabit the talus slopes above treeline throughout the Rocky Mountains. Laboratoryrats are assumed to be representative of a low altitudeadapted mammal. Citrate synthase (CS),hydroxyacylCoA dehydrogenase (HOAD), and lactatedchydrogenasc (LDH) activities/g of muscle tissuewere analyzed for all five muscle groups in both pikaand rats. Pika showed CS activities that weresignificantly higher than rats only in heart and vastustissues, suggesting that pika have merely a smallincrease in relative oxidative capacities whencompared to a low altitude adapted animal. HOADactivities were significantly higher in rat tissues thanin pika only in heart muscle, indicating that fatty acidoxidation is of less relative importance to pika than torats. Activities of LDH were significantly lower inpika heart, suggesting a reduced anaerobic capacityin this tissue. However, LDH activities weresignificantly higher in vastus and gastrocnemiusmuscle, indicating a higher reliance on anaerobicmetabolism in these muscles.

134 135

INTESTINAL NUTRIENT UPTAKE IN RED

DRUM.

S. Jordan, T.M Patterson and N.L. Collie'.

Texas Tech Univ., Lubbock

Sciaenopx ocellalus is a Gulf coastal marine

fish employed in our studies of dietary, endocrine

and intestinal adaptive interactions Here we

characterized the uptake patterns of glucose and 3

amino acids (Ala, Pro, and Lys) across the

intestinal brush border using an in vitro everted

sleeve technique. Like many carnivorous fish,

red drum exhibited high ammo acid uptake rates

that decline posteriorly along the gut. The

anterio-distal uptake gradient proved sharpest for

Lys, intermediate for Ala, and most gradual for

Pro. Surprisingly, glucose uptake increased

distally along the gut. The glucose uptake Vnm

and Km in the posterior intestine were,

respectively, 0.3 nmol/min • mg wet mass and 2.1

mM. In this gut region, glucose:pro uptake ratios

were more typical of those observed in

herbivorous fish. Hence red drum appear to be

proximal gut carnivores and distal gut herbivores

in their nutrient uptake pattern. Supported by

Texas Adv Tech Prog grant 010366-183

EFFECT OF AQUATIC FACTORS ON BULLFROGBRAIN GANGLIOSIDES.L.N. Irwin* and C. Tarango. University of Texas at ElPaso.

Bullfrogs (Rana caiesbeiana) occupy a greatdiversity of aquatic habitats over much of Norlh America.We have studied brain gangliosidc patterns as a possiblencurochcmical indicator of adaptability. Tadpoles werecollected from an acidic pond in Massachusetts and analkaline pond in Texas. Some larvae were exposed toincreasingly hypotonic water and increasing levels ofacidity. Analysis of gangliosicle profiles revealed litilcchange in these brain glycolipid metabolism remains stableover a large range of environmental conditions. Whetherthis stability has homeostatic relevance or is incidental tothe robust adaptability of this species in the next focus ofour research.

28A AMEF.CA\ SCCE"

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AN IMPROVED METHOD FOR PREPARATION OFCHANNEL CATFISH HEPATOCYTE CULTURESW. L.* Seddon and C. L. Prosser.Frostburg State Univ., Frostburg, andUniv. of Illinois, llrlicina..

An improved method has been developedfor isolating hepatocytes fro;:: livers ofchannel catfish. Hepatocytes areprepared using a collagenase-freeperfusior. system that relies on thechelating properties of EDTA. llepatocyteyields of up to 3.6 million cells perlOOg body weight have been achievedwith initial viabilities routinelyexceeding 95%. Cells isolated by thismethod and incubated in osmoticallycorrected L-15 medium at physiologicalpH have been maintained for severalweeks in culture with minimal cell loss.During the first 24-48 hr of culture,hepatocytes begin to link together andshow structures that closely resemblethose seen in intact liver (e.g. bilecanaliculi, sinusoids). Cultured cellsmaintain levels of G6PDII, 6PGDII, andLUII activity similar lo those measuredin vivo. Cell attachment, but notviability, enzyme activities, ormorphology, was enhanced by seedingcells onto culture dishes coated withMatrigel.Supported by NSF IBN 92-05007

HEMOLYMPH ECDYSONE AND ELECTROLYTESDURING THE MOLTING CYCLE OF CRAYFISH: ACOMPARISON OF NATURAL MOLTS WITHTHOSE INDUCED BY EYESTALK REMOVAL (ER)OR MULTIPLE LIMB AUTOTOMY (MLA).M. G. Wheatly* and M. K. Hart. Wright State Univ.Dayton, OH, and Univ. of Florida, Gainesville.

Hemolymph profiles for ecdysone and inorganicelectrolytes were used to compare the generalphysiological condition of crayfish Procambarusclarkii induced to molt by ER or MLA compared witha control group experiencing natural molts. Followingsurgery, ER crayfish underwent ecdysis sooner (13d)than MLA crayfish (36d). Ecdysone peaked around5d before ecdysis in control; in induced molts thispeak was protracted and double the concentration. Incontrol crayfish Ca was elevated 15d in advance ofecdysis. In MLA crayfish the Ca peak occurredearlier and in advance of the ecdysone peak; apremolt peak was not observed in ER crayfish. MLAcrayfish exhibited similar Na and Cl profiles tocontrol crayfish. Levels of all electrolytes in ERcrayfish at ecdysis were significantly reducedindicating excessive water influx. These molts wereroutinely fatal indicating that the eyestalks containfactors that regulate water and electrolyte balance.Sufficient differences between profiles in MLA andcontrol crayfish indicate that the two are notphysiologically or metabolicaHy equivalent.Supported by NSF grant 8916412.

138 139

PHYSIOLOGICAL CONfPETENCE THROUGHDEVELOPMENT OF ROMALEA TO CORPORACARDIACA PREPARATIONSHatle, J.D. and J.H. Spring University ofSouthwestern Louisiana, Lafayette

Romalea were tested at several developmentalstages for competence to factors from the corporacardiaca (CC) by assays of hemolymph lipid,hemolymph carbohydrate, and glycogenphosphorylase activation. Dosages used (0.1 CCequivalents) were known from previous reports(Spring and Gade, 1989) to be 10-fold higher thannecessary to elicit maximal responses. Treatmentwith CC preparations produced a consistentlyhypolipemic effect, i.e, hemolymph lipidsdecreased significantly at each stage ofdevelopment. Hemolymph carbohydrate levelswere unchanged upon CC treatment in alldevelopmental stages except fifth instars, in whichcarbohydrates decreased significantly. Fat bodyglycogen phosphorylase was activated significantlyby CC treatment in instar 5, second week, and thirdweek adults, whereas third and fourth instars andnew adults showed no change in fat body glycogenphosphorylase activation with CC extracttreatment. Supported by USDA grant 9301639 toJHS.

STUDIES ON MACROPROTEIN ABSORPTIONBY THE INTESTINE OF STRIPED BASSI.M0R0NE SAXATILIS) LARVAE USINGANTISERA TO ARTEMIA LIPOVITELLINS.M. Kishida*, K. Johanning, J.L.Specker and D.A. Bengtson. Univ. ofRhode Island, Kingston.

Striped bass larvae at 15 daysof age were fed with live Artemianauplii, and sampled after 2, 4, 8,and 12h. The fish were analyzed byimmunocytochemistry using antiserato Artemia lipovitellins. Noprotein absorption was observed inthe anterior intestine. However, inthe posterior intestine, positivelystained vesicles appeared near theapical membrane (2h), andsupranuclear vacuoles positivelystained were developed (4h). At 8h,the vacuoles near the tip of themucosal fold appeared lessimmunoreactive, but those at theside of the fold remained positive.At 12h, more vacuoles lost thereaction. The results demonstratedthat the posterior intestineabsorbs macroproteins contained inthe Artemia, which has beenconsidered as a required feed forstriped bass larvae. (Supported byUSDA Grant 92-37206-7848)

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140 141

EXPERIMENTAL MANIPULATION OF EGGQUALITY IN CHICKENS: INFLUENCE OFEGG COMPOSITION ON EMBRYO ANDHATCHLING SIZE.

M.S.* FINKLER and J.B. VAN ORMANand P. R. SOTHERLAND. KalamazooCollege, MI.

A fraction of the albumen or theyolk was removed from chicken eggsbefore they were incubated toinvestigate how eaqh of the eggcomponents influences body massand yolk sac mass of near-termembryos and hatchlings. Removal ofalbumen resulted in a decrease inwet body mass, corresponding todecreases in water content in thebody and yolk sac. Removal of yolkresulted in no change in wet bodymass, but in decreases in both wetand dry yolk sac mass. Albumen,which is composed of about 90swater, is the main determinant ofhatchling mass, and may representa low-cost means by which femalesinvest in the success of theiroffspring.

CHANGES IN THE LIPID COMPOSITION OFLAMPREY, PETROMYZON MARINUS, DURINGMETAMORPHOSISY. H. Kao", J. H. Youson2, and M. A. Sheridan1. 'NorthDakota St. Univ., Fargo; 'Univ. Toronto, Scarborough.

Lamprey development includes a metamorphicepisode which transforms microphagic filter-feeding larvainto either nonparasitic or parasitic adults, depending onspecies. This study examined alterations in the lipidcomposition of the parasitic lamprey, P. marinus, duringits 7 stages of metamorphosis. In larva, lipid waspredominately stored in kidney (nephric fold; 491.8 mglipid/g fresh wt) and to a lesser extent in liver (71.38mg/g) and intestine (17.06 mg/g). Duringmetamorphosis, lipid was significantly depleted fromkidney and liver (total lipid decreased 61.2% and 36.3%,respectively); however, lipid accumulated in intestine(91.4%). Most of the decline in kidney lipid was astriacylglycerol (TG), but significant diminutions incholesterol (C) content also were observed.Fluctuations in the lipid class composition of liver andintestine also were noted, principally in the phospholipidand C classes. While TG content increased in intestine,no change in the amount of this component wasobserved in liver. The amount of saturated FA declinedduring metamorphosis, whereas the amount ofunsaturated FA increased. These data indicate thatkidney is the principal lipid storage site of larval P.marinus and that significant alterations in lipidmetabolism occur during metamorphosis, includingmobilization (from kidney) and partial redistribution (tointestine). (Supported by NSF IBN 9406707 to M.A.S.and Great Lakes Fisheries Commission to J.H.Y.)

142 143

WATER LOSS AND METABOLIC RATEDURING FLIGHT IN THE BEES CENTIUSPALUDA and APISMELLIFFJiA.S.P. Roberts*, N.F. Hadley and J.F. Harrison,Dept. of Zoology, Arizona State University,Tempe, AZ

Insect flight is typically associated withhigher metabolic and water loss rates (WLR),the latter resulting presumably from increasedrespiratory transpiration.' In C. pallicla and A.mcllifera, flight CO2 emission rates (VCO2)increase dramatically (17-52X) over restinglevels at all ambient temperatures (T,).However, flight VCO2 decreases at higher T,. Incontrast, flight WLR, which are 4-6X those ofresting bees, increase at high Ta. WLR ofdead, sealed bees suggest that cuticulartranspiration accounts for 25-50% of flightWLR, with the contribution of cuticulartranspiration to flight WLR increasing athigher Tn The reduced metabolic rates athigher T, may help the bees preventoverheating and conserve water under aridconditions.

EFFECTS OF SOIL TEMPERATURE AND MOISTUREON HETEROZYG0SITY-GR0WTH RELATIONSHIPSIN THE EARTHWORM EISENIA FETIDA.M.L. Presley*, T.C. McElroy, M.C. Audoand W.J. Diehl. Mississippi State Univ.,Starkville.

Stressful environmental conditionspromote multilocus heterozygosity (MLH)-growth relationships in many species.The interactive effects of temperatureand soil moisture on MLH-growthrelationships in E_. fetida were examinedin earthworms grown for 2 weeks in allcombinations of 20°C & 25°C and 2, 3, &4 ml H2O/g dry peat moss. KLH wasmeasured for 8 polymorphic loci bystarch-gel electrophoresis. In the 20°Ctreatments, growth was not correlatedwith KLH, regardless of moisture. In the25°C treatments, growth was correlatedrfith KLH in the 3 ml/g (P<0.0l) and 2ml/g (P<0.05) treatments but not in the4 ml/g treatment. Moisture affected KLH-growth relationships only at temperaturesnear the upper thermal limit for thespecies. At these temperatures, moderatesoil moisture produced stronger IXU-growth relationships than low or highmoisture. Thus environmental quantityand quality interacted to affect tfLH-growth relationships. Supported by NSFrer.t 7"2-922'C9i to "JO.


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EFFECT OF GLYCEROL 3-PHOSPHATEDEHYDROGENASE GENOTYPE ON GROWTH,SURVIVORSHIP AND FECUNDITY IN THEEARTHWORM EISENIA FETIDA.'T.C. McElroy*, K.L. Presley and W.J.Diehl. Mississippi State Univ.,Starkville.

Gpd2 encodes an isozyme of glycerol3-phosphate dehydrogenase that plays arole in heterozygosity-growthrelationships in E_. fetida. The effectof Gpd2 on fitness (weight, mortality,fecundity) was examined'in earthwormsraised to asymptotic weight (50 wks @20°C, 3 ml H2O/g peat moss). Genotypeswere assayed by starch-gelelectrophoresis. The populationcontained a fast allele (F, freq = 0.38)and a slow allele (S, freq = 0.62).Throughout the experiment, the weightsof F/S heterozygotes and F/F homozygoteswere similar and were greater than Lhatof S/S homozygotes. The survivorships ofF/S heterozygotes and S/S homozygoteswere similar, and by week 12, weregreater than that of F/F homozygotes.There was no effect of genotype onfecundity. No homozygous genotype wasconsistantly more fit than the otherhomozygous genotype, but heterozygoteswere as fit as the most fit homozygousgenotype. Supported by NSF grant DEB-9221094 to WJI).

ALLOZYME VARIATION IN A PATCHILYDISTRIBUTED POPULATION OF CROTAPHYUSCOLLARIS.J.M. Hranitz* and T.A. Baird. Dept. Biol., Univ.Central Ok.. Edmond, OK 73034.

At Arcadia Lake Dam, Oklahoma, collared lizards(Crotanhvtus collaris) occur on three patches of rockyhabitat that are separated by uninhabited areas overwhich individuals rarely traverse. Individuals of bothsexes exhibit a high degree of lifelong patch fidelitysuggesting that these may be genetically differentdemes. To examine this hypothesis, we determinedgenotypes at 11 enzyme loci for 49 lizards occupyingthree patches in central Oklahoma. Nine loci werepolymorphic in the population, while two (Grid, Lap)were monomorphic. Polymorphism (P=0.727-0.818)and mean heterozygosity (A=0.218-0.327) in lizardsfrom the three patches were greater than previouslyreported values for these same loci in Crotanhvtus.No significant deviation from Hardy-Weinbergexpectations was observed at the nine polymorphic lociwithin patches except at the Alat locus on one patch.Significant variation in allele frequencies amongpatches occured at one locus (G6pd. j(2=6.205, df=2,P=0.044), although the overall outcome obtained bypooling all loci showed no spatial variation in allelefrequencies (x2=23.667, df=18, P = 0.166). Eithergene flow (Nm*4) among habitat patches compensatesfor the effect of lifelong patch fidelity, or significantgenetic divergence among patches has not occurredsince this population was established in 1986.

146 147

EFFECTS OF GENETICS AMD SIDESTREAMSMOKE ON SURVIVORSHIP OF THREE IN-BRED STRAINS OF MICE. C. E. Mays*,K.M. Mishler, V.U. Rao, and A.L.Matis. DePauw University, Green-castle, IN.

The effects of genetics (strain)and environment (sidestream smoke)on pup survivorship of three in-bred strains of mice were examinedby the use of crosses and back-crosses. Parental generationcrosses of BALD/c (B), C3H/6 (3),and C57BL (C) strains producedsignificantly different (P<0.01)mean survivorship values. Hetero-sis resulted from ExC crosses andbackcrosses. Survivorship patt-erns of inheritance of smoke-exposed mice are similar to thoseof the respective control mice;however, pup survivorship of Ex3experimental crosses with 25% BALB/c genetic character appears to bedue to epistasis. Pups of dams con-tributing BALB/c genes tend tosurvive better than those producedby either C3H or C57BL dams. Two-way analysis of variance and chis-quare analysis showed that geneticcharacter and sidestream smokeaffected mean survivorship.

EVAPORATIVE WATER LOSS AND CORPO-RAL TEMPERATURE IN SYMPATRIC FIDD-LER CRABS (UCA).C.L. Thurman, University of North-ern Iowa, Cedar Falls.

Desiccation and thermal stressare primary factors limiting ter-restriality in crustaceans. Waterloss was estimated as weight changein five species of Uca from southTexas for periods up to 7 hr. Cor-poral temperature was estimatedwith copper/constantan thermocoup-les placed under the carapace. Inall species, most rapid weight lossoccurred in the first 5 mn of expo-sure to dry air while body tempera-ture fell below ambient (25°C). Thethree most terrestrial species ex-hibited significant survival overthe aquatic after prolonged desicc-ation. Greatest rates of water losswere observed in U. subcvlindrica.It lost 22.9+3.0% bw. U.panacea andU. spinicarpa lost 14.1+1.6% and18.5+1.8%bw, respectively. Thissupports the notion that water losscan effectively lower body temper-ature in fiddler crabs. Ultimatelyboth physiological and behavioralmechanisms aid in adaptation to thesemi-arid habitats in south Texas.

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148 149BEHAVIORAL THERMOREGULATIONINCREASES GROWTH RATE IN ANOCTURNAL LIZARD. K. Autumn andD.F. de Nardo. Univ. of California, Berkeley.

We tested the hypothesis that thcrmoregulationincreases growth rate in nocturnal lizards. Leop-ard geckos (Eublcpharis macularius) maintainedfrom hatching at 25°C grew at a rate of 0.11g/day, while geckos allowed to thermoregulate atpreferred body temperatures (30°C for 13.5 h perday) grew 1.5 times as fast (0.16 g/day). Long-term thermal treatment had a significant reverseacclimation effect on preferred body temperature(Tp): Tp was 1.2°C lower in thennoregulatoryindividuals than in those kept at 25°. Feeding andrime of day also had significant but minor effectson Tp. Despite their nocturnal ecology, leopardgeckos seem to be typical among lizards in re-quiring a diurnal heat source for maximal growth.This result provides a physiological explanationfor the observation that some nocturnal lizardsthermoregulate in burrows during the day, andmay have implications for the biogeography ofnocturnal ectotherms.

PHYSIOLOGICAL AND BEHAVIORALRESPONSE OF THE TADPOLE SHRIMPTRIOPS LONGICAUDATOS TO HY.POXIA.David A. Scholnick. University ofColorado, Boulder.

Tadpole shrimp, Triops longicaudatus live inextremely variable oxygen environments.Water oxygen tensions can vary from 30 to250 torr with each diel cycle. When wateroxygen tensions are low, Triops makenumerous trips to the surface in order torecharge hemolymph with oxygen. This studyinvestigated the influence of hemoglobinconcentration on time spent diving in hypoxicwaters and the effect of dive time on growthrate. It was determined that hemolymphhemoglobin concentrations are inverselyrelated to the oxygen tension in which animalsarc raised and are positively correlated withthe amount of time spent diving duringhypoxia. Individuals that were allowed tomigrate to the surface during hypoxia hadhigher growth rates than those that wereprevented from utilizing high oxygen surfacewaters. Extracellular hemoglobin in Triopstherefore functions to maximize diving time inhypoxic waters which has a significant effecton growth and potential reproductive success.

150 151PHYSIOLOGICAL & BIOCHEMICAL CHANGESASSOCIATED WITH CONSTANT HYPOXIGEXPOSURE IN THE GULF KILLIFISHFUNDULUS GRANDIS.Rebecca Selbel*. W. B. Stickle and Tapash Das.Louisiana State University. Baton Rouge.

Physiological and biochemical changes ofF. grandts to hypoxia were monitored for 28 d at23°C and 30°/.. S. F. grandls were exposed tonormoxla (155 torr OJ and constant hypoxiclevels (115. 90. 50. 25 and 0 torr OJ. Fish weremonitored for survival, RNA:DNA andProteln:DAN ratios. F. grandls were found towithstand prolonged hypoxia with a 28 d LCJO of28 torr. All the fish died within 2 d under totalanoxia. Surface- breathing was observed in allanimals as was an apparent accumulation ofmyoglobln around the mouth and gills.Deployment of a "false celling" which preventedsuch breathing significantly reduced their abilityto tolerate hypoxic water. The RNA:DNA ratio ofliver dropped considerably at 50 torr O2

saturation compared to the control. A parallelexperiment indicated that they are not able tosurvive starvation past 21 d.The ratios ofRNA:DNA and Proteln:DNA also declinedconsiderably in the white muscle after 14 d ofstarvation.

PHYSIOLOGICAL & BIOCHEMICAL CHANGESASSOCIATED WITH ENVIRONMENTAL STRESSIN THE GULF KILLIFISH FUNDULUS CRANDIS.Tapash Das. Rebecca Selbel and W. B. Stickle*.Louisiana State University. Baton Rouge.

F, grandls is exposed to dlel variation inO2 saturation in the estuaries along the Gulf ofMexico especially during the summer months.Ambient oxygen was varied In the water In asinusoidal manner over the 24 hr periodbetween 100% and 16% O2 saturation. F.grandls was exposed to dlumally varyinghypoxic water for 28 d and monitored forsurvival and changes in the RNA;DNA andProteln:DNA ratios. Survival was not affected bythe dlel variation in O2 saturation. RNA:DNAratio in the white muscle and liver did notchange significantly over time. We alsoinvestigated the effects of starvation on a groupof killlfish for 28 d. F. grandls did not survivestarvation beyond 21 d. The RNA:DNA ratio ofwhite muscle dropped considerably afterstarvation for 14 d. F. grandls can toleratechronically low oxygen for a prolonged period(28 d LCso 27 torr O2. Seibel et al 1995) and areprobably able to avoid hypoxic water masses.Therefore, dlel variation in the oxygenconcentration during the summer months doesnot severely retard their anabollsm.


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152 153BILATERAL RESPIRATORY RESPONSES TOACUTE HYPOXIA IN THE AMERICAN LOBSTER.K. Trump, A. Aude, M. Leonard and D.Jorgensen*. Roanoke College, Salem, VA.

Lobsters have a gill set enclosed in each of twoseparate branchial chambers located on either sideof the thoracic region of the animal. Each branchi-al chamber has its own exhalant opening locatedanteriorly just lateral to the mouth. We havedevised a means to collect exhalant water issuingfrom each gill chamber so we could assess func-tion of the two gill sets separately in lobstersbefore, during and after acute hypoxic exposure.Acrylic masks were fitted over each exhalantopening (enclosing all mouth parts except the 3rdmaxilliped) and secured to the carapace. An elec-tromagnetic flow probe was placed in an openingat the apex of each mask to monitor ventilationrate. Catheters inserted into each mask allowedsampling of exhalant water for pO2 analysis. Undernormoxic conditions, the function of the two gillsets was mismatched with ventilation rate on theright side exceeding that on the left side by about2-fold. The contribution of the right gill set to totaloxygen uptake was 65-70%. During hypoxicexposure the extent of functional mismatch of thetwo sets decreased, approaching 50% contributionto total oxygen uptake by each set. Oxygen ex-traction on the two sides remained relativelymatched. The functional mismatch we observedhas implications regarding perfusion of the gill setswith hemolymph.

CHLORIDE, SODIUM TRANSPORT AND THELOSS OF TITRATABLE BASE IN THEFRESHWATER BIVALVE, CORBICULAFLUMINEA.H. Zheng* and T. H. Dietz. Louisiana StateUniversity., Baton Rouge.

The effects of serotonin and acetazolamidein the presence or absence of Na and Cl,respectively, on Q and Na transport, and netflux of titratable base in freshwater C. flumineawere investigated. Serotonin was found tostimulate both Cl and Na transport byincreasing the influx with no effect on theefflux. Acetazolamide was demonstrated toinhibit Cl transport by increasing the efflux to agreater extent than the small but significantincrease in influx. AZ stimulated Na effluxwithout a change in Na influx. Both serotoninand acetazolamide increased the net loss oftitratable base significantly. Cl and Natransport were independent in the presence orabsence of serotonin. The net loss of titratablebase increased significantly in the absence ofexternal Na, but was not affected by theabsence of external Cl in both pondwater andsalt depleted animals, suggesting that Cl"/HCO," exchange is not a major way forHCO, exit in C. lluminea. Supported by NSF90-17361.

154 155

THE EFFECTS OF SALINITY ON ZEBRAMUSSEL (Dreissena polyinorpha)OSMOREGULATION AND MORTALITY.Wilcox, S.J. and T.H. Dietz. Louisiana StateUniv., Baton Rouge.

The effects of elevated ion concentrationon osmoregulation and mortality rate wereexamined in the freshwater bivalve Dreissenapolymorpha. Animals acclimated to 100 mOsm(diluted artificial seawater, ASW) and exposedto a 10-100 mOsm/day increase uniformlytolerated the osmotic stress up 300-400 mOsm,after which mortality increased. Independent ofthe exposure interval, the upper lethal tolerancelimit was 500-650 mOsm. Total soluteconcentrations in the blood of animalsacclimated for at least a week in dilute ASWwere isosmotic to the bathing medium. Areduction in the solute concentration of the bathover an 8h period (final concentrationapproximating freshwater) resulted in decreasedtotal solute concentrations in the blood at a rateequal to but approximately 2-4h behind that ofthe bathing medium. Animals exposed to asimulated freshwater/seawater tidal cycleexhibited a characteristic elevation or loss ofblood ions correlated with the soluteconcentration of the bathing medium.Supported by NSF 90-17461.

OSMOREGULATION AND Na, K-ATPaseACTIVITY IN THE GILLS OF THE THAICRAB, Pseudosesanna moeschi.R. McLaughlin and C.W. Holliday^ LafayetteCollege, Easton, PA.

Pseudosesarma moeschi osmorcgulates well inthe salinity range 5%-100% seawater (SW, 100%= 1000 mOsm); it hyperrcgulates in dilute media,hyporegulates in more concentrated media and isisoosmotic in 60% SW(600 mOsm). As in othereuryhaline crabs, the posterior gills (#4-#6) havemuch higher Na, K-ATPase enzyme specificactivity (ESA) than the anterior gills (#l-#3).Further, the ESA of posterior gills was minimalin crabs acclimated in SW media in which theyare nearly isoosmotic (50% and 75% SW). Incrabs acclimated in 5% SW and transferred to50% SW, the time course of deactivation of Na,K-ATPase is consistent with both short-termmodulation of the activity of existing enzyme(i.e., hemolymph osmotic pressure is nearlyconstant) and long-term (4-6 days) inactivationof enzyme in the posterior gills. Thus, as in mostosmoregulaling crabs, the posterior gills seem tobe specialized for osmoregulatory ion transportin P. moeschi.

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156 157siuris IN TIN: I:RI;I; AMINO ACID POOL OI: APRHSII-WATI-R GRASS SHRIMP liXPOSI-IJ TOSALINITY CHANGE.N'.L. Caris. Texas A&M Univ., College Sialiun.

In Ihc face of changing salinity, curyhalinc invtitcbralesmamlain a homcosialic cell volume by regulating theconcentration of intraccllular solutes including Tree non-csscntial amino acids This study examines how the freeamino acid pool (l-"AA) ol 'a fresh-water grass shiimp,I'cilaeinoticlL's kuditikcMi*. responds to changes in salinity.Glycinc was the most abundant jmino acid comprisingover 50% of the total pool in salinities above o/oo TotalP'AA, gljcine, glulamale and aspailic acid concentrationsincreased with increasing salinity Concentrations of theother non-essenlial amino acids (prolinc, aiginme.glutaminc, alanine and asparagine) were highest at 24o/oo Aspaitic acid was the only ammo acid thatsuccessively increased in percentage of the total pool. /'kucliukemii was able to loleiale salinities up to 24 o/oobecause of the well developed capacity for couuollinginlraceilular PAA concent)atiou. This may he a icmnantfrom ils brackish water ancestry. Slcnohaline frcsh-watcrspecies with a long history in I'resh w.itcr usually lo.sesonic capacity lor intraccllular nmsosmotic regulationHigh hcmolymph chloride and osmotic concentiations andproduction of an isosinotic urine, support the contentionlhal P. kiidiukcnsi\ is a recent invader into IVcsh water.

NMR SPECTROSCOPY OF NITROGEN

COMPOUNDS IN NEAR TERM SMOOTHDOGFISH MATERNAL AND FETALTISSUES.C.R. Graham, Jr. Loyola College in Maryland,Baltimore

The most ubiquitous non-protein, nitrogenouscompounds in elasmobranch body fluids are urea,TMAO, betaine, and amino acids. Many of thesecompounds play major roles in osmorcgulation.Other recognized roles for nitrogen containingcompounds include; cryoprotection, antioxidation,positive buoyancy, chelation, and protectionagainst protein denaturation. Carbon-13, highfield NMR spectroscopy can effectively be usedto identify organic compounds present in millimolar concentrations and to recognize relativeconcentration changes of specific compounds indifferent samples. In this report, NMR spectra areused to characterize the distribution and relativeconcentrations of urea, TMAO, taurinc, alanine,and betaine in samples of maternal blood plasma,uterine fluid, umbilical blood plasma, fetal bloodplasma, egg capsule fluid, and fetal stomach andspiral valve contents taken from a single, nearterm smooth dogfish shark.

158 159

RESPONSE OF AMPHIBIAN GASTRIC MUSCLE TOOPIATE RECEPTOR AGONISTS.A. Gonzalez®*, M. Rubio-Davila, I. Torres and G.Escalona de Motta. @Dept. of Pharmacology, Univ. ofCartagena, Colombia, and Dept. of Biology andInstitute of Neurobiology, Univ. of Puerto Rico, SanJuan, 00901.

Opiates are known to mediate activities in vertebrateenteric muscles. Using immunolluorescence methodswe detected an Enkephalin-like reactivity inmuscularis muscle strips dissected from Rana pipiensstomachs. Spontaneous phasic contractions in thesemuscles, recorded isometrically, were determined tobe mediated by muscarinic cholinergic receptors.Effects of different opiate receptor agonists on thesecontractions were examined in pharmacologic studies.DAGO, a mu agonist, increased the force andfrequency of contractions whereas Met-Enkephalin, adelta agonist, decreased the contraction force.Dynorphin-A, a kappa agonist, had no apparent effecton this muscle. The antagonist Naloxone did not affectthe spontaneous activity nor altered the responses toDAGO. However, Dynorphin-A decreased the force ofcontraction of Naloxone-treated muscles andenhanced the muscle contractions inhibited by themuscarinic blocker Pirenzepine. Thus, mu, delta andkappa opioid receptors appear to be present in thismuscle mediating different responses. In particular,kappa receptors seem to act as positive modulators ofcontractions activated via muscarinic receptors in thismuscle. (Supported by a COLCIENCIAS Fellowship toA G. and by NIH Grants MH48190 and GM08102)

DAILY VARIATION IN GAHA LEVELS IN THEBRAIN OF A COCKROACH, L1OIC0PIIAEA iMADERAK.B.R. F e r r e l l * , D.B. Dahl, j " . McCay,~K.Romero, J . Gibson, J . Newton. WesternKentucky U n i v e r s i t y .

Brains were s u r g i c a l l y removed a tt h r e e hour i n t e r v a l s throughout a 24 htime per iod from f l a sh Crozcn a d u l t malecockroaches t h a t had been accl imated to a12 h light/12 h dark cycle (light onsetat 0600h) at 25+2°C. An HPLC-fluoro-metric detection assay was used todetermine brain levels of the neurotrans-mittcr, gamma-aminobutyric acid (GABA),in six animals at each sampling time.Brain levels of GABA were significantlyhigher at midday than al l other timesexcept one during the 24 h time periodscanned.


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160 161HEXAMETHONIUM BLOCKS THE DEPOL-ARIZING EFFECT OF ACETYLCHOLINE INDISSOCIATED MUSCLE CELLS AND INSEMI-INTACT PREPARATIONS OF THEPTEROPOD MOLLUSC CLIONE LIMACINA.C.S. Courtney and R.A. Satterlie.Arizona State University, Tempe.

Intracellular recordings wereconducted in both acutelydissociated and cultered musclecells in conjunction with pressureejection of the putativetransmitter acetylcholine (ACh).Application of lO^M ACh resulted indepolarization of dissociatedmuscle cells. This depolarizationwas prevented when ACh was appliedin the presence of lCC'Mhexamethonium. In semi-intactpreparations, small motoneuron toslow-twitch muscle connections weresimilarly blocked by hexamethonium.Connections from general excitormotoneurons to both slow and fast-twitch muscle cells were notblocked in hexamethonium. Inaddition, startle motoneurons,which also innervate the swimmingmuscle continued to produce musclecontractions in the presence ofhexamethonium.

ZEBRA MUSSEL GILLS: LONG TERM CULTUREAND CONTRACTILE RESPONSESJ. Duncan*. J.L. Ram, P.P. Fong, and V. Snow,Department of Physiology. Wayne Suite Univ.. Detroit.Ml (intuxlucliun by Curt Swansoii).

Zebra mussels are an exolic nuisance species in NorthAmerican fresh waters. The study of zebra mussel gillsin vitro would be useful for determining responses totoxic agents and for understanding physiological regula-tion. One of the first tissues encountered by dissolvedenvironmental chemicals and control agents are the gills.The gills present a large surface area for capture of foodpanicles and exchange of dissolved gases. Movement ofparticles over the gill has been well-studied, but gill con-traction has been studied little, if at all, in bivalves,although such responses are known in other molluscs.The puipose of this study was to determine what neuro-transmitters caused contraction/relaxation of zebra mus-sel gill and to develop an in vitro system of culturinggills for studying cellular properties and methods of dis-rupting them. Freshly dissected gills contracted in re-sponse to acetylcholine (ACh), FMRFamide, dopamine,and high K + . Serotonin relaxed gills or increased theirrate of relaxation after ACh or K -elicited contraction.Gills weie viable in cultuic up to 13 days, as assessed bycontinued ciliary movement, occurrence of spontaneouscontractions, and contractile responses to neurotransmit-tcrs. Cultured gills died within two days of exposure tothe protein synthesis inhibitor anisomycin. Thus, me-thods for long term and toxicity studies of zebra musselgill function in vitro have been demonstrated, (funded bySea Grant and APS).

162 163

ION TRANSPORT AND ACID-BASE BALANCEIN FRESHWATER BIVALVES.R.A. Byrne and T.H. Dietz*. SUNY College atFredonia and Louisiana State University, BatonRouge.

Freshwater bivalves maintain ionic homeostasis bymeans of epithelial ion transport and this, in turn,may alter extracellular fluid (ECF) acid-base status.We examined Na and Cl transport characteristics,changes in ECF acid-base and ionic concentrations inCorbicula fluminea and Carunculina texasensis inpondwater, in Na or Cl free media, and when stimu-lated by exogenous serotonin. Carunculina controlsECF homeostasis by altering ECF Cl concentrations.Sodium transport was proportionately more affectedby serotonin than was Cl transport and acid-base dis-turbances ensued due to this disparity. In contrast,Corbicula had Na and Cl transport systems that, al-though largely independent of one another, were af-fected essentially equally by serotonin stimulation.ECF pH seems to be mostly under the control of res-piratory responses. The two species demonstrate sig-nificant differences in ECF homeostatic mechanismspossibly related to their disparate history in freshwa-ter. Supported by NSF 90-17461.

RED BLOOD CELL CIRCULATION AND OXYGENTRANSPORT IN HEMIPHOLIS ELONGATA (OPHIUROIDEA,ECHINODERMATA). A.M. Beardsley1 and J.M. Colacino.Clemson Univ., SC.

Unlike other burrowing ophiuroids Hemipholis does notventilate its burrow to bring oxygenated water to parts of thebody buried in reduced anoxic sediment. It must therefore relyon circulation of the water vascular system (WVS) fluid fromexposed arms to the buried body to transport oxygen.Hemipholis may augment this transport with hemoglobincontaining cells (RBCs) thai circulate with the fluid of the WVS.To study the circulation animals were established in laboratoryaquaria containing native sediment and high surface walerPO2 (>120mmHg). Typically the disc and 1-2 arms are buriedseveral cm below the surface, where the P02 of the burrowwater, is 23.7±B.3(sd) mmHg (n=42). Sediment lining theburrow is oxidized, both in the field and laboratory. Animalsextend the remaining arms, bearing numerous RBC-filled tubefeet, 2-4cm into the water column. Periodically, the tube feeton each exposed arm contract in a wave beginning at thedistal end of the arm and moving towards the disc. This actionforces RBCs into the radial canal and presumably into the disc,thus delivering oxygen to buried parts. Computations basedon estimates of WVS volume (1B.6±5.9(sd)mm3(n=5)), totalhemoglobin (8.5x10"5±4.7x 1O"5(sd)mmol (n=9)), volume olexposed contracting tube feet (65 pairs (n=8), 6.69x10'3±3.69xfO'3 (sd)mm3/tube foot (n= 43)), contraction rate of tube (eel(3±1(sd)/min (n= 8)), wet weight (0.3910.16(sd)g (n=9», andrespiration rate (0.1075 m!O2/(gh) (Heatwole, 1981),measured on animals exposed to air-equilibrated seav/ater)indicate that oxygen could be supplied to the buried tissues ata rate (0.123m!O2/(g-h)) sufficient to support aerobicmetabolism. Supported by Sigma Xi, Lerner-Gray Foundationand SIocum-Lunz Foundation to A Beardsley.

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CHANGES IN STRUCTURE AND FUNCTION UYACH1C1A MALPIGHIANTUBULES IN RESPONSE TOSECRETAGOGUESSpring, J II , MM. Felgenhauer', D W. Dulion ami C.I.Bordclon Univ. Southwestern Louisiana, Lafayclle.

The Malpighian tubules of the house cricket, Achcia.are composed of two morphologically and functionallydistinct regions, each comprised of a single cell typeFluid secretion by the mid-tubule (about 75% of the totaltubule length) was initially 150-200 pi mm"'.mm' andincreased 3-fold following treatment with cither cAMP ormethanohc extracts of the corpora cardiaca (CC). Thesodium-potassium ratio in stimulated mid-tubules was1:1, compared to 1:2 in controls. These changes in therale and composition of the secreted fluid wereaccompanied by marked changes in ullrastructurc,particularly in the morphometry of the basolaleral infoldsand the fine structure of the basal lamina Notablechanges were also seen in the morphology and position ofthe mitochondria, and there was a pronouncedmobilization of the splicriles, which are calciumphosphate gianules embedded in the cells lullacolkilarcalcium concentrations were followed in living cellsusing fluorescence ratio imaging Treatment of wholelubules with both CC and cAMP produced increases inthe concentrations ofmlracellular calcium, independentof the mobilization of the splicriles Supported by LEQSFgrant RD-A-41 to JHS and USDA grant 9301639 to JI ISandBEF

SELECTIVE BLOCKADE OF DISTINCTHEMOGLOBINS IN INTACT SYMBIONT-HARBORING GILLS OF Lucina peclinaia.B. K. Gaschen*, H. K. Smith and D. W. Kraus.Univ. of AL at Birmingham.

The symbiont-harboring gill of the clam Lucinapeciinata contains three distinct cytoplasmichemoglobins, isolated as hemoglobins I, II, and 111.The functional roles of these hemoglobins withinthe symbiosis has not yet been demonstrated invivo. All three hemoglobins have very similaroxygen affinities which are achieved with reactionrate constants that differ by more than 500 fold. Incontrast, the hemoglobins exhibit distinct carbonmonoxide affinities which differ by 4 to 80 fold.The ability to selectively bind the hemoglobins withcarbon monoxide was studied spectrophoto-metrically with intact gills in a thin layer cuvette.We followed the conversion of oxyhemoglobin tocarbon monoxide hemoglobin while adjusting theratio of carbon monoxide to oxygen partialpressures in the equilibrating gas. A titration curveof the magnitude of the carbon monoxidehemoglobin absorbance peak plotted against thecarbon monoxide to oxygen ratio was comprised ofat least two distinct plateaus, indicating selectivebinding of each hemoglobin with carbon monoxide.This technique provides a powerful tool with whichto investigate the role of each hemoglobin in asulfide-oxidizing symbiosis. Supported in part byNSF1BN9343430.

166 167Evidence for Elcctro.sen.silivily in Phniklivurous Feedingin (lie Psitldlcfisli Polyodon spatln/la.Lou A. Wilkcns, Mark Cox, and David Russell University ofMissoun-St. Louis

We present evidence llml clcclroscnsilivity is involved inplanklivorous feeding by Hie pnddlcfish, :l large filter-feedingrnm-vcnlilnliug fish. Several aspects of pnddlcfish biologypoint lo a role for clcctroscnsitivity in filler feeding, includingthe dnik, muddy-river environment, poorly developed eyes,and the enlarged roslruin richly endowed with nmpullnryrcccplors. The ampullae arc similar to the Lorcii/.ini.inampullae of clasmobranchs (Jorgcnscn, Flock and Wcrsall,1972) and clcctroscnsitivily has been established clcclro-physiologicnlly (New and Bod/jiick, 1985) and bchaviorally(unpublished results). Small paddlcfish (10-12 cm long) wereplaced in a rccirculaung artificial stream wiili a flow ralematching their vcnlilalory swimming speed. The water flowwas laminar, with gates restricting (lie fish (o a regionmonitored by IR-scnsilivc video cameras inoiinlcd below andfrom the side of the chamber. Live ndull brine shrimp wereintroduced, and feeding was video recorded in both thevertical and hori/.onlal planes. In single-frame analysis,distances were measured for brine shrimp passing above,below, or lo cither side of the rostrum in relation lo whetherthe) were ingested by the fish. Under fluorescent roomlighting, the paddlefish fed only on brine shrimp passingwithin 4-5 cm of the surface or the edge of the rostnim, wilhcaplurc frcqucnc> dropping o(T lincarlv with increasingdistance. Similar results were obuiincd from feedingexperiments conducted under infrared lighl (/. ~ 881) mil).Thisc results nrc consistent witli the Inpolhesis tlial llicrcj>;."«... ...:J .u .uiipi.II.in ^lj;lrjr-wCpti.r> uro *: cJ S the

paddlefish lo detect and feed on small plnnktonic prey

CHANGES IN BLOOD PARAMETERS INSTRESSED SHARKS DUE TO CAPTURE ANDRESTRAINT.E. Hull', C. Maniie'.R. Hueter* and R. Spieler''Nova Southeastern Univ., Dania, FL. ' MoteMarine Laboratory, Sarasota, FL.

Previous research has indicated speciesspecific stress responses in sharks. Wecompared serum parameters at five levels inthree species of sharks: bonnethead {Sphyrnatiburo) n=36; blacktip (Carcharhinus limbatus)n=33; and bull (C. leucas) n= 27. Stress level ofeach animal was judged using an index ofbehavioral response to capture and restraint,devised for use in tag-recapture studies, whichconsisted of five levels ranging from level 1"minimal stress response" to level 5 "dead1.Serum parameter levels were analyzed with acommon clinical profile. Hematocrits also weremeasured, but no differences among levels werefound in any of the three species. With increasedstress, S. tiburo showed increased potassium,inorganic phosphorus, total protein, and uric acidand decreased glucose (P<0.01). C.imbaius hadincreased uric acid and potassium (P<0.01),while C. leucas had increased potassium andinorganic phosphorus and decreased glucose(P<0.01). These changes in blood parametersmay help explain differences in species specificmortality rates due to stress.


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MITOCHONDRIAL SULFIDE OXIDATION INMUSSEL GILLS. R.W. Lee*, D. W. Kraus and J.E. Doeller, Univ. AL at Birmingham.

Hydrogen sulfide, a potent inhibitor of aerobicrespiration, is a common constituent of coastalmarine sediments, and organisms inhabiting high-sulfide muds may have mechanisms to garnercellular energy from sulfide oxidation. High sulfideis present in Spartina grass beds inhabited byCcukensia demissa. In excised gills from freshlycollected G. demissa, oxygen consumption,measured with closed-chamber respirometry, wasstimulated nearly 3-fold by 200-500 |iM sulfide andremained stimulated at I mM sulfide. In contrast,in excised gills from G. demissa maintained inaerated scawatcr for 1-2 months prior toexperimentation, oxygen consumption wasstimulated less than 2-fold by 200 (iM sulfide andwas inhibited by 0.5-1 mM sulfide. In excised gillsfrom Myiiliis galloprovincialis freshly collectedfrom off-shore platforms, oxygen consumption wasinhibited by 200 \iM sulfide. These results indicatethat sulfide stimulation of oxygen consumption maybe a function of sulfide exposure in theenvironment. Nearly 60% of G. demissa gillsulfide-stimulated oxygen consumption wasinhibited by the mitochondnal cytochrome oxiclaseinhibitor cyanide. These experiments and otherswith mitochondria! inhibitors indicate that amajority of sulfide-stimulated oxygen consumptionmay involve electron flux in the mitochondrialelectron transport chain. Supported in pan by NSFIBN9219658.

INTRACELLULAR pH OF SYMBIONT-HARBORING GILLS OF Solcmya reidi. O. W.Kraus* and J. E. Doeller, Univ. AL at Birmingham.

The clam Solcmya reidi contains sulfide-oxidizing bacterial symbionts and hemoglobin ingill cells. Both oxygen and sulfide arc necessaryfor symbiont chemoautotrophy.and sulfidedramatically alters the kinetics of hemoglobindeoxygenation in vivo. To determine if thisalteration is a result of sulfide-mediated changes inintracellular pH (pHi), gill cells in excised filamentswere loaded with the pH indicator 6-carboxyfluorescein, chosen because its absorbanccspectrum and that of hemoglobin show minimaloverlap. Standard curves were generated in high-potassium artificial seawatcr in the presence of.nigericin, a cation ionophore. In the absence ofsulfide, pHi was 7.4 at ambient pH (pHa) of 7.8.Gill pHi ranged from 7.0 to 7.5 as pHa changedfrom 6.5 to 8.2, indicating a moderate bufferingcapacity. Over the same pHa range, hemoglobinoxygen saturation in vivo, measured near 50%saturation (pO2 of around 7 lorr), increased slightlywith decreasing pHi. These results may indicatethat hemoglobin-oxygen affinity is responsive topHi cither directly via a reverse Bohr effect orindirectly via products of metabolic adjustments. Inthe presence of high sulfide levels (> I mM), pHidecreased only about 0.1, thus sulfide-mcdiatedchanges in pHi should have a minor effect onhemoglobin-oxygen affinity and the kinetics ofdeoxygenation. Supported in part by NSFIBN9343430.

170 171

EFFECTS OF l'EHKINSUS MAK1NUS ONADDUCTOR MUSCLE GLYCOGEN STORESIN THE OYSTER CKASSOSTMLA V1RGINICAL. E. Burnett* and S. Choi Univ. of Charleston,Grice Marine Laboratory, South Carolina.

We measured the amount of glycogenstored in the dark and the white adductor musclesof oysters infected with I'erkinsus nuinmi.s.Uninfected oysters had an average of 1311 mgglycogcn/100 g (±158 s.em.) dark adductormuscle and 902 mg/100 g (±\ 14 s e.m.) whiteadductor muscle. Oysters with light infectionshad significantly less glycogen in the darkadductor (82O±123 nig/100 g), but not the whileadductor (648±153 mg/100 g) Oyslcis withheavy infections had significantly less glycogen inboth dark (579A44 mg/100 g) and white adductormuscles. Glycogen levels in infected anduninfected oysters exposed to air for several daysdeclined significantly. This study suggests thatenergy reserves in oysters infected with /'.marinus may be seriously depleted and maycontribute to mortality, especially if the adductormuscles are unable to hold shells closed.(NA47FL0151 Oyster Disease ResearchProgram.)

CONTROL OF SWIMMING SPEED: AXIALKINEMATICS OF THE POLYCHAETE WORMNEREIS VIRENS.

S.S. Cavanagh* and J.H. Long, Jr. Vassar College,Poughkeepsie, NY.

Nereid polychaetes are unusual undulatoryswimmers — the waves of axial bending travel forward,from the tail lo the head. Forward motion isthought lo be possible because of thrust activelyproduced by the parapodia, which beat in the oppositedirection of wave propagation. Given (he importance ofparapodia, what ihcn is the role, if any, of the bodyaxis in controlling swimming speed? To address thisquestion we measured the kinematics of Nereis swimmingin a still-waicr tank; motions of their ventral surface werevideotaped at 60 Hz. Using multi-variatc regressionanalysis, we found that swimming speed increases with(1) increasing amplitude of the leading edge and (2)increasing propulsive wave speed. Whether these changesin axial motion produce thrust directly or enhanceparapodial ihnist production remains to be determined.In either case, swimming speed is controlled by acombination of axial and parapodial mechanisms.

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172 173EFFECTS OF BODY MASS AND DESICCATIONON THE LOCOMOTOR PERFORMANCE OF THETERRESTRIAUSOPOD. PORCELLIO LAEVISD. L. Claussen* and P. Loos Miami Univ.. Oxford.OH.

Terrestrial isopods are sub|ect to high rates ofevaporative water loss under a variety of naturalconditions. To investigate the consequences ofsuch loss, maximum sprint speeds of control andexperimental groups were measured over a 0.1 mracetrack segment The isopods were weighed,tested, and then placed in sealed containers oneither moist (control) or dry (experimental) papertowels for two to six hr All animals were thenreweighed and retested. Forty additional isopodswere kept in a dry container to find their criticalactivity and physiological death points. The deadanimals were then dried to a constant mass.Hydrated water contents averaged 71%, whereasessential water contents averaged 60 and 58% forcritical activity and physiological death pointsrespectively. None of these water contents weresignificantly dependent on initial body massRetesting did not significantly affect the speeds ofthe control animals. Speed increased with bodymass for all groups, with scaling exponents rang-ing from 0.33 to 0.96 Desiccation markedly andprogressively reduced locomotor performance,with speed extrapolating to zero at estimatedwater contents of 61 to 63%.

T U R N I N G B E H A V I O R O F R U N N I N GCOCKROACHES.D. Jindrich* and R. J. Full. University of California,Berkeley.

Previous studies of turning behavior in insects havefocused on the kinematics of walking around curves orescape turning behavior. We studied the behavior of thecockroach, Blabents discoidalis, as the animal turnedsharply while running. Since dynamic adjustments areessential to maintain stability, kinematic analysis alone isan insufficient descriptor of a complex and dynamicbehavior like turning. We videotaped cockroaches runningand turning on a photoelastic gelatin track to measure theground reaction forces generated by individual legs.Cockroaches were able to turn through a yaw angle inexcess of 20 degrees within one stride. Turns of varyingsharpness at speeds ranging from nearly stationary tomoderately fast running exhibited similar patterns of forceproduction. Force couples between the middle andcontralatcral hind legs rotated and accelerated the body inthe direction of the turn. Front legs contributed little toturning the body. The turning behavior of a rapidlyrunning, mancuverablc animal like the cockroach differsconsiderably from the behaviors observed in other insetsand the strategics employed by statically stable leggedrobots. ONR Grant N00014-92-J-1250.

174MANIPULATION BY THE CRAB CLAW REQUIRESCHORDOTONAL ORGAN INPUT. E.E. Johnson*P D. Storer, and H.B. Hartman. ShannonPoint Marine Center, Western WashingtonUniv , Anacortes. and Duquesne Univ.,Pittsburgh, PA.How dependent is the crab upon afferencefrom the propus-dactylus (PD) chordotonalorgan for voluntary control of the claw?We videotaped and quantified the manipu-lation of food by (\i_ncer_ in.i)1, isler wi Hiintact chclipeda. Next crabs were fedand videotaped after either a sham opera-tion, or the detachment of the distal endof the PD organ (dPD) from the dactyl ofthe claws. In contrast to the controlsand shams, statistical analysis revealedthat fine dactyl dependent manipulationof food (grasping, gripping, scraping,pulling and carrying) by dPD crabs signi-ficantly decreased. Manipulations notdactyl-dependent and which involved thechelipeds and walking legs (cradling,stabilizing, and guiding) significantlyincreased. Our results strongly supportthe hypothesis that PD organ afferenceis vital for the execution of fine mani-pulation directly involving the dactyl.Physiological recordings indicate thatthe neurons of dPD regain alive, positionci_ils f irlr.;; .:: ur.c'.i-racteri.stic high

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PARASITISM AND IIORMONliS ANDRKPROnUCTION IN HIROSNigella Ilillgatlh, Pepi. of/oologyand Burke Museum, University ofWashington, Seattle, WA 98195.

The results of experimentsdesigned to lest theimmunocompctence ol" testosteroneand other sex hormones in birds arcreviewed.A hypothesis is presentedsuggesting that corticosleronc maybe important in the direct andindirect regulation ol secondary sexcharacters. Corticoslerone is self-regulating, and immunosuppressiveat high levels, and may affectsecondary sex characters eitherdirectly through interference withthe production of a metabolite, orindirectly by lowering anotherhormone that is regulating thesecondary sex character.

PARASITOID EFFECTS ON IIOSTBEHAVIOUR: POSSIBLEPHYSIOLOGICAL MECIIANISMS.S. A. Ail.lino. Cornell Univcrsil). IthacaNY..

The tachinid lly Ormiu <n.hraceii l.iys livelarvae on its host the field cricket (e.g.Cryllu.s integer). Larvae initially developwithin a host's muscle, migrating into theabdomen on the 3rd clay. There theyconsume primarily fat body and muscle,but not female reproductive tissue. Whilethe larvae aie in the thoracic muscle, malesexhibit a slight increase in their tendencylo attack males. Male and femalecourtship remains normal until the daybcfoie larval emergence. However,oviposiiion is reduced 4 days earlier.Infestation by ihis tachinid also results inincreases in hcmolymph octopaminc levelsas well as in changes in some unidentifiedcompounds in the hcmolymph. Some ofthese changes correlate with the increasein male attacks on conspceifics or with thedecrease in oviposiiion that occurs duringinfestation. Unlike many hymcnoplcranparasiloids, O. oclimccti docs not appearlo induce changes in its host via polyDNA

197 198

HORMONAL CONTROL OF SECONDARYSEX CHARACTERS IN VERTEBRATES.Michael C Moore* and Diana K. HewsArizona State University, Tcmpc.AZ

Several recent models piopose that effects olparasites on secondary sex characters aremediated by parasite effects on hormone levels.These models oiler, assume very deterministicrelationships between hoimone levels andexpression of secondary sex characters orassume that these relationships are highlyconserved cvolutionarily. In contrast lo theseassumptions, we will use our results from twomodel systems to illustrate thai I) hormonalcontrol of secondary sex characters is complexand multifacetcd and 2) hormonal mechanismsarc evolutional ily labile. Our work on themountain spiny lizard illustrates how the action.1-of hormones can vary with season. Our woikon alternative male reproductive morphs in treelizards illustrates how selection can alter thefunction of a hormone and how differentcharacters in the same individual can becontrolled by divergent mechanisms. We hopethis information will assist nonendocrinologisLsin construction of hormonal models.

PARASITOID INFLUENCES ON HOSTREPRODUCTIVE SYSTEMS IN INSECTS.D.A. REED AND J.J. BROWNWashington State Univ., Pullman.

Natural selection has favoredparasitoids capable of castrating theirhost. The immediate reward could be toincrease host nutrients for parasitoidprogeny, but new evidence suggestscastration eliminates host gonads thatcan confuse the two-way endocrinecommunication between host andparasitoid. Ecdysteroids produced byboth the host and parasitoid serve tocommunicate physiological changesgoing on in both organisms. Insectshave become resistant to mostchemicals that man has devised fortheir control. The long term reward forbeing able to castrate one's host may beto assure that even the 'lucky' mutanthost capable of withstanding theparasitoids attack will not be able topass those genes on to subsequentgenerations.

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200 201PARASITIC EFFECTS ON HOST HORMONESAND BEHAVIOR.B.L. Hart. University of California, Davis.

This paper vvill introduce the array ofbehavioral defenses thai have evolved in vertebratehosts to enable them to avoid, reduce or destroyfitness-compromising parasites. There arc anumber of ways in which host hormones may alterthe pattern of behavioral defenses. For example,grooming in antelope, which is very effective in• cmoving ticks, may be down-regulated bytestosterone in territorial males allowing them toattend to herding females but at a cosl of increasedtick load. There is evidence that grooming isregulated by an internal clock, which like otherbiological clocks may be modulated by theendocrine system.

Parasites have sometimes evolved ways ofpenetrating or evading host defenses by cuing offofhosthormor.es. Legendary in this respect is themigration of the rabbit flea to relative safety fromgrooming adults by moving to helpless rabbit pupswhich are not even groomed hy their mothers. Thereproductive maturation and migration of sexuallyactive fleas from docs to newborn pups areintricately timed and regulated by hormonalchanges in the pregnant doc to take optimaladvantage of the pups for maximum feeding andreproduction by the flea.

PARASITES, FLUCTUATING ASYMMETRY ANDSEXUAL SELECTION.M. Polak ( In t roduced b y . . . ) . ArizonaS t a t e Univ . , Tempe and Centei forInsec t s c i e n c e , Tucson.

Degree of f l u c t u a t i n g asymmetry inbilateral traits reflects individual abi-lity to buffer developmental processesfrom stress. Recent data on a limitednumber of species are reviewed whichindicate that differences in asymmetryinfluence sexual selection and that para-sitism and asymmetry are positively as-sociated, either because asymmetricindividuals are more susceptible orbecause parasitism causes increasedasymmetry. Causes of asymmetry may begenetic or non-genetic in nature, but alargely overlooked mechanism could ope-rate through maternal effects. I testedwhether parasitism and age in mothersinteract to effect fluctuating in maleoffspring. If genetic differences amongmothers influence probability of infest-ation, maternally-induced differences inasymmetry among sons may reflectheritable ability to avoi-d or combatinfection. The DuPont Co. is acknowledg-ed for support.

203 204

HOST BEHAVIOR MODIFICATION BY PARASITES:AN EVOLUTIONARY PERSPECTIVEKuris, A. M. University of California, Santa BarbaraBehavioral modification of hosts by parasites is a type

of pathology that either increases the fitness of theresident parasites or is a side effect of other factorsthat increase their fitness. It is sometimes difficult toseparate these effects from host defensive behaviors.These issues are compared across parasitoid,parasitic castrator, typical parasite, and micropredatorlife histories. Important factors influencing hostbehavioral modifications are relative sizes (energetics)and relative longevity of host and parasite, therelationship between intensity and pathology and theextent to which the combined host plus parasitephenotype is controlled by the respective genotypes ofthe host or its parasites. Parasitoids and castratorshave the greatest potential to control the behavior ofthe combined phenotype. They reach large sizes andoften have the physiological machinery to governcomplex host behaviors.

ECOLOGICAL IMPACTS OF HOST MODIFICATIONSLafferty, K. D University of California, Santa Barbara.The trematode parasite Euhaplorchis cahforniensis

completes its life-cycle in salt marsh snails, fish andbirds. This trematode serves to illustrate howparasites affect the ecology of their hosts. Trematodescastrate their first intermediate host snails This canlead to reductions in snail densities Snails attempt toassure reproduction by maturing at smaller sizes inareas where the risk of castration is high The strategyof the trematode in the fish is quite different from itsstrategy in the snail Here, transmission occurs wheninfected fish are eaten by a bird Anything that thetrematode can do to facilitate this will increase itsexpected fitness. Infected fish appear moreconspicuous; they make abrupt surfaces, jerksuddenly, vibrate, bend at right angles, and scratchthemselves on the bottom. These behaviors may beimposed by the parasite in order to facilitatetransmission to piscivorous birds Increased mortalitymay reduce fish density. Birds are intelligent foragersand presumably recognize when a fish is behavingabnormally. Given this, should a bird avoid parasitizedfish? In doing so, it would benefit from reducedparasitism but would suffer the cost of reduced foodintake. Mathematical models suggest that birds shouldrarely avoid parasitized prey and may, under somecircumstances, benefit from the presence of thetrematode in the salt marsh. Trematodes link severalspecies in the salt marsh food web. Their piesenceindicates a healthy, functioning ecosystem.

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205 206ALTERATIONS OF SEXUAL MORPHOLOGYAND SEXUAL BEHAViOR IN MERMITHID-INFECTED MAYFLIES.S. A. Vance. Cornell Univ., Ithaca.

This study investigated the impact of infectionby a mermithid nematode on the secondarysexual morphology and behavior of the mayfly,Baetis bicaudatus. Infertility in uninfected adultswas rare (<0.5%), however all parasitized indiv-iduals showed complete castration (100%).Based on external morphology, the sex ratio ofunparasitized mayflies was54% female, 46%male (n=483). For parasitized individuals the sexratio was 70% "female" appearance, 30% inter-sex and no "males" (n= 84). Neither differentialmortality nor differential infection of the sexesappear to explain this pattern. Parasitizedmayflies did not participate in male swarms. Both"females" and intersexes were observed withgravid unparasitized females conductingupstream migrations and ovipositing behaviors.These observations combined with geneticanalysis (karyotyping, flow cytometry) suggestthat mermithid infection feminizes the sexualmorphology and sexual behavior of the malemayfly. Feminization of male host behaviorwould be advantageous for the parasite for tworeasons. 1) It ensures that the parasite willcomplete its life cycle, and 2) it enhancesparasite dispersal. Male sexual behavior wouldnot achieve these ends as males swarm overland.

PARASITISM-INDUCED ALTERATIONS I NHOST GROWTH AND METABOLISM IN THETOBACCO HORNWORM. MANDUCA SEXTA.M. van Laarhoven*, M.A. Chappell, and N.E.Beckage. University of California-Riverside.

Parasitism by the braconid wasp Cotesiacongreoata causes major changes in food consumptionand growth of the host, Manduca sexla. Parasitizedlarvae rarely attain weights in excess of 8 g, whereasunparasitized larvae weigh 8-10 g when metamorphosisensues. Nevertheless, despite the overall inhibitoryeffect of parasitism on host growth, we observed thatfollowing parasrtization of fourth instar larvae, the wet anddry weights of more heavily parasitized individualsexceeded those with smaller parasite loads, suggestiveof a parasitoid density-dependent mechanism of hostgrowth regulation.

To compare the metabolic rate of parasitized andunparasitized larvae, the resting VCO2 w a s measuredusing flow-through respirometry. Hosts were parasitizedas newly ecdysed fourth instars and monitored untilwasps emerged 12 days later. Unparasitized larvae weremonitored until the wandering stage. The weights andmetabolic rates of parasitized individuals increased at aslower rate compared to unparasitized controls. At 7days post-oviposition, a sharp one day drop in metabolicrate occurred, which appeared synchronized with thefirst larval molt of the parasitoids Two days before waspemergence the host stopped feeding and exhibiteddramatically reduced levels of spontaneous locomotion.Simultaneously, the host.s metabolic rate dropped, andrespiration became periodic. Financial support wasprovided by NSF IBN-906003-04 to N.E B. and theUniversity of California-Riverside

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TEMPORAL PA1TERN OF HOST IMMUNO-SUPI'RESSIONIN MANDUCA SEXrA LARVAE PARAS nTZED BYCOTESIA CONCREGATA.M.D. Lavinc* and N.E. Bcckagc. University of Califomia-Rivcrsidc. Riverside, CA 92521-0314

Parasitism by Ihc braconid wasp Cotesia congregalasuppresses Ihc cellular immune responses of host tobaccohornworms. To assay effects on encapsulation, Scphadcxbeads were injected into Af. scxta at different limcpointsfollowing parasilizauon. Positively charged Scphadcx A-25 beads were encapsulated and mclani/.cd at a significantlylower rate in larvae parasitized 24 hours earlier, compared tounparasili7.cd controls. However, larvae parasitized 8 daysearlier showed encapsulation and mclanizalion rates notsignificantly different from controls. Negatively chargedC-25 beads were not encapsulated or mclani/cd inparasitized or control larvae Encapsulation of A-25 beadsalso was inhibited in non-parasilucd larvae that wereinjected with the wasps' polydnavirus virions, suggestingan initial virally mediated shutdown of the host'sencapsulation response likely occurs. Encapsulation ofparasite eggs injected without calyx fluid indicates that thisimmunosupprcssion is necessary for parasite development.However, by 8 days post-wasp oviposilion, theencapsulation capability of the host has recovered, so thedeveloping wasps must be using an alternative strategy toescape encapsulation. The poor encapsulation response byM. sexla to negatively charged beads suggests that thesurface charge of the wasp's eggs and larvae may play a rolein thcu avoidance of encapsulation. The observed patternof immunosupprcssion also correlates with othertemporally variable aspects of parasitism, such asmorphological alterations in the host's hemocytes andlevels of expression of virally encoded proteins. Supportedby NSFirtN-906003-04 to N.E.B.

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226 227METABOLICALLY-INDUCED CHANGES IN INSULIN-LIKE GROWTH FACTOR-BINDING PROTEINS (IGF-BPs): CONSERVATION AMONG VERTEBRATES?K.M. Kelley*, K. Siharath, C.S. Nicoll,R.G. Rosenfeld and H.A. Bern.Oregon Health Sciences Univ., Portland,and Univ. of California, Berkeley

IGFBPa exist in vertebrates asimportant regulators of IGF action andare strongly affected by metabolic cuesand hormones. In uncontrolled type-Idiabetes raellitus, circulating levels ofIGFBP3 in rats, and a similar protein inthe goby (Gillichthys mirabilis), arereduced, while levels of IGFBP1 in rats,and a similar protein in the goby, areincreased; insulin therapy restores IGFBPlevels to normal in both. Similar changesin the circulating levels of these IGFBPsoccur with fasting and refeeding. Theimportance of IGFBPs in regulating localIGF action)s) may be observed in thediabetic kidney of mammals which showsabnormal growth leading to nephropathy.Despite reduced kidney IGF-I mRNA levelsand low serum IGF-I, diabetic rat kidneyshows high IGF-I peptide concentrations.Changes in gene expression of all sixIGFBPs in the diabetic rat kidney will bedescribed, in an attempt to implicate oneor more IGFBPs in maintaining the highlocal IGF-I peptide levels. Possibleparallels in local/tissue-specific IGFBProle(s) in fish will also be discussed,as differential tissue production ofIGFBPs occurs in striped bass (Moronesaxatilis)• (Aided by CA Sea Grant, HIHgrant 0HD14661, and Zenyaku Kogyo Co.).

GROWTH-PROMOTING ACTIVITYOF PROINSULIN IN FISH.E.C. Urbinati*, M.D.Willis andE.M. Plisetskaya. UNESP, Jaboticabal,Brazil, and Univ. of Washington, Seattle.

Insulin precursor, proinsulin, isstructurally homologous to the insulin-likegrowth factor-1 (IGF-1). Being almostdeprived of metabolic potency, pro-insulinpossessed some growth-promoting activitywhen tested on cultured human fibroblasts(King and Kahn, 1981). We evaluatedincorporation of 35s-sulfate into sites ofskeletal growth in gill arches from trout{Oncorhynchus mykiss) and sockeye salmon(0. nerka) and effects of mammalian pro-insulin, insulin and IGF-1 on sulfate uptake.Isolated cartilages were incubated for 48hours in the presence of 1nCi 35s-sulfateand either 10-1000 ng of peptide or thevehicle. Growth-promoting activity ofproinsulin varied depending on fish speciesand/or the season of experiment. In trout inMarch-April, 10 ng/well of proinsulin causedsignificant increase in sulfate incorporation,while a dose of 500 ng/well was required fora comparable effect in sockeye salmon inJuly. Supported by grants NSF #DCB-89115935to E.M.P. and CNPq, Brazil, to E.C.U.

228 229ONTOGENIC PATTERNS OF CIRCULATINGCONCENTRATIONS OF GROWTH HORMONEAND INSULIN-LIKE GROWTH FACTOR-I INTHE JAPANESE QUAIL AND STARLING*W.A. Schew and C.G. Scanes, Univ.Pennsylvania, Philadelphia, RutgersUniv., New Brunswick.

The ontogenic patterns ofcirculating concentrations (cone.)of growth hormone (GH) and insulin-like growth factor-I (IGF-I) wereexamined in precocial (slowgrowing) quail and altricial (rapidgrowing) starlings. Plasma GHcone, were high in young chicks ofeither species and declined priorto the attainment of adult bodyweight. Plasma IGF-I cone,increased in chicks with age posthatch but then declined prior tothe termination of body growth.Feed restriction reduced the plasmacone, of IGF-I and increased thoseof GH. These patterns wereobserved for both species althoughthe ontogenic profiles weretemporarily shifted to the left inthe starlings. It is suggestedthat stage of growth netchronological age is r.ore importantfor t.-.e or.tcge.-.ic patterns of GHand IGF-I.

ELEVATION OF SOMATOLACTIN IN REDDRUM PLASMA FOLLOWING TRANSFERTO A DARK BACKGROUND TANKY. Zhu* and P. Thomas. Marine ScienceInstitute, University of Texas, Port Aransas, Tx

Somatolactin is a novel hormone identified inthe intermediate lobe of teleost pituitaries which isstructurally related to growth hormone andprolactin. Somatolactin (SL) was purified frcmred drum pituitaries and a specific RIA with adetection limit of 0.14 ng/ml.was developed forits measurement in red drum plasma. Juvenile reddrum acclimated to light background tanks a. thebeginning of the experiment had mean plasma SLlevels of 0.5 ng/ml. Plasma SL levels rose in reddrum within three hours of transfer to darkbackground tanks, they were significantly elevated(3.2±0.86 ng/ml) one week after transfer, andwere maintained at high levels for one month.Plasma SL levels were low and did not changesignificantly over a 2-month period in respor.se toexposure to low salinity seawater and fresh water.However, a significant decrease in circulating SLlevels was observed 20 minutes after exposu-e toa shallow water and netting stressor. Thesepreliminary results suggest that SL may havt arole in adaptation to dark backgrounds in rcr!drum.

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230 231OSMOREGULATORY PROGRESSION INSTUNTING COHO SALMON AND EFFECTSOF GROWTH HORMONE INJECTIONS ONFRESH WATER-ADAPTED AND SHORT-TERM SALTWATER-REINTRODUCEDSTUNTSA.S. Schreiber" and R.J. White EasternWashington Univ., Cheney WA.Stunted coho salmon have been shown to be

hypo-endocrine, with the exception of growthhormone which exists at levels four to five timesthat of normal smolts. Coho salmon yearlingstransferred to saltwater (SW) for 5 months firsthypoosmoregulated more effeciively than smolts(blood plasma osmotic pressures [o p.] 309.8+7vs. 337.7±8 mOsms, higher gill Na+<K+-ATPase[ATPase] and posterior intestinal water uptake[Jv)), but 5 days later exhibited osmoregulatoryfailure (plasma o p. 404.2±11 mOsms, higherintracellular liver K+ concentrations, lower gillATPase and Jv). Freshwaterreacclimated stunts(1 mo ) introduced to 67% SW (12 hrs.) hadlower plasma o.p than smolts (360.4±0.4 vs.380±0.8 mOsms). Growth hormone (GH)injections raised stunt gill ATPase afterfreshwater acclimation. Following 67% SWintroduction GH injections elevated stunt gillATPase and reduced o.p. compared to placebos(328.7±3.9 vs. 360.4±0.4 mOsms) AdvancedSW stunt intracellular liver K+ concentrationscorrelated positively with plasma o p , whereasmuscle K+ did not. Increased liver K+ due tostress may contribute to osmoregulatory failure.

OSMOREGULATORY ACTIONS OFGROWTH HORMONE IN AN ADVANCEDTELEOST.Sakamoto, T.1, B.S. Shepherd1, R.S. Nishioka2,S.S.Madsen2, J. Siharath2, N.H. Richman HI1,T.T. Chen3, H.A. Bern2 and E.G. Grau1*.1. University of Hawaii, Honolulu, 2. Universityof California, Berkeley and 3. University ofMaryland, Baltimore.

To date, growth hormone (GH) has beenshown to contribute to seawater adaptation onlyin salmonid fishes. We examined the role ofGH in the osmoregulation of an advancedeuryhaline cichlid teleost, the tilapia,Oreochromis mossambicus. Transfer of tilapia toSW resulted in a rise in plasma level of GHfollowed by an increase in mRNA for insulin-growth factor I (IGF-I) in gills and liver. Bycontrast, neither plasma GH nor IGF-I mRNAchange after transfer from seawater to freshwater. Injections of tilapia GH suppressed theincrease in plasma osmolality which normallyfollows the transfer of hypophysectomized fishto seawater. It would appear that GH/IGF-Imay operate in the seawater adaptation of bothprimative and derived euryhaline teleosts.Supported by JSPS fellowship to T.S. and byNSF Grant DCB 91-04494 and NOAA/SeaGrant No. NA36RG0507/R/AQ-37 to E.G.G.

232 233

ENZYME IMMUNOASSAYS: ADVANTAGESAND PITFALLSG.F. Paciotti* and L. Tamarkin (Introduction byBarbara Gower). Cytlmmune Sciences Inc.,College Park, MD 20742

Detection of hormones in biological fluidshas historically been accomplished by RIAs,which are polyclonal antibody-based competi-tive binding assay systems. Non-radioactivecompetitive binding enzyme immunoassayshave been developed by conjugating analytesto biotin, creating a stable non-radioactive li-gand that may be detected with streptavidinconjugated to alkaline phosphatase orhorseraddish peroxidase. By immobilizing theantibody in wells of microtiter plates the sensi-tivity of these ElAs is comparable to RIAs,while the detectability of some hormones isactually enhanced. For example, this assaysystem measures cytokines in serum orplasma samples when these molecules areundetectable by two-site ELISAs. Recent useof color amplification systems yields increasedcolor per unit of analyte, which decreases%CV and increases precision. Where two-siteELISAs are ofttimes precise, but not accuratebecause of interference by blood borne bind-ing proteins, the competitive binding EIA isboth accurate and precise.

NON-RADIOACTIVE BIOLUMINESCENTIMMUNOASSAYS FOR ENDOCRINEHORMONES BASED ON THE Ca++-ACTIVATED PI 1OTOPROTEIN AEQUORIN.D. F. Smith , SeaLite Sciences, Inc., Bogart,GA 30622, introduction by B. Gower,University of Delaware, Newark,

The rccombinant form of a photoproteinfrom the jellyfish Aequorca victoria has beendeveloped as a non-radioactive tracer in animmunomclric, bioluininescent iinmunoassay(B1A) for the quantitative determination ofhuman TSH, FSH, LH and hCG, and in acompetitive formal iinmunoassay for thedetection of testosterone. Aequorin(AquaLitc®) is a protein complex thatconsists of a bound lucifcriri molecule and O2( total MW 22,000) that produces light (Xmax= 469 nm) upon addition of Ca++.Commercial luminoincicrs can detectAquaLite at the aiiomol level. The AquaLiteTSH assay detects aitomol levels of humanTSH (sensitiviiy = 0.001 mlU/L) in antibodycoated 12 x 75 mm lubes. A microtilerplatcbased TSH assay using a biotinylatcdconjugate antibody and AquaLitc®-streptavidin was sensitive to 0.007 mlU/Lusing a microtiier plate luminomcter.

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USE OF NJDDK RIA REAGENTS FORENZYME 1MMUNOASSAY.B.A. Gowcr*, T.R. Nagy, T.L Whclan, and M.H.Stetson. Univ. of Delaware, Newark.

We have used radioimmunoassay (RIA)reagents obtained from the National Institute ofDiabetes and Digestive Diseases and Kidney(NIDDK) for developing non-radioactive enzymeimmunoassays (EIA). Purified antigen, intendedfor iodination, was labelled wilh biotin. Antiscrawere diluted according to insliuelUm.s andirnmunoglobulins adhered lo 96-wcll plates via a"coating antibody" directed against the constantregion of the IgG of the species in whicli theprimary antiscra were developed. Referencepreparation was diluted according to directionsand applied to the plate prior to addition ofbiotinylated antigen. This protocol results in acompetition-based assay similar in theory to anRIA. Methods will be explained and data for ratprolaclin, hamster prolaetin, rat growth hormone,and ovine growth hormone assays will be shown.Application of EIA to measurement of scrumand pituitary hormone concentrations of collaredlemmings {Dicrostonyx grocnlanJicus) and ricerats {Oryzomys pahislris) will be discussed.Supported by NSF DCB87-14638.

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Comparative Physiology and Biochemistry

235 236

LOCOMOTOR MECHANICS OF THECENTIPEDE SCOLOPENDRA HEROS.BX). Anderson* and R J. Full. Univ. of California,Berkeley.

When undulating centipedes locomote theirlegs touch the ground only on the concave side ofthe bent body. As speed increases the number oflegs in contact with the ground decreases as theflexion of the body increases. We measured theground reaction forces at these individual points ofcontact, or foci, using a miniature force platform andby running the centipedes across a photoelasticgelatin while simultaneously videotaping the trial forlater kinematic analysis. The horizontal and lateralforces where ' / ; to V3 the magnitude of the verticalforce. The vertical force was greatest for legs in themid-portion of the body. The lateral force wasalways directed out from the body. The angle theleg makes with respect to the direction oflocomotion when in contact with the grounddetermines the direction of the horizontal or fore-aftforce. Legs primarily directed toward the anteriorend of the bogy tended to decelerate the animalwhile legs directed posteriorly accelerated it. Thehorizonal force generated by the more anterior legs(legs 3-9) tended to decelerate the animal while thatgenerated by the posterior legs (legs 15-20) tendedto accelerate the animal. Legs in the middle regionof the boy (legs 10-14) had average horizonal forcesthat neither accelerated or decelerated the body.When summed, single foci force patterns producedpatterns similar to whole body force recordings.

MECHANICAL ENERGY OF SWINGING SIX LEGS.R.J. Full*, R. Kram and B. Wong.Univ. of California, Berkeley.

Roboticists have predicted that less mechanical energyis needed to swing a greater number of small legs, whereassome functional morphologists have suggested the opposite.We videotaped cockroaches, Blabcrus discoidalis, at 1000f/sec from below through a transparent treadmill duringconstant-speed running (20 cm/scc). From 3D kinematicand morphological data, we calculated the mechanicalenergy required to move the limbs relative to the center ofmass. The mechanical energy generated for moving thelimbs (15mJ/stride or 37m\V/kg) was only 1/3-1/5 themechanical energy generated to lift and accelerate thecenter of mass. Mass-specific mechanical energy generatedby the trotting hexapod to swing its limbs was notsignificantlydifferent from two-legged runners and hoppersand four-legged trotters moving at the same absolutespeed. Cockroaches operate at relatively high stridefrequencies, but the relatively small leg mass and inertiaallows for rapid locomotion without exceptionally high limbenergy generation. ONR Grant NOOOI4-92-J-I250.

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NEAR-PERFECT ELASTIC STORAGE INTHE FLIGHT MOTOR OF DROSOPH1LA.M.H. Dickinson* and J. Lighton. Univ. ofChicago, Chicago., and Univ. of Utah,Salt Lake City.

A comparison of mechanical powermeasurements based on gas exchange andsimultaneously measured flightkinematics indicate near-perfect elasticstorage in the flight muscles and thoraxof Drosophila. Uni-'directional C02respirometry was performed on tetheredflies within a closed-loop visual flightsimulator, while simultaneouslymeasuring wing beat frequency, wingstroke amplitude, and yaw torque. For arange of possible muscle efficiencies, thevalue of elastic storage that provided theclosest fit between the respirometric andkinematic estimates of mechanical powerwas determined. Predicted muscleefficiences as high as 10% required elasticstorage approaching 90%, demonstratingextraordinarily efficient energy recoverywithin the flight motor of these smallflies.

A DIRECT MEASURE OF THRUST IN ANUNDULATING FISH MODEL.N.C. Boetticher* and J.H. Long, Jr. Vassar College,Poughkeepsie, New York.

Thrust and power for undulating fishes is usuallymeasured using hydrodynamic calculations. To empiricallytest the elongated-body theory, which is commonly used instudies of fish swimming, we directly measured the thrustand power required to swim a vinyl model of a scup(Stenolomus chrysops). The model was propelled bytraveling axial waves of bending that were generated by asinusoidal bending couple located cranially. By varyingamplitude and frequency of the input signal, we swam themodel steadily over a range of speeds (0.37 to 0.79 bodylengths/s). Thrust was measured by colliding the modelwith a force plate and determining, in an independent setof experiments, the relationship between the impact (N s)and thrust in a rigid (not undulating) model. Thrust andpower measured via elongated-body theory. We also foundthat thrust and power required for motion of the modelwhen undulating were greater than those required for themodel when rigid.

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239 240EFFECTS OF INCUBATION TEMPERATUREON BOX TURTLES HATCHLINGS: SIZE,GROWTH AND COST OF DEVELOPMENT.R. St. Clair, Univ. of Oklahoma, Norman.

Developmental environment may affectsurvival and fecundity by modifying offspring size,condition, and growth. With environmental sexdetermination, these effects may necessarily causesexual asymmetries in life histories. I incubatedeggs of two species of box turtle at 25 C (males)and 30 C (females) using standard Packardianprotocol. Hatchling wet mass was larger in males.Total oxygen consumption was compared by fittinga logistic regression model and integrating overdevelopmental time. When corrected for wet massof hatchling, males cost more than females (1.120kJ/g vs. 1.048 kJ/g), probably because females havemore residual yolk and are therefore less completelydeveloped. However, subsequent growth undersimilar conditions did not differ. Metabolic rate (at20 C, 25 C, and 30 C) of 8-month old hatchlingsincreased linearly with temperature in females butdecreased at 30 C in males. The differencesbetween males and females are provocative withinthe context of adaptive significance ofenvironmental sex determination but not fit wellwith the Charnov-Bull model.

DOES UPHILL RUNNING REQUIREHIGH MUSCLE FORCES?T. J. Roberts, R. A. Belliveau Jr., and C. R.Taylor. Harvard University, Cambridge, MA.

Running uphill is energetically expensive,dogs use twice as much energy to run up a 12degree incline as they use on the level. Wehypothesized that this higher cost might beexplained by increased muscle forces required togenerate greater muscle power outputs. To testthis hypothesis, we compared the amount ofmuscle force necessary to support the bodyduring level and uphill running in dogs andhumans. We measured muscle mechanicaladvantage and calculated muscle force in limbextensors (using high speed video and forceplate analysis at 0, 6, and 12 degree inclines).Mechanical advantage and average muscle forceof the limb extensors during uphill running werecomparable with level running values. Thisindicates that the high metabolic and mechanicalpower outputs of uphill running are the result ofincreased muscle shortening rather thanincreased muscle force. Supported by NIHgrant ROIAR18140 and an NSF GraduateFellowship to T. J. Roberts

241 242REPEATABILITY OF AEROBIC PERFORMANCEIN FREE-LIVING BELDING'S GROUNDSQUIRRELS.M.A. Chappell and G.C. Bachman. Univ.California, Riverside and Univ. California, LosAngeles.

We measured the repeatability ofmaximal oxygen consumption (VO2max) i n a

wild population of Belding's ground squirrels(Spermophilus beldingi) in eastern California.VO2max w a s ^'•cited by intense exercise andby acute cold exposure. Animals wereindividually marked, and repeatability ofVO2max w a s assessed over intervals of 2 h,6-18 d, and 1-2 years. We determinedrepeatability from correlation coefficients ofinitial and final mass-corrected residuals.Both thermogenic and exercise VO2max werehighly repeatable over 2 h intervals (r=.73and .88). Repeatability declined butremained significant over 6-18 day intervals(r=.38 and .4). VO2max was not repeatablebetween the juvenile year and the first yearof adulthood. However, significant between-year repeatability of exercise V02max w a s

found for aduits (although tne sampie sizewas small).

IMPACT FORCES DURING PLUNGEDIVING IN BROWN PELICANS.M.L. Blum* and S. Vogcl. Duke Univcisily.

I'lunge diving is an e\lirnic louring IH:II.IVIOIuscil by J iiumbci of avian species in whichindividuals fall head-first Irom u considerableheight into Ihc water in search of food.Although forces generated upon impact arclarge and cause rapid deceleration, plungedivers seem raiciy to suffer any adversephysical effects. Tliciclorc, the mechanicaldesign of plunge diving birds should beimportant in accommodating the I'oicc impulseThis study examines the compression forcegenerated by plunge diving at the hcjd/ncckjoint in the brown pelican, Pcleranusoccidenlalh. Forces ucrc calculated fromaccclcromctcr data and obtained using anexperimental system in which heads slide downwires into a water rcscnoir. These icsulLs aiccompared to other Foicc estimates ol blownpelican plunge diving.


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SIMULTANEOUS DETERMINATION OFMETABOLIC POWER INPUT, ACOUSTICPOWER OUTPUT, AND EFFICIENCY OFSOUND PRODUCTION IN A MOLECRICKET.

K.N. Prestwich" and T.J. Walker.Holy Cross Col., Worcester, MA andUniv. of Florida, Gainesville.

All previous studies of the efficiency of soundproduction in animals have involved non-simultaneous determination of metabolic andacoustic power because of the conflicting technicalrequirements of small volume metabolic chambersvs. the need to determine sound fields at least onewavelength away from the source Scapteriscusborelln , like other mole crickets, sings from within anacoustic burrow that should increase ihe cllicioncyof sound production We werq able to use theburrow as a gas sampling mask by drilling a samplingtube into it and then drawing air from the burrowopening across the calling cricket This allowed us todetermine V02. VCO2. a n d acoustic powersimultaneously. For 58 observations on 8 animals(mass = 0.816 ± SEM 0.062g) at 24° C, V02 = 2815± 337 nlO2/(gh), VCO2 = 2212 ± 313 ulCO2/(gh),RQ = 0 80 ± 0 02, net metabolic power input -= 12.50± 0 63 mW (ca. 6X resting), and acoustic power -21.6 ± 2 uW. The efficiency of sound production was0.18 ± 0.02%; this value is similar to those of cricketsthat do not use acoustic burrows.

ENERGY ALLOCATION STRATEGIES OKTHE ZEBRA ML'SSEL UNDER DIFFERINGENV1RONMENTAL CONDITIONSA. M. Stoeckmann* and D. \V. Garton. OhioState Univ., Columbus, and Indiana Univ..Kokomo.

Zebra mussel metabolic rates are sensitive toenvironmental conditions thus changing the energjavailable for growth or reproduction. Wemaintained mussels (n = 250) for seven weeks at12. 18, 24, and 30"C and fed three rations (2.5. 5,and 20% uf dry body miss day'1) of either a lowor high c|ii.ilily algal diet. We measured oxygenconsumption, ammonia excretion, shell and tissuegrowth, and gamete production, and calculatedreproductive effort (RE). Diet quality determinesallocation .strategy. In the high quality diet, REwas lower because growth was greater. In the lowquality diet. RE was higher because growth wasreduced. Mortality also increased in the lowquality diet because of reduced growth. Divertingenergy from somatic maintenance to reproductionwhen diet quality is low, increases susceptibility to1idilit10n.1l enviiomnentai siressors Zebia musselsalter eneigy allocation strategy in response toenvironmental conditions devoting a greaterproportion of energy to reproduction underStressful conditions.Project funded by the National Sea Grant program.

245 246

DO OYSTERS FEED DURING SETTLEMENT

AND METAMORPHOSIS?

S M. Baker" and R. Mann Virginia

Institute of Marine Science, College of

William and Mary, Gloucester Point.

The feeding ability of oyster

(Crassostrea virginica) larvae during

settlement and metamorphosis was

observed using flourescent

microspheres. Feeding with the larval

velum occurred during the searching

and crawling stages of-settlement, but

not during cementation. In newly

settled larvae, 16% engaged in feeding

using the velum while 84% did not

feed. All later metamorphic phases

fed, although the mode of particle

capture was unclear. Mean rates of

cell ingestion by post-settlement

oysters (268-651 pm in shell height)

ranged from 600 to 3000 cells h-1

individual- ' Oysters have the ability

to feed at nearly all stages of

settlement and metamorphosis.

ENERGY TRANSFORMATION, TRANSFER ANDUTILIZATION IN REPTILIAN EMBRYOS.A. Ar*, R. Drai'el, A. Belinsky and R.A.Ackerman. Tel Aviv Univ., Israel and IowaState Univ., Ames.

Fresh eggs and hatchlings of 2li tur-tles, lizards, snakes and crocodilianspecies, were analyzed for mass (H) waterand energy (E) content (c), residual yolkand E utilized during incubation (I) at27, 30 & 33°C. Reptiles resemble birds intheir high fresh egg Ec. Small fresh eggshave high specific Ec and high I wateruptake. E density of dry egg c (exceptcrocodilians) is lower than altricialbird eggs. That of crocodilians is siriii-lar to precocial birds. I is less affect-ed by Megg than in birds. The Q 1 Q effectcannnot explain I differences betweenreptiles and birds. Gross and Tot;;l Pro-duction Efficiencies are independent of Itemperature. Only Total Production Effi-ciency differs between reptiles and birds(6lt vs 57# respectively). Average frac-tion of E utilized during I is higher inreptiles (57 vs 35%): species with smalleggs utilize much more E than large eggs,which approach avian values. Thus, scallhatchlings tend to have negligible resid-ual yolk. V.'e suggest that (proportional-ly) small eggs spend more E during I, asthey expose relatively core surface areato environcer.tal stresses for a longer I.

ABSTRACTS 47A

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247 248EVOLUTION OF THE DIGESTIVE RESPONSE INSNAKES. S. M. Secor* and J. M. Diamond.University of California, Los Angeles.

The gastrointestinal response to feeding insnakes has evolved as an adaptation to feedinghabits. We found that sit-and-wait foragingsidewinders {Crotalus cerastes), Burmesepythons (Python molurus), and boa constrictors(Boa constrictor), which feed naturally at longintervals on large prey, undergo remarkablepost-feeding increases in metabolic rate (7-17fold), intestinal nutrient transport (5-1 7 fold),and intestinal mass (2-2.5 fold). Followingdigestion, their intestine atrophies andfunctionally down-regulates. However, active-foraging racers (Coluber constrictor),coachwhips (Masticophis flagellum), andbullsnakes (Pituophis melanoleucus). which feedmore frequently on smaller meals in the wild,exhibit more modest increases in metabolic rate(4-8 fold), nutrient transport (1.5-3 fold), andintestinal mass (< 2 fold), simply because theirguts do not down-regulate their function withthe completion of digestion. Our interpetationof these different responses is as follows: Forsit-and-wait foraging snakes, the atrophy anddown-regulation of the gut are selected benefitsto reduce energy expenditure during extendednon-digestion bouts, whereas frequent ingestionby active-foraging snakes dictates the constantmaintenance of a functional gut.

AVIAN RESPONSES TO UNDERNUTRITION:ADAPTIVE RESPONSE AND DEVELOPMENTALCONSTRAINT.William A. Schew, Dep. of Biol., Univ. of Penna.,Philadelphia, PA 19104

Stochastic variation in food provisioning can causedeviations from normal growth and development thatcan affect adult morphology. Growing chicks are notnecessarily passive beings during the transition fromneonate to adult and may respond to undernutrition byaltering physiological processes that reduce the impactof food shortages and enhance survival. Selectivepressures, however, may dictate no active response ifaltering developmental trajectories would result ingreater mortality risks. I examined the physiologicalresponses of European starling and Japanese quailchicks to undernutrition. Starling chicks showed nodecrease in body temperature (Tb) or BMR inresponse to food restriction and thus do not activelyreduce energy-consuming physiological processes.Quail chicks, however, showed a significant drop inTb and BMR during the restriction. This decrease inmetabolic activity reduces energy requirements duringundernutrition and I hypothesize that it is an adaptiveresponse to the unpredictable nature of their feedingregimen. I hypothesize further that the inability ofstarlings to respond actively to undernutrition is aresult of canalized development evolved in responseto the sibling competition that these nestlings face.

249IS THE CAPACITY VOW ENERGYEXPENDITURE LIMITED BY INTAKE ANDDIGESTION?K.A. Hammond*, I. Choshniak, M. Konarzewskiand J. Diamond. Univ. of California, Los Angeles,Tel-Aviv Univ., Israel and Univ. of Warsaw,Poland.

The question of what limits sustainable energyexpenditure has been of long-standing interest tobiologists. To explore tins question, we used threemodels of sustainable energy expenditure in mice(lactation, cold exposure and exercise). At peak-lactation, food intake and assimilation of mothermice increase (300% over control levels) as theirlitter size increases from 4-14 pups. Despite themothers' increase in intake, pup mass declines aslitter size increases: indicating a limit on milkoutput. During cold exposure (5°C), food intake andassimilation also increase in female mice, but not asmuch as as during lactation (100% over controls).Finally, with intense and sustained exercise (runningat 0.56 m/s, 6 h/d), food intake increases very little(10-40%) over non-exercising mice. These resultsindicate that sustainable energy output in mice isprobably limited by the capacity of output organs(shivering and exercise muscles, and mammaryglands), or by intermediary processes (liver ork:dne> metabolism, or horxuncs). and no: by th;capacity1 of the gu; to digest anu diiuruidle i.uir.t-r.ti.


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Development and Cell Biology

250 251"SURFACE MESODERM" IX PIP1D FROGS.S.B. Minsuk* and R.K. Keller Dcpl. of Molecularand Cell Biology, Univ. of California, Berkeley.

In the frog Hymenochirus cunipes, the notochordand somites form by a mechanism not previouslydescribed in any other vertebrate. Part of these tis-sues originate in the suprablastoporal epithelium.This "surface mesoderm" was once thought not tooccur in anurans as exemplified by Xenopiis laevis,in which the mesoderm derives largely from the me-senchymal deep cells, rather than from the surfacelayer. We demonstrate the existence of surface me-soderm in Hymenochirus with fluorcscently labeledgrafts showing stage-specific invasion of deep axialtissue by cells originally located in the surface layer.These cells participate in normal mesoderm devel-opment. SEM examination suggests a novel mor-phogenetic mechanism for invasion of the deeplayer. Prospective somitic cells adhere to the somiteas a coherent layer, taking on somite morphologywhile still exposed to the gastrocoelic lumen. Cellsunderlying the notochord undergo a different butrelated process. These cells individually spread onthe ventral surface of the notochord, graduallyingressing from the surface, but by a mechanism in-volving active pulling by their invasive basal endsrather than apical constriction. These processes de-monstrate that the diversity of morphogenetic me-chanism at the cellular level is much greater thanpreviously thought, even among closely relatedspecies, and that specific details of mechanism inone model species may not be globally gencraliza-ble. Supported by HD25594-5, NSF92-20525.

A MOLECULAR COMPARISON OF EARLY CNSPATTERNING IN INSECTSJ.Broadus* and C.Q.Doc (introduction by J.Camcron).Univ. o£ Illinois, Urbana-Champaign

An immediate consequence of embryonic segmentation ininsects is the formation of a two-dimensional array of neuralprecursors called ncuroblasts (NBs). The identity of each NBis determined by positional coordinates within thencurocctodcrm, which are in turn established by patterninggenes. Individual NBs are distinguished by position, time offormation, and expression of a unique set of genes. Despiteovenly different mechanisms of scgmcnuiion in ihc long-gcrmband Drosophita and the shon-gennband Schisioccrca,an anatomically similar array of NBs forms in both insccis.Here we present a molecular comparison of NBs in thesetwo insects using the expression of the sevenup (svp) geneas a marker of NB identity. We conclude that svpexpression in NBs is conserved at some spatial loci, whileother NBs appear to be positional, but not molecular,homologucs. Furthermore, we note svp expression in theunsegmented grasshopper gcrmband, an expression domainabsent from Drosophila. Prior to visible segmentation, svpexpression is seen as a broad band, and Ihcn sharpens to apair of stripes which precede and then overlap the engraileddomains. Interestingly, the initial band and subsequentstripe domains occupy a fixed position in the growinggcrmband, regardless of progressive segmentation. Thisobservation suggests a separate role for svp in earlyregionalization of the grasshopper embryo prior to usconserved expression in insect neurogencsis.

252 253ESSENTIAL FATTY ACID (EFA) AND EICOSANOICPOLYUKSATURATED FATTY ACID (P'JFA)SYNTHESIS IN EARLY NAUPLII OF ARTEMIASALINA.S.C. Wache* and H. Laufer . Dept. of Mol.and Cel l Biology, U n i v e r s i t y ofConnec t i cu t , S t o r r s .Brine shrimp n a u p l i i have high l e v e l s ofPUFAs and a re t h e r e f o r e consideredimportant in the food chain and in aqua-c u l t u r e . We examined s y n t h e s i s of theprecu r so r EFAs, 18:2 (n-6) and 18:3 ( n - 3 ) ,and t h e i r (n-6) and (n-3) p r o d u c t s . Inv i v o , us ing C - a c e t a t e , and in themicrosomes, us ing C - s t e a r a t e , most l a b e lwas recovered in l i n o l e n i c ac id (18:3(n-3) ) and in e i cosapen taeno ic ac id (20:5( n - 3 ) ) . The da ta a l s o show f a s t s y n t h e t i crates for l inoleic acid (18:2) and arachi-donic acid (20:4 (n-6)). Since l i t t l elabel accumulates in these PUFAs wesuggest that East turnover to other pro-ducts occurs. We also analyzed PUFA compo-sition during development in brine shrimpon an algal/yeast die t . We conclude thatthe dynamic changes in 18:2 (n-6) and20:4 (n-6) levels and the more constantlevels of 20:5 (n-3) and i t s precursorscan be regulated by control of syntheticrates.

FACTORS INDUCING DEVELOPMENT OFINSECT MIDGUT STEM CELLS IN VITRO.Marcia J . Loeb*: and Raziel S.Hakim' 1. Insect Neurobiolcgy andHormone Laboratory, U.S.Department of Agr i cu l t u r e ,B e l t s v i l l e , MD; 2. Department ofAnatomy, Howard Univers i ty Schooljf Medicine, Washington, D.C.During each l a r v a l molt, stemc e l l s within the midgut epithel iumof Msnduca sexta mul t ip ly andthen d i f f e r e n t i a t e between ex-isting mature gut cells, thuselongating the gut. In cultures offihole midgut from pharate fourthinstar larvae, stem cells divideand differentiate into mature;ells in the presence of 20-hy-droxyecdysone (20HE) and growthfactors derived from extract ofpreconditioned fat body. The rateof mitosis and of incorporation oftritiated thymidine by stem cellsdepends on the dose of FBX. Sim-ilarly, isolated stem cells under-go mitosis with 20HE and FBX. Butconditioned medium from developingcultures is needed for different-iation to goblet and columnarcells. The active material in theconditioned medium appears to be asmall heat stable peptide.

ABSTRACTS 49A

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Development and Cell Biology

255TROCHLEAR AND OCULOMOTOR REGEN-ERATING NERVES INTERACT WITHIN THEORBIT OF STAGE 53 XENOPUS TAQPOLES.R. F. Fangboner* and L. Burroughs.Trenton State College, Trenton.

The trochlear nerve (NIV) was cutwithin the eye orbit of the stage53 Xenopus tadpoles and allowed toregenerate. The neurite sproutswere visualized with methylene bluestaining and the sprout pattern wasdrawn using a camera lucida. Thepattern of neurite sprouts wasanalyzed using the pie segmentmethod of Kuffler. The pattern andorientation of the NIV fibers wasstudied in the presence of the in-tact oculomotor nerve (NIII), inthe absence of NIII, and in thepresence of regenerating NIII.NIV's pattern varied depending onthe status of NIII. NIII and NIVsprouts seem to avoid one another.In the absence of NIII, more NIVsprouts were found near the sup-erior rectus muscle (SRM) than whenNIII was present. This shift to-ward SRM was even greater when theSRM was bisected. NIV's and Bill'sorientation appear to be influencedat a distance perhaps by diffusiblefactors.


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THE EFFECTS OF CHRONIC TURBIDITY ANDTEMPERATURE ON DREISSENA POLYMORPHA,AND DREISSENA BUGENISIS.Summer, R.B., J.II. Thorp and J.li. Alexander*. Univ. ofLouisville, Louisville. KY.

Different groups of Dreissena polymorpha and D.bugensis were acclimated to two temperatures (15 and 25deg. C), and two turbidities using clarck type polarographicmicroelectrodes. In general, VO2 dropped at 80 NTU 30-40%. A distinct acclimation effect was seen, where the 80NTU acclimated animals had higher metabolic rates at 80NTU test conditions than did the 0 NTU acclimatedanimals. The 0 NTU acclimated animals, however, hadhigher rates at 0 NTU than 80 NTU acclimated mussels.

IS THERE GEOGRAPHICAL VARIATION INTHE THP.RMAl. TOLERANCE OF ZEHRAMUSSELS, DREISShNA POl.YMORI'HAiM.R. Hernandez* and R.F. McMahon. Univ.Texas at Arlington. Diet/., T.H. Louisiana SlateUniv., Union Rouge.

The European zebra mussel (ZM), intro-duced intu the Great l.akcs in 1986, has dispersedinto the lower Mississippi River (LMR). Innorthern Europe, the long-term upper thermal limitof ZM is 28°C. As this temperature is oftenexceeded in the LMR, natural selection has beenproposed to have produced a more thermallytolerant LMR ZM race. After acclimation to 5°,15° and 25°C. thermal tolerance times (TIT) onexposure to 33UC were recorded for 7 ZM samplesfrom LMR at Baton Rouge, LA, taken over 14March - 20 July 1994, and from the Niagara River(NR), Buffalo. NY, on 24 May & 9 August 1994.Differences in T I T occurred among acclimations^roups and the separate samples, but not betweenNR and LMR samples. 'ITT increased in 25°Cacclimated NR and LMR subsamplcs over thesampling period, but not in 5°C or 15°C acclimatedmussels. Lack of difference in TFT of NR andLMR samples suggests thai a thermally tolerantphysiological ZM race has not developed in theLMR. Rather, the natural thermal tolerance ofNorth American ZM may allow their invasion olmost freshwatcrs in the southern Unitcc'. Stales.

258 259

STARVATION TOLERANCE IN ZEHRAMUSSELS, DRICISSliNA I'OLYMORI'I'.A.Chase, R.* and McMahon, R.F. Univ. Texas atArlington.

Subsampies (n = 30) of zebra mussels (ZM)were held without food at 5°, 15° or 25"C andexamined daily for mortality. Further samples of210 mussels at each temperature were periodicallysubsarnpled (n =10) throughout the starvationperiod. Tissues and shells of sampled specimensweic dried to constant weight. ZM held at 25°Cexperienced 100% mortality after 166 days.Mortalities of 77% and 47% occurred after 402days at I5°C and 433 days at 5"C. Dry shellweight of starving ZM at 25°C or 5°C remainedconstant while, at 15°C, it increased, likely due todeposition of shell nacre without increase inlength. Dry tissue weight (DTW) decreasedlinearly during starvation with the rate of DTWloss increasing at higher holding temperatures,corresponding to tissue biomass reductions in a 20mm long individual of 73.8% after 132 days at25°C, and 68.6% and 42.3% after 359 days at15°C and 5°C, respectively. When DTW' lossrates were converted to O2 consumption rates(Vo2), the Vo2 of a 20 mm long mussel wasestimated to be 22.2Si of prestarvation Voj at25°C, 11.0% at I5°C and 10.1 % at 5"C. Majorreduction in metabolic demand in starving ZM atlow temperatures allows overwintering withoutappreciable loss of organic energy stores.

EFFECTS OF ELEVATED CO, LEVELSON SURVIVORSHIP IN ZEBRA MUSSl-LSAND ASIAN CLAMSR.F. McMahon* and M.A. Matthews. Univ.Texas at Arlington.

Three replicate samples (n = 30) of zebramussels (ZM), Dreissena polymorplia, and Asianclams (AC), Corbiadu flumineu, were exposed tomedia at 25°C and pri « 6.0-8.0, bubbled withCO:, N2 or air. Deaths were recorded every 12-24h until 100% mortality was achieved. Nomortality occurred in air bubbled media with eitherspecies. Mean mortality time (MMT) in ZMexposed to N: was 103.7 h (s .d=±49.8) and inAC, 349.7 h (±78.2). Mortality was more rapidamong CO2 exposed samples; a MMT of 43.6 h(±15.5) recorded in ZM and 46.3 h (±7.1) inAC. Estimated time for 50% sample mortality(LTM) for ZM samples ranged from 75.9-90.4 li inN, and 26.0-32.7 h in CO:. Corresponding valuesfor AC were 306.5-349.4 h and 32.7-40.3 h,respectively. Multiple ANOVA indicated nodifferences in MMT of replicate samples of eitherspecies or correlation of MMT with shell length(P>0.05). In contrast. MMT values in both N,and CO2 treatments were greater in AC than ZM.In both species exposure to CO2 was more lethalthan exposure to N2. These results indicate thatinjection of CO2 may be an easily applied andcost-effective strategy for control of macrofoulingby both species.

ABSTRACTS 51A

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260 261

THE INTERACTION BETWEEN PHYSIOLOGICALCONDITION AND REPRODUCTIVE PATTERN INTHE ZEBRA MUSSEL DREISSENA POLYMORPHA.D.R. Den.son, C.C. Sun and S.Y. Wang'.'Univ. ofSouthern Missis.sippi, Hattiesburg.

The relationship between physiological condition andreproductive pattern in zebra mussels was studied usingmonthly biochemical composition analyses andhislological examinations. Mussels were collected fromthe Niagara River in Buffalo, NY, starting Feb 1992and continuing for 22 months. Mussels collected in Feb1992 were in relatively poor condition; mean glycogenconcentration was 35.9 + 5 2 jtg/mg dry wt (n = 18).Gamete synthesis peaked in May 1992. Zebra musselsremained in good condition throughout the winter of1992-93; the minimum glycogen concentration, 101.0+ 9.5 jig/mg, was reached in Oct 1992 after which itincreased steadily until the following March. Gametesynthesis was delayed during the following spring anddid not peak until July. Hislological observations alsoindicated a delay in spawning. Our results suggest thatthe condition of mussels during the winter affects thereproductive pattern the following year. When zebramussels are in poor condition during winter, gametesynthesis is initialed eaily, the period of synthesis moreabbreviated and the reproductive season shorter duringthe following spring and summu". When mussels are ingood condition during the winter, gamete synthesis isdelayed and the reproductive season extended.

CURKICNT VELOCITY HH'HCT.S ON ZliliKAMUSSEL BYSSAl.THKIiAD PKODUOT1ONM. Clarke" and K.I'. McMahon. Univ. of Texasat Arlington.

Zebra mussels, Pmxsciuipiilynioijyha wereallowed to make initial byss.il attachment (3 24threads) to 14 s 14x2 unit clear plastic plates anilexposed to cuncnt flows of 0.1, 0.15, 0.2 and0.27 m/s at 2.VC for 21 days. Plates wereremoved daily and the number of byssal threadsproduced by indivdua! mussels counted. At allfour flow rate;., mussel;, produced byssal threads atrelatively constant, but dil Cerent rates, for the first11 days, llierealler thread piodtiction rale wasreduced, but roughly equivalent among the fourtreatments. Repeated measures multi-factorANOVA indicated that byssal thread productionrale was correlated with initial thread number andshell lenglh and affected by current velocity. Theleast number of threads were pioduced at thelowest velocity (0.1 m/s) increasing to a maximumat 0.2 m/s. At the highest velocity of 0.27 in/s,it decreased to levels equivalent to those iccordedat 0.1 and 0.15 m/s. The data suggests that Howrales above the relatively low level of 0.2 ni/sccreduce the rate at which mussels form firm byssalattachment. Inhibition of byssal attachment rate inlow current flows may be the basis for this speciestendency to accumulate preferentially in low flowrclugia such as substratum cracks and devices oramongst conspeeific mussel aggregations.

262 263

DELAYED METAMORPHOSIS OF QUAGGAMUSSEL LARVAE MAY ENHANCEGEOGRAPHIC SPREAD.B.S. Baldwin. Rutgers Univ., NewBrunswick.

The duration of the dispersive larval phaseof quagga mussels (Dreissona bugensis) wasinvestigated in the laboratory. Most (62 %)pediveligers metamorphosed to juveniles asearly as 15 - 26 days post-fertilization.However, of the remaining pediveligers, 73% delayed metamorphosis for more than 21additional days; 50 % delayed for more than44 additional days; and 23 % delayed for over50 additional days. During these apparentdelay periods, these larvae were capable ofactive swimming but spent a decreasingamount of time doing so. These resultssuggest that actively swimming larvae candisperse for about 2 - 3 weeks prior tosettlement but pediveliger activity mayextend dispersal for an additional 7 weeks.This capacity for delaying metamorphosismay promote the spread of quagga mussellarvae over wide geographic regions,particularly via transport in ship ballastwater and downstream advection in rivers.

ABUNDANCE, NATURAL MORTALITY, AND THEPOTENTIAL FOR PREDATOR-MEDIATEDBIOLOGICAL CONTROL OF THE ZEBRA MUSSEL.L.C. Boles* and R.N. Lipcius. College of William andMary, Virginia Institute of Marine Science, GloucesterPoint.

The success of introduced species like the zebramussel, Drcissena polymorpha, is due in pan lo ineffectivepredators in ihe newly colonized systems. We conducted aseries of descripnvc and manipulative experiments aimedat quantifying ihe abundance, natural mortality, andeffectiveness of predators in controlling the invasion ot thezebra mussel in ihe Hudson River, New York.Predator-exclusion experiments indicated that populationregulation by the local predator guild (several finfishspecies) was unlikely. However, trials with introduced bluecrabs, Callincctcs sapidus, suggested that the zebra musselmay be regulated in habitats where the blue crab isabundant.


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POPULATION STRUCTURE. FEEDING ANDREPRODUCTIVE BEHAVIOR. SUBSTRATUMSELECTION, AND PREDATION OF UCA PUGNAXAND UCA PUG1LATOR IN THE MARSHES OFHUNTING ISLAND, SOUTH CAROLINA.G. A. Croll* and T. S. Klmgcr Bloomsburg Univ. ofPennsylvania, Bloomsburg.

Uca pugnax and Uca pugilalor both inhabit the marshesof Hunting Island, South Carolina. Each species maintainsapparently healthy populations. Both populations exhibitclumped distributions. However, the occurrence of onespecies is not contingent on the other. Within the marshthere exist O|KMI areas devoted to mating behaviors (lcks)where the densities, sex ratios, and age-class structuresdiffer from the populations of U. pugnax and U. pugilaloroutside the open areas. Both species exhibit similarbehavioral repertoires. The time spent at individualbehaviors differ between U. pugnax and U. pugilalor.Large male U. pugilmor spend more lime in courtshipwaving than large male U. pugnax. For both S|)ccics, largemales spend less time feeding, more time resting, and moveless distance than females or small males. Fecdmg-nichcbreadth indices for utilization of substratum particle si/csarc large and similar for U. pugnax (FT=O 996) and U.pugilalor (/-T=0.994). Feeding-niche overlap is moderate(L=0.483). Uca pugnax selects sediment grain sues inpioportion to their availability. Uca pugilalor sclccLs largersediment grain sizes while feeding. Analysis of Procyonloior scat, indicates selection for small male and femalefiddler crabs in prcfeicncc to males with large claws.

Tl IB EFFECTS OF DEP 1"H, WATER FLOWAND DIET ON SETTLEMENT,RECRUITMENT AND GROWTH OF THEGREEN SEA URCHINSTRONCYI .OCF.NTKOT1 ,'SPKOERACIMENSIS.L.G. Harris. Univ. of New Hampshire, Durham

Studies of early benthic phase populationsof the green sea urchin S. drochaehiensis in thesouthern Gulf of Maine have demonstratedconsistent patterns of settlement over a 12-yearperiod, but much variation in recruitment andgiowih. Settlement density decrease; withincreasing depth and also is reduced in areas oflow water exchange. Survival of urchins pastthree months is spatially and temporallyunpredictable, though it may improve withincreasing depth. Growth rates are also highlyvariable within populations and growth is beston an omnivorous diet. Water flow also appearsto have a positive effect on growth rates.Urchins reach sexual maturity at about 25mm indianietci and well-fed urchins may teachliars L-Mabie size of 50mm in about tv.o and one-half years. The implications for management ofan urchin fishery in the Gulf of Maine arcdiscussed.

266 267

LARVAL DISPERSAL OF PELAGIC VELIGERLARVAE OF INTERTIDAL NUDIBRANCHMOLLUSCS WITH CONTRASTINGDEVELOPMENTAL STRATEGIES.W.J. Lambert* and CD. Todd. Univ. of NewHampshire, Durham and Gatty Marine Lab, Univ oSt. Andrews, St. Andrews, Scotland.

The population genetics of the inicnidal doridnudibranchs Goniocloris nodosa and Adalariuproxima were studied over a 1500km range of thenorthern British Isles with the objective of assessingthe realized dispersal of contrasting larval types. F-statistics of clectrophorctic data suggest thatpopulations of G. nodosa (planktotrophic larva) svennot differentiated; in contrast, for A. proxima(Icethiirophic larva) there were exceptional levels ofgenetic differentiation. On a minimum geographicscale significant levels of genetic differentiation ofpopulations of A. pioxima svere consistently foundover distances as little as 100m. The minimumiealizcd dispersal distance of the larva of A. proximawas assessed with transplant experiments. Yellownudibranchs from Olda.ny Island svere transplantedinto a population at Kylcsku Bridge that previouslyonly contained svhite nudibranchs. There was astrong association (p<0.000002) between theincidence of the yellosv phenotype and the presenceof a genetic marker in juveniles at Kylcsku Bridge inthe following generation. Such levels of geneticdifferentiation indicate that whereas planktoirophiclarvae may be transported over distances of 100-1000km, dispersal of lcckhoirophic larvae of A.proxima from the parental source docs not occur.

0 ^ASSOCIATION OF CKOWTIi RATii FROM LJiMUTIIOF LARVAL LIFE BY STARVATION IN CKEPIDULAFOKNICATA. J.A. Puchenik*, S. E s t r e l l a ,K. il;jir.i..er, and C. Keise . Tufts Univ. ,Kedford, M\.

I t i s commonly assumed chai when foodconcen t r a t ions arc low, l a rvae w i l l growmore slowly and requ i re more time to de-velop in the plankton. in th ib s tudy , wesought to determine the ex ten t to whichlength of l a r v a l l i f e could be uncoupledfrom growth r a t e . Larvae of (J. forn ica tawere reared a t 25°C on phytoplnnkton for4-6 d and then starved in filtered sea-water. Starved larvae continued to at-tain metamorphic competence for up to sixdays after shell growth stopped, asassessed by periodic exposure of larvaeto excess K+. In other experiments,starved competent larvae ini'tauiorpliosedsponuineoti:;!y nuout 10 d sooner Llum didcompetent larvae from the satr.c culturethat were fed throughout development.Time to metamorphj.c competence and spon-taneous ir.etarcorphosis were not inverselyrelated to rates of energy acquisitionand not well predicted by growth ra te .

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268 269C O M P A R A T I V E P O P U L A T I O N G E N E T I CSTRUCTURES OF TWO RECENTLY DIVERGEDSPECIES OF PROSOBRANCH GASTROPODS: THEIDENTIFICATION OF PLEISTOCENE REFUG1A ANDASSESSING THEIR ROLE IN ALLOPATRICSPECIATION. Marko, P.B. University of California atDavis.

The fossil record suggests climate change causeslatitudinal shifts in the geographic ranges of organisms.Latitudinal shifts may also result in the fragmentation ofdistributions, providing opportunities for geographicisolation and speciation. Although climate-driven speciationis proposed for organisms inhabiting north-south coastlines,few data test this hypothesis. A species recently formed ina refuge should exhibit a modern population geneticstructure and intraspecifle phylogeny which is qualitativelydifferent from that expected under a traditional vicariantscenario. I have comparatively analyzed the populationgenetic structures and intraspecifle phylogenics of tworecently diverged species of prosobranch gastropods,Nucella emarginata'northern' and N. emarginala'southern'.Genetic data suggest that the 'southern' species is derived,and that it recently expanded its geographic range from arefuge in Baja California. Morphological data arcconcordant with this hypothesis. However, temporalcorrespondence between a bottleneck and spcciaiion isdifficult to determine unless fossils arc available, as well asa knowledge of ecological and environmental conditionssince speciation.

EVOLUTIONARY PATTERNS OF RADULARCUSP SHAPE AND DIET IN LHT0R1NAD.E. DITTMAN. University of Wisconsin- Madison., Madison, WI.

Tests of correlated evolution of speciestraits taking phylogeny into account allowgreater insight into the evolutionarysignificance of the traits and are morestatistically valid than simple correlationanalysis. 1 used a method of phylogcncticallyindependent contrasts to test the hypothesisthat the shape of the rachitlial cusp isevolulionarily correlated with diet in the genusLitiorina. Using this method I could separatethis hypothesis from alternative hypothesesthat trait correlations are a function of groupphylogcnctic history and are not necessarilycurrently adaptive. The shape of the centraltooth was found to be significantly correlatedwith the size of algae in the diet (N=13,P=0.005). Pointed cusps are correlated withconsumption of large macroalgae. Bluntcusps arc correlated with the consumption ofmicroalgac and diatoms. Phylogenelic historyonly had a small contribution to thecorrelation. This result is considered in thephylogcnctic context of the Littorinidac.

270 271

SLITS, SIPHONS, AND HOLES: FLUSHING OUTTHE PROSOBRANCH MANTLE CAVITY.J. Voltzow* and R. Collin. Univ. of PuertoRico, Rio Piedras, and Univ. ofWashington, Seattle.

A central dogma o£ the biology of. theGastropoda is that sanitation was thedriving force in the evolution of theslits, tremata, and apical openings ofthe shells of early gastropods. Ucexamined the mantle cavity morphology andrespiratory flow o£ D-'odora aspera(Fissurellidac) in which the apicalopening was naturally or experimentallyblocked. V.'c found no evidence of danageto the mantle cavity or associated organsAlthough the apical opening is notnecessary for sanitation, it is necessaryto induce passive flow through the raantlecavity and nay improve the dispersal ofganetes. Similar patterns of flowobserved through the rrantle cavities ofHaliotis kantschatkana and Perotrochusraaueri strengthen the hypothesis thatthese latter functions and not sanitationwere the selective advantages of slit andperforate shells. (Funded by L'PS-FIPl.)

FUNCTIONAL SHIFTS IN GASTROPODSHELL MORPHOLOGY ATMETAMORPHOSIS.C.S. Hickman. University of California,Berkeley.The metamorphic transition from larval tcjuvenile life in marine gastropods is presen'ed ir.the shell as a sharp boundary between protoconcrand teleoconch. At least four distinct secretoryshifts may be recorded: (1) change in theconfiguration of the apertural margin, (2) changein the pattern of surface sculpture, (3) change ircalcium carbonate microarchitccture, and (4;change in the direction and geometry of shellgrowth. The functional significance of some olthese shifts is inferred from analysis of alternativefunctional paradigms, direct observations of larvaland juvenile function, and experimentalmanipulations of morphology. Although thetransition is generally assumed to be sudden andto correspond to the onset of metamorphosis,studies of prosobrancli veiigcr larvae reveal somesecretory shifts that are staged, some that precedesettlement, and are others that occur after the lossof the velum. Shifts that are most easilyinterpreted are the loss of larval shell features thatprovide mechanical support for larval structures ormechanical resistance to predation in the planktonand features associated with the transition in taxathat become scdcr.iury following metamorphosis.Studies of the transition are providing new datafor use in phylog:re:;c r-.-p.!v<i'=.

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A COMPARISON OI-" PIIANYNCil-.Al. Hli'iNC.MECHANICS IN S I N i i S I Il-.S AND CICI II.IDS.IMPLICATIONS; ()1: A S T U l C T l l s A I . AN 13FUNCTIONAL in -.corn. ING.F. Galis, E.G. Diuckcr. Umv of Lculcn (IhcNetherlands) and Haivard Uni\cisil). Cam, MA.We pro|X>sc a mechanical model ol phaiyngcal bilingin sunfishes, a I'amiU of non-labroid pciciformfishes (TclcoMci: Ccnlraichidac). The model i.s basedin part on an earlier model b\ Wainwiighl on bilingin the Hacmulidac. New and central in our model is astructural coupling between the upper and lowerpharyngcal jaws which allows their simultaneousmovement upon contraction ol" the upper jawmusculature Electrical stimulation ol" individualpharyngcal muscles icsullcd in coupled movement olIhc uppci and lowei jaws in ccnlraichids andindependent imncmcnl of the jaws in cichlids Wesuggest that ihc tiansrormation ol ihc pcicifoimpharyngcal biling mechanism fmm Ihc basalcondition exemplified b) ihc Ccnliaichidac to ihcdemed (labioid) condition ol Ihc Cichlidac hingedupon Ihc modilicalion ol six phanngcal sliucluiesThe key innovation in ihc development of Ihcfunctionally \cisalilc labioid phaiyngcal jawapparatus was Ihe decoupling ol cpibianchials 4fmm Ihc upper phaiyngcal jaws The liansfoimalionof the phanngcal biling mechanism in IhcPeiciloimcs is an excellent example of a decouplingof slructuics associated uilli a dueisilicalion ol loimand function and with ma cased spcci.ilion laicsSuppoilcd bj a FulbiiglH Icliowship and a NVVOgiant

IN I RA- AND INTERSPECIFIC VARIATION INPREY USE AND FEEDING BIOMECHANICS INCARIBBEAN TETRAODONTIFORM FISHESR.G. Tunngan" and P.C. Wainwngh;Florida State Univ., Tallahassee.

The relationships between prey utilization and jawbiomechanics in tetraotiontiform fishes wereinvestigated a: two levels (1) at the intraspeciliclevel, two populations (Mona and La Parguera) offour balistoid fishes were compared; and (2) at theinlerspecific level, six species, co-occunng at LaParguera were compared. The volumeinccontribution of major prey types and threebiomechanical features of the lower jaw thatcharacterize biting strength were contrasted withinand between species. Both interpopulation(intraspeciiic) and inlerspecific comparisonsrevealed differences in diet lhal wore associatedwith differences in trophic morphology. Featuresthat enhance the production of strong biiing forces,such as robust jaw adductor muscles and bones,and high jaw closing lever ratios, characterized fishthat fed on hatd prey. In contrast, fish that ale softprey had thin jaw muscles and bones, and low |awclosing lever ratios, indicating the production ofweak biling forces. The biomechanical al'.ribulesthai underlie tiophic diversity in tetraodontiformfishes appear to show substantial developmentalplasticity, possibly enhancing the ability of speciesto succeed in habitats that vary in the available prejbase

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BEHAVIOR I.S MORE IMPORTANT THANMORPHOLOGY IN PRF.DICTING DIET OFTWO SPECIES OF HEXAGRAMMOS(THLHOSTEI- SCORPAEN1HORMES)Ncmclh, D. I larvard Lnivcrsiiy, Cambridge MA.

Kelp grecnling (KG; H. clc-eaarammu'O aicUIIK|UC among fishes of the North Pacific in thatthey prey heavily on sea cueumbeis and other largepicy that cannot be swallowed whole. Ii wasexpected that kelp greenling might differmoiphologically from whitespotled greenling(WSG; H. Mejlcri), a co-occurring species notknown to bile pieces from large, lough prey items.Comparison of jaw adductor muscle size and jawclosing lever arms produced an estimate of bilefoive lhal did not differ between the two species,tooth shape was identical for the iwo species fiitcforce increased linearly with fish size, fillingperformance was leslcd using strips of squidclamped lo ihc aquarium wall. KG wcic moresuccessful in biling off pieces of squid than WSGol similar size. When wider squid strips wereoffered, W.SG switched to rotational feeding(spinning) wheicas KG were still successful usinga tearing motion. Spinning is energetically costlyand increases visibilily of the predator. This switchto spinning and a relatively lower feeding successis associated with the absence of large prey items indie diet of WSG. '1 hesc data show that differencesin feeding behavioi contribute more than jawclosing morphology to the observed difference indici.

DO ALL FLATFISH FEEDASYMMETRICALLY? KINEMATICS OPPREY CAPTURE IN Xyxtrenryx holepix.A. C Gibb. University of California, Irvine.

Variation in the degree of cephalic asymmetryamong flail ish suggests that the head and jaws ofdiffeienl species may be adapted for differentmechanisms ol prey capture. In lliis study, picycapture kinematics of a flalfish with liltle cephalicasymmetry. Xyxlrcnrys liolepis (I3ollndac). wciequantified and compared with data collectedpreviously for a more asymmetrical flatfish,Plciimnicliihyx veiiictilix (Pieuroneclidaej. FourX. liolcjiis were video-taped feeding using a two-camera video system at 250 fields per second.Prey capture was rccoided from three views; 1)ihe eyed (ocular) Mdc, 2) ihc blind side, and 3)the gular region. A pieliminaiy anal)sis indicatesthat X. liolc/iix possess fewer functionalasymmetries during prey capture than P.vcrticalix. Unlike P. veriicalix. X. holepixachie\c the same maximum gape on the blind sideof the head as on the ocular side, can flex theirheads toward the ocular or blind side (dependingon the position of the prey), and do not producelateral bending of the jaws out of the sagittal planeJuring prey capture. These results appear losupport the hypothesis that cephalic asymmetry i.sfunctionally related lo capture behavioi inflatfishes.

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FUNCTIONAL CONSEQUENCES OF TROPHICSPECIALIZATION IN PUFFERFISHESRebello, K.R.Florida State University, Tallahassee, Florida.

A common ecological hypothesis states that trophicbreadth is correlated with functional versatility. As acorollary, specialists should show reduced ability to alteior vary their motor patterns as compared to generalistswhen feeding on different prey types. I examined preytype effects on patterns of muscle activity in two speciesof pufferfishes: Chilomycterus schoepfi, a specialist onhard shelled prey, and Sphoeroides nephalus, ageneralist predator. Electromyographic recordings offive muscles used in feeding weie made from fiveindividuals per species feeding on four prey types thatvaried in their hardness and escape abilities. Muscleactivity duration, relative onset, and rectified area wereanalyzed for prey capture and manipulation behaviors.Prey type effects on mean motor pattern variables forcapture were limited to one of eleven variables forC. schoepfi and one of ten variables for S. nephalusPrey effects on manipulation were only significant in twoof twelve variables for C. schoepfi and three of ninevariables for S. nephalus. However, overall motorpattern variability was significantly different amongspecies, with C. schoepfi, the dietary specialist,exhibiting greater motor variation. Based on thesespecies, it appears that there is no relationship betweendietary breadth and functional versatility. Thus, thepredicted correlation was not found, suggesting thatdifferences in diet have a basis in some aspect otherthan motor pattern flexibility.

ONTOCUNY 0 1 ' FlCKDINi; HICIIAVIOK IN

UK K.IO.IJ. I* Hernandez, l l a rva id University,Cambridge. MA.

While there exist.-* ;in extensiveliUnature describing ihe feedim; behavior ofnilult tolcosts, relatively few researchers haveexamined feeding mode and capture kinematicsin larval fish. ['VedniR performance in larvalfish is a trail for which selection is .strong,given (bat. starvation ensues soon afterresorption of the yolk if fecdine does not. beginimmediately. Tins study i.s an onloerenelicanalysis of feeding behavior in (he /.ebrafisbduring: a Uvo week period following yolk sacresorption. Through the use of high speedvideo (1(100 lie.), individual fish were filmedfrom both a Literal and dorsal aspect. Lateralviews wore used to quantify attack kinematicswhile dorsal views were used lo evaluatefeeding mode Suction feeding was ,\\\important mode early in onUigeii) ixnvReynolds numbers experienced by these fishbad interesting implications on feeding modeand kme.mal.ios.

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MOTOR LEARNING IN TOADS (Bufomarinus) FOLLOWING HYPOGLOSSALTRANSECTION.CM. Innocenti* and K.C. Nishikawa.Northern Arizona University, Flagstaff.

In toads, transcction of the hypoglossalnerves inactivates the tongue protractormuscles and prevents mouth opening byinterrupting sensory feedback. Thepurpose of this study was to test whethertoads learn to compensate for thesedeficits, and to describe the pattern ofmotor learning. Toads (n=5) werevideotaped during feeding attempts for upto 5 weeks after bilateral hypoglossaltransection. Changes in performance andkinematic variables over time weremeasured for each toad. Before surgery,capture success was nearly 100%,whereas after surgery it fell to 0%, andthen increased back to 100% within 5-6weeks. Duration of jaw and tonguemovements were unaffected by nervetransection. Toads learn to compensate forlack of tongue protraction by increasinghorizontal and vertical head movementsand gape angle. These resultsdemonstrate that toads have the ability tolearn new motor tasks within as few as 44trials over an 8 day period.

MODULATION OF PREY-CAPTURE A MODEL FORTHE EVOLUTION OF TERRESTRIAL FEEDING INSALAMANDERS.R.A.Pylcs* and A M . Maglia. East Tennessee Stale Unix.and The Univ. of Kansas

In a kinematic study of prey-capture. Plethoclon cmcreus(Urodcla. Plclhodontidac) modulated feeding modes amongdifferent prey tjpes. An hypothesis of ihc stimulus-responsepathwajs among alternate modes is proposed Distinctivecombinations of tongue protrusion, jaw prehension, and bodymovements characterize different modes. Elicitation offeeding is affected by prey and salamander sizes, but preyactivity is the primary determinant of the initial prey-capturemode Variation in gape, lime for tongue retraction, andpresence of a fonvard body lunge suggest that mechanicalfeedback from peripheral structures m contact with preyserves lo niodifS feeding behavior during the feeding event Ifa repertoire of prc)-capture modes is generalized (andpotentially plcsiomorpluc), the hypothesis proposed producesa model that predicts pallma\s for the c\oiulion of terrestrialfeeding specializations in plcthodontid salamanders.Specializations to capture small, fast-moving prey may haveoriginated with reduction of visual responsecness to large orslow-moving prey, thereby providing selective pressure toenhance the cfiecmcncss of morphological structures (i.e..tongue projection) in capturing prc> at a distancePredictions from this model arc in accord with results fromprevious studies on \isual systems and feeding Kinematics ofother salamander species A similar paradigm incorporatinga generalized repertoire cf prey-capture behaviors ma\ beuseful n describingthe nc^iticn oricrrC5tn.il pre> cnplurc in

C.Wul &,.laUlu:.U*:i3 PthJ^UVC S.iijil.onu.:!:* ill.'.) ii.KC

exhibited not one. but 111611). modes of prey capture.

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SCALING OF FEEDING KINEMATICS ACROSSFOUR SPECIES OF DENDROBATID FROGSE B Wiltcnmuth * and K C Nislnkaua NorthernArizona University. Flagstaff. AZ

Physiological characteristics often scale withbod> size, but few studies have examined theeffects of bod> size on feeding beha\ior Thisstudy tested the effect of body size on feedingkinematics across four closely related species ofdendrobatid frogs Dendrobates rcticulatus (n=l).Dcndrohatcs aurains (n=7). E^rieilobates tricolor(n=3). and Ph\ llohalcs bicolor (n=4) Jan lengthsranged from () 32-0 XX cm Using high speedvideogiaphs. frogs weic filmed eating fruit flies,and 1-3 feeding sequences were anaKzed for eachfrog Duiations. angles, velocities, and distanceswere measuied from each feeding sequence AnANCOVA with jaw length as the covanate wasused lo test for effects of species and size Many\anables showed independent effects of size and/oispecies on feeding kinematics Several variablesshowed species*size interactions To lestpredictions of isometric scaling, kinematicvariables were regressed with jaw lengthInterspecific regression equations did not follow allpiedictions of isometric scaling For somekinematic variables, slopes diffeied among speciesAllometric changes max be related to differences indiet or foraging modes among species

MECHANICAL PROPERTIES OF BAT WINGMEMBRANE SKIN.S. M. Swartz", M. S. Groves, H. D. Kim And W.R. Walsh. Brown University, Providence, RI andUniversity of New South Wales, Sydney,AUSTRALIA.In baLs, skin functions as a primary locomolororgan. While fiber bundles in most mammalianskin are oriented randomly, the predominantorientation of these bundles in bat wings is in anetwork of approximately orthogonal crossedfibers. We predicted that bat wing membranes arehighly anisotropic as a result ,of this arrangement,and that the variation in mechanical characteristicsassociated with this connective tissue aichitcclurerelates to differential requirements for skin functionalong different axes of the wing. To test thishypothesis, we carried out materials tests on skinsamples from tiie plagiopalagium, daclylopatagiumand uropatagium of 7 microchiropteran species.We found that the mechanical performance of batskin is significantly different from all previouslystudied taxa in important ways. Wing membraneskin i.-. highly anisotropic, with significantdirectional variation in clastic modulus, failureload, failure stress, yield strain, and energyabsorbed before failure. Stiffness and strength arcgreatest parallel and failure strain is greatestperpendicular to the bones. Skin from distinctanatomical wing regions also differed significantlyin mechanical characteristics; strength and stiffnessaie greatest in the tail membrane, and least in thedaclylopatagium, near ihc wing tip.

282 283

WING SHAPE SCALES ISOMETRICALLY BETWEENMALE AND FEMALE BIG BROWN BATS

The Big Brown Bai, Eptesicus fuscus, shows clinalvariation in litter size (2 young/litter cast, 1 young/lmeiwest). Due to the aerodynamic constraints imposed bygreater fetal mass, I hypothesized that the wings of femalesfrom the east will be proportionately larger (whencompared to their resident males) than females from thewest. Contrary to Ihe prediction, western bats (both sexes)were larger than eastern bats. Therefore, in this species,carrying different numbers of offspring has not influencedthe evolution of wing size. In addition, I found no shapedifferences between the sexes at cither locality. Since batsshow reversed sexual dimorphism (females larger thanmales), the lack of shape difference between the sexesimplies lhat female wings are isometric enlargements ofmale wings.

THE SCALING OF INTERMITTENT FLIGHTBEHAVIOR AND WING MORPHOLOGYIN WOODPECKERS.B.W. Tobalske. Univ. of Montana, Missoula.

Using laboratory and field techniques, I studiedintermittent flight in six species of woodpeckers(body mass 27 - 260 g). During level flight, allof the species exhibited flap-bounding. Speedand percent time spent flapping were independentof body mass, but the number of flaps betweennon-flapping phases scaled as mass ("°-47). Five ofthe species flew at approximately 9 m/s whereasLewis' woodpeckers flew near 7 m/s and flappedmuch longer between bounds than the others. Thisspecies was also the only one to engage inprolonged glides during foraging flights.

Contrary to prior reports, external and internalwing dimensions were geometrically similaramong species. However, the fiber composition ofthe pectoralis muscle changed with body mass.The pectoralis muscle in woodpeckers less than100 g in body mass was composed mostly ofRed (R) fibers with Intermediate (I) fibers absentor restricted to lateral regions. Species larger than100 g had R and I fibers throughout the pectoralis.This scaling of muscle composition may explainwhy species larger than 100 g flap-bounded whentheory predicts they should not have sufficientpower. Intermediate fibers in the Lewis'woodpecker were unique in staining intenselyfor glycolytic potential - perhaps reflecting theirforaging flight style. (Sigma Xi GIAR 9206)

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FLIGHT MORPHOLOGY, PERFORMANCE,AND PREY CAPTURE BEHAVIORS IN AGUILD OF AERIAL INSECTTVORES.D. R. Warrick. Univ. of Montana, Missoula.

The flight morphologies, flightperformance, and prey capture behaviors of twospecies of swallows and two species of swiftwere examined in a study of foraging ecology andits morphological correlates. Wing and tailloading and shape were measured on live animals,and the brachial and antebrachial musculoskeletalanatomies were examined ip museum specimens.Flight speed, acceleration, and roll (banking) ratewere measured using 3-d video reconstruction ofthe birds' flight paths as they were released in afield portable flight corridor. Prey capturebehaviors such as maneuver used in prey captureand the use of wings and tail were quantified fromvideo. Barn Swallows have lower wing loadingsand higher aspect ratio wings than CliffSwallows, and more frequently use brief, highangular acceleration rolling and pitch-upmaneuvers augmented by die tail during preycapture, while Cliff Swallows use hawkingflights from a gliding perch. Though the White-throated Swift is relegated to high speed foragingdue to high wing loading and restricted wingkinematics, its large aerodynamically optimal tailis used to enhance agility and maneuverability,serving as a high lift device or brake during preycapture; in contrast, the aerodynamicallycompromised tail of the small, lightly wing loadedVaux's Swift is rarely used in flight.

BILATERAL FORCE RECORDINGS OF THEWINGS OF PIGEONS DURINGMANEUVERING FLIGHT. K.P. Dial*,D. Warrick, and A.A. Biewener. Univ. ofMontana, Missoula, and Univ. of Chicago.

In an effort to elucidate the biomechanics andncuromuscular control associated withmaneuvering flight in birds, we studied thicetrained pigeons flying an obstacle course. As thebirds turned around barriers, flight kinematics(from high-speed film and video), muscle activity(from bilateral EMG implants), and feather strains(from midshaft primaries) were simultaneouslyrecorded with strains of the deltopectoral crest(DPC) and humeral midshaft. DPC strains werecalibrated in situ using a force transducer. Duringturning flight, wing asymmetry is primarilyachieved by asymmetrical activation of brachial(biceps & humerotriceps) and antebrachialmuscles of the wing (Dial and Gatesy, Amer.Zool., 33:24A) and apparently not by differentialforce production by the two pectoralis muscles.EMG intensity appears to be a good indicator ofrelative force output since EMG intensities(rectified and integrated) tracked closely withvarying strains during all flight modes (takeoff,level-flapping, landing, and maneuvering).(NSFIBN-9211393)

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AVIAN LONC CONH MORPHOLOGY: LOCOMOTORCORRELATES OF LIMB SHAPEK.D. Earls Brown University, Providence, RI

We know little about overall patterns of skeletalscaling of birds or the relation of avian bone scaling tolocomotion. Previous investigations have been limitedin focus or eclectic in sample composition. To date, ithas not been determined whether modification of wingor hindlimb is more important to differences inlocomotor repertoire, although increases in hindlimblength with terrestrial specialization have beendocumented. Bi-plannr radiographs and/or externalmeasurements were collected of all nu|ur limb bones of93 species, spanning 8 families. Scaling of bonedimensions do not differ significantly among families.However, functional groups, defined by behavioral andecological criteria, differ morphologically. Hindlimbmorphology is -i.i-iilar across functional groupings andall show comparable patterns of morphological changewith size. Forelimbs of flight oriented birds (thosewhich spend more time flying; or in trees than on theground) have significant!) elongated ulnae and hadincieased bending Miength for all wing bones (asestimated by second m..ment (.!* area). Cn a brrad scale,modification t.i fnrchrr.b skeletal rr.prplmhigv is mnrestrongly correlated to locomutor mode in birds than is

BIOMECHANICS OF CRANIAL KINESIS INBIRDS: TESTING LINKAGE MODELS INTHE WHITE-THROATED SPARROW.W.J. Hoesc* and M.W. Westneat. DukeUniversity, Durham, NC. Field Museum ofNatural History, Chicago, IL.

Cranial kinesis in sparrows is the rotation ofthe upper jaw around its kinetic joint with thebraincase. Upper and lower jaw movements maybe coupled through the postorbital ligament.Alternatively, jaw motions may be uncoupled,with the upper jaw moving independently of tiielower jaw. We present a biomechanicul model ofjaw kinetics that predicts the motions of the. jawsfor both a coupled and an uncoupled mechanism.The model is based on the mechanics of fojr-barlinkages and lever systems, and usesmorphometric data on cranial structure as thebasis for predicting cranial movements.Predictions of cranial motions are tested bycomparison to kinematics of the white-throatedsparrow fZonntnchia alhicollisi during singing.We conclude that the upper and lower jaws arenot lightly coupled in white-lhroa:ed sparrows.Variation observed in jaw motions during song isconsistent with the model in which independentcontractions of upper and lower jaw musclescontrol beak motion. Supported by PHSDC00402 to S. N'owicki and NSFIBN' 94-07253to M. Westneat.

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288 289FUNCTIONAL MORPHOLOGY OF Til!-: UNIQUEFEEDING AND SEED-SHELLING MECHANISM OFTHE AUSTRALIAN GLOSSY BLACK-COCKATOO,CAI.YPTORHYNCHL'S LATHAM!.D.G. Hombcrgcr*, G. Chapman, and R. Schoddc.Louisiana State University Baton Rouge, and CSIRODiv. of Wildlife & Ecology, Canberra.

Calvntorhvnchu'. l.itlinmi differs fundamentally fromother rcd-tailcd Black-Cockatoos in its ecology, feedingmechanism, and bill morphology. It occurs in nativeforests along the eastern coast of Australia and is theonly avian species that extracts seeds fror.i closed conesof casuanna trees, apparently its only food source Itpicks one cone at a time with its relatively enormous bill,transfers it to its foot, and places it against the verybroad "cutting edge" of its mandible. The extremelyshort maxilla with its smooth inner surface bites off thedistal end of the cone and rakes the exposed seeds intothe mouth where they arc collected under the tongue.The upper bill tip is then used as the instrumental part ofthe jaw against the transversal step on the inside of themandible to split open the coals of the seeds that arcretrieved one by one with the tongue. This use of thebill is exactly opposite to that in all other seed-shellingparrots, which use the cutting edge of the mandible towork against the transversal step on the maxilla Clalliami probably represents a side branch of the cacaluidstem and evolved from an ancestor, with a pmccr-hke bil!that was devoid of internal structures foi seed-shellingand in which both mandibles were equally instrumental.Such a bill is still found in Cnlvnlorlivnchus banksiigrantoiivnc. another red-tailed Black-Cockatoo

FUNCTIONAL ANATOMY OF THE CONSTRICTOR-DERMOTEMPORALIS MUSCULAR COMPLEX INTHE DOMESTIC TURKEY, MELEAGRISGALLOPAVO. AND ITS RELATIONSHIPS TO THESUPERFICIAL FASCIA AND FEATHER TRACTS.K.N. dc Silva* and D.G. Homberger. Louisiana StaleUniv., Baton Rouge.

Basically, the neck of birds is composed of fourclosely associated tubular structures, i.e., the centralskeletomuscular vertebral column, the trachea and theesophagus on the ventral to right side of the neck, andthe surrounding outermost tube consisting of the skin, thesuperficial fascia (F. supf), the M. constrictor colliccrvicalis (M ccc), and the M. dcrmotemporalis (M. dl).The cranial and caudal borders of the slcevc-likc M cccwith iis circular muscle fibers arc anchored by fasciae lothe crania] and thoracic portions of the F. supf TheM.ccc is aponeurouc where it underlies the thickenedpans of the F. supf, which are interlarded with fat and,in turn, underlie the caudal parts of the doisal and ventralcervical feather tracts that contain large feathers. Somemuscle fiber bundles of the M.ccc attach directly to largefeathers of the ventral cervical tract. The longitudinal M.dt originates from the tempoial region of the skull andserves as antagonist to the M.ccc, which it underliesThe complex structure of the outer tube of the avian neckis necessary to jllow and facilitate the movements of theskin, feathers, and cervical organs individually andrelative lo one another, as the neck of birds comprisesmore cervical vertebrae and is more flexible than that ofmammals.

ABSTRACTS 59A

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Zebra Mussels

290 291

MECHANISMS MEDIATING OOCYTE MATURA-TION AND FERTILIZATION IN ZEBRA MUSSELS.K. Kyozuka, P.P. Fong,* and J.L. Ram, Wayne StaleUniv., Detroit, MI.

Zebra mussels can be induced to spawn with serotonin[5-HT]). are small enough (mature at 1 cm length) toapply chemicals efficiently to whole animals, and haveoocytes with clear cytoplasm, making them an excellentmodel system Tor studying oocyte maturation mechan-isms. Prior to spawning, oocytes are at prophase I(germinal vesicle [GV] intact), and 5-HT causesprogression to metaphase 11 followed by spawningFertilization triggers polar body extrusion [PBE| andcleavage. The goal of the present experiments was todetermine the roles of cyclic AMP, Ca~+, pH, and Na +

in oocyte maturation and PBE. Dissection of oocytesinto zebra mussel ringer always elicits GV breakdown(GVBD). Treatment of ovarian fragments with .5 niMiheophylline and .05 mM forskohn enables approx. 30%GV intact oocytes to be isolated, suggesting an inhibitoryroleforcAMP. Treatment of whole animal with lOmMA23187 (Ca2+ ionophore) triggers GVBD withoutinducing spawning, suggesting an activational role forCa2 + . After 5-HT-mduced spawning, PBE wasactivated by fertilization. PBE could be triggered by 10mM A23187, a response that takes place even in Ca2 + -free ai lificial fresh watci (AFW). PBE was blocked bylow pH (6.0). PBE was not affected by aimlonde oiNa+-free AFW. These data indicate PBE may betriggeied by release of intracellular Ca~T and regulatedby pll, however. Na '"-II'1" exchange piohably docs nothave a role in these mechanisms.

DISPERSAL OF THE ZEBRA MUSSELDRE1SSENA POLYMORPHA: NATURAL VS.HUMAN-MEDIATED MECHANISMS.Johnson, L. E. and J. T Carlton. Univ. ofCalifornia, Santa Barbara and Williams College-Mystic Seaport, Mystic CT

Overland dispersal is the means by which thelarge scale geographic spread oflhc zebra musselwill continue. Both natural (waterfowl) andhuman-mediated (rectealional boating) vectors arcsuspected of rapidly dispersing /.cbra musselsoverland. Observations indicate lhat boih larva!and adult zebra mussels are frequently transportedby movements of recreational boats betweenbodies of water. Surprisingly, the adult musselswere rarely found attached to the exterior of boutsurfaces and were instead frequently transportedon aquatic vegetation entangled on boat trailers.Small-scale experiments demonstrated that duckscan also transport larval and adult mussels.However, the low numbers (< I mussel/duck/tnp)transported under llie favorable conditions of theexperiments (i c , short distances and high musseldensities) suggests that [his natural vector ofdispersal is of far less importance than humanactivities in furthering the spread of this exoticspecies.

292 293

DIETARY EXPOSURE TO ORGANICCONTAMINANTS OF WATERFOWLTHAT CONSUME ZEBRA MUSSELS.EJ. Mazak* and H.j. Maclsaac. Univ. ofWindsor, Ontario.

Waterfowl were collected from theDetroit River and western Lake Erie fordiet and organic contaminant analysis.Zebra mussels bioaccumulatc conl.im-inants and are a primary food source for avariety of diving ducks (lesser and greaterscaup, common goldeneye). Other species(mallard, canvasback, redhead) containedmainly macrophytcs, snails or grain.Waterfowl wing and liver tissues wereanalyzed by gas chromatography fororganic pesticides and PCBs. Ducks thatconsumed zebro mussels had higherconcentrations of most contaminants thannon-mussel consumers. This pattern wasmost pronounced for high Kovv

compounds. Contaminant profiles ofducks that consumed or avoided musselsalso differed. Zebra mussels haveprofound effects or. ecosystems, possiblyincluding alteration of contaminant cyclin;

ZEBRA MUSSEL HABITAT EXPANSION BYSOFT SUBSTRATE MODIFICATIONP.A. Bcrkman, D.W Gaxlon and S J. Van Bloem.Ohio State Univ., Columbus and Indiana Univ ,Kokoino.

Populations of llie zebra mussel (Drcisscnnpolynmrpha) weic studied in western Lake Eric withsidescan sonar and remotely operated vehicles alongwith in s/iu collections lo assess their expansion intosoft substrate habitats. Because Drasscna hasbyssal threads fur attaching to hard substrates, softsubstrates have not been considered to be suitablehabitats. However, tins study clearly demonstratesthat dense Drcisscna populations exist in anextensive mosaic on sand and sill substrales.Microscopic examination of Vrci'ssc/m assemblageson Ihcsc soft substrates revealed lhat recentlymetamorphosed mussels can propagate their byssalthreads over individual grains smaller than 1.0 nun.These byssal threads then proliferate, creating aconglomerate of sand grains for subsequent musselcolonization. This /.ebra mussel recruitmentmechanism m soft substrate areas reflects theiradaptive capacity to spread into novel habitats.Consequently, models which forecast the ecologicalimpacts of this s,%x-.cs niusl uiuuilc Ihcr populationdynnmiL-s in both hard and soft substrates

Ti..s research V.JS sapporlui b> CW.o S i Grur.;

60A AMERICAN SOCIETY OP ZOOLOGISTS

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294 295ZEBRA MUSSEL GROWTH ALONG ATEMPERATURE AND NUTRIENTGRADIENT.C.E. Kraft* and D.K. Padilla. Univ.Wisconsin-Green Bay and Univ. Wisconsin-Madison.

Field experiments conducted in 1993 and 1994 showedlarge differences in zebra mussel (Dreissena polymorpha)growth along a gradient of temperature and foodavailability in Green Bay, Lake Michigan. Mussels wereplaced in cages after being individually lagged, weighednon-destructively, and measured using a video imagingsystem. Reproductive condition and weights (destructive)were taken upon retrieval. During a 4 1/2 month periodmussels grew larger at warmer cutrophic sites than atcooler mesotrophic sites. However, differenl environmentalconditions produced different seasonal patterns ofgrowth We found significant linear correlations betweennon-destructive indirect estimates of body mass and directestimates of body mass. Shell length was not correlatedwith dry body mass at most sites, with the exccpiion of onelocation Reproductive condition can explain much ofthis variability.

EFFECTS OF GLOBAL CHANGE ON ZEBRAMUSSEL SURVIVAL.B.L.Bukaveckas, J.H. Thorp, and J.E.Alexander,Jr.* Univ. of Louisville, KY.

We examined the impact of elevated watertemperatures and turbidities on the survival ofzebra mussels (Dreissana polymorpha) and quaggamussels (D. bugeiisis). Mussels from Lake Erie(both species), and zebra mussels from threerivers: the Mississippi, Ohio, and Hudson Rivers,were placed in 24 tanks (2100 L) after labacclimation to 22C for > 2 weeks. Tanks weredivided into three temperature treatments:ambient, elevated 2C, and elevated 4C aboveambient by heaters. Half of the tanks were atambient turbidity, and half were elevated 2X withbentonite clay. We followed survival from Julythrough October 1994. Zebra mussels from theOhio River had the highest survival, followed byLake Erie zebra mussels. Quagga mussels hadhigh survival at ambient temperatures. Survival ofthe Hudson River and Mississippi River zebramussels was lower.

ABSTRACTS 61A

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Animal Behavior

296 297ACTIVITY LEVELS OF DOMINANT

AND SUBORDINATE LIZARDS,ANOL1S CAROLINENSIS

JM Harris and N. GrcenbergDepartment of Zoology

University of Tennessee, Knoxville

Seven pairs of animals were placed in arrays ofthree interconnected cages through which theywere permitted unlimited movement throughsmall doorways, but were unable to view eachother when in separate cages. Each pairestablished dominance relationships. Movementsof each member of a pair between cages andactivity levels when animals were eithertogether or in separate compartments werecontrasted with each individual's activitypatterns when isolated. Both dominants andsubordinates were found to be less active in thepresence of the oilier animal than when alone.In addition dominant animals had depressedactivity levels either alone or with thesubordinate, while subordinate's activity levelstended to be higher than their baseline levelswhen they were apart from the dominant. Also,dominants had the highest and subordinates thelowest movement rates between cages.

OVARY DEVELOPMENT IS CORRELATEDWITH DOMINANCE STATUS AMONGQUEENS IN A CYCLICALLYPOLYGYNOUS NEOTROPICAL BUMBLEBEE.M.C. Jost* and S.A. Cameron. Univ. ofMassachusetts, Amherst and Univ. of Arkansas,Faycttcvillc.

Polygynous colonies (those with multipleegg-layers in the same nest) are commonamong the ants and wasps but are uncommon inbees. In the present study we examinepolygyny in a Neotropical bumble bee, Bombusatrauis. Polygyny has never been observed inany other species of bumble bee. We confirm aprevious observation of polygyny in thisspecies and document the formation of adominance hierarchy among multiple queensduring a temporary polygynous phase. Thephysiological components of dominancebehavior in B. alraius were not known.Dominance interactions among individuallymarked queens in a field-collected colony wereobserved for four weeks in the laboratory. Sizeand ovarian development were determined foreach queen. Dominance is positively correlatedwith insemination and ovary development andis not correlated with overall body size. It isprobable that 3. at rams exhibits intraspccillcvariation in cyclical polygyny across itsgeographic range.

298 299IF DARWIN HAD DONE A U'lTLJEMATH -- NEW GRAPHS OF DATA INBEHAVIOR AND ECOLOGY.E.R. Meyer. Loyola College of Maryland.

A common problem in ecology and behavioris that several kinds of data reflect a similarpopulation, and bear on the same idea, but it isdifficult to compare different kinds of data tosee how they test that idea. Darwin resolvedthis problem by testing ideas with data fromdifferent sources, in sequence. Sequentialtesting can be more informative than lookingfor correlations. It leads to testing alternatehypotheses, described as strong inference byPiatt (1964) for molecular biology, andextended to animal biology by Wenner (AmerZool, 1989). The next problem is how to bringthe resulting variety of data into a graph.

New graphs are shown here that do bringtogether data from different sources that are allrelevant to the same idea. The graphs caninclude criteria, and compare each datum withits criteria. They indicate the accuracy of thedata in each habitat and site. These graphsshow how evidence from different sourcesbears upon the same major questions.

A NOVEL FORM OF MATE-GUARDING/FEMALEDEFENSE POLYGYNY IN WESTERN DIAMONDBACKRATTLESNAKES.J.K. O'Leile, S.J. Beaupre and D. Duvall. ArizonaState University West, Phoenix.

Western diamondback rattlesnakes (Crotalusatrox) in upper Sonoran Desert communities ofcentral Arizona exhibit two periods ol mating.One occurs in the spring just after emergencefrom winter hibernation and the second later inthe summer, typically just after summer rains.In late summer, males and females are spatiallydispersed and rarely observed together. In thespring, conversely, males and females areclustered at dens, and conspecific interactions ofvarious sorts are observed commonly. A novelform of female mate-guarding by males has beenobserved at this time, one we refer to as"stacking," wherein males coil atop of andcompletely cover females lying immediatelybelow. Several males sometimes attempt to stackatop a female, and never have we observed stackscomprised only of males or only of females. Weinterpret these patterns in the context of theoryaddressing trade-offs in potential sexual selectionforces acting on mate searching versus handling.In our models handling can include male-male andmale-female interactions.


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Animal Behavior

300 301

THE 'COMPETITIVE EXCLUSION' MODELAND AMPHIPRION CLARKII : IS IT AFACTOR IN iMPRINTING ?B. Sailors' and N. Sanders. NortheastMissouri State Univ., Kirksville.

Imprinting and the 'competitive exclusion'model were examined using Amphiprionclarkii anemonefish and Heteractis maluanemones. Fourteen different anemones andten different anemonefish were used in thestudy. A single anemonefish was placed in aglass aquarium with first one anemone, thenseparately with a second anemone. Afteracclimating to both anemones separately, thefish was then placed in a tank with bothanemones and allowed to choose whichanemone to reacclimate to. The anemonfchosen by each anemonefish and trMreacclimation time were recorded. Sixanemonefish chose the second anemone overthe first anemone. Statistical analysis (t-test)showed that reacclimation times foranemonefish that chose the first anemonewere significantly shorter than for fish thatchose the second anemone. The resultsindicate that the 'competitive exclusion' modelmay be a factor for imprinting in anemonefishand anemones.

Tl IB USII O F VISUAI . L A N D M A R K S ASTUKKITORIAL HOI INIJAKIIuS BY Tl li:CICADA KILLliK WASP.K.G. Trinca* and P.K. Easoii. NortheastLouisiana Univ., tvlonroc.

Male cicada Killer wasps (Sphrcnisspceit'siis) defended mating icrniorics olapproximately I m - on a grassy lawn ilial VULSwithout vi.sual landmarks On ! I August1994, the icni loncs were mapped using j>ndmaikcis placed >il ! m in tcnals . Then, 30wooden dowels, which measured 90 cm inlength and 1 cm in diameter, were laid on theground to pun ide visual landmarks. The)were placed so that no dowel paralleled orcoincided with a territorial boundary, asid sothai each dowel was at least I m from otherdowels. On 12 August , wasps ' terr i torieswere remapped; the new maps revealed thatthe wasps had modilicd their icrniorics so thatthe dowels defined the boundaries. Of the 2 9dowels that were in del ended areas, 28 wereused as boundaries ( d = 33.54, df = I, p <(l.(X)l, using the conservative assumption Ihaldowels had a 0.5 probability ol being used asa boundary)- Those results suggest thatlandmaiks may improve dcfcnsibihty byincreasing ihc stability of bounda: ics.

302 303PRECHOICE EFFECTS ON FORAGING CHOICE.Williams, \V. A. University of California, San DiegoDelay-rcduciion theory has served as a reliable predictor ofchoice in a variety of foraging simulations. Opcrantanalogues of foraging usually focus on independentperiods of searching, handling and consumption. However,bouls of foraging may be intcrspcrcd with non-foragingbehaviors. These prcchoicc periods may alter theinterrcinforccmcnt interval such thai questions ariseregarding 1) ihc definition of ihc foraging context, 2) ihcformulation of the delay-reduction and optimal foragingmodels, and 3) ihc effect of prcchoicc periods onsubsequent choice. In Experiment 1, a fixcd-inicrval 200-sprcclioicc period was presented prior to the initial-links ofa standard concurrent chain; rcinforccr magnitudes wereequal but handling delays were not. In Experiment 2,subjects' chose between outcomes which differed in boihamount and delay. And in Experiment 3, subjects faced achoice between a smaller, more immediate single reward,and a clustered encounter consisting of two larger, moredelayed prey items. Choice proportions did not vary as afunction of prcchoicc duration, although choice did appearto respond to simitar increases in delay when incorporatedinto ihc search phase. Results suggest that prcchoiccevents liave no direct effect on the subsequent choice, andthat the traditional, molecular view of optimal foragingtheory provided an sufficiently accurate description of theforaging context. The results also indicate that the abilityof a stimulus to serve as an effective conditioned rcinforccris best determined by comparing ihc reduction in time toprimary reinforcement stignaUcd by that stimulus, relativeto the onset of ihc preceding stimulus, not relative to Ihcaverage intcrrcinforccmcnt interval.

COORDINATE GROUP AMBUSH: AZTECA ANTSEVALUATE PREY ABUNDANCE.H. C. Morais. Dopt. do Ecologia,Universjdade ce Brasilia70910-900 Brasilia,DF, Brasil

When +i-.n mean potential prey abundancei s 3.1 insects/10 min (Nov-wet season),Azteca sp uses heavily the slt-and-waitgroup behavior and 27% of the nest plantleaves are occupied by ants. For a rateof 0.3 insects/10 min this behavior i sfour times less frequent and, when thepotential prey abundance drops to 0.08insects/10 min (May-dry season),evaluation groups of 3-5 workers stay onthe leaves but they are not successful incapturing mobile preys. Experimentalmanipulation of prey availabil i ty showsthat the increase in prey abundance i sthe tr iger for the a-nbush groupsformation.

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Developmental and Cell Biology

304 305THE EFFECTS OF FEEDING ON TJiE DEVELOP-MENT OF THE CRAB, HEHIGRAPSUSOREGONENSIS.M.E. Bryant* and S.D. Sulkin and G.McKeen. Kortheast MO. State Univ.,Kirksville and Western Washington Univ.,Bellingham.

Effects of feeding on developnent oflarvae of the crab Hcnip.rapsus oregon-ensis were determined by exposingthem to prey for limited periods of timethroughout development1. Percent sur-vival through stage 4, mean day cf molt,percent mortality per stage, and stageduration were calculated for all treat-ments. Larvae fed for one hour per dayshowed lower survival through stage 4than those fed for eight hours ortwenty-four hours per day, with diff-erences seen between the latter twotreatments. Increased nortality inthe one-hour treatment occured onlyduring zoeal stage 1. Time of exposuresto prey and instar duration are indir-ectly related, with delay in moltingseen more significantly in the one-hourtreatment than in either the eight-houror twenty-four hour treatments.

THE EARLIEST CHANGES IN GENE EXPRESSIONINDUCED BY THYROID HORMONE IN THEDEVELOPING AMPHIBIAN HYPOTHALAMUS.Robert J Denver'1, Yun-Bo Shi2 and Su.shama Pavgi'. 'TheUniversity of Michigan, Ann Arbor and ~NICHD, N.uionalInstitutes of Health, Bethcsda, MD.

Thyroid hormone (TH) is the primary morphogen respon-sible for inducing amphibian metamorphosis The hypolha-lamus controls the activity of the thyroid axis and the differ-entiation of hypothalamic neurons is controlled by TH. Inorder to understand the molecular mechanisms involved inneural differentiation, we have cloned a scries of genes thatarc rcguiaicd by TH in the tadpole'hypothalamus using PCR-bascd subtractivc hybridization. Subtractivc libraries wcicprepared from hypothalamic tissue collected from Xcnopuslarvae cither treated with 5 nM T in the water for 24 hoursor untreated. As many as 40 cDN'As corresponding to genesthat arc rcgulateJ by TH were isolated. Approximately halfof these genes ate up- and Lilf arc down-rcgnialcd by TH.Several of the genes isolated by this procedure have beenidentified. The most abundant upregulatcd cDNA speciescorresponds to a protein which has sequence homology to thezinc finger region of human Spl. Other upregulatcd genesisolated include a basic leucinc zipper (homologous to bZIPregion of human E4BP4) and the thyroid hormone receptor 15proteins. Interestingly, we isolated cDNA for the corticolro-pin-reieasing hormone (CRH) gene, which functions as ancurocndocrinc regulator of the thyioid axis during meta-morphosis; this gene is strongly downregulatcd by TH.Sequencing of the other clones isolated should provide fur-ther information on the spectrum of genes that arc regulatedby TH in the developing amphibian hypothalamus. (Support-ed by NSP grant IBN-9219211).

306 307FACTORS AFFECTING CA"MICUOINJECTIONINDUCED CLEAVAGE IN OOCYTES OF THE FROGRaiia pipiensJ M. Freeman* and C.A. Lcssman , University of Memphis,TN

During mciotie maturation the amphibian oocytc cortexdevelops a calcium sensitive contractile mechanism Thismechanism w.is studied b> utih/.ing an ass.iv that measures (hecompetency ormnlunng ooeytes to undergo a cleavage- l\pecontraction in response to Ca"microinjcction. Studies of R.pipiens oocytcs were carried out 1) to identify the time ot thefirst appearance of this Ca"micioinjcction-induccd cleavagecompetency (Ca"MIC) during piogcslcionc- inducedmaturation and 2) to determine if the phorbol ester, phuibol12-myristale 13-acctate (I'MA, a I'KC activator) could induceCa*'MlC competency. Ca"MIC competency occurred a'17.7hr (n=4 fiogs) into the tune course of progesterone-induced maturation. Progesterone- induced Ca"MlCcompetency usually occurred after germinal vesicle dissolution(GVD), the latter occurred at I4.8hr into progesterone-induced maturation. In contrast, PMA was found to be a potentinduccr of Ca**MIC competency after a few hr of incubation,while GVD was not obsencd. H7. a PKC inhibitor, was shownto partially inhibit progesterone- induced GVD and Cu"MICcompetency Further work with cytoskelctal inhibitors andcyclohcximide indicated that progesterone- induced GVD andCa"MIC competency are prutcin synthesis and intermediatefilament dependent while PMA-mduccd Cn'\MIC is nut. Thesistudies provide inituil e\ uleiiLC loi .1 link between I'KC .IIHn ; . i l u r . i t . n n . i l u i . . n ^ e s ;n li-e li / . . , ' . . >•* r, : ^ \ , L SL.J ;;. ,,L.ii li_.

M i l \irj:v. I I I ) -2 f i ' J t J !

RETROVIRUS-MEDIATED TRANSFER ANDEXPRESSION OF TRANSGENES IN MEDAKA J KLu>, J.C. Burns2, and Thomas T Chen''University of Maryland Center ofManncBiotechnology, Baltimore, MD 21202,2Dcpanmcm ofPediatrics, School of Medicine U.C. San Diego, La Jolla.CA 92093We recently developed a unique method of introducing

transgencs into medaka embryos by a pseudotypedpantropic viral vector. This pantropic \cctor contains theLTR of Moloncy murinc leukemia virus (Mo-MLV), theG glycoprolcin of VSV-G and a reporter gene (nco orhe'/.) regulated by the LTR ofRSV. Newly fcrtili/.cdmedaka eggs (dechorionated or non-dcchorionalcd) wcicclcctroporatcd at different voltage settings in a Backonclcctroporalor with 4xlO4 cfu/ml of the pseudotypedpantropic virus The survival rates of the clcclroporatcdembryos arc in the range of 05% to 20% with increasingvoltage in clcctroporation. Dcchononalion docs noteffect the survival rates of embryos significantly. Theresults of PCR analysis show that up to 61% of the 1-2month-old fish carry the transgenc. The efficiency oftransgene transfer is greatly enhanced by dcchononalionFurthermore, incubation of dcchorionalcd cnibnos withpanlropic \cclors o\crmghl without clectroporation alsoresult in 60% of successful rale of gene transfer withoutcompromising ihe survival rate of embryos. Expressionsof transgencs in both P, and F, transgenic individualsarc also observed


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ROLE OF HYALURON1C ACID IN THEEMIGRATION OF QUAIL NEURAL CREST CELLS.L. Luckcnbill-Edds*, C. Lcuthacuser, J. Hcllmund. OhioUniversity, Alhcns.

Hyaluronic acid (HA), a component of the extracellularmatrix in the early avian embryo, influences the number ofneural crest cells that emerge from the neural tube inculture. To learn whether the target of HA on neuralcrest cell emigration is neural crest cell proliferation, wecultured two-day neural tubes for 20-22 h in HA or CONmedia in the presence of 5-bromo-2-dcoxyuridinc (BrdU),an analog of thymidinc. BrdU-labcled nuclei, detectedwith the indirect lmmunofluorescent technique, werecounted to determine the proportion of labeled cells in theHA and CON cultures. No significant differences werefound in number of BrdU-labclcd neural crest ceilsbetween HA and CON treatments, implying that othermechanisms arc the target of HA influence.

RETINAL DEVELOPMENT IN THE BRAZILIANOPOSSUM (MONODELPHIS DOMESTICA).K.M. Lyser,' M.H. Grayson and K. Wono. HunterCollege ol the City Univ , New York, N.Y.

To provide a basis for studying the origin of spocilicneuronal types, we have examined the pattern ofdifferentiation beginning at birth. The neonatal neuralretina consisteo mainly of neural epithelial (ventricular)coils; a few differentiating ganglion cells were presentnear the inner edge. By 3 days a distinct ganglioncell layer, 3-4 nuclei deep, was present in the centralretina In the per.pheral retina there wore ventricularcolls with a thin marginal zone, indicating a pro-gression from center to periphery which lastod untilthe time of eye opening. The inner plexiform layer(IPL) was visible by 10 days in the central retina andsome amacrme cells were present at the inner edgeof the neuroblastic layer. During the next two weeks,arnaenne cells increased and the IPL became wider;the outer plexi'orm layer (OPL) appeared sclerad to afew presumed horizontal cells which could be seenamong the neuroblastic cells At 28 days (just beforeeye-opening) all layers were clearly identifiable in thecentral retina; photorecoptors were beginning to formouter and inner segments In the peripheral retina theOPL was not yet apparent At 34 days, just alter theeyes opened, all layers were present throughout theretina. Retinal development in Monodelpt'is is similarto that of other mammals It lasts for a fairly extendedperiod, mostly postnatal, an advantage lor studiesusing a small, easily maintained laboratory mammal.(Supported by 3 PSC-CUNY Research Award.)

310 311

THE SUBSTRATE ATTACHMENT OKAMPHIMIAN CELL LINE ATCC CCL-128 ANDIMMUNOCYTOCWEMICAL ANALYSIS OFMICROTUI5ULE COLIKSTAHILITYR. McDonald*. R.I I. Reig. and C.A l.cssinan. TheUniversity of Memphis, TN

Subslr.ile attachment ol the leopard frog liana pi/iicmcell line ATCC CCL-128 was examined. Ceils weregrown with no scrum, 5% or 10% scrum; attachmentdiffered significantly with no serum vs other treatments.Preliminary data indicate a significant increase inattachment with IGP-I and Insulin, 0.01 ng/inl and O 01(.tg/nil respectively. Attachment is affected by thestability of the cytoplasmic miciotiibulc complexCCL-128 cells were incubated at 20'C then .subjected to5 3"C for 3 hrs or 24 lirs. Attachment decreased as thetime at 20"C decreased. Dot blots of cell fractions from0°C,5.3"C and 20nC indicate pellatablc tubulin present atall temperatures. Cells incubated at either VC or 20"Cfor 3 hrs, were stained with anil tubulin antibodies,DM IA or 6-113-1. Cells at 0°C had DM IA and6-1IB-1 stained microtubules, although degree ofpolymerization varied. Therefore, liic CCL-128 cell lineexhibits cold- stable imcrolubulcs which do notdepolymcri7x when subjected to OX. These d.ita suggestCCL-128 cells have factors which prevent coldtemperature dcpolymeriiation of microtubules.Supported by NIH grant I1D-26901.

LIGHT, FLUORESCENCE AND LASER CONFOCALMICROSCOPICANALYSISOFFERTILIZATIONANDPOLYSPERM Y IN SEROTONIN SPAWNED EGGS OFDREISSENA POLYMORP1IAM. Misamcirc*, T.I I. Diet/, II. Silvcrman, and J.W. Lynn.Louisiana Slate Univ., Baton Rouge.

Eggs from isolated animals spawned with 10'3 Mserotonin were inseminated with sperm concentrationsranging from 103 to 106 sperm/ml. Even at lowconcentrations, multiple sperm attached to the egg surfaceand sperm head incorporation occurred within 3 min. Thesperm tail remained partially outside the egg andmotionless. Incorporation was complete at ~5 min postbinding. In the egg cortex, the sperm head rotated 1800.1

At 5-6 min, quivering of the sperm head in the egg cortexconcomitant with erratic flagellar movement was followedby a rapid translocalion of the sperm head towards the egginterior. Sperm nuclear decondensation did not occur untilafter this initial translocation. Sperm pronuclcus formedas small vesicles (7 (im) at 9-10 min and briefly disappear.The male pronuclcus reappeared at - 2 1 min enlarging insize over the next 10 min before fusing with the femalepronucleus. Cleavage occurred by 60 min postinsemination. Vesicles were verified as proni'dci withDNA specific stains (Hocscht 33342, 7-aminoactinomycinD) on cpiftuorcsccnl or laser confocal microscopes. Forsperm concentrations of ilO4 sperm/ml, frequency ofpolyspermy ranged from 26-76% (for eggs with greaterthan 2 pronucici). Male pronuclci could exceed 14/cgg.These observations suggest that a specific sequence offertilization events may occur, but blocks to polyspc my areineffective in a significant proportion of serotonin spawnedeggs. Sea Grant # R/ZM-1-PD.

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312 313HEAT SHOCK PROTEIN EXPRESSION DURINGTEMPERATURE-DEPENDENT SEX DETERMINATIONIN THE TURTLE TRACHKMYS SCRIPTAC.R. Paulson* and S.C. Smithgall. LakeForest College, Lake Forest, TL.

In the red-eared slider turtle,Trachemys scripta, sex is determined byenvironmental temperature duringembryonic development. We have studiedchange in embryonic proteins during thecritical period Cor sex determinationSDS-polyacrylamide gel electrophoresisand western blotting. To analyzesynthesis of proteins, radiolabeledmethionine is injected into eggs andthe results are measured by scintillationcounting or autoradiography of gels.Kestern blotting showed that Heat ShockProtein 70 is present in embryos at allstages of the critical period for sexdetermination in eggs incubated at eithermale- or female-producing temperatures.Embryos subjected to heat shock at 33°Cshowed repression of total proteinsynthesis, whereas those shocked at 35 °or 37° C did not.

CHANGES IN CRAYFISH m R N A EXPRESSIONDURING M O T O R NEURON ADAPTATION.R. Pekhletsky1*, R. L. Cooper, C. Hampson' andH. L. Atwood. Dept. of Physio1, and Faculty ofPharmacy', Univ. of Toronto.

The purpose of this stud>' is to determine whichproteins are responsible fcr the physiological andmorphological conversions observed when a phasicmotor neuron is transformed into a tonic-like motorneuron as a result of heightened electrical activity.Using single identifiable neurons, we aim to determineif: (1) mRNAs are up or down rugulated intranscription; and 12) to identify the proteins whichore changing in their level of transcription and whichare responsible for the conversion of neuronal celltype. In the somala (dia 80-120 um) of singleuniquely identifiable crayfish unco.-.ditioned andconditio" .*i phasic motor neurons, isolation of thecytoplasm was performed with forge dometer ( — 10 to20 um) suction patch electrodes We have amplifiedthe rr.RNA, contained in the cytoplasm, using twoapproaches. One was to make aiT.|_ iifled antisenseRNA, while the second was to make use of ligation-mediated single-sided PCR methodology. Screeningto measure the differences of the resultant dot blotsto known cDNAs is in progress. This will allow us todetect whether changes in specific mRNA(s)expression have occured in transformed phasic motorneurons. Sequencing of the amplified signals thatshow altered expression profiles, will contirm theidentity of the proteins.

314 315SEQUENCE ANALYSIS AND RNA EXPRESSION OF ADROSOPHILA cDNA ENCODING A PROTKIN WITHH0M0L0GY TO INSECT VENOM PEPTIDES.M.C. Schreiber* and G.E. Kovalick.Miami University, Oxford, OH.

Using PCR, we have isolated an 890 bpcDNA fragment from total RNA of adultDroKophiln. This cDNA f rafiir.cn t hybridizespreferentially to an R.NA present in embry-onic hemocytes. The cDN'A fragment hasbeen cloned and scquenced and has beenfound to contain an ORF encoding a puta-tive protein at least 265 anino acids inlength. Analysis of both the nucleotideand amino acid sequences revealed that thecDNA has '•.?~ology to antigen 5, a majorcomponent of wasp venom, and to a patho-genesis-related protein of tobacco. Wehave determined that the cDNA hybridizesto a single 1 kb transcript in the adult.Ke will present the complete codingsequence contained within the cDNA fromthis transcript. Ke will also presentdata from in situ hybridizations on thetissue specificity of the transcript.The sequence data and hybridization pat-tern suggest that the transcript encodesn protein with .1 role in the ir.:-uncresponse of Drosop'.iii.*?.

DETECTION OF VITELLIN-IMMUNOREACT1VEPROTEINS IN THE HL'MOLYMPH AND TISSUES OFTHE BLUE CRAB. CALUSECTES S.-WIDUSH R Un-.phrcj*. C.-Y. Lcc, and R.D. Watson University ofAlabama at Birmingham.

Previous sludics of fcm.ilc blue crabs have demonstratedthai the ovary (but not the licpalopancrcas) S) ntlicsi/csvitcllin (Vn) in viiro. To fuillicr test Ihc hypothesis ofcMia-ovanan synthesis of Vn, immunocyiochcmislry and EL1SAwere performed en hcmoi\ inph and tissues of crabs invarious stages of ovarian dc\clopmcnt. Crabs v.crc stagedaccording lo ooewe diameter. Immunocytochcnncal studiesshowed that Vn-immunoicactivc prolcins were absent inovarian tissues at stages I (oocyic diameter: 16-25 um). andII (30-60 |im). and were present at stages III (65-100 |im).IV (100-160 |im), and V (170-MO um): the hepatopancrcasand muscle were not iminunoreaclivc at any stage. ELISArevealed no Vn-iuimunorcaclivc proteins in hcmohmpli ofcrabs from stages I and II. Vn-immunorcaclivc prolcinswere detectable in some animals of stages III. IV. and V.Tiie average concentration of Vn-inimunorcacli\c proteinsfor these stages was 0.02 ± 0.01, 0.0210 04. and 0 12 ±0.15 mg/ml. respectively, the percentages of crabs uitlidetectable hcinolyinph Vn-immunorcactivity were 16.67(slagc III). 31 58 (stage IV), and 66.66 (stage V). Theresults arc not consistent witli the hypothesis that Vn-imniunorracti\ c proteins arc synthesized cstraovanally,released into Ihc hemoh m;)h. and subsequently sequesteredby \ itcllogcnic oocytcs. These data and prc\ ious in vitroexperiments suggest thr.l Vn is synthesized c\clusi\ch inthe ovary in the blue crab (Supported b\ MS-AL Sea Gir.nlNAKiRCO'55-.-.i;


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TUBUL1N HETEROGENEITY IN BRAINS ANDOOCYTES OF SOUTHERN AND NORTHERNFROGS OF THE GENUS Rnna.T. Wang* and C.A. Lessman. The University ofMemphis, TN

By using SDS-PAGE, 2-D gel elcctrophorcsis andWestern Blots, polymorphic luhulins wcic compaied inbrains and oocylcs of Rana pipiens and Ranaberlandieri At 0 °C, more soluble tubulins could beextracted from cither brain or oocjtcs in southern frogsvs northern frog indicating the presence of cold-stablemicFotubulcs in northern frog cells. At 20 °C. however,oocytcs contain relatively more soluble tubulins thanbrain in both species . Soluble tubulins (I6,000xg) wcicfound to consist of an oligomeric pool (molecular mass- 2,000 KD) and a dimeric pool in oocytes uponfractioiulion with Supcrosc-6b gel filtration Isolypietubulins differing between oligomeric and dimerictubulins were shown in 2-D clcctrophorcsis andimmunoblot probed with anti-lubuiin antibodies DM IAand DM IB. The preliminary data showed that averagetotal tubulin in each northern frog oocyle was O.fiOugbovine brain lubulin .ijinvalcnl (ranging from 0.05 to2.6Sug) as detected by Western blot and quantified withdensitomclry. These tubulin heterogeneities suggest thatlubulin isofonns may affect niierotubulc dynamicsrelated to specific functions of highly differentiatedcells such as those found in the brain and ovary.Supported by Ni l I grant IID-26901.

INTRAVESICL'LAR CLATHRIN, INTERMEDIATEFILAMENTS AND CALCIUM-BINDING PROTEINSFROM XICROSPORIDIAN SPORE WALLS.E. Weidner and S. Manaie. LouisianaState Univ., Baton Rouge

The saccular vesicles which arebound together on walls of Spraguealophii spores have clathrin, intermediatefilaments and calciun-binding proteins.By Western blot analysis, the clathrinlight chain cross-reacts with anantibody to 50 kDa polypeptide isolatedfrom plants. The intermediate filamentproteins cross-reaction to the K-4 andK-13 keratin antibodies. The clathrinpositioning within the vesicles is novelsince some electron microscopic evidenceindicates these molecules are positionedin linear rows within the vesicles. Thecalcium-binding protein appears to be acalmodulin analogue. A calcium influxis associated with the triggering of thesaccular vesicle dissociation whichcoincides with spore activation. Duringthis event, there is a phosphorylationof the intermediate filaments within thevesicular system.

ABSTRACTS 67A

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318 319AGE, GROWTH AND THE ANNUAL CYCLESOF LIPOGENESIS AND REPRODUCTION INACANT11URUS 1SA1IIANUS IN SOUTHERNFLORIDA.S. M. Wolfe1'. R.E. Ciahlrce2and R I- Spicier'.'Nova Southeastern University , OccanographicCenter, Dania, l-l "Florida Marine ResearchInstitute, St. Petersburg.

Ocean surgeon fish, Acaniluinis iuihiwuts. werecollected by hand spear (approximately 20/monlh)for one year from a shallow i= 6m) inshoie sue inSouthern Florida The fish were measured(standard length) and weighed, the gonads and I'albodies were removed and weighed and ololilhswere extracted. Gonadal-Soniatic Indicics (GS1)had a umntodal form with a sharp peak in January-March lor females and a broader peak, Decemberto Maich for males Fat body-Somatic lndicies(FliSI) peaked several months prior lo ihc peaks inGS1. Ololith rings were counted on the sagillacfrom 200 fish. Ring counts ranged from I lo 15. Afull determination of age and growth awaitsstatistical and chemical validation of these rings astrue annuli. Our results support the hypothesis of ,isingle, winter spawning period with gonadalrecrudescence aided by gonad associated falbodies.

HYPOXIA-LIMITIfD RESPIRATION, SURVIVAL,AND MATE-GUARDING BEHAVIOR IN ANAMPHIPODW.W. Hoback* and M.C. Barnhart. SouthwestMissouri Stale University, Springfield.

Fresh water gammaridian amphipods have beencharacterized as being intolerant of low oxygen.However, few studies have examined the effects ofhypoxia in controlled conditions. We tested survival inhypoxiu, oxygen-limitation of respiration, and effectsof hypoxia on male-guarding behavior in the amphipodGammunii iisciulolwiiiticus. Gender and age alfectsurvival of hypoxia. In a 48 hour exposure at I5C,LCW for juveniles was 8.0 Torr, for males 14.7 Torrand for females 29.4 Torr. Oxygen consumption ofindividual amphipods (Mo;> mg-g dry mass07Sh"') wasmeasured in relation to dissolved oxygen using Clarkoxygen electrodes in closed chambers (5 ml volume,stirred). KlO: was oxygen-dependent at ail levelsbelow air saturation. Temperature influenced the ralebut not the O, dependence. The relation betweenlogMOj and logPO- was linear, and regression yieldedthe following equations- At IOC. logMOj =(0.387logPO,)-LI7; at 15C: logMO:=(0.439 logPO,)-1.13,at 20C: logMO: = (0.408 !ogPO,)-0.915. Respirationof females was higher than that of males at IOC and15C, but did not differ at 20C. Mate guardingbehavior was inhibited by hypoxia. No pairingoccurred below 29 Torr and at 74 Torr over half ofseparated pairs failed to reform.

320 321

NATURAL HISTORY OF THE YELLOWSTINGRAY. UHOLOi'lU 'S JA.UAICKXSIS. IN-SOUTH FLORIDAJ.A * Siilikowski T P Quinn and R E SpielerNova Southeastern University. Dania Fl

During a 12 month period 108 stingrays werecollected from a 2700 x 200 meter area(approximately 5 rn in depth) Animals werehand netted, measured, tagged and releasedMales predominated the collection (62%) andranged in size from 159 to 36S mm total length(TL). Females (259 to 388 mm TL) were gravidyear round with parturition peaks apparently inAugust and December. There were norecaptures. In associated studies, stomachanalysis of 24 rays indicated a diet (by \oiumc)of' 33.7% polychaetes, 31 5% crustaceans,15.4% unidentified organic matter, 13 5%unidentified worms, 3 0% sipunculids, 2.2%nematodes and less than 1% inorganic matterVertebral centra rings from 20 rays (227 to 392mm TL, 12 femaies and 8 males) ranged innumber from 1-8 rings. However, further work>s needed to validate tlicse rings as true annuli.

THE PI1YLOGENY AND BIOGEOGRAPHYOF ARBOREAL EGG-LAYING FROGSW E Roberts. University of California.Berkeley.

I'hylogcr.eiic analysis mea l s that layingarboreal eggs on rocks or vegetation abovewaier, such that hatching tadpoles drop intowater, is a derived reproductive mode andevolved at least ten times in anurans In theAfrican family Hjpcroliidae, arboreal egg-layir.gis derived from terrestrial egg-laying, andreversal to aquatic egg-layhg occurred severaltimes within the largest ( > 120 species) genusIlyperohus. Terrestrial egg-laying lineages ofanurans are never derived clades withinarboreal eg;-!aying lineages, and thus arborealegg-laying is not a transition towardterrcstriality. Parental care, including nestbuilding and parental attendance, is stronglyassociated with all lineages of arborealegg-laying frogs. Arboreal egg-laying speciesusually oviposit in clutches, not singly. Whilethe origins of arboreal egg-laying are in tropicalrainforests, maintenance of this ira-.t occurs inxeric habitats worldwide and in temperate zonesof the Old World.


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322 323DISTRIBUTION, PREVALENCE. AND INTENSITYOF I'mlociilltplwm (DIPTERA.CALLIPHOR1DAE) INTHE NESTS OF COEXISTING BIRD SPECIESM.R. Rc\cls. Uim. of Arkansas, Fascllcwllc

Tin's sludy was conducted to assess patterns ofparasitism of I'rutocalhphora, a parasitic blowfly,within coexisting bird species Parasitic I'mloctilliplumilarvae residing in the nesting material completedc\clopmcnt by feeding on the blood of nidicolousyoung birds Frcc-lhing adult female blowflies selectwhich nests their eggs will be deposited in among thoseavailable in a gnen area, i was interested indetermining if host ncst selection is random or reflectsa preference for a particular host species, \cgetalionlaser, or ncst morphology. 302 nests of fifteen birdspecies were located, monitored, and collected in theO/.ark National Forest in northwestern Arkansas. USAbetween 1991 and 1993 The bird species wereprimarily open nesting neotropical migrjnls, althoughsome nonmigralory open and cavity ncslcrs were alsocollected Nests were searched for blowfly larvae orpupae, which were removed, allowed to emerge asadult flics, identified and counted Four new hostrecords for I'lvlocalbplwin aic reported here. AcadianFlycatcher (KmpiJunax vnvsccn.s). Black-and-WlntcWarbler (Mnioliha vaiio), Kentucky Warbler(Opomntis fomimus). and Hooded Warbler (11'il.mnuiairiiui) I'lolticaUifihaui parasitism patterns wcieinfluenced In host species, vegetation l a \u . .nu!temporal faclois

ABUNDANCE PATTERNS OFTUBULARIA-FEEDING NUDIBRANCHSAND PYCNOGONIDS, Eric C. Lovely (Intro,by L.G. Hams) Univ. of New Hampshire,Durham, NH. Population densities of Tubulariaand associated predators were monitoredduring the summers of 1993 and 1994. Weeklysamples were collected from an old float withan established fouling community and a newfloat that had no established fouling commu-nity at two sites on the new Hampshire coastTubularia spp. appeared earlier and persistedlonger on the old floats with an establishedfouling community than on the new floats. Amonoculture of Tubularia larynx developed onthe new floats. Pycnogonids were less abun-dant during the late summer on the old floatsthan on the new floats. This pattern parallelsplant herbivore associations where agriculturepolycultures have a lower abundance of preda-tors than in monocultures.

324 325POST SETTLEMENT SURVIVAL ANDRECRUITMENT OF PLEXAURIDGORGONIANS.H.R. Lasker. State University of New York atBuffalo.

The mortality that occurs shortly afterlarvae settle is an important variable affectingobserved recruitment rates among benthicinvertebrates. In order to assess post-settlementsurvival among Caribbean gorgonians 1 reared2000 planulae of Plexaura kuna and allowedthem to settle on 40 seasoned plcxiglas plateswhich were then returned to the reef. After 3weeks 253 planulae had settled and attached tothe plates. Mortality during the two weeksfollowing return to the reef was 60% and all 258of the recruits died within two months. Thesehigh mortality rates are consistent with low ratesof recruitment among most plcxaurids. 1 alsomeasured annual recruitment rates of three taxaat three sites in the San Bias Islands, Panamaover a 9 year period. Pscucloplexaura spp. hadthe highest recruitment rates at each site, andannual recruitment at one site averaged 0.10 m''.Plexaura homomalla annual recruitment was 0.01m'2. P. kuna recruits were not observed at twosites. Recruitment at the third site was 0.04 in'2.

VARIATION IN PARASITE POPULATIONAND COMMUNITY STRUCTURE OF TWOSYMPATRIC MINNOWS.L.J." Krebs and J. Janovy, Jr.Univ. of Kebraska, Lincoln.

Two species of minnows,Notropis dorsalis and N.stramineus, occur sympaCricallyin the Placte River of Kebraska.Although these fish schooltogether, segregation occursduring feeding. Both specieswere seined from the same localityat monthly intervals for twoyears, and the eyes, abdomenalcavity and gills were examinedfor parasites. Parasite com-munities were described quanti-tatively: infrapopulations ofparasites varied significantlybetween host and season. Larvaltrematodes were the best indi-cators of host niche separationon parasitism. In this system,parasite community structure isapparently more a function ofhost behavioral ecology than ofparasite specificity.

ABSTRACTS 69A

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326 327POPULATION DYNAMICS OK LARVAL ZEBRAMUSSELS IN SMALL AND LARGE LAKESS.A. Glover, M.F. Wofiord and D.W. Garton. IndianaUniv., Kokomo.

Phinktonic larvae of Dicixicna pulymurphu werecollected at frequent intervals during May-July from small(Lake Wawassee, IN, approx. 1200 ha) and large(western basin of Lake Erie) lakes. These two lakes alsodiffer in trophic status, with Lake Wawassee anoligotrophic system with a small drainage basin comparedto the eutrophic western basin of Lake Erie. Larvaldensity was calculated from quantitative .samples. Shelllength (N = 300) was measured using an ocularmicrometer. Spawning was highly synchionous in thesmaller lake and larval cohorts were well defined. Larvalgrowth was greater in the south basin of Lake Wawassee(3.1 /i/day) than in the north basin (I.S /i/day).Temporal variation of spawning events, combined wilhcomplex movement of water masses complicatedinterpretation of larva! size frequency distributions msamples from Lake Erie. However, three cohorts can bedistinguished over a period of 24 days. Estimates ofaverage shell growth rates approach 5 /i/day, greater thanthe estimated for Luke YVawassee, and implymetamorphosis may be acheived within thiee weeks.Development to metam.irphosi.s may require over fourweeks in Lake Wawassee. Thus, trophic status ofindividual iakes may influence duration of planklonicdevelopment of Drcis.\cnc.

Supported by Undergraduate Research Summer Institute,Indiana University Kokomo.

HOST ECOLOGICAL RANGE AND SYMBIONTDIVERSITY IN CORAL-ALGAL SYMBIOSES

Recent evidence shows that symbioiH laxonoimcand functional diversity in cnidanan-aigal syinbioscs isgreater than previously thought. Additionally, hosts appearto harbor one or two specific algal types. However, fewstudies have examined large populations of hosts across avariety of environmental gradients. If symbiotic algal typesare functionally variable, then algal diversity within a hostspecies may correlate with host habitat breadth. Hostswith larger habitat ranges will be more likely to containdifferent, 'habitat specific',symbionts. Preliminary studieswere conducted in the Florida Keys to determine thediversity of symbiontic algae (Symbiodinium spp.) found in6 species of rccf-building corals that differ in range ofhabitats occupied Mcntastraea cavemosa, Colpohyllianatans and Agancia agancitcs occupy habitats extendingfrom less than 1 mcier in depth to > 20 meters depth,while Favia fragum, Mycctophyllia aliciac, and Leptoseriscucullata have much narrower ecological distributions.Coral species were sampled from across their balhymetricrange and the genotypic composition of theirSymbiodinium spp. determined by restriction fragmentiength polymorphism (RFLP) analysis of PCR amplifiedsmall subunit nbosomal DNA (ssrDNA). M.cavcrnosa andC. natans contain a wider range of RFLP ssrDNAgenotypes than all other corals sampled, but the diversityof genotypes docs not appear correlated with location ofsampled colonies The relationship between syn'.biontdiversity and reproductive mode will also be brieflydiscussed.

328 329

THE EFFECT OF BLEACHING ON LIPID LEVELS INTHE CORAL MONTIPORA VERRUCOSA.

Corals host cndosynibiontic algae from which theyderive up to 90% or their fixed carbon in order to fulfilldaily metabolic requirements. Excess carbon is stored aslipid or excreted. Perturbations such as elevated scawatertemperatures and/or increase ultraviolet radiation causecorals to a lose their zooxanthellae and appear "bleached".This results in decreased carbon fixation due to thenear-absence of zooxanthellae and in turn may cause coralsto rely heavily on stored lipids. I hypothesize that as coralsbleach lipid levels decrease and the degree to which lipidlevels decrease is proportional to the length of thebleaching period. Bleaching was induced in the coralMontipora verrucosa by increasing the average totalirradiance via transplantation from lOmto lminKancohcBay, Hawaii. Three different groups of corals wereexposed for 4, 8 and 14 days respectively. Whilechlorophyll a levels decreased in each treatment, lipidlevels did not significantly change. Since coral metabolismdecreases during bleaching, it is possible that a 14 dayexposure is insufficient in order to observe a change inlipids. Additionally, any relationship between blenchingand lipid levels may have been obscured by low statisticalpower resulting from high within and among coralvariation lipid levels. Lastly, it is possible that corals cancompensate for decreased phoiosyntheticdly derivedcarbon uptake by substantially increasing heterotrophicfeeding. Aknowledgements: Research funded in part by&i Hawaii Ir.s:uii:c c.r Mar .is Bioiojr., :hc Pa:;::Foundauon anu tr.c Lr.:\ersuy ot Houston i,LGiA;. Dr.G. Wellington, Dr. P. Jokiel and Tom Wilcox providedf : d J : b

FACTORS AFFECTING PHEN0TYP1CPLASTICITY IN TAIL MORPHOLOGY OF PONDAND RIVER LARVAL PSEUDACRIS REG1L1A(PACIFIC TREEFROG)C.L. Bailey', S J. Kupfcrbcrg and M.S. Parker, Univ. ofCalifornia, Berkeley, and Southern Oregon State Umv ,Ashland.

Variation in tail morphology of larval P. regiliaoccurs between adjacent habitats along a northernCalifornia river. Pond larvae have large tails, with talldorsal and ventral fins, relative to river larvae Weconducted common garden and reciprocal transplantsbetween environments to determine whether variationwas associated with genetic differences, differentselection regimes, or developmental responses toenvironmental cues between environments, we conductedreciprocal transplant and common garden experimentsIn these trials, source effects were significant. Pond andriver tadpoles that were transplanted as eggs and raisedin flow-tl.rough enclosures, however, were more similarto each otl.cr than tadpoles unenclosed in their natalenvironments. We hypothesized that differences inprcdation pressure contributed to plasticity becausepredators were excluded from enclosures whereasambient predator density was significantly higher in thepond than the river. Both pond and nvcr tadpolesshowed morphological responses to odonatc predators ir,CNperiiTicntal tria:s. In addition, tirr.c to rr.-'tarr.crphcsisincreased and size at metamorphosis decreased.


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330

LARVAL RECRUITMENT IN THE FIELDEXAMINED WITH SETTLEMENTENCLOSURES.P. Baker* and R. Mann. Virginia Inst.Marine Sci., College of William & Mary,Gloucester Po.nt, VA.

The effect of an oyster reef foulingcommunity on settlement and survival ofoyster, Crassosirea viryiDica, larvae andjuveniles, was examined in the field.Larval enclosures were used to retainknown quantities of larvae over reef plotsand defaunated controls, during initialsettlement. The overall effect of the reefcommunity was strong, with significantlylower settlement and survival to 28 dayscompared to the defaunated controls.Within the reef treatment, however, thecorrelation of settlement with percentcover by the total fouling community, orby various fouling community species(including a sponge, a barnacle, and abryozoan) was poor. A probablemortality source in the reef was theabundance of very small predators, suchas 'uvcmle Matworms.

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331 332AN' INTEGRATED COURSE IN NEUROSCIENCEMETHODS FOR ADVANCED UNDERGRADUATESD.G. Blackburn*, P. Kchoe, J.E. Simmons, J.Bronzino, W. Mace, and S. Raskin. Trinity College,Hartford, CT.

The rapid growth of neuroscience as a multi-disciplinary field has created a need for coursesthat expose undergraduates to a broad array ofinvestigative techniques. We have developed anintensive, course for upper-level undergraduatesthat draws on diverse faculty interests. Asjuniors, students rotate through 4-5 facultyresearch laboratories during one semester, andgain experience with several of the followingapproaches: anatomy (e.g., histological techniques,cryotomy, and immunocytochemistry); neuro-psychophnrmncology (behavioral effects ofpsychoactive drugs before and after brain lesion-ing); electrophysiology (electrode construction,electrical recording and stimulation procedures,computer analysis of bioelectrical events, humanEEG and evoked potentials); receptor biology(radioligand binding assay, determination ofbinding parameters for neurotransmitterreceptors); neurochemistry (i.e., microdialysisandHPLC); human perception, and neuropsychology(cognitive testing). Because students completeinvestigative research projects in each rotation,they can determine in which laboratory to pursuetheir senior thesis research.

Anatomy and Physiology of a Model Motor System.B.R. Johnson* and R.I-I. Hoy. Cornell U.iiv., I'thaca

We arc developing a scries of undergi.uluaiclaboratoiy modules in ncuroliiology llial use thecrayfish as a model system. These modules empha-size quanuiaave methodology, principles of neuialfunction and physiological, morpnological andbchaviorial techniques in neuiobiology. In the twointegrated modules presented here, students examinethe motor control of a postural muscle m ihe crayfishabdomen. Fir.it, students examine mclhylene bluestained preparations to observe the anatomicalorganization of the ventral nerve cord and theinnervation of the superficial flexor (SR posiui.ilmuscle. This is followed by a simplified cobaltbackfilling and intensification procedine to visualizethe 6 motor neurons in the CN'S that innervate the SFmuscle. These travel in the purely motor newt: 3 thatleaves each abdominal ganglion. The second exer-cise uses extracellular recording to monitor sponta-neous ncuial activity in nerve 3. Students describeme patterns of activity and prcd.ct the ntimhci ofmotor axu.,s in ihe neive fioni the amplitudedifferences ol the action potentials. They examinemodulation of motor activity by stimulating sensoryfields that are either excitatoiy or inhibitory Com-bined morphological and physiological studies ofthis simple motor system facilitates undci standing ofgeneral principles of motor organization. Supportedby NSF gram 9051880, the Grass Foundation andthe Howaid Hushes Medical Institute.

333 334

COMPUTER SIMULATIONS AS A TEACHINGTOOL IN FRESHMAN SCIENCE COURSES -TWO EXAMPLES. Ryan, Wendy L. KutzlownUniversity of Pennsylvania.

The advent of personal computers has affectededucators in numerous ways, from wordprocessing class assignments and laboratoryexercises, to using spreadsheets for the analysis ofstudent laboratory data. Yet the desiie to providefreshman-level students with meaningful exposureto these electronic tools has often been frustratedby a lack of sophistication (on the part of thestudents), combined with a lack of relevantsoftware. Yet, there are suitable applicationpackages and one example is Stella, a systemsmodeling program. This modelling program hasbeen successfully incorporated into two freshman-level courses, Introduction to Oceanography andPrinciples of Biology. In each case the softwarelets students manipulate simple simulations (oneecological, the other biochemical) to determinehow changing one or more of the interdependentcomponents will affect the entire system. Thissoftware package can be used with a minimalamount of computer instruction and can be usedsuccessfully by students with no previouscomputer experience. This presentation will showthe development of A simple ecosystem model andan enzyme system simulation, and discuss howeach of these can be manipulated hy students ti*:\..t!.jr the.r i;nder>tund:r.g uf the unjcrljingr . i . . : J . J J . c.ir.c---..v

TliACIIINil CiKAIMlATI: .SI UI)i:.\'IS "IX) 'il-ACll.DM.* SilvcnU>i:i ami k H. Uuskiik. Univ. oM'cxas,Austin.

I'rcnuiing graduate students al research institution!, tobecome leaching faculty mcmbeis has been neglected untilrecently. As pan of a muvcisity maiukuc and wilii theassistance of tlic University's Cc:.lcr for TeachingEffectiveness (CTli), we have developed a scniesler-lougscmin;ir for new giaduate students. The slated courseobjectives arc (I) to develop leaching skills and awarenessof diverse leaching and Ic.uning stylos: (2) lo piovidc aforum and network for discussing teaching problems andissues, and (3) lo K!;' c;;ch pailicip.iut miualc his/her ownteaching poilfuho. The topics discussed are rclev.uil to thesluilc.ils botli ;_s graduate teaching assisl.uik ai:d as futurefaculty inembcis. They r:u:go fiom voiv practical m.iUerslo U.c more abstract :jid philCJ>up;.ie.il mciudiug academicdishonesty anil scientific ethics. We luvc combinedcxtei.sl'.e resource material provided by tile Cl'l; withhanJuuis we develr.ped U.at arc moic peiliueM to Uiebiological sciences. Inicgr.il to ll.e uuiisc :ue tile ien-minule- "nucioteach" sessions in which e:ich studentteaches a topic to the class. Cfciss members critique tliepresenting:. :md tie sessions ;ir; videul;.pcJ for tiie sludemto review Liter Groups ol sludci.ls develop active learningina:eri:J suci; as student "plays" :mj dcmonstijiijns. 'I hegraduate sluJent-s cnjjy Lie cour,e ai.d t'eel duit u allo.vsllicm to :uilicip..le problems v\hieh may .vise in d;eirleachii.g. Si:ppjr.eJ in jsu-t by NSF gr.jil i'l 1 fiAC:'.S'J2.


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Environmental Endocrine Disrupters

336 337EFFECTS OF ENVIRONMENTAL ENDOCRINEDISRUPTERS ON REPTILES AND AMPHIBIANSlimit 1). rainier*, Sylvia K. Palmer, and K)le W.Selcer. Dcpl. of Biol. Sci., Ohio Univ. and Dcpl. ofBiol. Sci., Duqucsnc Univ.

Environmental endocrine disrupters pose aninsidious risk to wildlife and humans. By mimickingendogenous hormones, such as estrogen, thesechcmicils can impair rcproduciivc processes in adultsand cause permanent damage to developing embryos.Viicliogenin, the precursor to egg yolk, is an csirogcn-mduccd scrum protein that is useful as a biomarkcr forxenobioiic cslrogcn exposure. A Universal VitellogcninAssay is under development in our laboratory. Thisimmunoassay utiii/.cs antibodies generated againstpcpiidc sequences representing conserved regions ofthe vitellogenin protein. The assay was used to examineIhe effects of xcnobioiic estrogens both underlaboratory and field conditions. In the laboratory, malereptiles and amphibians produced vitcllogcnin in adose-dependen! manner when exposed to eslradiol-17p\Similar results were obtained using both artificialestrogens, such as dielhylstilheslrol (DES), andcnviionmcntal estrogens, such as the pesticideo-p'DDT. These results demonstrate thai thesechemicals are esirogcnic in rcpliles and amphibiansEndocrine disrupling chemicals may be impactingreproduclion and embryonic development in wildpopulations, and may be partially responsible for thedecline of many species, such as ihe global decline ofamphibians.

ENDOCRINE-DISRUPTING ENVIRON-MENTAL CONTAMINANTS ANDREPRODUCTIVE ABNORMALITIES INREFRLESL.J. Guilletle, Jr.*, D.A. Crain, D. Pickfordand A. Rooney. University of Florida,Cainesville, FL.

Environmental contamination ofreptiles is associated with (1) populationdeclines due to lethal and reproductiveeffects of the contaminants in embryos oradults, (2) developmental abnormalities ofembryos, including major teralogeniceffects in turtles and more subtle effects onthe development of the reproductivesystem of alligators, and (3) abnormalities ofthe endocrine system. We examine thedata available on xenobiotic-inducedabnormalities of the reproductive syste?n inreptiles. We present a hypothesissuggesting that compounds that disrupt thenormal steroid miiieu of the developingembryo will induce life-long consequenceson sex determination and the organizationand function of the reproductive system.

339 341ADRENAL LESIONS IN ST LAWRENCEBELUGA WHALES AND THEIR POSSIBLERELATION TO ORGANOHALOGENSDe Guise, S.\ S Lair, M Fourmer, D. Martmeauand P B6land. UQAM. Montreal, Unrversite deMontreal. St-Hyacmthe, and St LawrenceNational Institute of Ecoioxicology, Montreal

A high prevalence of adrenal gland lesior.s wasfound in stranded beluga whales Irom theendangered and highly contaminated St.Lawrence population Two typos of lesions werefound: hyperplastic nodules, morphologicallyintermediate between hyperplasiic foci andadenomas, and serous cysts, that have neverbeen described in domestic animals. Thesecysts, appaiently similar to those reponed inwhite-sided dolphins (Lagenorhynchus acutus),would involve hydropic degeneration of clustersof adrenocortical ceils. Different etiologies wereidentified as potential explanations 'or theselesions: 1-Organohalogen metabolites known toinduce cortical degenerative lesions in variousdomestic species, 2-Siress, which producesadrenal hyperfunction, and 3-Normal ageingprocess

INTRODUCTION: THE NEONATAL MOUSEMODEL FOR HUMAN OFFSPRING EXPOSEDTO DES AND TO ENVIRONMENTALESTROGENS.H.A. Bern. University o! Calif., Berkeley.

In the early 1960's, experiments onneonatal mice indicated that early exposure tosex hormones during a critical period ofdevelopment could lead to permanent,longterm effects including tumorigenesis. Inihe early '70's, early intrauterine exposure to asynthetic estrogen (diethylstilbestrol, DES) wasfound to be the cause of vaginal cancer andother reproductive tract changes in humans.At the time of their discovery, thesephenomena were both novel and inadequatelyappreciated. Exposure to environmentalestrogens could have similar developmentaleffects in both mice and humans. Thisintroduction will emphasize the utility j f theneonatal mouse model for the analysis of thispossibility and will describe newly-deiineatedand cryptic changes in both reproductive andnon-reproductive organs which may be relevantto human disease. (Aided by N.I.H. andZenyaku Kogyo Co.)

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DEVELOPMENTAL MALE AND FEWiLE REPRODUCTIVETOXICITY OF D1OXIN.R.E. Peterson*. Univ. Wisconsin, Madison,in t roduc t ion by B.D. Palmer.

The ir.aternal dose of 2 ,3,7 ,8 - te t rach lo -rodibenzo-p-dioxin (TCDD) that adverselya f fec ts male reproductive funct ion fo l low-ing i n utero and lec td t iona l exposure inthe ra t is l/10Oth of that required whenexposure occurs in adulthood. This f ind ingis c r i t i c a l in assessing the reproductiver i sk of TCDJ becaue i t demonstrates thatprenatal and ear l y postnatal exposjre ish igh ly sens i t i ve to this type of t o x i c i t y .Developmental mele and female reproductivet o x i c i t y occurs in rats and hamsters f o l -lowing in utero and lac ta t iona l exposureto TCDD. Signs of t o x i c i t y in male ratsinc lude: delayed tes t i s descent and prepu-t i a l separat ion; decreased accessory sexorgan weights; decreased spermatogenesis,epididymal sperm numbers and ejaculatedsperm numbers; p a r t i a l l y demasculinizedand feminized sexual behavior and p a r t i a l l yfeminized regu la t ion of p i t u i t a r y LH secre-t i o n . One of the most sens i t ive e f f e c t s ,reduced epididymal sperm numbers, is causedby a s ingle maternal dose of TCDD aslow as 64 ng/kg. Toxic signs in femalerats and hamsters consist of urogenitalmalformations characterized by c l e f t i n gof the c l i t o r i s and a permanent threadof t issue over the vagina" o r i f i c e .

344

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Invertebrate Feeding Biodynamics

364 365

CLEARANCE RATES AND

CHEMORECEPTION IN DAPHXIA:

TECHNIQUES FOR DIRECT

OBSERVATIONS.

Strickler, J.R.*, L. Saluz1, J. Reimerand CD.

Sandgren. Univ. Wisconsin - Milwaukee, and '

Swiss Federal Inst. Technol. Zurich.

Aquatic ecosystem modelers rely on data

for clearance rates of Daplmia winch were

indirectly measured rather than directly

observed. Again, on the basis of indirect

measurements, cheinoreception was ruled out as

a criteria for food selection Now, with modern

optical techniques we directly observed not only

clearance rates but also 1) where, in a iarge

volume of water. Dapluita takes its food; 2) how

grazing depends on the larger scale swimming

behavior; and 3) if cheinoreception helps in the

detection, capture and ingestion of food items.

All results will be shown in a full-!en<!t'.i video.

FLUID KECHANORF.CEPTION IN :1AR1NE COPEPODS:SIGNALS, SENSORS, SENSITIVITY,i eanne t t c Yen (Marine Sciences ResearchCenter, S t a t e Univers i ty of New York,Stony Brook, New Ycrk 11794-5000).

Copepods roam in a 3-dimensionalaqua t ic environment and t h e i r s enso r sreflect chis: setal hairs on t'.ieir pairedantennules are oriented in 3 orthogonalplanes Lo intercept fluid Clow in thuscdirections. Behavioral responses indicatethat some copepods use these sensors forfluid mechanoreccption. We have examinedthe ability of a carnivorous copepod toremotely detect fluid deformationsproduced by mobile prey which permitearly detection of prey by the predator.This involves both target recognition aswell as 3D spatial localization ofhydrodynamically conspicuous prey. Wemeasured neurophysiological andbehavioral responses of the copepod tostimuli that have been designed to mimicdisturbances generated by their prey.Through empirical observations with flowvisualisation techniques, we ascertainthe component of the velocity field thatcan be detected by the copepod. This isdemonstrated as an elicited response: aturn while swimming, the capture of prey,an escape from a predator.

366

QUANTIFYING FLOW THROUGH DYNAMICALLY-SCALL'D PHYSICAL MODELS OF SUSPENSION-FEEDING APPENDAGES.M. A. R. Koehl. Ur.xv. of California,Berkeley.

Many animals from different phylause appendages bearing arrays of h.tirsto capture pnrticulate food from Lhcsurrounding water. We have been usingdyr.araica] ly-scaled physical models tostudy how the morphology, size, andkinematics of such feeding appendagesaffect the fluid flow around andthrough them, and hence determine thephysical mechanisms of food capture.Our flow visualizations have revealedconditions under which there is per-mission for morphological diversity•Jthout performance consequences, versus

nditions under which simple changesn size, speed, or racsh coarseness canlead to novel mechanisms ofoperation.

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373 374

MATING SYSTEMS OP CEl'HALOPODS:CONTRASTING STRATEGIES AN'D THEPOSSIBLE INFLUENCES OF SPERM COM-PETITION BEHAVIOR.R.T. Hanlon. Marine LJiomedical Institute.University o!" Texas Medical Branch, Galvcs-ton.

Squids and cuulcfishcs (decapods) sharemany characteristics in terms of extensivemale-male competition, courtship, multiplemates and mating styles, and lack of parentalcare. Octopus mating systems differ exceptthat both sexes mate with multiple partners.All female cephalopods store sperm. Femalechoice in decapods seems well developed:females assess males during male-male ago-nistic contests and during courtship; femaleschoose when to fertilize and lay eggs; andfemales choose which sperm to use, from thecurrent mate or from storage. Individualswithin a species have variation in their repro-ductive strategies, and analyzing mating sys-tems in the context of speim competition be-havior helps to clarify complicated issues suchas male fighting tactics, temporary pairing,extra-pair copulations, variable delays betweenmating and egg laying, and tcmpoiary mateguarding

LEARNED AVERSIONS TO FOODODORS IN LAND HERMIT CRABS,COENODITA COMPIiESSUS.R. W. Thacker. Univ. of Michigan,Ann Arbor.

Land hermit crabs are more attracted tothe odors of foods they have not recentlyeaten than to the odors of foods they haverecently eaten. These induced food odorpreferences are associatively learned.This study distinguishes between twoproposed mechanisms of associativelearning: a learned avoidance of foododors and a learned hunger for specificnutrients. Crabs were offered odorchoices after experience with cithernatural foods high in protein orcarbohydrate, or artificial foodscontaining protein or carbohydrate thatwere paired with odors from naturalfoods. Nutrient type did not affectsubsequent odor choices. Crabs avoidedthe odor that was paired with t-he foodthat they had recently eaten, regardlessof that food's nutrient type. These resultssuggest that learned aversions to foododors arc responsible for land hermitcrab food preferences.

375 376

THE VISUAL CONTROL OF BEHAVIOR INFlDDLHR CRABS; II. TRACKING CONTROLSYSTEMS IN COURTSHIP AND DEFENSE.Land, M.F. and J.E Laync*. University of Sussex.BricV.ori. UK. ir.d D\:ke L\ Mir.r.e Lib. S"iu;cr.. XC".

Male fuMlcr crnlis (Urn puyjlninr) li.we VIMI.I!coutiol systems ih;ti cn.iiilc it.em to tr;:ck oilier erahs mfrom or behind, and 10 keep potenu.il p.edauii.s to theside, wlieie escape i.s easiest The syMcin To: trackingccnspecilics is dominated by a low-gain velocity sensitisemechanism, but at the edges of ils range a posmon-sensitivc mechanism takes over, which rccenlcrs the target.This system has separate front and rear ranges, with a g.ipm the direction ol the claw. Predalor evasion employ.* iwosystems simultaneously. A fc:d-forward mechanism directsthe crab's iranslatory movements directly away from thesamulus, and a rotational mechanism using continuousfeedback turns the crab so that the stimulus is kept at near90 degrees to the body axis Both systems arc sensitive tothe angular position of the .stimulus, no; us velocity.

MALI! CHOICE AND SIZE-ASSORT ATIVF.MATING IN THE ORB-WEAVF.RTET11A CNA THA EL 0/v CA TA.Danielson-Francoii, A.M.*and P.D.Sir.aUwoodSwarthmcrc College, and Biyn Mawr College,PA.

In the absence of male:ma!e competition,size-assortative mating may depend c:i thedegree of size difference between male andfemale spider. In Tctra^naiha elongata. maturefemales tend to be larger and heavier thanmature males. Females can and do somctitr.esoverpower and cannibalize males after mating.

Males prefer to mai. with the lr.rgerfemale when given a choice of two females,despite the risk of sexual cannibalism. Thispreference may be explained by increasedlecundily of laiger females.

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377 378EFFECTS 0! ; MULTI-SPECIESINTERACTIONS OX WATER STRIDLIiMATING DYNAMICS.A. Sill* and J.J. K-iupa (introduction b\ J. Just).I'niv. of Kciuuck\. Lexington.

Predatory sunfish can have stionu cfleets on themating behavior (matin;; frequency, matingduration, mating activity, non-random mating bysue, male-femaie inteuclions) ol"a stream waterstrider, Aquarius rcmigis. Many of these effectsseem at first glance, counter-intuitive, but arcexplainable in terms of mule-female belia-.ioralconflicts, in particular, variations in femaleresistance io male harassment of females appearsto play a key role in explaining matin;.; patterns.The effects of sunfish on water striders, how ;ver,depend on complex multi-species interactions.That is, sunfiiii effects depend or,: 1) water strideidensits. 2) inleiactions between sunfish and otherfish - minnows >T iLirtcis, :ind 3) othv-r predators,e g , fishing spideis Overall, stream water stridermating dynamics appear to be remarkablyresponsive to \ari:.tions in the communi'y inwhich ike specie.-, is embedded.

Why die endothermy evolve whenit car. cost up to 757 of basalmetabolic rate? Two hypotheses,maximization of aerobic capacityand niche expansion, have beenproposed. However, sexual selec-tion for increased metabolic acti-vity is a selective force that hasnot been thoroughly investigated.Er.dotherir.y is ubiquitous in mammalsand birds, but heterothermy hasoriginated at least six times xnthe insects. Research on the evol-ution of heterothermy in inverte-brates is essential to understan-ding the origins of endothermy.The mating behavior of owl' butter-flies Caliqo is unusual in thatmales aggregate at dawn and dusk,shiver to elevate body temperatureon perch sites, and engage othermales in territorial contests orcourt females. Shivering was notnecessary for flight activity, andbody temperature was correlatedwith aggressive activity towardmodels. h comparative analysis ofother insect groups that exhibitheterothermy indicates that it isoften associated with sexualdimorphism and male-male combatfor territories and mates.

379 380

UNDERWATER ACOUSTICAL SIGNALSIN A NEW SPECIES OF NORTHAMERICAN RANID FROG: ANASSESSMENT OF CALL VARIATIONAMONG MALES.J. E. Platz*. Creighton Univ., Omaha, NEand C. Bell/., Wesleyan Univ., Lincoln, NE.

Preliminary analyses of the vocai repertoireof Rana subaquavocalis, resolved threecommon call types similar to those offeredby other species of ranids whose calls areairborne signals. One of these, a snore-like,amplitude modulated signal has beenassessed for several adult males from onepopulation for five call parametersincluding call duration, pulse number,pulse rale, pulse duration and dominantfrequency. Of these five, hvo (pulse rate anddominant frequency) have much lowercoefficients of variation suggesting that theyare "static" call parameters in the sense ofGerhardt's assessment in 1 lylid frogs, whilecall duration, pulse number, and pulseduration have high coefficients of variationand are therefore "dynamic" parameters.

ARGININE VASOTOCIN EFFECTS ON SOCIAL/AGGRESSIVE INTERACTIONS IN CALLINGBEHAVIOR OF THE MALE CRICKET FROG {ACRISCREPITANS ). J. Chu, W. Adham and W.Wiiczynski*. University of Texas at Austin.

Male cricket frogs form laige breeding choruses inwhich calling serves to attract females and to repelmales from encroaching on calling sites. Weexamined the effects of arginine vasotocin (AVT) onmale calling in the context of a social/aggressiveencounter. Calling males were tape recorded theninjected with AVT (10ug/g, BW; N=13) or anequivalent volume of saline (N=15) and returned totheir calling sites After 30 minutes, males wererelocated and a speaker was placed approximately30cm from the animal. A repeating, digitizedconspecific call was broadcast for 5 minutes. Thema'e's calls ware recorded during the auditorystimulus (Playback condition), and for 5 minutesfollowing the stimulus (Post-Playback condition)Comparisons between AVT and sal.ne injectedanimals indicate several significant diffeiences incalling behavior. The number of calls were higher inAVT animals during both the playback (p<.05,unpaired t-test) and post-playback periods(p<0.0001). The post-playback period also containeda higher number of calls per call group, and a higherrate that call groups were produced (p<0.001). Inaddition, latency to begin calling in the Post-Playbackcondition was much shorter in AVT males (p<0.0001).AVT is knov/n to facilitate reproductive social behaviorin amphibians. These results suggest '.hat AVT canalso increase aggressive calling in this species.(Supported by NIMH T32 I/.H18837 )

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381 382SOCIAL SIGNIFICANCE OF DORSAL COLOR IN ATERRITORIAL LIZARD. Sa-lpnorus undulates. I..C.Sciu* and II.D. Jolm-Aldcr. Rulgcrs Univ., Piscalaway, NJ.

We have been investigating how an animal's socialenvironment affects a correlated suile of traiLs that underliefitness components, including communicative pigincnlalioiand exercise stamina. As part ol ihi.s 1,-irgcr study, weinvestigated social interaelions in pairs of adult maleScelopnnis undula(i)*; housed in small outdoor enclosuresPairs of size-matched li/anls were held together for 40 daysbeginning in the latier half of Hie breeding season. Toencourage (lie formation of dominant-subordinaterelationships, resident (R) males were placed into enclosures7 days before the introduction of intruders (I). Behavior anddorsal pigmentation were observed regularly, and blood wassampled periodically for steroid hormone assays. Behavioralresponses to the lnuoduclion of females (F) wcie observedfor 30 Min. on both days 26 and 32. Upon die inlioductior.of I, R won the initial aggressive encounter in 10 of 11 pairs(Fisher's Exact Test, p < 0 0001). Subsequently, ovenbehaviors between male.-, were not evident. At the lime ofintroduction, we failed to oliscivc differences in doisalpigmentation between R and 1 By day 10, 6 K and 5 I wereconsistently ligliicr :u appearance than the other member ofthe p;ur. Upon the miioduciiun ol !•'. we observed couilshipin 9 and X of (he 11 paiis on days 26 and 32 respectively. Inall cases the ligliicr colored in.i.e W;LS the si.i'.ui (p < 0 0!)lfor each introduction). In 8 of diese 9 cases, the same lightdorsal colored male courted Fupon botli introductions. Ourobsci \ alions .suggest that male Sceloron:s umlulauis mayuse dilfcrences in dorsal pigmentation to communicate socialstatus even in the absence cifovci I behavioral displaysSuppoucd by Use Oiaiics anj Joanna Busch Fund.

PLANE GEOMETRY FOR NAIVE SEARCHERS: SOMERESULTS OF THE SIMULATION RatileSnake®.D. Duvair, D. Chiszar and R.A. Mintzer. ArizonaState Univ. Woo!, Univ. of Colorado, Boulder, andUniv. of Chicago.

When searchers have little or no knowledge ofthe location in two dimensional space of resourcesunits (= "targets") they seek, how should theymove? Should they move in a random walk,travel along a straight line, or something inbetween? And would efficacious search paths--shouid any exist-vary for populationsencountering different sorts of large! spatialdistributions7 Many kinds of living thingsencounter just such problems commonly,including some of the rattlesnake populations westudy. In our simulation Rattlesnake© forMacintosh, we have found that search paths ofhigh vector magnitude maximize collisions withtargets in clustered but not uniform or randomarrays (the three known kinds of spatialdistributions), particularly when targets arewidely distributed. Random walks of low vectormagnitude are always effective when targets arenot widely distributed, however, so long assearchers can afford the temporal and energeticcosts of such extensive movement. It appearsgsneraliy, therefore, that some search paths arefavored in some statistical distribution0 ofresource units and not others.

383 384

ASSESSMENT OF RATTLESNAKEDANGEROUSNESS BY CALIFORNIA GROUNDSQUIRRELS: INFORMATION EXTRACTION FROMRATTLING SOUNDSR R. Sv.aisgood", M P. Rowe and D.H. Owings Univof California, Davis, and Appalachian Slate University,Boono

Because ground squirrels frequently placetnemsolvcs at risk by harassing rattlesnakes, theystand to benelit Irom assessment strategies whichserve to med.ato risk For exarrple, larger and warmersna!<os are more dangerous than smaller and colderones, and rattling sounds contain cues which divulgeinformation regarding snake bcly temperature andsize. Thus, it would behoove squirrels to utilize tinsinformation vhen they encounter rattlesnakes,exercising greater caution with more dangeroussnakes. To determine if squirrels adopi this strategy,wo played back rattling and control sounds to apopulation of free-living squirrels. The squirrels clearlyassociated rattling sounds with rattlesnakes andappeared capable of assessing both snake bodytemperature and size v,a acoustic cues. Squirrelsdiscriminated among rattling sounds on the basis ofseveral behaslcral measures, including tail flagging,bipedal posture, and hes.tancy to reapproach the areawhere the rattle v;as heard Many of these behav:oraldifferences were sustained for up to 10 minutes post-playback. Moreover, maternal females, in comparisony.ith males and ncn-rnaterna! females, responded morestrortgSy to rattling sounds and were more sensitive tocuis revwal.ng sr.r.ke darrjcro'jcr.ess Appn'nrr.y,mothers .rives: mere !n ar.ti-ratt! .snake beliav.cr

cs or hon-hiatcnia, lc.::alcs

SPACING PA'JTEFKS IN THE STH1PED SUNK.A. Bixler* and J.L. Gittlercm

One of the rxst cannon spacing pat-terns within the Carnivora is intrasex-ual territoriaiity, whereby males possesshone ranges exclusive of other males andfemales possess hone re .ges exclusive ofother females but males overlap with fe-males. Considerable variability has beenfcunc1 within the conte>:t of this spacingpattern. For striped skunks (Mephitismephitis) , tv.o different patterns havebeen suggested: 1) females overlap withmales and each ether, while males main-tain ranges exclusive of each other, or2) rales ard females possess hor.B rangeswhich overlap between and within thesexez-. We report twj ysars of teleretxydata on striped skunks in Crcat SmokyMountains National Park. Both sexes ap-peal' to overlap home ranges inter- andintra-sexually, scene by more than 90S. oftheix total range. Results presentedhere are part of an ongoing study of howsolitary spacing patterns are associatedwith gcnDtic relatx>dr.ess and what rrech-aniars (specifically, scent marking) oreinvolved in rr.\rtairiing spacing patterns.


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WEATHER PATTERNS AXDTIIEBEHAVIORAL ECOLOGY OF BABOONSA. M. Bronikowski and J. Alimann. U. of ChicagoTo investigate the relationship between the

behavioral ecology of sa\arina baboons (Papiocyiwccplutlus) ami meteorological variation, weanalyzed 10 years of data for three social groups,two natural and one garbage-feeding, from apopulation of baboons ir. Amboseli Park, Kenya.Temperature and rainfall data were collected duringthis time period, as well as annual daily traveldistance and activity budgets (feeding, moving,socializing, and resting times) for the adult femalesof these groups. For :he two natural feedinggroups, the significance and directionalities of thecorrelations with meteorological \anablcs wereinconsistent. The behavior of the garbage-feedinggroup did not correlate significantly with anyweather variables. Multiple regression models ofrainfall and temperature variables on foraging timewere significant for the two natural feeding groups(p <0.05, p<0.005) but not for the garbage feedinggroup (p<0 98) An analysis of variance ofpercent of daytime spent foraging (feeding plusmoving) revealed significant fixed effects of month(F=2.5"l. oi = I 1. p=0.0!) and gioup il-=202.47,df=2. p=0.00011 ar.cl a significant ycai'*groupinteraction (F=2 51. df=S, p=O.OIS). Thus, thesocial groups within a population of baboons thatexperience the same weather patterns may responduilfeienily to annual and monthly variation inweather patterns, perhaps due to different resourcebases

MALH MATING SI RATCGIES INPOLYANDROUS GROt.'PS Ol- \VH1T[>V.TNGED TRUXiPinT.RSSherman, Pclci T Noitr.c.isl Louisiana \.\\\\ ,Monroe

Dillcicnccs in mating .strategic* betweenindniduals within cooperatively breeding groupsh.ivc seldom been investigated because ol thedilficuily D! observing copulation* in most speciesThi.- studs examined the mating strategics ofdomin;.il and subordinate males w iihnici)i>poi.ili'ic')> biccdmg groups ol while-ningcdtrjiTi|x:tcrs living in Manu National Park insoulheaslein Peiu In liumpclcr gioups, onl\ llicdominant female bred, and she rcadiK copulatedwith both dominant and subordinate adult malegroup mcnibcis There was intense competitionamong males, aad both dominant and sub'oidmatcmales attempted to inlenupt each othci's copulationattempts during the Icmalc's Icililc pciiix!Strategics cmp!o\cd by males Juring avpuiationattempts v:uii\! according to the male's dominancestatus. Dominant males attempted to guai J thefemale iluiiiij her Icrtilc pcinxl, and copu'.ated withhei c\cn wiicr. suboidinalc males wcie in closepioxinnt) In (.oiitiasl. subordinate m.iles copulatedsuiieptitioasiy and lapidly, taking advantage ofmonxnls vhen the dominant male w.is ielali\cl\ larI"iurn the lemale or engaged in a:i activity that madeit dilltcult for him to uatch the female Althoughthe dominant male completed significant!) morecopulations, subordinate males accounted foi about30'.'!. of the successful copulations dining liieInnaic's ierliie pciiixl

387 388

Tl ItiKISK Ol"( (JCKOLDKY ANDTERRITORIAL Uiit; PATfLRNS l.\ THEWILLOW FI'ARMIGAN (LACK'PUSLAGOITS)Peni K liison anil S j liannon Nortlu1 islLouiv.an.i L.'ni\ . Moniocind Univ o! Alheila.L'dmriUon

This sLuiv e\;;miiies the patterns o! teiiitonal useexinbiied In maU willow pl.iiinigan alChilkal Pass.British Columbia, in oiue.i !o test the hjpolhcM.s th.ilbleeding teinloix M/C m.i\ bcdcleimincd in past byiiie usk of cucl-oldn Males' icmloiics ucicm.ipped M\\\ div ideu IIHO truce /ones: a boundtiiy/one (0 - Id m !ii>m .'. Ixnind.uy), an uilcimediate/.one (it)- 20 n°i lioni a boundai>),and a eoie /.one(> 2i' m liosn a bound.ii\) The bcliavioi olbacheloi and paued iiiales \sas then compaied1.-—II 1\ in the bleeding season hcioie lemale selllcd,all nule ptarmigan used the outer 10 m of theirlei I il(Hies e\lc:isi\c!\, on avciagc f±sc), bacheloimales wvic in llic btiuudaiy /.one 75.0'i (±9 4; ofthe lime and males th;;t l.ilcrobl.iined mates weic inthat /one 71..V. (±8 7) of the time. Altei thefemales had settled, in conliasl. although baelieloiscontinued to use piimaiiiy the L.>unil:ii\ /ones olthen Iciiiioitcs, paired m.ilcs shiSled to 'he coics oltheir terntoii-.".. !2aehel>/is then spenl SS-i'.' ( i4 <•)>'!" their time ncai bouiuianus, nhiie panedmales s;x-nt lJf> 4'! (±2 5) ol their tune in the colesof tneir icniloiicv These data suggest th,il maleguaidmg is a significant luncCon ol teiiiloiiahl) andthat the lisk ol cuckoidi; may he a pnman «-elixiivcloicc Jnvii'.g i!:e JelViise ol !..ige icmtoiics

EFFECTS OF SEXUALLY TRANSMITTEDDISEASE ON HERITABLE VARIATION INSEXUALLY SELECTED SYSTEMS.8.M. Graves* and D. Duvall.Northern Michigan Univ., Marquetteand Arizona State Univ., West,Phoenix. »

We present a new hypothesis thatcould account for maintenance ofheritable genetic variation in bothmale traits and female choice insexually selected systems. In po-lygynous mating systems, males withpreferred traits, and females thatchoose to mate with such males,will have high probabilities ofcontracting sexually transmitteddisease during epidemics. Animalswith these genotypes will experi-ence reduced fitness. Concurrently,genotypes associated with lesspreferred males and less choosyfemales will be more likely to passthrough genetic bottlenecks pro-duced by lethal and sublethal sexu-ally transmitted disease effects.After such a selection event, sexu-al selection cculd again act ongene frequencies to move them backtoward equilibrium conditions. Thisprocess could result in sporadicgene frequency fluctuations withinsemi-isolated domes.

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390 391SEX-SPECIFIC DIFFERENCES INANDROSTENEDIONE METABOLISM IN GONADALTISSUES OF l.rrF.CHlNlUS IAR1EGATVS INRESPONSE TO FEEDINGKM. Wasson*. G.A. Hincs. J.B. McClinlock. and S.A.Walts. Univ. of Alabama at Birmingham, Birmingham

/.yiechmui varicgatus were collected from St JosephBay, Florida in January (at the onset of gonadal growth)and starved for 42 d, followed by feeding ad lihilum for48 d. On days 0,4.8,16,32 and 48 of feeding, gonadaltissues were excised and were incubated with 'H-androslcncdione for 0.5 h Radiolabclcd steroidmetabolites were tentatively identified using TLC coupledwith radioisolopc image analjsis. product dcrivali/ations.and rccryslalli/iUion. Both tcsticular and ovarian indicesdid not increase significantly until aflcr day K>. Totalconversion rales were similar between tcslcs and ovaries,however sex-specific differences in -^ll-androslcncdioncmetabolism were demonstrated In boll) the testcs andovaries, the major steroid metabolites were testosteroneand 5a-androstancdiol with lesser accumulations of other5a-rcduccd androgens. Accumulation rates oftestosterone and 5a-andros(ancdiol in the lestes peakedby day 4; 5or-androstancdiol accumulation decreased byday X In contrast, testosterone did not accumulate in theovaries until day 8, however 5a-androslancdiolaccumulated rapidly by day 4. similar to theaccumulation pattern observed in the tcslcs Thephvsiologocial significance of the carl) surge in 5a-androslancdiol formation and accumulation is not known,but ma) be related to the initiation of biosynthcticprocesses prior to tissue growth. Supported by NSFEHR-9108767

SITE AND REGULATION OF VITELLINSYNTHESIS IN THE BLUE CRAB, CALUNICCTESSAPIDUS.C.-Y. Lee*, H.R. Umphrey, and R.D. Watson.University of Alabama at Birmingham.

Tissues (ovary, hcpalopancrcas. gill) from ndullfemale crabs {Cnlliiicctcs sti/mlus) were incubated invitro wilh p^Slmclhioninc. After incubation, tissueextracts were separated by SDS-PAGE andradiolabclcd proteins visualized by auloradiogmphy.Four radiolabclcd ovarian proteins (188, 168, 109 and86 kDa) comigratcd with the subunils of vilcllin (Vn).A Western blot analysis confirmed that these ovarianproteins were the Vn subunils. Proteins in thehepatopancrcas and gill were also radiolabclcd, butwere not Vn-immunorcaclivc. In vitro incorporation ofp - SJmcthioninc into ovarian proteins was inhibited byan extract of eycslalks; the inhibition was dosedependent and tissue specific. Autoradiography ofclcclrophorclically separated ovarian proteins showedthat the eyestalk extract inhibited |-15S|mclhionincincorporation into many ovarian proteins, includingVn. The global inhibitory effect of the extract onovarian incorporation of |35S]melhioninc wasconfirmed by a dcnsitomctric analysis of theautoradiogram. These rcsulls suggest thai the ovary isa silc of Vn synthesis, and that Ihc cyeslalks conlamfaclor(s) that directly inhibit ovarian protein synthesis(Supported by MS-AL Sea Grant NA16RGOI55-03).

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EFFECTS OF PROSTAGI.ANDIN E2 AND METHYL FARNESOATI;

IN DISTINCT REGIONS OF MACROBRACHIUM ROSENUERG1I

PRE-viTELLOGENlc OVARY. A. Sagi*, Y. Soroka1, J.Silkovsky, Y. Milncr', and R. Chayoth. Bcn-GurionUniversity, Bccr-Slicva, and 'Hebrew University.Jerusalem, Israel.

Eicosanoids and juvenile hormones have beensuggested to have a role in the regulation of crustaceanreproduction. Methyl farncsoatc (MF), a juvenilehormonc-hkc compound, is present in the hcmolymphand tissue of M. rosenbcrgii and has been demonstrated toexert its highest stimulatory effect in vitro on ovarianprotein synthesis during the prc-vitcllogcnic stage.Prostaglandin E2 (PGE2) is present in the prc-vitcllogcnic ovary of A/, rosenbergii, its bioconvcrsionfrom arachidonic acid in crustacean ovaries is related tothe progress of the vitcllogcnic process

Prc-vilcllogcnic ovaries were dissected andfragmented into three distinct regions (anterior, centraland posterior), and m vitro incubated with PGE2 or MF.Ovarian cAMP levels in the tissue were measured usingRIA. Protein synthesis was estimated by incubation wilh[35S]-mcthioninc.

PGE2 stimulation of cAMP synthesis in anteriorand central regions was three times more than in theposterior region. MF did not aJTccl the levels ofcAMP 111any part of the ovary. MF stimulated protein synthesis inanterior (25.5%) and central regions (13.2%) of the ovarywhile no effect was recorded in the posterior part.

The cellular response to hormonal stimuli is notuniform in different regions of the o\an the c\annntissue is moic susceptible to hormonal cffixi toward ilsanterior region.

MELATOMIN IN INSECT NERVOUSTISSUE AND H E M O L Y M P H .T i l d e n , A.R.*, V.H. H u t c h i s o n ,W.J. A n d e r s o n , and J. War e s .University of Okl a h o m a , Norman,and M a c a l e s t e r C o l l e g e , St. P a u l ,MN.Melatonin (MEL)'-level § were m e a s -ured with radioimmunoassay (RIA)in two species of damselfly,Ischnura vertical is and Enal1agmac i v i l e , and in the tobacco horn-worm, Manduca sexta. In damse l -flies, MEL was found primarily inthe heads (nervous t i s s u e ) .I. verticali s had higher MELlevels during s c o t o p h a s e ; E ^civile had no MEL cycle. InM. sexta, MEL was measured inhemolymph, and we found a sig-nificant peak during s c o t o p h a s e .MEL may be an important trans-ducer of environmental informa-tion in invertebrates as wellas v e r t e b r a t e s .

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CELLULAR EVENTS THAT REGULATEECDYSONE PRODUCTION IN THETOBACCO HORNWORM, MANDUCASEXTA.S. Ackerman-Morris and W.A. Smith*.Northeastern University, Boston, MA.

The prothoracic glands of the tobaccohornworm, Manduca sexta, produce ecdy-steroids in response to prothoracicotropichormone (PTTH). We have found that invitro exposure of the prothoracic glandsto the benzodiazepine agonist Ro5-4864increases the production of ecdysone.Further, benzodiazepine agonists appear toenhance movement of radiolabeledcholesterol to the inner mitochondria!membrane. In addition, PTTH-stimulatedecdysone secretion in vitro is blocked bythe microtubule inhibitor nocodazole butnot by the microfilament inhibitorcytochalasin B. The results suggest that theintracellular movement of ecdysteroidprecursors may be mediated bybenzodiazepine- and microtubule-linkedtransport systems, as has been proposed forvertebrate steroidogenic cells. Supportedin part by NIH grant DK37435.

JUVENILE HORMONE REGULATION OF ITSBINDING PROTEIN IN A MUTANT STRAIN OFTHE TOBACCO HORNWORM, MANDUCA SEXTA.A.P. Orth* and W.G. Goodman. Univers i tyof Wisconsin - Madison.

J u v e n i l e hormone I (JH I ) was appl iedexogenously t o l a r v a e of the low-JHblack s t r a i n of Manduca s e x t a and t o t a lp ro t e in and hemolymph j u v e n i l e hormonebinding p ro t e in (hJllliP) responsesdetermined. Jll I doses in the phys io -l o g i c a l range of w i l d - t y p e l a r v a e , from1 to 1000 pg, induce hJHBP t i t e ri n c r e a s e s from 50% t o 91% in t r e a t e dblack larvae; total protein is unaffect-ed by JH I treatment. The temporalresponse of hJHBP t i ters to JH Itreatment in black larvae shows that 12hours after JH I treatment, hJHBP titersdecrease threefold but that 44 hoursafter treatment, hJHBP t i ters exhibitthe near twofold increase observed inthe dose-response study. This complextemporal response suggests that regula-tors other than juvenile hormone parti-cipate in regulation of hJHBP t i ters inlarvae of the black strain of thetobacco hornworm.

396 397THE EFFECT OF EYESTALK REMOVAL ON METHYLFARNESOATE LEVELS IN THE JUVENILE FEMALESPIDER CRAB Liblnia emarginata

P.Takac, H.Laufer., J.Ahl., L.Liu andG.Rotllant. Department of Mol.&Cell.Biol.University of Connecticut, Storrs; MarineBiological Laboratory, Woods Hole, MA

In insects, JH functions as a morphogenin juveniles and as a gonadotropin in a-dults. Methylfarnesoate (MF) an unepoxida-ted JH in Crustacea is secreted by the mandibular organ (MO), a tissue homologous tothe corpus allatum (CA) of insects. In a-dult females MF cycles during vitellogene-sis. Thus MF seems to function in crusta-cean reproduction. MF synthesis is inhibi-ted by sinus gland (SG) factors. MF levelswere investigated in juvenile females of!>.emarginata following eyestalk ablation.MF increased sign'ficantlyin hemolymph ofde-stalked animals (2.6ng/ml) by day 20.In controls the range was (0.25-0.75ng/ml).Eyestalk removal significantly shortenedthe molt interval to 20 days compared to78 days in controls. All destalked juveni-le females molted into juveniles, whilecontrols became adults. The gonads remai-ned in both group unaffected.

We conclude that MF plays a role inmorphogenesis of the maturational molt inCrustacea similar to that in insects.

METHYL FARNESOATE (MO LEVELS DURING THEMOLT CYCI.E OF THE LOBSTER, Homarus americams.D. W. Borst*. P. B. O'Neill, B. Tsukimura, and J. Atcma.Illinois Slate Univ., Normal, California State Univ., Fresno,and Boston Univ. Marine Program, Woods Hole, M A .

Several reports suggest that the maiidibular organ (MO)may be involved in regulating the crustacean moll cycle. Toinvestigate tlic role of the MO in molting, we measuredhemolymph levels of ecdysteroids and MF (a product of ihcMO) in prcmolt lobsters. Animals were maintained in large(5600 liter) aquaria with fresh flowing sea water at ambienttemperature (17-21 C). Hemolymph samples were obtaineddaily and analyzed for both ecdysteroids (by R1A) and MF(by HPLC). During the last 13 days of prcmolt, ecdysteroidlevels rose from 357 ng/ml to peak levels of 1600 ng/ml.However, MF was undctcclablc in most samples, though lowlevels (0.6 ng/ml) were observed in a few (10%) of thesamples. Similar results were observed in samples obtainedin earlier prcmolt periods. Because (lie half-life of MF isshort (ca. 45 minutes) and MF is released episodically, wecould have missed MF being released in these animals.Therefore, we measured the in vitro synlhesis of MF by MOsfrom animals at different stages of the moll cycle. MOs wereincubaied in Medium 199 supplemented with 3M-methionincand the incorporation into MF measured. MF synthesis waslowest in postmolt animals and highest premoll animals.However, animals in early and laic stages of prcmolt hadsimilar levels of MF synthesis, in spite of a >10-folddifference in ecdysleroid levels. These data suggest that MFdoes not directly stimulate ecdysteroid production in thelobster. However, MF may have an indirect or permissiveeffect in the regulation of molting. (Supported by NSFGrants IBN-8919833 and IBN-9319206).

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398 399ECDYSTEROID AND RETINOID RECEPTORS IN THEEARLY BLASTEMA OF REGENERATING LIMBS IN THEFIDDLER CRAB UCA PUGILATOR.P.M. Hopkins*, D.S. Durica and K.L. Carter. Univ.Oklahoma, Norman.

Regeneration of walking legs in (he fiddler crab Ucapugilator represent*; true epistatic growth since it involvesorganization of an undifferentiated blastema prior to regrowthof a new limb. Normal regeneration in Uca consists of thretjphases - blastema formation, basal growth, and proecdysialgrowth. The latter phase is always associated with ccdysis andis, in part, under the control of ecdyt>ial hormones. The twoearlier phases appear to be independent of preparations foiecdysis but studies have shown them to be responsive tcecdysteroid hormones. Relinoic acid (RA) also affects cralregeneration. Crabs treated with RA in vivo regenerate more]slowly and are frequently malformed. Recently, an orphan,receptor has been identified in Drosophila that is thehomologue for one of the vertebrate RA receptors. Thtorphan receptor (USP) dimerizes with the ecdysteroid receptoi(EcR). Using sequence information derived from theDrosophila ecdysteroid receptor gene, we have isolated a crabcDNA clone containing the Uca EcR DNA binding domainThe nucleolide sequence is 76% identical (o the DrusophUtbinding domain and encodes six ami no acid substitution:clustered within the second zinc finger. Western blot analysisnative gel binding a ssays and RT-PCR indicate that expressionof the ecdysteroid receptor occurs early in blastema formationat times that correspond to cuticle deposition. Similar analysisshows that RA receptor expression occurs during earl)blastema growth. Ecdysteroid and retinoid receptors may worktogether to control early blastema formation during fiddlei

THE ROLE OF ECDYSONES IN THE MATURATIONALMOLT OF JUVENILE FEMALES OF THE SPIDERCRAB Llblnla emarginata

G. Rotllant, P. Takac, L. Liu, J.B.S. Ahland H. Laufer. Dept. of Mol. & Cell Biol.,Univ. of Connecticut, Storrs ; Marine Bio-logical Laboratory, Woods Hole, MA.

Eyestalk ablation in Crustacea accelera-tes molting. In juvenile female Libiniaemarginata eyestalk ablation also resultsin a failure to undergo maturation. Wewant to determine whether ecdysones playa role in the molt to maturity. We measu-red ecdysteroid titers in intact and abla-ted females by RIA. Methyl farnesoate(MF),a crustacean juvenile hormone, was alsomeasured (Takac et al., 1994) in such ani-mals. The ecdysone levels increased signi-ficantly in hemolymph, from 3.25 ng/ml inthe control animals to 116.04 ng/ml In thede-eyestalk animals after 21 d. All abla-ted juvenile females molted into juvenileswithin 29 d, while controls molted into a-dults within 67 d. Our results suggest ec-dysones regulate molting, and play a rolein maturation, while MF retains juvenilecharacteristics.

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OSMOREGULATION AND FMRFamide-RELA-TED PEPTIDES (FaRPs) IN THE MOLLUSKS:HEL1SOMA, MELAMPUS AND SIPHONAR1A.H.R. Khan*1, D.A. Price2, K.E. Doble2, M.J.Greenberg2 and A.S.M. Saleuddin2. 'York Univ.,Toronto, Canada and 2Whitney Lab., St. Augustine,FL, U.S.A.

We have used the air-breathing pulmonates:Helisoma from freshwater, Melampus from saltmarsh and Siphonaria from intertidal habitats ofFlorida to study the roles FaRPs in osmoregulation.Experimentally, their hemolymph osmolaritiesdecrease when these animals are kept in media oflower osmolarity. The threshold of osmotic tole-rance for Helisoma is 0-11 % sea water (SW), forMelampus is 10-120% SW, and for Siphonaria is30-120% SW. Tracer studies suggest that thekidneys are the primary sites of urine formation.The smooth muscles of the kidneys are innervatedby serotonergic and FaRP-immunoreactive axonsfrom the visceral ganglion of the central nervoussystem (CNS). Both tetrapeptide(s) and hepta-peptide(s) were detected by RIA in the CNS andkidneys. Hyperosmotic treatments of animals, andthe in vitro treatments of CNS or kidney withserotonin results in increased levels of FaRPs inthese tissues. Serotonin and FaRPs are likely to beinvolved in osmoregulation in these animals.

STIMULATION OF ECDYSTERO1DOGENESIS BYSMALL PROTHORACICOTROPIC HORMONE: ROLEOF CALCIUM. G. C. Hayes and R. D. Watson*.University of Alabama al Birmingham.

Insect prolhoracic glands nrc rcgiilnlcd by nciiropcplidcprollioracicolropic hormones (PITH). In the tobaccohornwortn, Manducn sexta. PITH exists as two sizevariants, big FTTH (~ 25.5 kDa) and small PTTH (- 7kDa). Previous studies indicate that both size variantsemploy cAMP as a second messenger and that stimulationof ccdystcroidogcncsis by big PTTH is calcium-dcpcndcnl.In the present study, prolhoracic glands were dissectedfrom Nl scxta larvae on Day 3 of the last larval stadiumand incubated in vitro in the presence of agents selected toperturb intraccllular calcium ICNCIS; the effect of theagents on ecdysteroid secretion was determined byradioimmunoassay. Basal ccdyslcroidogcncsis was notalTcclcd by calcium channel blockcrs (vcrapnmil orlanthanum) or by omission of calcium from the incubationmedium. Treatment of glands with a calcium ionophorc(A23187) produced a dosc-dcpcndcnt stimulation ofecdjslcroidogcncsis. Finally, the stimulation ofccdyslcroidogcncsis by small PTTH was inhibited (1) bycalcium channel blockcrs and (2) in calcium-freeincubation medium. The results indicate that basalccdystcroidogcncsis is not calcium-dcpcndcnl and suggestthat small PTTH-stimulalcd ccdys'.croidogcncsis ismediated by an influx nrc.ilv.ium.


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MOBILIZATION OF MINERAL BYEMBRYOS OF A FROG WITH DIRECTDEVELOPMENT, ELEUTHERODACTYLUSCOQUI. M.J. Packard*, D.H. Jennings, J.Hanken and G.C. Packard. Colorado StateUniv., Ft. Collins and Univ. Colorado, Boulder.

Whole eggs or yolks and embryos of E. coquiwere analyzed for Ca, Mg, and P at differentstages of development. Fresh eggs containedabout 40, 20, and 100 jtg of Ca, Mg, and P,respectively. Most Ca, Mg, and P in fresh eggsoccurred in the yolk, but the jelly layers alsocontained small quantities of these elements.Embryos accumulated Ca and Mg slowly atearly stages of development and more rapidly atadvanced stages. However, P accumulation didnot follow a regular pattern. Embryos mobilizedabout 68% of the Ca available from yolk andabout 50% of the Mg and P. Residual yolk is aproportionately richer source of nutrients forneonates than is the case for neonates ofoviparous amniotes. (Supported by NSF:IBN-8718191 & 9407136 to MJP; DCB-9019624& IBN-9321572 to JH.)

C O N S U M P T I O N O F N I C O T I N E BY ATOBACCO FEEDING INSECT IS MEDIATEDB Y INDUCTION OF DETOXIFICATIONENZYME ACTIVITY. M.J. Snydcr*. and J.I.Glcndinning. Univ. of Arizona, Tucson.

Larvae of the tobacco hornworm arc relativespecialist feeders on solanaccous plants includingtobacco. We used two approaches to study theinteractions between hornworm feeding andJetoxification. We first investigated the time coursecorrelation of detoxification enzyme induction withchanges in feeding behavior. When naive last inslarlarvae were fed an artificial diet containing nicotine,feeding decreased in a dose-dependent manner.Within the next 32 hours of feeding on a highnicotine diet, feeding rates increased to normallevels. The resumption of normal feeding wasaccompanied by increases in cytochromc P450mediated nicot ine metabol ism by midgutmicrosomes. The second approach was to inhibitdetoxification enzyme activity and examine its effecton subsequent feeding behavior. When nicotineprc-cxposcd larvae were fed nicotine diets plusadded P450 inhibitor, both subsequent feeding andmidgut P450 nicotine metabolism were significantlyreduced to naive levels. These results show thatfeeding by this specialist insect herbivore appears tobe regulated by the degree of midgut detoxificationactivity towards one of the major plant defensivechemicals.

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PYYRUVATE-AMINO ACID OXIDOREDUCTASES INLINGULA REEVI. C.S. Hammen * and J.B.Morrill. New College, Sarasota, FL

Extracts of tissues of Linqula reevifrom Kancohe, Hawaii, were effective incatalyzing the reductive condensationof pyruvate with each of four aminoacids (the "opine" oxidoreductasereactions, EC 1.5.1 — ) . The reactionwith added taunne was most rapid, at6.61 micromol/min per g, or 69.8 percent of the sum of 'all activitiesmeasured. Activities with alanine,arginine, and beta-alanine were 6.3,12.1 and 10.8 per cent of the total,respectively. Oxidation of NADH withpyruvate alone was slow, and reversalof this reaction confirmed specifityfor L-lactate. The distribution ofthese activities was similar to thatfound in the smaller lingulid Glottidiapyramidata, reported by Hammen &Bullock in 1991. When these activitieswere coded and entered into thephylogeny program PAUP 3.1.1, Lingulaappeared at the base of the brachiopodclade.

CYTOCHROME P450 IN ANTARCTIC FISH:ENVIRONMENTALINDUCTION AND PROPERTIESOF THE (DIOXIN-INDUCIBLE) CYP1A ANDCONSTITUTIVE EXPRESSION OF CYP3APROTEINS.J. Stegeman, M. Oleksiak, B. Woodin and C. Dimare.Woods Hole Oceanog. Inst., Woods Hole.

Cytochromes P450 are membrane boundenzymes that synthesize and degrade steroids, andoxidize carcinogens, drugs and pollutants. Catalyticproperties, immuno-cross-reactivities and gene sequencesshow multiple P4S0 families in fish. Expression of thesewas examined in liver of four species from Antarcticwaters. High levels of hydrocarbon-inducible CYP1Awere seen only in N. coriiceps from near the BahiaParaiso oil spill. CYP1A was at most weakly detectablein D. mawsoni, P. borchgrevinki or C. gibberfrons fromelsewhere. Catalytic activity of CYP1A had anunusually high (-20°) temperature optimum. CYP2Bwas weakly or not detectable in any sample.Appreciable content of CYP3A homolog was seen in allfour species. The data indicate that Antarctic fishes havean Ah-receptor-mediated induction of CYP1A and thatCYP3A forms have endogenous functions, associatedwith constitutive expression like that seen in temperatespecies. PCR amplification and sequencing of genomicDNA further establishes the identity of the inducibleCYP1A in N. coriiceps. (NSF-OPP-9219418)

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LIPOAMIDE DEHYDROGENASES(LpDH) FROM RIBBED MUSSELGILL MITOCHONDRIAL EXTRACTSJ. Gallup and S. H. Bishop*. Iowa StateUniv., Ames.

LpDH catalyzes the oxidation ofthe disulfhydryl of lipoamide to thedisulfide. Differential centrifugation, heattreatment and chromatography onhydroxyapatite of gill mitochondrialextracts indicated two forms (sA.sB) inthe high speed supernatant and one (pC)in the high speed pellet. All were specificfor NAD/NADH and had similar Kms-Vm a xs with substrates; none showedNAD-NADP transhydrogenase activity.pC appears to be reversibly bound as acomponent of the high MW a-ketoaciddehydrogenase and glycine oxidasecomplexes and may be identical to thedissociated (unbound) sB form. Althoughthe role of sA is uncertain, it may functionas a diaphorase.

ESTIMATION OF SODIUM/PROTONANT1PORTER mRNA IN MARINEINVERTEBRATES USING QUANTITATIVERT-PCR.D.W. Towle, M.K. Jordan and D.W. Shearer.Mount Desert Island Biol. Lab., Salsbury Cove,ME and Lake Forest College, IL.

Our determination of the complete cDNAsequence of a sodium/proton antiporter from thegreen crab Carcinus macnas has enabled theconstruction of degenerate and specific primersfor amplification of antiporter sequences from avariety of marine and euryhaline invertebrates.We have used quantitative reverse transcription-polymerase chain reaction (RT-PCR) to estimatesodium/proton antiporter mRNA in gills ofCarcinus. Antiporter mRNA appears lo besomewhat more prevalent in the posterior gills ofcrabs acclimated to low salinity in comparison toanterior gills or in comparison to gills of animalsacclimated to high salinity, but is expressedstrongly under all conditions. In contrast,antiporter mRNA expression is much reduced inmuscle. Using degenerate PCR primers, a widevariety of marine invertebrates were shown topossess a related sodium/proton antiporter.Supported by NSF-RUI (IBN-9407261), EPSCoR,and American Heart Association.

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THE EFFECTS OF NEUROHORMONES ONCARDIAC ELECTRICAL AND MECHANICALPROPERTIES IN THE SHORE CRAB CARCINUSMAENAS.M.A. Saver* and J.L. Wilkens. Univ. of Calgary,Canada.

The effects of amine and peptideneurohormones on cardiac electrical activity andforce were tested in crab hearts in vivo and in vitro.Cardiac ganglion (CG) electrical activity, measuredby extra- and intracellular electromyograms(EMGs), was correlated to myocardial force(intraventricular pressure or isometric tension).Neurohormones were perfused directly into thehearts at concentrations of I0-8M to 10-5M for 30seconds. In vivo, the peptides proctolin andcrustacean cardioactive peptide (CCAP) producedfast, transient increases in contraction rate andforce. The amines octopamine, dopamine andserotonin (5-HT) produced slow onset andprolonged increases in contraction rate and force. Inboth intact and isolated hearts, EMG predictedmyocardial force for all neurohormones exceptproctolin. Proctolin caused disproportionateincreases in force relative to EMG activity,suggesting direct action at the myocardium.

IONIC AND OSMOTIC GRADIENT EFFECTS ONTRANSEPITHELIAL TRANSPORT IN THE FOOT OFTHE TERRESTRIAL SLUG, UMAX MAXIMUS.J.C. Fleming*. B.T. Fcnlon and I.G. Wclsford BradleyUniv., Pcoria, IL.

Short circtiil current (!„,) was recorded across Ilic footof the terrestrial slug, Umax maxwws, using a modifiedUssing chamber. Inward I* averaged 65.2 •*/- 7 6uA/cm : and exhibited a linear I/V relationship betweenIhc holding potentials of -100 (o +100 mV Ionsubstitution experiments indicated that Nn' is theprimary ion conducted. There was a 13 + 2.4 %decrease in Isc when I |iM amiloridc was applied lo theoutside surface or the Tool but no decrease whenamiloridc was applied to the inside fool surface Varyingionic and osmotic concentration gradients were appliedacross the fool lo determine sensitivity of 1K to thesevariables. The gradients used were equivalent lo thosethat exist across the foot in a dehydrated animal. Bothhypcrionic and hypcrosmolic (with normal ionicconcentrations) gradients caused a significant increase inU, suggesting that fool epithelial transporters arcresponsive to both variables in the intact animal.Increased ionic transport may thus be used as a means fora rchydraling slug to maintain osmotic gradients forparaccllular water uptake through Ihc foot during contactrchydration.

Supported in part by the Whitehall Foundation, OTEFDat Bradley and a Burroughs-Wcllcomc Fellowshipthrough the MD1BL.

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NERVE-NET INTERACTIONS FORMODULATING BEHAVIOR IN ASCYPHOMEDUSAN COELENTERATE.L.M. Passano.* Univ. of Wisconsin Madison.

The eclodermal nervous system of scypho-zoan jellyfish consists of two separate and distinctnerve-nets connected only at the marginal rhopali-a. The faster through conducting "giant fibernerve-net" (GFNN) conducts a nerve impulsefrom the lead rhopalium to the striated subumbrel-lar muscles used in producing the swimming jet.The other, the "diffuse nerve-net" (DNN) is lessrestricted in its extent; in rhizostomes it extendsthroughout the subumbrellar and manubrialtissues. In previous analyses of jellyfishncuroelhology the DNN has been assumed to haveprimarily a sensory role to the GFNN's motorfunctions.

Through a novel experimental approach itis shown that the DNN of Cassiopea xamachanaplays a major role in modulating the endogenousactivity of the rhopalial centers to produceoccasional bursts of enhanced swimmingcontractions, a major component of the long-termbehavior of this semi-sessilejellyfish.

Sensory hairs on insect antennae arc theprimary location for the interception ofchemical signal molecules by the insect fromthe surrounding air (such as phcromoncs).The insect obtains information about itsenvironment from the rate of interception ofthese molecules. Although intuition mightsuggest that the rale of interception ofchemical signal molecules by an antennashould increase with air speed relative to theantenna, fluid mechanical principles predictthat this may not be the case for slower airspeeds (< 1 mis). These slower air speeds,which result in low Reynolds number flowthrough the antennae, are biologically relevantfor many insects, including the domesticsilkworm moth (Bombyx mori). Theindependence of capture rate from air speed inslowly moving air was verified empirically byestimating mass transfer coefficients fromnaphthalene sublimation rates using scalcd-upphysical models of male liomhyx moriantennae. This approach allows the generationof null hypotheses for rales of phcromoncinterception by antennae based solely onphysical principles.

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THERMOREGULATION IN THE YELLOWJACKETSVESPULA MACULIFRONS AND Vj_ GERMANICA.J.R. Coelho* and A.J. Ross. WesternIllinois Univ.

In both species of wasps, heat(T.) and thorax (T .) temperatureof workers returning to the colonywere elevated above ambient temperature(T ). The gradient between T . andT adecreased as T increased, whiletne percentage of workers regurgitatingincreased from 0% at 15°C to 40%at 31°C. In V_. maculifrons T andT were constant from 27 to 35 CT . Heating the head of restrainedanimals resulted in regurgitationin >86% of individuals. A smallamount of fluid was produced ata Th of ~39°C, and seemed to stabilizeT. . A large droplet of fluid wasregurgitated at a T of~43°C, resultingin a~4°C reduction in T. when thedroplet spread over the Read. Smallregurgitations might be used routinelyfor evaporative cooling, while largeones could help avert lethal Tat high T . Regurgitation as anindividua? thermoregulatory strategymay have evolved from preexistingsocial behaviors in Vespula andApis, such as colony theraoregulationand foraging for fluids.

THERMAL AND MDH PHENOTYPEEFFECTS ON FLIGHT METABOLISM INHONEY BEES.J. F. Harrison*, D.I. Nielsen, and R.E. Page,Jr. Arizona State Univ., Tempe and Univ.of California, Davis.

The fast and medium allozymes of malatedehydrogenase (MDH) exhibit clines onthree continents in honey bees, suggestingthat thermal effects on MDH may havefunctional consequences. For honey bees inhigh intensity flight, as ambienttemperature (Ta) increased from 20°C-40°C,flight metabolic rate (MR) decreased by 40%and wing-beat frequency (WBF) decreasedby 15%. The decrease in MR occurred asthorax temperatures (Tu,) rose from 38°C to45°C, suggesting that either bees reducedMR to prevent over-heating, or that highTu, directly surpressed MR. We tested forwithin-colony effects of MDH phenotype onworker bees which were, on average, 75%related. We found differences in flight MRand WBF between bees differing in MDHphenotype, suggesting that selection mayact on MDH phenotypes in honey bees viaan effect on flight performance.

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414 415

TEMPERATURE EFFECTS ON TETHEREDFLIGHT ENERGETICS OF DROSOPMLAHYDEI.B. Joos* and J.R.B. Lighton. Univ. of Utah,Salt Lake City.

Female D. hydei were tethered to a fine wireand suspended in a flow-through rcspirometcr.Flight was initiated by a sharp transient in-crease in air flow. Carbon dioxide production(VCO2) and wingstroke frequency were re-corded continuously. Metabolic rates of inac-tive flies increased with increasing temperature(Q,o ca. 2). Body mass and temperatureaccounted for >60% of the variation in inac-tive metabolic rate. Wingstroke frequency in-creased with increasing temperature (r*=0.16,P=0.002) but the change in frequency wassmall. Metabolic rates during flight wereindependent of temperature and were 8-25 foldgreater than those of inactive flies. Metabolicrates during flight were correlated with wing-stroke frequency (r== 0.33, P<0.001). Mass-specific energy input per wingstroke wasindependent of either temperature or bodymass. These results suggest that resonancemechanisms and elastic storage may be impor-tant even in very small insects.

PARTITIONING RESPIRATORY AND CUTANEOUSEVAPORATIVE WATER LOSS AT HIGHTEMPERATURES IN A SMALL BIRD.B. O. Woll* and G. E. Walsberg. Dept. ol Zoology.Arizona Stale Univ. Tempe.

Current data indicates that at moderatetemperatures (25 !o 35 °C) evaporative water loss inbirds is partitioned almost evenly between cutaneousand respiratory components. High temperature data fora very limited number ol species suggests thatpartitioning ol water loss may follow two differentpatterns, depending primarily on either cutaneous orrespiratory modes ol heat transfer. We measured ratesof pulmonary and cutaneous evaporative water loss asa function of air temperature in a small desert bird, theVerdin, Auriparus llaviceps. Birds were placed in a twocompartment metabolic chamber that separated waterloss from the bird's head and body. CO2 production,cutaneous, and respiratory evaporative water loss forresting birds was measured every two degrees between30 and 50 °C. Cutaneous water loss increased from3.3 -10.3 mg g - 1 h r 1 from 30 to 50 °C and accountedfor 61 and 14 % respectively, of total evaporative wateiloss. Respiratory water loss ranged from 2.1 to 64.1mg g ' 1 hr'1 from 30 to 50 °C. At moderate airtemperatures water loss was partitioned almost evenlybetween respiratory and cutaneous components, but asair temperature was increased Verdins became heavilydependent on respiratory evaporation for heatdissipation. At 50 °C, respiratory evaporative heat lossequaled 150% of metabolic heat production versus 25%for cutaneous heat loss. These data differ significantlyfrom most available data which indicate that cutaneouswater loss is the primary mode ol heat transfer at hightemperatures.

416 417

THE BASIS FOR COLD-TOLERANCE INIIATCIILING PAINTED TURTLES.G.C. Packard* and M.J. Packard.Colorado State Univ., Fort Collins.

Hatchling painted turtles (Chrysemys picta)usually spend their first winter of life insidethe shallow, subterranean nests whereembryogenesis was completed the precedingsummer. Although temperatures in nests atnortherly localities may decline in winter tominima as low as -lOoC, many hatchlingswithstand the exposure. This ability to survive inthe cold has been widely attributed to atolerance by turtles for freezing of water in theextracellular space. We find, however, thatfreezing is invariably fatal and that survival inthe cold depends on animals remainingunfrozen. Turtles do not produce antifreeze,so the adaptive strategy for overwintering byhatchlings is based on their ability to sustaina state of supercooling.

THERMAL ECOLOGY AND METABOLICPHYSIOIXDGY OF HIGH ELEVATIONNEOTROPICAL ANURANS.C. A. Navas, Univ. of Connecticut

The thcrniiil ecology and the metabolic physiol-ogy of three high elevation anurous in theColombian Andes (Coloslclhus subpunctalus.Eleuiherodactylus bogo/cruis, and Hyla lubiiilix)were analyzed for correlates with life in an extremeand variable environment. 1 compared populationsat 3500 m and 2900111, collecting data 011 fieldtemperatures, thermal sensitivity of resting and ac-tivity metabolism, capacity for metabolic acclima-tion, and the effects of temperature on burst loco-motor performance. E. bof-olensii,a nocturnal andterrestrial species, is active at low temperatures, butthe other species arc cither diurnal or aquatic, andconsequently experience more moderate activitytemperatures. All three species exhibited a distinc-tive capacity for locomotion through a broad tem-perature range, and E. bogotensis showed an up-ward translation of the metabolism versus temperature curve for the high elevation population.However none of the three species exhibited a ca-pacity for metabolic acclimation. Success at hightropical elevations appears to involve complex in-teractions among metabolic physiology, behavior,and habitat selection, that vary from species tospecies. The uniqueness of these interactions willbe tested by comparative analysis with lowlandforms. Work supported by the Banco tie la Rcpii-hiica. Colombia, :mu the Hi' nrogram of I'.NC.

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Ecology

418 419INTRASPECIFIC VARIATION IN GAMETEQUALITIES INFLUENCE IN SITU LEVELS OFFERTILIZATION SUCCESS IN THE ECHINOIDSTRONGYLOCENTROTUS FRANC1SCANUS.D.R. Levitan. Florida State Univ., Tallahassee.

Variation in the percent of eggs fertilized in free-spawning taxa has previously been attributed tofactors that influence local sperm concentration. Inthis study, samples of eggs and sperm were testedsimultaneously in the laboratory and field todetermine if intraspecific variation in gamete qualityinfluences field rates of fertilization. In thelaboratory, eggs were fertilized in one of seven serialdilutions of sperm. Off the west coast of VancouverIsland, British Columbia, Canada, sperm were mixedwith dye and released into the ocean. Eggs werereleased into the sperm cloud at one of six timeperiods (2.5 - 80 s). After 120 s, eggs wererecollected with a plankton pump. A complete trialutilized the eggs and sperm from a single pair of seaurchins over all seven sperm dilutions in thelaboratory, and all six time periods in the Held.Laboratory rates of fertilization explained over 50%of the variation in fertilization success seen in thefield. Variation in laboratory fertilization rates areattributed to egg size and sperm quality. Theseresults suggest that gamete attributes arc importantdeterminants of fertilization success and that selectionon gametes for enhanced rates of fertilization will notbe swamped by environmental factors.

UNDERSTANDING MARINE B I O D I V U O I T Y : ANATIONAL RESEARCH AGENDA. C.A. Butmanand J.T. Carlton*, Woods Hole Oceanographic Inst.,MA and Williams College-Mystic Seaport, Mystic CT.

A research agenda on marine biodiversity (BioMar)has been proposed in a report of the National ResearchCouncil. Marine diversity has been or could hedramatically altered by a spectrum of human activities,including fisheries operations, chemical pollution andeutrophication, physical habitat alterations, invasionsof exotic species and global climate change. Evaluatingthe scale and consequences of these activities, andunderstanding mechanisms responsible for the creationand regulation of diversity, are, however, seriouslycompromised by critically inadequate knowledge of thepatterns of and the processes that control marinebiodiversity. BioMar incorporates a fundamentalchange in the approach by which biodiversity isstudied by emphasizing integrated regional-scaleresearch (utilizing multiple, separate sites within alarge geographic region) in an environmentallyrelevant framework. Critical agenda componentsinclude advancing taxonomic expertise, developinginterfaces between ecology and oceanography, andbcrwecn ccolng) ami u\onomy. ami ininrrnnanngncwadvances in insliuincnlaliim. cxpci imcntal lci'liuit|ik'N.and molecular genetics. An improved understanding ofdiversity will facilitate predictions of future impacts ofhuman activities on the ocean, with a goal ofdeveloping policies to minimize such c fleets.

420 421PARENTAGE DETERMINATION OF LARVAE

FROM A CARIBBEAN GORGONIAN.

M.A.Coffroth. State University of New York at

Buffalo. Introduced by C.A. Loretz.

The determination of parent-offspring

relationships is critical for discerning mating

systems, measuring reproductive success, and

interpretating population dynamics. I have used

the polymerase chain reaction (PCR) to generate

randomly amplified polymorphic DNA (RAPDs)

markers for individual genotypes of the gorgonian

Plexaura kuna. Mendelian inheritance of RAPD

markers was confirmed through a series of

breeding experiments and parental markers were

identified in each offspring. Markers were

characterized as to whether they were

heterozygous or homozygous. Knowing whether

the genotypic-specific markers are heterozygous

or homozygous can allow parental identification

by inclusion using single or a few markers and

thus reduce the number of loci that are necessary

for parentage analysis. I am now using RAPD

markers to establish parentage of Plexaura kuna

larvae collected in the field during spawning.

These data will be used to determine the factors

controlling fertilization success in this clonal

marine invertebrate.

FRAGMENTATION IN THE GORGONIAN CORALPLEXAURA SPECIES A: COSTS TO SEXUALREPRODUCTIVE OUTPUT AND COMPUTER SIMULA-TIONS OF LONG-TERM CONSEQUENCEST. M. McGovern. F l o r i d a S t a t e U n i v e r s i t y

Fragmentat ion a s a mode of a s e x u a lpropagat ion i s common in a number ofmarine i n v e r t e b r a t e s . Fragmentat ion maybe viewed as an injury or, alternatively,as a method of spreading the risk ofgenet mortality and potentially increas-ing lifetime genet reproductive output.Fragmentation exerts a short-term cost tothe sexual reproductive capabilities ofboth ramets and genets of the gorgoniancoral Plexaura species A. Computer simu-lations comparing the lifetime reproduc-tive outputs of fragmenting and non-fragmenting genets suggest however thatthe costs are short-lived and thatfragmentation can produce a net gain infecundity within a reasonable amount oftime. The prediction of an increase inlifetime fecundity coupled with morpho-logical features that actively facilitatefragmentation indicate that fragmentationmay be adaptive in this organism.

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Ecology

422 423WHAT DO SPONGES HAT QUANTIFICATIONOF SPONGE SUSPENSION FEEDING USINGDUAL BEAM FLOW CYTOMETRY.AJ . Pile* and M R Patterson. The College ofWilliam and Mary, Virginia Institute of MarineScience, Gloucester I'oint, VA 23062.

Using dual beam flow cytomctry wequantified suspension feeding of both fresh waterand marine sponges on picoplankton. Watersamples taken adjacent to sponges and from spongeexhalent currents were analyzed for heterotrophicand autotrophic picoplankton. While all of thesponges studied significantly affected all types ofpicoplankton, fresh water globose sponges demon-strated significantly higher feeding efficiencies thanencrusting sponges, removing as much as 96% ofsome types of picoplankton from the water theyfiltered. However, encrusting sponges from LakeBaikal significantly increased both heterotrophicbacteria and autotrophic picoplankton with onechloroplast suggesting that they may be provide asuitable substrate for these organisms We con-servatively estimate 1 m2 of bottom covered withsponges at natural densities in Lake Baikal canconsume 0.900 g of carbon per day. Given theparticle size distribution in these systems, pico-plankton may be an excellent source of carbon forsponges.

MICROHABITAT FACTORS AND THE DISTRIBUTIONOF MOTILE EPIZOITES ON Montastreaannularis.Runnels, R.J. Texas ASM University,College Station.

Quantitative studies of invertebrateepizoites on corals and similar marineorganisms have necessitated the removaland destruction of the living substrate.We have applied methods similar to thoseused in terrestrial studies of epiphyticinvertebrates to the study of small-scalespatial patterns of copepods, mites andother organisms found on the surfaces ofthe coral Montastrea annularis. Thesemethods are nondestructive to the hostcoral, and they require small numbers ofepizoites. The abundances of a variety ofepizoite species, particularly parasites,were correlated with light and flowregimes near the coral surfaces. Inaddition, l ight differences resulted intemperature microclimates at the coralsurface. Present and planned work i saimed a t establishing cause/effectrelationships through manipulativeexperiments in the laboratory and field.We are also considering the possibleselective advantages of the observeddistributional patterns. Terrestrialanalogues may provide some insight intomarine epizoite ecology.

424EFFECTS OF FIDDLER CRAB FORAGINGON A BENTHIC SANDFLATCOMMUNITY.K. Reinsel. Duke University MarineLaboratory, Beaufort, NC.

Over 10 million sand fiddler crabs Ucapugilalor forage on the top 5 mm of a 0.2 km2

sandflat during each tidal cycle. I hypothesizedthat this daily reworking of the sedimentsurface should have an impact on the benthiccommunity. I used a series of exclusion cagesto determine the effects of fiddler crab foragingover a 9 month period. Dramatic effects ofexclusion occurred within the first 2 months.In the absence of crabs: 1) Macrofaunaldensity doubled; 2) Sediment organic andchlorophyll a contents doubled; 3) Meiofaunaldensity doubled after 2 weeks. Exclusioneffects were less dramatic from 2 weeks to 4months of exclusion, and absent thereafter.Seasonal changes in abundance of fiddlercrabs, coupled with high densities of the mudsnail llyaiiassa obsolete in exclosures probablycaused the change in magnitude of the fiddlercrab effect. Uca pugilator foraging regulatesthe community in this system. The specificeffects and degree of impact vary seasonally.Supported by a Grant-in-Aid of Research fromSigma Xi.

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History & Philosophy of Biology

Morphological and Evolutionary Explanation:An Reply to Bock and Dullemcijer. J. ToddSlrcclman, University of South Florida, Department ofBiology. Tampa, FL 33620-5150

Bock and Dullemeijer claim that there aretwo types of explanations in morphology.Functional explanations are deductiveformulations of structural operation,form/function correlation and the adaptednessof features. Evolutionary explanations arehistorical interpretations of character origin.Functional explanations are taken to besuperior because of their basis in deduction. Iargue that (1) Bock and Dullemeijer havemisappropriated the concept of "deduction"from Hempel; that subsequently they have (2)confounded the concepts of "explanation" and"prediction"; and finally that (3) there is noUSEFUL functional/evolutionary distinction.My argument consists of (a) an analysis ofexplanation/prediction andinduction/deduction, (b) an examination ofmorphological problems, and (c) a discussionof morphology in the context of historicalbiology.

425

ABSTRACTS 89A

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426 427ANATOMY OF THE BOWHEAD WHALELARYNX.Schoenfuss, H. L.* and D. J. Hillmann. LouisianaState University.

Little is known about the internal anatomyof the "Right Whales". For this study, the larynx

of the Bowhead Whale Balaena mysticelus wasinvestigated. Four embalmed fetuses were dissected:1 in situ, 2 isolated larynges, and 1 in cross-section.Compared to the larynx of terrestial mammals, it

was expected to find significant differences in theanatomy of the Bowhead Whale larynx. TheBowhead Whale larynx extended into the thoracicinlet and was positioned more caudally than interrestial mammals due to the shortened cervicalregion. The four laryngeal cartilages were greatlymodified. The thyroid cartilage was missing a cranialcornu and the cricoid cartilage was partially fusedwith the tracheal rings. The tracheal rings werecomplete and formed a dorsally flexed cartilaginoustube with that of the larynx. An extensive laryngealdiverticulum was positioned ventral and caudal tothe laryngeal vestibule. The diverticulum, surroundedby strong dorsal and ventral musculature, was flankedby the caudal cornu of the arylenoid cartilage. Novocal folds were observed. The small diameteresophagus showed little ability for dilation. Furtherstudies as well as investigations on fresh tissue willbe necessary to evaluate the structural differencesof the Bowhead Whale larynx.

HYDRODYNAMIC DESIGN OF THEHUMPBACK WHALE FLIPPERF.E. Fish* and J.M. Battle, West Chester Univ.,PA.

The morphology of a 2.5 m flipper from ahumpback whale (Megaplera novaeangliae) wasevaluated with regard to hydrodynamic design.The flipper had a wing like, high aspect ratioplanform. Rounded tubercles were regularlyspaced along the flipper's leading edge. Theflipper was cut into 2.5 cm cross-sections andphotographed. Except at the lip, cross-sectionswere symmetrical with no camber. Sections hada blunt, rounded leading edge and highly taperedtrailing edge. Placement of maximum thicknessvaried from 49% of flipper chord at the tip to19% at mid-span. Maximum thickness/chordaveraged 0.23 with a range of 0.20-0.28. Cross-sectional design is typical of manufactured foils.Leading edge tubercles appear analogous toenhanced lift devices to control flow over theflipper. Cross-sectional design and leading edgetubercles of the flipper indicate gentle stallcharacteristics with maintenance ofhydrodynamic lift at high angles of attack. Theflipper's morphology suggests an adaptation forhigh maneuverability associated with thehumpback whale's unique feeding behavior.

428 429

TRABECULAR FUNCTION DURINGERECTION OF THE CORPUSCAVERNOSUM IN THE NINE-BANDEDARMADILLO (Dasypiis novemcinctus).D. A. Kelly. Duke University, Durham, NC.

The tissue responsible for penile erection inmammals is contained in a single structure,the corpus cavemosum. This structurecontains an irregularly shaped blood-filledspace crossed dorsoventrally by collagenoustrabeculae. Artificial inflation of armadillocorpora with normal and cut trabeculae wasperformed in order to determine trabecularfunction in erection. Comparison of strainsin the corpora wall showed that trabeculaerestrict dorsoventral expansion of the corpuscavemosum during erection. Comparison ofinternal pressure readings showed that at anygiven volume, pressure is lower in corporawith cut trabeculae. In conjunction, thesedata imply that the trabeculae increase theinternal pressure of the structure byrestricting dorsoventral expansion of thecorpora wall during erection. This may berelated to increased stiffness of the penisduring erection.

CRANIOFACIAL HETEROCHRONY ANDALLOMETRY IN MUSCULAR DYSTROPHIC MICE.P. Lightfoot, Univ. of Cincinnati, Cincinnati, Ohio.

This study examined the influences of epigeneticfactors on skeletal development using musculardystrophic mice as a model system. Because of thehighly interrelated nature of the muscular and skeletalsystems, the degeneration of muscle tissue with theprogression of the disease significantly affects thegrowth of various skeletal elements. Specifically, thisstudy examined the allometric and heterochronicchanges that occurred in dystrophic individuals usinglongitudinal radiographs Radiographs were taken atvarious frequencies determined by age and growthrate and were continued for at least 250 daysMeasurements of various skull lengths and widthswere constructed using biologically relevant andhomologous points. Parameters from nonlinearGompertz models were tested for differences betweendystrophic and control individuals. For mostmeasurements, including weight, the dystrophic miceexhibited a smaller final size. The instantaneous ratesof growth were different for weight and the distancebetween the most anterior points of the zygomaticarches, and were marginally different for the length ofthe face as well as the distance between coronoidprocesses. The rates of exponential decay of growthwere different for the distance between the angles ofthe mandible and the distance between the bulla, andwere marginally different for weight, total skull length,length of the face, and the distance between thezygomatic arches. In conclusion, the musculardystrophic condition increases the variation in skeletalmeasurements by affecting different bones differently.

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430 431PATH OF STRAIN ACROSS THE SKULLS.W. Herring* and S. Teng. University ofWashington, Seattle.

Brief periods of unilateral activity often occurin jaw muscles. In anesthetized pigs, unilateralactivity of the masseter muscle causes bonestrain in the zygomatic arch, not only on theactive side, but also on the inactive side. Thusthe load must be transmitted across the skull.We investigated two possible paths oftransmission. First, compressive joint forces onthe active side may be transmitted across thebraincase. We recorded from rosette straingages on the frontal or parietal bones. Thedirection of strain in the bones of the braincasewas consistent with compression at the activejaw joint, and strains were transmitted efficientlyacross the midline. However, strain amplitudeswere lower than those in the inactive zygomaticarch. Thus this pathway cannot be the primaryone. Second, dislocating loads on the inactivejoint may be transmitted through its capsule.Partial cutting of the inactive side joint capsulediminished the transmitted zygomatic strain by50%. Therefore, dislocating loads on theinactive joint are the major pathway fortransmitted strain, and these loads aresupported in life by the joint capsule. Supportedby PHS DE08513.

VARIABILITY AND SIZE IN MAMMALS.B. Hallgrimsson* and V.C. Maiorana. Universityof Chicago, 1L, and Lothlorien Laboratory ofEvolutionary Biology, Chicago, IL.

Phenotypic variation is the raw material ofevolution. Surprisingly, there have been very fewsystematic studies of variability. Using the NMNHcollection database for mammals, we examinepatterns of interspecific variation in size-relativevariability in a sample of 65,074 individuals from351 species of mammals. We find that the size-relative variability of body mass and total bodylength displays a highly significant positiveassociation with mean body size at the specific,generic, and familial levels. This result is notexplained by bias due to measurement or data entryerror, technique, number of subspecies, agerepresentation, or phylogenetic variation invariability. Separate analyses by sex eliminate theeffect of sexual dimorphism. We also eliminatematurational spans, geographic distribution, homerange size, and population density as possibleexplanations for the increase in variability with size.One explanation that is not contradicted byavailable data is a tendency for smaller species tooccupy narrower niches.

Funded by Smithsonian and Alberta HeritageFund fellowships and the Hinds Fund to B.H..

432 433

FACTORS AFFECTING SURFACE-MASS RELATION-SHIP IN VERY LARGE ANIMALS.Stuart 0. Landry Jr., State University ofNew York, Binghamton.

The relationship between cross-section-al area and volume scales uniformly tothe 2/3 power but the relationship ofsurface area to volume depends upon theshape. For very large animals it is ad-vantageous to maximize the surface areacompared to mass. To estimate the degreeto which surface area has been maximizedin Apatosaurus I devised a "standard"tetrapod body: a cone of unit diameterand unit height; a cylinder of unit dia-meter and twice unit height; a cone ofunit diameter and twice unit height; andfour cylinders of 1/4 unit diameter and1/2 unit height. (Head, trunk, tail andlegs.) The surface area and volume ofApatosaurus was estimated from an illust-rationby breaking up the shape into reg-jlar geometric forms. The surface areaof the "standard" shape of the same vol-ume as that of the dinosaur was calculat-ed. The advantage that the dinosaur hasover the "standard" is about 93/83, butit gains an even greater advantage byshifting from a circular to an ellipticalcross section, a condition brought aboutby the greater weight to be supported.

HOW BIG FROGS GET SMALL: THERELATIONSHIP BETWEEN SIZE ANDSHAPE.D J. McinhardL University of Kansas, Lawrence.

Evolutionary morphologists consider size animportant parameter in the evolution of novelmorphologies. Phylclic size decrease(miniaturization) has been invoked lo explain theorigins of body plans in several groups oforganisms. Workers have made numerousgeneralizations regarding the morphology ofdwarfed species because convergence is commonamong these taxa. Anurans (frogs and toads) arca group in which small size has evolved severaltimes; thus, they arc an excellent taxon for thestudy of miniaturization. Characteristics of (hecrania of numerous anuran laxa were quantifiedand plotted in an attempt to discover convergentpatterns among miniaturized species. Variationin skull shape (as measured by head length vs.head width) is almost entirely size-determined.The unique skull morphology of NorthAmerica's smallest frog (Pscudacris ocularis) iscompared lo that of other anurans, and discussedwith regard lo predictions made by other workersconcerning the morphology of dwarf laxa. Ipropose lo alter experimentally variousdevelopmental parameters (related to size) loelucidate how such shifts might effectmorphological diversification.

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434 435

HOW S N A K E S K U L L S S H R I N K AND G R O W :

O N T O G E N Y , A L L O M E T R Y AND P H Y L O G E N Y .

W . A . V e l h a g e n , J r . D u k e U n i v e r s i t y .

S m a l l b o d y s i z e e v o l v e d a t l e a s t

t w i c e w i t h i n t h e c o l u b r i d t r i b e

T h a m n o p h i i n i . U s i n g q u a l i t a t i v e a n d

q u a n t i t a t i v e d a t a , I c o m p a r e d

e m b r y o n i c g r o w t h a n d c r a n i a l

d e v e l o p m e n t a m o n g t h a t n n o p h i i n e a n d

o u t g r o u p s p e c i e s t o d e t e r m i n e t h e

2 f f e c t s o f s i z e r e d u c t i o n . R e l a t i v e

t o l a r g e s p e c i e s , s m a l l s p e c i e s

s h o w p a r a l l e l m o d i f i c a t i o n s i n

c r a n i a l m o r p h o l o g y a t b i r t h ; t h e s e

a r e a c c o m p a n i e d b y s i m i l a r c h a n g e s

i n d e v e l o p m e n t . T o e v a l u a t e t h e

r o l e o f s i z e i n p r o d u c i n g t h e s e

t r e n d s , I e x a m i n e d n e o n a t e s f o r

n a t u r a l v a r i a t i o n i n s i z e a n d

m a n i p u l a t e d e m b r y o n i c g r o w t h i n

s e l e c t e d s p e c i e s . R e s u l t s s h o w t h a t

s i z e i s c l o s e l y c o u p l e d w i t h

d e v e l o p m e n t n l s t a g e : o n e c o u l d n o t

b e c h a n g e d i n d e p e n d e n t l y o f t h e

o t h e r . T h i s L e a v e s t h e r o l e o f s i z e

i n c o n s t r a i n i n g m o r p h o l o g y i n t h e s e

s p e c i e s u n r e s o l v e d a n d p o i n t s o u t

t h e n e e d t o e x a m i n e d e v e l o p m e n t a l

s t a t u s i n s t u d i e s t h a t i n v o l v e

a l l o m e t r i c e n g i n e e r i n g .

BRONTOTHERE HORN ALLOMETRY AND THEINFERENCE OF HETEROCHRON1C PROCESSES.L.T. Holbrook*, L.R. Godfrey, and B.J. Mader.Univ. of Massachusetts, Amherst and theAmerican Museum of Natural History, NewYork, NY.

Relative growth of the horns ofbrontotheres has provided a classic exampleof both allometric and developmentalconstraints on evolutionary change. Whileprevious workers have made much progressin approaching this phenomenon, inferencesmade by some studies have been based oninadequate data or, more importantly, aflawed inference structure. A rcanalysis ofthe published data demonstrates that 1) theevidence lor the existence of separateallometric patterns fitting the "Eocene" and"Oligocene" forms is weak, and 2) it isincorrect to infer a change in onset limingfrom parallel allometrics in logarithmic space.Also, as shown by others, the allometricmodels that have been applied to these dataare not necessarily appropriate. Therefore,proper analysis of this subject will require,among oilier things, a more inclusive andmore accurate data set, the application ofmathematical models that are biologicallyappropriate, and an inference structure thatmore clearly considers the relationshipbetween allometry and hetcrochrony.

436 437

NEURAL TUBE FORMATION IN THE SEALAMPREY, PETROMYZONMAIUNUSD.M. Johnson. Univ. of Massachusetts, Amherst.

I undertook a new SEM study of early embryologyof lampreys in order to examine the development ofcritical anatomical characters such as sensory,pharyngcal, and neural tube formation. In this portionof the study, I report on aspects of ncurulation. Icollected eggs and milt of Pelromyzon marinws fromnatural spawning sites on the Fort River inMassachusetts and reared the embryos at I6°C-I9°C for24 days. A developmental scries was collected atclosely spaced intervals and preserved in 2.5%gluteraldehyde. There arc two generally acceptedapproaches in fishes to ncurulation: folding andcavitation. Teleosts and some other actinoptcrygianfishes cavitate whereas the majority of the other fishesappear to fold, with the exception of lampreys.Although lampreys show signs of folding externally, theresult is a solid neural rod. From this neural rod, theneural tube forms. The literature on this subject ismixed. Some researchers claim that a loosearrangement of cells in the neural rod suggests acavitation-likc approach to ncurulation. Others claimthat the lamprey merely folds without first forming acavity. Preliminary results suggest that folding initiallyproduces two columns of cells that neither mtcrdigitatc,nor form a cavity between themResearch funded* b> NSF grant BSR-y22fi«38.

ONTOGENY AND HOMOLOGY RECOGNITIONOF THE HYPURALS OF STURGEONS.E K. Findcis. University of Massachusetts, Amherst.

Hypurals arc dominant elements of the caudal fin ofactinoptcrygians, providing direct support for theIcpidotrichia and defining internal shape of the fin. Theyare defined positionally by forking of the caudal arteryposterior to the parhypural to flank the hypurals.Hypurals arc subjects of long-standing debate on theirhomology and have been serially homologizcd asmodified anal fin radials or haemal spines. I studiedontogeny of the caudal skeleton in the shovclnoscsturgeon Scaphirhynchus platorynchus to examinecaudal structure in a phylogcnctically primitiveactinoptcrygian. Hypurals arc the first vertebralelements to develop in sturgeons, appearing at 11.5 dayspost-fertilization as median, rectangular cartilagesventral to and contacting the notochord in the developingcaudal fin. In contrast, haemal spines develop muchlater, first appearing at 19.0 days post-fertilization aspaired elements that fuse and elongate. The parhypuraldevelops in series with and appears to be a haemal spinein origin. This distinction in developmental timing andinitial morphology docs not correspond to homologyrecognition of hypurals with cither anal fin radials orhaemal spines, and suggests that hypurals might be clenovo elements without serial homology. Caudaldevelopment of sturgeons implies that the caudal fin isdistinct from other fins in ontogeny and origin

Supported by NSF BSR-8901132


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COMPARISONS OF DEVELOPMENTALPATTERNS IN CLUPEOID FISHES.J. D. Shardo. University of Massachusetts, Amhcrst.

A detailed description of the ontogeny of Americanshad (Alosa sapidissima) from fertilization tometamorphosis is used as the basic pattern forcomparison. Shad development is described in 35stages using morphological features visible by SEM,LM and clearing and staining. To facilitatecomparisons, each stage is defined by only one or twomorphological criteria that arc fundamentaldevelopmental features of telcosts. Additionaldevelopmental events that occur concurrently arctreated as variables potentially uncoupled from thedefining criteria of the stage. Comparisons ofdevelopmental patterns among clupcoids indicate thatthe developmental stages defined for shad arcrepresentative of developmental patterns for clupcoidsduring the embryonic and yolk sac periods. In contrast,many concurrent features such as hatching and theformation of ncuromasts vary in developmental timingamong clupcoids. Shad hatch after the mouth opensduring development whereas most clupcoids hatchbefore the mouth opens. Regardless of stage athatching, clupcoids show a minimal level ofdevelopment of the lateral line system at hatching. Botrhatching and formation of ncuromasts demonstratehctcrochronic shifts in the development of clupcoidsSupported by NSF grant BSR-9220938.

THE EFFECTS OF GENOME SIZE ONDEVELOPMENTAL TIME IN PLETHODONTIDSALAMANDERSE.L. Jockusch, University of California, Berkeley.

Embryonic developmental time is affected by avariety of internal and external factors, includingtemperature, egg size, stage at hatching and possiblygenome size. Genome size is known to affect manyorganismal traits such as cell size, limb regeneration rate,and brain organization. Although a positive correlationbetween it and developmental time has beenhypothesized often, it has not been conclusivelydemonstrated in any taxon. In order to test thishypothesis, I examined the relationship amongdevelopmental time, egg size and genome size inplethodontid salamanders. Plethodontids provide a goodmodel system for this because genome sizes vary widely,developmental data are available for a diversity ofspecies, and phylogenetic relationships are wellestablished. Preliminary analyses on 14 species usingFelsenstein's (1985) method of independent contrastsreveal that increases in both genome size and egg sizeincrease developmental time. The relationship amongthese variables may constitute a constraint withimplications for life history evolution.

440 441

EARLY DEVELOPMENT OF THE CHONDRO-CRANIUM IN THE TAILED FROG(A5CAPHUS TRUEI).J . O . R e i s s . U n i v . of A r i z o n a ,T u c s o n .

C h o n d r o c r a n i a l d e v e l o p m e n t wasstudied in posthatching stages ofAscaphus truei ranging from 9 to18 mm TL. Graphical reconstruct-ions of selected stages were madefrom sectioned material. -Yolkgranules retained in mesodermalcel ls allowed them to be disting-uished from ectomesenchyma 1 (neu-ral crest derived) ce l l s . The pilapreoptica, anterior trabecula, andviscerocranium (except the secondbasibranchial) are ectomesenchymal.The basal (pseudobasal) processchondrifies in an ectomesenchyma1strand running from quadrate keelto basiotic lamina, behind thefacial foramen. Later, the basalprocess connects with the floor ofthe anterior cupula, creating sepa-rate foramina for the palatine andhyomandibular branches of the fac-ial nerve. These data allow reso-lution of the long controversialhomologies of palatoquadrate proc-esses between anurans and urodele

THE CONCEPT OF METAMORPHOSIS IN VIVIPAROUSVS. OVIPAROUS AMPHIBIANS. M. H. Wake,Univ. Ca l i forn ia , Berkeley.

Recent cons iderat ions of metamorphosishave considered i t ne i ther a process nor aphase of development, but as an a r b i t r a r i -ly recognized postembryonic per iod,usual ly shor t , in which a number of deve l -opmental events are concentrated. Thisobviates the need for e i t h e r mechanisticor ecological/life history criteria.

Among amphibians, most taxa are charac-terized by a distinct arid fairly abrupttransition that may encompass diversemorphological, ecological, endocrinologic-al, and l i fe history changes. Thesetypically occur as a transition from free-living larvae to juveniles. However,metamorphosis in direct-developing andespecially in live-bearing amphibians doesnot follow an ontogenetic trajectory simi-lar to that of related taxa with larvae."Larval" features may never appear duringontogeny, and the postembryonic develop-mental events that result in juveniles atbirth may be prolonged and disjunct. Aparticularly graphic example is that ofthe viviparous gymnophlone amphibians.Posthatching (intraoviductal) changes inskin, g i l l s , teeth, etc . , occur in a timescale dramatically different from that ofoviparous taxa.

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STRUCTURE OF THE YOLK SAC PLACENTADF THE MATROTROPHIC SCINCID LIZARDPSEUDEMOIA ENTRECASTEAUXII.J.R. Stewart* and M.B. Thompson.Univ. of Tulsa, OK and Univ. ofSydney, NSW, Australia.

The evolution of matrotrophyamong squamate reptiles results inreduction in egg size and greaterreliance on placental nutrientprovision. Placental reptilestypically have both an allanto-placenta and a yolk sac placenta.Allantoplacental specializationsare well documented for matro-trophic species, whereas fewerdetails are available for yolk sacplacentae. £. entrecasteauxii isa matrotrophic lizard in which theallantoplacenta and the yolk sacplacenta each contain distinctivestructural characteristics. Thedefinitive yolk sac placenta is anomphaloplacenta with a developmentand structure that are typical forSquamata. The timing ofdevelopment, epithelial cellhypertrophy, and extensive surfacearea of the omphaloplacentasuggest an important functionalrole in the pattern of embryonicnutrition in P. entrecasteauxii.

LIMB BONE SCALING IN FGF TRANSGENICMICE. R.S. Swisher* and R.Z. German. Univ.of Cincinnati, Ohio.

Mice transgenic for human fibroblastic growthhormone (FGF), an oncogene product, werestudied to see the effect of the transgene onbone growth and allometric scaling in limbbones. Infant mice obtained from breeding pairswere weighed and x-rayed initially 3 times perweek from birth to the age of 250 days, whenadult size was reached. Measurements ofmaximum length down the midline of the bonesand minimum widths were obtained for thehumerus, femur and tibia. Radius and ulnacould not be reliably measured. Ratios of lengtfto width were examined as a function of age totest for differences between the effected miceand normal controls. Scaling of the humerusand tibia were different between transgenic andcontrol mice, but not in the femur. Thetransgenic progeny had limbs, which wereshorter in length than controls, but notsignificantly different in width. The effectedindividuals limbs stopped growing in lengthsooner than the controls. There were nosignificant differences in weight between thetransgenics and the controls. This suggests thatFGF changes bone scaling by shortening limbs,but has no effect on total body mass.

444 445EPIGENETIC REGULATION OF CRANIALMORPHOLOGY IN THE PIG (SUS SCROFA).J.W. Helm. Univ. Cincinnati, Ohio.

Epigenesis is a process by which changes inmorphology are produced through environmental andinternal (non-genetic) stimuli. A number of studieshave demonstrated the ease of cranial alteration bythese environmental stimuli. Miniature pigs wereused as a model to investigate the influence ofmodifying one non-genetic factor. Previous work hasshown that rates of growth differ pre- to post-weaning. It is hypothesized that by altering the timeof weaning, growth rates for both pre- and post-weaning will change. One set of pigs was weaned at20 days, and the other, a control at 32 days.Radiographs taken at a frequency of three times aweek for a total of 70 days were digitized, anddifferences in growth rates were tested usingANCOVA. In both the early weaned pigs and thecontrols, snout width, facial width, basicranial length,and basicranial width growth rates slowed at the timeof weaning. However, in facial length and snoutlength, there was no significant change in growthrates with either treatment at weaning. In conclusionthe growth rates of some variables could be changedby altering the time of weaning. This implies growthrates were epigenetically regulated through dietarycontrol.

CRANIOFACIAL HETEROCHRONY IN THE SHORT-TAILED OPOSSUM. M. Maunz. Univ. of Cincinnati,Ohio.

Growth patterns of bones within the skull can varydepending on the location and function of each bone.I measured the craniofacial growth of twelve maleshort-tailed opossums(Monodelphis domestica) fromthree litters, to determine differences in growthbetween bones of the viscerocranium andneurocranium. From longitudinal radiographsdocumenting individual growth, I measured lengths ofthe palate, mandible, basisphenoid, basisphenoid-basioccipital, and the total skull to represent the twocranial regions. I used a Gompertz nonlinear modelto compare growth between these bones todetermine the mechanism(s) that may play a role invariate growth. Initial lengths for measurements inboth skull regions average the same size. Immediatevariation in growth is demonstrated by theinstantaneous growth rate at time zero, or birth.Values for both the mandible and palate growthexhibit faster acceleration than either neurocranialbones. The initial growth of the basisphenoid of thefirst two litters grew slightly faster than the third.Despite this variation, the final lengths of all animalswere similar for each measurement. Subsequentchanges in growth resulting in differences in headshape are probably associated with the changes inmasticatory function due to weaning and growth anddevelopment of the brain.


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446AQUACULTURE IN TURN-OF-THE-CENTURYJAPAN.M. Landau, Richard Stockton Col legeof New J e r s e y , Pomona.

Aquaculture in Japan during theperiod between 1890 and 19]0 typified thetransitional stage between the old tech-niques used before the restoration of1868 and the s ta r t of the modem aquacult-ure period which coincided with the endof the second world war. The dominantculture organisms during that periodincluded sate of those which are currentlyimportant although new techniques havebeen developed (e.g. oysters, scallops,seaweeds and pearls) . Other organisms(e.g. acom barnacles and ark-shells) areno longer cultured on a caimercial basis .

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447 448POTENTIAL TRANSFER OF DREISSENA INTOLAKE PONTCHARTRAIN VIA BONNE CARRESPILLWAY.P.S. Glas* and B.A. Thompson. Louisiana StateUniv., Baton Rouge.

The opening of the Bonne Carre Spillway forthe first time in 11 years presented an opportunityfor entrance of the invasive Dreissena from theMississippi River into the brackish LakePontchartrain system. The floodgate removalscoincided with a peak in the number of Dreissenaveligers in the river water column. The flow ofriver water was traced for at least two miles intoLake Pontchartrain by the USGS. LakePontchartrain conditions were found to be tolerableto Dreissena (Nalepa and Schloesser, 1993; Claudiand Mackie, 1994; T. Deitz, pers. comm). Apopulation of Mytilopsis leucaphata found in LakePontchartrain and the Bonne Carre Floodwaycollaborated the suitability of the environs. Thesefindings suggest Dreissena veligers transportedinto the Bonne Carre Floodway and LakePontchartrain may find suitable habitat for survivaland reproduction. There is also potential forcohabitation of Dreissena and Mytilopsis aspredicted by Pathy and Mackie (1993). Supportedby Louisiana Sea Grant College Program, a part ofNational Sea Grant College Program, NOAA,U.S. Dept. Commerce.

EXOGENOUS NEUROTRANSMITTERINDUCES UNIONID GLOCHIDIAL RELEASER.V. Dimock, Jr.* and R.W. Strobe, Wake ForestUniversity, Winslon-Salcm, NC.

Physiological control of the release of glochidialarvae by unionid mussels is not well understood.Both exogenous and internal application ofmolluscan neurotransmitters can induce gameterelease in marine bivalves and the zebra musselDreissena. Gross behavior of adult unionids,including rhythmic valve adduction and burrowing,have been elicited by serotonin (5-HT) or otherpharmacologic agents. We have explored theeffects of serotonin, acetylcholine and dopamine ongravid anodontine mussels (Utterbackia imbecillisand Pvpanodon cataracta). Glochidial release wasmonitored by video, including endoscopy withinthe suprabanchial chamber. At 10'5 M, 5-HTinduced release via the exhalant siphon within 20-40 min. Release was preceded and accompanied byrhythmic valve adduction at approximately 0.75adductions/min. Glochidia emerged as a mucous-bound stream or web from Ulterhackia. but wereexpelled more nearly in 'puffs' by forceful valveadduction in Py^anodon. Neither acetylcholine nordopamine stimulated release. Exposure of a gravidVillosa lienosa to 10"5 M 5-HT for 60 min resultedin the rapid expulsion out the exhalant siphon of asingle conglutinant. These data suggest that ex-ogenous 5-HT may induce release of glochidiafrom various species without undue mechanicaltrauma to parental mussels.

449 450

WHAT ARE THE PHYSIOLOGICALRESPONSES OF UNIONID MUSSELS TOCOLONIZATION BY ZEBRA MUSSELS?D.J. Hornbach*, S.M. Baker, T.Oeneka. Macalester College, St.Paul, MN.

We examined the oxygen uptake,ammonia excretion, and clearancerates, of unionid mussels(Actinonaias ligamentina)colonized by zebra mussels(Dreissena polymorpha). When foodsupply was adequate, there were nodifferences in O:N ratios betweencolonized and control Actinonaiasfollowing one and two months ofinfestation. Fed an inadequatefood supply, colonized Actinonaiashad significantly lower O:N ratiosthan the controls, following bothone and two months ofcolonization. These differencesin O:N ratios were primarily dueto lower oxygen uptake rates inthe colonized mussels. Unionidclearance rates were alsosensitive to colonization, zebramussel infestation significantlyalters the physiological state ofunionid mussels, especially whenfood supply is low.

ORGANIZATION OF GILL MUSCULATURE IN THEZEBRA MUSSEL, DREISSENA POLYMORPHA. S.Medler and H. Silverman. LouisianaState Univ., Baton Rouge.

The gross organization of gillmusculature was studied usingmicroscopic techniques. Therelationship of muscle bands to thestructural connective tissue elementsof the gill would appear to beparticularly important in theregulation of water flow through thegill. Muscle bands run in bundlesembedded in a fibrous connectivetissue, crossing gill filaments atright angles. These larger bundlesassociate with muscle fibers which runaround and between ostia in a web-likepattern. The orientation of thismusculature is consistent with apulling on the thicker structuralelements during contraction, decreasingostial diameter and interfilamentdistance. Relaxation of themusculature causes the oppositeresponse. Serotonin relaxes gillmusculature while FMRFamide andacetylcholine stimulate contraction.(Supported by R/ZM-1-PD).


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ANNUAL REPRODUCTIVE CYCLE OF THEZEBRA MUSSEL: A COMPARISON OFGREAT LAKE AND RIVERINE FORMS.D. H. Gist*, M.R. Miller, and W. A. Brence.University of Cincinnati.

The annual reproductive cycle of Dreissenapolymorpha was determined by histologicalexamination. Gonadal development in Lake Erieforms commenced overwinter; by June, spawninghad yet to occur; some but not all testescontained spermatids and sperm. Femalescontained large numbers of mature oocytes loosewithin the cysts By August, spawning hadcommenced and cysts contained oocytes ofvarying stages and sizes in addition to youngsmall oocytes on the periphery. Males possessedfully developed testes, and mature sperm wereevident By October, the gonads had emptiedand it was difficult to determine sexhistologically. In contrast, complete gonadalregression was not seen in the Ohio Riverpopulation. Females contained yolked oocytesthroughout the year, and some males possessedspermatids during the winter months. There wasconsiderable variation among individuals at anypoint in the year. Spawning in the riverpopulations commenced in July and continuedthrough September

This poster will review and compare 1994zebra mussel (Dreissena spp.) veligerdensity data with those that were collec-ted since 1991. The objective of thisanalysis i s to i l l u s t r a t e differences andsimilar i t ies in veliger density trendsbetween these years. Four locationsalong the upper Niagara River were sampl-ed weekly from June 1991 through December1994. Generally, veliger density fluctu-ated in magnitude and spawning durationthroughout the four year period. Spawningseason occured early in 1991 and wasbrief, s tart ing in July and concluding inearly September. The 1991 season wascharacterized by relat ively high densit-ies occuring over a short period of time.The spawning seasons in 1992 through 1994were much longer then those observed in1991. In 1992, spawning was observed bymid-July and concluded in November. Thespawning seasons of 1993 and 1994 did notoccur unt i l September and was characteri-zed by moderate to high densi t ies . 1993and 1994 spawning seasons were relativelyla te in the year compared to ea r l i e rseasons. Viable veligers were observedeach year during winter months when watertemperatures were less than 2.0 C. Thisposter will incorporate the four yeardata set and will summarize inter-annualvariations of veliger density.

453 454

ULTRASTRUCTURAL COMPARISON OF THEORAL COMPLEX IN TWO CONGENERICPERITRICH CILIATES.J.C. Clamp* and P.C. Bradbury. N.C.Central Univ., Durham and N.C.State Univ., Raleigh.

Significant ultrastructural dif-ferences between the oral complexesof the peritrich ciliates Ellobio-P_hrya conyiya and E.. brevipes,ectosymbionts of marine bryzoansand skates respectively, wererevealed by transmission electronmicroscopy. Ellobiophrya convivalacked the ribs in the infundibularwall described in other genera ofperitrichs, but E_. brevipes pos-sessed them. Also, the myonemalsphincter that controls the openingfrom the infundibulum into the cy-tostomal region was much larger andthicker in E. brevipes than in E.conviva. Such gross ultrastructuraldifferences between congeneric spe-cies have not been described inother peritrich genera and may berelated to observed differences inthe diet of the two species ofEllobiophrya.

MORPHOLOGY OF THE"MICROVASCULATURE" IN GILLS OF THEBLUE CRAB, CALLINECTES SAPIDUS.M. Gallagher, and D.L, Lovett*. Trenton StateCollege, NJ.

In gills of the blue crab, Callinectes sapidus, theepibranchial and hypobranchial "microvessels" liesubjacent and parallel to the afferent and efferentbranchial vessels, respectively. In the presentstudy, the gross morphology and ultrastructure ofthe microvasculature were examined. We havereported previously lhat these two microvesselsare confluent with the excretory ducts of acinarglands that line both of the branchial vessels.Others have described these acinar glands astegmental glands, which serve to sclerotize thecuticle of the gill. In our studies, no ducts werefound to communicate between the acini and thesurface of the epidermis. The epi- andhypobranchial microvessels also communicatewith each other through branches which extendtransversely across the gill at regular intervalsalong its length. At the proximal end of the gill,the epi- and hypobranchial microvessels reflectaway from the branchial vessels, fuse, penetratethe body wall, and extend into the body as ananastomosing network.

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METABOLIC PROFILES OF LOCOMOTORMUSCLES IN TWO PORTUNID CRABS.C.E. Booth*, LM. Apostolides, M.A. Levinand A.E. Sheehan. Eastern ConnecticutState Univ., Willimantic and Univ. of Hartford.

In crabs, depressor muscles in the'thoraxhelp flex the legs during sidewayslocomotion. In the swimming crab,Callinectes sapidus, leg 3 is used for bothwalking and swimming. Ultrastructural andhistochemical examination of the leg 3depressor shows three fiber types: Mostfibers are fast-twitch-glycolytic, but there is asmall, central band of last-twitch-oxidative-glycolytic fibers, and a small number of slow-oxidative fibers. In gross anatomy and fiber-typing, depressor 3 closely resembles thelarger depressor of leg 5, which powersswimming. However, depressor 5 hashigher activities of LDH and citrate synthase(CS), which may explain why swimmingentails faster leg movements but is lessfatiguing than running in C. sapidus. In theactive, but non-swimming portunid, Carcinusmaenus, depressor muscles consist entirelyof fast-twitch-glycolytic fibers, and show lowactivities for LDH and CS. These datasuggest that the evolution of swimming in thePortunidae involved both qualitativechanges in muscle structure and quantitativechanges in muscle metabolic capacity.

A NEW MEIOFAUNAL MARINE HYDR01D:CRYPTOHYDRA THIELI.M.B. Thomas*, N.C. Edwards, and R.P.Higgins. University of North Carolina at Charlotteand National Museum of Natural History,Smithsonian Institution, Washington.

An undcscribcd mciofaunal hydroid wasfound in coarse shell-hash at two sites along theAtlantic coast near Fort Pierce, FL. The motilehydroid is up to lmm long. It has a long proboscisthat separates short oral from longer aboraltentacles; all are used in motility. A basal disc,similar to that of an actinula, is used for morepermanent attachment. Based on the cnidomc(stenoteles, desmonemes, and two sizes ofmicrobasic mastigophores), location of tentacles,type of tentacles, organization of the endodcrm ofthe tentacle, presence of a supporting lamella,structure of the basal disc, and mode of asexualreproduction, the species is assigned to the familyAcaulidae (Athecata, Capitata). Differences fromother members of the family, all of which aresessile, are considered adaptations to a motileexistence, and significant enough to warrant thecreation of a new genus, Cryptohydra.

457 458

MOLECULAR PHYLOGENY IN SPECIES OF THENEMERTEAN GENUS UNEUS.J.L. Norenburg*, A. Rogers, C. Bustamante, and J.D.Ferraris. National Museum of Natural History,Washington, DC, Marine Biological Association, Plymouth,UK, Harvard Univ.,Cambridge, MA, and National Inst.ofHealth, Bethesda, MD.

The genus Uneus, at about 100 species, is one of thelargest in the phylum Nemertea. It is a recognizedartificial assemblage, but difficulty in identifyingphylogenctically informative morphological charactersclouds systematic work, We used nucleotide sequence dataof two fragments of ribosomal DNA, nuclear 28s (300bp)and mitochondria! 16s (500bp), to begin examining intra-and interspecific genetic relationships in the genus. Thestudy included intertidal populations of L. rubcr and L.viridis, widely distributed and abundant species, both fromthe NE and NE Atlantic, L. socialis (NW Atlantic), L.sanguineus and L. nigricans (both NE Atlantic):Cerebratulus lacteus was uses as an outgroup. The latterthree Uneus were recently synonymized and transferred toanother genus (Riser, in press, Proc. Biol. Soc. Wash.).Our results bolster Riser's assertion that they arc amonophyletic unit, although this may be as three species ina different genus. Uneus ruber and L. viridis comprise amonophyletic unit that includes some strongly variantindividuals: the latter may represent a cryptic speciespreviously recognized with allozyme criteria by Rogers et.al. (in press). The five Uneus species remain amonophyletic unit when the outgroup is included but notdesignated.

SPECIES IDENTIFICATION OF SIPUNCULANLARVAE BY ANALYSES OF RAPD DNAPOLYMORPHISMSLisa G. Bates, Laura Adamkcwicz* and Mary E.Rice, Smithsonian Marine Station, Fort Pierce,Florida and *Gcorgc Mason University, Fairfax,Virginia

Sipunculans have a long-lived, planktotrophicpclagosphcra larval stage which is responsible forthe animal's dispersal anil genetic exchange.Morphologic similarities between sipunculanlarvae and difficulties in rearing the larvae to theadult form in the laboratory have caused theidentification of the larval species to remain quitetenuous. Randomly Amplified Polymorphic DNAand the Polymcrasc Chain Reaction (RAPD-PCR)were used to screen 80 primers in order to find twowhich produced molecular markers capable ofdistinguishing between Siplwnosoma ciwumenseand Phascolosoma tumevae. The same bandingpattern was demonstrated for adults and larvaespawned from known adults for both species. For5. cumanense, putativcly identified individualplanklotrophic larvae and juveniles reared fromlarvae were included. Now that a correspondencebetween the adult and larval markers has beenestablished, we expeel to be able to distinguishother planktotrophic sipunculan larvae and belterunderstand their biogcographic and evolutionarysignificance.


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ANTHOZOAN MT DNA: A FUNDAMENTALLYDIFFERENT RATE OF EVOLUTIONB. A. Best and W. K. Thomas. Colby College,Waterville, ME and Univ. of Missouri, Kansas City.

MtDNA of Anthozoans (Phylum Cnidaria) exhibitsa very slow rate of evolution in contrast to the rapidsubstitution rates in third positions in a variety ofanimals. Direct sequencing of a 486 bp region ofmtDNA COI from three coral species {Acroporapalifera, A. cuneata and A. hyacinthus) reveals nointraspecific sequence variation in these species, incontrast to significant protein variation. In addition,there is no interspecific sequence variation betweenA. palifera and A. cuneata (brooding species), andvery little variation between those species and A.hyacinihus (broadcasting coral), despite significantmorphological and protein variation between species.To test whether the observed lack of sequencevariation is due to recent divergence or to a slow rateof mitochondrial evolution in these animals,additional cnidarian sequences were collected. Thirdpositions of these cnidarian sequences, as well asthose from the comparable region in mammals andplants, were analyzed for both uncorrected percentsequence difference and Kimura's two-parametermodel corrected percent sequence divergence.Evolutionary rates at third positions of AnthozoanmtDNA are very low compared with rates of thesame coding region from mammals, but appear to bemore similar to the rate observed at comparablepositions in plants.

SYMBIOSIS BETWEEN A SEA ANEMONE/,ND A SCAPHOPOD: REDUCING THEDIFFICULTIES OF DEEP SEA LIFE?A.K. Wakefield Pagels* and D.G.Fautin. Univ. Kansas, Lawrence.

At a site 4100 hi deep and 200km off the California coast, a seaanemone occurs only on shells ofliving scaphopods; most scaphopodshave or have had an anemone. Thescaphopod belongs to a new speciesor possibly a new genus; taxonomyof the anemone is under study. Inthis soft-bottom habitat, theshell provides a firm substratumfor anemone attachment, and thescaphopod may transport the anem-one to food. The anemone may pro-tect the mollusc from predation,and may prevent sea water fromcontacting the shell, which candissolve readily at this site nearthe calcium carbonate compensationdepth. Because the scaphopod istrawled, we infer it is atypicalin living on the surface ratherthan burrowing into the sediment.This inference is consistent withthe anemone's being wrapped aroundthe shell -- carrying the anemonethrouch sedinent would bs 3 dr=;.

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OVERSHADOWING IN THE LEARNING OFHONEYBEES.E.T. Mateo* and P.A. Couvillon and M.E.Bitterman, introduction by M. Switzer-Dunlap,University of Hawaii at Manoa, Honolulu.

Honeybees trained with two colored feedingtargets, one rewarded with a 20 id drop of 50%sucrose and one with a 5 /tl drop, show a prefer-ence for the 20 y\ color in unrewarded choicetests. If the locations of the drops are markedwith a small white dot, no preference develops;learning about color is overshadowed by the dots.This effect does not occur if the rewards differ inconcentration, nor with odors instead of colors.Overshadowing of color by dots is found herewith differences in probability of reward, butovershadowing of odor is not. Individual foragerswere trained to repeatedly visit an experimentalwindow for 50% sucrose solution. Bees werepresented with two targets, one rewarded with a10 (*1 drop of sucrose on each presentation (con-sistent), and the other rewarded on only half ofits presentations (partial). Dots marked the loca-tion of the drops on the targets for half the bees,and the targets were unmarked for the rest. Thedot interfered with learning about color but notabout odor. The results suggest perceptual compe-tition for attention in the learning of honeybees.

RECOGNITION OF POLARIZATION CONTRAST BYOCTOPUS

N. Shashar • and T.W. Cronin. Dcpt. of BiologicalSciences, University of Maryland Baltimore Ccuniy,Baltimore, MD, 21228, USA.

Animals are known to use their sensitivity 10 thee-vector orientation of light (polarization sensitivity) fornavigation, spatial orientation, and for finding large bodiesof water. A fundamental question to understanding thefunction of polarization sensitivity is: can animals usepolarized light to detect or identify specific objects?Objects such as fish and plants reflect polarized light in asignificantly different pattern from their depolarized lightappearance. However, no animal has yet been shown touse polarized light for object detection or recognition.Octopuses are known to possess polarization sensitivity,and although the anatomical basis for this has long beenunderstood, its function is not yet known. We trainedoctopuses to discriminate between targets based on thepresence or lack of a 90° polarization contrast within thetarget. Octopuses recognized a 90° contrast both on ahorizontal/vertical and a 45°/I35° axis. The animals wereable to detect a polarization contrast when the e-vectororientation of the target center and background differed byas little as 20°. These results show that octopuses can usepolarization vision for recognition of objects and possiblyfor their detection as well.

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REGULATION OF CHEMICALLYSTIMULATED FEEDING BEHAVIOR INSAND FIDDLER CRABS Uca pugilaiorBY A SINUS GLAND PEPTIDE.M. A. Duval. Duke University MarineLaboratory, Beaufort, NC.

Sand fiddler crabs Uca pugilaior arescmi-tcrrcstrial deposit-feeders. Crabsspend the majority of their activity periodforaging. Previous studies demonstratedthe existence of a feeding inhibitory factor(FIF) in the cyestalks and hcmolymph ofcrustaceans. In the present study this factorhas been localized to the sinus gland ofboth Uca pugilaior and Penaetis duorarum.Injection of feeding inhibitory factor intostarved crabs results in a significantly lowerresponse to chemical feeding stimulants.Effects of feeding inhibitory factor onhcmolymph glucose levels weredetermined. We suggest that feedinginhibitory factor is a sinus gland hormonethat may be an invertebrate analog ofcholecystokinin, a satiety hormone invertebrates. Moreover, we postulate thatvariation in hcmolymph levels of FIF mayaffect movement and/or orientation offoraging crabs.

ACTIVATION OF BRINE SHRIMP NAUPLIIPHOTORESPONSES INVOLVED IN DIEL VERTICALMIGRATION BY CHEMICAL CUES FROM VISUALAND NON-VISUAL PLANKTIVORES.L.M. McKelvey* and R.B. Forward, Jr. Duke UniversityMarine Laboratory. Beaufort, NC.

The effects of exposure to visual (3 fish species:menhaden larvae, pinfish, and mummichogs) and non-visual (ctenophorcs, cheatognalhs, and blue crab postlarvae) planktivores on the photorcsponses involved in thedescent phase of nocturnal diet vertical migration (DVM)of brine shrimp naupliar larvae were measured in alaboratory system that mimicked the underwater angularlight distribution. This study shows that brine shrimpnauplii have an inducible phenotypic response to differentplanktivores. Photoresponses were activated by 1 dayexposure to (1) all 3 fish species and (2) water that hadpreviously contained fish or ctcnophores. Thus, chemicalcues from both visual and non-visual planktivores activatedphotoresponses, contrary to the hypothesis that DVMfunctions for avoidance of visual predators. Activationoccurred within S min. and photoresponse sensitivitydecreased with decreasing concentration of chemical cue.In contrast, pholorcsponsc activation was very weak afterexposure to chcatognaths and blue crab megalope. Theresults support the predication that activation ofzooplankton DVM should vary with exposure to differentplanktivorc types and abundance.

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NADPH-DIAPHORASE STAINING IN THENERVOUS SYSTEMS OF LARVAE ANDJUVENILES OF THE PROSOBRANCHMOLLUSC ILYANASSA OBSOLETA.M.-F. Lin* and E.M. Leise. University ofNorth Carolina Greensboro.

NADPH-diaphorase colocalizes withneuronal nitric oxide synthase (NOS) andhas been used as a marker for NOS in bothvertebrates and invertebrates. NOS hasrecently been found in the CNSs of adultgastropod and cephalopod molluscs(Chicery and Chicery, NeuroReport5(1994):1273-1276; Moroz et al.,NeuroReport 5(1994):1277-1280),but theontogeny of NOS-containing neurons inmolluscs is unknown. We used NADPH-diaphorase histochemistry, modified from K.Lukowiak (personal communication) to mapthe distribution of NO-synthesizing neuronsin the CNSs of competent larvae and post-metamorphic juveniles of the prosobranchmollusc llyanassa obsoleta. In both larvaland juvenile forms NADPH-diaphorase islocalized in the neuropils of the cerebral,pedal, pleural, buccal, visceral andosphradial ganglia. The apical ganglion, aspecialized larval structure, stains relativelydensely. Neuropils in juvenile snails stainmore intensely and appear to contain greateinumbers of NOS-containing neuronalprocesses.

CONFOCAL AND EPIFLUORESCENTIMAGING OF THE NERVOUS SYSTEMSOF JUVENILES AND COMPETENTVELIGER LARVAE OF THEPROSOBRANCH MOLLUSC ILYANASSAOBSOLETA.E.M. Leise *. University of North CarolinaGreensboro.

The apical ganglion, a uniquely larvalstructure that contains the cephalic sensoryorgan, lies just dorsal to the cerebralcommissure in opisthobranch molluscs(Marois et al. Soc. Neurosci. Abstr.19(1993):1287). Metamorphically competentlarvae and young juveniles of theprosobranch gastropod llyanassa obsoletawere exposed to the fluorescent dyeDASPEI at 10mM in 90% SW for 20 mins.In the CNS, 6 to 8 cells of the apicalganglion stained routinely, while the neuronsin the rest of the central ganglia, with only afew exceptions, remained unstained.Previously, this vital dye has been used tostain mitochondrial-rich cells, such as haircells in the lateral line systems of teleostsand chloride cells in their skin. In llyanassalarvae this dye also stains two to four cellsthat may be sensory neurons, at the tip ofeach tentacle. The selective staining of theapical ganglion suggests that this structureplays an essential role in the coordination oflarva! behaviors.


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5-HT INJECTIONS INDUCEMETAMORPHOSIS IN LARVAE OF THEGASTROPOD MOLLUSC ILYANASSAOBSOLETA. J. M. Couper* and E.M. Leise.University of North Carolina Greensboro.

The serotonergic neurons present in larvalllyanassa obsoleta may be involved in theinduction and/or completion ofmetamorphosis in these animals (Kempf,S.C. Soc. Neurosci. Abstr. 17(1991): 1356).Serotonergic neurons are known to controlciliary beating and settlement behaviors inseveral molluscs, and bath-applied 5-HTreliably induces metamorphosis incompetent llyanassa within 24 hours.Metamorphically competent, swimminglarvae were injected with 220 pL of 10'6M 5-HT using a glass micropipette attached to aPicospritzer. 5-HT was injected laterally, 25Urn behind the eyespots. Approximately55% of 5-HT-injected larvae metamorphosedwithin 24 hrs, compared to 17% of seawater-injected controls. After 48 hours, respectivevalues were 70% and 30%. Although bath-applied 5-HT induces metamorphosis inllyanassa larvae, injection of theneurotransmitter removes the possibleconfound of uptake across the epithelium.The outcome of 5-HT injections using thismethodology suggests that the compoundplays a central role in the metamorphosis ofllyanassa larvae.

TRANSECTION OF THE MANTISTYMPANAL NERVE HOMOLOG IN THECOCKROACH ALTERS RESTING POSTURE,ESCAPE TURNING, AND RESPONSES TOSUBSTRATE VIBRATION.D.D. Yager* and K.C Tola. Univ. of Maryland,College Park.

Most mantises have sensitive tympanatehearing, but their closest relatives, thecockroaches, do not. Nerve 7, the cockroachhomolog of the mantis tympanal nerve,comprises axons innervating socketed hairson the ventral metathorax and a chordotonalorgan with 40-50 sensillae. Transection of N. 7alters posture: the leg on the operated side isheld more flexed and closer to the body thannormal. Thresholds for response to wind(escape turning) and substrate vibration (headand antenna motion) are higher aftertransection, and the resulting behaviors areattenuated compared to controls. Changes invibration responsiveness appear to beindependent of the altered posture. UnilateralN. 7 cuts yield primarily ipsilateral behavioraleffects. Leg proprioception and vibrationdetection are thus prime candidates asfunctional antecedents of mantis hearing.

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COMPARATIVE GROWTH AND DEVELOP-MENT OF THE CORPORA PEDUNCULATAAND ANTENNAL SYSTEM IN THE BRAINOF PERIPLANETA AMERICANA.G.M. DeClark, M.M. Maine, and R.J.Stark*. DePauw U, Greencastle, IN.

The mushroom shaped CPs of the arthro-pod brain have been hypothesized to besites for memory linked to the antennal lobe(AL) olfactory system. During nymph devel-opment, new cells are continuously beingadded to the apex of the CP and form newneurons as they move dorsilateral. The ALadd no new cells during nymph development,even though the antennae grow with eachmolt cycle increasing sensory input to theAL. Video imaging and 3D reconstructions ofthe AL and CP in serial sections of brains ofInstars 1,3,5,7 and Adults were used to ex-amine the development of these regions.The volume of the AL increased proportional-ly to the growth of the antennas and CP (cor.coeff. 0.989-0.960) even though, no newneurons were added to the AL and therewere no increases in the number of synapticdensities in the AL. (Supported by H.HughesMedical Institute Research Grants)

ANDKOGEN METABOLISM IN THETUNICATE, STYKLA PUCATA.C:.A. Ityruin*, (iisiu: A. I lines, mid .Stephen A.WatU. University of Aluhumu at IJinningham.

Although steroid metabolism in vertebrateshas been well documented, very little is knownabout steroid metabolism in the invertebrates,particularly that of the urochordatcs. Previousstudies examined the steroid conversion capacityof urochordute gonads using progesterone andpregncnolone as precursors, however similarstudies have not been reported using androgens.Slyela plicala were collected from St. Joseph Bay,Florida. The tunic, endostyle, dermis/epidermisand gut were removed and incubated with '*H-androstene-3,17-dione. Following incubation,tissues were organically extracted and freesteroids were identified by TLC, chemicalderivatizations and recrystallizations. Alltissues produced principally testosterone and insome cases an eslcrificd testosterone. Minorproducts included epiandrosterone, 5it-androstancdionc, and a polar mi'ltibolitc that mayrepresenl a trioxygenated androgen. Based on theseresulls, 3p-HSD, 17f>HSD, 5u-reductase and anunidentified acyltransferase are present in S.plicala tissues. These metabolites are similar tothose produced by echinoderms and some vertebratetissues, however the physiological significance ofthese pathways in urochordates is unknown.Supported by NSF.

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SURVEY OF UV-ABSORBING COMPOUNDSIN SUB-TROPICAL SEA URCHINS FROMFLORIDA AND THE BAHAMAS.I. Bosch, P. Janes, R. Schack, B. Steves* andD. Karentz. SUNY College at Gcnesco, Univ. ofSan Francisco.

Spcctropholometric analyses of mcthanolextracts from body wall and reproductive tissuesof sea urchins revealed high levels of UV-B andUV-A screening compounds in 4 of 6 shallowwater (< 5 m) species surveyed. No capacity forscreening UV was detected in. samples repre-senting 5 species of sea urchins collected atbathyal depths with the Johnson Sea-Linksubmersibles. Samples of the shallow waterLytechinus variegatus and Tripneustesventricosus analyzed by HPLC were found tocontain high concentrations of a variety of UV-absorbing Mycosporinc-Likc Amino Acids(MAAs), principally palythinc (320 nm), shino-rinc(334 nm), and mycosporinc-glycinc(310nm). Protein-specific concentrations of MAAswere about 2.5 limes greater in ovaries and eggsof L. variegatus (n=3) than in tcsles (n=4) and1.75 times greater than in the body wall (n=4).A similar pattern of higher MAA concentrationin ova and ovaries has been found in Antarcticinvertebrates, including the sea urchin Sterechinusneumayeri.. However, the total concentrations ofMAAs arc nearly two orders of magnitude higherin the sub-tropical shallow water species surveyed.

DO RANDOM SKELETAL ASYMMETRIESCHANGE DURING DENDRASTERDEVELOPMENT?R. Collin. University of Washington, Seattle.

Fluctuating asymmetry (non-directionaldeviation from bilateral symmetry) is thought toreflect the robustness of an organism'sdevelopmental program. However, if animals:ompensate for asymmetries induced duringontogeny, levels of FA may reflect proximity toperturbations rather than the organism's inherentdevelopmental stability. In order to determine iflevels of FA vary during development I raisedindividual larvae of the sand dollar Dendrasterexcentricus. I measured asymmetries of thepostoral, anterior-lateral and postdorsal skeletalrods. The postdorsal rods showed initially rightbias asymmetry that was subsequentlycompensated for during development. Variancesof FA for the other characters decreased duringdevelopment. Also, measurements of individualssuggest that initially asymmetrical animalsbecome more symmetrical while asymmetries ininitially symmetrical ones tend to increase.

474 475

ECOLOGICAL CORRELATES OF ARCTICSERPULIDAE (POLYCHAETA)DISTRIBUTION. E. K.' Kupriyanova and A.V.Badyaev. Univ. of Arkansas, Faycltevillc andUniv. oT Montana, Missoula.

We studied habitat use and distribution of 10serpulid species by analyzing 635 samplescollected from the Arctic Ocean. We usedprincipal component and correspondenceanalyses to develop a model that emphasizeddepth and substrate as the two major gradients.Species differed in their distribution along thesegradients. Discriminant function analysisrevealed that sites occupied by Protis arctica.Pomatocerus triquetcr. and Serpula vermiculariswere most homogeneous based on habitatvariables considered. Habitat used by Apomalusnlohifer. Filonrana implexa. Hydroidcsnorvenica. and Placostegus tridentatus were themost variable and complex. Variability of sitesoccupied by Protula tubularia and Ditrupaarictina were intermediate. Variability of realizedhabitats accounted for 80% of variation inspecies' geographical ranges. Information onmore species is needed to determine theinfluence of habitat specialization on presentnoKchnetc distribution.

DISTRIBUTION OF CANCER IRRORATUS AND C.BOREALIS ON THE BASIS OF HABITATCOMPLEXITY IN THE GULF OF MAINE. C. A.Cibcaull (Intro, by L. G. Harris). University of NewHampshire, Durham.

Quantitative monthly samples estimated theabundance of Cancer irroratus and C. borealis in severalhabitats (coarse sand, bedrock, cobble, small boulder,and algal bed). Monthly samples were made using bandtransects for all size classes and airlift samples to collectsmaller recruits from May to November, 1994,at coastallocations in New Hampshire and southern Maine. Newlysettled individuals (<10 mm carapace width) werecollected from sandy sediments within all five habitattypes, whereas larger individuals (60-120 mm) were foundin greater abundance in small boulder, algal bed, andsome bedrock crevices. More complex habitatssupported a greater diversity of crab sizes, whereas moreuniform habitats supported a narrower size range. Forexample, juvenile crabs dominated coarse sand samples(3-10 mm), while algal beds were occupied by all sizes ofcrabs. Therefore, it appears that the species exhibitvariation in habitat use during the life cycle.

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SHELLS AND HABITAT CHOICE BYSTRIPED LEGGED HERMIT CRABS.D. Ritlschof*, J. Sarrica and D. Rubcnstcin.Duke University Marine Laboratory, BeaufortNC.

Questions relating shell fit to hermit crabbiology have entertained behaviorisls,physiologists and ccologists for over 40 years.Shells and their quality are implicated in everyaspect of hermit crab biology from populationregulation to individual growth, survival,fecundity, and even sexual exploits. Here we usebehavioral measures of shell fit in Clibcuwriusvittatus to assess shell resources and use ofhabitat. We show shell resources vary with limeand between sites. Shells arc relatively smallwhen the population peaks in the fall. Many crabsoccupy shells that arc loo large in .spring whenpopulations are low. Intermediate sizes of shellsform a population bottleneck after recruitment.We show crab location within habitats is relatedto shell fit. Crabs in all sizes of shells are capableof extensive movements. Thus, habitat location isdue to other than restricted mobility. Crabs inshells that are too large live throughout the habitatof intcrtidal oyster reefs and mud/sand flats andallow exposure at low tide. Crabs with shells thatarc just right remain in mud sand habitats and maybe exposed at low tide. Crabs in shells that arc toosmall are restricted to subtidal mud/sand habitats.Shells are a dynamic resource and crab location inthe habitat is related to shell fit.

Most reports of portable ormobile sponges identify thegastropod shell substrates onlysporadically or not at all. Inthis study 622 FL hermit-crabsponges from the Gulf of Mexicowere examined and the shellsubstrate identified. Ninesponges were on living snails(Cantharus cancellarius), 239were occupied by a hermit crab,either Pagurus impressus (96%)or Paguristes hununi (4%) , and367 (59%) were found empty.Twenty different gastropods andone scaphopod were found but 3spp. -- Cantharus cancellarius(71%), Nassarius acutus (12%),and Pyrgospira ostrearum (7.5%)-- comprised the substrate inover 90% of the sponges. Someshells were small (< 3 mm) andmost were in good condition,showing no erosion or damage bythe surrounding sponge. In 8sponges no shell was found.All shells were covered bysponge gemmules. The resultsdo no support the idea ofsubstrate specificity.

478 479

GENETIC INFLUENCE ON GROWTH, AB-SORPTION, AND TISSUE WATERCONTENT IN THE CLONAL SEA ANEMONEHALIPLANELLA LINEATA. M.G. McMa-nus*, W.E. Zamer, and M. Amsler.Lake Forest College, IL.We have begun to explore genotypeinfluences on performance by mea-suring growth rate and absorptionefficiency in 5 isogenic clonesof H . lineata. Rations ofArtemia sp. were fed to anemonesand egesta were collected at15°C. Growth rate was surpris-ingly variable within clones(C.V.s=22-48%) , and lead to simi-lar means among clones (mean=3.5%dry mass-d'1; n=40 anemones).Absorption efficiencies did notvary among clones either(mean=93%; n=30 anemones). Tis-sue water content varied amongclones (range=81-84%; F430=10.3,p < 0.001). Genotype do'es notinfluence gravimetric growth orabsorption in this species. Dif-ferences in tissue water amongclones may reflect differences intissue lipid content, a possibil-ity we are exploring. Supportedby NSF, DCB 9057315 to W.E.Z.

REGULATION OF REPRODUCTIVE BEHAVIOR IN THEANTARCTIC PTEROPOD CLIONE ANTARCTICA:PRODUCTION OF SEX STEROIDS. P.J. Bryan*. G.A.Hints. M.H. Stallcry. K.M. Wasson, S.A. Walls and J.B.McClinlock. University of Alabama at Birmingham.

In si in observations of Clione aniarciica in McMurdoSound, Antarctica indicated that 9% or the population werepaired and actively copulating during a September 1993census. Reproductive behavior in fish has been correlatedwilh the release of walcr-solublc sex steroids. Due lo thepelagic nature of this common ptcropod it is possible lhat theirreproductive behavior is regulated in a similar manner.Utilizing radiolraccr techniques, we have analyzed theslcroidogcnic capacity of C. aniarciica to determine if Ihcscorganisms produce sex steroids. Chonc aniarciica (n=9) wereincubated in vivo in artificial scawalcr (ASW) al 0° Ccontaining cither a 'H-projcstin or 'll-androjcn pnvursor.Individual picniprxls were removed from the ASW anil biiilithe organism and Ihc ASW were analyzed fm Ilie |ucsciiteolradiolabclcd slcroidal metabolites. I'tcropods werehomogcni/.cd ihcn extracted with an organic solvent while IhcASW was first treated wilh cleaving cn/.ymes I in order looblain Ihc free (non-conjugated) slcroidal moiclyl and Ihcnextracted. The analysis of Ihc organic extracts indicated theproduction of 5«-prcgnanc-3.20-dionc. several olhcrprogcslins and cslcrificd progestin derivatives. Additionally.5«-androslanc-3.17-dionc. several other 5«-reducedandrogens. cslcrificd androgen derivatives and theconspicuous absence of testosterone was revelled. Analysis ofthe ASW revealed the presence of water-soluble progcslinconjugates potentially including l7«-hydroxyprogcslcronc.These results indicate thai C. aiuurciica have Ihc in vivocapacity lo produce both free and walcr-solublc steroids.These compounds may be related lo Ihc regulation ofgamctogencsis or intcr-organismal (phcromonal) reproductivebehaviors.

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RELATIONSHIPS BETWEEN ENDOHELM1NTHFAUNA AND FEEDING HABITS IN THE1CHTHYOFAUNA OF THE UPPER SAN MARCOSRIVER.H.T. Underwood. Texas A&M Univ., College Slalion.

Thirty-four species of endohelminths were recoveredfrom 1837 fish collected from the Upper San Marcos Riverover a two-year period. 1770 fish (%%) were infectedwith at least one endohelminth species. Endohelminthswere categorized by life history strategics and mode oftransmission to the fish host. The categories include:direct penetrators; directly ingested; invertebrate-intermediate host utilizers; and vertebrate-intermediatehost utilizers. Host species were placed into one of threeconsumer levels as determined by their feeding habits.Consumer Level I hosts feed primarily on zooplankton andaquatic insects; Consumer Level II hosts feed on largeraquatic invertebrates and occasional small fish; andConsumer Level III hosts utilize fish as their primary food.

Directly penetrating endohelminths had a similarprevalence in all consumer levels. Directly ingestedspecies-forms exhibited little difference in prevalenceamong consumer levels, while invertebrate-intermediatehost and vertebrate-intermediate host utilizing species-forms had highest prevalence in Consumer Levels I andHI, respectively.

SIZE EFFECTS ON THE VULNERABILITY OF TWOSPECIES OF SIX-RAYED SEA STARS (Lepiasierias spp.)TO FLUCTUATING SALINITYJ. W. Tamplin and W. B. Stickle. Louisiana StateUniversity. Baton Rouge.

/y/>/«t(/r/if/( rpithhmi and L. mpriii were colic*. liMlimn I illlr I'oil Wulli'i, AK, n liny ilii i imli'ii/ol liy llu-Mllsitllill tlrwliipilu-lll t>( a lit-sliunli'l It-its svMi-ill S|KVI»-sweu* di*lcimiiK-d hy IH>III moijthologKal tlumu'lcis nmliliilgnnslte alloy.) me dilleii'iices. In 2oS sea slats, thesptvies eoill|K>siliiin was (i5.7% L. I'pifhliHii. 2H.7% /..a.\pt'm. aiul 5.0% hybrids. I08 ol" these sea stars werecollected from three vertically stratified inlerlidal zones:low (algal zone); middle (Mylilus zone); and high (Fucuszone). Lepiasierias axpera were larger (radius of the centraldisc; length ol* longest ray; wet weight) and were foundmore frequently in the upper reaches of the inlertidal zonethan was L. epichlora. Species composition did not varybetween the low (26.3 % L. aspera, n = 38) and middle zones(27.6% L. aspera, n= 29) but differed slightly in the highzone (36.6% L. aspera, n = 4l). All hybrid individualsoriginated from the high (Fucu.i) interlidal zone. Sea starswere also divided into species and size groups (large; small)and perivisceral fluid osmolality was measured every threehours during a 12 hour 30-10-30 o/oo S fluctuating cycle.Larger individuals perivisceral fluid osmolality fluctuatedless than smaller sea stars' perivisceral fluid osmolality.The perivisceral fluid osmolality of L. epichlora varied moreduring the tidal cycle than that of L. aspera. Largerindividuals of both species are less vulnerable to fluctuatingsalinity than smaller individuals.

ALLOCATION OF BODY COMPONENTS

DURING STARVATION IN LYTECHINUSVARIEGATUS (ECHINODERMATA;

ECHINOIDEA).M.T. Lares* and CM. Pomory. University of

South Florida, Tampa.Lytechinus variegatus can survive ca. 3

months starvation. Individuals were heldwithout food and dissected (8 per dissection)periodically to determine the use of bodycomponents for maintenance. The weight of thebody wall and lantern did not change over 6weeks of starvation. The weight of the gutdeclined significantly in 2 weeks, then decreasedslightly at 4 weeks and 6 weeks. The gonads alsodecreased in 2 weeks, but not significantly, thenremained the similar in size. The percentorganic material in the gut, gonad and body walldecreased over 6 weeks. Energy formaintenance appears to come primarily fromthe gut, as indicated by the decrease in size.However, resources in the body wall and gonadsare also used, as indicated by the decrease inorganic content.

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INTR ASPECIFIC VARIATIONS IN DELTA-C-13WITH BODY SIZE INDICATE ONTOGENETICCHANGES IN THE DIETS OF DEPOSIT-FEEDING POLYCHAETES.B.T. Hentschcl. University of Washington, Seattle.

Benthic juveniles of species that deposit feedas adults face a transition from a relatively high-quality larval diet (yolk or plankton) to a lower-quality adult diet. Digestive and foraging constraintsimposed by relatively small guts and feedingstructures suggest that juveniles might ingest higher-quality foods (e.g. benthic diatoms, freshphytodetritus, animal prey) until they reach sufficientsize to effectively deposit feed. Using stable carbonisotopes as trophic tracer, I explicitly tested whetherthe diets, of benthic juveniles and adults differ andthen made inferences about the dominantcomponents of juvenile and adult diets based on thesimilarity of the delta-C-13 of their tissues to that ofvarious potential foods. I examined 3 spionids and1 ampharetid that inhabit intertidal sandflats. Allshowed significant intraspecific changes in delta-C-13with body size; juveniles had delta-C-13 values thatwere 2-4ppt less than adults. The delta-C-13 valuesand results of subsequent in situ manipulations ofbenthic diatoms suggest that these deposit-feedingpolychaetes gradually change from a juvenile dietrich in benthic diatoms (delta-C013 - -19ppt) to anadult diet that includes increased amounts of detritusderived from C-13-enriched march plants ormacroalgae.

AMERICAN SOCIETY OF- ZOOLOGISTS

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484 485COMPARATIVE MEDIAN LETHAL DOSE STUDIESON TENEBRIO HOLITOR REARED IN MEDIACONTAINING SELENIUM.G.R. Hogan. St. Cloud State Univ.,St. Cloud, MN, 56301.

Selenium compounds were tested fortoxicity on newly emerged J_. molitor.Two groups of insects were maintained incontrol and selenium-supplemented mediathroughout the experimental period.Other groups were transferred to orfrom control medium after one week.Compounds tested were selenate (SA),selenite (SI), selenocystine (SC), andselenomethionine (SM) at supplement per-centages of 0.01, 0.02, and 0.04. Mor-tality ratios were determined and usedto calculate the medium lethal dose(MLD) at various sampling times. Dataindicate that Tenebrio are most sensi-tive to SM and SA. Similar survivalresponses and comparable MLD were notedfor insects exposed to SC and SI. Trans-fer from selenium-containing media tocontrol medium did not prevent the onsetor extent of mortality. However, in-sects grown on control medium for oneweek before transfer to selenium-supplemented media demonstrated consid-erably higher MLD and greater survival.

GROWTH IN A NEW SPECIES OF DF.NTATISYI.I.IS(POLYCIIAETA: SYM.IDAE) .D.E. Russell. Washington College,Chestertown, MD.

Evaluation of selected linear andmeristic features, including some oftaxonomic importance, in specimens of aDentatisyllis species revealedinteresting relationships among featuresand insight into how this syllid grows.Features evaluated included body lengthand width, total number of segments,proventricle length and width, pro-ventricle length to width ratio, and thenumber of articles comprising dorsalcirri. The linear relationship betweenbody length and the total number ofsegments and the slope of thatrelationship suggest that these poly-chaetes grow more by the addition ofnew segments than by the elongationof existing ones, and that new segmentsgrow to full size fairly rapidly. Theproventricle length to width ratio, acharacter used in syllid taxonomy,tends to increase with body lengthapparently due to increasing pro-ventricle length while width remainsrelatively constant.

486 487I-UUDINO AND DIGESTIVE CHARACTERISTICS Ol:

ASP1DOCIIIROTIDA (ECU 1NODERM ATA:HOLOTHUROIDEA) OF HERON ISLAND. GREATBARRIER REEF.T. S. Klingcr •, C. R. Johnson, and J. Jell. BloomsburgUniversity of Pennsylvania, Bloomsburg and the Universityof Queensland, Brisbane.

Aspidochirolida process 12.75±1.05 g- m"2- day"1 ofsediment on the reef flat of Heron Island, and 3.93±1.18g- m~2- day'1 in the lagoon (mcans±l SEM).Bioiurbation by feeding of Aspidochirolida is slow. Timesto completely turn over the lop 5 mm of sediment arc ca.1.9 years on the reef flat and ca. 3.6 years in the lagoon.Relative importance percentages for reworking sediment,calculated from relative density, relative frequency, and thearea under the feeding tentacles of each species, arc 0.48for llolothuria atra and 0.36 for lloloihwia Icucospilota onthe reef flat, and 0.52 for //. atra in the lagoon. Digestiveenzymes arc similar to those of other echinodcrms. Crudehomogenalcs of the gut of //. atra and //. leucospilolaexhibit a-glucosidasc (0.28±0.02 and 0.21 ±0.09 nmol-min"1- mg protein"', respectively), (i-glucosidasc(0.19±0.03 and 0.26±0.11 nmol- min"1- mg protein"1,respectively), and [S-galaclosidasc (0.1S1O.06 and0.09±0.04 nmol- min"1- mg protein"1, respectively)activity with a pH of maximal activity of 7.5-8.0. Tracechymotrypsin activity was delected. Sediment in the feecsof Aspidochirolida has a higher organic content than thesediment grazed. Apparent dry matter digestibility ofsediment was -0.13. Increased organic content of feecsmay be due to selection of organic rich particles fromsediment and mucus produced to encase fecal pellets.

ACTIVITY AND METABOLISM OF

IIEMISQU1LLA ENS1GERA

(CRUSTACEA:STOMATOPODA) UNDER

HYPOXIC CONDITIONS.

JJ. Cassista* and D.L. Cowles. Field Studies

Institute, Newport Beach, Ca and Loma Linda

University, Loma Linda, Ca.

The predatory slomatopod Hemisquilla

ensigera was captured at 10-20 m depths and

transferred to artificial burrows in the lab under

a 10L:14D light-dark cycle. Burrow-capping

behavior and activity inside and outside the

burrow were monitored on a 24-hour basis using

lime-lapse video. Infrared lights were used for

observations within the burrow and at night.

Metabolic rates as a function of oxygen tension

were measured in respirometry chambers using

polarographic oxygen electrodes. This species

has a crepuscular foraging activity pattern. At

night the animals tended to be less active and

spent more time deep within the burrow.

Burrow capping occurred both during midday

and at night, during which time burrow oxygen

levels could potentially drop lo near zero. This

species is a near complete oxyconformer, so

aerobic metabolism is strongly depressed at low

oxygen levels, yet the animals remained active

within the burrow even under these conditions.

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488PARTICLE SURFACE ENERGY AFFECTSCAPTURE EFFICIENCY OF SUSPENSION-FEEDING MOLE CRABS (EMERITA TALPOIDA).S. Conova. Duke Univ., Durham, NC and Duke Univ.Marine Lab, Beaufort, NC.

Suspended paniculate matter varies in nutritionalcontent so it should be advantageous for suspension-feeders to be selective about what they eat. In caseswhere particles are captured by adhering to the Tiller, theadhesive force between particle and filter may be used topassively select some particles over others. I tested thishypothesis in two flow velocities with 15-25 umparticles of different surface energy and the secondantennae of Einerita taljyoida . Etiicrita talpoida fillerfood with Ihc antennae from the swash on high energybeaches. Particle surface energy affects adhesion lo theantennae at 5 cm/s and 30 cm/s. Particles with asurface energy of 20-30 dynes/cm were captured moreeffectively than particles with either lower or highersurface energies. This effect was more pronounced at 5cm/s than at 30 cm/s. The least effective paniclecapture rate at 5 cm/s was 50% of the most effectiveparticle capture rate, while at 30 cin/s the least effectiverale was about 75% of the most effective rate. Becauseparticle surface energy affects capture rale, theinteraction between the filter and natural particles withdifferent surface energies can provide animals with apassive method of food selection. This method will bemore effective when animals arc feeding in low velocityflows than in high velocity flows.

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489 490THE PRIMARY FUNCTION OF THEINTERCOSTAL MUSCLES IS LOCOMOTION.David R. Carrier. Brown University, Providence,RI 02912.

Lizards are unable to run and breathe at the sametime because their intercostal muscles assume alocomotor function during walking and running.To determine the phylogcnetic extent of thislocomotor role, I measured vcntilalory air-flowwith a mask-mounted screen pncumolach andactivity of the forth, fifth and ninth intercostalmuscles in four dogs walking and trotting on amotorized treadmill. During rest andthermorcgulatory panting, activity of the intercostalmuscles was associated with inspiratory andexpiratory airflow. However, during walking andtrotting, activity of these muscles was correlatedwith locomotion. Activity of the externalintercostals was associated with limb support bythe ipsilateral forelimb, and activity of the internalintercostals was correlated with the suspensionphase following ipsilateral front-support. Whenventilation and stride were not synchronized,activity of the intercostal muscles stayed locked tothe locomotor events but drifted in lime relative toventilation. Thus, the available evidence suggeststhat ventilatory activity of the intercostal musclesceases at the initiation of locomotion in both lizardsand mammals. These observations, combined withdata from the hypaxial muscles of walkingsalamanders, indicate that locomotion was theancestral function of the intercostal muscles.Support: NSF IBN 9258243 and 1BN 9306466.

DEVELOPMENT OF FEEDINGMORPHOLOGY AND BEHAVIOR INPLETHODONTID SALAMANDERS.S.M. Deban. Univ. of California, Berkeley.

Plethodontid salamanders with biphasiclife histories change their prey capturebehavior during development from suc-tion feeding to tongue prehension. Theprey capture behavior and feeding mor-phology were examined in four species ofplethodontid salamanders: Desmognathusquadramaculatus, Leuroenathusmarmoratus, Gyrinophiius porphyriticusand Pseudotriton ruber. The change inbehavior in each species is produced inpart by the dramatic musculoskeletal re-modeling that accompanies metamorpho-sis. Elements of the hyobranchial appara-tus and its associated musculature that areused for buccal expansion and suctiongeneration in the larva are remodeled toproduce tongue protraction and retractionin the adult. Some larval structures arelost at metamorphosis, while new featuresunique to plethodontids appear. Thesenovel features are associated with the

treat tongue protrusibility of pletho-ontids relative to other salamander taxa,

but may also represent a mechanical con-straint on the range of adult prey capturebehaviors.

491 492

FLIGHT VERSUS DISPLAY: THEFUNCTIONAL DESIGN OF AVIAN TAILMUSCLES.J.E. Kilpatrick* and S.M. Gatesy, Wake ForestUniv., Winston-Salem, NC.

In male turkeys (Mcleapris pallopavo') the tailhas two principle roles: flight and display. Inflight, rapid adjustments of tail fan size andposition modulate lift for control. However,during display the tail is elevated, fanned, andslowly oriented towards the female for prolongedperiods. These behaviors may impose conflictingdemands on the relatively simple tail morphology.We recorded tail muscle activity and kinematics infreely flying and displaying male bourbon redturkeys. High amplitude EMG's resemblingthose found in the pigeon, which are characteristicof twitch fibers, are observed during flight. Incontrast, preliminary data from these sameelectrodes reveal drastically decreased activityduring display, suggesting tonic fibers areinvolved. Male turkey caudal muscles maypossess mixed populations of tonic fibers (slowand economical) for display and twitch fibers (fastand expensive) for flight. Analysis of fiberhistochemistry will provide insight into a possiblephysiological compromise between flight anddisplay and its effect on the performance of thesebehaviors. (Supported by the WFU).

THE ORIGIN AND EARLY EVOLUTION OFTETRAPODS: NEW FOSSIL DATA AND THEIRINTERPRETATION.J. R. Bolt, J. A. Clack and R. E. Lombard.* The FieldMuseum of Natural History, Chicago, Univ. ofCambridge, Cambridge, UK, Univ. of Chicago,Chicago.

The earliest tetrapods (from the Devonian andMississippian Periods) have until recently been knownfrom sparse materials obtained at (ewer than twodozen geographically restricted sites. Paucity ofmorphological data, the small number of workers, anda frequently informal approach to character analysisand phylogeny reconstruction, have all contributed to apoor understanding of early tetrapod history. Recently,important new specimens have been obtained fromsome long-known collecting areas, while others havecome from newly discovered sites. These discoveriesare producing a flood of new morphologicalinformation.

We present the current results of an on-goingproject to express this morphological data in the formof cladistically informative characters. We introduce anelectronic database of characters that are applicable toearly tetrapods and to osteolepifocm fish, the likelysister-group of tetrapods. The database presentlycontains over 5000 potential character citations, fromthe literature and our own work. From this, we have lo-date developed more than 1000 working characters.

We present the protocols and format we employ indeveloping the characters, a suggested standardformat for character statements and phylogenetichypotheses based on some of these characters.

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493 494MODELING THE EFFECTS OF HEADMORPHOLOGY ON BURROWING EFFICIENCY INLIMBLESS VERTEBRATES: A CASE STUDY USINGAMPHISBAENIANS.P. M. Magwene, Committee on Evolutionary Biology,University of Chicago, Chicago, IL.Amphisbaenians are a group of limbless, burrowing

squamate reptiles (-140 spp.) which show a diversityof head morphologies (round-headed, spade-snouted, keel-headed, and others). Thebiomechanics of burrowing locomotion within this andother groups of limbless vertebrates is poorlyunderstood. To determine how head morphologyaffects burrowing, epoxy casts were made of twospecies of amphisbaenian, Rhineura floridana (spade-snouted) and Bipes canaliculatus (round-headed).These casts were attached to a force transducer anddriven into soils of different compactions. Work wascalculated from force-displacement curves. Theresults suggest that the spade-snouted form requiresgreater amounts of work to enter substrates with lowcompactions than does the round-headedmorphology. However, at higher soil compactions,the increased penetrative ability of the spade-shapedmorphology increases efficiency of penetration.These results provide a basis to begin to examinesome of the biomechanical and functional factorsunderlying observed ecological distributions amongamphisbaenians.

POPULATION VARIATION IN CALLCHARACTERISTICS AND LARYNGEALMORPHOLOGY IN CRICKET FROGS (ACRISCREPITANS).B.E. McClelland. University of Texas at Austin.

Intraspecific geographic variation in the spectraland temporal parameters of cricket frog advertisementcalls have been documented across the range of thisspecies in Texas (Ryan and Wilczynski, 1991, Biol. J.Linn. See. 44:249-271). I examined the morphologyof laryngeal components from 8 populations toassess possible geographic variation in the peripheralanatomy responsible for call generationcorresponding to variation in the acoustic parameters.I used paraffin embedded serial sections toreconstruct and measure the volumes of the followinglaryngeal components: arytenoid and basal cartilages,constrictor and dilator muscles and the vocal cords.All structures show population differences (Tukey'spost-hoc analysis) which, with the exception of vocalcord volume, were still apparent after correction forbody size variation (ANCOVA with snout-vent lengthas the covariate). Additionally, arytenoid cartilages,vocal cords, and dilator muscles show a clinalgeographic trend with larger larynges (relative to bodysize) in the west and smaller larynges in the east. Theintraspecific population variation and trends possiblyreflect compromises among differing selectionpressures including: the necessity for acoustictransmission clarity in the forested east, maintainanceof larger body sizes to prevent desiccation in the aridwest, and the demonstrated preference by femalesfor calls of lower dominant frequency. (Supported byNSF BNS-9021185 to W. Wilczynski and M.J Ryan)

495 496

NEUROMUSCULAR COMPARTMENTS INTHE planiarix lon^iis MUSCLE OF THEBULLFROG, Raim calcsbeiana.S.E. Peters Univ. of North Carolina at Charlotte,

Neuromuscular compartmentation, welldocumented in mammals, has been examined inonly a small number muscles in lower vertebrates.Compartmentation has been demonstrated in onlytwo amphibian muscles. To expand on this work,I used glycogen depletion to identify two neuro-muscular compartments in the planiarix longnx, thelarge ankle extensor of the bullfrog. Thesecompartments were about equal in size, stainingfor myofibrillar ATPase, «GPD and SDH showeda tiny population of tonic fibers, plus both type 1(FG) and type 2 (FOG) fibers. Little cleardistinction in relative distribution of these fibeitypes was found between the two compartments.Staining of the motor neurons in the spinal cordusing HRP showed little distinction between thepools from the two primary nerve branches. Thebullfrog had fewer motor neurons innervating PLthan have been found in the homologous musclesin mammals, suggesting a larger average ratio ofmuscle fibers per neuron This may relate to theballistic nature of hopping. These results call intoquestion a simple compartmentdl recruitment ofmotor units in this muscle.

VALVES AND ELASTIC FIBERS IN GIRAFFEJUGULAR VEINS ALLOW RAPID COMPLIANCEDURING EXTREMES OF POSTURAL CHANGE.T.H. Quinn, and J.W.Hicks. Creighton Univ., Omaha,NE, and University of California, Irvine.

Recent interest in the effects of posture and gravity oncirculatory system dynamics in long-necked animalsprompted us to more closely examine the morphology ofthe jugular vein in three specimens of Girqffacamelopardis. Sections were removed from the cranial,middle, and inferior portions of jugular veins and stainedeither with H&E or with Verhoeff-Van Giesson elasticfiber stain. Our initial studies indicate a much greatercomplexity than previously indicated. The elastic fibersin the vein wall are dense and randomly arranged in afeltwork at the cranial end of the vessel. Elastic Fibers inthe middle portion of the vein are arranged in lamina.Those of the interior (cardiac) end are similar to thosefound in the cranial portion of the vein. Thisarrangement may prevent collapse in the head upposition. The system of valves in the jugular vein wasalso studied. They are apparently analogous to the valvesin superficial veins of the quadruped limbs. We suggestthat the valves aid in the return of blood being "milked"toward the heart when the girall'e is in the head downposition. Tlie jugular vein of the giraffe provides anexcellent model for the study of the morphologicaladaptations of the vascular system to gravitationalstresses.

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497 498

THE MYOLOGY OF THE PALATE ANDPHARYNX IN MYRMECOPHAGID ANTEATERS.K.Z. Reiss. Cornell Univ.,Ithaca, New York.

The rayology of the elongatemyrmecophagid tongue deviates fromthe typical eutherian condition,but the extent of modifications inthe palatal and oropharyngeal mus-cles has not been directly address-ed. Specimens of Tamandua mexicanaand Cyclopes didactylus were fro-zen, sectioned on a bandsaw, anddissected. Homologies of muscleswere determined. Myrmecophagidsare members of the basal-most eu-therian clade ([Xenarthra + Pholi-dota]); some aspects of oropharyn-geal myology clearly representplesiomorphic eutherian character-i s t ics , when assessed with refer-ence to an outgroup, Didelphismarsupialis. Other aspects repre-sent apomorphies that are structur-ally correlated with 1) the forma-tion of the derived tongue and/or2) the caudad extension of the hardpalate and post-cranial position ofthe soft palate. This la t ter cond-ition is present in Tamandua (andMyrmecophaga) but not in Cyclopes.

MORPHOLOGY OF DEVELOPMENT OF RATMASTICATORY MUSCLES.I. SATO"1, K. SHIMADA* G. MURAKAMI^, H. EZURE',R. UENO'' andT. SATO VN ippon Dent. Univ., 'ShowaUniv., ^Nihon Univ., Tokyo, Japan

Morphology of the rat masticatory

muscles in the postnatal period (2 weeks),

was investigated by immunohistochemisry

and electrophoresis. In these stages, rat

masticatory muscles display myosin

electraphoretic patterns. Comparison with

myosins of these muscles allows.their

identifications. The collagen fibers of the

perimysium in each muscle formed complex

structures during development in contrast to

that of the endomysium. The variability in

myosin types and extracellular matrix form

may be indicated one of the important

elements during development in rat

masticatory muscles.

499 500

PRELIMINARY EXAMINATION OFHEPATO-SOMATIC INDICES IN SOME BATOIDELASMOBRANCHSR.L.Sherman*. D.S.Gilliam and R.E.Spieler.Nova Southeastern University OceanographicCenter, Dania, Fl.

Elasmobranchs use a variety of adaptations toenhance buoyancy, including reduced tissuedensity and large, lipid-rich livers. We examinedthe hypothesis that free swimming rays (Aelobatusnarinan, Rhinoplera bonasus) show largerhepato-somatic indices and reduced body densitythan demersal species (Urolophus jamaicensis,Dasyatis americana, Himantura schmardae,Rhinobatos lentiginosus). Hepato-somatic indiceswere: U. jamaicensis (n=i6) 3.4010.31(MearttSE); D. americana (18) 2.57±0.31; H.schmardae (2) 4.03±0.08; fl. lentiginosus (1) 1.18;A. narinari{1) 4.18; ft bonasus{8) 5.31±0.26.Hepato-somatic index for fl. bonasus wassignificantly higher than U. jamaicensis or D.americana (P<0.001). Preliminary water/air weightratios for U. jamaicensis and ft bonasus indicatethat their intact water/air weight ratios (X100) aresimilar(l/./amaicens/s3.16±0.25; fl. bonasus3.63±0.60). This comparison changed significantlyin eviscerated animals (U. jamaicensis 3.51±0.21;fl. bonasus 1.45±0.60). These results support theconclusion of others that body density is correlatedwith lifestyle in chondrichthyes.

EFFECTS OF TESTOSTERONE TREATMENT ANDCASTRATION ON FORELIMB MUSCLES OF MALELEOPARD FROGS, Rana pipiuns.C.A. Sidor* and D.C. Blackburn. TrinityCollege, Hartford, CT.

In some anuran species, the forelimb musclesexhibit strong sexual dimorphism, reflecting theirinferred roles in males during mating (amplexus).Our study examined the effects of castration andexogenous testosterone cypionate on the forelimbmuscles of overwintering, male Rana pi pi ens.Testosterone treatment stimulated markedincreases in mass and protein content of brachialadductors, forearm flexors, and carpal flexors, incomparison to muscles of placebo-treated controls.Forelimb extensors, retractors, and abductors wereweakly-sensitive or insensitive to hormonetreatment. Testosterone sensitivity of malemuscles correlated strongly with the degree ofsexual dimorphism. Castration did notsignificantly affect muscle mass or protein content,perhaps because the muscles were in seasonalregression. Protein content correlated stronglywith muscle mass, but protein concentration wasnot affected by experimental treatment. Thisstudy implicates androgens in the hormonalcontrol of sexual dimorphism of ranid forelimbmusculature.

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501 502STRAIN IN THE PIG TMJ DISC WITH PASSIVEMOVEMENT.BJ Sindelar* and SW Herring. University ofWashington, Seattle.

Relatively little is known about the in vivo function ofinlra-articular discs, such as that of the temporo-mandibular joint (TMJ). Even whether the disc servesprimarily as a compressive or a tensile element isdebated. The aim of this study was to measure the invivo linear displacements within the disc related topassive TMJ range of motion. Three female miniatureHanford pigs were surgically implanted with adifferential variable reluctance transducer (DVRT) intothe lateral aspect of the right TMJ disc. Priorcalibration testing indicated that the DVRT functionsessentially linearly for displacements of 0 to 3.5 mm.With the pig under inhalant anesthesia, the mandiblewas passively moved through all TMJ motions atvarious rates and amplitudes. Maximumdisplacements were measured at 1.037 mm foropening, 0.339 mm for left lateral deviation, 0.402 mmfor protrusion, and -0.134 mm for retrusion and rightlateral deviation. These recordings indicate that thedisc is subjected to tensile stresses in movementsrequiring anterior condylar translation (opening, leftlateral deviation, and protrusion) and to compressivestresses in movements requiring posterior condylartranslation (right lateral deviation and retrusion). Amaximum percent strain of 13% was calculated, whichfalls within the norms for biomaterials. Supported inpart by PHSDE 08513.

A TECHNIQUE FOR THE STUDY OF SINGLEJAW MUSCLE MOTOR UNITS.R. E. Druzinsky, Northwestern Univ., Chicago, IL.

Over the last 25 years, a wcallli of data has beengathered on the single unit properties of limb musclesbut, due lo their complex muscle architectures andinnovations via a cranial nerve, the properties of jawadductor motor units have still not been studied. Anew experimental protocol which allows stablepenetrations of axons of the trigcminal nerve in ratshas been developed. The rat is mounted in astercoiaxic frame and a large craniolomy is made onone side of the skull. The tendon of origin of thesuperficial masseter muscle is freed from thezygomatic arch and clamped in series with a load cell,and the mandible is rigidly fixed using a clamp thatgrasps the mandibular body anterior to the insertionsof the massclcr muscles. Glass micropipcttc clccrodesfilled with a solution of 3M KCI (12-20 Mil) arcdriven down through the nerve as it runs along (liefloor of (he cranial cavity, while passing small currentpulses through the electrode. When axons innervatingthe superficial massclcr muscle arc impaled, the actionpotential is recorded by the electrode, single unit EMGis recorded in the muscle, and twitch force is measuredby the load cell. To dale 13 superficial massclcr MUshave been stimulated in three rats. Stable penetrationshave been maintained for as long as 45 minutes andthe twitch tension of a small motor unit with a peaktension of I59mg (1.6 mN) can easily be isolated froma muscle that can generate 20 grams of twitch force.To our knowledge these arc Uie first measurements ofsingle MU lorces measured directly from the tendon ofa whole jaw adductor muscle.Supported by NIH DE05562 and NS528076.

503 504

The motor control conservatism .hypothesis statesthat the relative locations and positions of themotoneuron pools innervating homologous forclimbmuscles in vertebrates will remain conservedthrough evolutionary time despite the majormodifications in the anatomy of the limbs. Thishypothesis predicts that motor pool maps for birdsand terrestrial mammals should be similar forhomologous muscles despite the major differencesin the function and structure of their forelimbs.Here we present a preliminary test of thishypothesis. We used the retrograde neuronal tracerHRP to selectively label all the motoneuronssupplying seven major forelimb muscles in themouse (Mus musculusi: pectoralis, spinodeltoid,supraspinatus, infraspinatus, biceps, lateral triceps,and long triceps. The completed map was thencompared to Straznicky and Tay's 1983 map for thechick. In the mouse the biceps, spinodeltoid, andsupra and infraspinatus are positioned anteriorlywith respect to the remaining muscles studied. Inthe bird, the biceps pool is parallel to the pectoralisand triceps pools. In cross-section the maps of miceand birds appear more similar in the relative positionof the motoneuron pools. Preliminary data werealso obtained for the pectoralis and deltoid musclesin the little brown bat (Mvotis lucifugus) and thelizard (Anolis carolinensis). In the reptile the bicepspool is aJso positioned anterior to the pectoralis andtriceps pools lending tentative support to the motorcontrol conservatism hypothesis.

MECHANICAL PROPERTIES ANDARCHITECTURE OF THE SUPRACORACOIDEUSMUSCLE IN PIGEONS (COLUMBA L1V1A) ANDSTARLINGS (STURNVS VULGAHIS).S.O. Poore, A. Sdnchez-Haiman, A. Ashcroft, G.E.Goslow, Jr.* Brown University, Providence, RI.

In birds, the supracoracoideus, a bipinnate muscleof unusual morphology, plays a varying role in wingelevation during flapping flight. The supracora-coideus lies deep to the pectoralis, with its tendon ofinsertion passing through the triosseal canal andattaching on the dorsal aspect of the humerus abovethe glenohumeral joint. In the pigeon as well as thestarling, the muscle is composed of fast oxidativeglycolytic and fast glycolytic fibers. We studied thelength-active tension and length-passive tensioncharacteristics of this muscle and related them towing kinematics in two birds with contrasting wingloading and flight styles, the pigeon and starling. Weanesthetized adult birds (ketamine, 60mg/kg;xylazine, 6mg/kg) and surgically isolated themuscles' peripheral nerve and tendon of insertion.We attached this tendon to a transducer mounted ona rack and pinion and via supramaximal singlestimuli to the nerve (0.5ms duration) we measuredmaximal twitch contraction through the muscles'normal excursion range. The top of the ascendingarm of the length-active tension curve is coincidentwith the downstroke-upstroke transition for bothpigeons and starlings. In addition to elevation, thesupracoracoideus serves to rotate the humerus alongits longitudinal axis, an action that impactssubstantially on the muscles' role during flight.Supported by NSF grant IBN 9220097.


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505THE GENETIC ARCHITECTURE OF A SECONDARYCONTACT ZONE IN THE TIGER SALAMANDER(AMBYSTOMA TIGRINUM) COMPLEX.G.Z. Wurst', H.B.Shaffer and K.L. Rogers. Weber StateUniv., Ogden, UT, Univ. ot California, Davis, and LakeSuperior State Univ., Sault Ste. Marie, Ml

Recently, Shaffer and McKnight uncovered apreviously unrecognized contact zone between twodeeply differentiated mtDNA lineages of tigersalamandersin the San Juan Mountains of westernColorado. Using nuclear and mitochondrial markers, wehave exploited this unique opportunity to examine thedynamics of a known secondary contact zone. Basedon mtDNA markers, the newly discovered "San Juan"haplotype is widely distributed in western Colorado andeastern Utah, where it exists in pure populationssurrounded by the more widespread "Rocky Mountain"haplotype. At the eastern margins of the San Juanmountains, both haplotypes are found microsympatricallyin the same ponds. Based on multilocus allozymemarkers, these mixed populations conform toHardy-Weinberg expectations, suggesting that the twohaplotypes interbreed freely. Thus, during theirapproximately 1 - 2 million years of separation, noreproductive isolating mechanisms have evolvedbetween these lineages. We examined whether the"San Juan" haplotype represents the living descendantsof Ambystoma alamoensis. a species described fromPleistocene sediments from the nearby San Luis Valley.However, all specimens examined to date displayosteological characteristics of A., tiqrinum.

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The Crustacean Society

506 507EFFECTS OF ENVIRONMENTAL PARAMETERS ONDISPERSAL-RECRUITMENT MECHANISMS OFLARVAL AND POSTLARVAL DECAPOD CRUSTACEANSFROM THE CHESAPEAKE BAY, VIRGINIA ANDSURROUNDING OFFSHORE WATERS.L.A. Daugherty* and R.C. Maris.Mansfield University of Pennsylvania.

Vertical and horizontal distributionalpatterns of crab zoeae and megalopae aresignificantly affected by physicalvariables in their natural surroundings.Three stations were designated assampling sites based on estuarine, tran-sitional and offshore locations. Eachstation was sampled over a continuous 72-hour period with quantitative planktonsamples collected every 3 hours from 5depths [neuston (0.10-0.15 cm), 1 m, 3 m,6 m, epibenthos (11-13 m)]. Six disper-sal—recruitment mechanisms were esta-blished, with trends in dominant speciescorrelated with light, salinity, tempera-ture, wind, and tidal flow. Light con-tributes the dominant influence uponspatial and temporal positioning.

THE POPULATION ECOLOGY OF THELEPTOSTRACAN CRUSTACEAN NEBALIAPUGETTENSIS AT ELKHORN SLOUGH,MONTEREY BAY, CA.S.A. Gerken* and J.S. PearseUniversity of California, SantaCruz.

A study is currently underway toquantify the population ecology ofNebalia pugettensis on themudflats of Elkhorn Slough.Preliminary results show that thedensity fluctuates from a minimumof 6000 per square meter to atleast 36000 per square meter, thesex ratio is heavily skewed infavor of females, female size andbrood size may be related, and thesize distribution suggestsperiodic reproduction. Mating wasobserved in the lab, animalsbrooded for an average of 22.25days, and brood size averaged 39.4,although the range was very wide.In the field, brood size wassomewhat lower, averaging 27.3.

508MECHANISMS OF DIEL VERTICAL DISTRIBUTIONAND THEIR EFFECTS ON DISPERSAL-RECRUITMENTPATTERNS OF LARVAL AND POSTLARVAL DECAPODCRUSTACEANS IN THE CHESAPEAKE BAY,VIRGINIA AND ADJACENT AREAS.R.C. M a r i s * and L.A. Daugher ty .Mans f i e ld U n i v e r s i t y of P e n n s y l v a n i a .

Vertical positioning greatly affectsspat ia l and temporal distribution ofontogenetic stages of crabs and shrimps.Three stat ions were selected for 72-hrstudies based on proximity to an estua-rine location. Each s i t e was sampledevery three hours from neuston (0.10-0.15 m), 1 m, 3 m, 6 m and epibenthos(11-13 m). The collection, of 41species, 160 developmental stages andover 6 million specimens, was classifiedaccording to six dispersal-recruitmentmechanisms. Every mechanism involvedvariations in retention and expulsion withreinvasion. All patterns were s igni f i -cantly influenced by changes in dielver t ical distribution involving combina-tions of migration and maintenance amongthe developmental stages of differentspecies.


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Risk Sensitivity in Behavior

509 510A REVIEW OF RISK-SENSITIVE THEORYAND TESTS: USING JENSEN'SINEQUALITY TO CLARIFYEVOLUTIONARY ARGUMENTS.P.D. Smallwood. Bryn Mawr College, BrynMawr, Pennsylvania.

Risk-sensitive models of behavior wereintroduced to behavioral ecologists in 1980,spawning the development of a great deal oftheory by behavioral ecologists andpsychologists. Empirical investigations haveshown animals to be sensitive to differentlevels of variance in rewards, but very fewstudies have shown animals to switch betweenrisk-prone and risk-averse behavior in a wayconsistent with theory. Most studies findanimals to be inflexible in their response todifferent levels of variance. Explanations forthis inflexibile response to variance are oftenunclear about whether they regard theinflexibility as an adaptation or a constraint.Here, I review the different expressions ofrisk-sensitive models used by empiricists andtheorists, including the energy budget rule, Z-scores, and Jensen's inequality. I argue thatJensen's inequality is most useful in clarifyingarguments for evolutionary adaptation.

THE ANALYSIS OF BEHAVIOUR WITHVARIABLE OUTCOMES.A. Kacclnik. Department of Zoology, OxfordUniversity, Oxford UK.

Models and experimental analyses of behaviourfollowed by variable consequences include: Risksensitivity theory. Concerns slochasticily of outcomesand their varying value depending on the subject'scircumstances. Discounting. 1) Normative. Concernsvarying expected value of outcomes during the intervalbetween action and consequences cither because of theprobability of loss or because of "compound interests"effects. Most of these models predict exponentialdiscounting functions. 2) Self-Conlrol. An empiricalapproach concerning the subjective value of delayedoutcomes. Non linear discounting leads to strongeffects when the delay between action and outcome isvariable, regardless of stochaslicity. Experimentalresults support hyperbolic discounting functions. Ratemaximisation. Based on maximisation of die ratio ofexpected gains to expected involvement lime. Originalformulations were indifferent to variability, but presentdevelopments converge to the results obtained in self-control paradigms. Scalar Expectancy. A process-based approach that links cognitive models ofinformation processing to optimal foraging. Predictsproncness for delay variability and aversion for amountof reward variability. I shall discuss theinterconnections between these frameworks and prcscnldata relevant to all of them.

511 516

EXPONENTIAL VERSUS HYPERBOLICDISCOUNTING OF DELAYED OUTCOMES.L. Green and J. Myerson, WashingtonUniversity, St. Louis, MO.

Animals make many choices that havedelayed consequences, the value of whichdecrease with delay. An important questionfor models of behavior concerns what kind ofrule best describes how the value of delayedoutcomes is discounted. Two types of ruleshave been offered in the economic andpsychological literatures — exponentialdiscounting and hyperbolic discounting.Exponential discounting assumes a specificmodel of the risk involved in waiting fordelayed outcomes, whereas hyperbolicdiscounting follows from a different model ofsuch risks, although other derivations arepossible. Previous studies appeared topreclude exponential discounting but, as wewill show, the issue is resurrected by ourrecent finding that discounting is dependenton outcome magnitude. Moreover, thequestion must be resolved by analysis ofindividual behavior, not group averages, andsuch analyses will be presented.

RISK-SENSITIVITY AND THE PARADOX OFCOLONIAL WEB-BUILDING IN SPIDERSG.W. Uelz. Univ. of Cincinnati

Group foraging Is rare in spiders,occurring only where prey availability ishigh. If colonial web-building increasesindividual prey capture rates as shown, whydoes group foraging not occur more oftenwhere prey are scarce? Risk-sensitivity mayexplain this paradox, as variance in preycapture is reduced in groups; spidersshould be risk-averse and join groups onlywhen prey exceed a threshold level. Fieldstudies show that group foraging varies aspredicted between species, populations of asingle species, and sites within a population.However, recent models suggest thenecessity of examining variance withinindividuals over time rather than amongindividuals within populations. Additionally,mechanisms responsible for variancereduction in colonial webs may be lesseffective than previously assumed. Newfield data suggest that while variation inprey for individual spiders over time may besomewhat less in groups than for solitaries,the relationship between colonial web-building and variance in prey capture is farmore complex than originally thought. TheInfluence of risk-sensitivity on reproductivesuccess and the evolution of colonial web-building will be discussed.

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Risk Sensitivity in Behavior

518FUTURE PROSPECTS FOR RESEARCH ON RISK-SENSITIVITY IN ANIMAL BEHAVIOR.L.A. Real, Indiana Univ., Bloomington

Research on risk-sensitivity has ,spawned a rich and diverse literaturerepresenting a variety of approaches andperspectives. There are some clearfuture directions which eminate fromeach of these avenues of development. Iwill outline and illustrate what I feelare the three major new directions inrisk-sensitive research and how thesenew areas should be developed. The firstarea relates to the cognitive andpsychological mechanisms involved ininformation-processing in variableenvironments. The second relates to theecological context of choice underuncertainty and the extension of labora-tory studies into natural field condi-tions. The third relates to the develop-ment of new theory and empirical testswhere choices involve the actions ofother foragers departing from thetraditional single decision-maker modelsof choice.


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Phylogenies and Comparative Biology Stage II:Testing Hypothesis Derived from Phylogenies

520 521TESTING PATTERN AND PROCESS PREDICTIONSOF SEXUAL DIMORPHISM IN SOUTHEAST ASIANFROGS.S.B. Emerson, Univ. Utah, Salt Lake City

Recent work has centered on the ori-gin and evolution of an unusual suite ofsexually dimorphic features in the genusRana. First, a phylogenetic hypothesisof relationship was constructed for thespecies from morphological and moleculardata. Second, this hypothesis was usedto make a series of testable predictionsregarding the proximal physiologicalprocesses controlling the expression ofsexually dimorphic traits. The coin-cident cccurence of parental care andthe loss of secondary sexual charactersin the basal species of the clade sug-gest that members of this group mayhave unusual androgen levels and maleparental care. Third, these predictionswere tested using ecological, morpholog-ical, and endocrinological data. Atleast one derived member of this cladeis characterized by low androgen levelsand male parental care.

THE EVOLUTIONARY HISTORY OF AFEMALE PREFERENCE.A.L. Basolo, University of Nebraska-Lincoln.

In Poeciliid fish, males exhibit a range of caudalfin modifications; in several groups, males possesscolored extensions of some caudal rays. Theseextensions are not homologous; they are comprisedof different fin rays and pigment types. It thusappears that similar traits arose independently in theevolutionary history of Poeciliids. A possibleexplanation for the evolution of these convergenttraits is that a primitive preexisting bias (preference)has favored similar traits in different lineages. Inone group, Xiphophorus. which contains platyfishand swordtails, female green swordtails prefermales with long colored extensions called swords.Female platyfish (X. maculatus and X. variatus)prefer conspecific males with artificial swords eventhough males of these species do not have swords.Because of the presence of conflicting phylogenies,it is unclear whether swordlcssncss is the primitivestate for Xiphophorus. However, it is likely thatthe sword is unique to Xiphophorus. Females ofthe sister group to Xiphophorus. Priapella. whichlack swords, prefer conspecific males with artificialswords; thus, it appears that a bias favoring swordsevolved prior to the sword itself. Current work isexamining other groups of Poeciliids to determinewhether a shared primitive bias can account for theevolution of the different caudal fin types exhibitedby other lineages.

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Animal Behavior

528 529

NAVIGATING UP AN ODOR PLUME:C O M B I N E D R H E O T A X I S ANDCHEMOTAXIS.N.D. Pentcheff*, C.M.Finelli, D.S.Wetfiey, andR.K. Zimmer-Faust. Univ. of South Carolina,Columbia.

Finding the source of an odor plume iscritical to the success of many important animalbehaviors (e.g., location prey or mates). Anodor plume is created when a chemical givenoff by an odor source is transported downstreamby fluid flow in the environment. Navigation upan odor plume, therefore, could be controlledby measurement of the chemical stimulus itself(chemotaxis), measurement of the flow direction(rheotaxis), or a combination of both. In tidalchannels, blue crabs (Callinectes sapidus)navigate up odor plumes using a combination ofrheotaxis and chemotaxis, based on both fieldand laboratory investigations. Rheotaxis directsmovement upstream towards the odor source.Chemotaxis directs movement lateral to the flowdirection, maintaining alignment with the odorplume. This mechanism differs from thatdiscovered in other well-studied systems(notably male moths seeking females) as aresult of hydrodynamic differences betweenenvironments.

HONEYBEE FLOWER CONSTANCY: BEHAVIOR IN" THEGAMES KE IXVIT.E THEM TO FLAY. P .S . H i l l * ,P.H. We]Is, and H. Wells . Univ. of Tulsa,Univ. of Oklahoma, Norman and OccidentalCol lege, Los Angeles.

When presented with an a r t i f i c i a lflower patch of both blue and yellowpedicellate flowers, free-flying honey-bees became individually constant to oneof the two flower morphs, irrespective ofreward quality or quantity. In a totalof 3020 visits, bees failed to choose theflower color on which they first landedonly 17 times. A simple change inmethodology elicited greatly differentresults. Eleven new bees were presentedwith a patch of flowers each painted halfblue and half yellow. The same beescontinued to visit when the patchcontained only blue flowers (2M sucrosereward), and again when the patch was ofonly yellow flowers (1M sucrose reward).When finally given simultaneouslyrewarded choices of both yellow (1M) andblue (2M) flowers, 5 of the bees wereconstant to yellow, 5 became blue-constant, and one visited both colorsrandomly.

530 531

HONEY BEE (APIS MELLIFERA) USE OFFLOWER FORM AND PIGMENTPATTERNS IN MAKING FORAGINGCHOICES.H. Wells*. J. Lamb, J. Petrikin, and P.S. Hill.University of Tulsa, Tulsa, Oklahoma.

Honey bee forager use of flowershape (three-dimensional form) and pigmentpattern on flowers (patterns) were examinedin the context of a repetitive decisionprocess of flower choices within a flowerpatch. All experiments used artificial flowerpatches. Experiment I examined formdifference utilization (Horizontal 2D versusVertical 2D versus L-shape 3D), whileExperiment II examined pigment patterndifference utilization (Bilateral versusRadial). When rewards were identical inflower morphs bees foraged randomly.When rewards differed between flowermorphs, bees utilized flower three-dimensional form in Experiment I and flowerpigment pattern in Experiment II to restrictflower visitation to the morph offering thegreater caloric reward. Forager error rate,however, was approximately three times thatobserved when a simple color dimorphismexisted.

CARPENTER BEE (XYLOCOPA HICANS) FORAGERSFAIL TO DEMONSTRATE RISK-SENSITIVITY INBINARY CHOICE EXPERIMENTSS.M. Perez and K.D. WaddingtonUniversity of Miami

Carpenter bee foragers chose betweentwo types of a r t i f i c i a l f lowers,"constant" and "va r iab le " , that offeredthe same expected reward but d i f fe ren tvariances. In one experiment, variance innectar volume d i f fe red between the twoflower types; in the other experiment,variance in nectar sugar concentrationd i f fe red . Foragers were tested under bothhungry and wel l - fed condit ions. Resultssuggest that indiv idual carpenter beesare indifferent to variabi l i ty in bothnectar volume and nectar sugar concentra-tion. Forager risk-indifference wasunaffected by hunger. These resultscontrast with those of bumble bee risk-sensitivity studies in which the bumblebees experience a higher expected rate ofnet energy gain from the constant flowertype. Carpenter bees may not discriminatebetween the constant and variable flowertypes because, for them, the flower typesdo not differ in expected rates of netenergy gain.

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Animal Behavior

532PHYLOGENETIC RELATIONSHIPSWITHIN THE GENUS BRACHYRHAPHIS ASINFERRED FROM MITOCHONDRIAL DNASEQUENCE DATA.C.L. Mojica* and A. Meyerl. University ofCalifornia at Berkeley; State University of NewYork ill Slony llrook.

The relationship!) within the Uamlmsiiiiiand within the genus Brachyrliaphis (Regan1913) are explored using a partial sequencefrom the mitochondrial gene for cytochrome b.Tribal relationships hypothesized by previousworkers and the monophyly of the genusBrachyrliaphis are supported by parsimony anddistance methods. The black color pattern ofthe anal fin/gonopodium, a character unique tothis genus, is present in the basal species and islost once in B. hartwegi. Morphological,behavioral and ecological correlates of this colorpattern will be discussed.

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533 534VIABILITY AND REPRODUCTIVECOMPETENCE OF MALE AND FEMALECHANNEL CATFISH WITH YY SEXGENOTYPE.K.B. Davis*, B.A. Simco and C.A. Goudie. TheUniversity of Memphis, TN, and USDA/ARS,Catfish Genetics Research Unit, Stoneville, MS.

Channel catfish females are homogametic(XX) for sex determination , althoughmorphologically distinct sex chromosomes havenot been described. Previously verified XYfemales and YY males were mated with eachother and produced all male progeny; thegenotypic composition was expected to beXY:YY. Feminization of these males wasaccomplished with 100 mg/kg 17a-ethynyltestosterone . When males from thispopulation were mated with XX females, threespawns produced only male progeny,demonstrating the YY sex genotype of the maleparent. When females from this population weremated with XY males, six spawns werecomposed of only male progeny, demonstratingthe YY sex genotype of the female parent.Remaining spawns were 3:1 malesfemales,indicating an XY maternal genotype. Thus, thefeminized YY sex genotype in channel catfish isviable and reproductively competent.

EFFECTS OF TEMPERATURE ONMULLERIAN DUCT REGRESSION INTURTLE WITH TSD.T. Wibbels*, C. Wilson, and D. Crews.Univ. of Alabama at Birmingham andUniv. of Texas at Austin.

The effects of temperature onmullerian duct development andregression were examined in a turtle,Trachemys scripta, with temperature-dependent sex determination. In aninitial study, the chronology of mullerianduct development and regression wasexamined at male and femaletemperatures. Mullerian duct regressionwas noticeable at male-producingtemperature by approximately stage 21and was distinct by stage 22, whereasmullerian ducts continued to proliferateat female-producing temperaturesduring these stages. In temperatureshift experiments the mullerian ducts ofmale embryos regressed regardless ofthe incubation temperature duringstages 21 through 26.

535 536

PLASMA STEROID CONCENTRATIONSDURING THE BREEDING SEASON IN ADESERT SPADEFOOT TOAD, SCAPHIOPUSCOUCHII.L. A. Harvey, S.K. Woodley, M.C. Moore, andC. R. Propper. Northern Arizona Univ., Flagstaffand Arizona State Univ., Tempe.

To investigate the reproductive pattern utilized bya desert anuran, we determined plasma steroidconcentrations in male and female Scapliiopuscouchii during July and August of 1993. Bloodwas collected from both sexes in pre-breeding,calling (males only), amplexing, and post-breedinganimals. In males, plasma levels of testosterone(T), dihydrotestosterone (DHT), and corticosterom(B) were determined using RIA. For females,plasma steroid concentrations were determined forT, DHT, B, estradiol (E2), and progesterone (P).There were significant differences in steroid levelsamong males in the four groups, with calling andamplexing toads showing the highest levels of T,DHT, and B. In females, significant differenceswere found among groups for plasma levels of E2,P, T, and DHT. Progesterone was highest inamplexing females, while E2 and DHT werehighest in pre-breeding and amplexing females.Post-breeding animals had lower T levels than inother groups. There was no significant differencein B among female groups. These results suggestthat this species exhibits an associated pattern ofreproduction with regards to plasma sex steroidconcentrations and reproductive behavior.

CHANGES IN BRAIN GnRH ASSOCIATED WITH AB-SOLUTE AND RELATIVE PHOTOREFRACTOR1NESSIN HOUSE SPARROWS, PASSER DOMESTICUS.T.P. Halm* and G. F. Ball. Johns Hopkins University, Bal-timore, MD.

Temperate zone birds terminate reproduction when theybecome pholorefractory. In many species, refractoriness is"absolute" in that gonadal regression occurs before daylength declines, and individuals arc reproductively unre-sponsive even to continuous light. Based on studies of a fewspecies, this form of refractoriness appears to be associatedwith a reduction (compared with breeding and/or photosen-sitive birds) in numbers of hypothalamic cells and fibers thaiare immunorcactivc for gonadotropin releasing hormone(GnRH). Some species display "relative" refractoriness, inthat day length must decline before gonadal regression oc-curs, and individuals never lose the capacity to respond tcvery long days. A few reports suggest that GnRH levels inthe brain do not change during relative refractorinessHouse sparrows regress their gonads under natural condi-tions when day length declines during summer (they appealto be "relatively" rcfractoiy). but if held on long days the)eventually regress the gonads despite no decline in pholopc-riod (they appear lo be "absolutely" refractoiy). In this ex-periment with adult male house sparrows, we tested whcthcigonadal regression based on "absolute" versus "relative" re-fractoriness reflected similar changes in hypolhalamicGnRH. We used immunocytochcmisliy (primary antibod)sensitive to both forms of avian GnRH) to compare the dis-tribution and number of GnRH-immunorcaclivc cells and fi-bers among reproductively active individuals on long days,"absolutely" refractory individuals on long days, and"relatively" refractory individuals induced to regress byshortened days. Preliminary analysis shows similar disap-pearance of GnRH inimunorcnclivc cells and fibers in bothgroups of refractory birds compared with birds still inbreeding condition. Thus, mechanistically, house spamm*;IJ> become "absclulcl> refractor)," irrcspcclhc of t!.cphoto-regime used to induce refractoriness.

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VOLUMETRIC CHANGES IN THE SONGCONTROL NUCLEI OF AMERICAN TREESPARROWS ON DIFFERENT DAY LENGTHS:WHAT IS THE ROLE OF TESTOSTERONE?G.F. Ball*, D.J. Bernard and F.E. Wilson.Johns Hopkins University, Baltimore, MD andKansas State University, Manhattan

In several songbird species, birds housed on longdays, characteristic of Spring, have larger songcontrol nuclei than do birds housed on short days,characteristic of Fall. We attempted to establish iftestosterone (T) of gonadal origin is solelyresponsible for these changes in the song system,or if photoperiod influences this systemindependently of gonadal T. The volumes of 3song nuclei (HVC, area X, and RA) and 1 controlnucleus (SPM) were measured in both intact andcastrated male American tree sparrows in each of 3reproductive states: short-day photosensitive;long-day photostimulated; long-dayphotorefractory. All 3 song nuclei were largest inintact photostimulated males. Castratedphotostimulated males and intact and castratedphotorefractory males had larger song nuclei thandid either intact or castrated short-dayphotosensitive males and did not differ from eachother. SPM volume did not differ among thegroups. These data suggest that both T-dependentand T-independent mechanisms associated withlong days influence song control nucleus volume.

TESTIS SIZE, PLASMA TESTOSTERONECONCENTRATIONS, AND MALE-MALEAGGRESSION DURING THE ACTIVESEASON OF ARCTIC GROUND SQUIRRELS.B.M. Barnes* and C.L. Buck. University ofAlaska, Fairbanks.

Male arctic ground squirrels {Spermophilusparryii) from a marked population in theBrooks Range were repeatedly live-trapped,weighed, assessed for % body fat viaTOBEC, and sampled for blood and gonadalstate over their active season from April toSeptember. Plasma from blood was assayedfor testosterone (T) via RIA. Large andspermatogenic testes in late April regressedbefore June and remained regressed for thecrest of the active season. Plasma T levelswere maximal in spring after emergencefrom hibernation and, unexpectedly, highagain in late summer. Male-male aggressivebehavior was assessed by placing a cagedmale nearby the burrow of another male andthen recording the target male's behavioraround and attentiveness to the intruder. Inboth spring and fall target males actedaggressively towards the caged males. Inspring, however, this behavior may requirethe simultaneous presence of a female. Highspring and fall circulating levels of T maysubserve male-male aggression, but to dif-ferent ends: reproductive behavior in springand territory and cache defence in fall.

539 540

BIOBEHAVIORAL AND NEUROENDOCRINECONSIiQUENCHS OF SEPARATION STRliSS.W.L.R. Castro', and K.S. Matt. Arizona StaleUniversity, Tempe.

Siberian dwarf hamsters (Phodopus suncorus)form strong pair bonds and disruption of the pairresults in alterations in behaviors, and brainneurotransmitters. We examined the effects ofseparation stress on the neuroendocrine responseto an intruder male. Results from behavioralanalysis indicate that separated males showdecreases in fighting, attacking, biting (p< .02),chasing (p< .03), and increases in attack latency(p< .05). Separated animals, also showed adecrease in plasma levels of norcpinephrine(p < .05), epinephrine (p < .02) and testosterone(p<.03) following the encounter. However, bothgroups showed a significant increase in cortisol inresponse to the intruder (p< .0001). Inconclusion, chronic stress induced by a separationparadigm causes downregulation of thesympathetic nervous system, and downstreaminhibition of reproductive system. Furthermore,there are behavioral alterations which may be aconsequence of direct effect of stress on thecentral nervous system or an indirect effect of thehormonal changes.

Er-hfcC IS OF SEX STEROIDS ON SEXUALBEHAVIOR IN THE BIG BROWN BATM.T. Mendonca", S.D. Chernetsky, K.E.Nester and G.L. Gardner. Auburn University,AL

Vespertilionid bats exhibit a dissociatedpattern of reproduction. This patternsuggests that sexual behavior isindependent of sex steroids and moredependent on direct environmental cues.Male and female big browns were collectedin Butler Co., AL in the falls of 1992 and1993 to determine if mating activity isdissociated from sex steroid levels. Animalswere either not manipulated (INTACT) orgonadectomized (GON-X). Males were alsoGON-X and given testosterone (GON-X+T).In Jan-Feb, 1993, mating activity among theINTACT, GON-X.GON-X+T male groups didnot differ significantly in staged trials. GON-Xfemales mated significantly more thanINTACT females in these tests. In the flightcage observations, INTACT males matedsignificantly more than GONX males;INTACT and GON-X females did not differ. In1994, almost no individuals of any groupmated. 1994 winter temperatures differed inpattern from those of 1993 suggesting agreater influence by temperature than bysteroid manipulation on sex behavior.

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SEASONAL CHANGES IN GONADALCONDITION AND TESTOSTERONELEVELS, IN THE MALE BIG BROWN BAT,EPTESICUS FUSCUS.G. L. Gardner* and M. T. Mendonga. AuburnUniversity, Auburn Al.

Two wild populations, one in Auburn, LeeCo., Al. and the other in Georgiana, ButlerCo., AL, were sampled from June 1993 toNovember 1993 to determine the pattern ofreproduction in a southern population ofmale Eptesicus fuscus. Monthly bloodsamples were taken upon capture from 10males to determine circulating levels oftestosterone. Surgery was performed on thesame males to obtain testis volume and todetermine the stage of spermatogenesis bybiopsy. In early July there is minimalspermatogenic activity as onlyspermatogonia are observed. Peakspermatogenic activity occurs in Septemberwith full regression by the first of November.Circulating levels of testosterone will also bediscussed. These data show at least a onemonth lag in timing of peak spermatogenesiscompared to that found for northernpopulations.

TESTOSTERONE IMPROVES EXERCISEENDURANCE IN A LIZARD (ANOLIS SAGREJ).H.B. John-Alder*. Rulgcrs Univ. New Brunswick.

We have reported that exercise endurance (EE) canbe modulated by changes in a lizard's socialenvironment and that this modulation is probablymediated in part by androgens. Here we report thatEE is improved substantially by exogenoustestosterone (T). Adult male Anolis sagrei weresubjected to bilateral castration (C), castration plus aSilastic® T implant (T), or sham-surgery (SH). EEwas measured as maximal running lime at 0.3 km/h,32^2 twice prior to surgery and twice 30 d later.Plasma T differed significantly among groups at theend of the experiment (C: 1.1+0.23, T: 60.1+7.65,SH: 7.9+4.55 ng/ml; p<0.001). Kidney mass,which is responsive to T, was significantly smaller inC than T and SH (p<0.001). EE, which wasindependent of mass in our sample, increased from321+29.8 to 518+88.3 s in T (p=0.03) but did notchange in C (275+44.2 to 273+48.8 s) or SH(273+17.5 to 307+51.5 s). Body mass increasedsignificantly (p<0.01) during the experiment in T andSH but not C. Heart muscle mass was greater in Tthan in C (p=0.003) or SH (p=0.026), independentof differences in body mass. These results indicatethat T improves EE in A, sagrei in part by stimulatingcardiac hypertrophy, which would be expected toincrease 62 delivery to working muscle. Additionaldata on skeletal muscle morphology and intermediarymetabolic enzyme activities will be presented.Supported by the Charles and Johanna Busch Fund.

543 544

RELATIVE BODY MASS BUT NOT FAT-BODY AND LIVER MASSES DIFFERBETWEEN MALE REPRODUCTIVEALTERNATIVES OF THE TREE LIZARD.Diana K. Hews* and Michael C. Moore.Arizona State University, Tempe.

In some vertebrate species, males vary inbehavior and morphology important in reproduc-tion. Tree lizards (Urosaurus ornatus) have twodevelopmental^ fixed male morphs: territorial(Orange-Blue throat color, OB) and nonter-ritorial (Orange throat color, O) males.Although mean snout-vent length (SVL) of Omales is greater than that of OB males, in thisstudy we found that OB males have greater bodymass (relative to SVL) than O males, both asjuveniles and as adults. Further, in adults neitherrelative fat body mass nor relative liver massdiffer between male morphs. This suggests theyet untested hypothesis that muscle mass maycontribute to morph differences in body mass.The morph difference in relative body mass isintriguing because in other vertebratestestosterone (T) often increases muscle mass butcurtails long-bone growth, and previously wefound that increased T in hatchlings producedOB males but castration produced O males.

A NON-INVASIVE METHOD FORSUSTAINED ELEVATION OF STEROIDHORMONE LEVELS.R. Knapp* and M.C. Moore. Arizona StateUniv., Tempe.

We describe an inexpensive method for non-invasively elevating steroid hormone levels inlizards for periods of greater than 24 hours. Ourmethod involves applying sesame oil containingthe hormone onto a dermal patch which is thensecured to the animal's back using a transparentadhesive dressing. We have used these patchessuccessfully to elevate corticosterone levelswithin a physiological range in both laboratory-housed and free-living tree lizards (Urosaurusornatus) for at least 24 hours. Hormone deliverywas found to be steady over a period of 6-24hours following application of the patch asmeasured by circulating plasma levels ofcorticosterone. Progesterone and testosteronehave also been successfully administered usingthese patches in our laboratory by D.K. Hews.This method should be useful for behavioralendocrinology studies in a variety of reptiles. Itshould also be adaptable to any species wherecontact between the patch and the integumentcan be maintained via the transparent adhesivedressing.

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THYROID REGULATION OF GROWTH AND FOODCONSUMPTION IN THE LIZARD, Sceloporusundulatus. R. Gerwien* and H.B. John-Alder. RutgersUniv., New Brunswick, NJ.

Successful growth regulation forces an animalto achieve a balance between the presumed fitnessadvantage and the energetic cost of rapid growth.Our ultimate goal is to understand how an animal'sthyroid axis helps to integrate information aboutenergy status with energy dependent processes such asgrowth. We previously reported that thyroidregulation of growth in lizards may be mediatedthrough changes in foraging behavior. The purpose ofthis study was to investigate the relationshipsbetween thyroid status, growth rate, and foodconsumption. Lizards were assigned either to surgicalthyroidectomy (Tx) or sham-surgery (Sh), followedby thyroid hormone (or placebo) replacement threeweeks later. Growth rate and food consumption weremonitored for the duration of the experiment. Sham-operated lizards grew faster (snout-vent length:p=0.003, body mass: p=0.015) and ate more crickets(p=0.003) than Tx lizards. Individual variation involuntary food intake explained only about 28% ofthe thyroid effect on growth r.ile (p=().(XO).Thyroxine replacement increased growth in terms oflength (p<().O()l) but not mass (p=0.276) in both Tx andSh when compared to placebo-implanted controls.However, food consumption did not differ among these4 treatment groups (p=0.173). This studydemonstrates that > 70% of thyroid-dependenteffects on growth is independent of alterations in foodintake. Supported by NSF DEB 87-02490.

THYROID ONTOGENY OF ALTRICIALSTARLINGS AND THE EFFECTS OF FOODRESTRICTION IN ALTRICIAL STARLINGSAND PRECOCIAL QUAILW. A. Schew and F. M. A. McNabb*, Univ.Pennsylvania, Philadelphia and VirginiaTech, Blacksburg.

Plasma thyroid hormones (THs) werestudied in altricial starlings during lateembryonic life and 20 days posthatch. BothT4 and T3 were very low in embryos. Afterhatch plasma T4 increased steadily from d1to d10-12 (approx. 6X increase), thendeclined. Posthatch plasma T3concentrations were >2X those in embryosand increased slightly during the first 10-12d.These patterns are similar to those in ringdoves, the only other altricial species inwhich thyroid ontogeny has been studied.Plasma TH concentrations of Japanese quail,in which thyroid development occurs muchearlier than in starlings, were similar to thosereported previously. Food restricted chicks,on a weight maintenance regime starling atd3, did not show the increase in plasma THsthat occurred in growing controls of bothstarlings and quail. Plasma THs returned toconcentrations comparable to those incontrols of the same age within a few daysafter chicks resumed ad lib feeding.Supported by a grant from Am. Ornith. U.

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EXPRESSION OF AMPHIBIAN BRAINTIIYROTROPIN-RELEASING HORMONE ANDARGININE VASOTOCIN RECEPTOR GENES INXenopus lacvis OOCYTES. C.L. Mitchell*, J.S. Hosier,H.E. Esch and S.K. Boyd. Univ. of Notre Dame, IN.

Brain receptors for TRH and AVT have not been wellcharacterized in non-mammalian vertebrates, although bothhave numerous CNS effects. We expressed amphibian brainTRH and AVT receptors by injecting Xenopus oocytes withbrain whole niRNA, then voltage clamping cells to monitortransmembrane current flux in response to ligand. Injectedoocytes responded to TRH, TRH free acid, cyclo-(his-pro),[3-MeHis!)TRH and AVT, as indicated by inward mem-brane currents. Response was specific, since mRNA-injected cells showed no response to isotocin, and water- oruuinjcclcd cells showed no response to any neuropeptides.TRH response was reversible, dose-dcpcndcnl, and satura-blc. Time course of response to maximally effective liganddoses was consistent, and latency and response time werecharacteristic of agonist applied. Time course differencessuggest that the amphibian brain expresses more than onesubtype of TRH receptor. V, vasoprcssin receptor antago-nist dfCUjMryrtMc^lAVI' did not alter response whenadded to cells already maximally stimulated with AVT.Alone, however, it produced a gradual current flux whichwas increased by secondary application of AVT. Themammalian antagonist thus has agonistic effects in thissystem. Unique receptors for TRH and AVT are encodedin Xenopus brain; our data mark the first expression ofthese receptors from a non-mammalian vertebrate.

IN VIVO AND IN VITRO EFFECTS OFGONADOTROPIN-RELEASING HORMONEON PROLACTIN IN THE TILAPIAOREOCHROMIS MOSSAMBICUS.G M . Weber*, RJ . Borski, JFF. Powell, NM.Sherwood and E.G. Grau. Univ. of Hawaii,Honolulu; Univ. of Michigan, Ann Arbor and Univ.of Victoria, Victoria.

The objective of this study was to examinethe role of GnRH as a regulator of PRL in thetilapia, Otvochmmis mossambicus. The release ofboth endogenous forms of PRL, IPRL188 andtPRL177, from the rostral pars distalis wasstimulated by GnRH within 2 min and wasaccompanied by an increase in intracellular C a + + ,determined by FURA 2 studies. Three forms ofGnRH native to the tilapia stimulated PRL releasein 20 hr cultures with Chicken II-GnRH having thegreatest potency, followed by Salmon-GnRH andSea Bream-GnRH respectively. GnRH stimulationof PRL release was potentiated by estradiol-17B andtestosterone in 3 hr cultures. Intraperitonealinjections of LHRH analog (LHRHa) (0.1 ug/gbody weight) increased serum levels of the PRLs inboth male and female tilapia within 1 hour ofinjection. Serum levels of the PRLs were elevatedat 2 days after intramuscular implantation ofLHRHa cholesterol pellets (025 ug/g body wt.).Supported by NSM Grant DCB 91-04494 andNOAA/Sea Grant No. NA36RG05O7/R/AQ-37 toE.G.G.

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549 550EFFECT OF AMMONIA ON CENTRALBIOGENIC AMINES IN THE FATHEADMINNOW Pimephales promelas.Patrick J. Ronan', Mark Gaikowski, John M.Matter and Cliff H. Summers. University of SouthDakota, Vermillion SD, US Fish & Wildlife Serv.

Ammonia is a toxin with endogenous andexogenous effects in aquatic species. Exogenousammonia in concentrations over 20 uM is lethal foradult fathead minnows. Although unionizedammonia passes freely across the gills and is toxicto all tissues, very little is known about the effectsof this agent on central neural systems. Adult (N =120) fatheads were placed in water with 6 differentconcentrations of ammonia from 0.13 \iM to 18uM. Brains were dissected rapidly on ice and thenfrozen at -80°C. Whole brains were analyzed byelectrochemical HPLC. NE, Epi, DA, and 5-HTlevels were depleted by increasing ammoniatreatment. At lower concentrations, serotoninprecursor (5-HTP) production was higher; thereforeserotonin production may also be higher.Metabolite levels for all systems appear to beunchanged. Ammonia may effect neurotransmittcrsystems by affecting production of transmittersrather than affecting release and metabolism.

CORTICOTROPIN-RELEASING HORMONE FUNC-TIONS AS A NEUROENDOCRINE MEDIATOR OKENVIRONMENTALLY-INDUCED ADAPTIVE PLAS-TICITY IN AMPHIBIAN METAMORPHOSIS. Robert J.Denver. The University of Michigan, Ann Arbor.

I have proposed lhat dcterioralion of the larval habitat ofsome anuran amphibians functions as a 'strcssor' whichaccelerates development and that this response is controlledby classical vertebrate neuroendocrine stress pathways (R.J.Denver, Gen. Comp. Endocrinol. 91:38-51). Corticotropin-releasing hormone (CRH) is a potent stimulator of thyrotro-pin (TSH) secretion in frogs. Several CRH-like peptidesincluding sauvagine (SV) accelerated development of lad-poles of Scaphiopus hammondii when injected on alternatedays beginning 18 days after hatching (2 /zg/animal/day;Gosner stage 26-28). These animals also exhibited preco-cious, graded elevations in whole-body triiodolhyroninc (T ),thyroxine (T4) and corticostcrone (B) when measured 24hours after injection of SV. Acute (2 h) dosc-rclatcd eleva-tions in whole-body hormone concentrations were induced byinjection of synthetic Xenopus CRH. Scaphiopus tadpolesaccelerate development in response to experimentally-inducedhabitat dessication, and this was accompanied by elevationsin whole-body concentrations of T , T4 and B. Treatment oftadpoles wilh CRH antagonist (oThclical CRF; 2 /jg/animal/day) or passive immunization with anli-CRH scrum blockedthe developmental response to habitat dessication. Handlingstress resulted in significant elevations of whole-body T4 at 2and 6 hours after the disturbance. These results providestrong support for the hypothesis that a CRH pcplidc plays acentral role as a transducer of environmental stress into anendocrine response during metamorphosis. (Supported byNSF grant IBN-92I9211).

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CHARACTERIZATION OF DISSOCIATEDCELLS FROM THE SYMBIONT-CONTAIN1NGCLAM GILLS OF Luciiia peclinata. C. S. Powell*and D. W. Kraus.Univ. of AL at Birmingham.

Specialized gill cells (bacteriocytes) of Liicinapeclinata which house dense populations of sulfide-oxidizing bacteria contain a high concentration ofhemoglobin, 1.5 mmole/kg. Spectrophotometricstudies of hemoglobin function in the thick fleshyintact gill are hampered by large diffusion distancesand high optical absorbances. The subfilamentarregion of the gill is comprised of numerous columnsof bacteriocytes. To facilitate hemoglobin studies,the columns were enzymatically dissociated fromthe chitin filaments supporting the overlyingciliated cells. The columns approximate the shapeof a hollow right cylinder with average length 400Hm, outer diameter 90 urn, and inner diameter 30pjii. Individual bacteriocytes, which average 20 nmin diameter, span the wall and are in direct contactwith the bathing solutions. Suspensions ofbacteriocyte columns are stable for at least 24 hoursand can be studied in our well-stirredspectrophotometer cuvette with negligible lysis.Bacteriocyte hemoglobin exhibits reactions withoxygen which approximate those of the purifiedprotein. Oxygen consumption rates of thebacteriocyte preparation are similar to those of theintact gill. Thus the bacteriocyte columns from thegills o f t . peclinata may represent an ideal modelfor investigations of the functional roles of host andsymbiont heme proteins in an intact symbiosis.Supported in part by NSF IBN9343430.

ENDOSYMBIOTIC ALGALCHLOROPLASTS SYNTHESIZE PROTEINSWITHIN THE MARINE ASCOGLOSSANSLUG, ELYSIA CHLOROTICA.R.W. Biron*1, M.E. Rumpho-Kennedy2, andS.K. Pierce1. 'Univ. of Maryland, College Parkand ^exas A&M Univ., College Station.

At metamorphosis, Elysia chlorotica forms anintracellular symbiosis with chloroplasts fromthe marine alga Vaucheria. "S-methioninebecomes incorporated into several chloroplastproteins in in vivo labeling experiments,demonstrating that chloroplast protein synthesisoccurs within the slug. Two of these proteinsare the peptides Dl (a photosystem II thylakoidmembrane protein) and the large subunit of themultimeric enzyme ribulose-l,5-bisphosphatecarboxylase/ oxygenase (Rubisco), which isrequired in carbon fixation. Chloramphenicolblocks the synthesis of these two proteins,demonstrating that they are translated within thechloroplast. This is the first evidence thatproteins required in photosynthesis arcsynthesized by the cndosynibiolic chloroplasts.In addition, the synthesis of several other,unidentified chloroplast proteins was inhibitedby cycloheximide, suggesting that these proteinsare translated in the cytosol and subsequentlytranslocated into the chloroplast. (Supported byNSF IBN-9117248)

553 554

MYCOSPORINE-LIKE AM1NO ACID (MAA)ENRICHED EMBRYOS OF THE GREEN SEAURCHIN SHOW REDUCED UV-INDUCEDCYTOKINETIC DELAY: EVIDENCE FORMAAS AS PHOTOPROTECTANTS.N.L. Adams*, A.K. Carroll, and J.M. Shick.Univ. of Maine, Orono.

Shallow dwelling and planktonic marineorganisms are exposed to solar ultraviolet (UV)radiation. Many such organisms contain UVabsorbing MAAs, for which a photoprotectiverole has been inferred from a positive correlationbetween MAA concentration and UV dose. Seaurchins can acquire MAAs from their diet ofMAA-rich algae. Female green sea urchins(Strongylocentrotus droebachiensis) maintainedon controlled algal diets provided either MAA-rich or MAA-deficient eggs, allowing directexamination of MAA function during UVexposure. UV-irradiated echinoderm eggstypically exhibit a delay in the first cell division.Eggs were tested for MAAs, and then batcheswere split and either UV-irradiated (>290 nm) ornot irradiated and held in the dark. Eggs werefertilized in synchrony and developmental timedocumented. MAA-enriched embryos showed asignificantly shorter UV-induced cleavage delaythan did MAA-deficient embryos, supporting therole of MAAs as UV photoprotectants.[Supported by NSF IBN-9316426 and SigmaXL]

PRELIMINARY ELECTRON PARAMAGNETICRESONANCE STUDY OF PROTECTIONAGAINST UV-INDUCED OXIDATIVE STRESSBY MYCOSPORINE-LIKE AMINO ACIDS(MAAs) IN OVARIES OF SEA URCHINS.J. M. Shick*, G. R. Bucttncr, and W. C. Dunlap.Univ. of Maine, Orono, Univ. of Iowa, Iowa City,and Australian Insl. of Marine Science, Townsvillc.

Sea urchins (Strongylocentrotus droebachiensis)maintained on a diet of the red alga Mastocarpusstellalus, which is rich in the UV-absorbing MAAshinorine (>-max=334 nm), subsequently had levelsof shinorine in their ovaries 10—25 limes those fedonly the kelp, Laminaria saccharina, which lacksMAAs. Pieces of ovaries excised from both groupswere placed in the cavity of a Bruker ESP 300spectrometer and exposed to UV and visible radiationfrom a 150 W xenon arc lamp fitted with <3O5 nmcutoff and 1R filters. Because ascorbic acid serves asthe terminal small molecule anlioxidant, the ascorbateradical (Asc*") was measured as an endogenousindicator of oxidative stress. The concentration ofAsc'" during illumination of the ovaries of Laminaria-fed specimens was significantly greater than that inovaries of Mastocarpus-ici urchins, suggesting aprotective effect of the higher concentrations ofshinorine in the latter. Shinorine itself did not haveantioxidant activity (W. Dunlap and Y. Yamamoto,unpublished). MAAs may protect against oxidativedamage by intercepting UV wavelengths anddissipating their energy without forming activeintermediates. [Supported by NSF IBN-9316426.]

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EFFECTS OF WATER STRESS ON THEVENTILATORY PATTERNS OF THE TICKDERMACENTOR ANDERSONI (ACARI:IXODIDAE).L.J. Fielden and J.R.B. Lighton. Univ. ofUtah.

Ventilatory patterns of unfed adult female D.andersoni were examined with a flow-throughrespirometry system that measured CO2 emis-sion rates. Water stress was defined in termsof the hydrational status of the tick and theambient humidity of the air, both of which hada marked effect on metabolic rate and thecyclic pattern of gas exchange. Hydratedanimals exhibited slow discontinuous ventila-tion in both dry (0% R.H.) and humid (95%R.H.) air. In dehydrated ticks, exposure tohumid air resulted in an increase in metabolicrate and a marked increase in the frequency ofthe discontinuous ventilation cycle. We proposethat this increase in energy expenditure andchange in ventilatory pattern was in part elic-ited by the active uptake of water in animalsattempting to regain water balance.

CONTROL OF RESTING VENTILATION INGRASSHOPPERS.S.L. Gulinson* and J.F. Harrison. ArizonaState University, Tempe, AZ.

In this study we tested for feedback controlof resting ventilation by hemolymph acid-base status and tracheal gases ingrasshoppers. We injected NaCI, NaOH,HCI and NaHCO3 into the hemocoel ofRomalea guttata and found no consistenteffects of pH, PCO2 or HCO3' on ventilationrate (VR, breaths-min'^). Only injections ofNaHCO3 caused an increase in VR. Wethen tested for effects of tracheal gases onVR by perfusing the tracheal system of intactSchistocerca americana with various gases.We found positive correlations between VRand tracheal PcO2 and negative correlationsbetween VR and tracheal PO2- Injections ofNaHCO3 into the hemocoel appear toincrease VR by increasing tracheal PCO2-Perfusing the tracheal system with highoxygen or low carbon dioxide gases causeslocusts to temporarily cease abdominalpumping. Quiescent grasshoppers do notmaximize gas exchange but instead closelyregulate tracheal PCO2 and PO2- Thisresearch was funded by NSF IBN 9317784.

557 558

EFFECTS OF HEAT AND CO, ONVENTILATORY FREQUENCY ANDUNIDIRECTIONAL PUMPING IN MELANOPLUSDIFFERENTIALS.D. Henderson* and H. Prangc. Indiana University,Bloomington.

Dolh heat and CO, stimulate increased vcmilatoryfrequency in insects. To investigate the differencesbetween these stimuli on vcntilalory patterns, eightgrasshoppers Melanoplus differcntialis were scaledbetween the inspiralory and expiratory spiracles inseparated sealed chambers in which pressure changescould be measured. Normal breathing patternsresulted in a decrease in pressure on the thoracic sideand an increase in pressure on the abdominal side ofthe chamber (i.e. flow from front to rear). In twoseparate experiments, temperature or CO2 was variedas a ventilatory stimulus. Both increased temperatureand CO, significantly increased venlilatory frequency(breaths/min ± S.E.): 27±3 at 30°C, 31±4 at 35°C,36+2 at 40°C, 44±4 at 45°C and 26±2 at 0% CO,,30+2 at 2% CO,, 36:5:3 at 4% CO2, at 6% CO,, 54±6at 8% COj. Unidirectional pumping as reflected bythe maximum pressure difference generated betweenthe front and the back showed a significantlyincreasing linear trend in the heated grasshoppers from293±59 Pa at 30°C to 578±44 Pa at 45°C. No suchchange in pressure difference was seen in llic CO,exposed grasshoppers. Heat and CO, exposuresdiffered in that CO, exposure did not increaseunidirectional pumping. This suggests that the stimulihave different cffccti and frequency alone ma) fail lagive an accurate picture of ventilation in grasshoppers.

FEEDBACK-INDEPENDENT ELEVATIONOF POST-EXERCISE VENTILATION RATEIN GRASSHOPPERS.K.A. Krolikowski* and J.F. Harrison.Arizona State University, Tempe.

Ventilation rate (VR, breaths min-1) risesafter hopping in locusts, in correlation witha fall in hemolymph pH and a rise inhemolymph PcO2- We tested whetherchanges in hemolymph acid-base status ortracheal gases were causally related to therise in post-exercise VR in Mclnnoplusdifferentinlis. Our data clearly show thatpost-exercise VR is not driven by feedbackregulation by hemolymph (pH, PcO2/HCO3-) or tracheal (Pco2/ P02) factors. Post-exercise VR was positively correlated withtrachea] O2 levels, and hoppingperformance increased at higher ir.ichenlO2, consistent with a feed-forwardmechanism of ventilatory control. PcO2'sin leg tracheal and hemolymph samplesexceeded PcO2's from thoracic trachealsamples, consistent with unidirectionalthorax-to-abdomen convective flow andnon-equilibrium conditions. This researchwas funded by N'SF IBM 9317784.

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MORPHOLOGICAL ASYMMETRY AND NUTRIENTASSIMILATION IN THE SOMATOCOELS OF ASTEROIDAND HOLOTHUROID LARVAE. W.B. Jaeckle,Smithsonian Marine Station, Ft. Pierce, FL

The somatocoels of planktotrophlc echinoderm larvaelie within the blastocoel and are spatially separated fromthe endo- and ectoderm. In examined asteroid andholothuroid larvae, a morphological asymmetry existsbetween the splanchnic and somatic sides of the leftsomatocoel. The splanchnic side is composed ofsquamous epithelial cells and the somatic side is com-posed of low-cuboidal cells. This asymmetry is lesspronounced in the right somatocoel during early larvalstages. Movement of macromolecules from the blasto-coel into the coelomic epithelia is supported by thepresence of basal coated pits and vesicles which occurchiefly in the squamous cells. In holothuroids, somaticsomatocoel cells possess a brush border and manyapical endocytotic pits and vesicles; the cells of thesplanchnic side lack these features. One explanation forthese differences is that the splanchnic side of thesomatocoels principally takes up nutrients from theblastocoel. The somatic side may also assimilatenutrients from the coelomic fluid. Larvae of Luidiaclathrata fed "C-labelled algal cells accumulated thelabel In the stomach and intestine after 225 min ofexposure; no label was detected in the somatocoels.However, after a 19+ h "chase" with unlabelled cells,the label was present in the somatocoelic epithelium.These results indicate that nutrients are translocated viathe blastocoel from the endoderm to the somatocoelsand support the hypothesis that these two epithelia arenutritionally integrated.

TRANSPORT OF NUTRIENTS FROM ADULTTO BROODED YOUNG IN SYNAPTULAHYDRIFORMIS (Echinodermata).JE Frick. Clemson Univ., SC.

S. hvdrifonnis broods itsyoung in the large coelom, wherethey develop immersed in adultcoelomic fluid. Yolk reserveswithin the egg are insufficientto account for weight gain ofjuveniles; high mortality ofyoung occurs upon removal fromthe adult. Adults, then, provideboth nutrients and protection.Analyses of brooding and nonbro-oding adult coelomic fluid indi-cate that juveniles decreasecarbohydrate, lipid, protein, andamino acid concentration. 14C-lipid, flourescent proteins, and50nm beads injected into theadult coelom are ingested andmetabolized by the brooded young.In using 14C-isotopes to studytransport, the relative roles ofthe coelomic and hemal systems ofholothurians have also beenstudied. Supported by NSF GrantsBSR-90-06599 to EE Ruppert, IBN-91-18702 to JP Wourms; Slocum-Lunz Grant to JE Frick.

561 562VELAR UPTAKE OF ALBUMEN IN THEGASTROPOD GENUS LITTORINA AND ITSSIGNIFICANCE FOR THE EVOLUTION OFLARVAL FORM.A.L. Moran. Univ. Oregon, Eugene

In many marine invertebrate taxa, lecithotrophic larvaehave reduced feeding or swimming characters whencompared to pianktotrophic relatives. The genusLittorina contains species with pianktotrophic andlecilhotrophic larvae, the latter of which feed onalbuminous material in benlhic capsules. Larvae ofboth types have well developed velar lobes, butlccithotrophs have reduced ciliation suggesting loss offeeding function. When I exposed three lecithotrophicUllorina species to labelled albumen, larvae showeduptake in both gut and velum. Four pianktotrophicUllorina species showed no velar uptake, suggesting thatthe albumen-absorbing role of the velum is newlyevolved. Lecithotrophic Littorina species may retain alarge velum as an absorptive device. Thus, larvalnutritional mode may affect the evolution of larval form.

Supported by NSF grant IBN-93-96004 to R. Emlet

DO ECHINOID LARVAE EXPRESSPHYSIOLOGICAL PLASTICITY INRESPONSE TO NUTRITIONALCONDITIONS? S.K. McWeeney.

Univ. of Florida, Gainesville.Il is not known if marine invertebrate larvae have

adaptations to maximize the rate of energyacquisition when food is abundant When foodconcentrations are high, they are not limited byparticle concentrations but by digestive processingcapabilities. If digestion rate could be increased inresponse to abundant food, this would allow larvaeto maximize energy acquisition and growth, andtherefore shorten the period of lime spent in theplankton. Digestive enzyme activity was examinedin larvae at the six aim stage, to determine if therewas a significant change in enzymatic rate due to achange in algal particle concentration. Larvae of thesand dollar Dendrasier excenlricus were culturedunder both high (5000 cells/ml) and low (1000cells/ml) food levels. It was hypothesized that iflarvae exhibit physiological plasticity, the enzymaticrate would change dramatically, as an adjustment bythe larvae in response to availability of food.Preliminary results, however, indicate that larvaeunder lower food concentrations express andmaintain much higher digestive enzyme levels thanlarvae under higher food concentrations.Supported by grants from Sigma Xi and Lcrncr-Gray (AMNH), and by NSF OCE-9115549 to Dr.Larry McEdward.

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563 564MATERNAL INVESTMENT VS LARVALFEEDING: EFFECTS ON DEVELOPMENTAND METAMORPHOSIS IN LARVAE OFTHE SAND DOLLAR ENCOPE ABERRANS.J.C. Herrera. Univ. of Florida, Gainesville.

The larva of Encope aberrans develops to afully-formed 8-arm echinopluteus on maternalinvestment alone, but does require externalnutrition to build the juvenile rudiment Maternalinvestment was reduced by isolating blastoraeresof 2-cell embryos. Full-size controls and 1/2-sizeembryos were fed Dunaliella tertiolecta (8CC11S/[UTI)or starved. Larvae from 1/2-sizc embryos requiredonly 12 hours more than full-size controls todevelop to the 8-arm plutcus. The ability of larvaefrom 1/2-size embryos to develop to the 8-armlarval stage without feeding challenges current lifehistory theory. In fed treatments larvae from 1/2-size embryos required 24 hours more than did full-size controls to reach metamorphosis. Whenmetamorphosis was induced simultaneously inboth fed treatments, juveniles from the full-sizecontrols were larger than those from 1/2-sizeembryos. When metamorphosis was induced atfirst evidence of competency in each treatment,there were no differences in juvenile size. Previousstudies indicating that juveniles from full-sizecontrols are larger may be misleading. This workshows that timing of induction of metamorphosisis critical. Supported by giants from Sigma Xi andLerncr-Gray (AMNH), and by NSF OCE-9115549 to Dr. Larry McEdward.

DOES FEEDING OR STARVATIONPROMOTE FISSION IN THE SEAA N E M O N E ANTHOPLEURAELEGANTISSIMA?J.S.Pearse*, V.B.Pearse, D.L.Secord, and C.E.Mills. Univ. of California, Santa Cruz, and Univ.Wash.

In a 15-month laboratory experiment atSanta Cruz, California, we tested whetherfeeding, starvation, or change in feeding regimepromotes fission in a clonal sea anemone. The72 ramets from 11 clones, collected locally andat Friday Harbor and Tatoosh Island,Washington, fissioned mostly in late spring-summer, with little difference among collectingsites, but much variation within and amongclones. Fission occurred mainly in ramets thatwere fed, either continuously or after 7 monthsof starvation. Little fission occurred withstarvation, even in large ramets fed for 7months before being starved. These experimentsindicate that fission is not promoted bystarvation as proposed previously; rather, itrequires food-as might be expected for anessential process in modular growth.

565 566A D U L T N U T R I T I O N A F F E C T SREPRODUCTION AND OFFSPRINGDEVELOPMENT IN AN ESTUARINENUDIBRANCH.CM. Chester (intro. by L.G. Harris). Dept. ofZoology, Univ. of NH, Durham, NH.

The effect of nutrition on reproductiveoutput and offspring development wasinvestigated in the estuarine nudibranch,Tenellia adspersa. Nudibranches fed an ad lib.diet of the hydroid Cordylophora werecompared to individuals that were starved for afour day period. Adult size, reproductiveoutput, size and weight of eggs, developmenttime and development mode were measureddaily. Adult size and reproductive outputdecreased rapidly with starvation. Starved adultsproduced smaller eggs; these eggs had a shorterembryological period and spend more time inthe plankton. All eggs produced by starvedadults had pelagic lecithotrophic developmentwhereas 20-50% of the eggs produced by fedadults underwent capsular metamorphosis. Thedevelopmental strategy utilized is influenced bythe nutritional condition of the adultnudibranch. The plastic life history of Tenelliafacilitates survival within the estuarineenvironment.

DIFFERENTIAL GROWTH AND NUTRIENTALLOCATION IN THE ECIIINOID LYTECIIINUSVAIUEGATUS FED NATURAL DIETS.S.D. Bcddingficld* and J.D. McClintock.University of Alntmmn nl Hirmingluim.

Lyicchinus uaricgatus occurs in abundance inthree distinct microhabitats in Saint Joseph's Bay,Florida. Field studies indicate at least five major foodsources arc utilized by this cchinoid, including thescagmsscs Thalaseia Ustudinum and Syringodiumfitiforme, cpibionts growing on the scagrasses, thegreen algae Enleronwrpha compressa, and dctritnlmaterial composed mainly of dead and decayingscagrass blades. The effects of these five differentfood items on growth and nutrient allocation wereinvestigated in the laboratory by presenting cchinoidsad libidum diets of each food type. Each food itemwas frccze-dricd and ground to a powder and thenimpregnated into agar food blocks of similar 6hapc.Individuals (n=24/treatmcnt) were offered cither amonospcciDc diet of one of the food items or a dietconsisting of a mixture of all five food items. Seaurchins fed a mixed diet and those fed cpibionts hadsignificantly (P<0.05) higher survival rates andsignificantly more of these individuals had maturegametes at the end of a six month period whencompared to the other four diet regimes. Growth(test diameter) was greatest in individuals fed S.fUiformt, T. testudinum and mixed diets, respectively.(Supported by NSF EHR-9108761 to J.B.McClintock).


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567 568BIOCHEMICAL INVESTIGATION OF THE VISUALPIGMENT IN ECHINODERMS.S. Johnscn. University of North Carolina, Chapel Hill.

Previous morphological and behavioral work on thecchinoderm dermal photoreceptor system has often beenlimited by a lack of concurrent biochemical data. Althoughhistochemical methods have localized proteins bound toretinal chromophorcs in asteroid optic cushions, the nature ofthe visual pigment in general and its distribution in thedermal photic system of cchinodcrms remains unknown. Thepresent study examined the nature of the visual pigment inAsterias forbesii by performing SDS-PAGE, Concanavalin-Aaffinity chromatography, and Western Blot Analysis onhomogenized arms. Using these techniques, a 35 kD proteinwas found that had the following properties in common withknown vertebrate and invertebrate rhodopsins: 1) molecularweight, 2) membrane localization, 3) mannose glycosylation.4) dimcrization and further aggregation in the presence ofsodium-tlodccyl-sulfate, and S) strong binding to twoseparate polyclonal antibodies to bovine rhodopsin. Theseresults strongly suggest that the 35 kD protein is a rhodopsinand is therefore also an cchinoderm visual pigment. Therelation of the echinoderm visual pigment to other rhodopsinssuggests at least two directions for further investigation of itsproperties: 1) examining its reactivity to various monoclonalantibodies to rhodopsin, and 2) amplifying and sequencing itscDNA. The first direction will characterize the tertiarystructure of the protein. The second will facilitate preciseand unambiguous localization of the visual pigment in thebody of cchinoderms. This localization will provide insightinto the structure and capabilities of the echinoderm dermalphotorcceptor system in particular and into the designprinciples of diffuse sensory systems in general.

QUANTITATIVE ANALYSIS OF SEA UR-CHIN SPERM SWIMMING.C.C. Gee* and R. K. Zimmer-Faust. Univ. ofSouth Carolina, Columbia.

Historically, those conducting studies ofsperm swimming patterns have examinedsperm contained within a droplet of water ona microscope slide. The presence of a solidboundary and the possible effects of surfacetension in such a situation cause concernsabout whether such studies accurately de-scribe the way sperm swim in open water.Considering this dilemma, we video tapedArbacia punctulata sperm as they swamwithin a large volume Plexiglas® chamberand then used a motion analysis system tocollect quantitative information about how thesperm swam. As we video taped the sperm,we ran concurrent fertilization assays to as-sess fertilization success and fertilizationrates during our experiments. Our resultsbear on studies of sperm chemotaxis as wellas on attempts to model fertilization success.This research was supported by grants fromthe Slocum-Lunz Foundation of South Caro-lina and NSF (OCE 94-16749).

569 570

MORPHOLOGICAL DICHOTOMY OFBRITTLE STAR ARM OSSICLES(ECHINODERMATA, OPHIUROIDEA):TAXONOMIC AND PHYLOGENETICIMPLICATIONS.E. E. LeClair, Committee on EvolutionaryBiology, University of Chicago, Chicago, IL

The brittle star arm contains a series ofarticulating vertebral ossicles that formflexible joints, allowing the arm to bend.A quantitative analysis of vertebral variationin 8 ophiuroid families (36 spp.) shows thatarm ossicles fall into two distinct groups:1) keeled, and 2) non-keeled vertebralforms. Each form shows within-group, size-related variation; no clear intermediates existbetween groups. In some species, however,an intermediate form occurs in the mostproximal series of ossicles within the disk. Asingle "transitional" ossicle, combiningfeatures of both types, stands between non-keeled and keeled ossicles within the arm ofa single individual. Anatomical evidencethus suggests that keeled vertebral ossiclesare derived from non-keeled forms; currentphylogenetic hypotheses for the groupfurther imply that the keeled vertebral formmay have developed more than once in theevolutionary history of the Ophiuroidea.

THE ST. AUGUSTINE "SEA MONSTER"AND THE BERMUDA "BLOB": Octopusgiganteus OR NOT?S. K. Pierce1', G. N. Smith, Jr.2, T. K.Maugel1 and E. Clark1. Univ. ofMaryland1, College Park and IndianaUniversity Medical School2, Indianapolis.

Two similar carcasses washed ontobeaches in Florida (1896) and Bermuda(1988). The former weighed tons and wasoriginally hailed as a gigantic octopus [0.giganteus (Verrill)]. Although Verrilllater disavowed his species description, ithas persisted for almost a century. Exceptfor a much smaller mass, the Bermudacarcass was very similar in gross mor-phology to the older specimen and sug-gested by some to be the same species. Wehave done biochemical and electron micro-scopic analyses on pieces of both remains.Both carcasses are huge masses of purecollagen fibers, no other cellular structureremains. The fiber arrangement indicatesthat both are likely from vertebrate skin.The amino acid composition indicates thatthe carcasses are the remains of differentspecies. The "Blob" is likely from a poikilo-therm, while the "sea monster" is likelyfrom a homiotherm. Neither is from anoctopus, supporting Verrill's disclaimer.

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571 572MUSCLE DEVELOPMENT IN SQUID:MORPHOLOGICAL CONSTRAINTS ONBEHAVIORW. M. Kier. Univ. of N. Carolina at Chapel Hill

The ultrastructural differentiation of themusculature of the arms and tentacles of juvenilesquid (Sepioteuthis lessoniana) was correlated withdevelopment of prey capture behavior recorded byhigh-speed video. The transverse muscle of thearms and tentacles was examined in a range fromhatchlings to five week old juveniles. Particularattention was paid to the differentiation of themyofilamcnt array in the transverse muscle fibersof the tentacles. These fibers are short sarcomerecross-striated cells, and thus differ from theobliquely striated cells of the transverse muscle ofthe arms and most other cephalopod muscle. Thefunctional significance of cross-striation and shortsarcomeres is a high shortening speed and it isthese cells that are responsible for the extremelyrapid (15-30 msec) tentacle strike. This study hasrevealed that cross-striations of the tentacle muscledo not begin to appear until approximately 3weeks. These results imply that the transversemuscle of the tentacle cannot shorten at as high avelocity in the newly hatched animals as in theadult. Indeed, the high-speed video recordingsshow a different mode of prey capture in theyounger stages that does not involve a tentaclestrike. The pattern of differentiation also providesinsight into the evolutionary origin of the muscle.Supported by NSF grant IBN 9219495.

CEPHALOPOD SUCKER DESIGN AND THEPHYSICAL LIMITS TO NEGATIVE PRESSURE.A.M. Smith. Butler Univ., Indianapolis, IN.

The maximum pressure differentials producedby different types of cephalopod suckers weremeasured with a pressure transducer, or calculatedfrom the force and area of attachment. Fourteenspecies from three orders were studied. At sealevel, cavitation, the cohesive failure of water,limits all cephalopod suckers to pressure differ-entials between 100 and 200 kPa (1 and 2 atm),regardless of their morphology.' As depthincreases, it becomes more difficult to cavitatewater. This allows suckers to produce greaterpressure differentials. The effect of depth oncavitation was simulated by performing themeasurements on a highly wettable surface. Whencavitation is no longer limiting, the morphologyand mechanics of the sucker determine themaximum pressure differential. Under these con-ditions, comparable to depths greater than 50m,stalked decapod suckers form stronger attachmentsthan unstalked octopod suckers. Octopod suckerscan produce pressure differentials up to 300 kPa,while decapod suckers can produce pressure differ-entials up to 800 kPa. Also, small suckers arecapable of greater pressure differentials than largesuckers.

573 574ADHESION FORCE OF ANTS ON SMOOTHSURFACESE.L. Brainerd. Univ. of Massachusetts Amherst.

Carpenter ants have an adhesive organ (arolium)on each foot and thus are able to stick to extremelysmooth surfaces. The arolium inflates with hemolymphas the ant places its foot against a surface, and thendeflates to detach the foot. Material that looks like aviscous liquid covers the arolium and is sometimes leftbehind as a footprint. Adhesion forces were measuredby three techniques: an oscillating beam was used toshake ants off surfaces, a centrifuge was used to spin antsoff surfaces, and the adhesion force of a single foot wasmeasured with a force transducer. Forces from all threemethods were in the range of 1 to 10 mN, or about tento fifty times the body weight of the ants. Force wasdependent upon surface wettability and detachment rate,thus suggesting that either a liquid or a viscoelaticmaterial may be responsible for adhesion.

PASSIVE F L I G H T STABILIZINGMECHANISMS IN BEETLES RELATED TOMORPHOLOGY.D.E. Alexander* and M.M. DeSouza. Univ. ofKansas, Lawrence.

Most beetles extend their elytra (wingcovers) laterally in flight, providing passivestability. A few beetle groups (e.g., scarabsubfamily Cetoniinae) fly with the elytra in thesame position as at res (flexed). We comparedthe stability of cetoniine beetles with that oftiger beetles {Cicindelidae) and June beetles(Melolonthinae), by towing them in a flow tank,using Reynolds number to maintain dynamicsimilarity. We towed the tiger and June beetleswith both flexed and extended elytra to comparethem with cetoniines with flexed elytra. Usingmaximum roll angle and lateral oscillation rateas measures of stability, we found that the tigerand June beetles were always much more stablewith extended than flexed elytra. Thecetoniines displayed unstable maximum rollangles (similar to other beetles with flexedelytra), but stable oscillation rates (similar toothers with extended elytra). Thus, themorphology of cetoniines seems to provide alimited stabilizing effect.


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575EITECTS ()|- TEMPERATURE IXIKINCMOLTING TO Tllli MECHANICALPROPERTIES OF MANDUCA SEXTALARVAL CUTICLES.J.S-Y Hsieh* and D.E. Alexander. Univ. ofKansas, Lawrence.

Tensile stress-strain measurements havebeen used to determine the material propertiesof the cuticles from caterpillars that wereexposed to three temperature conditions: 15degrees C, 25 degrees C and 35 degrees Cduring their molting period between the 4th and5th instars. The temperature at which thecaterpillars molted was found to modify theelasticity and the moduli of the cuticles. Thecuticles obtained from caterpillars in differenttemperature treatments were also found toexhibit different rates of viscoelastic creepunder constant loading analysis. Electronmicroscope studies have been initiated toinvestigate patterns of material failure anddetails of fracture behavior.

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576 577

THE VAGAL CARDIAC NERVES OFSKATES (RAJA ERINACEA AND R.EGLANTERIA).D.G. Sperry and R.L. Boord*.Univ. of Delaware, Newark.

Dissection of the rostralvisceral portion of the vagusnerve in Sudan black B stainedspecimens reveals the followingabout the nerve supply to theheart. A nerve that arises fromthe vagus in common with the i*-.l\branchial nerve gives rise tobranches that distribute toconnective tissue and rostralesophageal muscle and continuesalong the wall of the cardinalsinus, presumably enroute to thesinus venosus. Motoneurons whoseaxons are in this nerve arelocated in both the dorsal andventral motor nucleus of thevagus, but which are cardiac isunclear. No other nerves from thevagus course toward the heart butthe cardiac nerve is joined bybranches directly from the vagusor from a branch of the vaguscaudal to the accessory nerve(s).These anastomoses may includecardiac fibers. No branches ofvagus are exclusively cardiac.

H1STOCHEMISTRY OF VENTRAL SKINGLANDS IN THE ARBOREALSALAMANDER, ANEIDES LUGUBRIS.N.L. Staub* and J. Paladin. GonzagaUniversity, Spokane, Washington.

In 1929 Noble made the interestingobservation that female Aneides lugubrispossess caudal hedonic glands, glandswhich are typically found only in maturemales. Our recent histochemicalanalysis of ventral caudal skin confirmsthis observation. We identified threetypes of glands in male and female Aluaubris. including mucous glands,granular glands, and glands which aresimilar to caudal hedonic glands.Mucous glands stained positively inalcian blue. Granular glands wereslightly PAS positive and the presumptivecaudal hedonic glands were stronglyPAS positive. Morphologicalcharacteristics also distinguish the glandtypes. These findings suggest thatcaudal hedonic glands are not alwayssexually dimorphic and highlight theunique derived morphology of Aneideslugubris. Supported by NSF grant IBN-9306523 and by the Murdock CollegeScience Research Program.

578 579

SEXUAL DIMORPHISM AT THE CYTOLOC1CALLEVEL: HISTOLOGY AND HISTOCHEM1STRY OFFORELIMB MUSCLES IN THE LEOPARD FROG, Ranapipiens.D.G. Blackburn. Trinity College, Hartford, CT.

Analysis of the forelimb musculature of leopardfrogs indicates that several of the muscles areconsiderably larger in mass and protein content inmales than in females. To determine contributionsof hypertrophy and hyperplasia to this sexualdimorphism, histological sections were analyzedquantitatively with the aid of a digitizing tablet.In some dimorphic muscles (e.g., coracoradialisand the superior head of the extensor carpiradialis), males exhibited significantly more fibersthan did females. Various other muscles showedno evidence of male hyperplasia. Among these isthe flexor carpi radialis muscle, in whichintersexual differences in muscle mass areattributable to the unusually small size of themuscle fibers in females. Histochemical analysisof the coracoradialis muscle revealed a higherproportion slow oxidative fibers and a lowerpercentage of fast glycolytic fibers in males thanin females. Previous studies suggest that thismuscle undergoes prolonged contraction in malesduring mating (amplexus); thus, the differences infiber composition may be functionally significant.

MORPHOLOGICAL CRITERIA USED INF O R M U L A T I N G P H Y L O G E N E T I CHYPOTHESES OF SPERM STORAGE INFEMALE SALAMANDERS (AMPHIBIA:CAUDATA).David M. Sever. Saint Mary's College, NotreDame, Indiana.

Possession of cloacae is the ancestral state forvertebrates, but presence of cloacal spermstorage glands, spennathecae, is unique to theseven families of salamanders comprising thesuborder Salamandroidea. Morphological dataarc discussed relevant to three hypotheses. (1)The plesiomorphic condition for duration ofsperm storage in spennathecae is two weeks orless. (2) The ancestral function of spermathecalsecretions is to flush sperm from thespennathecae during oviposition to ensureinternal fertilization as eggs pass through thecloaca. (3) The occurrence of spennathecae isnot a synapomorphy for the Salamandroidea butis polyphyletic within the suborder.


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580 581EVOLUTION OF THE BALANCER ORGAN INLARVAL URODELES.A.J. Crawford. Univ. of Chicago.

The balancer organ is a transi-tory larval feature found only incertain urodele species. It gen-erally occurs in species possess-ing a pond-type mode of life-history. The present study at-temps to explain the exceptions tothis pattern by using phylogenet-ics and comparative morphology.Data on the taxonomic distributionof the balancer organ was compiledfrom the literature, integratedwith current phylogenetic hypothe-ses, and the natural history ofeach species was compared to thatexpected of a pond-type urodele.The results suggest the balancerorgan evolved independently 2 or 2times at the family level, withsubsequent losses. The pattern oidistribution displays at all tax-onomic levels a historical as wel]a functional component. No morph-ological differences have yet beetfound. It is suggested that theevolutionary origin of the balancer may be an indirect consequenceof selection for large clutchsize.

RELATIONSHIPS AND MORPHOLOGICALDIVERGENCE OF THE AN0L1NE GENERAANOLIS, CH AMAELINOROPS, ANDPHENACOSAURUS.JACKMAN. T.R.*,K. de QUEIROZ, J.B. LOSOS, andA. LARSON. Washington Univ., St. Louis, and theNational Museum of Natural History, Washington D.C.

The monotypic Hisaniolan lizard genusChamaelinorops possesses a suite of uniquemorphological characteristics associated with crypticbehavior in leaf litter. Phenacosaurus is a SouthAmerican genus of twig anoles that exhibitsseveral morphological characters different from Anolis.Based on morphological divergence, both genera havebeen thought to be early offshoots of the anolineradiation. A phylogenetic analysis of combinedmitochondrial and nuclear DNA sequence data showsthat the Anoline genera Chamaelinorops andPhenacosaurus are within the genus Anolis. The DNAsequence data is congruent with the morphological datain the group. There is no evidence for retained primitiveosteological features in Chamaelinorops orPhenacosaurus that would render Anolis monophyletic.

ABSTRACTS 131A

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