1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

17 Givaudan LectureFISHING FOR NOVEL GENESDowling J.E. 1 1 Molecular and Cellular Biology, Harvard University,Cambridge, MAZebrafish are highly visual animals, exhibiting robust light responsesafter just 4 days of development, making them ideal for the geneticanalysis of visual behaviors. They have large eyes and aretetrachromatic, possessing ultraviolet- sensitive cones as well as red-,green- and blue-sensitive cones. Our group has developed behavioraltests that can be used to uncover visual system specific mutations inzebrafish. One test, based on the optokinetic reflex, enables us toisolate recessive visual system mutations in 5-7 day-old larval fish thatappear normal morphologically. We have isolated totally blind,partially blind, color blind and movement-defective mutant fish. Asecond test, based on the escape response, permits us to isolatedominant mutations in adult fish that demonstrate late onset retinaldefects or degenerations. We also examine young mutagenized fish fordevelopmental eye defects. Eye development is rapid in zebrafish;within 24 hours postfertilization (pf), a well formed eye is present.Differentiation of the neural retina occurs between 1 and 3 days pf, sothat by 3 days the retina appears functional. In this presentation, I shalldescribed representative behavioral and developmental mutants out ofthe more than 150 we have so far isolated. Other non-visual behaviorscan also be elicited easily in zebrafish and hold promise for geneticanalysis. For example, zebrafish show robust place conditioning tococaine. After just one exposure, they repeatedly return to that part ofthe tank where the exposure first took place. So far, we have isolatedthree mutants that show altered sensitivity to cocaine. Behavioral testsfor memory and learning in zebrafish have been developed in ourlaboratory and will also be discussed.18 Slide Ecology and Social ChemicalsFUNCTION OF ODORS AND CHEMOSIGNALS IN BIRDSHagelin J. 1 1 Biology, Swarthmore College, Swarthmore, PABird responses to avian-derived odors challenge the traditional viewthat birds mediate social behavior primarily through sight and sound.Here I review several new and exciting discoveries regarding the waysin which odors affect bird behavior. The evidence indicates: (1) Odorproduction is widespread in birds. (2) Odors are linked to a variety ofsocial situations, all of which involve adaptive behavioral responses,such as (a) discrimination between the scent of mates and conspecifics,including aversion to self-odor, (b) courtship and sexual selection, (c)nest building and homing to the odor signature of an individual´sspecific nest site, and (d) odor learning in chicks. Combined, the datasuggest that an individual´s odor profile may convey informationrelevant to complex behavioral responses, such as kin recognition,inbreeding avoidance, the genetic compatibility of a mate, and parasitemediatedsexual selection. The chemical signals of birds represent anentirely new mode of avian communication that has the potential toreveal new and interesting aspects of vertebrate behavioral ecology andsensory perception. Every bird studied thus far has a functionalolfactory system, but we have yet to obtain a general understanding ofhow odors impact the day-to-day social behavior of any avian species.Future, interdisciplinary studies that explore avian odor chemistry,neuroanatomy and social behavior hold great promise, particularly thosethat compare avian scent to odor-based patterns that are welldocumentedin other vertebrate systems, such as mammals and fish.Funding provided by National Geographic Research and ExplorationGrant.19 Slide Ecology and Social ChemicalsOLFACTION, MECHANORECEPTION AND VISION AREUSED IN THE LOCATION OF A TURBULENT ODOR SOURCEBY A BENTHIC SHARKGardiner J.M. 1 , Atema J. 1 1 Biology, Boston University, Woods Hole,MASince turbulent dispersal causes many odor plumes to consist ofchemical and mechanical (momentum) discontinuities, aquatic animalsmay localize the source of these odor plumes by simultaneous chemoandmechanoreception: Eddy-chemotaxis. We wanted to examine theroles of olfaction, mechanoreception, and vision in food odorlocalization behaviors of a benthic shark, the smooth dogfish, Musteluscanis. Two turbulent plumes were created in a flume: a) squid rinse andb) seawater. The sources of odor and turbulence were physicallyseparated by placing a brick downstream from each oozing odor source.The small odor sources created minor turbulence; each brick caused amajor turbulent wake. Sides were alternated to account for side bias.Each shark (n=8) was allowed to acclimate and then confineddownstream while the plumes were established. After release itsbehavior was monitored for ten minutes. The number of strikes on eachobject was counted under two light conditions: fluorescent and infrared.Strikes on either target on the non-odor side were rare. On the odor side,all animals struck the source of turbulence significantly more than theactual source of odor. More strikes occurred in the light condition butpreference for the source of odorous turbulence did not change. Theseresults show that the smooth dogfish is using simultaneous informationfrom its olfactory and turbulence detection systems when searching forfood and that they may be using additional visual information.Preliminary experiments have shown that eliminating lateral line inputcauses serious disruption of localization behavior. Support: DARPA20 Slide Ecology and Social ChemicalsSEA HARE (APLYSIA CALIFORNICA) DEFENSIVESECRETIONS ALSO CONTAIN PYRIMIDINE AND OTHERALARM CUES THAT WARN CONSPECIFICS OF NEARBYPREDATORSKicklighter C. 1 , Germann M.W. 2 , Kamio M. 1 , Kubanek J. 3 , Derby C. 11 Biology, Georgia State University, Atlanta, GA; 2 Chemistry, GeorgiaState University, Atlanta, GA; 3 Biology, Georgia Institute ofTechnology, Atlanta, GAWhen attacked by predators, such as spiny lobsters and seaanemones, the sea hare Aplysia californica releases ink and opaline.These secretions chemically defend A. californica, facilitating its escapeupon attack. In addition to modifying predator behavior, ink and opalinealso affect conspecifics by functioning as alarm cues. When juvenile A.californica are presented with ink or opaline from other individuals,they exhibit alarm behaviors such as head withdrawal, moving awayfrom the stimulus, and escape locomotion. Thus, the release ofsecretions by a sea hare that has been attacked signals to nearbyconspecifics that a predator is nearby and evasive behaviors should beproduced. Utilizing bioassay-guided fractionation, we have trackeddown the active molecules in A. californica ink and opaline that elicitthese responses. We have determined that four compounds in ink, threeof which have been identified as the nucleosides uridine and cytidine,and the base uracil, separately elicit alarm behaviors in juvenileconspecifics. Two components in opaline also function as alarm cues.We are currently in the process of identifying these unknownmolecules. In addition, the alarm response by Aplysia californica is notspecies specific, as A. californica respond to ink from the octopusOctopus bimaculoides and the squid Loligunculus brevis. Analyses ofthese inks demonstrate that they contain uridine and uracil, suggestingthat these alarm cues are conserved among ink-producing mollusks.Supported by NSF IBN-0324435, 9876754, 0322773.5