1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

289 Poster Central Olfaction and Chemical EcologyRELEASE, DETECTION, DISCRIMINATION, ANDASSOCIATIVE LEARNING OF CONSPECIFIC BILE ACIDS BYMIGRATORY RAINBOW TROUT (ONCORHYNCHUS MYKISSKAMLOOPS)Thwaits B.F. 1 , Fine J.M. 1 , Sorensen P.W. 1 1 Fisheries, Wildlife, andConservation Biology, University of Minnesota, St. Paul, MNAlthough it is well established that Pacific salmon (Oncorhynchusspp.) locate home streams for spawning using odorous cues they learnas juveniles, the identities of these cues are as yet unknown. It has beenspeculated that odors from both abiotic and biotic stream contents,incuding the odor of juvenile conspecifics (and perhaps other fishes)could be part of imprinted home stream odor. If so, bile acids, a class ofdistinctive steroids released by many fishes (and used as a migratorypheromone by the sea lamprey), could be part of the odor salmonrecognize. Here we tested this possibility using a migratory strain ofrainbow trout (Oncorhynchus mykiss). Chemical analysis revealed thattrout release a distinctive mixture of three bile acids: taurocholic acid,taurochenodeoxycholic acid, and cyprinol sulfate. EOG and multi-unitolfactory nerve recording showed that the trout peripheral olfactorysystem detects these and three other bile acids in dose-dependentmanners down to concentrations of 10 -11 M. Binary mixtureexperiments also showed that these bile acids activate different sets ofolfactory receptors. Finally, ongoing classical conditioning isdemonstrating that trout can learn to discern and remember individualbile acids for extended periods of time. In conclusion, bile acids appearto have all the characteristics required for them to be part of naturalhomestream odor. Supported by Minnesota Sea Grant.290 Poster Central Olfaction and Chemical EcologyPUTATIVE STEROIDAL PHEROMONES: SYNTHESIS SITESAND OLFACTORY EPITHELIAL RESPONSES IN THEROUND GOBY (NEOGOBIUS MELANOSTOMUS)Jasra S.K. 1 , Avci Z. 1 , Corkum L. 2 , Scott A.P. 3 , Li W. 4 , Zielinski B. 51 Biology, University of Windsor, Windsor, Ontario, Canada; 2 Universityof Windsor, Windsor, Ontario, Canada; 3 University of Windsor, Dorset,England, United Kingdom; 4 Fisheries and Wildlife, Michigan StateUniversity, East Lansing, MI; 5 Biological Sciences, University ofWindsor, Windsor, Ontario, CanadaPheromone communication may be important for the reproductivesuccess of the round goby (Neogobius melanostomus), an invasive fishspecies in the Great Lakes. The signaling molecules released byreproductive males to attract gravid females may include steroidalcompounds synthesized by the testes and accessory reproductive glands.Our previous studies have shown that the testes produce steroids thatare potent stimulants of olfactory sensory activity in female roundgobies. In this study, we investigate the role of accessory gonadalglands in the production of steroidal putative pheromones in male roundgobies. The base of each testis is attached to a seminal vesicle, and amesorchial region with a prominent fold is located between the twotestes. A separate glandular mass is at the base of the testes, adjacent tothe common sperm duct. The accessory reproductive glands withsteroidogenic cells were identified, by histological and histochemicalprocedures. Immunocytochemistry against 11 beta-hydroxysteroiddehydrogenase indicates an abundance of steroidogenic Leydig-likecells interstitial to the columnar epithelium in the mesorchial gland, andsparser immunoreactive cells in the seminal vesicles. Incubation of theseminal vesicles with steroidal metabolic precursors, yielded steroidsthat stimulated electro-olfactogram responses when presented atpicomolar concentrations. These results are indicative of a pheromoneproducing function for the accessory gonadal glands in male roundgobies. Supported by NSERC Discovery and Strategic Programs.291 Poster Central Olfaction and Chemical EcologyCRESTED AUKLET ODOR IS INDICATIVE OF A FEATHERORNAMENTChua W. 1 , Hagelin J. 1 , Preti G. 2 , Wysocki L. 2 1 Biology, SwarthmoreCollege, Swarthmore, PA; 2 Monell Chemical Senses Center,Philadelphia, PACrested auklets (Aethia cristatella) produce a citrusy, socialchemosignal that is linked to a seasonal display (the “ruff-sniff”). Totest whether scent exhibited patterns indicative of a secondary sexualornament, we examined seasonal changes in odor at two locations onthe body (the ruff, where displays are focused, and the rump). We madetwo predictions: (1) Odor of ruff feathers would be greatest early in thesummer breeding season, but drop by the end of the season. (2) The ruffwould be more scented than the rump early in the season. Three keyaldehydes of auklet scent (octanal, decanal, and cis-4-decenal) wereanalyzed via solid phase microextraction (SPME) and gaschromatography/mass spectrometry (GC/MS). All compounds weremore concentrated in the ruff at start of the season (June) than at the end(August; median odor loss: octanal = 32%, decanal = 54%; cis-4-decenal = 72%; 9 ≤ n ≤ 17; -2.53 ≤ Z ≤ -1.78; 0.006 ≤ P(one-tailed) ≤0.04). Rump feathers did not exhibit a striking odor-loss pattern (7 ≤ n ≤14; -1.38 ≤ Z ≤ 0.48; 0.09 ≤ P(one-tailed) ≤0 .45). Concentrations oftwo compounds (octanal and decanal) were greater in ruff feathers earlyin the season than the rump (6 ≤ n ≤ 10; 2.24 ≤ t ≤ 2.85; 13.3 ≤ df ≤14.0, 0.013 ≤ P(one-tailed) ≤ 0.022). Combined, our results areconsistent with odor acting as an olfactory ornament. Odor is greatestearly in the season, when ruff-sniff displays are emphasized. At thissame time, two of three odor compounds are also concentrated in theruff, which is the focus of displays. HHMI student stipend and NationalGeographic provided funds.292 Poster Central Olfaction and Chemical EcologyRESPONSE OF A TANGERINE-SCENTED SEABIRD TO ODORAND VISUAL CUESTigue C.C. 1 , Hagelin J.C. 1 , Wenzel B.M. 2 1 Biology, SwarthmoreCollege, Swarthmore, PA; 2 David Geffen School of Medicine, UCLA,Los Angeles, CACrested Auklets (Aethia cristatella) are arctic seabirds that use bothseasonally elevated scent and visual ornaments during socialcommunication. We explored the relative importance of odor and visualsignals in a non-social context. We trained captive birds to touch the tipof their beaks to a Y-shaped stick for a food reward, a behavioral taskknown as "targeting." The Y-stick gave birds a simultaneous choicebetween an experimental and control stimulus. Experimental stimuliincluded (1) synthetic Crested Auklet odor, (2) a visual (color) stimulusonly, and (3) auklet odor plus the visual stimulus. Birds learned toassociate food rewards with each type of experimental stimulus (odoronly: Z = 439.50, df = 44, P < 0.0001; visual only: Z = 105.00, df = 19,P = 0.0001; visual + odor: Z = 76.50, df = 16, P = 0.0001). However,the presence of a visual cue greatly enhanced targeting accuracy by47% to 56% over the odor stimulus alone (14.0 ≤ Z ≤ 16.0; df=7; 0.016≤ P ≤ 0.023). Our data indicate: (1) Crested Auklets are capable of odorlearning in non-social contexts, and (2) learning is facilitated withvisual stimuli. Such a pattern is consistent with field tests of aukletodor, which indicate an emphasis on visual ornaments. Odor appears toexhibit a synergistic relationship with visual displays. We are currentlyexamining whether variation in odor learning corresponds to anindividual´s social rank, and whether sensitivity to odor variesseasonally or by sex. Funding provided by Aquarium of the Pacific,Long Beach, CA and Swarthmore College field funds.73