Meeting Abstract

38.4  Friday, Jan. 4  PERIRECEPTOR ROLE FOR THE HARDERIAN GLAND IN PHEROMONE DETECTION IN GARTER SNAKES MASON, R.T.*; HALPERN, M.; Oregon State University; SUNY Health Science Center at Brooklyn masonr@science.oregonstate.edu

One of the few vertebrate pheromones that has been isolated, purified, and characterized is the sex pheromone of the red-sided garter snake (Thamnophis sirtalis parietalis). When males encounter a female expressing the pheromone, they exhibit stereotyped courtship behaviors including chin rubbing, rapid tongue-flicks, and caudocephalic body undulations. The pheromone, a nonpolar, hydrophobic blend of 13 long-chain (C₂₉�C₃₇) saturated and monounsaturated methyl ketones, is insoluble in aqueous solutions. This pheromone is detected by the vomeronasal organ (VNO), which is specialized for the reception of nonvolatile chemical cues. Male garter snakes deprived of a functional vomeronasal (VN) system are unable to detect or respond appropriately to this pheromone. But the mechanism by which the hydrophobic pheromone gains access to the aqueous environment of the VNO is unknown. Results to date indicate that the Harderian glands� (HG) secretions, which duct exclusively into the VNO in snakes, contain pheromone-binding proteins. For over 300 years, the function of the cephalic HG of vertebrates has been the subject of speculation from numerous sources. Certainly their relatively large size, their phylogenetic age, and persistent conservation in almost all tetrapod groups as they emerged from an aqueous to an air/land environment suggest that they probably play an important role in the physiological adaptation to terrestrial life. This presentation will examine the role of the HG as a mediator in providing access for the female sex pheromone to the VNO of male garter snakes. Since detection of the female sex pheromone is critical to initiate male courtship behavior, the effects of HG removal on courtship behavior and prey attack, both known to require a functional VN system, have been examined. Supported by NSF IOB 0620125.