John W. Chinn

Sex and seasonal differences in the skin lipids of garter snakes.

1. This study investigates the skin lipids of male and female red-sided garter snakes both in the breeding season and in the non-breeding season. 2. Skin lipids were analyzed by means of thin-layer chromatography (TLC) and gas chromatography/mass spectrometry (GC/MS). 3. Distinct differences exist in the skin lipids of males and females. 4. Samples obtained during the breeding season were qualitatively different from those acquired during the non-breeding season.

Synthesis of lithiomethanes (CH4−nLin) and characterization of the vapor species of lithiomethanes by flash vaporization mass spectroscopy

Abstract An extensive study of the reaction chemistry of halocarbons with high temperature lithium vapor is reported. New syntheses are reported for dilithiomethane and methyllithium, and an improved synthesis for tetralithiomethane has been developed. The new compound trilithiomethane has also been prepared.

Skin Lipids of Garter Snakes Serve as Semiochemicals

Chemical communication in the Reptilia has not been widely studied despite the fact that many species of lizards and snakes rely heavily on chemical cues obtained by tongue-flicking. As early as the 193Os, G. K. Noble’ hypothesized that integumental chemical cues play a powerful role in garter snake reproductive behavior. The red-sided garter snake, Thamnophis sirtalis parietalis, is the most northerly living reptile in North America and perhaps the world. In the spring, garter snakes leave underground hibernacula where they have hibernated the previous winter. In Manitoba, Canada where our studies are conducted, these animals hibernate together in large groups of up to several thousand animals? Upon emergence, male garter snakes congregate around the entrances to the dens waiting for females that emerge singly or in small groups. When a male encounters a newly emerged female he will investigate her, tongue-flicking repeatedly. All newly emerged females are sexually attractive and elicit courtship behavior from males. Soon, groups of males begin to court females when the males detect a pheromone on the female’s dorsal surface. Courtship ensues as the males press their chins onto the female’s back. “Chin-rubbing” is accompanied by rapid tongue-flicking by the male. This tongue-flicking behavior serves to deliver chemical cues from the female’s dorsal surface to the male’s vomeronasal organ.3 We have been investigating the chemical communication used by garter snakes in conjunction with their reproductive behavior. Previous work4 has demonstrated that chemical cues removed from the female’s integument with hexane elicit courtship behavior from male garter snakes. These results suggest that nonpolar lipids are serving as semiochemicals in these snakes. Our studies to date have focused on isolating and identifying the sex-recognition pheromone of the red-sided garter snake. We have used the techniques of thin-layer chromatography (TLC) and gas chromatography /mass spectrometry (GC/MS). During the breeding season, hexane washes of the skin of males and females show different components on charred TLC plates. These results suggest a sex difference in the skin lipids of males and females. Analysis of the same samples using GC/MS confirmed this hypothesis. FIGURE 1 shows a clear sex difference in the GC trace of males as compared to females. Mass spectral data identified primarily long-chain fatty acids in the male washes. The female washes were comprised mostly of small hydrocarbons as well as cholesterol and two other steroids similar in structure to androstanediones. Both males and females possess cholesterol in their skin lipids.