No description available.

No description available.

Pacific herring, Clupea harengus pallasi, possesses a pheromone in the milt and testes that triggers spawning behaviour in reproductively mature individuals of both sexes, and plays a role in synchronizing the school spawning that is distinctive of this species. The pheromone was found to be effective as a transient olfactory stimulus in eliciting a behavioural response that varied in the degree of expression and time course. Stimulus strength was found to influence the time course of the response, whereas differences in maturity, evident through examination of plasma levels of steroids, were correlated with a propensity to respond to the pheromone. Input from factors other than the spawning pheromone appear to be needed to elicit prolonged spawning; some of these factors also act through olfaction. Immediate effects of stress were not found to influence the response to the spawning pheromone. Plasma levels of reproductive steroids of herring during the spawning season were measured with radioimmunoassays. Peak levels of 17,20β-dihydroxy-4-pregnen-3-one (17,20β-P) were found to coincide with final maturation in females and the initiation of milt production in males, suggesting that this steroid is the maturation-inducing steroid of this species. Other features found to be distinctive of the reproductive physiology of the herring included low plasma levels of the unconjugated maturation-inducing steroid, high levels of 17α-progesterone (17-P) and 3α,17α-dihydroxy-5β-pregnan-20-one (3α,17-P-5β), and high levels of glucuronated steroids. Structural investigation of the pheromone with liquid chromatography/ mass spectrometry showed that it consists of at least two components which do not elicit a behavioural response individually. One of these compounds is sulphated 17,20β-P. The structure of proteinaceous hormones involved in controlling reproduction of the herring was also investigated. It was shown that this species possesses three forms of gonadotropin-releasing hormone (GnRH) in the brain, one with a structure that has not been reported before. These results indicate that the presence of three GnRH forms is a primitive, rather than derived, condition in the teleosts. The structure of the (β-subunit of gonadotropin II (GtH ll-β) of herring was also deduced by isolation of a cDNA for this molecule. The structure of the herring GtH ll-β was found to be quite different from other teleost molecules of this kind, and a phylogenetic analysis of known GtH ll-β structures suggests that the β-subunit of both mammalian gonadotropins may be most closely related to the β-subunit of teleost GtH-l. / Graduate

Vita. / Digitized by Kansas Correctional Industries

Pheromones are chemical cues produced by organisms that affect the behavior and/or physiology of conspecifics. The orchestration of reproductive behaviors in many animals depends on the expression of sex pheromones. In insects, intraspecific variation in sex pheromone expression is commonly observed and often influences social interactions between individuals. To what extent similar variation is present in vertebrate sex pheromone systems is not well understood. This thesis investigated the occurrence and significance of phenotypic variation in the sexual attractiveness pheromone of the red-sided garter snake, Thamnophis sirtalis parietalis. Composed of a homologous series of saturated and unsaturated methyl ketones sequestered in the skin lipids of females, this pheromone elicits male courtship behaviors during the breeding season. Variation in the expression of the sexual attractiveness pheromone was examined at three levels: seasonal, individual and populational. Seasonal variation in pheromone expression was examined with respect to trailing behavior. In field experiments, males followed female trails during the breeding season but not during the non-breeding season. Skin lipid analysis revealed marked differences in pheromone composition between the two seasons, suggesting a role for this pheromone in regulating male trailing behavior. Individual variation in pheromone expression was examined with respect to mate choice. In arena trials, males displayed a courtship preference for larger females and continued to demonstrate this preference when visual, tactile, and behavioral cues from the females were removed through the use of skin lipid extracts. Analysis of pheromone profiles from individual females showed size-specific variation in composition, demonstrating that this pheromone can function as a reliable indicator of female size. Finally, populational variation in pheromone expression was examined with respect to sexual isolation among hibernacula. In arena and trailing experiments, males preferred to court and trail resident (same den) females over non-resident (distant den) females. Chemical analysis showed significant inter-den variation in pheromone composition, suggesting that this pheromone represents the cue that males use to identify females from their own population. In summary, these studies demonstrate that significant variation exists in the female sexual attractiveness pheromone of the red-sided garter snake and suggest that this variation has functional significance for this species. / Graduation date: 2002

Graduation date: 1994

Thesis (Ph. D.)--University of Oregon, 2003. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 93-100). Also available for download via the World Wide Web; free to University of Oregon users.

No description available.

No description available.

No description available.