| Past studies have shown that spermiating male sea lampreys ( Petromyzon marinus) release a bile acid sex pheromone 7α, 12α, 24-trihydroxy-5α-cholan-3-one-24 sulfate (3-keto petromyzonol sulfate) that under laboratory conditions, induces search and preference behaviors in ovulating females. However, the site of synthesis and excretion of 3-keto petromyzonol sulfate, the electrophysiological potency and specificity of 3-keto petromyzonol sulfate to the olfactory organs of females, and the effectiveness of 3-keto petromyzonol sulfate and water conditioned with spermiating males in a natural spawning environment have not been determined. In addition, whether bisazir-sterilization of males (a current sea lamprey management technique) affects sex pheromone function and thus competitiveness, has not been determined. In this dissertation, results from behavioral assays, electro-olfactograms, biochemical analyses, and immunucytochemistry showed that 3-keto petromyzonol sulfate is produced in the liver and released exclusively through the gills of spermiating male sea lampreys. Also, electro-olfactograms indicated that 3-keto petromyzonol sulfate is detected at a concentration of 10−12 M and discriminated from other conspecific bile acids by the olfactory organs of female sea lampreys. Furthermore, in-stream behavioral assays demonstrated that 10−12 M 3-keto petromyzonol sulfate and water conditioned with spermiating males (containing 2 × 10−12 M 3kPZS) function in a natural spawning stream by attracting ovulating females 65 m to the source of each stimulus. Finally, behavioral assays, electro-olfactograms, and mass spectrometry showed that bisazir-sterilized males released a potent odorant (3-keto petromyzonol sulfate) that attracted ovulating females. Combined, these results further elucidate the mechanisms whereby mature males attract mature females and confirm that spermiating males release a sex pheromone that functions over relatively long distances. Overall, these results have the potential to impact sea lamprey management by facilitating the pursuit of techniques that exploit sex pheromone communication in sea lampreys and better our understanding of sex pheromone communication in fish and vertebrates. |
