Sulfated Bile Acids as Putative Sex Pheromone Components in Pacific Lamprey

Abstract

Pacific Lamprey Entosphenus tridentatus, which is native to the Pacific coast of North America, is an important fisheries resource for some Native American communities and so has been a conservation concern. Chemical analysis of water conditioned with mature male Pacific Lampreys and electrophysiological examination of the identified sulfated bile acids revealed that Pacific Lampreys may use the two bile acid compounds, 3-keto petromyzonol sulfate (3kPZS) and petromyzonol sulfate (PZS), as mating pheromones that can attract ovulatory females and stimulate them to nest. Liquid chromatography–mass spectrometry analysis on extracts of water conditioned with mature male Pacific Lampreys identified both 3kPZS, known as a major sex pheromone component, and PZS, known as a component of migratory pheromones in Sea Lamprey Petromyzon marinus. When combined with the previous electro-olfactogram (EOG) data demonstrating olfactory sensitivity of Pacific Lampreys to both compounds, the identification of the two bile acid compounds suggests that Pacific Lamprey evolved to have a chemical communication system for reproduction similar to that of Sea Lamprey. Further studies are required to confirm putative pheromonal functions of these two compounds in Pacific Lamprey. Comprehensive understanding of the reproductive behavior mediated by sex pheromones may provide a helpful tool in restoring the dwindling Pacific Lamprey populations along the North Pacific coast of North America.

Received March 7, 2014; accepted July 10, 2014

ACKNOWLEDGMENTS

We thank the staff of Confederated Tribes of the Umatilla Indian Reservation for assistance with Pacific Lamprey collection and the Great Lakes Fishery Commission for the gift of the synthesized pheromones. We are grateful to Weiming Li at Michigan State University for providing the fish holding facility and water extraction materials. We also thank the three anonymous reviewers for their constructive criticisms and suggestions. This research was supported by the funding from Bonneville Power Administration and the U.S. Army Corps of Engineers, Portland District to D.A.C.