Investigations of Novel Unsaturated Bile Salts of Male Sea Lamprey as Potential Chemical Cues

Sulfated bile salts function as chemical cues that coordinate reproduction in sea lamprey, Petromyzon marinus. 7 alpha, 12 alpha, 24-trihydroxy-5 alpha-cholan-3-one 24-sulfate (3kPZS) is the most abundant known bile salt released by sexually mature male sea lampreys and attracts ovulated females. However, previous studies showed that the male-produced pheromone consists of unidentified components in addition to 3kPZS. Here, analysis of water conditioned with mature male sea lampreys indicated the presence of 4 oxidized, unsaturated compounds with molecular weights of 466 Da, 468 Da, and 2 of 470 Da. These compounds were not detectable in water conditioned with immature male sea lampreys. By using mass spectrometry, 4 A-ring unsaturated sulfated bile salts were tentatively identified from male washings as 2 4-ene, a 1-ene, and a 1,4-diene analogs. These were synthesized to determine if they attracted ovulated female sea lampreys to spawning nests in natural streams. One of the novel synthetic bile salts, 3 keto-1-ene PZS, attracted ovulated females to the point of application at a concentration of 10(-12) M. This study reveals the structural diversity of bile salts in sea lamprey, some of which have been demonstrated to be pheromonal cues.