title: Biosynthesis and release of pheromonal bile salts in mature male sea lamprey.
abstract: BACKGROUND
  In vertebrates, bile salts are primarily synthesized in the liver and secreted into the intestine where they aid in absorption of dietary fats. Small amounts of bile salts that are not reabsorbed into enterohepatic circulation are excreted with waste. In sexually mature male sea lamprey (Petromyzon marinus L.) a bile salt is released in large amounts across gill epithelia into water where it functions as a pheromone. We postulate that the release of this pheromone is associated with a dramatic increase in its biosynthesis and transport to the gills upon sexual maturation.
  
  
  RESULTS
  We show an 8000-fold increase in transcription of cyp7a1, a three-fold increase in transcription of cyp27a1, and a six-fold increase in transcription of cyp8b1 in the liver of mature male sea lamprey over immature male adults. LC-MS/MS data on tissue-specific distribution and release rates of bile salts from mature males show a high concentration of petromyzonol sulfate (PZS) in the liver and gills of mature males. 3-keto petromyzonol sulfate (3kPZS, known as a male sex pheromone) is the primary compound released from gills, suggesting a conversion of PZS to 3kPZS in the gill epithelium. The PZS to 3kPZS conversion is supported by greater expression of hsd3b7 in gill epithelium. High expression of sult2b1 and sult2a1 in gill epithelia of mature males, and tissue-specific expression of bile salt transporters such as bsep, slc10a1, and slc10a2, suggest additional sulfation and transport of bile salts that are dependent upon maturation state.
  
  
  CONCLUSIONS
  This report presents a rare example where specific genes associated with biosynthesis and release of a sexual pheromone are dramatically upregulated upon sexual maturation in a vertebrate. We provide a well characterized example of a complex mechanism of bile salt biosynthesis and excretion that has likely evolved for an additional function of bile salts as a mating pheromone.
authors.forename: Cory O
authors.initials: CO
authors.lastname: Brant
authors.forename: Yu-Wen
authors.initials: YW
authors.lastname: Chung-Davidson
authors.forename: Ke
authors.initials: K
authors.lastname: Li
authors.forename: Anne M
authors.initials: AM
authors.lastname: Scott
authors.affiliation: Department of Fisheries and Wildlife, Michigan State University, Room 13 Natural Resources Building, 480 Wilson Road, 48824 East Lansing, MI, USA. Liweim@msu.edu.
authors.forename: Weiming
authors.initials: W
authors.lastname: Li
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000096:biosynthesis* / Q000378:metabolism*; D053493:Cholestanetriol 26-Monooxygenase / Q000235:genetics / Q000378:metabolism; D002790:Cholesterol 7-alpha-Hydroxylase / Q000235:genetics / Q000378:metabolism; D002793:Cholic Acids / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D005880:Gills / Q000378:metabolism; D006913:Hydroxysteroid Dehydrogenases / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000201:enzymology / Q000378:metabolism; D008297:Male; D048428:Petromyzon / Q000378:metabolism*; D012724:Sex Attractants / Q000096:biosynthesis* / Q000378:metabolism; D013253:Steroid 12-alpha-Hydroxylase / Q000235:genetics / Q000378:metabolism; D015238:Sulfotransferases / Q000235:genetics / Q000378:metabolism; D053719:Tandem Mass Spectrometry; D014018:Tissue Distribution; D014158:Transcription, Genetic
chemical_list: D001647:Bile Acids and Salts; D002793:Cholic Acids; D012724:Sex Attractants; C500317:petromyzonol sulfate; D006913:Hydroxysteroid Dehydrogenases; D002790:Cholesterol 7-alpha-Hydroxylase; D053493:Cholestanetriol 26-Monooxygenase; D013253:Steroid 12-alpha-Hydroxylase; D015238:Sulfotransferases