title: Distinctive metabolite profiles in in-migrating Sockeye salmon suggest sex-linked endocrine perturbation.
abstract: The health of Skeena River Sockeye salmon (Onchorhychus nerka) has been of increasing concern due to declining stock returns over the past decade. In the present work, in-migrating Sockeye from the 2008 run were evaluated using a mass spectrometry-based, targeted metabolomics platform. Our objectives were to (a) investigate natural changes in a subset of the hepatic metabolome arising from migration-associated changes in osmoregulation, locomotion, and gametogenesis, and (b) compare the resultant profiles with animals displaying altered hepatic vitellogenin A (vtg) expression at the spawning grounds, which was previously hypothesized as a marker of xenobiotic exposure. Of 203 metabolites monitored, 95 were consistently observed in Sockeye salmon livers and over half of these changed significantly during in-migration. Among the most dramatic changes in both sexes were a decrease in concentrations of taurine (a major organic osmolyte), carnitine (involved in fatty acid transport), and two major polyunsaturated fatty acids (eicosapentaenoic acid and docosahexaenoic acid). In females, an increase in amino acids was attributed to protein catabolism associated with vitellogenesis. Animals with atypical vtg mRNA expression demonstrated unusual hepatic amino acid, fatty acid, taurine, and carnitine profiles. The cause of these molecular perturbations remains unclear, but may include xenobiotic exposure, natural senescence, and/or interindividual variability. These data provide a benchmark for further investigation into the long-term health of migrating Skeena Sockeye.
authors.affiliation: AXYS Analytical Services Ltd. 2045 Mills Road West, Sidney, British Columbia V8L 5X2, Canada.
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Benskin
authors.forename: Michael G
authors.initials: MG
authors.lastname: Ikonomou
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Nik
authors.initials: N
authors.lastname: Veldhoen
authors.forename: Cory
authors.initials: C
authors.lastname: Dubetz
authors.forename: Caren C
authors.initials: CC
authors.lastname: Helbing
authors.forename: John R
authors.initials: JR
authors.lastname: Cosgrove
mesh_terms: D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D002331:Carnitine / Q000737:chemistry; D004703:Endocrine System / Q000187:drug effects*; D004784:Environmental Monitoring; D005227:Fatty Acids / Q000737:chemistry; D005260:Female; D005838:Genotype; D008099:Liver / Q000378:metabolism; D008297:Male; D055442:Metabolome; D010641:Phenotype; D045483:Rivers; D012474:Salmon / Q000378:metabolism*; D012737:Sex Factors; D013654:Taurine / Q000737:chemistry; D014018:Tissue Distribution; D015262:Xenobiotics / Q000737:chemistry
chemical_list: D005227:Fatty Acids; D015262:Xenobiotics; D013654:Taurine; D002331:Carnitine