title: Molecular characterization of the gonadal kisspeptin system: Cloning, tissue distribution, gene expression analysis and localization in sablefish (Anoplopoma fimbria).
abstract: The kisspeptin system plays pivotal roles in the regulation of vertebrate reproduction. Classically, kisspeptin produced in the brain stimulates brain gonadotropin-releasing hormone signaling, which in turn activates the pituitary-gonad axis. Expression of the kisspeptin system has also been documented in peripheral tissues, including gonads of mammals and fishes. However, the fish gonadal kisspeptin system remained uncharacterized. Herein we report identification and characterization of four kisspeptin system mRNAs (kisspeptin 1 (kiss1), kiss2, and G protein-coupled receptor 54-1 (gpr54-1) and gpr54-2) in sablefish, Anoplopoma fimbria. Sablefish predicted protein sequences were highly similar to those of other marine teleosts, but less so to freshwater teleosts. Tissue distribution analyses revealed that all four kisspeptin-system transcripts were expressed in both brain and gonad. However, kiss2 was the predominant transcript in the gonads and the only transcript detected in ovulated eggs. Ontogenetic analysis of kiss2 expression in juvenile sablefish gonads demonstrated that levels were low during sex differentiation but increased with fish size and gonadal development. Dramatic increases in kiss2 mRNA occurred during primary oocyte growth, while levels remained relatively low in testes. In situ hybridization revealed that kiss2 mRNA was localized to cytoplasm of perinucleolus stage oocytes, suggesting it could play a local role in oogenesis or could be synthesized and stored within oocytes as maternal mRNA. This represents the first study to focus on the gonadal kisspeptin system in fishes and provides important tools for further investigation of both the gonadal and brain kisspeptin systems in sablefish.
authors.affiliation: Undergraduate Research Program, University of Washington, 171 Mary Gates Hall, Seattle, WA 98195-2803, USA.
authors.forename: Marian R
authors.initials: MR
authors.lastname: Fairgrieve
authors.affiliation: School of Aquatic and Fishery Sciences, University of Washington, 1122 NE Boat St, Seattle, WA 98195-5020, USA.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Shibata
authors.affiliation: Frank Orth and Associates, Under Contract to Northwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 2725 Montlake Blvd E, Seattle, WA 98112, USA.
authors.forename: Elizabeth K
authors.initials: EK
authors.lastname: Smith
authors.affiliation: Frank Orth and Associates, Under Contract to Northwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 2725 Montlake Blvd E, Seattle, WA 98112, USA.
authors.forename: Edward S
authors.initials: ES
authors.lastname: Hayman
authors.affiliation: Environmental and Fisheries Sciences Division, Northwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 2725 Montlake Blvd E, Seattle, WA 98112, USA; Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA. Electronic address: adam.luckenbach@noaa.gov.
authors.forename: J Adam
authors.initials: JA
authors.lastname: Luckenbach
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D003001:Cloning, Molecular; D006066:Gonads / Q000378:metabolism*; D059648:Kisspeptins / Q000235:genetics / Q000378:metabolism*; D010473:Perciformes / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D012098:Reproduction; D012733:Sex Differentiation / Q000502:physiology*
chemical_list: D059648:Kisspeptins; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled
keywords: Gonadal sex differentiation; Kisspeptin system; Ovarian development; Primary oocyte growth; Reproduction; Teleost