title: Gonadotropin-releasing hormone (GnRH) in ancient teleosts, the bonytongue fishes: putative origin of salmon GnRH.
abstract: The molecular forms of gonadotropin-releasing hormone (GnRH) were examined in the bonytongue fishes (Osteoglossomorpha), one of the most ancient living teleost groups. These fish represent a phylogenetic link between the early ray-finned fishes and the modern teleosts. Five representative species from four of six bonytongue families were examined for GnRH using high-performance liquid chromatography and radioimmunoassay techniques with antisera raised against salmon (s), chicken-II (c-II), and mammalian (m) forms of GnRH. Salmon GnRH and cGnRH-II were identified in four of the species (arawana, elephantnose, false featherfin, Asiatic featherfin) whereas in the butterfly fish, mGnRH and cGnRH-II were identified. Our data suggest that teleosts such as eels and butterfly fish, which have mGnRH like that of even earlier ray-finned fishes, may have evolved before fish with sGnRH. We also suggest that sGnRH first appeared in the Osteoglossomorpha. The phylogenetic relationship of the eels (Anguillidae), butterfly fish (Pantodontidae), and bonytongue fish among other teleosts needs to be reexamined using additional characteristics.
authors.affiliation: Department of Biology, University of Victoria, Victoria, British Columbia, V8W 2Y2.
authors.forename: D F
authors.initials: DF
authors.lastname: O'neill
authors.forename: J F
authors.initials: JF
authors.lastname: Powell
authors.forename: E M
authors.initials: EM
authors.lastname: Standen
authors.forename: J H
authors.initials: JH
authors.lastname: Youson
authors.forename: C M
authors.initials: CM
authors.lastname: Warby
authors.forename: N M
authors.initials: NM
authors.lastname: Sherwood
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001923:Brain Chemistry; D002851:Chromatography, High Pressure Liquid; D005399:Fishes / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D010902:Pituitary Gland / Q000378:metabolism; D011863:Radioimmunoassay; D012474:Salmon / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D007987:Gonadotropin-Releasing Hormone