Isolation of maturational gonadotropin subunits from spotted seatrout (Cynoscion nebulosus) and development of a beta-subunit-directed radioimmunoassay for gonadotropin measurement in sciaenid fishes.
Maturational gonadotropin (GTH) subunits were isolated from pituitaries of the spotted seatrout (Cynoscion nebulosus), a marine perciform teleost, by ethanolic extraction and ion-exchange, gel-filtration, and reverse-phase chromatography. Partial amino acid sequencing of the N-terminal regions of the alpha and beta subunits indicated 60-80% identities with various carp and salmon GTH subunits. The spotted seatrout GTH beta-subunit was used as radioligand in a radioimmunoassay (RIA) with Atlantic croaker (Micropogonias undulatus) GTH antiserum. Pituitary extracts and plasmas from a variety of sciaenid fishes diluted parallel to the croaker GTH standard in the RIA. These data suggest that there is a high degree of immunological similarity among the GTH beta subunits of sciaenid fishes. The RIA measured increased levels of GTH in the plasmas of three species of sciaenid fishes, spotted seatrout, orangemouth corvina (Cynoscion xanthulus), and red drum (Sciaenops ocellatus), following injections of a luteinizing hormone-releasing hormone analog. The beta-subunit-directed GTH RIA increases considerably the number of species in which studies of GTH physiology can now be conducted.
Copeland
P A
PA
University of Texas, Marine Science Institute, Port Aransas, Austin 78373.
Thomas
P
P
D000595:Amino Acid Sequence; D000818:Animals; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005399:Fishes / Q000378:metabolism*; D006062:Gonadotropins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D015151:Immunoblotting; D007986:Luteinizing Hormone / Q000276:immunology / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010902:Pituitary Gland / Q000737:chemistry; D011863:Radioimmunoassay; D013045:Species Specificity; D014337:Trout / Q000378:metabolism*
D006062:Gonadotropins; D007986:Luteinizing Hormone