Gonadotropin-releasing hormone from thai catfish: chromatographic and physiological studies.
Two forms of immunoreactive gonadotropin-releasing hormone (GnRH) were extracted from brain-pituitary tissues of Thai catfish, Clarias macrocephalus and C. batrachus. The peptides were detected using high performance liquid chromatography (HPLC) and radioimmunoassay (RIA). In both the HPLC systems, catfish GnRH-I eluted earlier than catfish GnRH-II and also eluted before the synthetic standards of mammalian, lamprey, chicken I, chicken II, and salmon GnRH. Hence, catfish GnRH-I appears to be the most hydrophilic GnRH family member because of this early elution from the HPLC. Catfish GnRH-II eluted in a position similar to that of chicken GnRH-II. This study suggests that catfish GnRH-I is a novel form of GnRH, whereas catfish GnRH-II is the same as chicken GnRH-II. Indirect evidence suggests that the catfish molecule is 10 amino acids in length and has an amide at the C-terminus. Moreover, the novel catfish GnRH appears to be different within the domain of amino acids 5 to 10 compared with mammalian GnRH because it is not recognized by antiserum B-6. An injection of native chicken GnRH-II was more effective than salmon or mammalian GnRH for induced ovulation in C. macrocephalus.
Ngamvongchon
S
S
Department of Biology, University of Victoria, British Columbia, Canada.
Sherwood
N M
NM
Warby
C M
CM
Rivier
J E
JE
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D002397:Catfishes; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D005260:Female; D005306:Fertilization / Q000187:drug effects; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives / Q000302:isolation & purification / Q000494:pharmacology* / Q000502:physiology*; D008297:Male; D008969:Molecular Sequence Data; D010060:Ovulation / Q000187:drug effects; D010902:Pituitary Gland / Q000378:metabolism; D011863:Radioimmunoassay
D007987:Gonadotropin-Releasing Hormone