Multiple molecular forms of gonadotropin-releasing hormone in the brain of an elasmobranch: evidence for IR-lamprey GnRH.
These studies investigated brains of skate, Raja erinacea (order Rajiformes, class Chondrichthyes), for gonadotropin-releasing hormone (GnRH) peptides by chromatograph and immunoreactivity with region-specific antisera raised against mammalian GnRH and lamprey GnRH. The region-specific antibody to lamprey GnRH-I was produced following conjugation to bovine serum albumin using the bis-diazotized benzidine method. This antibody was characterized by assaying a range of increasing dilutions of the known vertebrate GnRHs, as well as analogs to lamprey GnRH-I. Two analogs, lamprey [Phe2]GnRH-I and lamprey [Leu7]GnRH-I, were synthesized by solid phase peptide synthesis using a benzhydrylamine resin as the supporting medium and purified by chromatography. This antibody demonstrated less than 0.01% cross-reactivity with all GnRH peptides tested, suggesting a highly specific antibody with a region of amino acids 2-8 that appears essential for binding. In the skate brain, five immunoreactive (IR) GnRH forms were detected, four of which eluted in the same positions as synthetic mammal and chicken GnRH-I (which coelute): lamprey GnRH-I, salmon and chicken GnRH-II, and one that was an unidentified form. A minor peak coeluted with lamprey GnRH-III. The major form in the skate brain is considered to have eluted with synthetic mammalian GnRH. These studies confirm an earlier report of an IR-mammalian GnRH peptide and provide new evidence for IR-lamprey GnRH in the brain of an elasmobranch.
Calvin
J L
JL
Department of Biochemistry, University of New Hampshire, Durham 03824.
Slater
C H
CH
Bolduc
T G
TG
Laudano
A P
AP
Sower
S A
SA
D000818:Animals; D001923:Brain Chemistry / Q000502:physiology; D007987:Gonadotropin-Releasing Hormone / Q000737:chemistry*; D007798:Lampreys / Q000276:immunology*; D011817:Rabbits; D011863:Radioimmunoassay; D012860:Skates, Fish / Q000378:metabolism*
D007987:Gonadotropin-Releasing Hormone