Primary structure of a novel gonadotropin-releasing hormone (GnRH) in the ovary of red swamp crayfish Procambarus clarkii

Gonadotropin-releasing hormone (GnRH) is a neuropeptide known to regulate and maintain reproductive functions and conserved in both vertebrate and invertebrate species. In this study, a GnRH peptide was isolated from the ovaries of red swamp crayfish, Procambarus clarkii, by using chromatographic and immunological methods. The form was proven to be a novel form of GnRH by determining its primary structure by chemical sequencing and mass spectrometry, and was designated as P. clarkii GnRH (pcGnRH). The primary structure of pcGnRH is pQSYHFSLGWKP-NH2, which is different from the known forms of the vertebrate and invertebrate GnRH family. Synthetic pcGnRH was biologically active, as it showed stimulative effects on ovarian maturation to crayfish. Our data supported the hypothesis that in crustacean there is GnRH synthesized locally in the ovary and playing an important role in the regulation of oocyte development. This is the first report on the isolation and characterization of GnRH-like peptide in crustacean.