IDENTIFICATION OF A PUTATIVE GnlH GENE AND ITS EXPRESSION AT DIFFERENT REPRODUCTIVE PHASES IN THE NILE TILAPIA Oreochromis niloticus

摘要

Gonadotropin-inhibitory hormone (GnlH) has been found to inhibit the synthesis and release of gonadotropin (GTH) in the regulatory system of avian and mammalian reproduction (Tsutsui et al. 2000; Ubuka et al. 2008; 2009). It was originally identifiedin the brain of a quail as a novel hypothalamic neuropeptide with a C-terminal Arg-Phe-NH2 motif (RFamide peptide) (Tsutsui et al. 2000). Homologs of this peptide have been identified in several model fish species such as goldfish (Carassius auratus) andzebrafish (Danio rerio), and their function with regards to the regulation of gonadotropin release are recently under intense study (Sawada et al. 2002; Zhang et al. 2010). Understanding GnlH system could be particularly useful in some aquaculture species with problems of frequent reproduction and/or precautious sexual maturation. However, GnlH system in such species has not been studied yet. In this study, we have identified a pupative GnlH gene and examined its expression at different reproductive phases together with gonadotropin subunit genes (FSH-0 and LH-|3) in the Nile tilapia (Oreochromis niloticus).