Isolation and expression of tilapia (Oreochromis niloticus) serine 8-type GnRH coding and regulatory sequences

The complete Serine 8-type gonadotropin releasing hormone (GnRH) coding sequence with a substantial 5-prime regulatory sequence (5 kb) has been isolated and characterised in Nile Tilapia (Oreochromis niloticus) from a relevant genomic library. The primary structure of the protein precursor was identified for this gene. The promoter efficacy has been tested using 0.6 kb of the GnRH promoter driving a lacZ reporter gene in both cultured spleen cells and transiently expressing zebrafish. In the cell transfection experiments, the average level of beta-galactosidase activity in transfected cells was more than 2.1 (P<0.05) times higher than the control promoter-less vector in five independent cultures indicating that the 0.6 GnRH/lacZ construct is able to express in spleen cells. In addition, the transient expression of the lacZ gene was detected in the brain of G0 zebrafish embryos (Danio rerio) 4 days after fertilisation following egg injection with the construct, which demonstrated the efficacy of the tilapia GnRH promoter.