GHR and IGF-I gene expression and production characteristics associated with GH gene polymorphism in Nile tilapia

The aim of this study was to investigate the effects of genotype on gene expression and performance characteristics in crossbred GIFT × Chitralada tilapia. We compared the effects of GH single band (GHsb) and GH double band (GHdb) genotypes on performance characteristics, growth hormone receptor (GHR) and insulin-like growth factor I (IGF-I) gene expression in the liver and white muscle. The experiment was conducted in a 2 × 2 factorial design with two categories of weight (20-35 g and 40-70 g) and two genotypes (GHsb and GHdb). Fin fragments were collected for genotyping, while the liver and white muscle samples were collected to analyze gene expression via qRT-PCR. GHdb genotype animals presented greater body weight, empty weight, weight of viscera, and filet weight and length, thereby indicating that GH variation may correlate with performance characteristics. Although some of the phenotypes we measured were correlated with genotype, we cannot say that it is due to the direct effect of the studied polymorphism. However, we recommend further studies be conducted to reveal the genetic nature of this polymorphism.