Two homologs of rho-class and polymorphism in alpha-class glutathione S-transferase genes in the liver of three tilapias

• The differentially expressed of GSTA in tilapias exposed to MC-LR were detected.
• Three single nucleotide polymorphisms of GSTA genes were identified in tilapia.
• Two homologs of GSTR were identified.

To clarify detoxification metabolism of tilapia, a natural and biological control for removing the leftover toxicants in fresh water, sequence structure, expression profile and polymorphisms of members of glutathione S-transferase (GST) genes were analyzed in Nile tilapia, blue tilapia and their hybrid. Full-length mRNA sequences of alpha-class GST (GSTA) and two homologs of rho-class GST (GSTR) were identified. Sequence analysis confirmed the similarity in conserved domain regions and their phylogenetic relationships with GST genes in other fishes. In addition, three single nucleotide polymorphisms of GSTA genes were identified in the three populations, two (C266T and G525A) of which showed significant association. The relative mRNA expression of GSTA gene was significantly (P<0.05) increased in the liver of Nile tilapia at 24 h post-injection of MC-LR, significantly (P<0.05) decreased in blue tilapia whereas slightly decreased (P>0.05) in hybrid tilapia.