Glutathione-S-transferases (GSTs) are crucial enzymes in the cell detoxification system. They catalyze the nucleophilic attack of glutathione (GSH) on electrophilic substrates to produce less toxic and more water soluble compounds. Since GSTs are involved in detoxification of various environmental pollutants, measurement of GST activity in aquatic organisms have been frequently used as an ecotoxicological biomarker. However, comprehensive insight into the GST family in teleosts has not yen been given. Therefore, the aim of our study was initial characterization of glutathione-S-transferase superfamily in zebrafish (Danio rerio) using phylogenetic analysis and tissue expression profiling. NCBI and ENSEMBL databases were searched for GST members in human, zebrafish and stickleback. Phylogenetic tree of GST superfamily was constructed in PhyML Software, while qPCR was employed to investigate expression of GST genes in six tissues of adult female zebrafish (liver, kidney, gills, intestine, brain and ovaries). Phylogenetic analysis revealed that GST superfamily in zebrafish, like in human consists of three groups: (1) cytosolic Gsta, Gstm, Gstp, Gstt, Gstz and Gsto ; (2) mitochondrial Gstk and (3) microsomal Mgst group. Altogether, we have identified 26 zebrafish GSTs on the genome level, and quantified transcript levels of 11 chosen genes. Tissue distribution analysis revealed that three members of Gstm (DrGstm1, DrGstm2 and DrGstm3) and two members of Gstp (DrGstp1 and DrGstp2) family are highly expressed in all tissues. Members of DrGsta have higher expression in intestine, followed by lower expression in liver. DrGstt members have low expression throughout all tissues, while DrGsto2 shows overall higher expression in comparison to DrGsto1, specifically in ovaries. In summary, the described comprehensive analysis of GST superfamily in zebrafish represents the first step towards characterization of toxicologically most relevant GST members in teleosts.

Biology