Abstract
C/EBP [CCAAT/enhancer-binding protein]-homologous protein gene (chop) which plays an important role in endoplasmic reticulum stress-induced apoptosis, was investigated here by RACE and qPCR in an aquaculture animal for the first time. The full-length cDNA sequences of loach (Misgurnus anguillicaudatus) chop were 2533bp, encoding 266 amino acids. The expression levels of loach chop changed obviously during different early life stages, and the highest appeared at the 8-cell stage. Among different tissues, loach chop predominantly expressed in gill, spleen and gonad. Then, we performed a hydrogen peroxide (H2O2, a common-used disinfectant) stress trial to explore the role of loach chop, with three different concentrations (0 μM, 50 μM and 100 μM) of H2O2. Half of the loaches from the 100 μM group were dead, while all loaches from the other two treatment groups were alive. The activities of CAT, SOD and GPX in loach gill, liver and spleen decreased with extended stress time and increased H2O2 concentration. The expression levels of gill chop in loaches from the 100 μM group were significantly higher than those from the other two treatment groups between 12 and 24 hours of exposure. atf4 and bax, two proapoptotic genes, were significantly up-regulated in gills of loaches from the 100 μM group compared to the other two groups 18 hours and 24 hours after treatment, while bcl2, an antiapoptotic gene, presented an opposite trend. These results indicated a close relationship between H2O2 stress and fish apoptosis, and loach chop played an important role in H2O2 stress response.