Molecular characterization and expression profiling of arsenic mediated stress-responsive genes in Dawkinsia tambraparniei (Silas, 1954)

An endemic fish Dawkinsia tambraparniei in River Tamiraparani happen to extinct for reason of anthropogenic activity and natural events that occurs. Among them, heavy metal arsenic stands as major toxic contained by aquatic systems until date. Therefore, the present study intended to explore the impacts of (As) heavy metal on D. tambraparniei through molecular characterization and expression profiling of stress responsive genes. Following, lethal concentration (LC 50 ) of arsenic trioxide (As 2 O 3 ) and sodium arsenite (NaAsO 2 ) was determined by probit analysis. Then, fishes were exposed for 42 days with As 2 O 3 (22.60 ppm) and NaAsO 2 (31.65 ppm) with control (0.0 ppm). Subsequently, expression profiling of Mt , p53, and superoxide dismutase genes was carried out in brain, heart and liver tissues through qPCR analysis. Overall, the obtained results showed notable expression level of As 2 O 3 treated fish heart shows Mt expression at 42 days while in NaAsO 2 expression fold was higher in 28 days. Similarly, As 2 O 3 treated fish brain displays Mt expression at 28 days. In NaAsO 2 group Mt lacks expression in brain. 14 days of exposure to As 2 O 3 drastically increase the expression of p53 gene compared with control brain tissue, whereas significantly elevated expression was found in the NaAsO 2 exposed heart and liver. Higher level of p53 gene expression was observed in brine by As 2 O 3 while compared with NaAsO 2 exposed heart and liver on the day 14. Henceforward, the present study proposed that expression profiling and stress analysis of As contamination significantly impact the gene expression throw light on detecting the heavy metals contamination in freshwater ecosystem for its forthright application and analysis.