Effects on DNA and antioxidant system of Anabas Testudineus on Experimental Exposure to a Sublethal Concentration of Methylmercury
Mercury is the most toxic in the organic form like methylmercury (MeHg), with an ability to accumulate in the cells of aquatic organisms like fish. This has been known to adversely affect the functions of almost every aspect of life. This study examined the effects of MeHg exposure on certain antioxidant defences in the liver and muscle of climbing perch (Anabas testudineus) adults and juveniles; the effect on DNA of erythrocytes were also studied. After 15 d of MeHg exposure (87.6 μg L-1), the effect of MeHg on DNA of the fish were analysed using comet assay and the activities of SOD (superoxide dismutase), catalase (CAT) and glutathione (GSH) alongwith lipid peroxidation levels (LPO) in the form of TBARS were used as antioxidant markers. The juvenile erythrocytes showed more DNA damage in the form of comets than adults. The activities of SOD significantly increased in all the experimental groups and tissues whereas catalase (CAT) activity increased in adult liver and musclesbut juvenile liver reported a decrease. Glutathione (GSH) levels showed difference in induction depending on the age of the fish with adult liver and muscle showing decrease and juveniles showing significant increase at 15 days of exposure. whereas exposure to MeHg did not remarkably affect CAT activity The levels of lipid peroxidation (LPO) increased in a time dependent manner showing tissue specificity with the higher levels in the liver than muscles. Overall, higher sensitivity to oxidative stress induced by MeHg was detected in the liver than the muscle. These findings improve our understanding of the tissue-specific accumulation of heavy metals and their roles in antioxidant responses in marine fish subjected to MeHg exposure.
