Antioxidant responses in Mytilus galloprovincialis exposed to copper

Abstract

A laboratory experiment was conducted to investigate correlations between Cu concentrations in Mytilus galloprovincialis and antioxidant responses. The results of the experiment indicated that Cu accumulated in M galloprovincialis during a 21-day exposure period. Mussels exposed to low dosages (40 mu g/L) of Cu resulted in a 4-fold increase in Cu bioaccumulation, whereas mussels exposed to high dosages (100 mu g/L) of Cu, resulted in a 10-fold increase. The potential of oxidative stress as a biomarker was investigated using a battery of antioxidant assays/methodologies. The total antioxidant capacity was measured using FRAP and ORAC, anti-oxidant enzyme activity was determined by measuring catalase, superoxide dismutase, while the oxidative stress status was assessed by measuring the glutathione (GSH) content and lipid peroxidation marker levels of conjugated dienes (CD) and thio-barbituric acid reactive substances (TBARS). The results showed that M. galloprovincialis exposed to high dosages of Cu had significantly (P<0.05) increased levels of TBARS, indicative of increased oxidative stress. Interestingly, for GSH levels and ORAC capacity, at day 21, both were significantly higher (P<0.05) than at the start of the experiment. The results suggested that oxidative stress responses in M. galloprovincialis could be considered as biomarkers of toxicity in southern Africa.