Anoxia tolerance and antioxidant defences in the green-lipped mussel Perna viridis (Linnaeus, 1758) under acute cadmium exposure

The survival to anoxia was measured from green-lipped mussel Perna viridis after of exposure to 50 mu g L-1 cadmium (Cd) during seven days, followed by a recuperation period in the sea during 21 days. The levels of Cd, and oxidative stress biomarkers as metallothioneins (MT), reduced glutathione (GSH) and lipid peroxidation (TBARS), and maximal activities of catalase (CAT), glutathione reductase (GR) and glutathione-S- transferase (GST) were calculated in the digestive gland in experimental organisms. The Cd-exposed organisms showed an anoxia tolerance reduced; however, those organisms recovered in the sea showed a survival time to anoxia major in contrast to control organisms. The Cd-exposed organisms revealed a significant increase of MT and CAT correlated with Cd uptake. The Cd-preexposure and sea-transplanted mussels showed a significant reduction of metal accumulated, whereas the levels of MT was maintain heightened. Both, Cddepurated and non-depurated organisms did not exhibit significant differences among the biomarkers of oxidative stress: TBARS, GSH and enzymes tested. The uptake Cd possibly affected some biochemical mechanisms related to anoxia tolerance, however the high levels of MT in the pre-exposure and recuperated organisms, could be condition the protection against Cd-toxicity and indirectly a resistance to prolonged anoxia.