Toxic Effects Of Heavy Mental Pb²⁺and Cu²⁺ To The Crassostrea Gigas

Cu²⁺and Pb²⁺are selected as contaminants to detect their acute toxicity actionand effects on the activities of SOD, CAT and GSH-Px in Crassostrea gigas which ischosen as the target organism and the main research contents include: studying thephysiological and biochemical effects of low-concentration and long-time sublethalstress of in the different tissues of the mussels （gills and digestive glands）; researchedthe difference in sensitivity to antioxidant responses in both tissues; discussed thepossible mechanism preliminarily.1. The acute toxicity of Cu²⁺and Pb²⁺on Crassostrea gigas.The Manila clam is exposed to different concentrations of Cu²⁺and Pb²⁺solution,then statistics the mortality of24h,48h,72h and96h. The median lethal concentration（LC50） is calculated through regression equation obtained by unit conversion.Theresults show that, the96h LC50of Pb²⁺is22.989mg/L. the96h LC50of Cu²⁺is21.748mg/L.2. The effect of Cu²⁺and Pb²⁺on Crassostrea gigas s activities of antioxidantenzymesAccording to the results of acute toxicity test, expose Crassostrea gigas indifferent concentrations of Cu²⁺（the control group,0.1mg/L,0.2mg/L,0.5mg/L） and Pb²⁺(control group,0.04mg/L,0.1mg/L.Sample mantle organization,visceral mass and muscle tissue at0d,3d,7d,12d,18d,25d.The results show that:Low concentrations of Cu²⁺induce the activities of all the three enzymes; Highconcentrations of Cu²⁺inhibit SOD,CAT and GPx conversely. For SOD、CAT andGSH-Px activity, the same sensitivity of three different organizations is mass>muscle tissue> gill, Pb²⁺duress significantly changed the activities of SOD,GPx andCAT. Pb²⁺induced the activities of all the three enzymes, the sensitivity of threedifferent organizations was viscera mass> muscle tissue> gill, The present studies showed that the activity of SOD，GPx and CAT in the Crassostrea gigas could beused as a monitoring index of heavy metal Pb²⁺pollution for water underexperimental conditions，but for actual breeding water，further studies need to becarried out later．4Preliminary studying on the mechanism of the effects of Cu²⁺and Pb²⁺stress onCrassostrea gigasIn a word, Cu²⁺and Pb²⁺stress results in the degree of lipid peroxidationincreased, the levels of reactive oxygene species increased and the oxidative stressgenerated, Meanwhile, the results show that the mussels’ digestive gland is moresensitive under long-time sublethal stress of Cu²⁺and Pb²⁺and it is the primary targetorgan. GPx activities,SOD and CAT· contents are very sensitive to the responses ofthe stress.