Study On The Damaged Effects On Sinopotamon Induced By Cadmium And The Protective Effects Of Low Molecular Weight Chitosan

The oxidative damage to the hepatopancreas, gill, heart and muscle induced by Cadmium in freshwater crab(Sinopotamon yangtsekiense), and the combination of low molecular weight chitosan (LMWC) with Cd2+were studied. The individuals were exposed to the normal control group, there groups of cadmium (29,58,87 mg/L) and three combined groups (58 mg/L Cd2++20 mg/L LMWC,58 Cd2++40 mg/L LMWC and 58 Cd2++80 mg/L LMWC). After 96 h treatment, the contents of protein carboyl(PCO) and DNA-protein crosslinks(DPC) coefficients were measured. The levels of nitric oxide(NO), the activities of inducible nitric oxide synthase(iNOS), two enzymes associated with calcium homeostasis(Na+-K+-ATPase and Ca2+-ATPase) in four tissues of S.yangtsekiense were assayed as well, aiming at investigating the impacts of Cd2+and the combined effects of LMWC on S.yangtsekiense. The method of real-time quantitative PCR was used to detect the mRNA expression levels of metallothionein(MT) in four tissues, in order to explore the mechanism of injury induced by Cadmium and the protective effects of LMWC The results showed that:(1) Cd2+significantly increased both PCO contents and DPC coefficients in four tissues, and the contents of PCO and DPC in hepatopancreas and gill increased significantly at 58 and 87 mg/L Cd2+, but the changes in heart and muscle were not significant, while the PCO contents and DPC in hepatopancreas, gill, heart and muscle of the samples were reduced when LMWC combined with Cd2+, and such effects were obviously promoted at higher concentrations (58 Cd2++40 mg/L LMWC and 58 Cd2++80 mg/L LMWC).(2) With increasing Cd2+concentration, the contents of NO and activities of iNOS in hepatopancreas and gill increased, while the alteration of contents of NO and iNOS were not obvious in heart and muscle of S.yangtsekiense compared with the control. Moreover, the contents of NO and iNOS in hepatopancreas and gill were markedly decreased in the groups of cadmium plus LMWC compared with the cadmium group, but there were not markedly changes in the heart and muscle.(3) Cadmium significantly inhibited activities of Na+-K+-ATPase and Ca2+-ATPase in hepatopancreas and gill, while the alteration of activities of Na+-K+-ATPase and Ca2+-ATPase were not significant in heart and muscle of S.yangtsekiense compared with the control. Moreover, the activities of Na+-K+-ATPase and Ca+-ATPase in hepatopancreas and gill were markedly increased in the groups of cadmium plus LMWC compared with the cadmium group, but there were not markedly changes in the heart and muscle of S.yangtsekiense.(4) Cadmium can significantly induce mRNA expressions of MT in hepatopancreas, gill and muscle, while the alteration of mRNA was not significant in heart of S.yangtsekiense compared with the control. Moreover, the mRNA expressions in hepatopancreas and gill were markedly decreased in the groups of cadmium plus LMWC compared with the cadmium group.Conclusions:(1) Cadmium increased PCO contents and DPC coefficients in four tissues of S.yangtsekiense, and LMWC may play a protective role in preventing S.yangtsekiense from the Cd2+-induced toxicity through decreasing.(2) Cadmium can inhibite activities of Na+-K+-ATPase and Ca2+-ATPase in four tissues of S. yangtsekiense. However the effects are different in various tissues. The combination treatment of LMWC and cadmium can increase the activities of Na+-K+-ATPase and Ca2+-ATPase in S. yangtsekiense in a certain range.(3) Cadmium can increase the contents of NO and activities of iNOS in four tissues of S. yangtsekiense. The combination treatments of LMWC and cadmium can decrease the contents of NO and activities of iNOS in S. yangtsekiense in a certain range.(4) Cadmium can induce MT mRNA expressions in four tissues of S. yangtsekiense. However, the effects vary from tissue to tissue. The combination treatments of LMWC and cadmium can decrease the expressions levels of MT in S.yangtsekiense in a certain range.