Cadmium And Cadmium, Zinc And Joint Toxic Effects On The Goldfish

With the development of industrial society, heavy metal pollution becomes worse and worse. In this paper, we investigated the effects of Cd²⁺ and Zn²⁺ on DNA damage, frequency of abnormal nucleus of erythrocytes and antioxidant defense system.In this paper , the activities of Peroxidase ,catalase ,MDA content and T-AOC in goldfish coerced by different concentrations of with Cd²⁺ and Zn²⁺ in 168h was detected. The results showed the activities of Peroxidase and catalase of low Cd²⁺ concentrations groups wound increase in the early period, which may probably come about as result of the "Toxic excitement effect". Then the activities decreased and increased again as the further exposure. While the activities of Peroxidase and catalase would be lower in all selected concentrations ,compared to the single Cd²⁺ treated, when coerced by Cd²⁺ and Zn²⁺ .so the joined toxicity of Cd²⁺ and Zn²⁺ was synergistic. By determining the content of malondialdehyde(MDA),we found the lipid peroxidation occurred in the high and middle Cd²⁺ concentrations,and with the exposure time prolonged, the content of MDA increased significantly (P<0.05) , while significant differences(P<0.001)in LPO were found after 72 hours when compared to controls, suggesting oxidative damage severely. Compared to the control group, the total antioxidant capacity of the low Cd²⁺ concentration group declined in the early period, it resumed then and began to declined again with the exposure time continue to increase. With the high and middle Cd²⁺ concentrations inhibiting the total antioxidant capacity, the inhibiting strength will increase with the prolonging of the exposure time and the concentration enhancing . In the high concentration of safe-zinc group antioxidant capacity were higher than the corresponding increase of cadmium single group performance for the antagonistic effect.Inducement of abnormal nucleus of erythrocytes of goldfish by the Cd²⁺ was studied at various concentration and exposure times. The result indicated that frequency of micronuclear and nuclear anomalies of each concentration group for the goldfish exposed to were higher than those of the control group (P<0.01).The damage effects of heavy metal Cd²⁺ with different concentrations on nuclear DNA in goldfish were studied by agarose gel electrophoresis.The result indicated :the level of DNA damage in each concentration group for the goldfish exposed to Cd²⁺ was significantly higher than that of control group and increased gradually with the dose increasing of in the same exposure period. So it existed dose-effect. The level of damage in each concentration groups for the goldfish exposed to Cd²⁺ and Zn²⁺ was all lower than that of single Cd²⁺ groups, so Zn²⁺ in safe concentration may antagonize the damage.For more credibility of the result, three biomarker is signed out in our experiment. Through detecting the number of erythrocytes nucleus anomalies, the level of DNA damage and the acticity of antioxidase, the toxicity of Cd²⁺ is evaluated.