Regulative mechanism of Ce3+ relieves DNA damage caused by Cd2+ in the kidney of silver crucian carp

The mechanism of Cd²⁺ on the DNA cleavage and Ce³⁺ on the DNA repair in the kidney of silver crucian carp (Carassius auratus gibelio) is investigated by agarose gel electrophoresis methods and assaying biochemical indexes. It proves that Cd²⁺ induces the classical laddering degradation of DNA in vivo, but DNA cleavage is repaired after injecting with a low Ce³⁺ concentration under various Cd²⁺ concentrations. The DNA cleavage caused by Cd²⁺ is the result of the activation of deoxyribonuclease (DNase) and accumulation of reactive oxygen species (ROS), and Cd²⁺ destroys the antioxidant system, which diminishes the activities of superoxide dismutase, catalase, and peroxidase, and the increase of the lipid peroxidation (LPO) level. However, Ce³⁺ could inhibit activation of Cd²⁺ on DNase activity, relieve inhibition of Cd²⁺ on activities of the antioxidant enzyme, and diminish ROS accumulation. The results show that Ce³⁺ could relieve the toxicity of Cd²⁺ to silver crucian carp.