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.