Effect Of Cu²⁺ Stress On The Protein Oxidative Damage Of The Crayfish Procambarus Clarkii

In recent years, with the development of industry and agriculture, a lot of heavy metal pollutants pulled into water and the pollution of water become seriously. "Environmental Status of 2012 in China" showed that copper is the main heavy metal pollutants in coastal water, rivers and lakes of our country.Because of the abuse of copper sulfate, copper has become a major source of pollutants in aquaculture.Procambarus clarkii often used as potential water pollution indicator organisms because it has a wide acceptability and can survive even in seriously polluted water.In this study, Procambarus clarkii used as the research object and Cu2+ used as the stress factor.The crayfishes were exposed to various concentrations of Cu2+(0,0.5,1.0,3.0,5.0 and 10.0mg/L) until 96h according to the 96h LC50 values (30mg/L) measured previously.After exposure 24,48,72 and 96h, detection the effect of Cu2+ on the lever of ROS in hemolymph, hepatopancreas, gill and muscle, hemocyanin content in hemolymph, antioxidant defense capacity (T-AOC capacity and GSH-Px activity) and oxidative protein damage (PCO content and DPC lever), combined with the histopathological of hepatopancreas and gill, it design to provide a theoretical basis for the mechanism of toxicity of copper on crayfish. The results showed that:(1)With the Cu2+ concentration increased and exposure time prolonged, crayfish hemolymph ROS levels was increased first then deceased; serum hemocyanin increased first then stabilized, and finally increases significantly; the T-AOC ability and GSH-Px activity of serum showed a similar tendency of rising first and then going down.A short period of exposure induced a significant increase, T-AOC capacity and GSH-Px activity of serum were suppressed after time extended.The experiment indicates that Cu2+ induced crayfish ROS content increase, resulting in oxidative stress.(2)After exposure to Cu2+, the crayfish produced excess ROS, resulting in antioxidant enzyme GSH-Px activity and T-AOC capability suppressed, PCO content and DPC increase significantly. The result indicates that Cu2+ can cause protein oxidative damage of crayfish.(3)After exposure to Cu2+, the hepatopancreas tubule basement of crayfish was thickening, deformation and arching, Vacuoles increased, simple columnar cell enlarged, the number of blood cells increased in the sinuses, the intracellular substances leakage, cell debris appeared in lumen of tubules. The respiratory epithelial cells swelled of the gill, gill was fracture, a large number of cell necrosis, and necrotic cell micro-cavity blood appeared, indicating that Cu2+exposure caused crayfish hepatopancreas and gill produce significant structural damage.When the crayfish antioxidant defense system can not remove excess ROS, GSH-Px activity and T-AOC ability were suppressed.In summary, the mechanism of Cu2+induced crayfish proteins oxidation damage may be related with the generation of ROS.In order to maintain the balance of oxidation and anti-oxidation, the GSH-Px activity and T-AOC ability increased.When the crayfish antioxidant defense system can not remove excess ROS, GSH-Px activity and T-AOC ability were suppressed. Protein is the most abundant biological macromolecules in cells and is the main target of ROS.Tissue protein oxidative damage may break the respiration of gill and secretion of digestive juices, absorbing nutrients, detoxification and other physiological functions of hepatopancreas.This may be the main mechanism of copper exposure caused toxic effects and affected the health of the Procambarus clarkii.