Effects of Waterborne Cadmium Exposure on Its Internal Distribution in Meretrix meretrix and Detoxification by Metallothionein and Antioxidant Enzymes

作者：Yao Huang, Hongchao Tang, Jian-Yu Jin, Meng bi Fan, Alan K. Chang, Xueping Ying · 发表于：Frontiers in Marine Science · 年份：2020 · DOI：10.3389/fmars.2020.00502 · 被引用次数：25 · 研究领域：Environmental Toxicology and Ecotoxicology、Heavy Metal Exposure and Toxicity、Mercury impact and mitigation studies

Cadmium (Cd), one of the most toxic metals found in inshore sediments of China, is a persistent environmental contaminant capable of exerting irreversible toxic effect on aquatic organisms and their associated ecosystems. Although Cd is known to be toxic to marine animals, the underlying mechanism of this toxicity is not clear. In this study, Meretrix meretrix, a commercially and ecologically important species of clam, was exposed to different concentrations of cadmium chloride (0, 1.5, 3, 6, 12 mg L-1) for 5 days, and the levels of Cd accumulation, antioxidant enzyme activity and expression of metallothionein (MT) in the hepatopancreas, gill, foot and mantle were evaluated. The results revealed a sharp increase in Cd accumulation in the tissues in response to increased Cd2+ concentrations in the water, and significant differences in Cd accumulation were observed among the different tissues. Increased Cd2+ level in the tissues also led to a significant increase in malonaldehyde (MDA) content, caused by increased lipid peroxidation. The activities of superoxide dismutase (SOD) and catalase (CAT) also increased, peaking at different Cd2+ concentrations, depending on the tissue. Glutathione peroxidases (GPx) activity in the gill and mantle initially increased, but then decreased with increasing external Cd2+ concentration. In the hepatopancreas and foot, GPx activity was inhibited by Cd2+, even at low concentrations. Furthermore, Cd2+ also stimulated the expression of MT in all ...