Effect of cadmium on the antioxidant system of the ascidian, Styela clava

Abstract

The metal accumulations and the corresponding enzymatic responses in the ascidian Styela clava (Herdman 1881) were investigated. S. clava were exposed to sublethal concentrations of cadmium (0.01, 0.05, 0.1 or 0.2 mg Cd l⁻¹) for 40 days. The biochemical stress response of S. clava was studied taking into account superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), as well as lipid peroxidation (LPO) and total oxyradical scavenging capacity (TOSC). The present study confirms the presence of antioxidant enzymatic activity in the tissues of S. clava, reflecting a physiological adaptation to continuous metal exposure in their natural environment. Cd exposure induced a significant TOSC, SOD (cytosolic and mitochondrial), CAT and GPx activity promotion in ascidians. After several days of exposure, the decreased enzymatic activities during continuous Cd treatment may be a contributing factor for the observed increased level of oxyradicals and lower TOSC. Under high rates of input of free radicals, enzyme inactivation prevails and the enzymatic activities are reduced leading to autocatalysis of oxidative damage processes.

Keywords:

• Antioxidant enzyme
• ascidians
• cadmium
• lipid peroxidation
• Styela clava
• total oxyradical scavenging capacity

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

The authors are grateful to the National Nature Science Foundation of China for financial support (No. 31070368). Thanks are also due to Mr Guo for his assistance during the experiments.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark