Antioxidant and metabolic responses induced by cadmium and pyrene in the earthworm Eisenia fetida in two different systems: contact and soil tests

Abstract

The effects of cadmium and the polycyclic aromatic hydrocarbon (PAH) pyrene on the earthworm Eisenia fetida were investigated in contact and soil tests. Metabolic (glutathione-S-transferase, GST) and oxidative (catalase, CAT) stress enzymes were studied as biomarkers in earthworms after 48 hours, 14 days and 28 days. Contact test indicated that cadmium had significant effects on survival and enzyme activities while pyrene influenced neither in the studied concentrations. Induction of CAT and GST in earthworms exposed to cadmium and pyrene in the acute soil test (14 d) revealed the metabolism of these chemicals resulting in the production of reactive oxygen species. After a relatively long period of exposure (28 d), earthworms exposed to pyrene failed to handle the high toxicity and were physiologically damaged, while those exposed to cadmium adapted to the disturbed environment through effective metabolism of the chemical and management of the oxidative stress.

Keywords:

• cadmium
• pyrene
• glutathione-S-transferase (GST)
• catalase (CAT)
• earthworm (Eisenia fetida)
• contact test
• soil test
• acute and chronic exposure
• OECD soil

Acknowledgements

This work was supported by the National Basic Research Program (Grant No. 2007CB407307), National Natural Science Foundation of China (No. 40601089) and the Knowledge Innovation Program of the Chinese Academy of Sciences (grant No. KZCX2-YW-420-5 and KZCX1-YW-06-05). We are also grateful to Rixiang Huang and Shuang Gao for their assistance in the experimental procedures.