The Effect of PFOA Exposure on DNA Damage and Gene Expression Levels of Antioxidant Enzyme of Eisenia foetida

Key words: 
• perfluorooctanoic acid（PFOA） /
• Eisenia foetida /
• DNA damage /
• antioxidant enzyme /
• gene expression

Abstract: Perfluorooctanoic acid（ PFOA）,a kind of synthetic chemicals,widely exists in the environment. It can be accumulated in higher animals because of its good chemical stability and thermal stability,which makes it become a persistent organic matter of concern in the environment. Earthworms of Eisenia foetida,an indicating animal,were exposed to PFOA at different exposure concentrations to assay their DNA damage and the gene expression of their antioxidant enzymes,SOD,CAT and GST,by using natural soil contact method with a cycle of 28 days. PFOA stress resulted in DNA damage of the coelomic cells of the earthworm. PFOA exhibited significant effect on the tail length（ TL）,tail moment（ TM） and tail DNA content（ TD）（ P ＜ 0. 05） of the earthworms at different exposure concentrations with a given dose-response relationship（ P ＜ 0. 01）,and the TL and TM were two indicators that were most sensitive to PFOA exposure. PFOA stress also induced the change of antioxidant-specific gene expression of the earthworms. SOD gene expression was induced to show upregulation in response to the PFOA at the concentration of 1 mg·kg^-1,and then significant down-regulation at the concentration of 5mg·kg^-1 and 10mg·kg^-1. GST gene expression was obviously down-regulated at the PFOA concentration of 10mg·kg^-1. The expression level of CAT gene was lowest at the PFOA concentration of 5 mg·kg^-1 without significant difference compared with the control. Of the genes of the antioxidant enzymes in the earthworm the SOD gene was found the most sensitive to PFOA. All these results showed that the DNA damage of earthworm coelomic cells and the change of gene expression of antioxidant enzymes of the earthworm could be used as biomarkers to indicate the effect of PFOA on the earthworm,a soil organism.