全氟辛酸暴露对蚯蚓DNA损伤和抗氧化酶基因表达水平的影响

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

笔者采用自然土壤培养法,通过28 d亚急性暴露实验,研究了全氟辛酸(perfluorooctanoic acid,PFOA)对赤子爱胜蚓(Eisenia foetida)的SOD,CAT,GST 3种抗氧化酶基因表达水平及DNA损伤的影响。研究结果表明:(1)PFOA胁迫可致蚯蚓体腔细胞DNA损伤,不同质量浓度的PFOA对蚯蚓体腔细胞尾长、尾部DNA含量和尾距均有明显的影响,且具有一定的剂量—效应关系,其中,尾矩和慧尾长度这2个指标对PFOA的胁迫最敏感。(2)PFOA胁迫也能引致蚯蚓抗氧化特异性基因表达水平的变化,CAT,GST,SOD 3种基因表达量变化趋势相似,质量浓度为1 mg·kg^(-1)时,蚯蚓SOD基因表达水平被诱导上调,质量浓度为5 mg·kg^(-1)和10 mg·kg^(-1)时,SOD表达量呈现剧烈下调的趋势;GST基因在10 mg·kg^(-1)组有明显下调,CAT基因表达在5 mg·kg^(-1)组基因表达水平最低,说明SOD基因的表达对PFOA的胁迫较敏感。蚯蚓体腔细胞DNA损伤和3种抗氧化酶基因表达水平的变化可作为潜在的生物标志物,用于监测PFOA对土壤生物蚯蚓的毒性大小。

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 of28 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^-1and 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^-1without 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.