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

全氟辛酸(perfluorooctanoic acid,PFOA)是环境中存在的最典型的全氟化合物之一,能在高等动物体内蓄积,成为备受关注的持久性有机物。采用自然土壤培养法,通过28d亚急性暴露实验,研究了PFOA对赤子爱胜蚓(Eisenia foetida)的SOD、CAT、GST三种抗氧化酶基因表达水平及DNA损伤的影响。研究结果表明：PFOA胁迫可致蚯蚓体腔细胞DNA损伤,不同浓度的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两个指标对PFOA的胁迫最为敏感。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和SOD三种基因表达量变化趋势相似,在浓度为1mg/kg时蚯蚓SOD基因表达水平被诱导上调,浓度为5mg/kg和10mg/kgSOD表达量呈现剧烈下调的趋势,GST基因在10 mg/kg浓度组有明显下调,CAT基因表达在5 mg/kg 浓度组基因表达水平最低,SOD基因的表达对PFOA的胁迫较为敏感。蚯蚓体腔细胞DNA损伤和三种抗氧化酶基因表达水平的变化可以作为潜在的生物标志物,以监测PFOA 对土壤生物蚯蚓毒性作用。

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

Perfluorooctanoic acid (PFOA) is a kind of synthetic chemicals and 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. The effect of PFOA at different exposure concentration on DNA damage and gene expression of antioxidant enzyme to Eisenia foetida was studied by using natural soil contact method with a cycle of 28d. Tail length(TL) , tail moment(TM),tail DNA content(TD)values not only exhibited a significant difference(P<0.05)compared with the control, but also has a strong dose-response relationship(P<0.01). SOD gene expressions was induced in response to concentration of 1mg/kg,then it was significantly down-regulated at the concentration of 5mg/kg and 10mg/kg compared to the controls.GST gene expression showed the same trend at at concentration of 5mg/kg as Sod gene.The expression level of CAT gene was lowest at the concentration of 5mg/kg without significant difference compared with control group.The gene of SOD was the most sensitive on the exposure of PFOA. The results showed that DNA damage and the changing of gene express of antioxidant enzymes of earthworm could be as a biomarker to indicate the effect of PFOA on soil organisms.