菲和铬(Ⅵ)复合胁迫对蚯蚓抗氧化酶活性及其功能基因表达的影响

Antioxidant enzyme activity and gene expression of earthworms following combined exposure to phenanthrene and chromium(Ⅵ)

蚯蚓在土壤中大量存在,对土壤污染及带来的环境质量变化非常敏感。为评价多环芳烃菲和重金属铬(Ⅵ)复合胁迫对蚯蚓的分子毒理学效应,设置高(菲、铬(Ⅵ)分别为30.8、123.0mg/kg)、中(菲、铬(Ⅵ)分别为24.3、97.0mg/kg)、低(菲、铬(Ⅵ)分别为19.4、77.4mg/kg)3个复合胁迫浓度组,从超氧化物歧化酶(SOD)和过氧化氢酶(CAT)两种抗氧化酶活性和其功能基因(SOD和CAT基因)表达水平方面探索复合胁迫对蚯蚓酶活性及其功能基因表达的影响和相互关系。结果表明:菲和铬(Ⅵ)复合胁迫对蚯蚓体内SOD活性表现为先抑制再逐渐恢复,再转变为诱导作用,最大诱导率139.6%;对CAT活性表现为先抑制后诱导,最大诱导率179.5%。复合胁迫14d后,蚯蚓SOD和CAT基因均表现出上调作用,最大诱导效应出现在复合胁迫中浓度组的SOD基因,相对表达量是空白对照组的2.78倍。蚯蚓抗氧化酶活性与其功能基因之间总体表现出正相关性,功能基因也可作为一种重要的生物标志物。

Earthworms were abundant in the soil and very sensitive to soil pollution and environmental quality changes.To evaluate molecular toxicological effects of combined exposure to phenanthrene and chromium(Ⅵ)on earthworms,their antioxidant enzyme(superoxide dismutase,SOD;catalase,CAT)activities and the two target genes(SOD and CAT genes)were explored at three exposure levels which were 30.8 and 123.0 mg/kg,24.3 and 97.0 mg/kg,19.4 and 77.4 mg/kg for phenanthrene and chromium(Ⅵ),respectively,and the relationships among these biomarkers were further analyzed.Results demonstrated that SOD activities in earthworms were inhibited first,gradually recovered and then converted to induction with the maximum rate of 139.6%;CAT activities in earthworms were inhibited first and then induced with the maximum rate of 179.5%.Compared to the control,the up\|regulation trend of expression levels of the two genes could be clearly observed after 14 days incubation,the maximum being 2.78 times for SOD gene of earthworms exposed to combined treatments at the medium concentration.In general,there existed positive correlations between target genes expression levels and antioxidant enzyme activities,indicating that genes expression could serve as one kind of biomarkers.