蚯蚓细胞色素P450酶系对土壤中芘或苯并[a]芘的响应

Responses of cytochrome P450s family of earthworms exposed to individual pyrene or benzo [a] pyrene-contaminated soil

以赤子爱胜蚓(Eisenia fetida)为受试生物,通过人工污染草甸棕壤微宇宙试验方法,研究了暴露于不同环境浓度芘或苯并[a]芘(添加量分别为0.12、0.24、0.48、0.96 mg·kg^(-1))污染的土壤中14 d后,蚯蚓体内细胞色素P450(CYPs)酶系,如CYPs总量、CYP1A1及CYP2C9活性的变化.结果显示,芘或苯并[a]芘暴露导致蚯蚓CYPs总量、CYP1A1及CYP2C9活性的变化不同.其中,CYPs总量与CYP1A1活性对芘的响应趋势相似:试验3 d后,0.96 mg·kg^(-1)芘导致二者都显著高于对照水平;14 d后,都显著低于对照水平;CYP1A1活性对芘的响应更为敏感.CYPs总量与CYP2C9活性对苯并[a]芘的响应趋势相似:暴露初期,苯并[a]芘最高暴露剂量(0.96 mg·kg^(-1))导致二者都显著低于对照水平;试验结束后,苯并[a]芘最低暴露剂量(0.12 mg·kg^(-1))导致二者都显著高于对照水平,最高剂量暴露导致二者都显著低于对照水平,CYP2C9活性对苯并[a]芘的响应更为敏感.因此,推断CYPs亚酶对污染物的响应具有选择性且亚酶的响应敏感度高于CYPs总量.将CYPs总量与CYP1A1活性结合,或与CYP2C9活性结合分别诊断土壤芘污染或并[a]芘污染,较为准确有效.

As a test organism,earthworms（ Eisenia fetida） were exposed to different doses（ 0.12,0.24,0.48 and 0.96 mg·kg^-1） of individual pyrene or benzo[a]pyrene（ B[a]P） for 14 d in spiked contaminated medaow brown soil.On the 3rd,7thand 14 thday,cyptochrome P450s（ CYPs） total content and CYP1A1 and CYP2C9 activities of earthworms were determined.The results indicated that the responses of CYPs total content and CYP1A1 and CYP2C9 activities were greatly different from each other when exposed to pyrene or benzo[a]pyrene.It was found that the response trends of CYPs total content and CYP1A1 activity of earthworms were similar in pyrene exposure,and were significantly higher on the 3rdday and obviously lower on the 14 thday than those in the control.In addition,compared with CYPs total content and CYP2C9 activity,CYP1A1 activity responded more sensitively to pyrene. For B[a]Pexposure,response trends of CYPs total content and CYP2C9 activity of earthworms were similar.The highest dose resulted in significant inhibition on the3 rdday.While on the 14 thday,the highest dose resulted in obvious decrease and the lowest dose caused their great enhancement compared to the control group.Moreover,our results showed CYP2C9 activity responded to B[a]P more sensitively than CYPs total content and CYP1A1 activity. Therefore,we conclude that the responses of CYPs isoforms to soil contaminants are selective and more sensitive than CYPs total content. CYPs total content combined with the isoforms is more accurate and effective for diagnosing soil pollution,i.e.with CYP1A1 for the diagnosis of soil pyrene pollution and with CYP2C9 for B[a]P pollution.