赤子爱胜蚓对氯氰菊酯暴露的生态毒性响应

Ecotoxic Responses of Earthworm Eisenia fetida Exposed to Cypermethrin

以赤子爱胜蚓为供试生物,采用滤纸接触法及土壤培养法,通过急性毒性、生长毒性、再生繁殖毒性试验及CYP3A4酶活性毒性响应试验,进行了在不同生态响应水平上氯氰菊酯胁迫对蚯蚓的毒性效应研究,初步确定了急性毒性、生长繁殖和细胞酶活力指标的敏感性。结果表明:滤纸试验中氯氰菊酯对蚯蚓的48h LC50和72h LC50分别为445.4、212.1μg·cm-2,土壤试验中7d LC50和14d LC50分别为121.6、80.2 mg.kg-1;再生繁殖试验中低剂量氯氰菊酯刺激蚯蚓体重增长、短期内诱导蚯蚓产茧率,抑制蚯蚓幼体孵育。CYP3A4酶活性毒性响应滤纸试验中氯氰菊酯对蚯蚓的CYP3A4酶活性产生明显诱导的浓度为21.5ng·cm-2,在214.8ng·cm-2产生明显的抑制作用;土壤试验中3d暴露后,10mg.kg-1氯氰菊酯诱导蚯蚓体内CYP3A4活性显著升高,随着暴露时间延长,氯氰菊酯对CYP3A4活性的诱导作用始终存在,但诱导的高值浓度随暴露时间的延长而降低,CYP3A4酶活力与土壤中氯氰菊酯浓度之间呈现明显的倒U型量-效响应曲线。研究表明,各指标敏感性表现为细胞酶活力>生长繁殖>急性毒性,同时也证明了CYP3A4可以作为土壤拟除虫菊酯风险评价的潜在敏感生物标记物。

Pyrethroid is widely used around the world, and contributed greatly to the agricultural development. But a large portion of pyrethroid used in agriculture ends up as residuals in the soil, making soildwelling organisms more vulnerable to pesticide intoxication. Earthworm is one of the most common soil oragnisms in most environments, and plays an important role in the functioning of soil ecosystems. The analyzing of P450 enzyme activity in earthworm is a newly developed practice for soil pollution risk assessment. The toxicology of cyper-methrin on the earthworm Eisenia fetida was evaluated by measurements of the acute response, growth, reproduction and CYP3A4 activity of the earthworm incubated on filter paper and in soil. The acute response test showed that 48 h-LC 50 and 72 h-LC 50 by the filter paper contacting method were 445.5 μg·cm -2 and 212.1 μg·cm -2 , respectively, and 7 d-LC 50 and 14 d-LC 50 by the soil incubation method were 121.6 mg· kg -1 and 80.2 mg·kg -1 , respectively. A low dose of cypermethrin induced the growth of the earthworm and the cocoon production in short time but restrained the incubation of juveniles. The CYP3A4 activity of the earthworm on filter paper was induced by cypermethrin at 21.5 ng·cm -2 and inhibited at 214.8 ng·cm -2 . A 3-day exposure of cypermethrin at 10 mg·kg -1 significantly induced the CYP3A4 activity of the earthworm in the soil, and the inducting effect remained but tended to be weaker with the prolonging of the exposure time. The low toxicity of cyperme-thrin on the earthworm was revealed by the LC 50 , growth rate and cocoon production rate, with the sensitivity being in an order of enzymatic activity>growth and reproduction indicator>acute toxicity. However, the significant inverse U type dose-response relationship observed between the CYP3A4 activity and the concentration of cypermethrin reflected its endocrine disruption effect on the earthworm. This experiment also demonstrated CYP3A4 could be used as a potential biomarker to assess the ecological risk of pyrethroid pollution in soil.