用彗星试验检测土壤污染对蚯蚓活体基因损伤

彗星试验,又称单细胞凝胶电泳,因其能够在单细胞水平上灵敏地检验DNA链断裂,成为研究遗传毒性效应的新技术,近年来得到重要应用。比较而言,如何利用该技术来检验土壤无脊椎动物活体基因损伤的报道则很少。本研究以丝裂霉素C(MitomycinC)为遗传毒性阳性物质,研究了用彗星试验检验赤子爱胜蚓(Eiseniafoetida)活体基因损伤的实验方法,对尾长、“彗尾”DNA含量和尾矩三个指标定量表达实验结果的敏感性进行讨论,并以污水灌溉土壤样品为例研究了污染土壤导致的蚯蚓体内DNA单链断裂。结果表明,采用彗星试验检测蚯蚓体内DNA单链断裂的基因损伤效应可以作为生物效应标志终点,尾矩和尾长作为敏感指标可以更好地表达遗传毒性物质基因损伤的剂量-效应关系。

DETECTION OF GENOTOXICITY OF SOIL POLLUTION TO EARTHWORM INVIVO EXPOSURE BY COMET ASSAY

The comet assay (the alkaline single cell gel electrophoresis) was applied universally in the field of ecotoxicology as a sensitive bioassay to detect DNA damage in the cell level.Little has been reported on its application in assessing effects of mutagens on earthworms in the soil ecosystem.In this paper,earthworms (Eisenia foetida) were exposed to different levels of mitomycin C and soil samples collected from an area irrigated with wastewater for years.After the exposure,coelomecytes of the earthworms were extracted and subjected to comet assay.The samples were compared in endpoints,such as tail length (TL),tail DNA content (TD) and tail moment (TM).Results show that the utilization of comet assay in combination with vivo exposure of earthworms is a promising tool for evaluation of mutagenic chemicals and polluted soil,and that among the endpoints,TM and TL are more sensitive in representing the dose-effect relationship.