Griffin D E, Hill W E
Mutat Res. 1978 Nov;52(2):161-9. doi: 10.1016/0027-5107(78)90138-0.
Covalently closed circular molecules of the colicinogenic plasmid E1 can serve as sensitive indicators for detecting in vitro breakage of DNA. After these molecules are radioactively labeled and purified by cesium chloride density-gradient centrifugation, they are incubated with the compounds to be tested. Samples are analyzed on alkaline sucrose gradients to determine the fraction of unbroken molecules and a breakage rate is calculated. Positive results were obtained for all three mutagenic alkylating agents (MMS, EMS, and MNNG) and of the 11 pesticides tested, dexon, dichlorvos, malathion, and methyl parathion induced breaks in molecules at a rate significantly greater than the controls.
产大肠杆菌素质粒E1的共价闭合环状分子可作为检测DNA体外断裂的敏感指标。这些分子经放射性标记并用氯化铯密度梯度离心法纯化后，与待测化合物一起孵育。在碱性蔗糖梯度上分析样品，以确定未断裂分子的比例，并计算断裂率。三种诱变烷基化剂（甲磺酸甲酯、甲基磺酸乙酯和N-甲基-N'-亚硝基胍）以及所测试的11种农药中的敌克松、敌敌畏、马拉硫磷和甲基对硫磷均得到了阳性结果，它们使分子断裂的速率显著高于对照组。
