In vitro breakage of plasmid DNA by mutagens and pesticides. |
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Authors: | D E Griffin W E Hill |
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Institution: | Department of Microbiology, University of Southwestern Louisiana, Lafayette, LA 70504 U.S.A. |
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Abstract: | 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. |
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Keywords: | ColE1 colicinogenic plasmid E1 DDT Dichloro-diphenyl-trichloroethane DMSO dimethyl sulfoxide DNA deoxyribonucleic acid EMS ethyl methanesulfonate MMS methyl methanesulfonate MNNG UDS unscheduled DNA synthesis |
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