Mitotic recombination induced by chemical and physical agents in the yeast Saccharomyces cerevisiae |
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Authors: | P.J. Davies W.E. Evans James M. Parry |
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Affiliation: | Department of Genetics, University College of Swansea Swansea, SA 2 8 PP, Great Britain |
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Abstract: | The treatment of diploid cultures of yeast with ultraviolet light (UV), γ-rays, nitrous acid (NA) and ethyl methane sulphonate (EMS) results in increases in cell death, mitotic gene conversion and crossing-over. Acridine orange (AO) treatment, in contrast, was effective only in increasing the frequency of gene conversion. The individual mutagens were effective in the order UV > NA > γ-rays > AO > EMS. Prior treatment of yeast cultures in starvation medium produced a significant reduction in the yield of induced gene conversion.The results have been interpreted on the basis of a general model of mitotic gene conversion which involves the post-replication repair of induced lesions involving de novo DNA synthesis without genetic exchange. In contrast mitotic crossing-over appears to involve the action of a repair system independent from excision or post-replication repair which involves genetic exchange between homologous chromosomes. |
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Keywords: | AO acridine orange EMS ethyl methynesulphonate NA nitrous acid |
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