OXIDATIVE MUTAGENS INDUCE INTRACHROMOSOMAL RECOMBINATION IN YEAST

Active oxygen species are thought to be involved in the causation of a number of diseases including cancers. We have investigated the effect of 5 oxidative mutagens, methyl viologen (paraquat), mitomycin C, phe nylhydrazine, cumene hydroperoxide and hydrogen peroxide, on the frequ ency of both intrachromosomal recombination and interchromosomal recom bination in the yeast Saccharomyces cerevisiae. All of the chemicals s ignificantly increased the frequency of intrachromosomal recombination in a dose-dependent manner. Only hydrogen peroxide increased the freq uency of interchromosomal recombination at the doses tested in this st udy. A role for hydroxyl radical (OH) in the effect of H2O2 on recombi nation is indicated by the ability of the radical scavenger dimethyl s ulfoxide (DMSO) to significantly inhibit the induction of both intrach romosomal and interchromosomal recombination by H2O2. The results pres ented here give further support for the suitability of intrachromosoma l recombination measurements as a short-term test for the detection of mutagens and carcinogens.