Effect of caffeine on the rho- -induction with ethidium bromide in Saccharomyces cerevisiae

It is shown that caffeine antagonizes petite-induction with ethidium bromide under non-growth conditions when administered during or after mutagenic treatment. Caffeine itself is shown to be a petite-inducing agent when cells are grown in liquid glucose-complete-medium in the presence of the drug. A possible mode of action of caffeine in the ethidium bromide induced petite-mutagenesis is discussed.