EFFECT OF MILLIMETER WAVES ON UV-INDUCED RECOMBINATION AND MUTAGENESIS IN YEAST

Effects of millimeter waves (MMW) on cell survival and ultraviolet-ind uced reciprocal and non-reciprocal recombination and mutagenesis were studied in the diploid D7 strain of the yeast Saccharomyces cerevisiae . MMW exposures lasted for 30 min (0.13 mW cm(-2), 61.02-61.42 GHz) an d were followed in 60 min by a 100 J m(-2) dose of 254 nm ultraviolet (UV) radiation. The effect of the exposures was evaluated from the col ony-forming ability of the cells on complete and selective media, and from the number of aberrant colonies formed. The MMW pretreatment did not alter cell survival or the frequency of reverse mutations. The inc idence of conversions was higher in most cases in the MMW-treated cell s (p < 0.05). MMW also increased the scores of crossovers and colored aberrants in isolated experiments, though the average increase for all experiments (performed with different MMW frequencies) was not statis tically significant. The results suggested that the MMW irradiation di d not alter the UV-induced mutagenesis, but could facilitate recombina genic processes. (C) 1997 Elsevier Science S.A.