The effect of low frequency electric and magnetic fields on gene expression in Saccharomyces cerevisiae

Differential effects of extremely low frequency (e.l.f.) electromagnetic (EM) field exposure on several genes in yeast cells are reported. Transcript levels for the genes URA3, IME2 and SSA1 in Saccharomyces cerevisiae were measured following exposures to a 60 Hz continuous wave sinusoidal field at various field strengths and exposure times. An increase in the basal level of URA3 transcripts was observed as a function of field strength and time of exposure, i.e. a peak in transcript levels for URA3 was observed after 15 min exposure at the lowest field strength used in these experiments (0.8 μT). With increased field strengths (8 and 80 μT) the peak effect was delayed and transcript levels were somewhat lower. With continuous exposure, transcript levels decreased to control levels within 60 min regardless of the field strength used. Transcript levels in cells exposed for 20 min and removed from the field returned to control levels within 20 min. Re-exposure for up to 40 min after a 20 min initial exposure did not alter transcript levels from control levels. IME2, a meiotic regulatory gene, was unaffected by exposure to any of the field strengths used in these experiments. Although these two genes responded differently to the EM fields at 30°C, transcript levels for both URA3 and IME2 were increased in yeast cells subjected to sudden elevated temperature (37°C) for 20 min. Transcript levels for SSA1 (a heat shock gene) were increased in yeast cells exposed to either electromagnetic fields or sudden elevated temperature.