Effect of power-frequency magnetic fields on genome-scale gene expression in Saccharomyces cerevisiae

To estimate the effect of 50 Hz magnetic-field exposure on genome-wide gene expression, the yeast Saccharomyces cerevisiae was used as a model for eukaryotes. 2D PAGE (about 1,000 spots) for protein and cDNA microarray (about 5,900 genes) analysis for mRNA were performed. The cells were exposed to 50 Hz vertical magnetic fields at 10, 150 or 300 mT r.m.s. for 24 h. As positive controls, the cells were exposed to aerobic conditions, heat (40 degrees C) or minimal medium. The 2D PAGE and microarray analyses for the positive controls showed high-confidence differential expression of many genes including those for known or unknown proteins and mRNAs. For magnetic-field exposure, no high-confidence changes in expression were observed for proteins or genes that were related to heat-shock response, DNA repair, respiration, protein synthesis and the cell cycle. Principal component analysis showed no statistically significant difference in principal components, with only insignificant differences between the magnetic-field intensities studied. In contrast, the principal components for the positive controls were significantly different. The results indicate that a 50 Hz magnetic field below 300 mT did not act as a general stress factor like heat shock or DNA damage, as had been reported previously by others. This study failed to find a plausible differential gene expression that would point to a possible mechanism of an effect of magnetic fields. The findings provide no evidence that the magnetic-field exposure alters the fundamental mechanism of translation and transcription in eukaryotic cells.