Magnetic field exposure enhances DNA repair through the induction of DnaK/J synthesis

In contrast to the common impression that exposure to a magnetic field of low frequency causes mutations to organisms, we have demonstrated that a magnetic field can actually enhance the efficiency of DNA. repair, Using Escherichia coli strain XL-1 Blue as the host and plasmid pUC8 that had been mutagenized by hydroxylamine as the vector for assessment, we found that bacterial transformants that had been exposed to a magnetic field of 50 Hz gave lower percentages of white colonies as compared to transformants that had not been exposed to the magnetic field. This result was indicative that the efficiency of DNA repair had been improved. The improvement was found to he mediated by the induced overproduction of heat shock proteins DnaK/J (Hsp70/40). (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.