title: Toxicity and SOS-response to ELF magnetic fields and nalidixic acid in E. coli cells.
abstract: Extremely low-frequency magnetic fields (ELF-MF) have previously been shown to affect conformation of chromatin and cell proliferation. Possible genotoxic and carcinogenic effects of ELF-MF have also been discussed and tested. In this study, we analysed the effect of ELF-MF on chromatin conformation in E. coli GE499 cells by the anomalous viscosity time-dependence (AVTD) technique. Possible genotoxic effects of the specific combination of static and ELF-MF, which has been proven to affect chromatin conformation, were investigated by a clonogenic assay, by assessing cell-growth kinetics, and by analysis of the SOS-response by means of inducible recA-lacZ fusion-gene products and the β-galactosidase assay. The genotoxic agent nalidixic acid (NAL) was used as a positive control and in combination with ELF-MF. Nalidixic acid at 3-30μg/ml decreased the AVTD peaks and induced a cytotoxic effect. In contrast to NAL, ELF-MF fields increased AVTD, stimulated cell growth, and increased cloning efficiency. These effects depended on the frequency within the range of 7-11Hz. While NAL induced an SOS-response, exposure to ELF-MF did not induce the recA-lacZ fusion-gene product. Exposure to ELF-MF did not modify the genotoxic effects of NAL either. All together, the data show that ELF-MF, under specific conditions of exposure, acted as a non-toxic but cell-growth stimulating agent.
authors.affiliation: Laboratory of Molecular Genetics, Cancer Research Institute, Bratislava, Slovak Republic. Igor.Belyaev@savba.sk
authors.forename: Igor
authors.initials: I
authors.lastname: Belyaev
mesh_terms: D049109:Cell Proliferation; D002843:Chromatin / Q000737:chemistry*; D004249:DNA Damage; D004574:Electromagnetic Fields; D004926:Escherichia coli / Q000235:genetics; D008968:Molecular Conformation; D009268:Nalidixic Acid / Q000494:pharmacology*; D013014:SOS Response, Genetics
chemical_list: D002843:Chromatin; D009268:Nalidixic Acid