Department of Genetics, Microbiology and Toxicology, Stockholm University, S-106 91 Stockholm, Sweden.
Mutat Res. 2011 May 18;722(1):84-8. doi: 10.1016/j.mrgentox.2011.03.011. Epub 2011 Mar 29.
Extremely low frequency (ELF) magnetic fields have previously been shown to affect conformation of chromatin and cell proliferation. Possible genotoxic and carcinogenic effects of ELF have also been discussed and tested. In this study, we analyzed the effect of ELF on chromatin conformation in E. coli GE499 cells by the anomalous viscosity time dependence (AVTD) technique. Possible genotoxic ELF effects at the specific combination of static and ELF magnetic fields, that has been proven to have effects on chromatin conformation, were investigated by clonogenic assay, cell growth kinetics, and analysis of SOS-response using inducible recA-lacZ fusion and the β-galactosidase assay. Genotoxic agent nalidixic acid (NAL) was used as positive control and in combination with ELF. Nalidixic acid at 3-30μg/ml decreased the AVTD peaks and induced cytotoxic effect. In contrast to NAL, ELF increased AVTD, stimulated cell growth, and increased cloning efficiency. These effects depended on frequency within the frequency range of 7-11Hz. While NAL induced SOS response, ELF exposure did not induce the recA-lacZ fusion. Exposure to ELF did not modify the genotoxic effects of NAL either. All together, the data show that ELF, under specific conditions of exposure, acted as nontoxic but cell growth stimulating agent.
极低频（ELF）磁场先前已被证明会影响染色质构象和细胞增殖。ELF 的可能遗传毒性和致癌作用也已被讨论和测试。在这项研究中，我们通过异常粘度时间依赖性（AVTD）技术分析了 ELF 对 E. coli GE499 细胞染色质构象的影响。通过集落形成测定、细胞生长动力学和诱导型 recA-lacZ 融合的 SOS 反应分析以及β-半乳糖苷酶测定，研究了在已被证明对染色质构象有影响的静态和 ELF 磁场的特定组合下，ELF 对遗传毒性的可能影响。遗传毒性剂萘啶酸（NAL）被用作阳性对照并与 ELF 联合使用。3-30μg/ml 的萘啶酸降低了 AVTD 峰并诱导细胞毒性。与 NAL 相反，ELF 增加了 AVTD、刺激了细胞生长并提高了克隆效率。这些效应取决于频率，频率范围为 7-11Hz。虽然 NAL 诱导了 SOS 反应，但 ELF 暴露并未诱导 recA-lacZ 融合。ELF 暴露也没有改变 NAL 的遗传毒性作用。总的来说，这些数据表明，在特定的暴露条件下，ELF 作为一种无毒但刺激细胞生长的物质发挥作用。
