14.6 mT ELF magnetic field exposure yields no DNA breaks in model systemSalmonella, but provides evidence of heat stress protection

Abstract

In this study, we demonstrate that common extremely low frequency magnetic field (MF) exposure does not cause DNA breaks in this Salmonella test system. The data does, however, provide evidence that MF exposure induces protection from heat stress. Bacterial cultures were exposed to MF (14.6 mT 60 Hz field, cycled 5 min on, 10 min off for 4 h) and a temperature-matched control. Double- and single-stranded DNA breaks were assayed using a recombination event counter. After MF or control exposure they were grown on indicator plates from which recombination events can be quantified and the frequency of DNA strand breaks deduced. The effect of MF was also monitored using a recombination-deficient mutant (recA). The results showed no significant increase in recombination events and strand breaks due to MF. Evidence of heat stress protection was determined using a cell viability assay that compared the survival rates of MF exposed and control cells after the administration of a 10 min 53 degrees C heat stress. The control cells exhibited nine times more cell mortality than the MF exposed cells. This Salmonella system provides many mutants and genetic tools for further investigation of this phenomenon.

Effect of 2.45 mT sinusoidal 50 Hz magnetic field onSaccharomyces cerevisiaestrains deficient in DNA strand breaks repair

“…Luceri et al (2005) reported that extremely-low frequency MF (1, 10 and 100 mT, 50 Hz, 18 h) do not induce DNA damage or affect gene expression in S. cerevisiae. Williams et al (2006) observed that 60 Hz, 14.6 mT MF cycled (5 min on, 10 min off; 4 h) does not cause DNA breaks. They used the model organism Salmonella enterica defectives in the recA recombination repair mechanism, required to repair single or double DNA strand breaks in the strains used by these authors.…”

“…Genotoxic effects of EMF may occur directly by damage to DNA and DNA repair mechanisms (Ivancsits et al 2002). Controversial results, about the induction of DNA strand breaks or the completely absence of such effects, have been published at different EMF intensity levels (Ivancsits et al 2003, Lai and Singh 2004, Scarfi et al 2005, McNamee et al 2005, Wolf et al 2005, Villarini et al 2006, Williams et al 2006, Ruiz-Gó mez and Martínez-Morillo 2009). The primary MF interaction mechanisms may to involve the Radical Pair Mechanism (RPM) in which low level MF drive pairs of radicals from the singlet to the triplet spin state.…”

Сhiral and Racemic Fields Concept for Understanding of the Homochirality Origin, Asymmetric Catalysis, Chiral Superstructure Formation from Achiral Molecules, and B-Z DNA Conformational Transition

“…However, since the pulsed magnetic field is not found in nature, DNA has no protective mechanism from it. Probably, that is why the static magnetic field has little effect on DNA and the cell in vivo whereas the pulsated magnetic field affects DNA and the cell radically [320][321][322]330]. According to the same logic we can suggest that periodic long-term gravitational pulsations (lunar tides), as a common phenomenon on Earth, have a protective mechanism against DNA damage (corresponding DNA repair mechanism) whereas static gravitation is uncommon for living organisms on Earth.…”

“…Therefore, usually, a low frequency electromagnetic or a low frequency magnetic field (alone or in combination with other factors) can affect DNA; however, some scientists disagree with this opinion [322,323].…”

Extremely low frequency magnetic field exposure affects DnaK and GroEL expression in E. coli cells with impaired heat shock response

“…Many studies on extremely low frequency (ELF)-MF have showed that exposure to these fields can affect biological functions such as RNA transcription, cell viability, cell proliferation although it is unknown which molecular mechanisms are involved (Babincova et al 2000;Ventura et al 2005;Williams et al 2006;Kroupova et al 2007;Novak et al 2007;Cellini et al 2008). Still it is not still clear whether ELF-MF exposure can represent a stress factor for the cells.…”