| Literature DB >> 15645314 |
B Del Re1, F Bersani, C Agostini, P Mesirca, G Giorgi.
Abstract
Previous assays with weak sinusoidal magnetic fields (SMF) have shown that bacteria that had been exposed to a 50 Hz magnetic field (0.1-1 mT) gave colonies with significantly lower transposition activity as compared to sham-exposed bacteria. These experiments have now been extended by using a pulsed-square wave magnetic field (PMF) and, unexpectedly, it was found that bacteria exposed to PMF showed a higher transposition activity compared to the controls. The increase of the transposition activity was positively correlated with the intensity of the magnetic fields (linear dose-effect relation). This phenomenon was not affected by any bacterial cell proliferation, since no significant difference was observed in number and size of PMF-exposed and sham-exposed colonies. In addition, the cell viability of E. coli was significantly higher than that of the controls when exposed to SMF, and lower than that of the controls when exposed to PMF. Under our experimental conditions it was shown that exposure to PMF stimulates the transposition activity and reduces cell viability of bacteria, whereas exposure to SMF reduces the transposition mobility and enhances cell viability. These results suggest that the biological effects of magnetic fields may critically depend on the physical characteristics of the magnetic signal, in particular the wave shape.Entities:
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Year: 2004 PMID： 15645314 DOI： 10.1007/s00411-004-0260-9
Source DB: PubMed Journal: Radiat Environ Biophys ISSN： 0301-634X Impact factor: 1.925