Biological responses to static high magnetic fields in C. elegans.

In recent years, the biological effects of extremely-low-frequency magnetic fields (ELF MFs) on possible health hazards have been reported. In rat brain cells, 0.25-0.5 mT of 60Hz ELF MF introduces DNA double-strand (ds) breaks. On the other, it is known that static high magnetic fields (st MFs) are much more safety and used for MRI. But, biological responses at the molecular level to the st MFs are little understood. Thus, we study the influences of the st MFs on growth, development, reproduction, ds breaks, apoptosis, and alterations of entire gene expression using a model metazoan C. elegans. Under 5T st MF, the growth, development and reproduction normally proceeded. In order to study whether the ds breaks were introduced by the static MFs, we used him-17 mutant, whose activity of meiotic ds breaks for general recombination was reduced, and measured hatching rate of the eggs and incidence of males (XO animals). Both the frequencies were not significantly changed under 2T and 3T st MFs compared with 0T control. In addition, we analyzed alterations of entire gene expression using DNA microarray under 3T and 5T st MFs. The alteration patterns between the cases of exposure of st MFs and gamma rays irradiation were quite different. Those results indicate st MFs did not introduce any DNA damage. We also found that hsp-16 gene expression increased under the st MFs as well as the ELF MFs reported, indicating that hsp-16 gene was response to several MFs. In this presentation, we would like to discuss the biological responses to st MFs including other altered gene expression.