Abstract
Magnetic resonance imaging with high static magnetic fields (SMFs) has become widely used for medical imaging purposes because SMFs cause fewer genotoxic side effects than ionizing radiation (IR). However, the effect of exposure to high SMFs on global transcription is little understood. In this study, to elucidate the effects of SMFs or IR on individuals at the molecular level, we monitored the transcriptional alterations in C. elegans that were exposed to 3 or 5T SMF and 100Gy gamma-rays using the whole genome GeneChip array. In addition, we compared the effect of high SMFs with IR on genotoxicity, DNA double-strand break (DSB) formation and apoptosis in germline cells during gametogenesis. We demonstrate that genes involved in motor activity, actin binding, cell adhesion, cuticles and Ca2+ binding transiently and specifically induced following exposure to 3 or 5T SMFs. The small-heat shock protein gene hsp16 was also induced but to a much lesser extent, and the LacZ-stained population of hsp-16.1::lacZ transgenic worms did not significantly increase after exposure to SMFs with or without a second stressor, mild heat shock. Several genes encoding apoptotic cell-death activators and secreted surface proteins were upregulated after IR, but were not induced by SMFs. In addition, we constructed experimental systems using him-17 and abl-1 mutants to monitor genotoxicity of SMFs and IR. These results clearly indicate that exposure to high SMFs did not induce DSBs and induce apoptosis. Altogether suggests that the response of C. elegans to high SMFs is unique and capable of adjustment during long exposure, and that this treatment may be less hazardous than other therapeutic tools.
