Abstract
To elucidate the mechanism of low dose rate radiation-induced carcinogenesis, it is important to analyze spontaneous mutation frequencies at various tissues with aging and tissue specific mutation rates induced by radiation. Real time PCR method was used to observe four types deletion mutation of mitochondrial DNA from liver and brain in mice irradiated by γ-ray with 0.6Gy/min. Accumulations of four types of mtDNA deletions were observed with aging in all tissues. In contrast these deletion mutations in mitochondria were not induced by 7.5Gy of radiation. These findings suggest that the quantity of ROS (reactive oxygen species) in mitochondria produced by radiation may be within the limits which can remove with defense mechanism in the living cell. This work was supported by Aomori Prefecture, Japan. [J Radiat Res 44:403 (2003)]
