Abstract
It is known that DNA lesions induced by ionizing radiation and chemicals can cause mutation and carcinogenesis. In particular, "clustered damage" site, that is a DNA region with multiple lesions within a few helical turns, is believed to hardly be repaired. This type of damage is considered to be induced around high-LET radiation tracks and at track-end of secondary electron. However, details of the clustered damage sites are not known. In order to get experimental information about the hypothetical damage, we have developed an analytical method for measuring the degree of dispersion of distances between DNA lesions using Förster resonance energy transfer (FRET). Experimentally-obtained FRET efficiencies of random distributed AP-sites on heat-treated DNA almost correspond to theoretical ones calculated on the basis of exponential distribution. Now we have tried to apply the FRET methodology to plasmid DNA irradiated with some radiation qualities. The results and the perspective will be discussed.
