Analysis of DNA damage structure after heavy ion radiation

Photon and particle irradiation causes different types of DNA damage. Photons, such as X- or γ-rays, induce DNA damage with a random distribution because of low-density energy deposition. In contrast, particle radiation with high linear energy transfer deposits high-density energy, resulting in the formation of clustered DNA damage containing DNA double- and single-strand breaks as well as base damage. To date, accumulated evidence has revealed that heavy-ion radiation results in dynamic chromosomal aberration, e.g., chromosomal translocations or large deletion mutations; however, the high incidence of these mutations after heavy-ion radiation cannot be simply explained by the formation of clustered DNA damage. Here we discuss the unique characteristics of DNA damage induced by heavy-ion radiation based on our recent findings using high-resolution imaging. (author)