Detection of DNA damage induced by heavy ion irradiation in the individual cells with comet assay

Wada, Seiichi; Natsuhori, Masahiro*; Ito, Nobuhiko*; Funayama, Tomoo; Kobayashi, Yasuhiko

Determining the biological effects of a very low number of charged particles crossing the cell nucleus is interest for estimating the risk due to environmental exposure to charged particles. Especially it is necessary to detect the radiation damage induced by a precise number of charged particles in the individual cells. To compare the number of ions traversing the cell and the DNA damage produced by the hit ions, we applied comet assay. Cells attached on the ion track detector CR-39 were irradiated with 17.3 MeV/u 12C, 15.7 MeV/u, 10.4 MeV/u 20Ne and 6.9 MeV/u 40Ar ion beams at TIARA, JAERI-Takasaki. After irradiation, CR-39 was covered with 1 % agarose. After electrophoresis the CR-39 was taken off from the slide glass. The agarose gel on the CR-39 was stained with ethidium bromide and the opposite side of the CR-39 was etched with KOH-ethanol solution at 37 . We observed that the ion particles with higher LET value induced the heavier DNA damage, even by the same number of ion-hits within the irradiated cells.