The Effect of track structure on the induction of DNA damage

Wada, Seiichi; Kobayashi, Yasuhiko; Funayama, Tomoo; Sakashita, Tetsuya; Hamada, Nobuyuki*; Kakizaki, Takehiko*

no journal, , 

The different particles indicate different biological effects even if their LET value is same. This difference in the biological effects by different particles with same LET is considered to be caused by a difference in their pattern of energy deposition in the target materials. However, there are very small evidences that the difference in track structure result to the different biological effects. Thus we investigated the biological effects of the track structure by different particles with the same LET value using visualization of DNA damage induced by hit-ions.CHO-K1 cells attached on ion track detector CR-39 were irradiated with the same LET value (about 437 keV/m) but different nuclide (12C and 20Ne). DNA strand breaks were immunohistochemically detected with tdt for total breaks, and with H2AX antibody for double strand breaks only. The fluorescent signal observed in nuclei by immunochemistry was co-localized at the site of etched pit where the ion was traversed on the cell. To evaluate the spatial distribution of DNA damage, the diameter of the area of fluorescent signal was measured. The area of H2AX induced by C ion and Ne ion were not significantly different, however, the area of DNA strand breaks induced by Ne ion was larger than that induced by C ion. This result indicates that the difference of ion track structure influences the pattern of induction of DNA damage.