Analysis for complexity of clustered DNA damage generated by heavy ion beams.

Among numerous DNA damaging factors, ionizing radiation produces the damage showing very unique structure. Since ionizing radiation passes through a target DNA as a beam, the respective induced lesions locate close together around the track. Such damage aggregation on target DNA called "clustered DNA damage" is thought to be a major cause of the specific and serious effect of ionizing radiation. However, we have less knowledge about the structure of clustered DNA damage, which seems very important in its biological impact. Therefore, we evaluated procedure to analyze the structure of clustered DNA damage induced by ionizing radiation. In the present study, we used polyacrylamide gel electrophoresis to separate oligodeoxyribonucleotide (ODN) substrates containing clustered DNA damage with post-modification with aldehyde reactive probe. The designed procedure well counted the number of abasic site in the model substrate of clustered DNA damage.