Investigation and repairability elucidation of inter-strand crosslinked DNA produced by ionizing radiation

Inter-strand cross-linked DNA, which is one of DNA damages by irradiation and difficult to repair, was investigated. Dried DNA membranes of plasmid, pUC19 were irradiated by soft X-ray and 60Co gamma-ray. The irradiated DNA membranes were analyzed by agarose electrophoresis. Signals of higher molecular weight than the one of original DNA membrane were obtained by both of the irradiations. The measurement results were expected that gel or cross-linked compounds of DNA were formed by the irradiation. Sum of separated base quantity out of the irradiated DNA and undamaged nucleoside quantity obtained by enzyme treatment couldn't reach to total base quantity of original DNA. It was considered that blocking of enzyme reaction took place on base defective parts, cross-link parts and damaged base parts. (M. Suetake)