Radiation sensitivity of DNA molecules in situ in normal and neoplastic tissues of mice.

The sensitivity to radiation of DNA molecules in situ in various tissues was estimated by alkaline sucrose gradient centrifugation. The sensitivity of DNA in liver, thymus, spleen and cerebellum was found to be of the same order of magnitude. The oxygen enhancement ratios of DNA in spleen, thymus and cerebellum were all approximately three. Sensitivity of DNA molecules in the tumour was about half of that in normal tissues, probably because of its hypoxicity.