X-Irradiation of Deoxyribonucleic Acid

Abstract

ONE of the biochemical effects of X-irradiation is the inhibition of synthesis of DNA. Although Okada and Hempelmann¹ showed that, after ionizing radiation, there is an inhibition of the activities of enzymes essential for DNA synthesis, the experiments of Bollum et al.² indicate that regenerating rat liver can still synthesize thymidylic kinase and DNA polymerase in tissues where DNA synthesis has been suppressed by X-irradiation. Walwick and Main³ reported that the enzymes catalysing synthesis of DNA are unaffected by X-radiation at dose-levels (100–5,000 rads) ordinarily encountered in radiation biology. Stacey⁴ found that the ability of X-irradiated DNA to ‘prime’ the action of polymerase is reduced, but only by relatively high doses.