The differential effect of x-irradiation on the incorporation of various precursors into rat thymus deoxyribonucleic acid

The effects of X- and γ-radiation on nucleic acid metabolism in the rat in vivo and in vitro

“…Irradiation considerably depressed the incorporation into the purine deoxynucleotides, that into the pyrimidine nucleotides being less affected. Harrington & Lavik's (1955) data are difficult to compare with ours, as the DNA was examined at 24 hr. after 100 r. They did, however, obtain an inhibition of uptake of 32p.…”

“…The Effects of Xand y-Radiation on Nucleic Acid Metabolism in the Rat in vivo and in vitro By MARGERY G. ORD AND L. A. STOCKEN Biochemistry Department, University of Oxford (Received 8 September 1955) The effects of X-radiation on nucleic acid metabolism and on nucleoproteins have been investigated extensively (Euler & Hevesy, 1942;Holmes, 1947;Hevesy, 1955). Recently, the emphasis has shifted to an analysis of the differential effects on the base, sugar and phosphate components (Harrington & Lavik, 1955) and to the correlation of deoxyribonucleic acid (DNA) sensitivity with position in the mitotic cycle (Howard & Pelc, 1951;Holmes & Mee, 1954;Lajtha, Oliver & Ellis, 1954). Previous experiments had demonstrated that there was no direct effect of y-rays on oxidative phosphorylation by rat-spleen mitochondria in vitro .…”

Ciba Foundation symposium on ionizing radiations and cell metabolism

“…(1) Harrington and Lavik (1955) found that the incorporation of [8-i4C]adenine into DNA purines of rat thymus, during the period 30 minutes to 24 hours after 100 r whole body X-rays, was significantly greater than in controls. In the same experiment the incorporation of [2-i*C]orotic acid into DNA pyrimidines and of^^C-formate into purines was Influence of Radiation on DNA Metabolism 197 depressed.…”

“…In some tissues (Holmes and Mee, 1955;Harrington and Lavik, 1955) the efPect of 100 to 150 r in reducing DNA turnover can be clearly seen. While these doses are much lower than those required to alter measurably many other processes of cell metabolism, they are well above the minimum for causing delays in the mitotic cycle.…”