Letter | Published:

Synthesis of Diphosphopyridine Nucleotide in Irradiated Rats

Naturevolume 187pages11241125 (1960) | Download Citation



WHEN suspensions of nuclei from thymus or spleen are incubated in vitro, adenosine monophosphate in the nuclei is phosphorylated to the triphosphate1. This phosphorylation appears to be abolished following low doses of X- or γ-radiation, given either in vitro or in vivo 2. However, the net synthesis of diphosphopyridine nucleotide in vivo following intraperitoneal injection of 0.5 gm. nicotinamide/kgm. (ref. 3) was not abolished when rats were exposed to X-radiation in doses up to 1,500 r. 3–60 min. before nicotinamide injection (Table 1); in these experiments, the pyridine nucleotide content of the tissue extracts was measured by the alcohol dehydrogenase method4. Since the synthesis of this nucleotide is restricted to the nucleus of the cell5 and requires adenosine triphosphate6, the above result suggests that appreciable amounts of adenosine triphosphate are still available to the cell nuclei during the first two or three hours after irradiation.

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    Osawa, S., Allfrey, V. G., and Mirsky, A. E., J. Gen. Physiol., 40, 491 (1957).

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    Creasey, W. A., and Stocken, L. A., Biochem. J., 72, 519 (1959).

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    Kaplan, N. O., Goldin, A., Humphreys, S. R., Ciotti, M. M., and Stolzenbach, F. E., J. Biol. Chem., 219, 287 (1956).

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    Ciotti, M. M., and Kaplan, N. O., in “Methods in Enzymology”, edit. by Colowick, S. P., and Kaplan, N. O., 3, 890 (1957).

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    Hogeboom, G. H., and Schneider, W. C., J. Biol. Chem., 197, 611 (1952). Morton, R. K., Nature, 181, 540 (1958).

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    Kornberg, A., J. Biol. Chem., 182, 779 (1950).

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    Stern, H., and Mirsky, A. E., J. Gen. Physiol., 37, 177 (1953). Keir, H. M., and Davidson, J. N., Arch. Biochem. Biophys., 77, 68 (1958).

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  1. Biology Branch, Atomic Energy of Canada, Ltd., Chalk River, Ontario

    • D. K. MYERS


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