Spleen desoxyribonucleic acid content as an index of recovery in x-radiated mice treated with spleen homogenate.

From the biochemical standpoint, perhaps the most striking effect of ionizing radiations on living systems involves a defect in the metabolism of the nucleic acids. Thus, one can cite a large number of observations in the literature (1, 18, 14, 16, @8) which state that the incorporation of a variety of labeled precursor substances (inorganic phos phate, formate, NaHCO5, glycine) into tissue desoxyribonucleic acid (DNA) is markedly in hibited following the exposure of laboratory ani mals to x-radiation. The inhibition appears to be most pronounced in tissues with high DNA re newal rates (1@) and rapid cell turnover, such as spleen, bone marrow, intestinal mucosa, and thymus. It is of interest, furthermore, that this inhibitory effect of ionizing radiations is rather