Effects of Prior Alteration in Nucleic Acid and Protein Metabolism on Subsequent Macromolecular Synthesis by Irradiated Bacteria

described the alteration of the killing effect of X rays on Escherichia coli resulting from prior unbalanced growth. The possibility that the treatments by which the synthesis of protein, deoxyribonucleic acid (DNA), and ribonucleic acid (RNA) could be separated, would be re-flected in altered postirradiation synthesis was next investigated. A preliminary report (Billen, 1959b) suggested that the DNA synthesizing mechanism of bac-teria, like that of animal cells, was composed of a radiosensitive and radioresistant system. These results plus the data presented here show that postirradiation synthesis of nucleic acids is markedly influenced by prior alteration in the