THE EFFECT OF CHLORAMPHENICOL ON DEOXYRIBONUCLEIC ACID SYNTHESIS AND THE DEVELOPMENT OF RESISTANCE TO ULTRAVIOLET IRRADIATION IN E. COLI INFECTED WITH BACTERIOPHAGE T2

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Abstract
To elucidate the role of protein synthesis in deoxyribonucleic acid (DNA) formation, Escherichia coli R2 infected with phage T2 was studied employing chloramphenicol to inhibit protein synthesis. The increase of DNA in infected bacteria was completely suppressed by the addition of chloramphenicol within 2 minutes following infection. Addition at later times showed progressively less inhibitory action depending upon the time interval, and addition after the 10th minute showed no appreciable effect on DNA synthesis despite the cessation of intra-cellular phage formation and protein synthesis. Thus, protein synthesis is necessary to initiate DNA synthesis but is not essential for its continuation. Chloramphenicol stopped the increase of resistance to UV irradiation whether or not DNA synthesis continued. The evolution of resistance paralleled the rate of DNA synthesis achieved, but not the amount of DNA accumulated.