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THE EFFECT OF CHLORAMPHENICOL ON DEOXYRIBONUCLEIC ACID SYNTHESIS AND THE DEVELOPMENT OF RESISTANCE TO ULTRAVIOLET IRRADIATION IN E. COLI INFECTED WITH BACTERIOPHAGE T2 BY JUN-ICHI TOMIZAWA Ax, ro SUMIK0 SUNAKAWA

In spite of its capital importance, the mechanism of deoxyribonucleic acid (DNA) synthesis remains quite obscure. One of the main reasons for this is the complicated correlations between the synthesis of DNA and other cellular constituents in cells. In phage-infected bacteria the metabolic pathways shunt to phage formation, resulting in production mainly of DNA and protein. Thus the system is considerably simplified, giving a good model for DNA synthesis. Furthermore, the blendor experiment by Hershey and Chase (1) suggested that the parental DNA plays a dominant role in initiating phage infection. An understanding of the mode of action of the injected DNA in the initiation of subsequent synthesis of DNA is strongly to be desired. The present study points to a role for protein synthesis as a prerequisite to DNA synthesis. Deriving the experimental principle from the report of Wisseman et al. (2) that chloramphenicol selectively inhibits the synthesis of protein without affecting that of DNA in E. coli, use was made of this agent to inhibit protein synthesis in infected cells. At the same time ultraviolet (UV) analysis, one of the most penetrating methods available for following the progress of the infective process, was performed with or without the addition of chloramphenicol.