Patterns of RNA synthesis in T5-infected cells. I. As studied by the technique of DNA-RNA hybridization-competition.

The RNA-labeling patterns obtained after T5 infection of Escherichia coli F agree with the patterns of protein labeling published by McCorquodale and Buchanan.(1) Three distinct classes of RNA formed sequentially during the period of viral development can be recognized by the DNA-RNA hybridization-competition technique. Class I RNA is formed within 5 minutes after the beginning of viral metabolism and corresponds to the RNA synthesized in response to infection with the 8 per cent segment of T5 DNA. Protein synthesis directed by this 8 per cent segment is required in some capacity for the cessation of class I synthesis and the beginning of the synthesis of class II at 4 to 5 min after infection. Class III RNA synthesis begins between 9 and 12 minutes. Its appearance is prevented when chloramphenicol is added immediately after complete expression of class I functions.