Temperature-sensitive mutation. IV. Induction and characterization of a ts-mutation in RNA-containing bacteriophage R17

Temperature-sensitive mutants of the RNA phage R17 were induced by treatment with 10−5 M 5-fluorouracil. One of the temperature-sensitive mutants, ts24, was studied and the following facts were discovered: (1) ts24 undergoes eclipse at the non-permissive temperature, 43 °C. (2) If the temperature is increased to non-permissive levels before 60 min of postinfection culture, phage multiplication ceases. (3) At 43 °C, ts24 cannot synthesize progeny viral RNA. (4) Upon decreasing the temperature to permissive levels during the first 60 min of postinfection culture, RNA replication resumes almost instantaneously. It was concluded from these facts that ts24 contains a temperature-sensitive mutation in the RNA replicating function.