RADIATION-SENSITIVE MUTANTS OF T4D .2. T4Y - GENETIC CHARACTERIZATION

A complementation system for radiation-sensitive phage mutants is described. The mutants v, x and y are shown to belong to three distinct cistrons having the wild-type allele dominant in each case. The UV-survival curves of the phenotypes of these cistrons are distinct, with sensitivities, relative to the mutant phage sensitivities, of 1.6, 3.2 and 6.8% for v, y and x respectively. Mapping experiments show the 3 mutations to be unlinked. The UV-survival properties of the double mutants vx, vy and xy are compared, and the results strongly support the hypothesis that x and y form a class of radiation-sensitive mutants which function in a manner different from v. Some possible functions of x and y are discussed. © 1969.