Chronology of viral functions in bacteriophage alpha.

Temperature-sensitive mutants of phage alpha were subjected to short pulses of permissive temperature at various times during the lytic cycle. All the mutants showed an optimal response to the permissive pulse at a specific time after infection. The optimal responses of the mutants belonging to the same complementation group fell close together in the same time interval; the optimal responses of mutants contained in 20 different complementation groups were more or less uniformly scattered throughout the lytic cycle. Temperature sensitivity, therefore, seems to afford, at least in the case of phage alpha, an independent way of grouping the genes in an ordered sequence with respect to the steps they control.