Radiation sensitive mutants of phage T4

Summary A comparative series of phage survival, multiplicity reactivation and radiation stability experiments have been performed with single and double combinations of the four UV-sensitive mutations v, x, y and 1206. These mutations appear to fall into two groups with v (which is associated with excision repair) in one, and x, y and 1206 (associated with what can be non-committally termed replication repair) in the other. The pattern of the results suggest that the extent of the initial shoulder exhibited by multiplication reactivation curves is determined by replication repair, while the slope of the subsequent linear portion depends on excision repair. The development of the characteristic radiation stability observed in Luria-Latarjet experiments is shown to depend to a major extent on replication repair and only in a minor way on excision repair.