Untersuchungen zur Wirkungsweise eines die UV-Empfindlichkeit bestimmenden Gens der Bakteriophagen T2 und T4

Summary

• 1. The phage geneu, determining the difference in UV-sensitivity between T2 and T4, is shown to act by some cellular reactivation mechanism. I.e., the primary UV-lesions are identical in both phage types, but the presence of theu-allele in T4 (as opposed to theu ⁺-allele in T2) results in reactivation of about 50% of the otherwise lethal damages. For the T4-like survival it is sufficient to have an intactu-allele within the phage-bacterium complex, but not necessarily within the proper phage to be reactivated.

• 2. The sensitivity of theu-gene, relative to the total UV-sensitivity of T2, is determined to be about (0,9±0,2)%.

• 3. Lethal UV-damages reactivable by theu-allele action are almost identical with photoreactivable damages. They do not concern preferentially genetic material with early intracellular function. At an intracellular stage, where theu-phage sensitivity is reduced to about 1/6 the original one (Luria-Latarjet-effect), theu-phage sensitivity is also reduced to 1/6.

• 4. Marker rescue experiments withu- andu ⁺-phage led to the conclusion that the UV-damages reactivable by theu-allele action are destributed widely over a large part of the genome, with the exception of ther II-region (or at least one of the twor II-cistrons). The latter was confirmed by experiments on survival of phenotype of thisr II-cistron.

• 5. The results are discussed with respect to the extent of different kinds of UV-damages and the relations between them.