Abstract
Several UV-sensitive (rad) mutants were tested for their responses to photolytic binding of an azide analog of ethidium. All mutants were more sensitive to killing by the photolytic treatment with this drug than normal strain but this sensitivity was dependent on the growth phase of each mutant. In late exponential phase, two mutants were classified as supersensitive (rad l, 3), while two (rad 6, 52) were more like the normal strain. Respiration-deficient (petite) mutation induction of late exponential cells was quite different from the cell killing effect. Almost all surviving cells of rad 1, 9 and normal strain were converted to petite mutants by photolytic treatment with 5-l0 μM of ethidium azide. In contrast, rad 3, rad 6 and rad 52 mutants were rather resistant. Early exponential cells of rad 6 and rad 52 were supersensitive to the killing effect while petite induction was the same as in normal strain.
