Article révisé par les pairs
Résumé : Phage λ, in which thymine has been totally substituted by the analog, 5-bromouracil, have been irradiated with near visible light in the presence and absence of cysteamine, a free radical scavenger and proton donor. These phage were then assayed on normal bacteria and on mutants which are unable to repair DNA lesions. It is concluded that these phage suffer three different kinds of lesions: (1) a class which are not reparable, but which can prevented cysteamine, suggesting that they are sugar damages; (2) a class which are reparable but are not eliminated by cysteamine and (3) a class which can be neither eliminated nor repaired. The nature of the latter two types of lesions cannot be surmised at present. © 1969 Springer-Verlag.