Bacteriophage lambda containing two temperature-sensitive mutations in the cl gene produces clear plaque at 30°

Abstract

When λcIts2Psus3 was crossed with λNsus7sus53cI857, clear plaque formers at 30° were obtained among the λN⁺P⁺ recombinants. This clear recombinant of λ was shown to contain the two cIts mutations, 2 and 857, of the parents. It was also observed that crosses between any two λcIts mutants, from a list of eight, produced recombinants forming clear plaques at 30°. These suggest that no pair of ts mutations of the eight tested are compatible with the functioning of the repressor even at 30° when they are present in cis.