Cross R A, Lieb M
J Virol. 1970 Jul;6(1):33-41. doi: 10.1128/JVI.6.1.33-41.1970.
Mutations in gene N of lambda prevent killing of the host bacterium after infection. However, derepression of Nsus prophages in nonpermissive (pm(-)) bacteria results in death of the lysogens. When prophages in pm(-)(lambdaCItsA-Nsus) lysogens are derepressed by raising the temperature to 45 C, the cells remain viable as long as they are at 45 C. However, they cannot form colonies at 33 C unless they have been superinfected, at the high temperature, by lambdaCI(+)-Nsus phage which produces repressor at 45 C. A large fraction of these "rescued," heat-inducible lysogens are lysogenized by the superinfecting phage, but lysogenization is not required for rescue. In pm(-)(lambdaCItsA-Nsus) lysogens growing at 45 C, the rate of deoxyribonucleic acid (DNA) synthesis shows a characteristic increase after the temperature is lowered. This increased DNA synthesis, which is correlated with loss of rescue potential, does not occur as long as the cultures are maintained at 45 C.
λ噬菌体N基因的突变可防止感染后宿主细菌被杀死。然而，在非允许性（pm(-)）细菌中，Nsus原噬菌体的去阻遏会导致溶源菌死亡。当pm(-)(λCItsA-Nsus)溶源菌中的原噬菌体通过将温度升高到45℃去阻遏时，只要它们处于45℃，细胞就仍具活力。然而，除非它们在高温下被能在45℃产生阻遏物的λCI(+)-Nsus噬菌体超感染，否则它们在33℃不能形成菌落。这些“获救的”、热诱导溶源菌中的很大一部分被超感染噬菌体溶源化，但获救并不需要溶源化。在45℃生长的pm(-)(λCItsA-Nsus)溶源菌中，温度降低后，脱氧核糖核酸（DNA）合成速率呈现出特征性增加。这种与获救潜力丧失相关的DNA合成增加，只要培养物维持在45℃就不会发生。
