Finkel S, Halling C, Calendar R
Gene. 1986;46(1):65-9. doi: 10.1016/0378-1119(86)90167-8.
The old gene product of the P2 prophage interferes with plaque formation by lambda wild type phage but allows lambda phages whose red and gam genes have been deleted to form small, visible plaques (the lambda Spi- phenotype). The old gene product also kills Escherichia coli recB or recC mutants. We have cloned the old gene into the high-copy-number plasmid pBR322, where it prevents plaque formation by both lambda Spi+ and lambda Spi- phages. We transferred a DNA fragment that carries the old gene to the low-copy-number plasmid pSC101 and found that lambda Spi- phages can be selected on strains that carry this plasmid. The plasmid-borne old gene kills E. coli recB mutants, providing a selection for old- mutants.
P2原噬菌体的旧基因产物会干扰λ野生型噬菌体的噬菌斑形成，但能使红色基因和gam基因已缺失的λ噬菌体形成小的可见噬菌斑（λ Spi-表型）。该旧基因产物还会杀死大肠杆菌recB或recC突变体。我们已将旧基因克隆到高拷贝数质粒pBR322中，在此它会阻止λ Spi+和λ Spi-噬菌体形成噬菌斑。我们将携带旧基因的DNA片段转移到低拷贝数质粒pSC101上，发现携带该质粒的菌株上可以筛选出λ Spi-噬菌体。质粒携带的旧基因会杀死大肠杆菌recB突变体，从而为旧突变体提供了一种筛选方法。
