Rambach A, Tiollais P
Proc Natl Acad Sci U S A. 1974 Oct;71(10):3927-30. doi: 10.1073/pnas.71.10.3927.
A derivative of lambda b221 that has lost by mutation all EcoRI restriction sites has been isolated by alternative growth on restrictive and nonrestrictive strains. It has an efficiency of plating equal to 1 on the restrictive strain. Genetic cross of this bacteriophage with lambda plac5 imm21 gave rise to recombinants of intermediate restricting ratios. The analysis of the EcoRI endonuclease-cleaved DNA by polyacrylamide gel electrophoresis, compared with the genetic results, has permitted identification of EcoRI endonuclease cleavage sites in the recombinants. The genotypes are: lambda plac5 CI857 sRIlambda3(0)sRIlambda2(0)sRIlambda1(0) and lambda plac5 CI857 sRIlambda2(0)sRIlambda1(0). The remaining cleavage sites, respectively, sRIlac sRIlambda4 and sRIlac sRIlambda4 sRIlambda3, are all located in a region nonessential for bacteriophage multiplication. The involvement of these mutant bacteriophages as vector for foreign genes are discussed.
通过在限制型菌株和非限制型菌株上交替培养，分离出了λb221的一种衍生物，该衍生物因突变而失去了所有EcoRI限制位点。它在限制型菌株上的平板接种效率等于1。这种噬菌体与λplac5 imm21进行遗传杂交，产生了具有中间限制比例的重组体。通过聚丙烯酰胺凝胶电泳对EcoRI核酸内切酶切割的DNA进行分析，并与遗传结果进行比较，从而确定了重组体中的EcoRI核酸内切酶切割位点。基因型为：λplac5 CI857 sRIlambda3(0)sRIlambda2(0)sRIlambda1(0)和λplac5 CI857 sRIlambda2(0)sRIlambda1(0)。其余的切割位点，分别为sRIlac sRIlambda4和sRIlac sRIlambda4 sRIlambda3，都位于噬菌体繁殖非必需的区域。文中讨论了这些突变噬菌体作为外源基因载体的作用。
