Benzinger R, Kleber I, Huskey R
J Virol. 1971 May;7(5):646-50. doi: 10.1128/JVI.7.5.646-650.1971.
The addition of 25 mug of protamine sulfate per ml to lysozyme-ethylenediamine-tetraacetic acid spheroplasts of Escherichia coli stimulates transfection not only for T1 phage deoxyribonucleic acid (DNA; Hotz and Mauser, 1969) but also for the following phage DNA species: lambda, 10,000-fold to an efficiency of 10(-3) infective centers per DNA molecule; phiX174 replicative form, 300-fold to an efficiency of 5 x 10(-2); fd replicative form, 300-fold to 10(-6); T7, 300-fold to 3 x 10(-7). Three native phage DNA species were not infective at all in the absence of protamine sulfate but were infective in the presence of protamine sulfate with the following efficiencies: T4, 10(-5); T5, 3 x 10(-6); and P22, 3 x 10(-9). The effect of protamine sulfate is specific for double-stranded DNA. The application of infectivity assays to the study of phage DNA replication, recombination, prophage integration, prophage excision, and interspecies transfection are discussed.
向大肠杆菌的溶菌酶 - 乙二胺四乙酸原生质球每毫升添加25微克硫酸鱼精蛋白，不仅能刺激T1噬菌体脱氧核糖核酸（DNA；霍茨和毛泽，1969）的转染，还能刺激以下噬菌体DNA种类的转染：λ噬菌体，提高10000倍，达到每个DNA分子产生10⁻³个感染中心的效率；φX174复制型，提高300倍，达到5×10⁻²的效率；fd复制型，提高300倍，达到10⁻⁶；T7噬菌体，提高300倍，达到3×10⁻⁷。三种天然噬菌体DNA种类在没有硫酸鱼精蛋白时完全没有感染性，但在有硫酸鱼精蛋白时具有感染性，效率如下：T4噬菌体，10⁻⁵；T5噬菌体，3×10⁻⁶；P22噬菌体，3×10⁻⁹。硫酸鱼精蛋白的作用对双链DNA具有特异性。本文还讨论了感染性测定在噬菌体DNA复制、重组、原噬菌体整合、原噬菌体切除和种间转染研究中的应用。
