Chakrabarti S, Gorini L
J Bacteriol. 1975 Feb;121(2):670-4. doi: 10.1128/jb.121.2.670-674.1975.
Streptomycin-resistant mutants of an Hfr strain of Escherichia coli K were examined for their ability to support the growth of male-specific ribonucleic acid phage MS2 and female-specific deoxyribonucleic acid phage T7. Normally, the Hfr strain allows propagation of MS2 and is lysed by it (efficiency of plating equal to 1), whereas the same strain restricts propagation of T7 and is not lysed by it (efficiency of plating smaller than 10-7). Twenty-four isolates out of 26 independently obtained streptomycin-resistant mutants are partially or completely derestricted for propagation of T7; efficiency of plating of T7 in such strains ranges from 10-3-1. Depending on their response to plating of MS2 and T7, the streptomycin-resistant mutants can be divided into four classes. The mutants in all four classes continue to be "male" in conjugation with F- strains. Genetic analysis is presented to show that restriction of MS2, derestriction of T7, and resistance to streptomycin are the pleiotropic effects of a single mutation at the strA locus.
对大肠杆菌K的一个Hfr菌株的链霉素抗性突变体进行了检测,以考察它们支持雄性特异性核糖核酸噬菌体MS2和雌性特异性脱氧核糖核酸噬菌体T7生长的能力。正常情况下,该Hfr菌株允许MS2繁殖并被其裂解(平板接种效率等于1),而同一菌株限制T7繁殖且不被其裂解(平板接种效率小于10-7)。在26个独立获得的链霉素抗性突变体中,有24个分离株对T7繁殖的限制被部分或完全解除;T7在此类菌株中的平板接种效率范围为10-3至1。根据它们对MS2和T7平板接种的反应,链霉素抗性突变体可分为四类。所有四类突变体在与F-菌株接合时仍为“雄性”。遗传分析表明,MS2的限制、T7的解除限制以及对链霉素的抗性是strA位点单一突变的多效性效应。