Hercules K, Munro J L, Mendelsohn S, Wiberg J S
J Virol. 1971 Jan;7(1):95-105. doi: 10.1128/JVI.7.1.95-105.1971.
Wild-type bacteriophage T4 was enriched for mutants which fail to degrade Escherichia coli deoxyribonucleic acid (DNA) by the following method. E. coli B was labeled in DNA at high specific activity with tritiated thymidine ((3)H-dT) and infected at low multiplicity with unmutagenized T4D. At 25 min after infection, the culture was lysed and stored. Wild-type T4 degrades the host DNA and incorporates the (3)H-dT into the DNA of progeny phage; mutants which fail to degrade the host DNA make unlabeled progeny phage. Wild-type progeny are eventually inactivated by tritium decay; mutants survive. Such mutants were found at a frequency of about 1% in the survivors. Eight mutants are in a single complementation group called denA located near gene 63. Four of these mutants which were examined in detail leave the bulk of the host DNA in large fragments. All eight mutants exhibit much less than normal T4 endonuclease II activity. The mutants produce somewhat fewer phage and less DNA than does wild-type T4.
通过以下方法富集不能降解大肠杆菌脱氧核糖核酸（DNA）的野生型噬菌体T4突变体。用氚标记的胸腺嘧啶核苷（³H-dT）以高比活性标记大肠杆菌B的DNA，并用未诱变的T4D以低感染复数进行感染。感染后25分钟，裂解培养物并储存。野生型T4降解宿主DNA并将³H-dT掺入子代噬菌体的DNA中；不能降解宿主DNA的突变体产生未标记的子代噬菌体。野生型子代最终会因氚衰变而失活；突变体存活下来。在存活者中发现此类突变体的频率约为1%。八个突变体属于一个称为denA的单一互补群，位于基因63附近。详细检测的其中四个突变体使大部分宿主DNA保持为大片段。所有八个突变体的T4内切核酸酶II活性均远低于正常水平。与野生型T4相比，这些突变体产生的噬菌体和DNA略少。
