Valenzuela M S, Aguinaga M D, Inman R B
Mol Gen Genet. 1981;181(2):241-7. doi: 10.1007/BF00268432.
By the use of a restriction enzyme digestion of gently lysed E. coli or B. subtilis cells, it is possible to isolate a minute fraction of the total DNA that has an unusually high sedimentation coefficient. Upon inspection of this DNA in the electron microscope, branched DNA fragments are observed. Single branched DNA fragments were analyzed by restriction enzyme and partial denaturation mapping techniques. The fragments appear to have the properties of growing forks excised from in vivo replicating intermediates. In B. subtilis, the minute fraction of DNA was also investigated by transformation assays and found to be greatly enriched for a marker near the origin and slightly enriched for a terminus marker.
通过对轻度裂解的大肠杆菌或枯草芽孢杆菌细胞进行限制性内切酶消化，可以分离出总DNA中极小一部分具有异常高沉降系数的DNA。在电子显微镜下检查这种DNA时，可以观察到分支状的DNA片段。通过限制性内切酶和部分变性图谱技术对单个分支DNA片段进行了分析。这些片段似乎具有从体内复制中间体切下的生长叉的特性。在枯草芽孢杆菌中，还通过转化试验对这一小部分DNA进行了研究，发现它在靠近复制起点的标记处高度富集，在终点标记处略有富集。
