Andresdottir V, Masters M
Mol Gen Genet. 1978 Jul 11;163(2):205-12. doi: 10.1007/BF00267411.
The replication of F' lac was studied in exponentially growing cultures of E. coli B/r. The cells were pulse induced for the synthesis of beta-galactosidase and their DNA pulse labelled with 3H thymidine. The cells were then separated into age classes by centrifugation through a sucrose gradient in a zonal rotor. Plasmide replication was measured in each age fraction by three methods: the rate at which beta-galactosidase could be induced, the amount of label incorporated into CCC plasmid DNA which had been separated from chromosomal DNA on agarose gels, and the amount of label incorporated into plasmid DNA which had been separated from chromosomal DNA by ultracentrifugation through CsCl-EtBr gradients. All these methods gave the same result, that replication of F' lac occurs in cells of all ages and is not confined to a part of the cell cycle.
在大肠杆菌B/r指数生长培养物中研究了F' lac的复制。对细胞进行脉冲诱导以合成β-半乳糖苷酶，并对其DNA用3H胸腺嘧啶核苷进行脉冲标记。然后通过在区带转子中通过蔗糖梯度离心将细胞按年龄分类。通过三种方法测量每个年龄组分中的质粒复制：β-半乳糖苷酶的诱导速率、掺入到已在琼脂糖凝胶上与染色体DNA分离的CCC质粒DNA中的标记量，以及掺入到已通过CsCl-EtBr梯度超速离心与染色体DNA分离的质粒DNA中的标记量。所有这些方法都得到了相同的结果，即F' lac的复制发生在所有年龄的细胞中，并不局限于细胞周期的某个部分。
