Allman R, Schjerven T, Boye E
Department of Biophysics, Institute for Cancer Research, Montebello, Oslo, Norway.
J Bacteriol. 1991 Dec;173(24):7970-4. doi: 10.1128/jb.173.24.7970-7974.1991.
A computer simulation routine was used to calculate the DNA distributions of exponentially growing cultures of Escherichia coli K-12. Simulated distributions were compared with distributions obtained experimentally by flow cytometry. Durations of the DNA replication period (C) and the postreplication period (D) were found by minimizing the difference between theoretical and experimental DNA histograms. It was demonstrated that the K-12 strains AB1157 and CM735 had C and D periods that differed widely from each other and from those of the previously measured strain B/rA, while strain MC1000 was shown to have the same durations of the C and D periods as strain B/rA. The variation between K-12 strains may explain the divergence in the literature regarding their C and D periods. Strains W3110 and AB1157 recA1 had DNA histograms that could not be adequately simulated by the classical Cooper-Helmstetter model, which is consistent with the asymmetrically located origin and terminus for W3110 and the asynchrony of initiation for AB1157 recA1.
利用计算机模拟程序计算了大肠杆菌K-12指数生长培养物的DNA分布。将模拟分布与通过流式细胞术实验获得的分布进行了比较。通过最小化理论和实验DNA直方图之间的差异，确定了DNA复制期（C）和复制后期（D）的持续时间。结果表明，K-12菌株AB1157和CM735的C期和D期彼此之间以及与先前测量的菌株B/rA的C期和D期有很大差异，而菌株MC1000的C期和D期持续时间与菌株B/rA相同。K-12菌株之间的差异可能解释了文献中关于它们的C期和D期的分歧。菌株W3110和AB1157 recA1的DNA直方图无法用经典的库珀-赫尔姆斯泰特模型充分模拟，这与W3110的起始点和终点不对称定位以及AB1157 recA1起始的不同步性一致。
