磷酸饥饿诱导大肠杆菌同步化

用改良的Ｋｅｐｅｓ磷酸饥饿法诱导大肠杆菌Ｋ—１２ＡＭ１２６４同步化生长，细胞经８轮同步化步骤后可在磷酸不限制培养基中自由生长保持２～３次同步化细胞周期。Ｋ—１２ＡＭ１２６４大肠杆菌的细胞增倍和分化周期分别为５５和１５ｍｉｎ，同步化细胞周期可分达３个时相。细胞分裂期（Ｐ），细胞分裂和染色体复制起始间期（Ｑ）以及染色体复制起始和细胞分裂间期（Ｒ）。Ｒ期又可分Ｒ１和Ｒ２两个亚期。在Ｒ１亚期胸腺呼啶掺入ＤＮＡ的速度增加，在Ｒ２亚期掺入速度保持恒定。Ｒ１和Ｒ２期分别为１５和１０ｍｉｎ。

Synchronization of Escherichia coli by Phosphate Starvation

Escherichia coli (E. coli) K-- 12 IAM 1264 cells were synchronized by a modified version of phosphate starvation described by Kepes and Kepes. The cells which were obtained by repeating 8 cycles in synchronization step lasted for two or three cycles of synchrony under a free growth in phosphate non--limiting medium. The doubling time and the cell division period of this E. coli were 55 and 15 min, respecitively. The cell cycle was divided into three periods, cell division period (P ), the period between cell division and initiation of chromosome replication (Q ) and the period between initiation of chromosome replication and cell division (R). The R period was subdivided into two periods, R1 in which the rate of thymidine uptake into DNA was increasing,and R2 in which it was constant. The periods of R1 and R2 were 15 and 10 min, respectively.