BIOCHEMISTRY AND RADIATION EFFECT DURING THE CELL CYCLE

在“婴儿机器”培养系统中，细胞被固定在 表面，使新生细胞不断地从 文化。当固定化细胞分裂时，其中一个新的后代 细胞保持附着状态，另一个细胞被释放。这种文化 该系统已被用来破译许多细胞周期/DNA 大肠杆菌B/R的复制分离/细胞分裂特性。 然而，由于新生儿的数量，它的用途受到了限制 释放的细胞和无法使用的许多E.ColiK12 衍生品。认识到这两个问题都需要解决 在解决细胞周期的调控方面取得真正进展， 这台婴儿机器已经过改装，可以与大多数 微生物，细胞产量提高了5到20倍。 因此，将使用各种K12衍生品来确定 染色体调控的分子机制 复制/分离和细胞分裂。在以下项目中 将采取的措施是：1)继续对婴儿机器进行修改， 主要是为了发展细胞的共价连接，以便 开发其在细胞周期/细胞老化研究中的全部潜力 2)分析K12细胞周期参数 衍生工具，并确定组件之间的相互作用 控制染色体起始时间的电路 复制；3)测试关于定时控制的理论 K12衍生物对细胞分裂的局部调控；4)测定 低拷贝F和PI质粒在细胞内的复制模式。 5)确定非随机染色体的决定因素 隔离；6)检查与以下各项相关的OIC-包络相互作用 启动复制和分离；7)确定 超螺旋性与微染色体稳定性和稳定性的关系 8)细胞周期特异性基因转录检测。 参与启动染色体复制；9)确定 细胞周期依赖的染色体调节子的出现 体外微染色体复制系统中的复制。这个 能够进行生理上健全的细胞周期研究 产量提高的菌株K12应该有助于解决许多悬而未决的问题 关于染色体间控制和协调的几个问题 大肠杆菌中的复制/分离和细胞分裂。

In the "baby machine" culture system, cells are immobilized on a surface such that newborn cells are shed continuously from the culture. When an immobilized cell divides, one of the new progeny cells remains attached and the other is released. This culture system has been used to decipher many of the cell cycle/DNA replication-segregation/cell division properties of E. coli B/r. Its usefulness has been limited, however, by the number of newborn cells released and the inability to use the many E. coli K12 derivatives. Recognizing that both problems required solutions to make real headway in solving regulatory aspects of the cell cycle, the baby machine has been modified to function with most microorganism, and the cell yield has been increased 5 to 20-fold. Accordingly, a variety of K12 derivatives will be used to determine molecular mechanisms involved in the control of chromosome replication/segregation and cell division. Among the projects to be undertaken are: 1) Continued modifications of the baby machine, primarily to develop covalent attachment of the cells, in order to develop its full potential for cell cycle/cell aging studies with a variety of species; 2) Analyze cell cycle parameters of K12 derivatives and identify the interactions among the components of the circuit controlling the timing of initiation of chromosome replication; 3) Test theories on control of the timing and toporegulation of cell division with K12 derivatives; 4) Determine the replication patterns of low copy F and PI plasmids in the cell. cycle; 5) Identify the determinants of nonrandom chromosome segregation; 6) Examine OriC-envelope interactions in relation to initiation of replication and segregation; 7) Determine the involvement of superhelicity in minichromosome stability and partitioning; 8) Assay cell cycle-specific transcription of genes. involved In initiation of chromosome replication; 9) Identify the cell cycle-dependent appearance of modulators of chromosome replication in an in vitro minichromosome replication system. The ability to perform physiologically sound cell cycle studies using strain K12 with improved yields should help resolve many unanswered questions on the control and coordination between chromosome replication/segregation and cell division in E. coli.