CELL DIVISION AND SURFACE GROWTH IN A "MODEL" SYSTEM

提出了两个相互关联的模型，它们描述了：1)调节 通过染色体复制的粪链球菌表面生长；和2)a 指导包络前驱体组装的形状确定机构 进入新的细胞表面。 第一个模型规定，在一轮染色体合成过程中，信号是 产生导致形成生长带的物质。这个网站，曾经 形成，扩大细胞表面，直到第二个信号，在 染色体复制的终末阶段，抑制放大并促进 分隔符。 第二个模型是关于成长的结构和功能。 一旦它形成，就会有一个新的区域。这个模型表明，表面生长继续进行。 通过细胞壁前体的受控流动进入生长区，基本上是沿着 两个频道。一条通道将组装成双层横壁(可能通过 将前体添加到横墙的前缘)，而一个 前驱体的第二通道会将这种交叉墙转化为两层 外围墙。在染色体终止信号的影响下， 沿着这第二个通道的前体流量将在#年逐渐减少 周期的后半部分。这种减少与持续的流动相结合 前体进入跨壁合成可导致细胞分裂。 已经设计了一些方法，可以将信封的几何形状与 细胞的大分子含量和自溶活性。在试图 对上述模型进行了多方面的测试，这些方法将应用于 稳态、同步和不平衡的种群，其中特定的抑制 DNA、RNA、蛋白质或壁的生物合成已被诱导。

Two interrelated models have been presented which describe: 1) the regulation of surface growth of Streptococcus faecalis by chromosome replication; and 2) a shape-determining mechanism which directs the assembly of envelope precursors into new cell surface. The first model provides that during a round of chromosome synthesis a signal is produced which results in the formation of a growth zone. This site, once formed, enlarges the cell surface until a second signal, produced during the terminal stages of chromosome replication, inhibits enlargement and promotes septation. The second model is concerned with the construction and function of the growth zone once it has been formed. This model suggests that surface growth proceeds by a regulated flow of cell wall precursors into a growth zone essentially along two channels. One channel would assemble a bilayered cross wall (possibly by the addition of precursors to the leading edge of the cross wall), while a second channel of precursors would convert this cross wall into two layers of peripheral wall. Under the influence of the chromosome termination signal, the flow of precursors along this second channel would be progressively reduced in the latter portion of the cycle. This reduction coupled with the continued flow of precursors into cross wall synthesis could result in cell division. Methods have been devised which can compare the geometry of the envelope with the macromolecular content and autolytic activity of cells. In attempting to test many aspects of the above models, these methods will be applied to steady-state, synchronous, and unbalanced populations where specific inhibition of DNA, RNA, protein, or wall biosynthesis has been induced.