CELL DIVISION AND SURFACE GROWTH IN A "MODEL" SYSTEM

提出了两个相互关联的模型，描述了：1） 通过染色体复制的粪链球菌表面生长;和2）a 引导包膜前体组装的形状决定机制 进入新的细胞表面。 第一个模型提供了在一轮染色体合成期间， 这导致了生长区的形成。 这个网站，一旦 形成，扩大细胞表面，直到第二个信号，产生在 染色体复制的终末阶段，抑制扩大和促进 分隔 第二个模型是关于增长的结构和功能 区一旦形成。 该模型表明，表面生长 通过细胞壁前体基本上沿着进入生长区的调节流动 两个频道。 一个通道将组装双层横壁（可能通过 将前体添加到横壁的前缘），而 前体的第二通道将该横壁转化成两层 外周壁 在染色体终止信号的影响下， 前体沿着该第二通道的流动将逐渐减少 周期的后半部分。 这种减少加上持续的流动， 前体进入跨壁合成可能导致细胞分裂。 已经设计出可以将包络的几何形状与 细胞的大分子含量和自溶活性。 在试图 测试上述模型的许多方面，这些方法将被应用到 稳态、同步和不平衡群体，其中特异性抑制 DNA、RNA、蛋白质或细胞壁的生物合成。

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.