E. coli Colony Development

表面生长是自然界细菌活动的一个关键特征。大肠杆菌菌落是细菌表面种群的优良模型系统。它是一个高度组织化的结构，以差异基因表达为特征。细胞间在微米距离上的相互作用调节着单个细胞的生长，而基因表达模式可以在毫米距离上的种群之间进行协调。扩散性信号影响群体发育的几个方面。通过自发和转座子插入突变以及lacZ融合，已经确定了在群体发育过程中受差异控制的遗传位点。此外，cAMP系统还与激活Mudiac元素的空间局部复制有关。实验计划将通过对三个系统的详细研究来扩展这些初步观察：(1)dev1891::lacZ融合的发育调节。(2) DNA聚合酶1、cAMP系统和扩散物质在控制Mudiac复制中的作用；(3)位于染色体oriC区的dev2137和dev2137突变。研究结果将详细说明参与集落形态发生的基因产物，提供琼脂表面生长过程中差异基因表达的更详细图像，并确定影响集落发育的扩散信号。

Surface growth is a key feature of bacterial action in nature. The E. coli colony is an excellent model system of bacterial surface populations. It is a highly organized structure characterized by differential gene expression. Cell-cell interactions over distances of microns regulate the growth of individuals cells, and gene expression patterns can be coordinated between populations separated by distances of millimeters. Diffusible signals affect several aspects of colony development. Genetic loci subject differential control during colony development have been identified by spontaneous and transposon insertion mutations and the use of lacZ fusions. In addition, the cAMP system has been implicated in activating the spatially localized replication of Mudiac elements. The experimental program will extend these initial observations by detailed study of three systems:(1) developmental regulation of the dev1891::lacZ fusion. (2) the role of DNA polymerase 1, the cAMP system, and diffusible substances in the control of Mudiac replication, and (3) the dev2137 and dev2137 mutations located in the oriC region of the chromosome. The results will specify gene products involved in colony morphogenesis, provide a more detailed picture of differential gene expression during growth on an agar surface, and identify diffusible signals that affect colony developments.