GENE EXPRESSION DURING SPORULATION

芽孢杆菌和梭菌的孢子形成是细胞分化的原始系统。 它涉及到一个不对称的分裂。 这就产生了两种不同的细胞类型，母细胞和前孢子，它们具有根本不同的发育命运。 前孢子被母细胞吞噬，发育成成熟的耐热孢子. 母细胞是发育所必需的，但最终会溶解。 在枯草芽孢杆菌中，已经表明两种RNA聚合酶σ因子F和E在分裂时被激活，其中σ F仅在前孢子中活性，σ E仅在母细胞中活性。 这些σ因子指导区室化基因表达的后续程序，但不指导区室化的过程。主要问题是如何建立基因表达的区室化，以及基因表达如何与形态学变化相协调。 在芽孢杆菌和梭菌的区室化思维中，一个主要的特征是孢子形成分裂的位置非常不对称。 有人建议测试其他可能的决定因素的划分在一个物种的孢子形成球菌，孢子八叠球菌，其中孢子形成司是对称的。 建议开发一个两部分系统，测试划分的完整性。 该系统将用于搜索和表征B。具有受损的区室化的枯草杆菌突变体。 它也将被用来测试在S.不稳定。 建议探索SpoIIE蛋白的需求以便在B中具有不对称分裂。枯草杆菌。 建议测试染色体分辨在孢子形成中的作用。 建议鉴定和表征参与B中母细胞吞噬前孢子的基因。枯草杆菌。

Formation of spores by species of Bacillus and Clostridium is a primitive system of cell differentiation. It involves an asymmetrically located division. This gives rise to two distinct cell types, the mother cell and the prespore, which have radically different developmental fates. The prespore is engulfed by the mother cell and develops into the mature, heat- resistant spore. The mother cell is required for that development but ultimately lyses. In Bacillus subtilis it has been shown that two RNA polymerase sigma factors, F and E, are activated upon division, with sigmaF active exclusively in the prespore and sigmaE active exclusively in the mother cell. These sigma factors direct the subsequent program of compartmentalized gene expression, but do not direct the process of compartmentalization. The main problems being addressed are how compartmentalization of gene expression is established and how gene expression is coordinated with morphological changes. A dominant feature in the thinking about compartmentalization in Bacilli and Clostridia has been the grossly asymmetric location of the sporulation division. It is proposed to test for other possible determinants of compartmentalization in a species of spore-forming coccus, Sporosarcina ureae, in which the sporulation division is symmetrically located. It is proposed to develop a two-part system that tests the completeness of compartmentalization. This system will be used to search for and characterize B. subtilis mutants with impaired compartmentalization. It will also be used to test the completeness of compartmentalization in S. ureae. It is proposed to explore the requirement for the SpoIIE protein in order to have an asymmetric division in B. subtilis. It is proposed to test the role of chromosome resolution in spore formation. It is proposed to identify and characterize genes involved in engulfment of the prespore by the mother cell in B. subtilis.