Signaling during swarmer cell differentiation

描述：(申请人提供)我们的研究重点是研究 导致鼠伤寒沙门氏菌分化为 在固体生长表面上繁殖的超纤维化的海绵细胞。 从这些研究中获得的知识将扩展到生物膜领域。 和致命性。蜂群分泌的“黏液”主要由 多糖；生物膜是“粘液层”内的细菌菌落，它 在感染的持久性方面起着重要作用。我们目前的假设 粘液至少在两个方面对蜂群是必不可少的：提供了 环境是蜂群运动的环境，是蜂群细胞的信号 差异化。初步结果排除了特定信号的可能性 氨基酸，pH变化，氧气，铁饥饿，粘度增加， 鞭毛旋转或已知的自动诱导系统。广泛转座子 诱变导致大量突变体的隔离，其中大多数 在内毒素(LPS)合成方面存在缺陷，大量存在缺陷 在趋化信号通路中，还有一些可能存在缺陷 双组件信令组件。WAAG(脂多糖核心修饰)的突变： 分泌大量粘液，表现为早熟成群表型。 我们认为0-抗原改善了表面所需的“润湿性”。 对于蜂群的扩张，内毒素核心可以在粘液中扮演一个角色 以及多个双组分系统协同推动 蜂群细胞分化。我们建议1.调查 已知的趋化信号系统在SWARMER细胞分化中的作用。 研究两个新发现的双组分信号转导的作用 成群和致病的系统，以及3.测试多糖的潜力 蜂拥而至的信号，并了解粘液与 移动的蜂群细胞和贴壁细菌在生物膜中分泌的细胞。

DESCRIPTION: (provided by the applicant) The focus of our research is to study signaling mechanisms that lead to differentiation of S.typhimurium into hyperfiagellated swarmer cells when propagated on a solid growth surface. Knowledge gained from these studies will be extended to the area of bioflims and virulence. A swarmer colony secretes 'slime' which is mainly composed of polysaccharides; biofilms are bacterial colonies within 'slime layers', which play an important role in the persistence of infections. Our current hypothesis is that slime is essential for swarming in at least two ways: provides the milieu for swarming motility, and constitutes the signal for swarmer cell differentiation. Preliminary results have ruled out signals such as specific amino acids, pH changes, oxygen, iron starvation, increased viscosity, flagellar rotation or known autoinducer systems. Extensive transposon mutagenesis has led to the isolation of swarming mutants, a majority of which were defective in lipopolysaccharide (LPS) synthesis, a large number defective in the chemotaxis signaling pathway, and some defective in putative two-component signaling components. A mutation in waaG (LPS core modification): secreted copious amounts of slime and showed a precocious swarming phenotype. We have suggested that the 0-antigen improves surface 'wettability' required for swarm colony expansion, that the LPS core could play a: role in slime generation, and that multiple two-component systems cooperate to promote swarmer cell differentiation. We propose to 1. Investigate the role of the well-understood chemotaxis signaling system in swarmer cell differentiation, 2. Investigate roles of two of the newly implicated two-component signaling systems in swarming and in virulence, and 3. Test polysaccharides as potential swarming signals, and understand the relationship between slime elaborated by moving swarmer cells and that secreted by adherent bacteria in bioflims.