Signaling during swarmer cell differentiation

描述：（由申请人提供）我们的研究重点是研究 导致鼠伤寒沙门氏菌分化为 当在固体生长表面上繁殖时，其为超纤维化的群集细胞。 从这些研究中获得的知识将扩展到生物膜领域 和毒性。蜂群会分泌“黏液”， 生物膜是“粘液层”内的细菌菌落， 在感染的持续性中起着重要作用。我们目前的假设 粘液至少在两个方面对蜂群的形成至关重要： 群集运动的环境，并构成群集细胞的信号 分化初步结果已经排除了特定的信号， 氨基酸、pH变化、氧气、铁缺乏、粘度增加， 鞭毛旋转或已知的自诱导系统。广泛转座子 诱变导致了群集突变体的分离，其中大多数 在脂多糖（LPS）的合成缺陷，大量的缺陷 在趋化性信号传导途径中， 双组分信号组分。waaG突变（LPS核心修饰）： 分泌大量粘液并表现出早熟的群集表型。 我们已经提出，0-抗原提高了所需的表面“润湿性”， 对于群体菌落的扩张，LPS核心可能在粘液中起作用 多个双组分系统合作促进 群集细胞分化我们建议1。调查的作用 在群集细胞分化中充分理解的趋化性信号系统，2. 研究两种新涉及的双组分信号传导的作用 系统的群集和毒力，和3。测试多糖作为潜力 群集信号，并了解粘液之间的关系阐述了 移动群集细胞和生物膜中粘附细菌分泌的。

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.