Study of the interplay of motility mechanisms during swaming of Myxococcus xanthu

描述（由申请人提供）：在生物学中最重要的新兴行为之一是群体形成。许多种类的细菌聚集在一起，包括在不同的土壤和水环境中发现的物种，如枯草芽孢杆菌、液化沙雷氏菌、神奇变形杆菌、铜绿假单胞菌和黄粘球菌。这些和其他群居细菌的用途范围广泛，从无害的碳循环生物到有害的病原体。在细胞中观察到蜂群是由旋转鞭毛、粘液分泌和IV型毛的收缩推动的。细菌在基质上移动，并以一种改善细胞物理相互作用和优化群体的方式改变其局部环境。M. xanthus是一种杆状的革兰氏阴性黏菌，它能够通过两个基因独立但又相互合作的a和S运动引擎在表面上滑行。这些细菌产生黏液，并沿着菌落其他成员产生的黏液轨道移动。值得注意的是，这些细菌也有规律地逆转它们的滑行方向。本课题的主要目标是利用新的三维多尺度建模环境和专门设计的实验相结合的模拟来研究M. xanthus群体的基本协调事件，这对于了解数百万细菌在真实环境中如何发挥作用至关重要。具体来说，我们将研究细胞的柔韧性、细胞外多糖的黏度、黏液的黏附性和方向逆转在解决碰撞、增加排列和优化群体速度方面的作用，在突变菌株（A+S-）和（A -S+）和野生型（A+S+）的群体中。预测性模拟将产生新的关于黄原菌群的生物学假设，因为在计算机上进行“实验”的能力仍然难以（或不可能）在物理上进行。这项工作的一个关键方面将是比较在计算机上得到的预测与实验观察。对M. xanthus社会互动的研究将提供一个机会，以获得对生物如何辨别，处理和响应当地环境中存在的化学，物理和生物线索的生物反应的基本见解。

DESCRIPTION (provided by applicant): One of the most important emerging behaviors in biology is swarm formation. Many species of bacteria swarm, including species found in diverse soil and water environments such as Bacillus subtilis, Serratia liquefaciens, Proteus mirabilis, Pseudomonas aeruginosa, and Myxococcus xanthus. These and other swarming bacteria span the gamut of utility and range from innocuous carbon-cycle organisms to harmful pathogens. Swarming is observed in cells that are propelled by rotating flagella, by the secretion of slime, and by retracting type IV pili. Bacteria move on substrates and change their local environment in a way that improves cellular physical interaction and optimizes swarming. M. xanthus, a rod-shaped, Gram negative myxobacterium is able to glide on surfaces using two genetically independent yet cooperative A and S motility engines. These bacteria produce slime and move on slime tracks produced by other members of the colony. Remarkably, these bacteria also regularly reverse their gliding directions. The main goal of this proposal is to combine simulations using new three-dimensional multiscale modeling environment and specifically designed experiments to study basic coordination events of M. xanthus swarming, which is essential to understanding how millions of bacteria function in real environments. Specifically, we will study the role of flexibility of cells, viscosity of extracellular polysaccharide, slime adhesivity and directional reversals in resolving collisions, increasing alignment and optimizing swarming rate during swarming of mutant strains (A+S-) and ( A-S+) and wild type (A+S+) of M. xanthus. Predictive simulations will yield new biological hypotheses about M. Xanthus swarming because of the ability to conduct "experiments" in silico that are yet difficult (or impossible) to perform physically. A key aspect of this work will be to compare predictions obtained in silico with experimental observations. Study of the M. xanthus social interactions will provide an opportunity to gain fundamental insight into the biological response to how organisms discern, process, and respond to the chemical, physical, and biological cues present in their local environment.