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

描述(申请人提供)：生物学中最重要的新兴行为之一是群体形成。许多种类的细菌群，包括在不同的土壤和水环境中发现的种类，如枯草杆菌、液化沙雷氏菌、奇异变形杆菌、铜绿假单胞菌和黄色粘球菌。这些细菌和其他成群的细菌跨越了各种用途，范围从无害的碳循环生物到有害的病原体。在由旋转的鞭毛、粘液的分泌和IV型菌毛的收缩推动的细胞中可以观察到群集性。细菌在底物上移动，并以一种改善细胞物理相互作用和优化集群的方式改变它们的局部环境。黄色分枝杆菌是一种杆状的革兰氏阴性粘细菌，它能够使用两个遗传独立但又相互合作的A和S运动引擎在表面滑行。这些细菌产生粘液，并在殖民地其他成员产生的粘液轨道上移动。值得注意的是，这些细菌还经常改变它们的滑行方向。这一建议的主要目标是将使用新的三维多尺度建模环境的模拟与专门设计的实验相结合，以研究黄色微囊藻集群的基本协调事件，这对于了解数百万细菌在真实环境中的功能是必不可少的。具体地说，我们将研究细胞的灵活性、胞外多糖的粘度、粘液粘附性和定向逆转在解决黄瓜突变株(A+S-)、(A-S+)和野生型(A+S+)的群聚过程中解决碰撞、提高比对和优化群化率方面的作用。预测性模拟将产生关于黄花杉成群的新的生物学假说，因为它能够在硅胶中进行物理上仍难以(或不可能)进行的“实验”。这项工作的一个关键方面将是将在Silico中获得的预测与实验观测进行比较。对黄花草的社会相互作用的研究将提供一个机会，从根本上洞察生物体如何识别、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学反应。

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.