Sliusarenko Oleksii, Zusman David R, Oster George
Department of Physics, University of California, Berkeley, CA 94720, USA.
J Bacteriol. 2007 Jan;189(2):611-9. doi: 10.1128/JB.01206-06. Epub 2006 Nov 10.
When starved, Myxococcus xanthus cells assemble themselves into aggregates of about 10(5) cells that grow into complex structures called fruiting bodies, where they later sporulate. Here we present new observations on the velocities of the cells, their orientations, and reversal rates during the early stages of fruiting body formation. Most strikingly, we find that during aggregation, cell velocities slow dramatically and cells orient themselves in parallel inside the aggregates, while later cell orientations are circumferential to the periphery. The slowing of cell velocity, rather than changes in reversal frequency, can account for the accumulation of cells into aggregates. These observations are mimicked by a continuous agent-based computational model that reproduces the early stages of fruiting body formation. We also show, both experimentally and computationally, how changes in reversal frequency controlled by the Frz system mutants affect the shape of these early fruiting bodies.
饥饿时，黄色黏球菌细胞会聚集形成约10⁵个细胞的聚集体，这些聚集体会生长成称为子实体的复杂结构，它们随后会在其中形成孢子。在这里，我们展示了关于子实体形成早期阶段细胞速度、方向和反转率的新观察结果。最引人注目的是，我们发现在聚集过程中，细胞速度急剧减慢，并且细胞在聚集体内部平行排列，而后来细胞的方向是围绕聚集体周边呈圆周状。细胞速度的减慢，而非反转频率的变化，可以解释细胞聚集形成聚集体的现象。基于连续主体的计算模型模拟了这些观察结果，该模型再现了子实体形成的早期阶段。我们还通过实验和计算表明，由Frz系统突变体控制的反转频率变化如何影响这些早期子实体的形状。
