论文标题
拓扑缺陷促进粘膜球菌的层形成
Topological defects promote layer formation in Myxococcus xanthus colonies
论文作者
论文摘要
叶thus的土壤细菌粘膜菌属生活在密集的群中，这些群体响应环境变化而形成动态的三维模式，例如饥饿期间类似液滴的水果体。这些多细胞结构的开发始于在不理会的过程中细胞层的顺序形成。使用共聚焦三维成像，我们发现运动杆形的叶thus细胞在每一层中密集堆积并对齐，形成一个活跃的列液液晶体。在整个人群中，细胞对齐几乎是完美的，除了携带半数拓扑电荷的点缺陷。我们观察到，新细胞层优先形成+1/2缺陷的位置，而孔优先在-1/2缺陷处打开。为了解释这些发现，我们将细菌菌落建模为具有各向异性摩擦的大量活性列液。与我们的实验测量结果一致，该模型预测细胞向+1/2缺陷的流入，以及-1/2缺陷的细胞流出。我们的结果表明，细胞运动和机械细胞 - 细胞相互作用足以促进拓扑缺陷处的细胞层形成，从而在Xanthus菌落中播种成果。
The soil bacterium Myxococcus xanthus lives in densely packed groups that form dynamic three-dimensional patterns in response to environmental changes, such as droplet-like fruiting bodies during starvation. The development of these multicellular structures begins with the sequential formation of cell layers in a process that is poorly understood. Using confocal three-dimensional imaging, we find that motile rod-shaped M. xanthus cells are densely packed and aligned in each layer, forming an active nematic liquid crystal. Cell alignment is nearly perfect throughout the population except at point defects that carry half-integer topological charge. We observe that new cell layers preferentially form at the position of +1/2 defects, whereas holes preferentially open at -1/2 defects. To explain these findings, we model the bacterial colony as an extensile active nematic fluid with anisotropic friction. In agreement with our experimental measurements, this model predicts an influx of cells toward +1/2 defects, and an outflux of cells from -1/2 defects. Our results suggest that cell motility and mechanical cell-cell interactions are sufficient to promote the formation of cell layers at topological defects, thereby seeding fruiting bodies in colonies of M. xanthus.
