菌群趋化迁移的有序空间结构形成机制研究

生物自组织形成有序结构对生命活动有重要的作用。在前期发表的工作中，申请人通过调控细菌个体的趋化运动能力表型，发现不同表型在菌群趋化迁移过程中呈有序空间排布，而该有序结构使得差异化的个体实现了协调统一的群体行为。然而，对于该有序结构的形成机制尚不明确，即细菌是如何通过个体的随机游动行为自发地确定其在群体中的相对位置？通过单细胞追踪实验，我们发现细菌个体在群体迁移中呈现出均值回归的随机运动。因此，我们提出：在菌群迁移时，细菌消耗吸引物形成浓度梯度场；在该梯度场作用下，不同个体将围绕与其趋化运动能力相对应的中心做均值回归的随机运动；该中心呈空间单调分布，使得菌群形成宏观有序的空间结构。本项目拟基于人工构建的菌群趋化迁移系统，通过定量实验结合理论模型，量化细菌的个体行为与排序策略，从而阐明菌群迁移行为有序结构的形成机制及其生物学意义。本项目的实施将为人工构建生物自组织系统提供新思路和新理论。

Ordered structure plays an important role in living systems. Our previous study showed the emergence of ordered structure in bacterial chemotactic migration with cells of different chemotaxis abilities. This ordered structure enable bacterial population to coordinate diverse individuals to form collective migration. However, the mechanism how this ordered structure emerges is still not clear. In another words, how individual cells that performs a run-and-tumble random motions find their relative positions in the migratory group is in a myth. Our preliminary experiments showed that bacteria can perform mean-reversion random walks. Therefore, we proposed the following hypothesis: bacteria consume chemo-attractant to form a gradient during collective migration; this gradient drives bacteria as a force field to enable the bacteria to perform mean-reversion random motions around the centers respect to their chemotactic abilities; the centers of each phenotypes with different chemotactic abilities are monotonically aligned; therefore, ordered structure emerges. In this project, we will study the bacterial behavior and ordering strategy, to understand the forming mechanism of ordered structure in bacterial collective migration and its biological meaning. This study will bring new insights and theories to synthetic self-organized biological systems.