Princeton Center for Theoretical Science, Princeton University, Princeton, New Jersey 08544, USA.
Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA.
Phys Rev Lett. 2022 Apr 8;128(14):148101. doi: 10.1103/PhysRevLett.128.148101.
In contexts ranging from embryonic development to bacterial ecology, cell populations migrate chemotactically along self-generated chemical gradients, often forming a propagating front. Here, we theoretically show that the stability of such chemotactic fronts to morphological perturbations is determined by limitations in the ability of individual cells to sense and thereby respond to the chemical gradient. Specifically, cells at bulging parts of a front are exposed to a smaller gradient, which slows them down and promotes stability, but they also respond more strongly to the gradient, which speeds them up and promotes instability. We predict that this competition leads to chemotactic fingering when sensing is limited at too low chemical concentrations. Guided by this finding and by experimental data on E. coli chemotaxis, we suggest that the cells' sensory machinery might have evolved to avoid these limitations and ensure stable front propagation. Finally, as sensing of any stimuli is necessarily limited in living and active matter in general, the principle of sensing-induced stability may operate in other types of directed migration such as durotaxis, electrotaxis, and phototaxis.
在从胚胎发育到细菌生态学的各种情况下，细胞群体沿着自身产生的化学梯度进行化学趋性迁移，通常形成一个传播前沿。在这里，我们从理论上表明，这种趋化性前沿对形态扰动的稳定性取决于单个细胞感知和响应化学梯度的能力的限制。具体来说，处于前沿凸起部分的细胞暴露在较小的梯度中，这会使它们的速度减慢并促进稳定性，但它们对梯度的反应也更强，这会使它们的速度加快并促进不稳定性。我们预测，当在太低的化学浓度下限制感测时，这种竞争会导致趋化指状现象。受这一发现以及大肠杆菌趋化性的实验数据的指导，我们认为细胞的感觉机制可能已经进化到避免这些限制并确保稳定的前沿传播。最后，由于对任何刺激的感知在一般的活体和活性物质中必然是有限的，因此感知诱导稳定性的原则可能在其他类型的定向迁移中起作用，例如趋硬性、趋电性和趋光性。
