Cellular Sensing Governs the Stability of Chemotactic Fronts

TL;DR

This paper presents a theoretical analysis showing that the stability of chemotactic fronts in cell populations depends on the cells' ability to sense chemical gradients, with implications for understanding biological pattern formation and migration stability.

Contribution

It introduces a model linking sensing limitations to front stability and predicts chemotactic fingering due to sensing constraints, supported by experimental data on E. coli.

Findings

Limited sensing leads to chemotactic fingering.

Cells' sensory machinery may have evolved for stability.

Sensing-induced stability principle applies to various directed migrations.

Abstract

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.