Biology subjects

Rappel, W.-J.

Publications and source records attributed to Rappel, W.-J..

2 recordsLinked to original sources

bioRxiv2019

Plasticity of cell migration resulting from mechanochemical coupling

Eukaryotic cells can migrate using different modes, ranging from amoeboid-like, during which actin filled protrusions come and go, to keratocyte-like, characterized by a stable morphology and persistent motion. How cells can switch between these modes is still not well understood but waves of signaling events on the cell cortex are thought to play an important role in these transitions. Here we present a simple two component biochemical reaction-diffusion model based on relaxation oscillators and couple this to a model for the mechanics of cell deformations. Different migration modes, including amoeboid-like and keratocyte-like, naturally emerge through phase transitions determined by interactions between biochemical traveling waves, cell mechanics and morphology. The model predictions are explicitly verified by systematically reducing the protrusive force of the actin network in experiments using wild-type Dictyostelium discoideum cells. Our results indicate the importance of coupling signaling events to cell mechanics and morphology and may be applicable in a wide variety of cell motility systems.

biophysics↗

bioRxiv2019

Flower-like patterns in multi-species biofilms

Diverse interactions among species within bacterial biofilms often lead to intricate spatiotemporal dynamics. The spatial structure of biofilms can determine growth and survival of different species, but the mechanisms driving formation of this structure are not fully understood. Here, we describe the emergence of complex structures in a biofilm grown from mixtures of motile and non-motile bacterial species on a soft agar surface. Time-lapse imaging shows that non-motile bacteria "hitchhike" on the motile bacteria as the latter migrate outward. The non-motile bacteria accumulate at the boundary of the colony and trigger an instability that leaves behind striking flower-like patterns. The mechanism of the front instability governing this pattern formation is elucidated by a mathematical model for the frictional motion of the colony interface, with friction depending on the local concentration of the nonmotile species along the interface. A more elaborate two-dimensional phase-field model that explicitly accounts for the interplay between growth, mechanical stress from the motile species, and friction provided by the non-motile species, fully reproduces the observed flower-like patterns.

microbiology↗