Amoeboid motion in confined geometry

TL;DR

This study explores how confinement influences amoeboid swimmer behavior, revealing that confinement can alter swimming nature, speed, and trajectory stability through combined numerical and theoretical methods.

Contribution

It demonstrates that confinement can change an amoeboid swimmer's nature and stability, providing new insights into cell motility in confined environments.

Findings

Swimmer's pusher or puller nature can be altered by confinement.

Swimming speed initially increases then decreases with confinement.

Swimmer trajectories become unstable with lateral excursions.

Abstract

Many eukaryotic cells undergo frequent shape changes (described as amoeboid motion) that enable them to move forward. We investigate the effect of confinement on a minimal model of amoeboid swimmer. Complex pictures emerge: (i) The swimmer's nature (i.e., either pusher or puller) can be modified by confinement, thus suggesting that this is not an intrinsic property of the swimmer. This swimming nature transition stems from intricate internal degrees of freedom of membrane deformation. (ii) The swimming speed might increase with increasing confinement before decreasing again for stronger confinements. (iii) A straight amoeoboid swimmer's trajectory in the channel can become unstable, and ample lateral excursions of the swimmer prevail. This happens for both pusher- and puller-type swimmers. For weak confinement, these excursions are symmetric, while they become asymmetric at stronger confinement, whereby the swimmer is located closer to one of the two walls. In this study, we combine numerical and theoretical analyses.