Abstract

Gels of fibrous biopolymers are ubiquitous within cells and their rigidity is crucial for their function [1]. Our current understanding of their elastic response is usually understood as an interplay between the bending and stretching of their filaments [2]. This point of view however fails when applied to the weakly coordinated branched actin networks found throughout the cell [3, 4]. Through experiments and theory, we show that transient contacts between entangled filaments govern their adaptive mechanics. Additional contacts may get locked in during network growth, setting the final properties of the system [5]. These properties could be key to understanding how moving cells dynamically adapt their cytoskeleton to their environment.

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[2] C. P Broedersz, X Mao, T C Lubensky, and F. C MacKintosh. Criticality and isostaticity in fibre networks. Nature Physics, 7(12):983, 2011.

[3] P Bauer, J Tavacoli, T Pujol, J Planade, J Heuvingh, and O Du Roure. A new method to measure mechanics and dynamic assembly of branched actin networks. Scientific reports, 7(1):15688, 2017.

[4] A Allard, M Bouzid, T Betz, C Simon, M Abou-Ghali, J Lemiere, F Valentino, J Manzi, F Brochard-Wyart, K Guevorkian, et al. Actin modulates shape and mechanics of tubular membranes. Science advances, 6(17):eaaz3050, 2020.

[5] M Bouzid, C Valencia Gallardo, L Koehler, G Foffi, J Heuvingh, O du Roure, and M Lenz. Elasticity from entanglements in branched actin. In preparation.