Ref HAL: hal-02374362_v1
Ref Arxiv: 1812.06484
DOI: 10.1039/c9sm01172b
WoS: WOS:000493519700010
Ref. & Cit.: NASA ADS
Exporter : BibTex | endNote
1 Citation
Résumé:

Cells and tissues have the remarkable ability to actively generate the forces required to change theirshape. This active mechanical behavior is largely mediated by the actin cytoskeleton, a crosslinkednetwork of actin filaments that is contracted by myosin motors. Experiments and active gel theorieshave established that the length scale over which gel contraction occurs is governed by a balancebetween molecular motor activity and crosslink density. By contrast, the dynamics that govern thecontractile activity of the cytoskeleton remain poorly understood. Here we investigate the microscopicdynamics of reconstituted actin–myosin networks using simultaneous real-space video microscopy andFourier-space dynamic light scattering. Light scattering reveals different regimes of microscopicdynamics as a function of sample age. We uncover two dynamical precursors that precede macroscopicgel contraction. One is characterized by a progressive acceleration of stress-induced rearrangements,while the other consists of sudden, heterogeneous rearrangements. Intriguingly, our findings suggest aqualitative analogy between self-driven rupture and collapse of active gels and the delayed rupture ofpassive gels observed in earlier studies of colloidal gels under external loads.