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Structure formation in active networks


Structure formation and constant reorganization of the actin cytoskeleton are key requirements for the function of living cells. Here we show that a minimal reconstituted system consisting of actin filaments, crosslinking molecules and molecular-motor filaments exhibits a generic mechanism of structure formation, characterized by a broad distribution of cluster sizes. We demonstrate that the growth of the structures depends on the intricate balance between crosslinker-induced stabilization and simultaneous destabilization by molecular motors, a mechanism analogous to nucleation and growth in passive systems. We also show that the intricate interplay between force generation, coarsening and connectivity is responsible for the highly dynamic process of structure formation in this heterogeneous active gel, and that these competing mechanisms result in anomalous transport, reminiscent of intracellular dynamics.

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Figure 1: Effect of κ on actin/fascin/myosin network structure.
Figure 2: Dynamics of actin/fascin/myosin networks.
Figure 3: Time evolution of the cluster-size distribution.
Figure 4: Dynamics of small, medium and large clusters.
Figure 5: Dependence of the mean run length on the cluster size.
Figure 6: Mean square displacement.
Figure 7: Dynamics and coarsening behaviour in the simulations.


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We gratefully acknowledge technical support by M. Rusp, G. Chmel and K. Vogt. We gratefully acknowledge the financial support of the DFG in the framework of the SFB 863, and partial support in the framework of the German Excellence Initiative by the ‘Nanosystems Initiative Munich’ and the ‘Institute of Advanced Studies’ (TUM-IAS). S.K. and V.S. thank the ‘International Graduate School for Science and Engineering’. V.S. acknowledges support from the Elite Network of Bavaria by the graduate programme CompInt.

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S.K. and A.R.B. designed experiments, carried out and analysed experiments. V.S., S.K. and A.R.B. conceived, carried out and analysed the simulations and wrote the paper.

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Correspondence to Andreas R. Bausch.

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The authors declare no competing financial interests.

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Köhler, S., Schaller, V. & Bausch, A. Structure formation in active networks. Nature Mater 10, 462–468 (2011).

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