title: Boundaries steer the contraction of active gels.
abstract: Cells set up contractile actin arrays to drive various shape changes and to exert forces to their environment. To understand their assembly process, we present here a reconstituted contractile system, comprising F-actin and myosin II filaments, where we can control the local activation of myosin by light. By stimulating different symmetries, we show that the force balancing at the boundaries determine the shape changes as well as the dynamics of the global contraction. Spatially anisotropic attachment of initially isotropic networks leads to a self-organization of highly aligned contractile fibres, being reminiscent of the order formation in muscles or stress fibres. The observed shape changes and dynamics are fully recovered by a minimal physical model.
authors.affiliation: Department of Physics, Cellular Biophysics E27, Technical University of Munich, Garching D-85748, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Schuppler
authors.affiliation: Department of Physics, Cellular Biophysics E27, Technical University of Munich, Garching D-85748, Germany.
authors.forename: Felix C
authors.initials: FC
authors.lastname: Keber
authors.affiliation: Department of Materials, Polymer Physics, ETH Zurich, Zurich CH-8093, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Kröger
authors.affiliation: Department of Physics, Cellular Biophysics E27, Technical University of Munich, Garching D-85748, Germany.
authors.forename: Andreas R
authors.initials: AR
authors.lastname: Bausch
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology* / Q000528:radiation effects; D000199:Actins / Q000378:metabolism / Q000502:physiology*; D000205:Actomyosin / Q000378:metabolism / Q000502:physiology*; D000465:Algorithms; D000818:Animals; D005782:Gels; D008027:Light; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology; D009218:Myosins / Q000378:metabolism / Q000502:physiology*; D011817:Rabbits
chemical_list: D000199:Actins; D005782:Gels; D000205:Actomyosin; D009218:Myosins