dorsal/arxiv
View SchemaMechano-chemical coupling in growth process of actin gels and a symmetry breaking instability
| Authors | Ken Sekimoto, Jacques Prost, Frank Julicher, Hakim Boukellal, Anne Bernheim-Grosswasser |
|---|---|
| Categories | |
| ArXiv ID | physics/0307077 |
| URL | https://arxiv.org/abs/physics/0307077 |
Abstract
It has been observed experimentally that the actin gel grown from spherical beads coated with polymerization enzymes spontaneously breaks the symmetry of its spherical shape, and yields a ``comet'' pushing the bead forward. We propose a mechano-chemical coupling mechanism for the initialization of this symmetry breaking. Key assumptions are that the dissociation of the gel takes place mostly in the region of the external surface, and that the rates of the dissociation depends on the tensile stress in the gel. We analyze a simplified two-dimensional model with a circular substrate. Our analysis shows that the symmetric steady state is always unstable against the inhomogeneous modulation of the thickness of the gel layer, for any radius of the circular substrate. We argue that this model represents the essential feature of the three-dimensional systems for a certain range of characteristic lengths of the modulation. The characteristic time of the symmetry breaking process in our model depends linearly on the radius of curvature of the substrate surface, which is consistent with experimental results, using spherical latex beads as substrate. Our analysis of the symmetry breaking phenomenon demonstrates aspects of mechano-chemical couplings that should be working in vivo as well as in vitro.
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"abstract": "It has been observed experimentally that the actin gel grown from spherical\nbeads coated with polymerization enzymes spontaneously breaks the symmetry of\nits spherical shape, and yields a ``comet\u0027\u0027 pushing the bead forward. We\npropose a mechano-chemical coupling mechanism for the initialization of this\nsymmetry breaking. Key assumptions are that the dissociation of the gel takes\nplace mostly in the region of the external surface, and that the rates of the\ndissociation depends on the tensile stress in the gel. We analyze a simplified\ntwo-dimensional model with a circular substrate. Our analysis shows that the\nsymmetric steady state is always unstable against the inhomogeneous modulation\nof the thickness of the gel layer, for any radius of the circular substrate. We\nargue that this model represents the essential feature of the three-dimensional\nsystems for a certain range of characteristic lengths of the modulation. The\ncharacteristic time of the symmetry breaking process in our model depends\nlinearly on the radius of curvature of the substrate surface, which is\nconsistent with experimental results, using spherical latex beads as substrate.\nOur analysis of the symmetry breaking phenomenon demonstrates aspects of\nmechano-chemical couplings that should be working in vivo as well as in vitro.",
"arxiv_id": "physics/0307077",
"authors": [
"Ken Sekimoto",
"Jacques Prost",
"Frank Julicher",
"Hakim Boukellal",
"Anne Bernheim-Grosswasser"
],
"categories": [
"physics.bio-ph",
"physics.chem-ph"
],
"title": "Mechano-chemical coupling in growth process of actin gels and a symmetry breaking instability",
"url": "https://arxiv.org/abs/physics/0307077"
},
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