Cell motility: A viscous fingering analysis of active gels

Amar, Martine Ben; Manyuhina, O. V.; Napoli, Gaetano

doi:10.1140/epjp/i2011-11019-7

Cited by 11 publications

(5 citation statements)

References 16 publications

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“…[12], it was found that actomyosin fragments do exhibit a viscous-fingering-like morphological instability, but the fundamental question of whether such a model contains the minimal ingredients to initiate and sustain motion remained unsolved. Extensions of this model to include an explicit symmetry-breaking of the dynamic equations to generate motility have also been reported [16]. Here we show that spontaneous symmetry breaking of the circular shape is sufficient to initiate and sustain motion, even in the absence of myosin motors and largescale polarization, when nonlinearities are taken into account.…”

supporting

confidence: 53%

“…However, the mode m ¼ 1 must be exactly marginal, ð1Þ ¼ 0, reflecting the translational invariance of the problem. Explicit symmetry breaking of the equations has been discussed as a possible mechanism to generate motion [16]. Here, we are interested in whether spontaneous symmetry breaking via a morphological instability is by itself sufficient to initiate and sustain motion, a fundamental question that must be addressed at the nonlinear level.…”

mentioning

confidence: 99%

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Spontaneous Motility of Actin Lamellar Fragments

Blanch-Mercader

Casademunt

2013

Phys. Rev. Lett.

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We show that actin lamellar fragments driven solely by polymerization forces at the bounding membrane are generically motile when the circular symmetry is spontaneously broken, with no need of molecular motors or global polarization. We base our study on a nonlinear analysis of a recently introduced minimal model [Callan-Jones et al., Phys. Rev. Lett. 100, 258106 (2008)]. We prove the nonlinear instability of the center of mass and find an exact and simple relation between shape and center-of-mass velocity. A complex subcritical bifurcation scenario into traveling solutions is unfolded, where finite velocities appear through a nonadiabatic mechanism. Examples of traveling solutions and their stability are studied numerically.

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confidence: 53%

mentioning

confidence: 99%

Spontaneous Motility of Actin Lamellar Fragments

Blanch-Mercader

Casademunt

2013

Phys. Rev. Lett.

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“…The latter is continuously supplied by an incoming flux from the third dimension normal to the epithelial layer and uptaken by cell receptors. As shown in [18], the thinness of the moving layer transforms the threedimensional process into a two-dimensional model, where the localized thickness variation at the border contributes to a tension T. In addition, we assume that a strong viscous friction exists between the moving layer and the substrate [19][20][21][22][23], which allows writing a Darcy's law for the average velocity field inside the tissue, while cell-cell interactions and mitosis are transformed into interface boundary conditions in the sharp interface limit. We first present the physical model, then the analytical treatment giving an explicit solution for the circular geometry and a study of its stability.…”

Section: Introductionmentioning

confidence: 99%

Re-epithelialization: advancing epithelium frontier during wound healing

Amar

2014

J. R. Soc. Interface.

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The first function of the skin is to serve as a protective barrier against the environment. Its loss of integrity as a result of injury or illness may lead to a major disability and the first goal of healing is wound closure involving many biological processes for repair and tissue regeneration. In vivo wound healing has four phases, one of them being the migration of the healthy epithelium surrounding the wound in the direction of the injury in order to cover it. Here, we present a theoretical model of the re-epithelialization phase driven by chemotaxis for a circular wound. This model takes into account the diffusion of chemoattractants both in the wound and the neighbouring tissue, the uptake of these molecules by the surface receptors of epithelial cells, the migration of the neighbour epithelium, the tension and proliferation at the wound border. Using a simple Darcy's law for cell migration transforms our biological model into a free-boundary problem, which is analysed in the simplified circular geometry leading to explicit solutions for the closure and making stability analysis possible. It turns out that for realistic wound sizes of the order of centimetres and from experimental data, the re-epithelialization is always an unstable process and the perfect circle cannot be observed, a result confirmed by fully nonlinear simulations and in agreement with experimental observations.

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“…A multicomponent theory based on irreversible thermodynamics is derived in [2,9,10]. The theory seems to be able to make a number of successful predictions, e.g., the onset of spontaneous flow [11,12], motility and spontaneous division of active nematic droplets [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Active nematic gels as active relaxing solids

Turzi

2017

Phys. Rev. E

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I propose a continuum theory for active nematic gels, defined as fluids or suspensions of orientable rodlike objects endowed with active dynamics, that is based on symmetry arguments and compatibility with thermodynamics. The starting point is our recent theory that models (passive) nematic liquid crystals as relaxing nematic elastomers. The interplay between viscoelastic response and active dynamics of the microscopic constituents is naturally taken into account. By contrast with standard theories, activity is not introduced as an additional term of the stress tensor, but it is added as an external remodeling force that competes with the passive relaxation dynamics and drags the system out of equilibrium. In a simple one-dimensional channel geometry, we show that the interaction between nonuniform nematic order and activity results in either a spontaneous flow of particles or a self-organization into subchannels flowing in opposite directions.

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Cell motility: A viscous fingering analysis of active gels

Cited by 11 publications

References 16 publications

Spontaneous Motility of Actin Lamellar Fragments

Spontaneous Motility of Actin Lamellar Fragments

Re-epithelialization: advancing epithelium frontier during wound healing

Active nematic gels as active relaxing solids

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