We present a model which couples the membrane with protrusive forces of actin polymerization and contractile molecular motors, such as myosin. The at is activated by freely diffusing proteins that have spontaneous curvature. Molecular motors are recruited to polymerizing filaments, from constant reservoir, produce force. All variables treated in linear limit. Our results show for convex myosin activity gives rise robust transverse waves, similar those observed on different cells.

The role of the coupling between shape membrane-bound filaments and membrane is demonstrated for dynamics FtsZ rings on cylindrical membranes. Filaments with an arc-like spontaneous curvature, a possible added active contractile force, are shown to spontaneously condense into tight rings, associated local inward deformation membrane. long-range membrane-mediated interactions attractive at short ring-ring separations, inducing further coarsening dynamics, whereby smaller merge form larger...

The forces that arise from the actin cytoskeleton play a crucial role in determining cell shape. These include protrusive due to polymerization and adhesion external matrix. We present here theoretical model for cellular shapes resulting feedback between membrane shape acting on membrane, mediated by curvature-sensitive complexes of convex In previous studies we have investigated regimes linear instability where spontaneous formation protrusions is initiated. Here calculate evolution two...

Successful cytokinesis requires proper assembly of the contractile actomyosin ring, its stable positioning on cell surface and constriction. Over years, many key molecular components regulators ring have been elucidated. Here we show that geometry mechanics play a crucial role in uniform constriction ring. Contractile rings assemble spherical end caps fission yeast cells normal morphology or are unstable slip towards poles. On other hand, locally cylindrical portions under same conditions do...

Microrheological studies of phospholipid monolayers, bilayers, and other Langmuir monolayer systems are traditionally performed by observing the thermal fluctuations tracers attached to membrane or interface. Measurements this type obtain surface moduli that orders magnitude different from those obtained using macroscopic active techniques. These large discrepancies can result uncertainties in tracer's coupling local disruption tracer. To avoid such problems, we perform a microrheological...

Dynamin is a protein that plays key role in the transport and recycling of membrane tubes vesicles within living cell. This adsorbs from solution to PIP2-containing membranes, on these it forms curved oligomers condense into tight helical domains uniform radius. The dynamics this process treated here terms linear stability continuum model, whereby membrane-mediated interactions are shown drive spontaneous nucleation condensed dynamin domains. We furthermore show deformation outside induces...

Proliferating animal cells are able to orient their mitotic spindles along interphase cell axis, setting up the axis of division, despite rounding as they enter mitosis. This has previously been attributed molecular memory and, more specifically, maintenance adhesions and retraction fibers in mitosis [1Théry M. Jiménez-Dalmaroni A. Racine V. Bornens Jülicher F. Experimental theoretical study spindle orientation.Nature. 2007; 447: 493-496Crossref PubMed Scopus (320) Google Scholar, 2Fink J....

A non-contact microrheological technique to probe the mechanics of air/water interface is explored. Polystyrene spheres dissolved in water are trapped with an optical tweezer near free surface water, allowing response functions particles be measured as a function distance from interface. These measurements show that at surface, imaginary part increases by approximately 30% Stokes value bulk. As particle moved away via trap, returns bulk value. The method tested comparing rigid wall theory...

Hair cells of the inner ear contain an active amplifier that allows them to detect extremely weak signals. As one manifestations process, spontaneous oscillations arise in fluid immersed hair bundles vitro preparations selected auditory and vestibular organs. We measure phase-locking dynamics oscillatory exposed low-amplitude sinusoidal signals, a transition can be described by saddle-node bifurcation on invariant circle. The is characterized occurrence phase slips, at rate dependent...

Microrheology relies on tracking the thermal or driven motion of microscopic particles in a soft material. It is well suited to study materials that have no three-dimensional realization, which makes them difficult using macroscopic rheometer. For this reason, microrheology becoming an important rheological probe Langmuir monolayers and membranes. Interfacial microrheology, however, has been reconcile quantitatively with more traditional approaches. We suggest uncertainties accounting for...

The inner ear constitutes a remarkably sensitive mechanical detector. This detection occurs in noisy and highly viscous environment, as the sensory cells—the hair cells—are immersed fluid-filled compartment operate at room or higher temperatures. We model active motility of cell bundles vestibular system with Adler equation, which describes phase degree freedom bundle motion. explore both analytically numerically response to external signals, presence white noise. theoretical predicts that...

Propagating waves on the surface of cells, over many micrometers, involve active forces. We investigate here mechanical excitation such when membrane is perturbed by an external oscillatory force. The perturbation may trigger propagation away from force application. This scheme then suggested as a method to probe properties excitable medium cell, and learn about mechanisms that drive wave propagation. apply these ideas specific model cellular waves, demonstrating how response system depends...

We consider two mechanisms that can lead to an inhomogeneous distribution of components in a multicomponent lipid bilayer: macroscopic phase separation and the formation modulated phases. A simple model encompasses both displays diagram also includes structured fluid, microemulsion. Identifying rafts with inhomogeneities this we see how are related occurrence or phases other systems, focus our attention on specific differences between them.

We study the dynamics and patterning of polar contractile filaments on surface a cylindrical cell using active hydrodynamic equations that incorporate couplings between curvature filament orientation. Cables rings spontaneously emerge as steady state configurations cylinder, can be stationary or moving, helical tilted segments moving along trajectories. observe phase transitions in patterns upon changing diameter motor-driven activity make several testable predictions. Our results are...

We compute bond-breaking dynamics of a semiflexible filament under loading, and compare to observed driven particle motion in biopolymer networks.

In this letter we describe how membrane inclusions that have a spontaneous curvature, will be convected on the due to propagation of waves. We calculate Stokes drift such particles and effect their overall density field. solve analytically for uniform sinusoidal wave in absence diffusion, using simulations more realistic case decaying waves with diffusion. latter provide some good analytic approximations. A variety propagate over significant proportion cell surface exists living cells,...