arXiv subjects

D. Biron

Publications and source records attributed to D. Biron.

3 recordsLinked to original sources

arXiv2010

Molecular Model of the Contractile Ring

We present a model for the actin contractile ring of adherent animal cells. The model suggests that the actin concentration within the ring and consequently the power that the ring exerts both increase during contraction. We demonstrate the crucial role of actin polymerization and depolymerization throughout cytokinesis, and the dominance of viscous dissipation in the dynamics. The physical origin of two phases in cytokinesis dynamics ("biphasic cytokinesis") follows from a limitation on the actin density. The model is consistent with a wide range of measurements of the midzone of dividing animal cells.

physics.bio-ph↗

arXiv2003

Cytokinesis: the initial linear phase crosses over to a multiplicity of non-linear endings

We investigate the final stage of cytokinesis in two types of amoeba, pointing out the existence of biphasic furrow contraction. The first phase is characterized by a constant contraction rate, is better studied, and seems universal to a large extent. The second phase is more diverse. In Dictyostelium discoideum the transition involves a change in the rate of contraction, and occurs when the width of the cleavage furrow is comparable to the height of the cell. In Entamoeba invadens the contractile ring carries the cell through the first phase, but cannot complete the second stage of cytokinesis. As a result, a cooperative mechanism has evolved in that organism, where a neighboring amoeba performs directed motion towards the dividing cell, and physically causes separation by means of extending a pseudopod. We expand here on a previous report of this novel chemotactic signaling mechanism.

q-bio.CB↗

arXiv2000

Slow Coarsening in a Class of Driven Systems

The coarsening process in a class of driven systems is studied. These systems have previously been shown to exhibit phase separation and slow coarsening in one dimension. We consider generalizations of this class of models to higher dimensions. In particular we study a system of three types of particles that diffuse under local conserving dynamics in two dimensions. Arguments and numerical studies are presented indicating that the coarsening process in any number of dimensions is logarithmically slow in time. A key feature of this behavior is that the interfaces separating the various growing domains are smooth (well approximated by a Fermi function). This implies that the coarsening mechanism in one dimension is readily extendible to higher dimensions.

cond-mat.stat-mech↗