Berlin 2018 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 27: Cell Mechanics II
BP 27.4: Vortrag
Donnerstag, 15. März 2018, 10:30–10:45, H 1028
Poroelastic two-phase model for moving droplets of Physarum polycephalum with free boundaries — •Dirk Alexander Kulawiak1, Jakob Löber3, Markus Bär2, and Harald Engel1 — 1Institut für Theoretische Physik, TU Berlin, Berlin, Germany — 2Physikalisch-Technische Bundesanstalt, Berlin, Germany — 3Max-Planck-Institut für Physik komplexer Systeme, Dresden Germany
Motivated by recent experiments, we model the flow-driven amoeboid motility that is exhibited by protoplasmic droplets of Physarum. Here, a feedback loop between a chemical regulator, active mechanical deformations, and induced flows give rise to spatio-temporal contraction patterns that result in directed motion. Our model describes the droplet's cytoskeleton as an active viscoelastic solid phase that is permeated by a passive viscous fluid representing the cytosol. The active tension in the solid phase depends on the concentration of a regulating agent that is advected by the fluid phase. Previously, it was shown that under rigid boundary conditions that impose a fixed shape, this model reproduces a large variety of mechano-chemical patterns such as antiphase oscillations and rotating spirals. This in line with experimental observations of contraction patterns in these droplets. Here, we present an approach that includes free boundary conditions, nonlinear friction between droplet and substrate and a nonlinear reaction kinetic for the regulator to model the movement of these droplets. We find deformations of the droplet boundary as well as oscillatory changes in the droplets position with a net motion in each cycle.