Regensburg 2010 – scientific programme

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BP: Fachverband Biologische Physik

BP 37: Biomaterials

BP 37.9: Talk

Friday, March 26, 2010, 12:30–12:45, H43

Linker Induced Actin Network Formation under Cell-Sized Confinement — •Florian Huber, Sebastian Ehrig, Carsten Vogt, Dan Strehle, and Josef Käs — Division of Soft Matter Physics, Department of Physics, University of Leipzig, Linnéstr. 5, D-04103 Leipzig, Germany

Cross-linked actin networks are decisively involved in the overall mechanical properties of cells. The networks' architecture ranges from densely packed bundles to networks with high crossing angles and is typically assigned to specific linker proteins. Recently, however, it was found that weak cross-linkers give rise to both extended networks and bundles. We used multivalent ions as model-linkers to study actin filament aggregation in cell-sized geometries. Small droplets filled with actin filaments are sealed by a thin oil film to control droplet evaporation. At a critical concentration of multivalent ions their potential turns attractive. This implies a phase transition from isotropic or nematic f-actin solutions to cross-linked actin networks.

In addition to the well-known bundle formation, we obtained regularly spaced networks of star-like astern patterns. These networks display many features of cellular networks in the actin cortex and may serve as a model system for the cortical actin layer. Moreover, by altering the linker properties it was possible to switch between different network architectures. Observed phase transitions are fast (seconds to few minutes) which is of high interest concerning the known ability of living cells to quickly modify their morphology.