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Growth dynamics of actin filament networks

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Cells often migrate in response to external signals, including chemical and mechanical signals. Thereby the interfacial growth of filamentous actin polymer networks plays an important role. For example, cell crawling on a two-dimensional substrate involves the formation of a cytoplasmic membrane protrusion pointing in the direction of motion. Thereby, the necessary force for extending the membrane is provided by the polymerization of actin, a process far from chemical equilibrium, which converts chemical into mechanical energy. The same molecular machinery is also responsible for the propulsion of so called biomimetic objects, such as spherical beads, vesicles, or droplets.

On short time scale actin networks behave as nonlinear elastic solids. This raises the question of the coupling mechanism between growth dynamics and deformations (or stresses) in the network, a property which is often either neglected or included via ad hoc assumptions, which do not necessarily respect all symmetries in the system. Our objective is therefore to derive macroscopic evolution equations of actin networks combining a macroscopic constitutive law for its mechanical behavior and the actin polymerization kinetics in a rigorous way. This general formulation can be adapted to diverse situations relevant for actin dynamics, which can be studied during a Master internship or which could serve as a starting point for a Ph.D. thesis.

No special prerequisites are required, except for a strong interest in theoretical and interdisciplinary questions.

contact : Karin John (