Berlin 2012 – scientific programme

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BP: Fachverband Biologische Physik

BP 23: Cytoskeletal Filaments

BP 23.5: Talk

Thursday, March 29, 2012, 16:15–16:30, H 1028

Evolution of actin networks and bundles in cell-sized confinements — •Siddharth Deshpande and Thomas Pfohl — Department of Chemistry, University of Basel, Switzerland

Actin microfilaments, intermediate filaments and microtubules form the cytoskeleton of a cell along with hundreds of associated proteins. A bottom up in vitro approach suits very well to address such a complex system. We study the spatiotemporal evolution of actin network in quasi-2D cell-sized compartments, termed microchambers using a microfluidic system. The solution composition inside the microchambers can be tuned in a controlled manner by changing the composition of the controlling channel to which they are attached. Thus it is a diffusion limited open system.

Atto488 labeled actin monomers along with time-lapse fluorescence microscopy allow us to visualize the formation and evolution of actin networks and actin bundles under different geometric constraints. At higher concentrations of actin (> 1mg/mL) and divalent counterions (Mg²⁺), stable networks of actin bundles without any cross-linking proteins are obtained and are further analyzed for distribution of link lengths and orientations, connectivity distribution of nodes, etc. The effect of different concentrations of divalent cations (Ca²⁺ and Mg²⁺) on the network formation is studied and further compared with networks obtained using actin associated proteins like α-actinin.