Regensburg 2007 – scientific programme
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BP: Fachverband Biologische Physik
BP 26: Poster Session II
BP 26.46: Poster
Thursday, March 29, 2007, 17:00–19:30, Poster B
Actin Propelled Colloids: Motility Analysis, Orientation, and Force Measurements — Stephan Schmidt1, •Maarten Biesheuvel1, Richard Weinkamer1, Emmanuèle Helfer2, Marie-France Carlier2, and Andreas Fery1 — 1Max Planck Institut für Kolloid- und Grenzflächenforschung, Wissenschaftspark Golm, 14424 Potsdam, Germany — 2Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, 91198 Gif-sur-Yvette, France
The ability to generate forces and move actively is one of the key features of micro-organisms and nature has found various pathways to accomplish it. Many of these processes are driven by actin polymerization were actin filaments grow against the membrane, generating a force and pushing it forward. The molecular scale origin of force generation is still matter of debate. We use a simplified in vitro assay composed of purified proteins on artificial colloidal objects. For example, we can couple actin based motion with coated silica particles or even hollow microcapsules. We have analyzed the motion of colloids, focusing on the curvature of the trajectories of the particles. A simple model explains the curvature distribution and the scaling with velocity. Furthermore, we were able to direct the self propelling colloidal objects along paths on micro-structured substrates. In principle this particle confining setup renders AFM force measurements on the freely moving particles possible. An alternative setup is used for force measurements on the growing actin network directly. Here the growing actin network is clamped between an AFM cantilever and the substrate.