Berlin 2012 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 27: Posters: Cytoskeletal Filaments
BP 27.12: Poster
Donnerstag, 29. März 2012, 17:30–19:30, Poster A
Vimentin Filaments in Small Configuration Spaces — •Bernd Nöding, Susanne Bauch, and Sarah Köster — Institute for X-Ray Physics and CRC Physics, University of Göttingen, Germany
The eukaryotic cytoskeleton mainly consists of three types of fibrous proteins. While microtubules and microfilaments are highly conserved, intermediate filaments (IFs) vary from one cell type to another. Here, we focus our study on vimentin IFs. Investigations of the mechanical properties of individual filaments are a necessary prerequisite for a better understanding of the mechanics of biopolymer networks and eventually whole cells. The mechanical rigidity of a polymer is characterized by its persistence length Lp. We perform time-resolved measurements of fluorescently labeled filaments in solutions of different viscosities without any interaction with a substrate whatsoever. To this end, we confine the filaments in microchannels of variable widths and heights (∼ µm). The purpose of using the channels is threefold: first, they mimic the crowded environment of the cell. Second, they reduce the configuration space occupied by the filaments, thereby markedly improving statistics. Third, they realize the Odijk confinement regime. We find that IFs behave as ideal worm-like chains. Inclusion of data for microfilaments, which are also confined in the Odijk regime, shows that both filament systems behave according to a single scaling law. Furthermore, we find that fluctuations in perpendicular directions decouple as predicted by the worm-like chain model. For freely fluctuating individual vimentin filaments we determine Lp ∼ 2 µm.