Berlin 2008 – scientific programme
Parts | Days | Selection | Search | Downloads | Help
BP: Fachverband Biologische Physik
BP 8: Active Filament Networks
BP 8.5: Talk
Tuesday, February 26, 2008, 11:15–11:30, C 243
Cytoskeleton nanosurgery Part II: Modeling the retraction dynamics of stress fibers after laser cutting — •Achim Besser1, Julien Colombelli2, Holger Kress3, Ernst Stelzer2, and Ulrich Schwarz1 — 1University of Heidelberg, Bioquant, BQ 0013 BIOMS Schwarz, INF 267, D-69120, Heidelberg, Germany — 2European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, D-69117 Heidelberg, Germany — 3Department of Mechanical Engineering, Yale University, New Haven, CT06511, USA
Cellular stress fibers are bundles of actin filaments that are cross-linked by α-actinin and non-muscle myosin II molecular motors. Due to myosin motor activity, stress fibers are under tension and retract over several microns when being cut with a pulsed laser. The time-dependent displacement field along the fiber is recorded with fluorescence microscopy and thus provides quantitative time course data. Here, we present a continuum stress fiber model that takes into account the internal visco-elastic and contractile properties of the fiber as well as visco-elastic interactions with the surrounding cytoplasm. Through detailed comparison of theory and experiment we are able to quantify physical properties of stress fibers: we extract the average contraction length of sarcomeric units, the degree of cross links of the fibers and we find that external friction due to the retraction within the cytosol can be neglected compared to internal friction resulting from relative filament sliding and myosin motor activity.