Berlin 2015 – scientific programme

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BP: Fachverband Biologische Physik

BP 33: Cell adhesion, mechanics and migration I (joint BP/CPP)

BP 33.8: Talk

Wednesday, March 18, 2015, 12:00–12:15, H 1058

Force fluctuations in three-dimensional suspended fibroblasts — •Florian Schlosser, Christoph F. Schmidt, and Florian Rehfeldt — Drittes Physikalisches Institut - Biophysik, Georg-August-Universität Göttingen

Cells are sensitive to mechanical cues from their environment and at the same time generate and transmit forces to probe and to adapt to their surroundings. Key players in the generation of contractile forces are acto-myosin structures. To test forces and elasticity of cells not attached to a substrate, we used a dual optical trap to suspend 3T3 fibroblasts between two fibronectin-coated beads. We analyzed the correlated motions of the beads with high bandwidth. A combination of active and passive microrheology allowed us to measure the non-equilibrium force fluctuations as well as the elastic properties of the cell. We found that cortical forces deform the cell from its round shape in the frequency regime from 0.1 to 10 Hz. Biochemical perturbation experiments using blebbistatin for myosin inhibition and nocodazole for microtubule depolymerization show that cell stiffness and cortical force fluctuations highly depend on acto-myosin activity but not on microtubules. Serum-starvation also largely reduced the fluctuation amplitude. A force-clamp allowed us to observe cells under defined constant forces. Combining our optical trap with a confocal microscope allowed us to image the three-dimensional actin distribution of Life-Act transfected cells during the force measurements.

Schlosser, Rehfeldt, Schmidt, Phil. Trans. R. Soc. B 20140028, 2014