Dresden 2014 – scientific programme

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BP: Fachverband Biologische Physik

BP 7: Posters: Cell adhesion, mechanics and migration

BP 7.47: Poster

Monday, March 31, 2014, 17:30–19:30, P3

Non-Equilibrium Cell Mechanics Probed with a Feedback-Controlled Dual Optical Trap — •Florian Schlosser, Florian Rehfeldt, and Christoph F. Schmidt — Drittes Physikalisches Institut - Biophysik, Georg-August Universität Göttingen, Göttingen

Cellular processes not only respond to biochemical, but also to mechanical stimuli. Cells sense the mechanical properties of their surroundings and can adapt to the mechanical properties of their micro-environment. Acto-myosin structures are key players in the generation of contractile forces that cells use to probe the outside world.

We study the contributions of acto-myosin fibers to the force produced by a cell. We attach fibronectin-coated beads to opposite sides of suspended 3T3 fibroblast cells and analyze the correlated motions of the two beads. Using a combination of active and passive microrheology, we could identify the non-equilibrium fluctuations and simultaneously probe the viscoelastic properties of the cell. With a feedback-controlled force clamp we were able to measure the cellular response to a constant external force.

Here, we present data on contractile forces and elastic properties of the cell. Biochemical perturbation experiments demonstrate the key role of myosin motors for contractile force generation. Using the optical trap in force-feedback mode (e.g. force clamp) allowed us to analyze the cellular fluctuations at different levels of pre-stress. Combination with confocal scanning microscopy allows us to directly image the fluorescently tagged actin distribution during the trapping experiments and correlate structure and function.