Regensburg 2013 – scientific programme

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BP: Fachverband Biologische Physik

BP 24: Posters: Physics of Cells

BP 24.22: Poster

Wednesday, March 13, 2013, 17:30–19:30, Poster C

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

It is accepted knowledge that cells sense the mechanical properties of their surroundings, and that many internal cellular processes not only respond to biochemical, but also to mechanical stimuli. Cells generate contractile forces themselves to probe and to adapt to the mechanical properties of their micro-environment. Key players in the generation of contractile forces are acto-myosin structures, such as stress fibers. We aim at elucidating the contributions of acto-myosin fibers to the total force produced by suspending a cell in an idealized geometry between two optical traps. In our setup we attach fibronectin-coated beads to opposite sides of a suspended 3T3 fibroblast cell. We analyze the correlated motion of the two beads at high bandwidth and with pN-resolution by laser interferometry. Using a combination of active and passive microrheology, we can dissect the non-equilibrium fluctuations and simultaneously probe the viscoelastic properties of the cell. Here we present data on contractile forces and elastic properties of the cell. The amount of force fluctuations transmitted to the outside depends on trap stiffness. Biochemical perturbation experiments interfering with the acto-myosin cytoskeleton or microtubules demonstrate the key role of myosin motors for contractile force generation. We used different bead sizes to determine the effect of cell-bead attachment and also tested the cellular response at different temperatures.