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BP: Fachverband Biologische Physik

BP 11: Posters: Statistical Physics in Biological Systems (joint with DY)

BP 11.12: Poster

Montag, 11. März 2013, 17:30–19:30, Poster B2

3D-Tracking of phagosomal transport by molecular motors through the cytoskeleton — •Martin Glasstetter and Alexander Rohrbach — Lab for Bio- and Nano-Photonics, University of Freiburg, Germany

Molecular motors play a crucial role in cellular dynamics. Not only are they responsible for cell motility but also for muscle contraction or the transport of organelles. They pace along cytoskeleton filaments by a kind of active, directed diffusion. Typically, several motors are coupled via the cargos they transport through the interior of cells and thus enhance transport efficiency. In order to observe the directed motion of molecular motors we induce the phagocytosis of a 1µm sized polystyrene bead by bringing it close to the membrane of a macrophage with an optical trap. After the bead is engulfed it starts being transported through the cell from the cell periphery to the interior. Sometimes observable movements of the phagosome are discontinuous and reveal discrete steps. Depending of step sizes and rates these traces are an indicator for the transport of the bead by myosin motors along actin filaments or by kinesin motors along microtubules respectively. The transport of the bead is tracked interferometrically with nm precision in 3D and with a sample rate up to 1MHz. Additionally, we want to observe the local structure of the cytoskeleton surrounding the bead with the aid of coherent light scattering of a second weak laser. This allows in principle to reveal the interaction of the local reorganizing cytoskeleton and the phagosome transported by molecular motors. First results from measurements and computer simulations are presented.