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AKB: Biologische Physik

AKB 5: Cell Motility II

AKB 5.4: Vortrag

Montag, 27. März 2006, 15:00–15:15, ZEU 255

Investigation and Manipulation of Membrane Dynamics by an Optical Tweezers Technique — •Michael Goegler, Timo Betz, and Josef Käs — Institute for Soft Matter Physics, University of Leipzig, Linnéstrasse 5, 04103 Leipzig, Germany

Cell migration is essential in various cellular activities, such as morphogenesis, wound healing, and metastasis. In these events, protrusion of the cell membrane at the leading edge is the fundamental step, and the mechanism driving this movement is likely associated with the elongation of polymerizing actin filaments or with molecular motors, such as myosin. To elucidate the mechanism of protrusion, we use a new laser based technique to study membrane motion with high spatial and temporal resolution in the nanometer and microseconds range, respectively. A diffraction limited laser spot is positioned at the leading edge of a cell and the forward scattered light is imaged on a quadrant diode detector which serves as a position sensitive device. We investigated the membrane motion at the leading edge of different cell types, such as fibroblasts and erythrocytes. The new technique has the potential to reveal relative contributions to the membrane fluctuations based on its frequency spectrum, and to measure physical properties, such as the bending rigidity of the membrane. By increasing the laser intensity we were able to exert a significant force on the cell’s leading edge that is strong enough to deform the cell and change its membrane dynamics. We present the capabilities of the technique and show that it provides the opportunity to measure rheological properties of cells.