Regensburg 2013 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 24: Posters: Physics of Cells
BP 24.13: Poster
Mittwoch, 13. März 2013, 17:30–19:30, Poster C
The actin cytoskeleton of chemotactic amoebae operates close to the onset of oscillations — Christian Westendorf1, •Jose Negrete Jr1, Albert Bae1, Rabea Sandmann1, Eberhard Bodenschatz1,2, and Carsten Beta1,3 — 1Max Planck Institute for Dynamics and Self-Organization (MPIDS), Göttingen — 2Laboratory of Atomic and Solid-State Physics, Cornell University, USA — 3Institute of Physics and Astronomy, University of Potsdam
The rapid reorganization of the actin cytoskeleton in response to external stimuli is an essential property of many motile eukaryotic cells. Here, we report evidence that the actin machinery of chemotactic Dictyostelium cells operates close to an oscillatory instability. When averaging the actin response of many cells to a short pulse of the chemoattractant cAMP, we observed a transient accumulation of cortical actin reminiscent of a damped oscillation. At the single-cell level, however, the response dynamics ranged from strongly to weakly damped oscillations. Furthermore, in a small subpopulation, we observed self-sustained oscillations in the cortical F-actin concentration. To substantiate that an oscillatory mechanism governs the actin dynamics in these cells, we systematically exposed a large number of cells to periodic pulse trains of different frequencies. We propose a model based on a time-delay in the regulatory network of the actin system. The model was quantitatively tested with experiments performed with cells that express GFP-tagged fusion in proteins that enhance the disassembly of actin filaments and thus allow us to estimate the delay time in the regulatory feedback loop.