Regensburg 2013 – scientific programme

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BP: Fachverband Biologische Physik

BP 1: Cell migration

BP 1.5: Talk

Monday, March 11, 2013, 10:45–11:00, H43

Spatiotemporal dynamics of self-organized waves in electro-fused amoeboid cells. — •Matthias Gerhardt, Michael Walz, and Carsten Beta — Institut für Physik und Astronomie, Karl-Liebknecht-Strasse 24/25, 14476 Potsdam, Germany

We investigated the intracellular dynamics of PIP3 and F-Actin in electro-fused Dictyostelium discoideum cells by confocal laser scanning microscopy, using the markers PHCRAC-GFP and LimE-mRFP, respectively. The obtained fusion products were approximately 10-100 times larger than native Dictyostelium cells. In the substrate-attached cortex, they exhibit self-organized actin waves, similar to non-fused cells. However, due to the increased size of the fused cells, we can now observe the dynamics of the actin waves for the first time in much larger spatial domains. The wave patterns show many characteristic features that are well known from excitable reaction-diffusion systems. The dynamics is characterized by expanding circular and elliptic waves as well as rotating spirals. If such waves collide, they annihilate each other. The distribution of the fluorescent markers indicate that F-actin is concentrated at the leading front of the wave followed by a PIP3 enriched zone containing only little F-actin. Using a custom written software, the recorded wave patterns were fitted either by ellipses or spiral-functions to determine the cell displacement, the wave velocity, and the curvature of individual waves for further analysis. Furthermore, our data suggest an important role of the F-actin waves in cell motility, an observation that can be accounted for in terms of a simple mechanical model.