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DY: Fachverband Dynamik und Statistische Physik

DY 17: Physics of Physarum polycephalum and Other Slime Molds - Joint Focus Session (BP/DY) organized by Hans-Günther Döbereiner

DY 17.5: Vortrag

Dienstag, 21. März 2017, 10:45–11:00, SCH A251

Hydrodynamic Mechanism of Information Processing in Physarum polycephalum — •Christina Oettmeier, Jonghyun Lee, and Hans-Günther Döbereiner — Institut für Biophysik, Universität Bremen

P. polycephalum exhibits rich spatiotemporal oscillatory behaviour. The organism’s size spans orders of magnitude, from meter-sized networks to micrometer-sized amoebae. All morphotypes show actomyosin-based contraction-relaxation cycles resulting in protoplasmic streaming. When a food source is encountered, oscillations at the stimulated site increase in frequency. If repellents are encountered, the local oscillation frequency decreases [1]. This either leads to movement towards the attractant or away from the repellent. We study hydrodynamic information processing in amoeboid locomotion. Autonomous foraging units (mesoplasmodia) maintain their shape over hours while moving in straight trajectories at constant mean speed. Oscillations in the back of the mesoplasmodium cause endoplasm flows through the internal vein system and expand the frontal membrane. Frequencies at the back are higher than those at the front due to filtering. We use the electronic-hydraulic analogy to investigate this case of information processing. A vein segment can be described as a flexible tube, possessing a fluidic resistance (R) and fluidic capacitance (C). The electronic equivalent is a passive RC low pass filter. We use SPICE to simulate vein behaviour. Light- and EM data of mesoplasmodia and other morphotypes provide geometrical and elastic parameters.

[1] Durham, A.C.H. & Ridgway, E.B. (1976), J.Cell Biol. 69, 218-223