Migratory behaviour of Physarum polycephalum microplasmodia
Abteilung Biophysik, Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany
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Received: 17 April 2015
Revised: 18 May 2015
Published online: 24 July 2015
The motility of amoeboid cells of the plasmodial slime mould Physarum polycephalum was studied experimentally. Analysis of their trajectories and of their mean square displacements reveal two characteristic types of behaviour that depend on the time interval τ between any pair of points along the trajectory. Whereas free migration of cells is observed for time intervals τ > 300 s, at short time intervals (of up to τ ≈ 100 s) the motility is due to changes in the cell shape induced by the peristaltic pumping of protoplasm though the cell. Freely migrating cells display persistent random motion with very long persistence times of up to ≈ 5500 s. Superdiffusive motion typically lasts for ≈ 18000 s, independently of the intensity of illumination by green light. Whereas symmetric velocity distributions are found for short time intervals τ, the typical velocity distributions from freely migrating cells show an asymmetry, which reflects the long-lasting persistent motions. We observed that high propagation velocities are correlated with both, episodes of straight motion and an elongated cell shape. Finally, the mean squared displacement of trajectories where the cells avoided crossing their own slime trails were compared to those of freely migrating cells.
© EDP Sciences, Springer-Verlag, 2015