Dynamics of frontal extension of an amoeboid cell

Abstract

The acellular slime mould Physarum polycephalum forms giant plasmodia that consist of an apical zone, which is succeeded by a vast network of veins where protoplasm is periodically transported back and forth. The apical zone is formed by a dense layer of viscoelastic cell material, whose leading edge is characterized by the development of undulations, which are called fingers. The dynamics of finger formation and evolution was studied. The front is characterized by alternating events of front advancement and stagnation, which are reflected in the development of the fingers. Therefore, the dynamics of the front was divided into two distinct, periodically alternating regimes. The dispersion relations, i.e., the growth rates of fingers of different wavelengths, observed in these two regimes were found to be symmetric, except for the sign of the growth rates. Furthermore, finger splitting occurred once the fingers reached a critical curvature. Our findings are discussed in terms of the intracellular dynamics of this slime mould.

Oscillations and uniaxial mechanochemical waves in a model of an active poroelastic medium: Application to deformation patterns in protoplasmic droplets of Physarum polycephalum

“…of extended macroplasmodia in Physarum [65]. Similarly to the protoplasmic droplets the apical zone of extended plasmodia consists of a porous medium.…”

Adaptive behaviour and learning in slime moulds: the role of oscillations

“…These contractions produce a pressure gradient that pushes the endoplasm towards the cell periphery, where the veins vanish and the endoplasm can flow freely. Local cytoskeletal reorganization and local alteration of the actin–myosin cortex lead to the formation of pseudopods or fan-shaped leading fronts which extend and retract in synchrony with the shuttle streaming of the endoplasm [30,36,37]. Based on internal and external cues, P. polycephalum can adapt and alter its shape, size and motion.…”

Fluid flows shaping organism morphology

“…Plasmodia that exceed ∼ 500 µm form a full network structure often including multiple migration fronts. Over the peristaltic cycle a front location advances and retracts asymmetrically leading to net advancement at long time scales [52]. As networks grow they move faster [24].…”