  The motility of adherent eukaryotic cells is driven by the dynamics of the
actin cytoskeleton. Despite the common force-generating actin machinery,
different cell types often show diverse modes of locomotion that differ in
their shape dynamics, speed, and persistence of motion. Recently, experiments
in Dictyostelium discoideum have revealed that different motility modes can be
induced in this model organism, depending on genetic modifications,
developmental conditions, and synthetic changes of intracellular signaling.
Here, we report experimental evidence that in a mutated D. discoideum cell line
with increased Ras activity, switches between two distinct migratory modes, the
amoeboid and fan-shaped type of locomotion, can even spontaneously occur within
the same cell. We observed and characterized repeated and reversible switchings
between the two modes of locomotion, suggesting that they are distinct
behavioral traits that coexist within the same cell. We adapted an established
phenomenological motility model that combines a reaction-diffusion system for
the intracellular dynamics with a dynamic phase field to account for our
experimental findings.
