Actin dynamics in oscillatory Dictyostelium cells

During the first funding period, the groups of Beta and Bodenschatz (project A09) showed that the actin cytoskeleton of motile amoeboid cells operates close to an oscillatory instability (Westendorf et al., PNAS (2013) 110:3853-3858). Together with PI Tarantola (project A08) they now focused on oscillatory Dictyostelium cells in the immediate vicinity of the Hopf bifurcation point and investigated the role of noise in these cells from a fundamental point of view. In particular, due to the presence of noise, the periodic activity in the actin system that drives the formation of pseudopods is extended beyond the bifurcation point. The approach rests on a generic nonlinear oscillator model that characterizes the dynamics of a large class of noisy systems close to an oscillatory instability (Negrete at al. Phys. Rev. Lett. (2016) 117:148102).



Intracellular actin dynamics. Left: multicolor confocal recording of a Dictyostelium cell forming a pseudopod (white arrow) (LimE-mRFP and Coronin-GFP). Right: oscillatory time trace of two fluorescent cytoskeletal markers expressed in the cell shown on the right hand side.