Self-organized intracellular twisters

Life in complex systems, such as cities and organisms, comes to a standstill when global coordination of mass, energy and information flows is disrupted. Global coordination is no less important in single cells, especially in large oocytes and newly formed embryos, which commonly use fast fluid flows for dynamic reorganization of their cytoplasm. These cytoplasmic streaming flows have been proposed to spontaneously arise from hydrodynamic interactions among cortically anchored microtubules loaded with cargo-carrying molecular motors. Here, we combine modelling and simulation with live imaging to investigate such flows in the Drosophila oocyte. Using a fast, accurate and scalable numerical approach to investigate fluid–structure interactions of thousands of flexible fibres, we demonstrate the robust emergence and evolution of cell-spanning vortices—or twisters—in three-dimensional cellular geometries. These twister flows, dominated by a near-rigid-body rotation with secondary toroidal components, reproduce the variety of experimental observations. In cells, these flows are probably involved in rapid mixing and transport of ooplasmic components.