Self-organization of microtubules and motors drive large-scale intracellular flows in cells

Cytoplasmic streaming is essential for transporting and mixing nutrients, proteins, and organelles within large plant and animal cells. The large ~200um Drosophila oocyte has recently gained attention for experimental and theoretical studies of this phenomenon. We present a quantitative study of streaming in Drosophila oocytes that combines PIV of 3D time-lapse movies, with biophysical modeling and simulation. We observe a diverse family of 3D vortical flows across different oocytes, which differ in position and orientation, and which last tens of minutes. We show that a model of cytoskeletal activity at the periphery, organized by its interaction with interior fluid, explains the observed streaming structures. The emerging picture sheds light on a class of intracellular flows in large cells and highlights the wealth of questions at the interface of geometry, active matter, and basic biology.