Collective dynamics of microtubule-based 3D active fluids from gliding assay

Flows in passive fluids require temperature or pressure gradients. The gradients are not required for active fluids due to their capability of consuming local fuel to generate kinetic energy. The energy generated at a microscopic scale cascades up, resulting in macroscopic flows. However, the relation between microscopic and macroscopic dynamics remains unclear. Here we approach the problem with molecular motor-driven, microtubule (MT)-based 3D active fluids. We measure their flow mean speed at a millimeter scale, as a function of temperature, comparing with MT 2D gliding assay at a micron scale. We found that despite both systems differed in scales and dimensionality, they responded to temperature similarly. Moreover, such similarity was invariant under the change of motor processivity. Our work demonstrates collective dynamics of microtubule-based active fluids depends primarily on motor’s energy transducing rates, rather than motor’s dynamic details. Our finding expands flexibility in designing 3D active fluids using miscellaneous types of motors, as well as paves the path to outlining principles of self-organization of active fluids.