Structures of Flow in an Active Network

Quantifying the spatial structure of flow in actin filament networks

Mechanical stresses generated by the actomyosin cytoskeleton can drive large-scale structural rearrangements and shape changes at cellular or multicellular scales.

At the University of Chicago MRSEC, Gardel and Dinner explore the mechanics of cytoskeletal materials in a controlled fashion by reconstituting actin filament networks in vitro with varying connectivity. The team developed novel measures to quantify the spatial structure of flow and deformation modes in these networks. The image shows fluorescent actin (grayscale) network containing the molecular motor myosin II which drives internal motions.  Trajectories of individual actin bundles are shown  in  the  rainbow  trajectories,  indicating short range correlation in motion, which is not observed across the sample. Analyses reveal microscopic features of flow in cytoskeletal materials and show that mechanically rigid networks can preserve ordered structures by transmitting uniaxial stresses whereas networks of compressible filaments contract into isotropic structures via cooperative buckling events and cannot maintain structural alignment.