title: Disentangling Random Motion and Flow in a Complex Medium.
abstract: We describe a technique for deconvolving the stochastic motion of particles from large-scale fluid flow in a dynamic environment such as that found in living cells. The method leverages the separation of timescales to subtract out the persistent component of motion from single-particle trajectories. The mean-squared displacement of the resulting trajectories is rescaled so as to enable robust extraction of the diffusion coefficient and subdiffusive scaling exponent of the stochastic motion. We demonstrate the applicability of the method for characterizing both diffusive and fractional Brownian motion overlaid by flow and analytically calculate the accuracy of the method in different parameter regimes. This technique is employed to analyze the motion of lysosomes in motile neutrophil-like cells, showing that the cytoplasm of these cells behaves as a viscous fluid at the timescales examined.
authors: Department of Biochemistry, Stanford University School of Medicine, Stanford, California.
authors: Elena F
authors: EF
authors: Koslover
authors: Department of Biochemistry, Stanford University School of Medicine, Stanford, California.
authors: Caleb K
authors: CK
authors: Chan
authors: Department of Biochemistry, Stanford University School of Medicine, Stanford, California; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California; Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California. Electronic address: theriot@stanford.edu.
authors: Julie A
authors: JA
authors: Theriot
mesh_terms: D001692:Biological Transport; D002460:Cell Line; D003593:Cytoplasm / Q000378:metabolism; D004058:Diffusion; D006801:Humans; D008247:Lysosomes / Q000378:metabolism; D044085:Microfluidics / Q000379:methods*; D008962:Models, Theoretical; D009038:Motion; D013269:Stochastic Processes