title: Cytoplasmic RNA-Protein Particles Exhibit Non-Gaussian Subdiffusive Behavior.
abstract: The cellular cytoplasm is a complex, heterogeneous environment (both spatially and temporally) that exhibits viscoelastic behavior. To further develop our quantitative insight into cellular transport, we analyze data sets of mRNA molecules fluorescently labeled with MS2-GFP tracked in real time in live Escherichia coli and Saccharomyces cerevisiae cells. As shown previously, these RNA-protein particles exhibit subdiffusive behavior that is viscoelastic in its origin. Examining the ensemble of particle displacements reveals a Laplace distribution at all observed timescales rather than the Gaussian distribution predicted by the central limit theorem. This ensemble non-Gaussian behavior is caused by a combination of an exponential distribution in the time-averaged diffusivities and non-Gaussian behavior of individual trajectories. We show that the non-Gaussian behavior is a consequence of significant heterogeneity between trajectories and dynamic heterogeneity along single trajectories. Informed by theory and simulation, our work provides an in-depth analysis of the complex diffusive behavior of RNA-protein particles in live cells.
authors.affiliation: Department of Chemical Engineering, Stanford University, Stanford, California.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Lampo
authors.affiliation: Department of Physics, Washington University, Seattle, Washington.
authors.forename: Stella
authors.initials: S
authors.lastname: Stylianidou
authors.affiliation: Department of Chemistry, Stanford University, Stanford, California.
authors.forename: Mikael P
authors.initials: MP
authors.lastname: Backlund
authors.affiliation: Department of Physics, Washington University, Seattle, Washington; Department of Bioengineering, Washington University, Seattle, Washington; Department of Microbiology, Washington University, Seattle, Washington.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Wiggins
authors.affiliation: Department of Chemical Engineering, Stanford University, Stanford, California; Department of Applied Physics, Stanford University, Stanford, California; Department of Materials Science, Stanford University, Stanford, California; Biophysics Program, Stanford University, Stanford, California. Electronic address: ajspakow@stanford.edu.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Spakowitz
mesh_terms: D003593:Cytoplasm / Q000378:metabolism*; D004058:Diffusion; D004926:Escherichia coli / Q000166:cytology; D008954:Models, Biological; D009068:Movement; D012329:RNA, Bacterial / Q000378:metabolism*; D012331:RNA, Fungal / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology
chemical_list: D012329:RNA, Bacterial; D012331:RNA, Fungal; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins