Single-Cell Biophysics: Measurement, Modulation, and Modeling

Single-Cell Biophysics: Measurement, Modulation, and Modeling

Poster Abstracts

55-POS Board 28 Analysis of Single Particle Tracking Data under Heterogeneous Conditions Martin Lindén 1 , Vladimir Curic 1,2 , Elias Amselem 1 , Johan Elf 1 . 1 Uppsala University, Uppsala, Sweden, 2 IMINT Image Intelligence, Uppsala., Sweden. Recent advances in single particle tracking (SPT) microscopy make it possible to obtain tens of thousands of macromolecular trajectories from living cells in just a few minutes. Since molecules typically change their movement properties upon interactions, these trajectories contain information about locations and rates of intracellular reactions. Effectively extracting this information is a statistical challenge, and an active research area. A particular difficulty is heterogeneity in the data across and within nominally identical experiments. Unaccounted for, such variations can induce analysis artifacts and present a serious hurdle for quantitative analysis for large data sets. For example, the localization errors of single emitters may vary due to out-of- focus motion, drift, motion blur, fluorophore intensity fluctuations, heterogeneous background, or gradual photo-bleaching of the background or labeled molecule. To deal with such variations, we have extended localization methods to estimate both position and localization uncertainty from images of single emitters. We find that an uncertainty estimate based on the Bayesian posterior density and constrained by simple microscope properties performs well in a wide range of conditions relevant for live cell imaging. Furthermore, this additional information about localization uncertainty can be incorporated into trajectory analysis methods to improve diffusion constant estimates, detection of binding events, and the localization of single emitters. Here, we will discuss ongoing progress in this area, including attempts to estimate the number of diffusive states in multi-state SPT experiments.

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