Dresden 2009 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 22: Transport Processes and Cellular Trafficking
BP 22.6: Vortrag
Donnerstag, 26. März 2009, 16:00–16:15, ZEU 260
Elucidating the random process behind crowding-induced subdiffusion — •Marcel Hellmann1,2, Dieter W. Heermann2, and Matthias Weiss1 — 1German Cancer Research Center, Cellular Biophysics Group (BIOMS), Im Neuenheimer Feld 280, D-69120 Heidelberg — 2Universität Heidelberg, Institut für Theoretische Physik, Philosophenweg 19, D-69120 Heidelberg
Complex and crowded media are a widespread phenomenon. A prominent example is the cytoplasm of living cells. The presence of filamentous structures and a plethora of embedded macromolecules strongly affect the mobility of tracer particles. Experiments have shown a subdiffusive behavior of tracers with a nonlinear growth of the mean square displacement: ⟨ x2 ⟩ ∼ tα, α ∼ 0.7 (Weiss et al., Biophys. J.; Guigas et al. Biophys J; FEBS Lett.).
Two competing mathematical models have been proposed to rationalize this experimental observation: The continuous time random walk (CTRW) and fractional Brownian motion (fBM). Owing to their distinct propagators (non-Gaussian and Gaussian-like, respectively), these two models make distinct predictions, e.g. concerning the breaking of ergodicity. To explore which of the two models may explain the experimental findings, we have used mesoscopic computer simulations. In particular, we have investigated the diffusion of tracer particles in a crowded environment that mimics the cytoplasm. Our data suggest that crowding-induced subdiffusion relies on (weakly) attractive interactions of the macromolecules.