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BP: Fachverband Biologische Physik

BP 36: Statistical Physics of Biological Systems IV (joint session BP/DY)

BP 36.5: Talk

Friday, March 13, 2026, 10:45–11:00, BAR/SCHÖ

Anisotropic (sub)diffusion of organelles in living cells — •Aranyak Sarkar, Pooja Yadav, and Matthias Weiss — Experimental Physics I, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth

Eukaryotic cells are neatly organized into distinct, membrane-enclosed compartments (’organelles’) with specific duties. A prominent example are peroxisomes, which feature vesicle-like shapes with radii 0.1−1 µm that are dispersed across the cytoplasm. Using time-lapse fluorescence microscopy, we have tracked the motion of individual peroxisomes over extended periods. Analysis of the experimental data revealed two distinct modes of motion: a prevailing (sub)diffusive motion and a quite rare super-diffusive characteristics that is associated with motor-driven transport along microtubules. Focussing on the seemingly unremarkable subset of (sub)diffusive trajectories, we have found a significant anisotropy in the motion that persisted even when microtubules were disrupted. In particular, diffusive steps along the cells’ long axis were seen to be favored over steps in the perpendicular direction, indicating an anisotropic materials characteristic of the cytoplasm. Using a simple model, we were able to capture and explain the observed features of the anisotropic diffusion of organelles.

Keywords: Peroxisomes; single-particle tracking; anisotropic diffusion; cytoplasmic mechanics; subdiffusive motion