Regensburg 2019 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 3: Bioimaging and biospectroscopy I

BP 3.3: Vortrag

Montag, 1. April 2019, 10:00–10:15, H11

Non-equilibrium dynamics of endoplasmic reticulum structures — •Konstantin Speckner, Lorenz Stadler, and Matthias Weiss — Experimental Physics 1, University of Bayreuth, Germany

Intracellular transport frequently shows anomalous characteristics, i.e. a sublinear increase of the mean-square displacement in time. Using single-particle tracking we have studied the subdiffusion of cellular organelle structures, with a particular emphasis on the impact of non-equilibrium driving forces imposed by cytoskeletal elements. In particular, we have analyzed the dynamics of tubular junctions in the endoplasmic reticulum (ER) network [1] and of ER membrane domains (ER exit sites, ERES) [2]. Our results demonstrate that both, ER junctions and ERES show a distinct subdiffusion with an anti-correlation of successive steps, reminiscent of fractional Brownian motion. Disrupting the microtubule cytoskeleton significantly altered the subdiffusive characteristics of both entities, highlighting that even subdiffusion in living cells is an actively driven process. While the motion pattern of ER junctions was seen to be directly dependent on the presence of microtubules, ERES were only indirectly affected. Our experimental data indicate that ER junctions move like monomer units of (semi)flexible polymers with the overall dynamics of the ER network being governed by fractons. ERES rather are mobile domains that perform a quasi-one-dimensional random walk on the shivering backbone of ER tubules.

[1] K. Speckner et al., Phys. Rev. E 98, 012406 (2018).

[2] L. Stadler et al., Biophys. J. 115(8), 1552 (2018).