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BP: Fachverband Biologische Physik

BP 13: Cell Mechanics I

BP 13.3: Talk

Tuesday, March 17, 2020, 10:15–10:30, SCH A251

Intracellular activity and mechanics in dividing epithelial cells — •Sebastian Hurst, Bart E. Vos, Matthias Brandt, Till Münker, and Timo Betz — Institute of Cell Biology, ZMBE, Münster, Germany

While there is a good understanding of cortical mechanics during cell division, surprisingly little is known about the intracellular mechanics and activity during this fundamental process. Nevertheless, intracellular mechanics have a tremendous impact on both chromosome and organelle distribution. Furthermore, an increase in intracellular activity would help to distribute organelles before cytokinesis. This so-called active diffusion is achieved by random, undirected fluctuations, e.g. generated through motor protein activity.

To quantify the intracellular mechanics, we perform active and passive microrheology measurements using optical tweezers on phagocytosed exogenous particles inside dividing MDCK cells. We obtain the frequency-dependent complex shear modulus and the effective energy, which quantifies the activity in units of thermal energy. We observe global differences between interphase and mitosis. Focusing on mitosis, current results suggest that the cells become more fluid-like in pro- and metaphase, while they become more solid-like towards the end of mitosis. Compared to interphase, the effective energy drops in mitosis, whereas it does not change drastically during cell division. Moreover, experiments with cells in mitotic arrest show that the activity is mostly myosin driven. This data supports a published model connecting mechanics to intracellular activity.