SKM 2023 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 25: Cell Mechanics II
BP 25.7: Vortrag
Donnerstag, 30. März 2023, 16:45–17:00, BAR Schö
Chromatin and Nucleocytoplasmic Transport Control the Nuclear Biophysical Properties during Assembly in Egg Extracts — •Omar Muñoz1,2, Abin Biswas1,4, Kyoohyun Kim1,3, Simone Reber4, Jochen Guck1,3, and Vasily Zaburdaev1,2 — 1Max-Planck-Zentrum für Physik und Medizin — 2Department of Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg — 3Max Planck Institute for the Science of Light — 4IRI Life Sciences, Humboldt-Universität zu Berlin
Biophysical properties of the cell nucleus are important for various cellular processes from migration to stress responses, but largely are still not well understood. One fundamental example is the mass density: we observed that the nuclear mass density consistently displays a lower value than its cytoplasmic counterpart for a wide range of species, which is surprising given that it contains the highly compacted genetic material. To understand the mechanisms behind this, we measured volume and mass density of growing nuclei reconstituted in Xenopus egg extracts. Our results identified nucleocytoplasmic transport and chromatin as the main determinants for the dry mass and volume of then nucleus, and suggest a coupling of chromatin with nucleocytoplasmic transport. We propose a theoretical model informed by experiments, which incorporates active transport of proteins and balance of colloid osmotic pressure and an entropic polymer pressure exerted by chromatin. With only a few adjustable parameters, our model can fully describe the nuclear volume and mass dynamics as observed in the experiments.