Regensburg 2022 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 12: Poster 2
BP 12.24: Poster
Dienstag, 6. September 2022, 17:30–19:30, P4
Nuclear Volume, Density and Dry Mass are Controled by Chromatin and Nucleocytoplasmic Transport — •Omar Muñoz1,2, Abin Biswas1,3,4, Kyoohyun Kim1,3, Simone Reber4, Vasily Zaburdaev1,2, and Jochen Guck1,3 — 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
The cell nucleus is an organelle responsible for hosting essential processes such as DNA replication and transcription. Many important biophysical properties of the nucleus are not well understood, for example, its density is lower than the density of the cytoplasm despite the nucleus hosting the highly compressed genome. Motivated by this observation, we combined optical diffraction tomography and confocal fluorescence microscopy and measured, in real time, the material properties of nuclei reconstituted in Xenopus egg extract. We found that nuclear growth has two phases: the first one driven by chromatin decondensation and the second one, by nucleocytoplasmic transport and replication. We also developed a simple theoretical model, where nuclear volume is determined by an entropic polymer pressure exerted by chromatin and an osmotic pressure caused by the protein concentration gradient across the nuclear envelope. The good agreement between the model predictions and experimental results supports a view, where chromatin and nucleocytoplasmic transport are essential contributors to the biophysical properties of the nucleus.