How the nuclear size dynamically scales with the cellular size during osmotic shock treatments remains controversial. We develop a dynamic model by incorporating the typical interactions between polydisperse biomolecules and the mechanical elasticity of the cytoplasm and nucleoplasm to investigate this long-standing critical issue. We find the nontrivial phenomenon that the nuclear-to-cellular volume ratio can vary nonmonotonically with time, instead of maintaining a constant as usually known, under the osmotic shocks. Combining simulations and analytical argument, we validly account for this nonmonotonic dynamic behavior, and identify its essential regulatory mechanism to be the collaboration of the excluded volume interactions between the polydisperse biomolecules and the spatial constraint from the nuclear envelope on the macromolecule diffusions. Our results agree well with the published experiments for cellular and nuclear size controls of the protoplasts. Our model offers energetic insight in characterizing biology-associated dynamic processes such as macromolecular crowding, and biophase separation occurring in cytoplasm and nucleoplasm.

• Received 31 July 2023
• Accepted 28 November 2023

DOI:https://doi.org/10.1103/PhysRevResearch.6.L012014

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Published by the American Physical Society