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Disordered Systems: From Physics to Biology

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Front. Phys. | doi: 10.3389/fphy.2018.00131

Intracellular mass density increase is accompanying but not sufficient for stiffening and growth arrest of yeast cells

 Shada Abuhattum1, 2,  Kyoohyun Kim1,  Titus Franzmann3, Anne Eßlinger3, Daniel Midtvedt4, Raimund Schlüßler1, Stephanie Möllmert1,  Hui-Shun Kuan5, Simon Alberti3,  Vasily Zaburdaev5 and  Jochen Guck1*
  • 1Technische Universität Dresden, Germany
  • 2JPK Instruments (Germany), Germany
  • 3Max-Planck-Institut für Molekulare Zellbiologie und Genetik, Germany
  • 4Chalmers University of Technology, Sweden
  • 5Max-Planck-Institut für Physik komplexer Systeme, Germany

Many organisms, including yeast cells, bacteria, nematodes and tardigrades, endure harsh environmental conditions, such as nutrient scarcity, or lack of water and energy for a remarkably long time. The rescue programs that these organisms launch upon encountering these adverse conditions include reprogramming their metabolism in order to enter a quiescent or dormant state in a controlled fashion. Reprogramming coincides with changes in the macromolecular architecture and changes in the physical and mechanical properties of the cells. However, the cellular mechanisms underlying the physical-mechanical changes remain enigmatic. Here, we induce metabolic arrest of yeast cells by lowering their intracellular pH. We then determine the differences in the intracellular mass density and stiffness of active and metabolically arrested cells using optical diffraction tomography and atomic force microscopy. We show that an increased intracellular mass density is associated with an increase in stiffness when the growth of yeast is arrested. However, increasing the intracellular mass density alone is not sufficient for maintenance of the growth-arrested state in yeast cells. Our data suggest that the cytoplasm of metabolically arrested yeast displays characteristics of a solid. Our findings constitute a bridge between the mechanical behavior of the cytoplasm and the physical and chemical mechanisms of metabolically arrested cells with the ultimate aim of understanding dormant organisms.

Keywords: yeast, stiffness, Atomic force microscopy - AFM, Optical diffraction tomography - ODT, Liquid-to-solid phase transition, Refractive index

Received: 01 Aug 2018; Accepted: 30 Oct 2018.

Edited by:

Giancarlo Ruocco, Istituto italiano di Tecnologia (IIT), Center for Life NanoScience, Italy

Reviewed by:

Barbara Cortese, Istituto di Nanotecnologia (NANOTEC), Italy
Giovanni Cappello, Centre national de la recherche scientifique (CNRS), France  

Copyright: © 2018 Abuhattum, Kim, Franzmann, Eßlinger, Midtvedt, Schlüßler, Möllmert, Kuan, Alberti, Zaburdaev and Guck. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Jochen Guck, Technische Universität Dresden, Dresden, Germany, jochen.guck@tu-dresden.de