Correlative all-optical quantification of mass density and mechanics of sub-cellular compartments with fluorescence specificity
- Technische Universität Dresden, Germany
- Max Planck Institute for the Science of Light, Germany
- University of Rostock, Germany
Abstract
Quantitative measurements of physical parameters become increasingly important for understanding biological processes. Brillouin microscopy (BM) has recently emerged as one technique providing the 3D distribution of viscoelastic properties inside biological samples - so far relying on the implicit assumption that refractive index (RI) and density can be neglected. Here, we present a novel method (FOB microscopy) combining BM with optical diffraction tomography and epi-fluorescence imaging for explicitly measuring the Brillouin shift, RI and absolute density with specificity to fluorescently labeled structures. We show that neglecting the RI and density might lead to erroneous conclusions. Investigating the nucleoplasm of wild-type HeLa cells, we find that it has lower density but higher longitudinal modulus than the cytoplasm. Thus, the longitudinal modulus is not merely sensitive to the water content of the sample - a postulate vividly discussed in the field. We demonstrate the further utility of FOB on various biological systems including adipocytes and intracellular membraneless compartments. FOB microscopy can provide unexpected scientific discoveries and shed quantitative light on processes such as phase separation and transition inside living cells.
Data availability
The data sets generated during and/or analyzed during the current study are available from figshare under the following link: https://doi.org/10.6084/m9.figshare.c.5347778
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Combined fluorescence, optical diffraction tomography and Brillouin microscopyFigshare repository, doi:10.6084/m9.figshare.c.5347778.
Article and author information
Author details
Funding
Deutsche Forschungsgemeinschaft (419138906)
- Simon Alberti
- Jochen Guck
Volkswagen Foundation (92847)
- Simon Alberti
- Jochen Guck
Alexander von Humboldt-Stiftung
- Jochen Guck
NOMIS Stiftung
- Andreas Hermann
Hermann und Lilly Schilling-Stiftung
- Andreas Hermann
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Rohit V Pappu, Washington University in St Louis, United States
Version history
- Preprint posted: October 30, 2020 (view preprint)
- Received: March 17, 2021
- Accepted: January 8, 2022
- Accepted Manuscript published: January 10, 2022 (version 1)
- Version of Record published: February 4, 2022 (version 2)
Copyright
© 2022, Schlüßler et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Correlative all-optical quantification of mass density and mechanics of sub-cellular compartments with fluorescence specificity
eLife 11:e68490.
https://doi.org/10.7554/eLife.68490
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