title: Mapping the subcellular mechanical properties of live cells in tissues with fluorescence emission-Brillouin imaging.
abstract: Extracellular matrices (ECMs) are central to the advent of multicellular life, and their mechanical properties are modulated by and impinge on intracellular signaling pathways that regulate vital cellular functions. High spatial-resolution mapping of mechanical properties in live cells is, however, extremely challenging. Thus, our understanding of how signaling pathways process physiological signals to generate appropriate mechanical responses is limited. We introduce fluorescence emission-Brillouin scattering imaging (FBi), a method for the parallel and all-optical measurements of mechanical properties and fluorescence at the submicrometer scale in living organisms. Using FBi, we showed that changes in cellular hydrostatic pressure and cytoplasm viscoelasticity modulate the mechanical signatures of plant ECMs. We further established that the measured "stiffness" of plant ECMs is symmetrically patterned in hypocotyl cells undergoing directional growth. Finally, application of this method to Arabidopsis thaliana with photoreceptor mutants revealed that red and far-red light signals are essential modulators of ECM viscoelasticity. By mapping the viscoelastic signatures of a complex ECM, we provide proof of principle for the organism-wide applicability of FBi for measuring the mechanical outputs of intracellular signaling pathways. As such, our work has implications for investigations of mechanosignaling pathways and developmental biology.
authors.affiliation: Advanced Microscopy Facility, Vienna Biocenter Core Facilities, A-1030 Vienna, Austria. kareem.elsayad@vbcf.ac.at youssef.belkhadir@gmi.oeaw.ac.at.
authors.forename: Kareem
authors.initials: K
authors.lastname: Elsayad
authors.affiliation: Gregor Mendel Institute, Austrian Academy of Sciences, Vienna Biocenter, A-1030 Vienna, Austria.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Werner
authors.affiliation: Gregor Mendel Institute, Austrian Academy of Sciences, Vienna Biocenter, A-1030 Vienna, Austria.
authors.forename: Marçal
authors.initials: M
authors.lastname: Gallemí
authors.affiliation: Gregor Mendel Institute, Austrian Academy of Sciences, Vienna Biocenter, A-1030 Vienna, Austria.
authors.forename: Jixiang
authors.initials: J
authors.lastname: Kong
authors.affiliation: Advanced Microscopy Facility, Vienna Biocenter Core Facilities, A-1030 Vienna, Austria.
authors.forename: Edmundo R
authors.initials: ER
authors.lastname: Sánchez Guajardo
authors.affiliation: Advanced Microscopy Facility, Vienna Biocenter Core Facilities, A-1030 Vienna, Austria.
authors.forename: Lijuan
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Laboratoire Reproduction et Développement des Plantes, Univ Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, F-69342 Lyon, France.
authors.forename: Yvon
authors.initials: Y
authors.lastname: Jaillais
authors.affiliation: Gregor Mendel Institute, Austrian Academy of Sciences, Vienna Biocenter, A-1030 Vienna, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Greb
authors.affiliation: Gregor Mendel Institute, Austrian Academy of Sciences, Vienna Biocenter, A-1030 Vienna, Austria. kareem.elsayad@vbcf.ac.at youssef.belkhadir@gmi.oeaw.ac.at.
authors.forename: Youssef
authors.initials: Y
authors.lastname: Belkhadir
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009154:Mutation