title: X-rays Reveal the Internal Structure of Keratin Bundles in Whole Cells.
abstract: In recent years, X-ray imaging of biological cells has emerged as a complementary alternative to fluorescence and electron microscopy. Different techniques were established and successfully applied to macromolecular assemblies and structures in cells. However, while the resolution is reaching the nanometer scale, the dose is increasing. It is essential to develop strategies to overcome or reduce radiation damage. Here we approach this intrinsic problem by combing two different X-ray techniques, namely ptychography and nanodiffraction, in one experiment and on the same sample. We acquire low dose ptychography overview images of whole cells at a resolution of 65 nm. We subsequently record high-resolution nanodiffraction data from regions of interest. By comparing images from the two modalities, we can exclude strong effects of radiation damage on the specimen. From the diffraction data we retrieve quantitative structural information from intracellular bundles of keratin intermediate filaments such as a filament radius of 5 nm, hexagonal geometric arrangement with an interfilament distance of 14 nm and bundle diameters on the order of 70 nm. Thus, we present an appealing combined approach to answer a broad range of questions in soft-matter physics, biophysics and biology.
authors.affiliation: Institute for X-ray Physics, University of Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
authors.forename: Clément Y J
authors.initials: CY
authors.lastname: Hémonnot
authors.affiliation: Deutsches Elektronen-Synchrotron , Notkestrasse 85, 22607 Hamburg, Germany.
authors.forename: Juliane
authors.initials: J
authors.lastname: Reinhardt
authors.affiliation: Institute for X-ray Physics, University of Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
authors.forename: Oliva
authors.initials: O
authors.lastname: Saldanha
authors.affiliation: Institute of Structural Physics, Technische Universität Dresden , Zellescher Weg 16, 01069 Dresden, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Patommel
authors.affiliation: Institute for X-ray Physics, University of Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
authors.forename: Rita
authors.initials: R
authors.lastname: Graceffa
authors.affiliation: European Synchrotron Radiation Facility , 71, Avenue des Martyrs, 38043 Grenoble, France.
authors.forename: Britta
authors.initials: B
authors.lastname: Weinhausen
authors.affiliation: European Synchrotron Radiation Facility , 71, Avenue des Martyrs, 38043 Grenoble, France.|Department of Analytical Chemistry, Ghent University , Krijgslaan 281, 9000 Ghent, Belgium.
authors.forename: Manfred
authors.initials: M
authors.lastname: Burghammer
authors.affiliation: Deutsches Elektronen-Synchrotron , Notkestrasse 85, 22607 Hamburg, Germany.|Institute for Nanostructure and Solid State Physics, Department of Physics, University of Hamburg , Luruper Chaussee 149, 22761 Hamburg, Germany.
authors.forename: Christian G
authors.initials: CG
authors.lastname: Schroer
authors.affiliation: Institute for X-ray Physics, University of Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
authors.forename: Sarah
authors.initials: S
authors.lastname: Köster
mesh_terms: D002460:Cell Line; D006801:Humans; D007382:Intermediate Filaments / Q000648:ultrastructure; D007633:Keratins / Q000032:analysis / Q000648:ultrastructure*; D049329:Nanostructures / Q000737:chemistry; D014961:X-Ray Diffraction / Q000379:methods; D014965:X-Rays
chemical_list: D007633:Keratins
keywords: X-ray nanodiffraction; cytoskeleton; intermediate filaments; keratin; ptychography