title: Imaging Drosophila brain by combining cryo-soft X-ray microscopy of thick vitreous sections and cryo-electron microscopy of ultrathin vitreous sections.
abstract: Cryo-soft X-ray microscopy is an emerging imaging tool complementary to cryo-electron microscopy, allowing to image frozen hydrated specimens ten to hundred times thicker, but at lower resolution. We describe how the method, so far restricted to isolated small cells or cell monolayers, can be extended to large cells and tissue. We image the synapses of the Kenyon cells in frozen hydrated Drosophila brains combining cryo-soft X-ray microscopy of thick vitreous sections, and cryo-electron microscopy of ultrathin vitreous sections. We show how to obtain frozen hydrated sections of thicknesses ranging from 40 nm up to 2.5 μm, by tuning the sectioning speed of the cryo-microtome. A fluorescent stereo-microscope mounted on the cryo-microtome allowed us to target the regions of interest after GFP-labeling of synapses. Thick cryo-sections were imaged by cryo-soft X-ray microscopy at a resolution better than 25 nm, while ultrathin cryo-sections of the same regions were explored in parallel at the nanometre level of resolution by cryo-electron microscopy.
authors.affiliation: Laboratoire de Physique des Solides, UMR8502 CNRS-Université Paris 11, Bâtiment 510, 91405 Orsay Cedex, France. Electronic address: amelie.leforestier@u-psud.fr.
authors.forename: Amélie
authors.initials: A
authors.lastname: Leforestier
authors.affiliation: PHENIX Laboratory, UMR 8234, CNRS-Université Pierre et Marie Curie, 75252 Paris, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Levitz
authors.affiliation: Genes and Dynamics of Memory Systems, Brain Plasticity Unit, CNRS, ESPCI-ParisTech, PSL Research University, Paris, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Preat
authors.affiliation: Helmholtz-Zentrum Berlin, Institute for Soft Matter and Functional Materials, Albert Einstein Str 15, D-12489 Berlin, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Guttmann
authors.affiliation: PHENIX Laboratory, UMR 8234, CNRS-Université Pierre et Marie Curie, 75252 Paris, France.
authors.forename: Laurent J
authors.initials: LJ
authors.lastname: Michot
authors.affiliation: Genes and Dynamics of Memory Systems, Brain Plasticity Unit, CNRS, ESPCI-ParisTech, PSL Research University, Paris, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Tchénio
mesh_terms: D000818:Animals; D001921:Brain / Q000648:ultrastructure*; D020285:Cryoelectron Microscopy / Q000379:methods*; D004330:Drosophila / Q000648:ultrastructure*; D005615:Freezing; D005629:Frozen Sections / Q000379:methods; D014965:X-Rays
keywords: Cryo-electron microscopy; Cryo-soft X-ray microscopy; Multiscale imaging; Mushroom body; Vitreous sections; Water widow