title: High resolution atomic force microscopy of double-stranded RNA.
abstract: Double-stranded (ds) RNA mediates the suppression of specific gene expression, it is the genetic material of a number of viruses, and a key activator of the innate immune response against viral infections. The ever increasing list of roles played by dsRNA in the cell and its potential biotechnological applications over the last decade has raised an interest for the characterization of its mechanical properties and structure, and that includes approaches using Atomic Force Microscopy (AFM) and other single-molecule techniques. Recent reports have resolved the structure of dsDNA with AFM at unprecedented resolution. However, an equivalent study with dsRNA is still lacking. Here, we have visualized the double helix of dsRNA under near-physiological conditions and at sufficient resolution to resolve the A-form sub-helical pitch periodicity. We have employed different high-sensitive force-detection methods and obtained images with similar spatial resolution. Therefore, we show here that the limiting factors for high-resolution AFM imaging of soft materials in liquid medium are, rather than the imaging mode, the force between the tip and the sample and the sharpness of the tip apex.
authors.affiliation: Department of Condensed Matter Physics, Universidad Autónoma de Madrid, E-28049 Madrid, Spain. julio.gomez@uam.es.
authors.forename: Pablo
authors.initials: P
authors.lastname: Ares
authors.affiliation: Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Cantoblanco, Madrid, Spain. fernando.moreno@cnb.csic.es.
authors.forename: Maria Eugenia
authors.initials: ME
authors.lastname: Fuentes-Perez
authors.affiliation: Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Cantoblanco, Madrid, Spain. fernando.moreno@cnb.csic.es.
authors.forename: Elías
authors.initials: E
authors.lastname: Herrero-Galán
authors.affiliation: Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Cantoblanco, Madrid, Spain. fernando.moreno@cnb.csic.es.
authors.forename: José M
authors.initials: JM
authors.lastname: Valpuesta
authors.affiliation: Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Cantoblanco, Madrid, Spain. fernando.moreno@cnb.csic.es.
authors.forename: Adriana
authors.initials: A
authors.lastname: Gil
authors.affiliation: Department of Condensed Matter Physics, Universidad Autónoma de Madrid, E-28049 Madrid, Spain. julio.gomez@uam.es and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049, Madrid, Spain.
authors.forename: Julio
authors.initials: J
authors.lastname: Gomez-Herrero
authors.affiliation: Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049 Cantoblanco, Madrid, Spain. fernando.moreno@cnb.csic.es.
authors.forename: Fernando
authors.initials: F
authors.lastname: Moreno-Herrero
mesh_terms: D055595:Mechanical Phenomena; D018625:Microscopy, Atomic Force; D012330:RNA, Double-Stranded / Q000737:chemistry*
chemical_list: D012330:RNA, Double-Stranded