title: Scanning x-ray nanodiffraction on Dictyostelium discoideum.
abstract: We have performed scanning x-ray nanobeam diffraction experiments on single cells of the amoeba Dictyostelium discoideum. Cells have been investigated in 1), freeze-dried, 2), frozen-hydrated (vitrified), and 3), initially alive states. The spatially resolved small-angle x-ray scattering signal shows characteristic streaklike patterns in reciprocal space, which we attribute to fiber bundles of the actomyosin network. From the intensity distributions, an anisotropy parameter can be derived that indicates pronounced local variations within the cell. In addition to nanobeam small-angle x-ray scattering, we have evaluated the x-ray differential phase contrast in view of the projected electron density. Different experimental aspects of the x-ray experiment, sample preparation, and data analysis are discussed. Finally, the x-ray results are correlated with optical microscopy (differential phase contrast and confocal microscopy of mutant strains with fluorescently labeled actin and myosin II), which have been carried out in live and fixed states, including optical microscopy under cryogenic conditions.
authors.affiliation: Institut für Röntgenphysik, Georg-August-Universität Göttingen, Göttingen, Germany.
authors.forename: Marius
authors.initials: M
authors.lastname: Priebe
authors.affiliation: Institut für Röntgenphysik, Georg-August-Universität Göttingen, Göttingen, Germany.
authors.forename: Marten
authors.initials: M
authors.lastname: Bernhardt
authors.affiliation: Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Blum
authors.affiliation: Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Tarantola
authors.affiliation: Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.
authors.forename: Eberhard
authors.initials: E
authors.lastname: Bodenschatz
authors.affiliation: Institut für Röntgenphysik, Georg-August-Universität Göttingen, Göttingen, Germany. Electronic address: tsaldit@gwdg.de.
authors.forename: Tim
authors.initials: T
authors.lastname: Salditt
mesh_terms: D016880:Anisotropy; D002470:Cell Survival; D004023:Dictyostelium / Q000166:cytology*; D053758:Nanoparticles / Q000737:chemistry*; D053838:Scattering, Small Angle; D012984:Software; D014961:X-Ray Diffraction