title: Conical Fourier shell correlation applied to electron tomograms.
abstract: The resolution of electron tomograms is anisotropic due to geometrical constraints during data collection, such as the limited tilt range and single axis tilt series acquisition. Acquisition of dual axis tilt series can decrease these effects. However, in cryo-electron tomography, to limit the electron radiation damage that occurs during imaging, the total dose should not increase and must be fractionated over the two tilt series. Here we set out to determine whether it is beneficial fractionate electron dose for recording dual axis cryo electron tilt series or whether it is better to perform single axis acquisition. To assess the quality of tomographic reconstructions in different directions here we introduce conical Fourier shell correlation (cFSCe/o). Employing cFSCe/o, we compared the resolution isotropy of single-axis and dual-axis (cryo-)electron tomograms using even/odd split data sets. We show that the resolution of dual-axis simulated and cryo-electron tomograms in the plane orthogonal to the electron beam becomes more isotropic compared to single-axis tomograms and high resolution peaks along the tilt axis disappear. cFSCe/o also allowed us to compare different methods for the alignment of dual-axis tomograms. We show that different tomographic reconstruction programs produce different anisotropic resolution in dual axis tomograms. We anticipate that cFSCe/o can also be useful for comparisons of acquisition and reconstruction parameters, and different hardware implementations.
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands; Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands. Electronic address: c.a.diebolder@lumc.nl.
authors.forename: C A
authors.initials: CA
authors.lastname: Diebolder
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands. Electronic address: f.g.a.faas@lumc.nl.
authors.forename: F G A
authors.initials: FG
authors.lastname: Faas
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands. Electronic address: a.j.koster@lumc.nl.
authors.forename: A J
authors.initials: AJ
authors.lastname: Koster
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands. Electronic address: R.I.Koning@lumc.nl.
authors.forename: R I
authors.initials: RI
authors.lastname: Koning
mesh_terms: D016880:Anisotropy; D003198:Computer Simulation; D020285:Cryoelectron Microscopy / Q000379:methods*; D004307:Dose-Response Relationship, Radiation; D055032:Electron Microscope Tomography / Q000379:methods*; D005583:Fourier Analysis; D007091:Image Processing, Computer-Assisted / Q000379:methods*
keywords: Conical Fourier shell correlation; Cryo-electron microscopy; Dual-axis cryo-electron tomography; Fourier shell correlation; Resolution estimation