Journal of Electron Microscopy Advance Access published online on July 30, 2009
Journal of Electron Microscopy, doi:10.1093/jmicro/dfp036
Evaluation of imaging plates as recording medium for images of negatively stained single particles and electron diffraction patterns of two-dimensional crystals
1 Department of Cell Biology
2 Howard Hughes Medical Institute, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115
3 Department of Biochemistry & Biophysics, W. M. Keck Advanced Microscopy Laboratory, University of California, 600 16th Street, San Francisco, CA 94143, USA
* To whom correspondence should be addressed. E-mail: twalz{at}hms.harvard.edu
We evaluated imaging plates (IPs) and the DITABIS Micron scanner for their use in recording images of negatively stained single-particle specimens and electron diffraction patterns of two-dimensional crystals. We first established the optimal imaging and read-out conditions for images of negatively stained single-particle specimens using the signal-to-noise ratio of the images as the evaluation criterion. We found that images were best recorded on IPs at a magnification of 67 000x, read out with a gain setting of 20 000 and a laser power setting of 30% with subsequent binning over 2 x 2 pixels. Our results show that for images of negatively stained specimens, for which the resolution is limited to
20 Å, IPs are a good alternative to EM film. We also compared IPs with a 2K x 2K Gatan charge-coupled device (CCD) camera for their use in recording electron diffraction patterns of sugar-embedded two-dimensional crystals. Diffraction patterns of aquaporin-0 recorded on IPs and with the CCD camera showed reflections beyond 3 Å and had similar RFriedel as well as Rmerge values. IPs can thus be used to collect diffraction patterns, but CCD cameras are more convenient and remain the best option for recording electron diffraction patterns.
Keywords imaging plates, negative staining, single-particle electron microscopy, two-dimensional crystals, electron diffraction
Received 28 April 2009, accepted 23 June 2009