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QBE Seminar: “Cryo-Electron Microscopy: From Cells to Molecules”
March 13 @ 1:00 pm - 2:00 pm
ABSTRACT: Electron microscopy has long been the method of choice for anything that requires better than approx. 10 nm resolution. Historically, specimens of cells and tissues were typically prepared by plastic-embedding and sectioning, while molecular structures were viewed with either negative staining or sometimes surface metal-shadowing. All these methods limited the achievable resolution to 2-3 nm at best. Mid 1980’s cryo-electron microscopy was developed for biological specimens. By embedding specimens in vitreous ice, the image contrast was now formed by the actual protein densities, rather than stains and metal coats, allowing a direct view of biological structures, including on cellular specimens. However, near-atomic detail could only be reached with 2-D crystalline arrays, or in very few cases with helical assemblies. This all changed roughly ten years ago when new detector technology added an additional boost to cryo-EM. These so-called direct electron detectors opened the path to near-atomic resolution, not only for crystals but for all molecular structures that allow image averaging. Today, cryo-EM plays a complementary role in biological structure determination with X-ray-crystallography and NMR-spectroscopy.
BIO: Andreas Hoegner is a full time Professor at the Department of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, CO. In the past he has served as the Director of the Boulder NIH-NCRR, (from June 2012: NIH-NIGMS) facility for the 3-D Structure of Cells from February 2006 to 2013.He currently researches the functional and structural analyses by 3-D cryo-electron microscopy of cytoskeletal assemblies and large macromolecular structures as well as cellular organelles.