This award partially supports the acquisition of a high-pressure freezing and freeze substitution instruments for the electron microscopy (EM) Core facility at the University of Chicago. This technology will allow biologists to perform advanced EM by taking advantage of recent developments in immunocytochemistry and electron tomography. Compared to standard aldehyde fixation, cryofixation has the advantage of immobilizing cellular structures within milliseconds, thereby avoiding common fixation artifacts such as shape changes and membrane fusion. Cryofixation is useful for immunocytochemistry because structure can be well preserved without loss of antigenicity. Performing cryofixation at high pressures allows relatively thick samples to be frozen without being damaged by ice crystal formaton. This method is particularly appropriate for electron tomography, which enables biological structures to be reconstructed in three dimensions at nanometer resolution. In recent years, electron tomography has become a powerful tool for studying cellular processes such as organelle remodeling, membrane trafficking, and mitotic spindle dynamics. Several researchers at the University of Chicago have collaborated with groups at other institutions to perform high-pressure freezing and/or electron tomography of yeast, protist, and mammalian cells, and other cell biology and physiology researchers here need these techniques to answer pressing scientific questions. Users of the new techniques will include postdocs, graduate students, and undergraduates in University labs, as well as undergraduates who visit the University for summer research internships. High-pressure freezing has not been available in Chicago or the immediate vicinity, so the requested system will also be a valuable addition for researchers at nearby institutions. In addition, the new equipment and methods will be incorporated into classroom teaching at the graduate and undergraduate levels.
