The Department of Cell Biology has a long tradition of excellence and innovation in the field of imaging, and electron microscopy in particular. Thanks to the pioneering work of Yale professors Russell Barrnett and George Palade, electron microscopy has become an intrinsic part of many projects in Cell Biology.
The ascent of Molecular Biology has not caused de demise of electron microscopy that some had predicted, but on the contrary has resulted in a renewed interest for morphological approaches as the many gene products identified through genetic screens have to be characterized in terms of function and subcellular localization. As a result, there has been a gradual shift away from purely descriptive electron microscopy towards immunocytochemical approaches where proteins are visualized in the electron microscope after binding of antibodies and heavy metal conjugates.
One of the major technological approaches that we focus on in the Electron Microscopy Laboratory is that of immuno-gold labeling on ultrathin cryosections. This technique presents the advantage that labeling can be quantified and therefore the relative concentration of a protein in various subcellular compartments can be estimated. This approach has been used successfully, for example, to study the architecture of the mammalian Golgi apparatus and its division through mitosis, and the role of the trans Golgi network and endosomes in protein sorting and the biogenesis of polarized epithelial cells. Often if not always these projects are conducted in parallel with light microscopical approaches where proteins are tagged with the green fluorescent protein and followed in the fluorescent light microscope in live cells. We are presently trying to reinforce this synergy between light and electron microscopy, by making results obtained by immuno-electron microscopy more directly comparable to those obtained by fluorescent light microscopy. One approach we are focusing on is to develop the ability to carry out immuno-gold labeling on single cells that have previously observed under the light microscope, so that structures observed at the light microscope can then be further characterized at higher resolution in the electron microscope. Another approach that we wish to develop is that of 3-D reconstruction of cells by electron microscopy after immuno-gold labeling, in order to gain spatial information of the immuno-labeling that until now was only available by light microscopy.
Also visit the CCMI-EM webpage: http://cellserv.med.yale.edu/imaging/ccmi/electron.html
Center for Cell and Molecular Imaging (CCMI)
Ira Mellman
Graham Warren
Cellular Imaging (Derek)
CINEMA lab
