EML Technology Development
The EML continues to establish capabilities and workflows according to needs in the NCI. Recently, cryo-electron microscopy and room temperature electron tomography have been established as core services. We continue to work on a robust cryo-electron tomography workflow and we are developing workflows for correlated fluorescence/confocal and electron microscopy.
Correlated Fluorescence and Electron Microscopy
Often it would be useful to observe the ultrastuctural environment of a fluorescence labeled protein in the cell rather than only the fluorescence signal. We are working on robust workflows to allow processing of cells for electron microscopy after fluorescence imaging and location of the same area/cell for correlated microscopy. We are also developing a way to create fusion proteins that will allow fluorescence imaging and location in electron microscopy with the same protein tag.
An important new development in electron microscopy is the application of electron tomography in biomedical research. In principle, electron tomography is similar to x-ray tomography used for radiological imaging of humans; the specimen is viewed from many different directions, and the resulting projections are computationally synthesized into a three-dimensional density map of the object of interest. Electron tomography is currently the only imaging modality capable of producing three-dimensional representations of single macromolecular specimens in the resolution range of ~5 nm. A major challenge for cryo-electron tomography is the fact that the low electron dose used for cryo-EM imaging has to be further distributed to the about 60 tilt images in the tomography dataset to prevent damage of the cryo specimen from electron radiation. The single tilt images are therefore very low signal to noise and often only the final 3 dimensional reconstruction allows useful interpretation. Click here to learn more about Cryo-EM.