Cryo-electron tomography: 3-dimensional imaging of soft matter

The advent of cryogenic-transmission electron microscopy (cryoTEM) signified a breakthrough in the in situ imaging of hydrated specimens of biological and synthetic origin allowing their study in a state of preservation that is close to native. An inherent limitation to cryoTEM, however, is that images are 2-dimensional projections of the 3-dimensional objects, resulting in the overlapping of multiple features that cannot be discerned. Cryo-electron tomography (cryoET) is essential to overcome this limitation. In this technique images of the specimen are acquired at different tilt angles and then reconstructed into the 3-dimensional object, revealing detailed information on the structure, morphology or 3-dimensional spatial organization of (bio) macromolecules and (macro) molecular assemblies. This information then can be coupled to processes happening in the 3-dimensional space, making cryoET an invaluable tool to bridge between the structural organization in space and the function or activity of macromolecular complexes at the nanometre scale.