Slices through a cryo-electron tomography volumes. A: Magnetospirillum magneticum sp AMB-1: adapted from [] with permission. General features of AMB-1 cells are highlighted in this 12-nm thick slice from a cryo-ET reconstruction: outer membrane (OM), inner membrane (IM), peptidoglycan layer (PG), ribosomes (R), outer membrane bleb (B), chemoreceptor bundle (CR), poly-b-hydroxybutyrate granule (PHB), gold fiduciary marker (G), intracellular fiber (F) and the magnetosome chain (MG). (B: Tomographically reconstructed microtubule-Eg5 kinesin complexes compared to a helical reconstruction (inset: Eg5 motor domain shown as yellow densities). Red and orange frames mark the location of the tomographic slice with respect to the total microtubule volume. Red cuts at the lumen of the tube, and orange cuts along the outer surface). Both tomograms demonstrate molecular preservations to ~3nm resolution. AMB-1 images reveal that magnetosomes are invaginations of the inner cell membrane. Image B: Julia Cope, Hoenger lab, CU-Boulder). Scale bars = 100 nm.

Cryo-ET reconstruction of cadherin molecules bridging the extracellular space in a desmosome. This tomogram was obtained from a cryo-section cut from a fully vitrified specimen. A: Due to the absence of chemical fixation and/or any substitution processes cryo-ET reveals molecular details at high resolution. The inset outlines the density of a spanning molecular bridge. B: Image as in A with the membranes marked in pink and the connecting cadherins-based density in purple. C: 3-D volume obtained from an average of subtomograms. D: Molecular model with the X-ray structures of C-cadherin fitted into the volume shown in C. Figure adapted from [] (with permission).

Tomographic 3-D reconstructions from ~300-nm thick plastic sections, showing both the fine details and the global view of cellular structure that are visible in this kind of ET. A: 20 nm slice from a tomogram of the plant cell cytokinetic organelle; the “phragmoplast”, and its associated cell plate assembly matrix (cpam) are outlined in red. For details see []. Figure adapted with permission. B – D: ~2 nm slices from a tomogram of a mitotic spindle showing that RF/FSF preserves molecular details, such as defects in microtubule structure caused by katanin []. Arrows indicate breaks in the microtubule wall that are absent when katanin is deleted. E: 3-D model of phragmoplast microtubules, linking their plus-ends to the cpam. These models demonstrate the complexity of 3-D data that can be analyzed by tomography and tomographic modeling methods [] (with permission).

3D localization of antigens by the combination of ET with immuno-labeling. Arabidopsis meristems were prepared by RF/FSF, sliced ~300 nm, labeled with antibodies to α-1,2 mannosidase 1, and imaged as tilt series for ET []. C1 – 6 label successive cisternae in the cis, medial, and trans parts of this Golgi complex, and the position of the antigen is marked by 15 nm gold particles through indirect immuno-localization. (With permission).