Freeze! Show Your Hands… Apprehending Motion and Handedness to Get the Most from Cryo-Electron Tomography

Data processing for cryo-electron tomography (cryo-ET), while rooted in the principles of single particle analysis (SPA), presents unique challenges, pitfalls, but also advantages. The tilt series used for tomogram reconstruction comprises low-dose, low signal-to-noise ratio (SNR) images, often impacted by significant drift caused by stage tilting. At the same time, feature-rich cryo-ET samples, such as FIB-milled lamellae, offer abundant signal for robust motion correction and CTF fitting. Properly harnessing this potential during subtomogram averaging can help achieving higher resolutions.

A critical yet often overlooked aspect of cryo-ET processing is ensuring the correct handedness of reconstructed volumes. Unlike SPA, cryo-ET inherently preserves absolute handedness throughout image processing. However, achieving this requires careful navigation of microscope, detector, and reconstruction conventions—challenges compounded by the lack of universal standardization. Confidence in data processing accuracy remains the foundation of reliable cryo-ET results. Moving forward, rigorous validation protocols and unified conventions will be essential for advancing cryo-ET as a mature structural biology technique, uniquely capable of resolving biomolecular structures in their native environments.