The focused issue on Image-processing methods for electron microscopy of biological specimens is introduced. The virtual issue is available at https://journals.iucr.org/special_issues/2025/imageprocessing.

Bovine, porcine and human insulin data sets are isomorphous in terms of unit cell and symmetry. Through enhancements to the multi-crystal clustering methods in DIALS, species-pure data sets are automatically separated by new uncertainty-weighted calculations of pairwise correlation coefficients, algorithm improvements and integration of the OPTICS spatial density clustering method.

Model-independent visualization of oxygen-evolving center-omit electron-density maps of dark-adapted photosystem II reveals the inner workings of this four-step/four-chamber combustion engine running in a reverse direction.

The myricetin-bound crystal structure of the SARS-CoV-2 helicase reveals a conserved allosteric binding site. Guided by these structural insights, caffeic acid derivatives identified through virtual screening were experimentally validated as novel natural inhibitors of NSP13.