Dear all, Having systematically contributed to the development of Cryo-EM and structural biology since its very beginning, I now am saddened that original contributions are overlooked as the field rapidly advances. Let me just recall the factual early history of these resolution criteria:
The Fourier Ring Correlation (FRC) was first introduced - and the name first used in the literature - as a resolution metric for two-dimensional images by [van Heel et al. 1982] in “Arthropod hemocyanin structures studied by image analysis.” In the same year [Saxton & Baumeister (1982)] published a resolution measure, the “spatial frequency correlation function”, whose paper contained no formulas and was tailored specifically to assess 2D crystal reconstructions. The three-dimensional extension of the FRC, namely, the Fourier Shell Correlation (FSC), was already announced in [van Heel et al. 1982], but was later established formally in [Harauz & van Heel (1986)]. (Computers in those days did not have enough address space to hold 3D reconstruction “in core”. Therefore the 2D-to-3D extension was not straightforward). In a recent review [Bhakta & van Heel, 2024], we discussed how FRC and FSC are mostly misattributed to [Saxton & Baumeister (1982)], a trend entrenched by early studies that somehow perpetuated that idea. Although [van Heel et al. 1982] was published in a difficult-to-access conference journal, it can now simply be downloaded (from ResearchGate), thereby ensuring that such scientific originality is not misinterpreted as plagiarism, as we have experienced recently. References van Heel, M., Keegstra, W., Schutter, W., & van Bruggen, E. F. J. (1982). Arthropod hemocyanin structures studied by image analysis. Life Chemistry Reports, 1, 167–216. Saxton, W. O., & Baumeister, W. (1982). The correlation averaging of a regularly arranged bacterial cell envelope protein. Journal of Microscopy, 127(2), 127–138. Harauz, G., & van Heel, M. (1986). Exact filters for general geometry three-dimensional reconstruction. Optik, 73, 146–156. Bhakta, S., & van Heel, M. (2024). Single-Particle Cryo-EM: What happens inside the Black Box? OSF Preprints. Note that I stopped correcting scientifically refuted statements appearing systematically in Wikipedia’s (“Fourier Shell Correlation”). Please check its “history”. By the way, the FRC and FSC have themselves now been corrected because the Signal-to-Noise-Ratio is an incorrect information metric [van Heel & Schatz, arXiv, 2020]. Cheers, Marin van Heel Campinas, Aug 19th 2026 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
