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Figure 1
General Smart Leginon Autoscreen fully automated, unattended multi-grid screening workflow. CryoEM grids with samples are prepared and loaded into a cryoTEM with an automated specimen-exchange system. In Autoscreen, the microscope operator imports settings from an example session, including (1) Ng, the number of groups to separate the squares in the grid atlas by, based on square area, mean intensity or Ptolemy score; (2) Ns, the total number of squares that will be collected; and (3) Nh, the number of holes that will be collected for each square. For each grid in the microscope, Smart Leginon Autoscreen will automatically target the highest-ranked (`best') square in each group and sample Nh random, threshold-filtered holes for each square, where Ptolemy determines rankings. Exposure magnification ice thickness estimations are determined in real time by Leginon and automated pre-processing in Appion (e.g. frame alignment and CTF estimation) is initiated at the end of each grid collection. If another grid is listed for screening, then Autoscreen automatically moves to the next grid and initiates a new collection session in the database. Once all grids are screened, Autoscreen safely returns the microscope to its default state and sends a message of completion to a designated Slack channel to alert operators and users. Each step in Autoscreen may be performed unattended by command line or used as independent modules in the Leginon GUI. Atlas scale bar is 500 µm, grid tile image scale bar is 50 µm, hole image scale bar is 1 µm.

IUCrJ
Volume 10| Part 1| January 2023| Pages 77-89
ISSN: 2052-2525
https://doi.org/10.1107/S2052252522010624