2/ (2) Saturday 3:00 PM at #EDRC2023: @LOBrienLab grad student Miriam Sun talks in the Stem Cells & Regeneration session on work w @ensanders12! What happens when you eat a toxin? Real-time movies of gut damage in vivo show how stem cells 'kick it up a Notch' for rapid repair.

1/ #EDRC2023 - Don't miss out on a double feature from @LOBrienLab! Friday, 3:30 PM: Lucy kicks off the world-famous EDRC Gut Workshop! Discover how the gut exerts control over its size by loosening its grip on cell extrusions. @EDRC2023

Seeing is believing at #ISSCR2023! Come & be amazed at the Live Imaging and Super-Res Microscopy session Tues 1:30PM Rm 259! @JoergBewersdorf & Lucy @LOBrienLab chair a wowser line up of single-molecule, STORM, FIB-SEM, intravital, holotomography, & more! 🍿 not provided 😉

15/ FIB-SEM of early-stage junction formation, morphometric analyses, and more in the full paper! rdcu.be/c8Msm Many 👏 to Tony Galenza, @paolamr90, Irina Kolotuev, and all the other authors on this 💪 team effort!

14/ In awesome, convergent work, @chenjiajiachen @DStjohnston also identified PACs as intercellular lumens. They did it by analyzing asymmetric membrane label at clone boundaries! 🧠 Check out their powerful genetic analysis here 👉 bit.ly/3Gec1gf)

13/ Full 3D reconstruction showed that these structures are intercellular lumens; the concave apical surface is a deep plasma membrane invagination. Here, this new cell (red) has two PACs (cyan, magenta), which are surrounded by a huge, blanket-like occluding junction (green).

12/ FIB-SEM lets us see the ultrastructure of entire tissue volumes. This feature turned out to be crucial: Although the apical structures looked like vacuoles in many single EM slices (left), there was always a small region that was contiguous with the plasma membrane (right)!

10/ To nail this down, postdoc Tony Galenza cleverly synchronized a cohort of stem cell progeny and followed them over time. The synced cohort moves through stages 1-5 in sequence, arguing that our order is correct! 🎉

8/ Later, basal-to-apical remodeling of the junction opens the PAC to the gut lumen. We think this cautious, multi-step approach is a hedge against the high cost of premature integration.

7/ The PAC grows directly beneath a broad occluding junction that forms between the new cell and its mature neighbors. The junction (not shown in this image) shelters the PAC (arrowhead) from the gut's lumenal contents (here, fluorescent dextran in yellow).