Multiple mechanisms determine ER network morphology during the cell cycle in Xenopus egg extracts

Video 4.
The leading ends of ER tubules track with the plus ends of MTs. Demembranated sperm was added to a crude interphase X. laevis egg extract containing the hydrophobic dye DiIC₁₈ (in red) and a GFP fusion of the plus end tracking protein EB-1 (EB-1–GFP; in green). The samples were imaged after 30-min incubation. Shown is the merged image of the two fluorescence channels. The yellow arrowheads point at EB-1 comets, marking the growing plus ends of MTs and the tip of extending ER tubules. The blue arrowhead indicates the fusion site of an ER tubule with another. Time-lapsed images were acquired by spinning-disk confocal microscopy at 2-s intervals for 1 min. The video is shown at four frames per second. Still images of this video were used for Fig. 3 A. Bar, 2 µm.