XB-IMG-159109
Xenbase Image ID: 159109
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Figure 8. Trailing edge retraction by rear-end membrane remodeling and macropinocytosis.(A) Regions of interest. Schematic illustrates endoderm cells in a vegetal explant, viewed through a glass slide with non-adhesive BSA coating. Direction of migration is to the left. Region 1 (ROI1) shows the plane of focus at the level of the surface of the outermost cells, and region 2 (ROI2) a plane through the cell bodies. ROI1 and ROI2 are approximately 0.5 µm apart. (B) Trailing edge representation at different planes of focus. The cell rear of a membrane labelled endoderm cell within the vegetal explant is shown. Images represent ROI1 and ROI2 introduced in (A). Membrane protrusions (arrows) are clearly visible at the substrate level. (C) Tail retraction of cell co-expressing mRFP and Lifeact-GFP. (D) Cluster of vesicles (yellow arrow) is visible at the trailing edge (top row). Enlargement of inset (box) region for all panels of the sequence (bottom row). (E) Uptake of extracellular fluid at the trailing edge (top row). Membrane label (mRFP) and probe (dextran) are shown separately in black and white (middle panels). Vesicle of interest (yellow arrow) is indicated. A nearby yolk platelet (Y) is noted. Sequence of process is illustrated below. (F) Ultrastructure of endoderm cell tail in the embryo. Overview (left), higher magnification (i) of the trailing edge shows vesicle clusters (yellow arrows). (G) Ultrastructure of vesicles near the rear membrane (left). Putative stages of vesicle internalization (right, top row) and corresponding illustrated interpretations (red arrows; bottom row) are shown. (H) Quantification of vesicle sizes from the trailing edge at different gastrula stages. Box plots show the median, interquartile range, maximum and minimum. Data were cumulatively sampled from 12 embryos collected from different egg batches. (I) Rab5c-CFP is enriched at the trailing edge during migration (left panels). Magnification of the cell-rear (inset i–iii) shows that Rab5 is localized to sites of prominent membrane remodeling (yellow arrows).10.7554/eLife.27190.027Figure 8—source data 1. Quantification of vesicle diameter.Figure 8—figure supplement 1. Scanning electron micrograph of cell trailing edge in vivo (left).Magnification (right) shows heterogeneous vesicles (yellow arrow) inside a partially removed membrane, and pits (white arrow) in the intact membrane. Image published in: Wen JW and Winklbauer R (2017) © 2017, Wen et al. This image is reproduced with permission of the journal and the copyright holder. This is an open-access article distributed under the terms of the Creative Commons Attribution license Larger Image Printer Friendly View |