Journal: bioRxiv

Article Title: Apical Constriction Reversal upon Mitotic Entry Underlies Different Morphogenetic Outcomes of Cell Division

doi: 10.1101/862821

Figure Lengend Snippet: (A) Non-mitotic, contractile cells between mitotic domains invaginate during gastrulation. Images are maximum intensity projections from a live fog overexpressing embryo expressing Myo::GFP and Gap43::mCherry. The ectopic furrow is shown by a white dashed line. The invagination posterior to mitotic domain (MD) 5 is the cephalic furrow (CF). (B) Cross-section views of local tissue invaginations from the embryo in (A). Images from control embryo not ectopically expressing fog are in . (C) Quantification of apical cell area and cell apex anisotropies in non-mitotic (salmon in cartoon) and mitotic (mint green in cartoon) cells. Final cell area was evaluated just before mitotic cells formed cytokinetic furrows. The time elapsed between initial and final cell area was between 5 and 20 minutes. Across 6 representative fog overexpressing embryos, 26 furrow cells and 33 mitotic domain cells were analyzed. Across 5 representative control embryos (Rhodopsin 3 shRNA line), 133 non-mitotic cells and 66 mitotic domain cells were analyzed (***, P < .0001; **, P < .01, unpaired t test). For changes in cell area, significance from 0 was determined with a one sample t test. Bottom and top edges of the boxplot are 25 th and 75 th percentiles, with median marked by the white line. Whiskers extend to the most extreme data points. (D) Cell aspect ratio increases more in embryos with ectopic fog expression. Quantification of mean change in cell aspect ratio with standard deviations between a representative control (Rhodopsin 3 shRNA line) and ectopic fog expression embryo. Cell aspect ratio is calculated as the distance from the centroid of a fitted ellipse to the ellipse edge along the major axis (a) over the distance along the minor axis (b). For ectopic fog expression embryos, 6 cells were quantified, and 7 cells were quantified for control embryos. Aspect ratio was measured up to the start of cytokinesis. (E) Apical constriction of non-mitotic cells initiate when neighboring mitotic domain cells enter mitosis. Quantification of apical cell area in a representative fog overexpressing embryo. Individual cell traces as well as averages with standard deviation are shown for mitotic domain cells (mint; n = 6 cells) and non-mitotic domain cells (salmon; n = 28 cells). The initiation of mitotic rounding is marked by the arrow. Scale bars, 15 μm.

Article Snippet: Image segmentation for quantifications of cell area and anisotropy as well as myosin intensities was performed using custom MATLAB software titled EDGE (Embryo Development Geometry Explorer; https://github.com/mgelbart/embryo-development-geometry-explorer ; Gelbart et al., 2012).

Techniques: Expressing, shRNA, Standard Deviation