SEGGA: a toolset for rapid automated analysis of epithelial cell polarity and dynamics

Farrell, Dene L.; Weitz, Ori; Magnasco, Marcelo O.; Zallen, Jennifer A.

doi:10.1242/dev.146837

Cited by 66 publications

(105 citation statements)

References 77 publications

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“…Prior to the onset of tissue elongation, individual cells take on roughly isotropic shapes and become more elongated over time ( Fig. 2A,B), consistent with previous observations (26)(27)(28)48). Ten minutes prior to tissue elongation, the average cell shape index ̅ is just above 3.81.…”

Section: Resultssupporting

confidence: 90%

“…begins to increase just prior to elongation, peaking at = 1 min ( Fig. 4B), which is consistent with observations using other cell pattern metrics (21,26,28). This peak in corresponds to stretching of the cells along the dorsalventral axis, perpendicular to the axis of germband extension, and coincides with the time period during which the presumptive mesoderm tissue is invaginating (47).…”

Section: Cell Shape and Cell Shape Alignment Together Indicate A Solisupporting

confidence: 88%

“…1B,C). The dominant contribution is from cell rearrangement (19,20,28,41), which requires a planar polarized pattern of myosin localization across the tissue (18,19) that is thought to be the driving force for rearrangement (19,21,22,40). Cell stretching along the AP axis also contributes to tissue elongation and coincides with movements of neighboring tissues (26-28, 42, 43), indicating that external forces play an important role in tissue behavior.…”

Section: Resultsmentioning

confidence: 99%

“…5C), cell rearrangement (Fig. 5D), and endoderm invagination, but still undergo mesoderm invagination (18,20,25,26,28,41).…”

Section: Cell Shape and Cell Shape Alignment Together Indicate A Solimentioning

confidence: 99%

“…Planar polarized myosin is required for cell rearrangements that converge and extend the tissue to rapidly elongate the body and is thought to produce anisotropic tensions in the tissue (19)(20)(21)(22)(23)(24)(25). In addition, the Drosophila germband experiences external forces from neighboring tissues, including the mesoderm and endoderm, which have been linked to cell shape changes in the germband during convergent extension (26)(27)(28) (Fig. 1A).…”

Section: Introductionmentioning

confidence: 99%

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Anisotropy links cell shapes to a solid-to-fluid transition during convergent extension

Wang

Merkel

Sutter

et al. 2019

Preprint

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Within developing embryos, tissues flow and reorganize dramatically on timescales as short as minutes. This includes epithelial tissues, which often narrow and elongate in convergent extension movements due to anisotropies in external forces or in internal cell-generated forces. However, the mechanisms that allow or prevent tissue reorganization, especially in the presence of strongly anisotropic forces, remain unclear. We study this question in the converging and extending Drosophila germband epithelium, which displays planar polarized myosin II and experiences anisotropic forces from neighboring tissues, and we show that in contrast to isotropic tissues, cell shape alone is not sufficient to predict the onset of rapid cell rearrangement. From theoretical considerations and vertex model simulations, we predict that in anisotropic tissues two experimentally accessible metrics of cell patterns-the cell shape index and a cell alignment index-are required to determine whether an anisotropic tissue is in a solid-like or fluid-like state. We show that changes in cell shape and alignment over time in the Drosophila germband indicate a solid-to-fluid transition that corresponds to the onset of cell rearrangement and convergent extension in wild-type embryos and are also consistent with more solid-like behavior in bnt mutant embryos. Thus, the onset of cell rearrangement in the germband can be predicted by a combination of cell shape and alignment. These findings suggest that convergent extension is associated with a transition to more fluid-like tissue behavior, which may help accommodate tissue shape changes during rapid developmental events.

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Section: Resultssupporting

confidence: 90%