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Development. 2017 Apr 1;144(7):1350-1361. doi: 10.1242/dev.141473. Epub 2017 Feb 17.

Automated cell tracking identifies mechanically oriented cell divisions during Drosophila axis elongation.

Author information

1
Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada M5S 3G9.
2
Ted Rogers Centre for Heart Research, University of Toronto, Toronto, Ontario, Canada M5G 1M1.
3
Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada M5S 3G5.
4
Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada M5S 3G9 rodrigo.fernandez.gonzalez@utoronto.ca.
5
Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8.

Abstract

Embryos extend their anterior-posterior (AP) axis in a conserved process known as axis elongation. Drosophila axis elongation occurs in an epithelial monolayer, the germband, and is driven by cell intercalation, cell shape changes, and oriented cell divisions at the posterior germband. Anterior germband cells also divide during axis elongation. We developed image analysis and pattern-recognition methods to track dividing cells from confocal microscopy movies in a generally applicable approach. Mesectoderm cells, forming the ventral midline, divided parallel to the AP axis, while lateral cells displayed a uniform distribution of division orientations. Mesectoderm cells did not intercalate and sustained increased AP strain before cell division. After division, mesectoderm cell density increased along the AP axis, thus relieving strain. We used laser ablation to isolate mesectoderm cells from the influence of other tissues. Uncoupling the mesectoderm from intercalating cells did not affect cell division orientation. Conversely, separating the mesectoderm from the anterior and posterior poles of the embryo resulted in uniformly oriented divisions. Our data suggest that mesectoderm cells align their division angle to reduce strain caused by mechanical forces along the AP axis of the embryo.

KEYWORDS:

Image analysis; Laser ablation; Machine learning; Morphogenesis; Oriented cell division; Time-lapse microscopy

PMID:
28213553
DOI:
10.1242/dev.141473
[Indexed for MEDLINE]
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