title: Automated cell tracking identifies mechanically oriented cell divisions duringDrosophilaaxis elongation.
abstract: Embryos extend their anterior-posterior (AP) axis in a conserved process known as axis elongation.Drosophilaaxis 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.
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada M5S 3G9.|Ted Rogers Centre for Heart Research, University of Toronto, Toronto, Ontario, Canada M5G 1M1.
authors.forename: Michael F Z
authors.initials: MF
authors.lastname: Wang
authors.affiliation: Ted Rogers Centre for Heart Research, University of Toronto, Toronto, Ontario, Canada M5G 1M1.|Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada M5S 3G5.
authors.forename: Miranda V
authors.initials: MV
authors.lastname: Hunter
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada M5S 3G9.
authors.forename: Gang
authors.initials: G
authors.lastname: Wang
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada M5S 3G9.|Ted Rogers Centre for Heart Research, University of Toronto, Toronto, Ontario, Canada M5G 1M1.
authors.forename: Christopher
authors.initials: C
authors.lastname: McFaul
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada M5S 3G9.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Yip
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada M5S 3G9 rodrigo.fernandez.gonzalez@utoronto.ca.|Ted Rogers Centre for Heart Research, University of Toronto, Toronto, Ontario, Canada M5G 1M1.|Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada M5S 3G5.|Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8.
authors.forename: Rodrigo
authors.identifier: 0000-0003-0770-744X
authors.initials: R
authors.lastname: Fernandez-Gonzalez
mesh_terms: D000818:Animals; D001331:Automation; D001696:Biomechanical Phenomena; D019521:Body Patterning; D002452:Cell Count; D002455:Cell Division; D048430:Cell Shape; D058948:Cell Tracking / Q000379:methods*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000196:embryology*; D004475:Ectoderm / Q000166:cytology; D008648:Mesoderm / Q000166:cytology
keywords: Image analysis; Laser ablation; Machine learning; Morphogenesis; Oriented cell division; Time-lapse microscopy