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Investigating Cell and Tissue Mechanics during Drosophila Embryogenesis using Laser Microsurgery

dc.creatorLynch, Holley Ellen
dc.description.abstractLiving tissues are active, non-linear viscoelastic materials that move drastically, often in concert, during embryogenesis. In many cases, the mechanics of this motion remain unknown. Using a combination of laser microsurgery and finite-element simulations, I explore the mechanics of Drosophila embryogenesis during two consecutive stages: germband retraction and dorsal closure. First, I investigate the interactions between two tissues, the amnioserosa and germband, as they move cohesively across the surface of the embryo during germband retraction. I find that the amnioserosa mechanically assists germband retraction but only by pulling on a few germband segments – specifically those around the curve. Retraction also depends on cell autonomous elongation in the germband, modeled by a polarization of cell edge tensions that aligns perpendicular rather than parallel to the principle stress direction. Cell elongation aligns with this polarization in most germband segments, but in a few, again mostly around the curve, cell elongation aligns with the direction of greatest anisotropic stress. Second, I probe the tension distribution within a single contracting tissue, the amnioserosa during dorsal closure. These tests demonstrate that the amnioserosa acts more like a continuous sheet than a cellular foam, where tensile stress is carried both by cell-cell interfaces and by an apical actin network. Together these results further our understanding of the physics of embryogenesis and provide a framework for future experiments probing how the mechanics change in mutants that fail to complete germband retraction or dorsal closure.
dc.subjectfinite-element model
dc.subjecttissue mechanics
dc.subjectlaser microsurgery
dc.subjectdorsal closure
dc.subjectgermband retraction
dc.titleInvestigating Cell and Tissue Mechanics during Drosophila Embryogenesis using Laser Microsurgery
dc.contributor.committeeMemberKalman Varga
dc.contributor.committeeMemberVolker E. Oberacker
dc.contributor.committeeMemberChris J. Janetopoulos
dc.contributor.committeeMemberJohn P. Wikswo Jr.
dc.type.materialtext University
dc.contributor.committeeChairM. Shane Hutson

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