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Complete canthi removal reveals that forces from the amnioserosa alone are sufficient to drive dorsal closure in Drosophila.

Wells AR, Zou RS, Tulu US, Sokolow AC, Crawford JM, Edwards GS, Kiehart DP - Mol. Biol. Cell (2014)

Bottom Line: Canthi maintain purse string curvature (necessary for their dorsalward forces), and zipping at the canthi shortens leading edges, ensuring a continuous epithelium at closure completion.Dissection of one or both canthi resulted in tissue recoil and flattening of each purse string.How the embryo coordinates multiple, large forces (each of which is orders of magnitude greater than the net force) during native closure and is also resilient to multiple perturbations are key extant questions.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Duke University, Durham, NC 27708.

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The leading edge response to canthus removal is most apparent near sites of incision. (A) Traces of one leading edge at different time points before, during, and after canthus removal. Traces are colored according to the time scale shown on the color bar. t = 0 marks the start of the first canthus cut. For reference, the last trace in Ai is repeated in Aii with the same number, and the last trace in Aii is repeated in Aiii. The right arrowhead in Aii (posterior end) indicates part of leading edge that exhibits subtle ventralward recoil. Both arrowheads in Aii exhibit retraction along the contour length of the leading edge. (B) Plots illustrate the similarity of responses that five individual embryos exhibit after the removal of both canthi. Each plot reports height measurements at a distinct location on five different embryos, each represented by a different color. The distinct location is illustrated in the inset of each plot, and all locations are illustrated in Figure 1Ciii. Measurements from a native embryo are shown as a gray line in each plot.
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Figure 3: The leading edge response to canthus removal is most apparent near sites of incision. (A) Traces of one leading edge at different time points before, during, and after canthus removal. Traces are colored according to the time scale shown on the color bar. t = 0 marks the start of the first canthus cut. For reference, the last trace in Ai is repeated in Aii with the same number, and the last trace in Aii is repeated in Aiii. The right arrowhead in Aii (posterior end) indicates part of leading edge that exhibits subtle ventralward recoil. Both arrowheads in Aii exhibit retraction along the contour length of the leading edge. (B) Plots illustrate the similarity of responses that five individual embryos exhibit after the removal of both canthi. Each plot reports height measurements at a distinct location on five different embryos, each represented by a different color. The distinct location is illustrated in the inset of each plot, and all locations are illustrated in Figure 1Ciii. Measurements from a native embryo are shown as a gray line in each plot.

Mentions: To evaluate more quantitatively the effects of double canthus removal experiments, we characterized the effects of double canthus removal in greater detail when laser perturbation was performed midway through closure (Figure 3). The embryos were more precisely staged to improve reproducibility (see Materials and Methods and Discussion). We evaluated six embryos that were labeled with DE-cadherin-GFP and administered the laser protocol when the distance between the symmetry points of the leading edges (i.e., at the maximum dorsal opening) was 68 ± 1 μm, which is in the middle stage of closure. In each embryo, we selected six additional locations for height measurements—three on either side of the symmetry point (diagrammed in Figures 1C and 2C)—and plotted their heights over time (Figure 3B). The reproducibility of staged embryos is highlighted in Figure 3B, where the responses of all six embryos at a given position are shown on the same plot.


Complete canthi removal reveals that forces from the amnioserosa alone are sufficient to drive dorsal closure in Drosophila.

Wells AR, Zou RS, Tulu US, Sokolow AC, Crawford JM, Edwards GS, Kiehart DP - Mol. Biol. Cell (2014)

The leading edge response to canthus removal is most apparent near sites of incision. (A) Traces of one leading edge at different time points before, during, and after canthus removal. Traces are colored according to the time scale shown on the color bar. t = 0 marks the start of the first canthus cut. For reference, the last trace in Ai is repeated in Aii with the same number, and the last trace in Aii is repeated in Aiii. The right arrowhead in Aii (posterior end) indicates part of leading edge that exhibits subtle ventralward recoil. Both arrowheads in Aii exhibit retraction along the contour length of the leading edge. (B) Plots illustrate the similarity of responses that five individual embryos exhibit after the removal of both canthi. Each plot reports height measurements at a distinct location on five different embryos, each represented by a different color. The distinct location is illustrated in the inset of each plot, and all locations are illustrated in Figure 1Ciii. Measurements from a native embryo are shown as a gray line in each plot.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Figure 3: The leading edge response to canthus removal is most apparent near sites of incision. (A) Traces of one leading edge at different time points before, during, and after canthus removal. Traces are colored according to the time scale shown on the color bar. t = 0 marks the start of the first canthus cut. For reference, the last trace in Ai is repeated in Aii with the same number, and the last trace in Aii is repeated in Aiii. The right arrowhead in Aii (posterior end) indicates part of leading edge that exhibits subtle ventralward recoil. Both arrowheads in Aii exhibit retraction along the contour length of the leading edge. (B) Plots illustrate the similarity of responses that five individual embryos exhibit after the removal of both canthi. Each plot reports height measurements at a distinct location on five different embryos, each represented by a different color. The distinct location is illustrated in the inset of each plot, and all locations are illustrated in Figure 1Ciii. Measurements from a native embryo are shown as a gray line in each plot.
Mentions: To evaluate more quantitatively the effects of double canthus removal experiments, we characterized the effects of double canthus removal in greater detail when laser perturbation was performed midway through closure (Figure 3). The embryos were more precisely staged to improve reproducibility (see Materials and Methods and Discussion). We evaluated six embryos that were labeled with DE-cadherin-GFP and administered the laser protocol when the distance between the symmetry points of the leading edges (i.e., at the maximum dorsal opening) was 68 ± 1 μm, which is in the middle stage of closure. In each embryo, we selected six additional locations for height measurements—three on either side of the symmetry point (diagrammed in Figures 1C and 2C)—and plotted their heights over time (Figure 3B). The reproducibility of staged embryos is highlighted in Figure 3B, where the responses of all six embryos at a given position are shown on the same plot.

Bottom Line: Canthi maintain purse string curvature (necessary for their dorsalward forces), and zipping at the canthi shortens leading edges, ensuring a continuous epithelium at closure completion.Dissection of one or both canthi resulted in tissue recoil and flattening of each purse string.How the embryo coordinates multiple, large forces (each of which is orders of magnitude greater than the net force) during native closure and is also resilient to multiple perturbations are key extant questions.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Duke University, Durham, NC 27708.

Show MeSH
Related in: MedlinePlus