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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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There is no observable effect on the cell area oscillation frequency after canthus removal. (A) Plots of cell areas of all tracked cells in the frequency domain for 30 min after canthus removal in each of six cut embryos (Ai–Avi). (A′) Plot of cell areas in the frequency domain of all cut embryos is superimposed in blue, and the average of the blue curve is bold in red. (B, B′) Same measurements as in A and A′ for three native embryos (Bi–Biii). (C) Plot of the normalized sum of area curves in the frequency domain between cut (red) and native (blue) embryos (red curve is bold red in A′, blue curve is bold red in B′). (D–D′′) Steps in the area curve processing for Fourier analysis for an individual cell. (D) Blue curve is the original area curve in the spatial domain. The red curve is a polynomial fit of the area curve. (D′) Residual of area and polynomial fit in D. This procedure functions as a selective high-pass filter to enhance higher-frequency oscillations that represent the active oscillation in each cell. (D′′) Fourier transform of D′. The process highlighted in D– D′′ for each cell is used to generate plots of each embryo or of multiple embryos shown in A–C. That is, each plot in A′ and B′ includes all of the tracked cells in a given embryo.
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Figure 8: There is no observable effect on the cell area oscillation frequency after canthus removal. (A) Plots of cell areas of all tracked cells in the frequency domain for 30 min after canthus removal in each of six cut embryos (Ai–Avi). (A′) Plot of cell areas in the frequency domain of all cut embryos is superimposed in blue, and the average of the blue curve is bold in red. (B, B′) Same measurements as in A and A′ for three native embryos (Bi–Biii). (C) Plot of the normalized sum of area curves in the frequency domain between cut (red) and native (blue) embryos (red curve is bold red in A′, blue curve is bold red in B′). (D–D′′) Steps in the area curve processing for Fourier analysis for an individual cell. (D) Blue curve is the original area curve in the spatial domain. The red curve is a polynomial fit of the area curve. (D′) Residual of area and polynomial fit in D. This procedure functions as a selective high-pass filter to enhance higher-frequency oscillations that represent the active oscillation in each cell. (D′′) Fourier transform of D′. The process highlighted in D– D′′ for each cell is used to generate plots of each embryo or of multiple embryos shown in A–C. That is, each plot in A′ and B′ includes all of the tracked cells in a given embryo.

Mentions: To evaluate quantitatively the area time series, we used Fourier methods to measure oscillation frequencies. The time series of apical cross-sectional area exhibit low- and high-frequency bands that correspond to ingression and reversible oscillations, respectively (Sokolow et al., 2012). The high-frequency band is due to the active forcing function along the perimeter of an amnioserosa cell. For each amnioserosa cell in each embryo, we estimated the high-frequency band and computed its discrete Fourier transform (DFT) during the first 30 min after dissection (Figure 8, D–D′′). We compared the periodicity of amnioserosa cells in regions both near and away from the removed canthus, as well as the periodicity of cells in cut versus uncut embryos.


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)

There is no observable effect on the cell area oscillation frequency after canthus removal. (A) Plots of cell areas of all tracked cells in the frequency domain for 30 min after canthus removal in each of six cut embryos (Ai–Avi). (A′) Plot of cell areas in the frequency domain of all cut embryos is superimposed in blue, and the average of the blue curve is bold in red. (B, B′) Same measurements as in A and A′ for three native embryos (Bi–Biii). (C) Plot of the normalized sum of area curves in the frequency domain between cut (red) and native (blue) embryos (red curve is bold red in A′, blue curve is bold red in B′). (D–D′′) Steps in the area curve processing for Fourier analysis for an individual cell. (D) Blue curve is the original area curve in the spatial domain. The red curve is a polynomial fit of the area curve. (D′) Residual of area and polynomial fit in D. This procedure functions as a selective high-pass filter to enhance higher-frequency oscillations that represent the active oscillation in each cell. (D′′) Fourier transform of D′. The process highlighted in D– D′′ for each cell is used to generate plots of each embryo or of multiple embryos shown in A–C. That is, each plot in A′ and B′ includes all of the tracked cells in a given embryo.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Figure 8: There is no observable effect on the cell area oscillation frequency after canthus removal. (A) Plots of cell areas of all tracked cells in the frequency domain for 30 min after canthus removal in each of six cut embryos (Ai–Avi). (A′) Plot of cell areas in the frequency domain of all cut embryos is superimposed in blue, and the average of the blue curve is bold in red. (B, B′) Same measurements as in A and A′ for three native embryos (Bi–Biii). (C) Plot of the normalized sum of area curves in the frequency domain between cut (red) and native (blue) embryos (red curve is bold red in A′, blue curve is bold red in B′). (D–D′′) Steps in the area curve processing for Fourier analysis for an individual cell. (D) Blue curve is the original area curve in the spatial domain. The red curve is a polynomial fit of the area curve. (D′) Residual of area and polynomial fit in D. This procedure functions as a selective high-pass filter to enhance higher-frequency oscillations that represent the active oscillation in each cell. (D′′) Fourier transform of D′. The process highlighted in D– D′′ for each cell is used to generate plots of each embryo or of multiple embryos shown in A–C. That is, each plot in A′ and B′ includes all of the tracked cells in a given embryo.
Mentions: To evaluate quantitatively the area time series, we used Fourier methods to measure oscillation frequencies. The time series of apical cross-sectional area exhibit low- and high-frequency bands that correspond to ingression and reversible oscillations, respectively (Sokolow et al., 2012). The high-frequency band is due to the active forcing function along the perimeter of an amnioserosa cell. For each amnioserosa cell in each embryo, we estimated the high-frequency band and computed its discrete Fourier transform (DFT) during the first 30 min after dissection (Figure 8, D–D′′). We compared the periodicity of amnioserosa cells in regions both near and away from the removed canthus, as well as the periodicity of cells in cut versus uncut embryos.

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