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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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Related in: MedlinePlus

Effect of canthus removal on amnioserosa cell recoil and ventralward tension is a decreasing function of the initial distance away from incision site. (A–D) Plots of the amnioserosa cell parameters in the amnioserosa cell sheet before and after canthus removal as a function of distance from the site of incision in four single canthus–removal embryos and four native embryos (A′–D′) over the same time interval. The “before” state was ∼30 s before cutting, and the “after” state was ∼2–3 min after the initial cut. The “site of incision” reference point for native embryos is the relative position where a cut would occur. The plot of each embryo is labeled 1–4 with an assigned color. (A) Plot of the amnioserosa cell centroid displacement parallel to the dorsal midline (i.e., along anterior-posterior axis) both before and after canthus removal with respect to the initial distance from the cut site. (A′) Same measurement as A in a native embryo over the same time interval. (B) Plot of the amnioserosa cell centroid displacement (in micrometers) perpendicular to the midline (i.e., along dorsal-ventral axis) before and after canthus removal with respect to the initial distance from the cut site. (B′) Same measurement as B in a native embryo over the same time interval. (C) Plot of change in the length-to-width ratio of the amnioserosa cells before and after canthus removal with respect to the initial distance from the cut site. (C′) Same measurement as C in a native embryo over the same time interval. (D) Plot of percentage change in the amnioserosa cell area before and after canthus removal with respect to the initial distance from the cut site. (D′) Same measurement as D in a native embryo over the same time interval.
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Figure 6: Effect of canthus removal on amnioserosa cell recoil and ventralward tension is a decreasing function of the initial distance away from incision site. (A–D) Plots of the amnioserosa cell parameters in the amnioserosa cell sheet before and after canthus removal as a function of distance from the site of incision in four single canthus–removal embryos and four native embryos (A′–D′) over the same time interval. The “before” state was ∼30 s before cutting, and the “after” state was ∼2–3 min after the initial cut. The “site of incision” reference point for native embryos is the relative position where a cut would occur. The plot of each embryo is labeled 1–4 with an assigned color. (A) Plot of the amnioserosa cell centroid displacement parallel to the dorsal midline (i.e., along anterior-posterior axis) both before and after canthus removal with respect to the initial distance from the cut site. (A′) Same measurement as A in a native embryo over the same time interval. (B) Plot of the amnioserosa cell centroid displacement (in micrometers) perpendicular to the midline (i.e., along dorsal-ventral axis) before and after canthus removal with respect to the initial distance from the cut site. (B′) Same measurement as B in a native embryo over the same time interval. (C) Plot of change in the length-to-width ratio of the amnioserosa cells before and after canthus removal with respect to the initial distance from the cut site. (C′) Same measurement as C in a native embryo over the same time interval. (D) Plot of percentage change in the amnioserosa cell area before and after canthus removal with respect to the initial distance from the cut site. (D′) Same measurement as D in a native embryo over the same time interval.

Mentions: The most dramatic effect of the single-canthus cut was the displacement of centroids along the anterior–posterior axis away from the site of the cut (Figures 5, A and A′, and 6, A and A′). The centroids of cells closest to the dissected canthus were displaced the most. Moreover, the displacement of the centroids furthest from the cut (and nearest the intact canthus) appeared indistinguishable from that of unperturbed, native embryos. Indeed, we observed an inverse relationship between the displacement along the dorsal midline and the distance from the site of the cut that was well approximated by an exponential decay (Figure 6A; n = 8, R2 > 0.89). This exponential decay was consistently observed for all embryos we examined, regardless of the stage of closure.


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)

Effect of canthus removal on amnioserosa cell recoil and ventralward tension is a decreasing function of the initial distance away from incision site. (A–D) Plots of the amnioserosa cell parameters in the amnioserosa cell sheet before and after canthus removal as a function of distance from the site of incision in four single canthus–removal embryos and four native embryos (A′–D′) over the same time interval. The “before” state was ∼30 s before cutting, and the “after” state was ∼2–3 min after the initial cut. The “site of incision” reference point for native embryos is the relative position where a cut would occur. The plot of each embryo is labeled 1–4 with an assigned color. (A) Plot of the amnioserosa cell centroid displacement parallel to the dorsal midline (i.e., along anterior-posterior axis) both before and after canthus removal with respect to the initial distance from the cut site. (A′) Same measurement as A in a native embryo over the same time interval. (B) Plot of the amnioserosa cell centroid displacement (in micrometers) perpendicular to the midline (i.e., along dorsal-ventral axis) before and after canthus removal with respect to the initial distance from the cut site. (B′) Same measurement as B in a native embryo over the same time interval. (C) Plot of change in the length-to-width ratio of the amnioserosa cells before and after canthus removal with respect to the initial distance from the cut site. (C′) Same measurement as C in a native embryo over the same time interval. (D) Plot of percentage change in the amnioserosa cell area before and after canthus removal with respect to the initial distance from the cut site. (D′) Same measurement as D in a native embryo over the same time interval.
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Related In: Results  -  Collection

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Figure 6: Effect of canthus removal on amnioserosa cell recoil and ventralward tension is a decreasing function of the initial distance away from incision site. (A–D) Plots of the amnioserosa cell parameters in the amnioserosa cell sheet before and after canthus removal as a function of distance from the site of incision in four single canthus–removal embryos and four native embryos (A′–D′) over the same time interval. The “before” state was ∼30 s before cutting, and the “after” state was ∼2–3 min after the initial cut. The “site of incision” reference point for native embryos is the relative position where a cut would occur. The plot of each embryo is labeled 1–4 with an assigned color. (A) Plot of the amnioserosa cell centroid displacement parallel to the dorsal midline (i.e., along anterior-posterior axis) both before and after canthus removal with respect to the initial distance from the cut site. (A′) Same measurement as A in a native embryo over the same time interval. (B) Plot of the amnioserosa cell centroid displacement (in micrometers) perpendicular to the midline (i.e., along dorsal-ventral axis) before and after canthus removal with respect to the initial distance from the cut site. (B′) Same measurement as B in a native embryo over the same time interval. (C) Plot of change in the length-to-width ratio of the amnioserosa cells before and after canthus removal with respect to the initial distance from the cut site. (C′) Same measurement as C in a native embryo over the same time interval. (D) Plot of percentage change in the amnioserosa cell area before and after canthus removal with respect to the initial distance from the cut site. (D′) Same measurement as D in a native embryo over the same time interval.
Mentions: The most dramatic effect of the single-canthus cut was the displacement of centroids along the anterior–posterior axis away from the site of the cut (Figures 5, A and A′, and 6, A and A′). The centroids of cells closest to the dissected canthus were displaced the most. Moreover, the displacement of the centroids furthest from the cut (and nearest the intact canthus) appeared indistinguishable from that of unperturbed, native embryos. Indeed, we observed an inverse relationship between the displacement along the dorsal midline and the distance from the site of the cut that was well approximated by an exponential decay (Figure 6A; n = 8, R2 > 0.89). This exponential decay was consistently observed for all embryos we examined, regardless of the stage of closure.

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