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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

Removal of a single canthus causes amnioserosa cell recoil and ventralward tension. (A–D) Heat maps showing changes to different cell parameters in the amnioserosa cell sheet of an embryo before and after canthus removal and (A′–D ′) in a native embryo over the same time interval. The “before” state was ∼30 s before cutting, and the “after” state was ∼1–2 min after the initial cut. (A) A heat map of amnioserosa cell centroid displacement (in micrometers) parallel to the dorsal midline (i.e., along anterior-posterior axis), both before and after canthus removal. (A′) Same measurement as A in a native embryo over the same time interval. (B) A heat map of amnioserosa cell centroid displacement (in micrometers) perpendicular to the dorsal midline (i.e., along dorsal-ventral axis), both before and after canthus removal. (B′) Same measurement as B in a native embryo over the same time interval. (C) A heat map of the change in amnioserosa cell length-to-width ratio before and after canthus removal. (C′) Same measurement as C in a native embryo over the same time interval. The length-to-width ratio is defined as the size of the cell in the dorsal-ventral axis over the size in the anterior-posterior axis. (D) Heat map of the percentage change in amnioserosa cell area before and after canthus removal. (D′) Same measurement as D in a native embryo over the same time interval. (E) Images of the embryo in A–D before canthus removal and (E′) after canthus removal. The red line denotes the site of laser incision. (F, F′) Images of the native embryo in A′–D′ over the same time interval as in E and E′.
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Figure 5: Removal of a single canthus causes amnioserosa cell recoil and ventralward tension. (A–D) Heat maps showing changes to different cell parameters in the amnioserosa cell sheet of an embryo before and after canthus removal and (A′–D ′) in a native embryo over the same time interval. The “before” state was ∼30 s before cutting, and the “after” state was ∼1–2 min after the initial cut. (A) A heat map of amnioserosa cell centroid displacement (in micrometers) parallel to the dorsal midline (i.e., along anterior-posterior axis), both before and after canthus removal. (A′) Same measurement as A in a native embryo over the same time interval. (B) A heat map of amnioserosa cell centroid displacement (in micrometers) perpendicular to the dorsal midline (i.e., along dorsal-ventral axis), both before and after canthus removal. (B′) Same measurement as B in a native embryo over the same time interval. (C) A heat map of the change in amnioserosa cell length-to-width ratio before and after canthus removal. (C′) Same measurement as C in a native embryo over the same time interval. The length-to-width ratio is defined as the size of the cell in the dorsal-ventral axis over the size in the anterior-posterior axis. (D) Heat map of the percentage change in amnioserosa cell area before and after canthus removal. (D′) Same measurement as D in a native embryo over the same time interval. (E) Images of the embryo in A–D before canthus removal and (E′) after canthus removal. The red line denotes the site of laser incision. (F, F′) Images of the native embryo in A′–D′ over the same time interval as in E and E′.

Mentions: As described earlier, we used laser surgery to dissect a single canthus from the dorsal opening (n = 8; Figure 5, E and E′) and then investigated the consequences for the behavior of amnioserosa cells. We compared the amnioserosa cells in the last image taken before the cut (∼30 s before) and the first image taken after the cut (∼1–2 min after; Figure 5, E and E′). For native, uncut embryos, we chose images that differ over the same time interval as that of cut embryos (Figure 5, F and F′).


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)

Removal of a single canthus causes amnioserosa cell recoil and ventralward tension. (A–D) Heat maps showing changes to different cell parameters in the amnioserosa cell sheet of an embryo before and after canthus removal and (A′–D ′) in a native embryo over the same time interval. The “before” state was ∼30 s before cutting, and the “after” state was ∼1–2 min after the initial cut. (A) A heat map of amnioserosa cell centroid displacement (in micrometers) parallel to the dorsal midline (i.e., along anterior-posterior axis), both before and after canthus removal. (A′) Same measurement as A in a native embryo over the same time interval. (B) A heat map of amnioserosa cell centroid displacement (in micrometers) perpendicular to the dorsal midline (i.e., along dorsal-ventral axis), both before and after canthus removal. (B′) Same measurement as B in a native embryo over the same time interval. (C) A heat map of the change in amnioserosa cell length-to-width ratio before and after canthus removal. (C′) Same measurement as C in a native embryo over the same time interval. The length-to-width ratio is defined as the size of the cell in the dorsal-ventral axis over the size in the anterior-posterior axis. (D) Heat map of the percentage change in amnioserosa cell area before and after canthus removal. (D′) Same measurement as D in a native embryo over the same time interval. (E) Images of the embryo in A–D before canthus removal and (E′) after canthus removal. The red line denotes the site of laser incision. (F, F′) Images of the native embryo in A′–D′ over the same time interval as in E and E′.
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Related In: Results  -  Collection

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Figure 5: Removal of a single canthus causes amnioserosa cell recoil and ventralward tension. (A–D) Heat maps showing changes to different cell parameters in the amnioserosa cell sheet of an embryo before and after canthus removal and (A′–D ′) in a native embryo over the same time interval. The “before” state was ∼30 s before cutting, and the “after” state was ∼1–2 min after the initial cut. (A) A heat map of amnioserosa cell centroid displacement (in micrometers) parallel to the dorsal midline (i.e., along anterior-posterior axis), both before and after canthus removal. (A′) Same measurement as A in a native embryo over the same time interval. (B) A heat map of amnioserosa cell centroid displacement (in micrometers) perpendicular to the dorsal midline (i.e., along dorsal-ventral axis), both before and after canthus removal. (B′) Same measurement as B in a native embryo over the same time interval. (C) A heat map of the change in amnioserosa cell length-to-width ratio before and after canthus removal. (C′) Same measurement as C in a native embryo over the same time interval. The length-to-width ratio is defined as the size of the cell in the dorsal-ventral axis over the size in the anterior-posterior axis. (D) Heat map of the percentage change in amnioserosa cell area before and after canthus removal. (D′) Same measurement as D in a native embryo over the same time interval. (E) Images of the embryo in A–D before canthus removal and (E′) after canthus removal. The red line denotes the site of laser incision. (F, F′) Images of the native embryo in A′–D′ over the same time interval as in E and E′.
Mentions: As described earlier, we used laser surgery to dissect a single canthus from the dorsal opening (n = 8; Figure 5, E and E′) and then investigated the consequences for the behavior of amnioserosa cells. We compared the amnioserosa cells in the last image taken before the cut (∼30 s before) and the first image taken after the cut (∼1–2 min after; Figure 5, E and E′). For native, uncut embryos, we chose images that differ over the same time interval as that of cut embryos (Figure 5, F and F′).

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