HMR-1/E-cadherin expression and circumferential intercalations.

<p>(A) Low magnification of an immunostained embryo showing HMR-1::GFP (green) and the apical junction protein AJM-1 (red). Note the high level of HMR-1 in the region of the developing valve compared to the level in most other embryonic cells. The right panel is a high magnification of the valve region showing HMR-1 enrichment at the boundary between v1 and v3D, and around the v2R cell body. (B) Time-lapse images of a live embryo showing HMR-1::GFP on the left side of the cyst as pm8 moves ventrally; the pm8 nucleus is indicated by an asterisk. Note that HMR-1 associated with the ventral lamellipodium from pm8 (arrow) appears to split as the pm8 nucleus moves toward and into the lamellipodium. (C) Lower, sagittal focal plane of the same embryo as in panel B at 430 minutes. The pm8 nucleus has moved further ventral, and is now adjacent to mc3V (the mc3V nucleus is labeled 3). The line of HMR-1 between pm8 and mc3V is in the same position as the laminin tract shown in <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003772#pgen-1003772-g007" target="_blank">Figure 7F</a>. (D) Right sagittal focal plane at 430 minutes of the same embryo shown in panels B and C; the HMR-1::GFP signal has been removed to show cell shapes. v2R has intercalated dorsally, with its bulk cell body past the dorsal-ventral boundary (open arrowhead) between the int1 intestinal cells. (E) Time-lapse of a <i>hmr-1(zu389)</i> mutant embryo. The v2R nucleus and most of the cell body remain below the dorsal-ventral int1 boundary through 496 minutes, although the v2R lamellipodium (closed arrowhead) has extended dorsally. (F,G) Apical junctions (red, AJM-1) in a wild-type embryo (F) and a <i>hmr-1(zu389)</i> mutant embryo (G), taken at about 440 minutes. For cell identification, the panels to the right in each figure show an image of cell bodies and/or nuclei (green) taken 1.5 microns to the left of the midline and superimposed on the apical junction image. At the stage shown, pm8 and v1 have wrapped around the midline, but not undergone autofusion into donuts; see <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003772#pgen.1003772-Rasmussen2" target="_blank">[22]</a> for detailed description of junctions at this stage. The apical junctions in the <i>hmr-1</i> mutants are abnormal, with a large gap in the region of the pm8, v1, and the v2 cells. Similar to the <i>hmr-1</i> embryo in panel E, the v2R cell has failed to move dorsally, although its lamellipodium (arrowhead) has intercalated between v1 and v3D. Bars: (A) 10 microns; (B–G) 2.5 microns.