Fig. 3

Gα₁₃ and RhoGEF act downstream of S1pr2. (A-F) Disruption of either Gα₁₃ or RhoGEF suppresses the gastrulation defects resulting from overexpression of S1pr2. (A-C) ntl expression detected by in situ hybridization in control embryos and in embryos injected with s1pr2 RNA, alone or together with gna13ab MOs, at 8 hpf. Dorsal view, with vegetal pole (VP, blue line) towards the bottom; black arrows indicate positions of the deep-cell margin (dcm); double-headed blue arrows indicate distance from the dcm to VP; red lines indicate axial mesoderm. (D,E) Bright-field images of 35 hpf embryos injected with the s1pr2 RNA, alone or together with the Arhgef11RGS RNA. Lateral view; red asterisk indicates cyclopia; arrow indicates pericardial edema; arrowheads indicate tail blisters. (F) Frequencies of embryos exhibiting gastrulation defects. **P<0.01 versus s1pr2 RNA-injected embryos. Data are mean±s.e.m. (G-I) Interference with RhoGEF function disrupts myocardial migration. Embryo injected with the Arhgef11RGS RNA at 35 hpf. (G) Lateral bright-field image showing pericardial edema (arrow) and tail blisters (arrowheads). The inset shows a high-magnification image of the tail region in the boxed area. (H) Overlay of epifluorescence and bright-field images, showing the locations of EGFP-expressing cardiomyocytes (arrows) in Tg(myl7:EGFP) embryos. Ventral view. (I) myl7 expression, as detected by in situ hybridization in control embryos and in embryos injected with s1pr2 RNA, alone or together with gna13ab MOs, at 8 hpf. Dorsoanterior view. Scale bars: 100 μm.