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Fig. 6. Effects of blocking Notch signaling on neural and paraxial mesodermal markers at the late gastrula and neural plate stage. Embryos were injected in one cell at the 4-cell stage with 0.5 ng of delta-1STU mRNA (A,B,D,D′,E,E′), 1 ng of delta-1STU mRNA (C,F,F′) or 20 ng of Notch Mo (G–L). They were fixed when sibling controls reached stage 12.5 (G,J), 14 (A–F,K) or 15 (H,I,I′,L) and were revealed by ISH of myf5 (purple staining in A,D), myoD (purple staining in B,E,G,H,I) or sox2 (purple staining in C,F,J–L). Embryos injected with delta-1STU mRNA and the embryo shown in (K) were co-injected with BDA as tracer, which was revealed after a chromogenic reaction with Magenta Phos (A,B,D,E) or BCIP (turquoise staining, C,F,K). In the rest of the embryos, the injected side was determined by the fluorescence of the morpholino before the ISH procedure. Whole embryos are shown in dorsal views, anterior up, except in (A), which shows a dorsal-posterior view. All photographs were oriented with the injected side towards the right. The horizontal yellow dotted lines in (A,B) show the plane of transverse sections shown in the inset in (A) and in the photograph in (E), respectively. (D,D′) Transverse section at the level of the neurenteric canal of an embryo similar to the one shown in (A). (I) Transverse section at the mid-trunk level of an embryo similar to the one shown in (H). (D′,E′,F′,I′) Nuclear Hoescht staining of the sections shown in (D,E,F,I), respectively. Green arrow in (D): prospective dorsal layer (dl) of the paraxial mesoderm. Yellow arrow in (D): prospective ventral layer (vl) of the paraxial mesoderm. Green arrow in (E): dorsal layer (dl) of the paraxial mesoderm. Yellow arrow in (E): ventral layer (vl) of the paraxial mesoderm. nc: neurenteric canal; no: notochord. The vertical yellow dotted line in F depicts the embryo's midline, and yellow arrowheads point to the lateral borders of the sox2 domain, showing the reduction of the neural plate on the medio-lateral axis on the injected side. Double arrows in (L) show the difference in the width of the sox2 domain between the injected- and the non-injected side. |
