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Fig. 1. Effects of NotchICD on neural and paraxial mesodermal markers at the neural plate stage. Embryos were injected with 1 ng of notchICD mRNA in one cell at the 2- or 4-cell stage and fixed at neural plate stage (B,C,E–K), when sibling control embryos reached stages 13–14 (A,D). They were revealed by ISH with the following probes: myoD (purple staining in A–E,H,I), myf5 (purple staining in F–G) and sox2 (turquoise staining in F–G; purple staining in J,K). Brown dots correspond to immunolocalization of the Myc-tag epitope fused to NotchICD. All photographs were oriented with the injected side towards the right. (D) Transverse section of the sibling control embryo shown in (A). Two layers are apparent in the paraxial mesoderm: one dorsal, expressing higher levels of myoD transcripts (dl, green arrow) and the other ventral, expressing lower levels of myoD transcripts (vl, yellow arrow). The dotted red line depicts the boundary between both layers and arrowheads point to their lateral limits (green: dl; yellow: vl). (E) Transverse section of an embryo injected with notchICD mRNA. The dorsal layer of paraxial mesoderm appears to be missing from the injected side (right), while the ventral layer remains. (F′) Transverse section of the embryo shown in F. (G) Transverse section of an embryo similar to the one shown in (F). The same references as in (D) are used for the dorsal and ventral layers of the paraxial mesoderm as revealed by myf5 expression. (H) Transverse section of the embryo shown in (B). (I) Transverse section of the embryo shown in (C). White bars in (E,H,I) indicate the thickness of the neural ectoderm. no, notochord. Black arrowheads in (F′,G,K) point to the lateral limits of the sox2 domain. |
