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Fig. S2
Combined mutation of notch2 and notch3 causes dorsal skeletal defects.
(A-D) Expression of Notch receptors in the pharyngeal arches. At 36 hpf, notch1a (A, magenta) and notch1b (B, magenta) are expressed in the ectodermal cleft adjacent to the first pharyngeal pouch but are undetectable in dlx2a+ NCCs (green). By contrast, notch2 (C) is strongly expressed in intermediate/dorsal NCCs (white arrow), and notch3 is expressed in dorsal second arch NCCs (white arrow), arch core mesoderm (dlx2a-negative, orange arrow), and the first ectodermal cleft (white arrowhead). (E-I) Mutation of notch2 (F) or notch3 (G) alone does not affect skeletal patterning, though a subset of notch2-/-; notch3+/- mutants (H) show some jag1b-like dorsal skeletal defects. Combined loss of both genes (I) results in a severe phenotype (two examples shown in I, I') consisting of a significant reduction in the size of the Hm and a shift towards a more posterior position (black open arrowhead), variable fusions of the second arch joint (black arrow), and abnormalities in the posterior Pq (black arrowhead). The overall size reduction and failure of bone mineralization are likely non-specific consequences of cardiac edema. Scale bar in D = 20 μm; scale bar in I = 100 μm.