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. Author manuscript; available in PMC: 2016 Apr 11.
Published in final edited form as: Science. 2012 Feb 3;335(6068):590–593. doi: 10.1126/science.1212867

Figure 1. Notch inhibits a Hox11/13b-dependent regulatory circuit in mesoderm.

Figure 1

(A) Diagram of endomesoderm blastomeres: Large (red) micromere progeny are adjacent to veg2 cells in which early cWnt activates endoderm and mesoderm specification (hatched light green) in early blastulae. By HB stage, veg2 descendants form outer (presumptive endoderm, yellow) and inner (presumptive mesoderm, green) rings. Large micromere progeny (red) ingress by MB stage. (B to Q) Endodermal brachyury (bra), foxa and blimp1b transcripts are downregulated in Hox11/13b morphants (MASO). (B, F, N) hox11/13b mRNA is upregulated in Hox11/13b morphants, because Hox11/13b represses its own transcription (11). (K to M) Ectopic expression of brachyury (bra), foxa and blimp1b mRNA occurs in inner veg2 cells of Notch morphants. hox11/13b mRNA concentration is low through auto-repression by ectopic Hox11/13b protein (11) (J). (O to Q) In Notch+Hox11/13b double morphants, ectopic expression of Hox11/13b target genes in inner veg2 cells (arrows) is significantly lower (Q). Scale bar=20 µm.