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hand2 represses joint and dorsal pharyngeal fates. Lateral views of wholemount wild type (A,D), hand2 mutant (B,E), hand2 mutant injected with Edn1-MOs (C) and edn1 mutant (F). (A-C) bapx1 expression at 36 hpf is present at its normal location and expanded ventrally in hand2 mutants (arrow). This expansion of bapx1 in hand2 mutants is edn1-dependent, as hand2 mutants injected with Edn1-MOs lack all first arch mesenchymal expression of bapx1, whereas the first pharyngeal pouch expression domain is present (C). We found no evidence for the converse relationship, as hand2 expression appeared unaffected in bapx1-MO-injected animals (data not shown). (D-F) eng2 expression at 30 hpf, localized to constrictor dorsalis, the dorsal first arch mesodermal core (see Kimmel et al., 2001b) expands ventrally in both hand2 and edn1 mutants. e, eye; pe, pharyngeal endoderm; pp1, pharyngeal pouch 1. Scale bars: 50 μm.
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