Fig. 4

olig3 is controlled by Notch and regulates ngn1 and deltaA expression in the lateral neural plate. (a–d) Notch signaling controls olig3 expression. (a) olig3 expression at the two-somite stage showing the medial (m) and lateral (l) domains. (b) mib embryo at the two-somite stage showing increased and broadened expression of olig3. (c and d) Tail bud-stage embryo injected with Notch-ICD (NIC) showing dramatic reduction of olig3 expression (d) (shown phenotype > 90%, n = 20). (e–g) olig3MO rescues pigmentation in mib mutants. (e) Trunk pigmentation at 30 hpf. (f) mib embryo lacks melanocytes. (g) Rescue of the pigmentation in a mib mutant injected with olig3MO (morphant phenotype 9/10). (h–j, h′, and j′) olig3MO rescues the neural crest in DAPT-treated embryos. (h) crestin expression in a normal embryo at 30 hpf. (h′) Transverse section of the embryo in h. (i) A DAPT-treated embryo lacks most of the neural crest cells. (j) Injection of olig3MO in an embryo treated with DAPT rescues neural crest cells (morphant phenotype 9/10). (j′) Transverse section of the embryo in j. (k and l) olig3 controls the expression of deltaA in interneurons. (k) deltaA expression pattern in a four-somite-stage control embryo injected with olig3^mismMO. (l) The stripe of deltaA-positive cells corresponding to interneurons (in) is missing in embryos injected with olig3MO (morphant phenotype > 90%, n = 40). (m–o) In situ hybridizations at two-somite stage showing that olig3 activates ngn1 expression in the lateral neural plate. (m) Expression of ngn1 in motoneurons (mn), interneurons (in), and RB cells (RB) in control embryos injected with olig3^mismMO. (n) In an olig3MO-injected embryo, ngn1 is expressed only in the medialmost (mn) and lateralmost (RB) neuronal populations (morphant phenotype > 90%, n = 20). (o) Injection of olig3 mRNA up-regulates ngn1 expression (shown phenotype > 90%, n = 20). (p–s) RB and dorsal root ganglion (drg) cells are present in ngn1:GFP-transgenic embryos (13) injected with olig3MO (r and s), as in controls (p and q). Interneurons (in) are reduced or absent (q and s). Embryos are shown in dorsal view with anterior to the top (a–d and k–o), lateral view with anterior to the left (e–j), and dorsal view with anterior to the left (p–s).