Fig. 6.

Missexpression of active Notch induces differentiation of dI1 interneurons at the expense of RP traits, yet has no effect on early NC development. a–d Electroporation of control GFP. e–h Electroporation of aN2-GFP. Note that control GFP has no effect on BAMBI mRNA expression (a, b) whereas its upregulation is compromised upon aN2 transfection (e, f). No BarHL1-positive dI1 interneurons are apparent in the RP of control embryos (c, d) (N = 4). In contrast, numerous BarHlL-positive interneurons are present in the RP of aN2-treated cases (g, h, arrowheads). (N = 6). i Quantification of the number of BarHL1+ interneurons/section present in the RP (N = 6 for both control and aN2, *p < 0.02). j–o Electroporation of control GFP (j–l) or aN2 (m–o) followed by immunolabeling with BarHL1 antibody. Note that control GFP had no effect on interneuron development (N = 4) whereas no BarHL1+ interneurons were apparent in aN2-treated tubes (N = 6, arrowhead). p–s Gain of Notch activity has no effect on NC migration. Electroporation of control GFP or aN2 at 22ss followed 1 day later by immunostaining for GFP (green) and the NC marker HNK-1 (red). Note in both cases the migration of GFP+/HNK1+ NC cells. t Quantification of the number of GFP-labeled migrating NC cells per section from hemi-neural tubes of control (N = 6) and aN2-treated (N = 7) embryos (p = 0.6, ns). Bar = 50 μm