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Mitoses generating neurons in the sub-ventricular zone require ErbB signaling. A. A timeline of experiments of AG1478 treatment. Embryos were soaked into 30 µM AG1478 solution or the control 2% DMSO from 26 to 45 hpf. Then, they were washed and grown in a fresh medium from 45 hpf. Embryos at 44, 48 and 54 hpf were collected for analyses. See also S3 Movie on the recovery of neurogenesis after removal of AG1478. B. pH3-positive mitotic cells in the OT. Removal of AG1478 at 45 hpf enhanced mitoses in the SVZ at 48 hpf prior to recovery of GFP-expressing neurons in the OT of Tg(pou4f1-hsp70l:GFP) at 54 hpf. Yellow arrows, pH3-positive cells in the SVZ. Scale bar, 10 µm. C. Quantification of the number of pH3-positive cells in the VZ (blue) and the SVZ (red) of AG1478-treated embryos and the control (white) embryos (mean ± s.e.m.; *P < 0.05, ***P < 0.001; n = 3, 5, 5 for AG1478, n = 6, 4, 6 for DMSO at 44, 48, 54 hpf, respectively). D. Quantification of GFP intensity in the OT (mean ± s.e.m.; *P < 0.05, ****P < 0.0001; n = 6, 4, 5 for AG1478, n = 6, 4, 6 for DMSO at 44, 48, 54 hpf, respectively). E. Time-lapse imaging of NPCs stochastically labeled by co-injection of UAS:mCherry/UAS:memb:GFP plasmids into Tg(pou4f1-hsp70l:GFP;SAGFF(LF)81C) embryos. After the removal of AG1478, two NPCs (1, 2; arrowheads) divided once in the SVZ (asterisk) to generate two daughter cells (a, b), and then, these cells were incorporated into the presumptive neuronal layer (NL, green bar, above the thin dotted line). Note that mitoses of these NPCs were not preceded by mitoses in the apical VZ and those NPCs began to express cytoplasmic GFP (right). An apical mitosis of another NPC or RGC labeled with membGFP was also observed in this imaging (arrow). Scale bar, 10 µm. See also S5 Movies.
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