Fig. 4

ASC mutant neuroblasts are temporarily stalled and devoid of stem cell identity markers. A Stage 9 wt neuroblasts (left panels) express Dpn and have divided to generate Pros positive GMCs. In Df(1)scB57 embryos (right panels) neuroblasts do not express Dpn and have not yet divided to produce GMCs. The weak Dpn signal in the mutant embryo comes from the NE layer above the delaminated NBs. B In stage 11, mutant neuroblasts have rebounded in Dpn expression and cell divisions to produce GMCs. The sparse Dpn and Pros positive cells outside the broad band of the VNC are PNS precursors, which are also strongly reduced in the ASC mutant. C Nvy-GFP is absent in mutant neuroblasts during stage 9. Remaining expression comes from more laterally positioned PNS precursors, D Nvy expression does not rebound in mutant neuroblasts at st 11. E Scrt is lost or very weak in mutant neuroblasts at st 9. F Scrt expression rebounds in stage 11 Df(1)scB57 neuroblasts and GMCs. G Stage 9 B57 mutant neuroblasts, not expressing Dpn, express hunckback (Hb). Notice the lack of Hb positivity on the engrailed (En) stripe and the lateral NB column in the mutant. H In stage 10 B57 mutants, Hb is seen over the En stripe. A summary of genomic characteristics of selected proneural TF targets tested is provided in Additional file 2: Table S6