Fig. 5. Targeted misexpression of Abd-A in neuroblast clones mimics the PcG mutant phenotype. (A) Schematic of the larval CNS showing the expression domain of Abd-A (see also Fig. 4B,E). (B-F') Confocal images of late third-instar ventral ganglia immunostained for Abd-A (magenta) and the clonal markers CD8::GFP (B, green) or nuclear ß-galactosidase (C-F, green). Shown are ventral views at the junction between the endogenous domain of abdA expression and the more anterior thoracic region carrying clones. Anterior is at the top. Coexpression of Abd-A and the clonal marker is visible in white (e.g. see Fig. 4B). Close-up views in D-F are shown as split channels for clarity. Targeted misexpression of Abd-A under tubulinGAL4 control in wild-type MARCM clones generates small neuroblast lineages (UAS-abd-A). (B) A large-field view of the ventral ganglia (outlined with dashed lines) shows small clusters of nuclei expressing Abd-A, anterior to the endogenous expression domain in the abdomen. (C) In a similar field, most of the small Sce mutant clones also show ectopic expression of Abd-A. (D-F) Close-up views of the thoracic area immediately anterior to the endogenous Abd-A domain and carrying a clone of the genotype indicated. (D'-F') Abd-A expression in the same field without the clonal marker. A wild-type clone in the thorax contains a large progeny around the neuroblast and does not express Abd-A (D,D', neuroblast outlined with dots). Targeted misexpression of Abd-A results in small clones lacking a neuroblast (E,E'). Coexpression of P35 with Abd-A restores to a wild-type-like clone (F,F'), in spite of the elevated level of Abd-A in the neuroblast (dotted circle). Scale bars: B,C, 25 µm; D-F, 10 µm.