Fig. 4. Characterization of brain lobe size and proliferation rate of neuroblasts in Drosophila babo mutant larvae. (A) Brain lobe size as a function of larval stage. Larvae were dissected in PBS, mounted without coverslips, and brain lobe diameter was measured using a calibrated reticule. P-value is from Student's t-test. Error bars are standard deviation. (B,C) White prepupa (wpp) brain lobes of either wild type (B) or babo^32/52 mutant (C) were labeled by anti-Dachshund (red), anti-Miranda (green) and anti-Scribbled (blue) antibodies. (B) One half wild-type wpp optic lobe; anterior is up, posterior is down, lateral is right and medial is left. Scrib outlines all cell cortices in the wpp optic lobe; Mir marks medial neuroblasts of the optic lobe; Dach marks LPCs (arrow) and central plug progenitor cells from the IPC (arrowhead). (C) Three-quarters of a much smaller babo^32/52 wpp optic lobe. Much of the optic lobe remains primitive neuroepithelial cells indicative of a younger optic lobe [Scrib⁺, Mira^- and Deadpan (Dpn), data not shown]. Dach marks the first progenitors to be born from the IPC (arrowhead). (D) Quantification of the average number of medial optic lobe (OL) neuroblasts (Nbs) per optic section of wandering third-instar larva brain (11 sections on left and right lobes for a total of 22 sections). On average, about 8-10 Miranda-positive optic lobe neuroblasts are seen per inner optic section of wild-type control brain lobes, whereas babo mutants have only about 4 Miranda-positive optic lobe neuroblasts per section. (E-G) MARCM clonal analysis of wild-type clones (arrows in E) or a babo mutant clone (arrow in F) 48 hours after heat shock. Brain lobes were stained by anti-Elav antibody (red). Mutant or wild-type clones are marked by GFP expression. The number of cells in well-defined clones within the optic lobes were counted and the quantification is shown (G). (H-J) MARCM clonal analysis of the proliferation rates of wild-type central larval brain neuroblasts (arrows in H) or a babo⁹ mutant central brain neuroblast clone (arrow in I) 48 hours after heat shock. Larval brain lobes were stained with anti-Prospero antibody (red) and anti-Elav antibody (blue). (J) Quantification of cell numbers derived from individual central brain neuroblasts.