Figure 1.

A screen for asymmetric division mutants in third instar larval neuroblasts. (A) Crossing scheme used to establish mutant lines and generate MARCM clones of mutations lethal before the third instar stage. The asterisk indicates an EMS-induced mutation. (B-E) Expression of asymmetric cell division markers in third instar larval neuroblasts. DNA staining (blue); Miranda (red, B, C, E); Prospero (Red, D); CD8::GFP (green, B); Inscuteable (green, C, E). Bar: 10 μm. Wild type clones (B) contain a single large neuroblast, with a crescent of Miranda at metaphase, and a cluster of smaller Miranda negative progeny. Note that the CD8::GFP membrane marker outlines the mitotic spindle (arrowheads). (C) The apical and basal markers Inscuteable and Miranda are localized to opposite poles of third instar metaphase neuroblasts, while crescents of Prospero are seen in most neuroblasts (D); note that the neuroblast Pros staining is weaker than the nuclear staining in neighbouring cells. In contrast to embryonic neuroblasts, Miranda does not colocalize with Inscuteable in early prophase but rather is found both in the cytosol and in a cortical crescent at the opposite pole of the cell to Inscuteable (E).