Fig. 2.

Essential and dose-dependent Mam functions in FSCs. (A-D) Ovarioles with FSC clones marked by the absence of (green) nuclear Ubi-GFP or tub-lacZ gene product (`Bgal') and stained with FasIII (red). Clones were induced in adults and evaluated 14 days after induction. (A) A typical control (wild-type) FSC clone includes a FSC (arrow) just anterior to FasIII-staining cells and numerous FSC derivatives (arrowheads). (B) An `all marked' ptc^S2 mutant ovariole. All FSCs and FSC progeny are mutant as indicated by lack of GFP expression. All germline cells retain GFP expression in this ovariole. (C) A mam⁸ mutant FSC clone has lost the mutant FSC, as no somatic cells in the germarium lack tub-lacZ expression, but retained FSC derivatives (arrowheads). Several mam mutant cells lie between adjacent fused egg chambers. Arrow marks normal FasIII staining in wild-type polar cells at the posterior of the egg chamber. (D) ptc^S2 mam⁸ FSC derivatives (arrowheads) lie between the germarium and successive fused egg chambers. (E-J) Ovarioles containing FSC clones positively marked with GFP (green) and stained with FasIII (red). (E) Wild-type FSC clone with a FSC (arrow) and its derivatives (arrowheads). (F) An `all marked' ptc<sup>S2</sup> mutant ovariole, with multiple ptc mutant FSCs (arrows). (G) A mam<sup>8</sup> mutant FSC clone includes FSC derivatives (arrowhead) but no FSC. (H) A ptc<sup>S2</sup> mam<sup>8</sup> mutant FSC clone has lost the FSC but derivatives (arrowheads) separate fused egg chambers. (I) High-level expression of UAS-Mam in a ptc<sup>S2</sup> mam<sup>8</sup> FSC clone produces multiple FSCs (arrows) giving rise to an `all marked' ovariole. (J) Low-level UAS-Mam expression in ptc^S2 mam⁸ FSC clones results in a single mutant FSC (arrow) in ovarioles that retain a morphology that is close to normal.