Fig. 2. Sxl allows Hh with only cholesterol modification to stabilize Ci. (A-F) Discs expressing Hh with only the cholesterol modification, C84S-Hh, with dpp-GAL4 driver stained for Ci (red) and Sxl (green). dpp is expressed in a broad band in the anterior compartment, a few cells away from the AP boundary – see dpp-lacZ staining in Fig. 6A. Both male and female discs were treated with 50 ng/ml LMB for 3 hours, and scanned at about the same laser intensity. (A-C) Male disc; (D-F) female disc. In males, as previously reported (Lee et al., 2001), the levels of Ci fall (arrowhead in A for example). For females, the amount of LMB is about one-third of that needed in wild-type discs to detect nuclear, full-length Ci in region around dpp expression zone (e.g. arrowhead in D); Sxl is also nuclear (arrows in E, F). Insets in A,C enlarge the area indicated by arrowheads; inset in E enlarges the area indicated by an arrow. (G-L) Discs expressing Sxl and C84S-Hh with dpp-GAL4 driver stained for Ci (red) and En (green). (G-I) Male disc; (J-L) female disc. Ci signal is punctate (e.g. G) and En-positive cells extend towards the anterior compartment (arrow in H), which was seen in all male discs (n>12) of this genotype (non-Tubby larvae). Inset in G enlarges the area indicated by an arrowhead. Male discs were treated with 50 ng/ml LMB for 3 hours; female discs were treated with half the amount of LMB. The size of the nuclei and scale bars in I,L both illustrate that the female disc is larger than the male. Punctate signal is indicative of nuclear Ci and there is a relative increase in size of the anterior compartment (bracket in L). Scale bars: in C, 20 µm for A-C; in F, 20 µm for D-F; in I, 20 µm for G-I; in L, 20 µm for J-L. For all discs, anterior is towards the left, ventral is towards the top. Confocal images throughout.