Fig. 4. Requirement of Notch signaling for primary pigment-cell specification. (A-C) Pupal eye discs stained for Bar. Bar expression in seen in the primary pigment cells (A) and is lost in N^ts pupal eye discs shifted to a non-permissive temperature 10 hours after pupation (B) or when UAS-Su(H)^DN is expressed in the pigment cells using the pigment-cell-specific driver 54C-Gal4 in pupal eye discs (C). (D-F) Wild-type cut expression in pupal cone cells (D) remains unchanged in N^ts when shifted to a nonpermissive temperature 10 hours after pupation (E) or in an 54C-Gal4 UAS-Su(H)^DN background (F). (G-J) Overexpression of Delta in pupal cone cells using the spa-Gal4, UAS-Delta (UAS-Dl) combination causes ectopic primary pigment-cell specification; a high level of expression of the Delta protein is shown (G, compare with Fig. 1B). (H) Wild-type pupal eye disc stained for Dlg to mark the membranes shows four cone cells and a single row of pigment cells between ommatidia. (I) spa-Gal4, UAS-Dl pupal eye disc stained for Dlg show multiple rows of cells between ommatidia (arrow). (J) spa-Gal4, UAS-Dl pupal eye disc stained for Bar show the over specification of Bar-positive primary pigment cells.