Figure 8

Vari function in the developing eye. (A, A') Third instar wild-type eye imaginal discs stained with anti-Vari (green). Vari is predominantly expressed behind the morphogenetic furrow (white arrow in A) in the developing ommatidia. The close-up view on ommatidia of the 4-cone cell stage (A') demonstrates that Vari localises to the lateral membranes of the photoreceptor and cone cells. (B, B') Close-up views of ommatidia, stained with antibodies against Cora (B, green) and NrxIV (B', red), respectively. Cora and NrxIV are expressed in the photoreceptor and cone cells. (C-C') Head of a wild-type fly (C) and a fly overexpressing vari-RNAi with eyGal4 (C'). Reduction of vari induces roughening, downsizing and malformation of the eye. (D-D') Eye imaginal discs of third instar wild-type larvae (D) and larvae overexpressing vari-RNAi with eyGal4 (D'), stained with anti-Futsch/22C10 antibody to mark the photoreceptor cells. Reduction of vari function (D') leads to aberrant folding of the eye imaginal disc and additional tissue formation at the antennal disc (arrow). Black arrowheads mark the position of the morphogenetic furrow in D. bw = Bolwig's nerve, ad = antennal disc, ed = eye disc. (E-E") X-Gal staining of eyGal4; Gbe+Su(H)lacZ (E) and eyGal4; Gbe+Su(H)lacZ>UAS vari-RNAi (E') third instar eye imaginal discs to visualize activity of the Notch signaling pathway. Despite morphological aberrations Notch activity does not seem to be strikingly affected by RNAi-mediated knockdown of vari. eyGal4; Gbe+Su(H)lacZ>UAS vari-RNAi eye imaginal discs from second instar larvae already display abnormal folding (E", arrow). The eye imaginal disc in E" is shown in a higher magnification than those in E and E'. (F, F') Semi-thin sections of eyes from wild-type flies (F) and flies overexpressing vari-RNAi with eyGal4 (F'). In ommatidia with reduced vari function (F') the seven photoreceptor cells visible do not exhibit major morphogenetic defects and are still organised in a trapezoid pattern as in wild-type (F). In A, D and E anterior is left.