Fig. 2

Loss of tutl in R cells disrupts the extension of WG processes in the optic lobe. a-d Third-instar eye discs were double-stained with anti-Elav (green) and anti-Tutl (magenta). Anti-Elav antibody recognizes the neuronal-specific nuclear protein Elav that is expressed in all differentiating R cells. Anterior is up. a and c In wild type, differentiating R-cell nuclei were observed in the posterior region of the eye disc. b and d In tutl ²³ eye-specific mosaic individuals, R-cell differentiation occurred normally. Homozygous tutl mutant tissues were identified by lack of anti-Tutl staining. e-j Third-instar eye-brain complexes were double-stained with mCD8-GFP (green) and MAb 24B10 (red). e and h In wild type, WG in the subretinal region project processes (arrow) that follow R-cell axons from the eye disc through the optic stalk (os) into the lamina (la). f and i In homozygous bdl ^EX2 mutants, much less and shorter WG glial processes followed R-cell axons into the lamina. g and j In tutl ²³ eye-specific mosaic individuals in which tutl was specifically removed in R cells, but not in WG, a bdl-like WG extension phenotype was observed. Note that R-cell axons projected normally into the optic lobe in tutl mosaic individuals (j). k The length of individual WG extension within lamina was measured. Loss of tutl in R cells significantly affected the extension of WG processes (p < 0.001). Two-tailed t-tests were used. Error bars indicate SEM. Abbreviations: ed, eye disc; os, optic stalk; la, lamina; me, medulla. Number of individuals examined: wild type, 9; tutl eye-mosaic, 10. Scale bar: a-d, 10 μm; e-i, 20 μm