Fig. 1

Tutl is expressed in R cells in the developing visual system at third-instar larval stage. Longitudinal optic sections of wild-type (a-d) and tutl-eye mosaic (e-h) third-instar eye discs were triple-stained. Tutl immunoreactivity was detected with a rabbit anti-Tutl antibody (red). WG processes were visualized with UAS-mCD8-GFP driven by the WG-specific Mz97-GAL4 (i.e. Mz97-GFP) (green). R-cell bodies and their axons were labeled with anti-HRP (b) or MAb24B10 (f) (blue). Apical is up, and posterior is to the right. a In wild type, Tutl immunoreactivity was detected in R-cell bodies and axons in the eye epithelium as well as subretinal regions where R-cell axons migrate posteriorly towards the optic stalk. b All R-cell bodies and axons in a were visualized with anti-HRP staining. c WG processes in a were labeled with Mz97-GFP. WG processes at the subretinal region follow R-cell axons and migrate posteriorly. d Images in a-c were merged. (e-h) Large clones of homozygous tutl ²³ mutant eye tissues were generated with eye-specific mitotic recombination. Thus, the tutl gene was specifically removed in mutant eye clones, but not removed in WG. e Anti-Tutl staining. Tutl immunoreactivity was absent in mutant R-cell bodies and axons. At subretinal regions where tutl mutant R-cell axons associate with WG processes, Tutl immunoreactivity was also missing. f All R-cell bodies and axons in e were labeled with MAb24B10 staining. g WG processes in e were labeled with Mz97-GFP. h Images in e-g were merged. Scale bar: 10 μm