Fig. 3
HisCl1 but not Ort is expressed in photoreceptors. a–d Expression of HisCl1-gal4 UAS-mCD8-gfp, detected with anti-GFP antibody (green); photoreceptors are marked with anti-Chaoptin antibody (red). HisCl1 expression is detected in the lamina epithelial cells and very faintly in the eyelet (a, b). Weak labeling is observed in some R7 and R8 photoreceptors axons in the medulla (c, d). e–g Expression of GFP-tagged HisCl1 protein expressed from the HisCl1 promoter detected with anti-GFP antibody (green); photoreceptors are marked with ey-rfp from the same fosmid construct (red). HisCl1::GFP is detected in the lamina (e), H-B eyelet (e, g), and both in the R7 (f) and R8 (g) photoreceptors, identified by their respective position in the retina (arrows), upper layer for R7 and lower layer for R8. h–m HisCl1 (h-k) and ort (l, m) mRNA expression (blue) visualized by RNAscope® in situ hybridization (ISH) (see Methods). Anti-Rh6 antibody (red) labels yR8 and eyelet photoreceptors in (j, k, m). HisCl1 mRNA in the retina appears as puncta primarily in two layers: proximally, near the R8 photoreceptor nuclei (h pink bracket) and distally, near the R1-7 photoreceptor and other retinal cell nuclei (h yellow bracket). No puncta were detected in the HisCl1134 mutant (i). In the R8 photoreceptor layer HisCl1 mRNA is expressed in the Rh6-positive (red) yR8 retinal photoreceptors, as well as in the surrounding cells that likely include Rh5-expressing pR8 photoreceptors (j). HisCl1 mRNA is also present in the Rh6-expressing H-B eyelet (k). ort mRNA is expressed in the lamina but not in the retina (l, m). In particular, ort is undetectable in the Rh6-expressing cells (red in m) both in the retina (outlined in l, m) and in the eyelet. In (h, i), the retinas are surrounded by the autofluorescent cuticle. Images in (h–m) are maximal projections of short confocal stacks (thickness: 10 (h, i), 12 (j, k), 13.5 (l-m) µm). La lamina, Me medulla, Re retina. White arrows point to the H-B eyelet. Scale bars represent 20 (a–i), 10 (j, k), and 50 (l, m) µm
