Figure 3

RN-tre is the corresponding gene of the GSd427 and UY333 misexpression phenotype. (A) An EMS mutagenesis screen for identifying the suppressors of the GSd427 gain-of-function eye phenotype. Males carrying the GSd427-containing chromosome were mutagenized by EMS ingestion and then crossed with females carrying GMR-GAL4. The F1 progeny were screened for the suppression of the reduced eye phenotype. (B) Sequencing of the RN-tre gene in one suppressor (GSV) allele reveals a non-sense point mutation at nucleotide 1119 that converts the codon for Trp into a stop codon at amino-acid 287. (C-H) Longitudinal optic sectioning of third-instar eye discs double-stained with anti-Elav (blue) and MAb 24B10 (Chaoptin) (red) antibodies to visualize R-cell nuclei and R-cell surface, respectively. (C, E and G) Wild-type eye discs show apical localization of R cells. (D, F and H) Misexpression of UAS-RN-tre under control of GMR-GAL4 induced basal localization of R cells (D, F, H, arrowheads) (~32%, n = 1008 ommatidia in 6 eye discs). Scale bar: 10 μm.