Fig. 1. The EP(33-077), EP(44-004) and EP(34-165) suppression of the rough eye phenotype when Sev RTK signaling is activated. (A) Rough eye phenotype caused by the constitutively activated Sev receptor (sev^S11/+). (B) Suppression of the rough eye phenotype due to the overexpression of a double-headed EP line identified in the screen (sev-Gal4 sev^S11/EP). Note that the regular pattern of ommatidia is rescued. (C) The double-headed EP transposable element, showing the 5' and 3' UAS sites (black arrowheads). Activation of the Gal4 drives expression of the genes adjacent to 5' and 3' UAS sites. The loxP sites flanking the 5' UAS (red boxes), will remove the 5' UAS site when in the presence of the recombinase cre. Note that flies lacking the 5' UAS site will be distinguished by the lack of the yellow⁺ marker and named EP(y^-). (D) Summary of the suppression of the Sev^S11 construct by the three EP lines. (E) Genomic region and insertion of EP(33-077), EP(44-004) and EP(34-165). There are three genes in this region: ATPsyn-d, mRpL55 and cdi. Black arrows indicate the transcription starts and orientation of the three genes. The EP(33-077) is 1.800 bp upstream from 5' UTR of mRpL55. They are orientated with the 3' UAS site (small blue arrows) towards the 5' end of cdi and mRpL55. The blue bar represents the 2.077 bp deletion of the cdi^R47 allele. (F) Molecular characterization of the gene expression induced by the EP lines. RT-PCR from hs-Gal4 EP larvae after heat shock induction indicates that both cdi and mRpL55 transcripts are overexpressed. EP(34-165y^-) and EP(44-004y^-) are shown as examples, and rp49 expression as a control. C lanes show expression without heat shock. E lanes show expression after heat shock. (G) Wing disc from en-Gal4/+; EP 34-165/+ larvae stained with an antibody against Cdi. Cdi protein is strongly expressed in the posterior compartment due to EP activation. (H) en-Gal4/UAS-cdi wing discs stained with anti-Cdi show abundant localization of Cdi in the posterior compartment.