Fly stocks used

The Antp-eGFP MiMIC line was a kind gift from Hugo J. Bellen (HHMI - Baylor College of Medicine, Duncan Neurological Research Institute Houston, TX, USA; Bloomington Drosophila Stock Center, 59790). The atonal (VDRC ID 318959), brinker (VDRC ID 318246), spalt major (VDRC ID 318068), yorkie (VDRC ID 318237), senseless (VDRC ID 318017) and Sex combs reduced (VDRC ID 318441) fosmid lines are available from the Vienna Drosophila Resource Center (VDRC) and were generated recently in our laboratory (Sarov et al., 2016). The fork head (stock 43951), grainy head (stock 42272), Abdominal B (stock 38625), eyeless, (stock 42271), spineless (transcript variant A, stock 42289) and grain (stock 58483) tagged BACs were generated by Rebecca Spokony and Kevin P. White (Department of Human Genetics, The University of Chicago, IL, USA) and are available at the Bloomington Stock Center. For the scalloped gene, a GFP-trap line was used (Buszczak et al., 2007), a kind gift from Allan C. Spradling's laboratory (line CA07575), with which genome-wide chromatin immunoprecipitation experiments have been performed (Slattery et al., 2013). For the spineless gene, Bloomington stock 42676, which tags isoforms C and D of the Spineless protein, has been also tried in fluorescence imaging and FCS experiments, but did not yield detectable fluorescence in the antennal disc, rendering it inappropriate for use in our analysis. Therefore, we used stock 42289, which tags the A isoform of theprotein. For the eyeless gene, the FlyFos015860(pRedFlp-Hgr)(ey13630::2XTY1-SGFP-V5-preTEV-BLRP-3XFLAG)dFRT line (VDRC ID 318018) has been tried also in fluorescence imaging and FCS experiments, but did not yield detectable fluorescence in the eye disc for it to be used in our analysis. The act5C-FRT-yellow-FRT-Gal4 (Ay-Gal4) line used for clonal overexpression or RNAi knockdown has been described (Ito et al., 1997). The UAS-Antp lines (synthetic and full-length), as well as UAS-SynthScr constructs, have been previously described (Papadopoulos et al., 2011, 2010). The Dll-Gal4 (MD23) line was a kind gift from Ginés Morata (CBMSO, Universidad Autónoma de Madrid, Spain) (Calleja et al., 1996). 69B-Gal4 and ptc-Gal4 were obtained from the Bloomington Stock Center. The Antp P1-lacZ and P2-lacZ have been previously described (Engstrom et al., 1992; Zink et al., 1991). The P1 reporter construct spans the region between 9.4 kb upstream of the P1 promoter transcription initiation site and 7.8 kb downstream into the first intron, including the first exon sequences and thus comprising 17.2 kb of Antp regulatory sequences (pAPT 1.8). The line used was an insertion of the pAPT 1.8 vector bearing the P1 promoter regulatory sequences upstream of an actin-lacZ cytoplasmic reporter and was inserted in cytogenetic location 99F on the right chromosomal arm of chromosome 3. The Antp-RNAi line was from VDRC, line {"type":"entrez-nucleotide","attrs":{"text":"KK101774","term_id":"761968461","term_text":"KK101774"}}KK101774. UAS-eGFP stock was a kind gift from Konrad Basler (Universität Zürich, Switzerland). We are indebted to Sebastian Dunst (Max-Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany) for generating the ubi-FRT-mCherry(stop)-FRT-Gal4(VK37)/CyO line, which drives clonal overexpression upon flippase excision, while simultaneously marking cells by the loss of mCherry. For red-color labeling of clones the act5C-FRT-CD2-FRT-Gal4, UAS-mRFP1 (NLS)/TM3 stock 30558 from the Bloomington Stock Center was used. For marking the ectopic expression domain of untagged Antp proteins, the UAS-mRFP1(NLS)/TM3 stock 31417 from the Bloomington Stock Center was used. The MS243-Gal4; UAS-GFP/CyO line was a kind gift from the laboratory of Ernesto Sánchez-Herrero (CBMSO, Universidad Autónoma de Madrid, Spain).