How to pattern an epithelium: lessons from achaete-scute regulation on the notum of Drosophila

The zebrafish Iroquois geneiro7positions the r4/r5 boundary and controls neurogenesis in the rostral hindbrain

“…This dual function is consistent with the successive roles found for Iro genes in the Drosophila wing imaginal disc Leyns et al, 1996;Grillenzoni et al, 1998;Diez del Corral et al, 1999;Calleja et al, 2002). Like its Drosophila cognate genes, iro7 is required for successive steps of the patterning of an embryonic territory.…”

A Screen for Modifiers of Notch Signaling Uncovers Amun, a Protein With a Critical Role in Sensory Organ Development

“…The following strains were used for the study of CG2446 (Amun): eyeless (ey)-Gal4 (Bose et al 2006) (Bloomington Drosophila Stock Center); decapentaplegic (dpp)-Gal4/TM6B (StaehlingHampton et al 1994); pannier (pnr)-Gal4/TM3 (Heitzler et al 1996), a gift from Gines Morata, Centro de Biología Molecular Severo Ochoa (Madrid); patched (ptc)-Gal4 (Speicher et al 1994) (Bloomington Drosophila Stock Center); scabrous (sca)-Gal4/CyO (Mlodzik et al 1990), a gift from Andrea Brand, University of Cambridge (Cambridge, UK); UAS-myr-mRFP/ TM6B (Bloomington Drosophila Stock Center); stripe MD710 (sr)-Gal4/TM6B (Calleja et al 2002;Usui et al 2004), a gift from Pat Simpson, University of Cambridge (Cambridge, UK); UASAmunRNAi and UAS-Dicer2 (Dietzl et al 2007), obtained from the Vienna Drosophila RNAi Center; and P[lArB]A101.IF3 (neur A101 -LacZ)/TM3 (Bellen et al 1989), a gift of Hugo Bellen, Baylor College of Medicine (Houston).…”

“…Reduction of Amun levels under control of the sca-Gal4 or ptc-Gal4 driver results in multiple bristle defects including missing, supernumerary, and misplaced macrochaetae, as well as probable shaft-to-socket transformations ( Figure 6, E and F, respectively). Reduction of Amun under control of sr-Gal4 (a transgene that drives expression in a subset of microchaeta rows in the medial and lateral notum; Calleja et al 2002) and pnrGal4 (a P-element insertion in the pnr gene that drives expression in the 10 medial microchaeta stripes; Heitzler et al 1996) results in disorganized and smaller microchaetae ( Figure 6, G and H, respectively). Importantly, as shown in Figure 6I, co-overexpression of AmunTRFP with AmunRNAi rescues the loss-of-function phenotypes shown in Figure 6H, suggesting that the AmunRNAi phenotype results from specific reduction of endogenous Amun function.…”

Opposing inputs by Hedgehog and Brinker define a stripe ofhairyexpression in theDrosophilaleg imaginal disc

“…Extensive studies on the development of sensory structures in the Drosophila mesothorax and other tissues have shown that the redundant proneural genes, ac and sc, function at a local level to confer neural competence to cells destined to become sensory organs (SOs) (Calleja et al, 2002;Modolell, 1997). The bHLH transcription factors, Ac and Sc, are expressed in proneural clusters, groups of cells that roughly define the positions of future sensory structures in the adult (Cubas et al, 1991;Romani et al, 1989;Skeath and Carroll, 1991).…”

“…The bHLH transcription factors, Ac and Sc, are expressed in proneural clusters, groups of cells that roughly define the positions of future sensory structures in the adult (Cubas et al, 1991;Romani et al, 1989;Skeath and Carroll, 1991). Then, through local regulatory events controlled by the neurogenic genes, a cell(s) is selected from each proneural cluster to become a sensory organ precursor, which undergoes a few differential cell divisions (Calleja et al, 2002;Modolell, 1997). The resulting cells give rise to the components of the SO.…”