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. 2014 Dec 4;9(12):e114340. doi: 10.1371/journal.pone.0114340

Figure 1. An assay to identify genes required to maintain the straight shape of the AP boundary.

Figure 1

A. Scheme of tester stock and cross to generate clones of cell expressing double-stranded RNA. The tester stock contains a Flp recombinase transgene under control of the heat-shock inducible promoter hsp70 (hs) on chromosome I [36] and the engrailed-Venus transgene on chromosome II (not shown). Chromosome III contains a transgene composed of the Act5C promoter followed by a FRT site, the coding sequence for the mouse transmembrane protein CD2 followed by a transcriptional terminator (Term), a second FRT site, and finally Gal4. We have recombined on the same chromosome a transgene expressing DsRed under control of UAS sequences (not shown). The tester stock is crossed to individual RNAi fly lines. The resulting progeny larvae are heat-shocked to express the Flp recombinase that in turn induces recombination between the two FRT sites on the tester stock. This recombination places Gal4 under the direct control of the Act5C promoter leading to Gal4 expression specifically in the clones of cells. Gal4 then binds to the UAS sequences in the RNAi line and directs expression of double-stranded RNA that leads to RNA interference. At the same time, Gal4 will induce expression of DsRed (not shown) in the same cells. B. Scheme of the assay. The central part of the wing imaginal disc is schematically drawn as an oval. A Venus fluorescent protein (green) is specifically expressed in all cells of the posterior compartment under control of the promoter sequences of the engrailed gene (en-Venus). Clones of cells expressing double stranded RNA are identified by co-expression of DsRed (red). Examples on the left depict wild-type clones located in the anterior (A) or posterior (P) compartments. Examples on the right depict a anterior clone mis-segregating into the posterior territory (top) and an posterior clone mis-segregating into the anterior territory (bottom) of the wing disc. Clones co-expressing DsRed and Venus are depicted in yellow.