Fig. 7. Permanent repression of the engrailed gene induced by high Engrailed levels. (A-C) Posterior to anterior transformations in the mesonotum (A) and wing (B) of en-Gal4/UAS-en flies. See the duplicated notum (arrow in A) and the presence of anterior bristles in the posterior wing (C, detail of the square in B). A and P indicate anterior and posterior, respectively. (D) En expression in a wild-type wing disc. (E) En expression in an en-Gal4/UAS-en wing disc is confined to small groups of cells and the posterior compartment is enlarged. (F,G) GFP (F) and En (G) expression in an en-Gal4 UAS-GFP/+; UAS-en/+ wing disc is coincidentally repressed. (H-K) ap-Gal4 UASGFP/en-lacZ; UAS-en/tub-Gal80^ts wing disc from larvae grown for 5 days at 29°C and transferred to 17°C for 3 days. GFP signal (H, green) is still present (though reduced) in the apterous (dorsal) domain of the disc, and both En (I, in red) and β-galactosidase (J, greyscale) expression disappear in the posterior dorsal compartment (arrows). There is ectopic β-galactosidase signal in the dorsoventral boundary (arrowhead in J). Merged image in K. d and v indicate dorsal and ventral compartments, respectively. Discs are oriented with the anterior compartment towards the left and the ventral compartment upwards.