Fig. 4. msh downregulates ara/caup in the hinge territory. Red: accumulation of Ara/Caup. (A) Wild-type disc. The notum Ara/Caup domain (arrow) is widely separated (white line) from the Nub (blue) wing pouch domain. (B) Disc harboring large msh⁶⁸ M⁺ clones (absence of green). The notal Ara/Caup domain reaches almost to the wing pouch (arrowhead). Asterisks indicate the area incapable of expressing ara/caup. (C) Small msh⁶⁸ clones (absence of green), induced 48/72 hours AEL, autonomously derepress ara/caup at the presumptive hinge, except when located (arrowhead) in the area shown in B (asterisk). (D) Disc overexpressing UAS-mshi driven by ap-Gal4. Msh almost completely disappears from the dorsal hinge (d) and Ara/Caup accumulates there. A slightly convex line joining the arrowheads would approximately demarcate the notum/dorsal-hinge border. Arrow indicates presumptive ventral hinge and pleura with unmodified msh and ara/caup expressions. (E) Clone overexpressing UAS-msh (green, GFP marker, induced at 12-36 hours AEL) removed or strongly inhibited notal Ara/Caup accumulation (arrowhead). (F) Drawing of a series of non-Minute msh⁶⁸ clones reveals the areas (purple) competent to express ara/caup. (G) Early overexpression of UAS-msh, ap-Gal4 driver at 25°C (green, UAS-GFP marker) interfered with the growth of the notum territory (arrowhead; compare with wild-type disc in A, arrow). ara/caup expression always persisted in the proximal-most part of the notum territory, a result similarly observed with clones expressing UAS-msh in this location (text). This suggests that Iro-C is differentially controlled in different regions of the notum.