Fig. 1

A fraction of Notch remains at the LM of lgd mutant MEs and is activated. (A, A’) Dx and Su(dx) act antagonistically to determine the fraction of Notch remaining at the LM of the ME. Over-expression of Su(dx) or loss of dx function favours incorporation of Notch into ILVs. (B–C’) Expression of the Notch target Wg and the Notch activity reporter Gbe+Su(H) in wild-type and lgd mutant discs. The expression domain of Wg along the D/V boundary of the wing anlage (arrow in B) is dramatically expanded in lgd mutant discs (arrow in C). In addition, the complex expression pattern of Gbe+Su(H) seen in wild-type is replaced by a uniform staining in the mutant discs (B’, C’). (D, D’) Over-expression of Su(dx) with hhGal4 in the posterior compartment normalises the expression of both read-outs of Notch activity (arrow). A similar effect is seen if the function of dx is removed in lgd mutant discs (E, E’, arrow). Note that the normal expression of the Notch targets, e.g. along the D/V boundary (arrow in D–E’), is not affected by the manipulations. Scale bars (B–E’) 200 μm. At least ten wing imaginal discs were analysed for each genotype