Fig. 2. Expression of the SOP markers neur^A101-lacZ, Sens and Hnt in Notch mutant cell clones as well as in Psn, Su(H) and kuz mutant wing imaginal discs. Expression of the SOP marker is detected by antibody staining. Alleles used in this analysis are: Df(1)N^81K, Psn^C1, Su(H)⁴⁷ and the combination kuz¹⁴⁰⁵/kuz¹⁴⁰³. They are amorphic or strong alleles of the corresponding genes. Anterior is towards the left, ventral towards the bottom. (A-D) neur^A101-lazZ expression. The wing disc shown in A is also stained with an anti Wg antibody to visualize the expression of Wg (red). neur^A101-lacZ expression in A is shown in green. The arrows indicate the SOPs that have formed. (E-I) Expression of Sens. (J-N) Expression of Hnt. (A,E,J) Expression of neur^A101-lacZ, Sens and Hnt in wild-type wing imaginal discs of the late third larval instar stage. (B,F,K) Wing imaginal bearing Notch mutant clones that are labelled by the absence of the green GFP marker. Expression of the corresponding SOP marker is shown in red. (G,L) Psn^C1 mutant wing imaginal discs. (C,H,M) Su(H)⁴⁷ mutant wing imaginal discs. (D,I,N) kuz¹⁴⁰⁵/kuz¹⁴⁰³ mutant wing imaginal discs. In the wild type, neur^A101-lacZ, Sens and Hnt are expressed in all SOPs of the wing imaginal disc. Sens is also expressed in cells along the wing margin (wm in E). Arrows in A indicate the position of each individual SOP. The figure reveals that cells of all proneural clusters in the notum that are mutant for Notch, Psn or kuz express the three SOP markers (arrows in F-I,K-N). The situation is different in Su(H) mutants: only a few cells of the DC, the ANP and ANP cluster weakly express neur^A101-lacZ (arrows). Moreover, expression of Sens (H) and Hnt (M) is lost in almost all cells of the notal clusters. We occasionally found weak expression of Sens in some cells of the ANP and PNP cluster (arrow).