Fig. 3. Synergistic interaction between ed and the N pathway. (A-C) Nota of flies expressing in proneural clusters (C253-Gal4 driver) either UAS-ed^ECD (abbreviated ed^DN) (A), UAS-N^DN (B), or UAS-N^DN plus UAS-ed^ECD (C). Note the strongly enhanced neurogenic phenotype in C: the replacement of extant macrochaetae by tufts of bristles (arrowheads) and the loss of many macro and most microchaetae. (D) Notal dorsocentral region of a C253; UAS-N^DN; UAS-ed^ECD pupa stained with 22C10 antibody. Clusters of neurons appear at the sites of the developing sensory organs, as a result of the loss of N signaling, which leads to the differentiation of the descendants of the pIIa precursor cells as extra neurons. In the wild type, only a single neuron innervates each notum bristle. Inset depicts part of the third instar notum region of a C253; UAS-N^DN; UAS-ed^ECD larva stained with anti Sens antibody. Note the large clusters of SOPs at the DC and NP positions. (E,F) Nota of N^55e11 (E) and N^55e11; ed^1x5/ed^slH8 flies (F). Similar to C, the simultaneous decrease of N and ed functions increases the neurogenic phenotype manifested by the almost complete absence of microchaetae (compare with ed^1x5/ed^slH8 notum, Fig. 1B). (G-I) Nota of flies expressing in proneural clusters (sca-Gal4 driver) either UAS-ed^ECD (G), UAS-Dl^DN (H) or UAS-Dl^DN plus UAS-ed^ECD (I). The neurogenic phenotype caused by a decrease of Dl function is potentiated by the simultaneous decrease of ed function, resulting in large tufts of macrochaetae and increased density of microchaetae.