Fig. 2. Accumulation of Sc, Sens and E(spl)-m8 mRNA in wild-type (A,C) and C253-Gal4; UAS-ed^ECD/UAS-ed^ECD (B,D) wing discs. (A,B) Notum regions showing that the levels of Sc protein in proneural clusters (green) are not significantly modified, except for the presence of extra SOPs in the disc expressing UAS-ed^ECD (B). These also accumulate Sens protein (red channel), as shown in magnified images (insets) of the anterior and posterior notopleural (ANP, PNP) and dorsocentral (DC) proneural clusters. As many extra SOPs develop late, their accumulation of Sens is lower than that of earlier emerging SOPs. (C,D) Expression of E(spl)-m8 is decreased in the proneural clusters of discs expressing the Ed dominant-negative protein. Images show representative discs from a sample of 41 wild-type and 22 UAS-ed^ECD-expressing discs. (E) Notum from a fly with the same genotype (C253-Gal4; UAS-ed^ECD/UAS-ed^ECD) of the discs shown in B and D. Note the increased number of macrochaetae arising from proneural clusters (compare with Fig. 1A). (F) Physical structure of Ed derivatives overexpressed in UAS constructs. Ed contains the extracellular and transmembrane (TM, red) domains, followed by the 315 amino acid intracellular domain. Ed^intra only contains the intracellular domain. Ed^ECD lacks the extracellular domain but contains the TM and intracellular domain. Ed^ECD-48 and Ed^ECD-124 are similar to Ed^ECD but lack the C-terminal 48 and 124 amino acids, respectively. As overexpressed with either ap-Gal4, sca-Gal4 or C253-Gal4, only UAS-ed^ECD exhibited ectopic macrochaetae and increased density of microchaetae, and is referred as a dominant negative (DN). Overexpression of the rest of UAS constructs had no effect on bristle pattern (–).