Fig. 6. The dominant-negative activity of EdExt is modulated by the Notch signaling pathway. (A-D) SEM of anterior midline region of adult thorax. (A) Normal microchaetae distribution in wild type (WT) flies. Ectopic expression of EdExt mediated by Eq-GAL4 driver results in a mild increase in the microchaetae density (B). Ectopic expression of Dl also results in an increased microchaetae density (C). (D) UASEdExt/+; UAS-Dl/Eq-GAL4 flies show significantly increased microchaetae density. (E) Arrangement of sensory bristles on the notum of an UAS-EdExt/+ fly. An extra bristle can be seen rarely. pnr-GAL4-mediated ectopic expression of EdExt results in formation of extra bristles, which is accompanied by loss of epidermis (F). Overexpression of E(spl)m7 results in suppression of sensory bristle formation, resulting in a bald mesothorax region (G). Overexpression of E(spl)m7 completely suppresses the phenotype of EdExt overexpression (H). Thus UAS-EdExt/+; UAS-E(spl)m7/pnr-GAL4 flies (H) are indistinguishable from UAS-E(spl)m7/pnr-GAL4 flies (G).