Fig. 7. Effect of bHLH activator transgene expression on bristle production in the absence of endogenous ac and sc. Adult nota of flies carrying pnr-Gal4. (A-E) Wild type for the X chromosome. (F-J) sc^10-1/Y results in a bald notum except for the central pnr-Gal4 domain, whenever sensory organ-inducing bHLH proteins were expressed. Effector transgenes expressed are as follows. (A,F) none. (B,G) UAS-sc. Sc expression induces bristles within the pnr-Gal4 domain. (C,H) UAS-E(spl)m7VP16. Bristles are induced even in the absence of ac and sc. (D,I) UAS-E(spl)m7KNEQ-VP16. Excess bristles are induced only in the ac⁺ sc⁺ background. (E,J) UAS-E(spl)mVP16. Bristles are induced even in the absence of ac and sc.