Insertion of P element enhancer trap in the 5' untranslated leader of the ap mRNA.
Flies expressing fngScer\UAS.cKa under the control of Scer\GAL4ap-md544 in a aprK568/apmd544 background have ventralised halteres. In addition, the halteres form dark-pigmented bristles that are similar to those formed at the wing margin.
A sharp boundary between dorsal and ventral cells is restored in aprK568/apmd544 wing discs expressing fngScer\UAS.cKa under the control of Scer\GAL4ap-md544. No violations of the compartment boundary are seen. The resulting adult flies have wings of roughly normal size with clearly demarcated wing margin. The rescued wing margin is ventralised; dorsal-specific sensory bristles are completely missing along the anterior margin and cells on both sides of the margin secrete ventral bristle types. The dorsal and ventral wing surfaces are not adhered to each other, resulting in a balloon-like structure. aprK568/apmd544 flies expressing fngEP3082 under the control of Scer\GAL4ap-md544 have wing margin defects.