Figure 4.—

The In∷Mwh fusion protein provides both in and mwh rescue activity. The same region of the dorsal surface of the wing is shown in all images with one exception (D). This region is in the proximal part of the most anterior region of the wing (triple-row bristles are shown). Cells in this (and other) regions of an Ore-R (wt) wing (A) form a single distally pointing hair. In in (B) and mwh (C) mutant wings the hairs point toward the anterior margin and most cells form multiple hairs. The phenotype of mwh in double mutants is indistinguishable from mwh. D shows the ventral surface of a mwh in double mutant wing. H shows the dorsal surface of this wing. In the absence of a Gal4 driver we do not see substantial rescue by the fusion protein (E); however, in the presence of the actin-Gal4 driver we see essentially complete rescue of a null in allele (in^IH56) (F) and almost complete rescue of a null mwh allele (mwh¹) (G). Strong rescue of cells on the dorsal surface of a null mwh in double mutant wing is seen when expression is driven by ap-Gal4. As expected there, this rescue is not seen on the ventral surface of the same wing (D). Arrows point to cells in G that formed more than one hair.