Expression of Wnt4Scer\UAS.cGa under the control of Scer\GAL4bap.3 in the visceral mesoderm is sufficient to redirect the salivary glands ventrally, away from the visceral mesoderm. The redirection affects the entire salivary gland.
Expression of Wnt4Scer\UAS.cGa under the control of Scer\GAL4upd-E132 does not result in obvious planar polarity defects in the developing eye discs or adult eyes.
Expression of Wnt4Scer\UAS.cGa under the control of Scer\GAL4bi-omb-Gal4 does not result in any polarity changes in the eye disc.
Flies expressing Wnt4Scer\UAS.cGa under the control of Scer\GAL4dpp.blk1 or Scer\GAL4ptc-559.1 show frequent loss of the anterior crossvein. In addition, there are dramatic hair polarity changes in the distal region of the wing, with wing hairs oriented towards the anterior-posterior boundary between veins L3 and L4.
Expression of Wnt4Scer\UAS.cGa under the control of Scer\GAL4Act5C.PP in clones in the wing results in wing hairs around the clone shifting their polarity towards the clone.
Expression of Wnt4Scer\UAS.cGa under the control of Scer\GAL4ptc-559.1 at 18oC results in flies with outspread wings. Most animals expressing Wnt4Scer\UAS.cGa under the control of Scer\GAL4ptc-559.1 at 29oC until mid-third larval instar and then shifted to 18oC die as pharate adults, but some escapers with small ectopic wings arising from the posterior region of the notum near the boundary between the dorsal and ventral notal structures are seen. Parts of the scutellum are lost in these animals. Animals expressing Wnt4Scer\UAS.cGa under the control of Scer\GAL4ptc-559.1 at 29oC throughout development develop ectopic wings of different sizes. Most of the ectopic wings are small and show hair-like structures characteristic of the alula, but large ectopic wings which arise from both sides of the posterior notum are reproducibly obtained. The ectopic wing is a mirror image duplication of the endogenous wing. The ectopic wing usually has wing margin bristles of posterior identity. Anterior structures such as anterior margin bristles and campaniform sensory neurons are occasionally formed. Occasionally, complete wing duplication is seen, this phenotype being associated with almost complete loss of the notum. Expression of Wnt4Scer\UAS.cGa under the control of Scer\GAL4ptc-559.1 at 29oC induces duplication of the halteres. The bifurcation occurs more or less distally, so that the two resulting appendages are either completely separated, form a common scabellum or have fused pedicels. Wing discs expressing Wnt4Scer\UAS.cGa under the control of Scer\GAL4ptc-559.1 show outgrowth from the posterior region of the notum. Expression of Wnt4Scer\UAS.cGa under the control of Scer\GAL4ptc-559.1 results in extra sternopleural bristles and extra dorsocentral, posterior postalar and scutellar bristles when the scutellum is not transformed into wing.
Expression of Wnt4Scer\UAS.cGa under the control of Scer\GAL4da.G32 has a variable effect on the cells of the dorsal epidermis in the embryo (in wild-type embryos each parasegment contains 4 types of cells in the dorsal epidermis; the 1o, 2o and 3o cells in the anterior half of the parasegment and the 4o cells in the posterior half of the parasegment). When one copy of Wnt4Scer\UAS.cGa is expressed at 29oC, 21% of segments have a 2o-3o-4o pattern, in which 1o cells are missing and 3o cells are expanded. In contrast, 62% of segments show either a 1o-3o-4o or 3o-4o pattern (1o and 3o cells are difficult to distinguish). Lower levels of expression result in a higher percentage of embryos with a pattern that is more clearly 1o-3o-4o along the dorsal midline, since the 2o cell fate is still apparent laterally.
Embryos expressing one copy of Wnt4Scer\UAS.cGa under the control of Scer\GAL4da.G32 show mild but consistent defects consisting of ectopic denticles within the regions of naked cuticle. Posterior segments are more affected than anterior ones and segmentation and diversity of denticle morphology are not entirely lost. Embryos expressing two copies of Wnt4Scer\UAS.cGa under the control of Scer\GAL4da.G32 have stronger phenotypes; the naked cuticle is often completely lost and replaced with denticle decorated cuticle, especially in the most posterior segments.