Figure 1. Wingless signalling activates expression of Odd skipped in the proximal tubule.
(A) Diagram to indicate organisation of the anterior and posterior Malpighian tubule pairs in the embryo, which emanate from the gut at the midgut-hindgut junction. Wild-type expression domains of Cut (magenta) and Odd (green) are indicated. B-E show maximum intensity projections of approximately stage 16 Drosophila embryos, oriented anterior left, stained with anti-Cut to mark the entire tubule and anti-Odd to highlight the proximal tubule. Arrowheads mark the distal extent of the Odd-expressing domain in the tubule. Asterisks indicating Odd expression in posterior midgut. An enlargement of the Odd-expression domain in the anterior tubule corresponding to boxed region is provided (right panel). Note that not all tubules may be visible due to orientation. (B) Control (w1118) embryo showing Odd staining in the nuclei of both ureters at the proximal end of the Malpighian tubules (arrows indicate tubules). (C) Embryo in which dominant negative pangolin/dTCF-∆N (pan/dTCF-∆N) is expressed in tubules under control of the cut promoter, to inhibit Wg signalling. (D) Embryo in which constitutively active armadilloS10 (armS10) is expressed in tubules under control of the cut promoter, to activate Wg signalling. (E) A wg temperature sensitive mutant (homozygous wg1-12), switched to the restrictive temperature during later stages of tubule development (see Materials and methods for timings). Arrows indicate the Malpighian tubules (displaying somewhat abnormal morphology) which show no clear anti-Odd staining. Scale bar = 50 μm.
Figure 1—figure supplement 1. Odd expression in proximal tubule is normal upon loss of zygotic Caudal.
