Fig. 4. Pygo acts downstream or in parallel with Arm to regulate nuclear Arm activity. An embryo lacking both maternal and zygotic axin exhibits the characteristic naked cuticle phenotype associated with constitutive Wg signaling (A). In a axin-pygo^F15 double null embryo, the naked cuticle phenotype is reversed and exhibits a ‘lawn’ of denticles phenotype (B). A wing bearing somatic clones of axin produced by vg Q1206-Gal4/UAS flipase, is shown in C. Numerous bristles were produced by clones mutant for axin (C). A wing with axin-pygo^F15 somatic clones (D) exhibits no bristle within the wing and produces notching and the formation of ectopic bristles in nearby tissues, which is similar to the wing bearing pygo^F15 clones (see Fig. 1B,C). A axin somatic clone in the wing disc produces autonomously the expression of Ac (E,E'). In a axin-pygo^F15 somatic clone, no induction of Ac expression is observed (F,F'). In a wild-type embryo, Arm protein levels are upregulated in a segmentally repeated fashion in the ventral ectoderm (G). The expression of Arm protein remains in a segmentally repeated fashion in embryos mutant for pygo (H). In a wing disc, Arm protein is strikingly upregulated in a clone mutant for axin (I,I',I''). This upregulated Arm protein is not diminished in clones mutant for axin-pygo (J,J',J''). There is no difference in the subcellular localization of Arm protein in clones of axin and axin-pygo (compare I,I',I'' with J,J',J'').

Return to article