Figure 3. Synergistic interactions between Med19 and Hox mutations.

Dose-sensitivity for Med19 was tested relative to Hox gain-of-function mutations of Antp (A–C), Dfd (D–F), and Ubx (G–I). (A) Wild-type antenna, with distal arista (ar) indicated by an arrowhead; (B) Antp^Ns–directed transformation of antenna toward leg with distal claw (cl, arrowhead); (C) the transformation is attenuated in Antp^Ns/Med19² trans-heterozygotes, as shown by the presence of a partial arista (ar, arrowhead). (D) Wild-type head, with the maxillary palp (Mx) indicated by arrowhead. (E) Dfd¹ provokes head defects including reduced eyes and the appearance of ectopic Mx (arrowhead), here positioned behind the antenna. (F) In Dfd¹/Med19² heterozygotes (or here, Dfd¹Med19²/+ Med19^P), no ectopic Mx were observed. (G) Wild-type wing. (H) Homozygote for the Ubx^Cbx1 gof allele that expressed Ubx protein in the posterior compartment of the wing. Note the discrete hemi-haltere induced by Ubx, which is oriented at right-angles relative to the longitudinal wing axis. (I) In Ubx^Cbx1 Med19²/Ubx^Cbx1 Med19^P wings, the posterior wing is no longer organized as a hemi-haltere, and the cellular trichomes are reoriented toward the long wing axis (arrow).