Breakpoint in Ubx.
Transformation of posterior portion of haltere toward wing, replacement of A1 tergite by post-notal tissue, no extra legs. A1 setal belt is intermediate between A1 and T3 type belts. Ventral pits on all abdominal segments.
Ubxbxd-100/Ubxbxd-111 larvae have dorsal histoblast cells in T3. The anterior dorsal histoblast nests are sometimes inverted in Ubxbxd-111/Ubx1 flies. The ventral histoblast nest of A1 is shifted to a more ventral position in Ubxbxd-111/Ubxbxd-100 flies.
Hemizygotes display ventral setal belt on the first abdominal segment is intermediate between the normal third thoracic belt and the normal first abdominal belts.
Lewis.
The phenotype of a number of combinations of Ubx mutations has been investigated to determine the role of the bxd regulatory region in the modulation of Ubx expression.