Homeotic selector gene complexes Antennapedia
and Ultrabithorax
Left: The labial(lab)
and Deformed(Dfd) gene control the formation of head
segments. The Sex comb reduced (Scr) and Antennapedia(Antp) genes specify the identity of the first two thoracic
egments. The remaining gene in the complex, Proboscipedia(Pb),
may not act during embryogenesis, but may be required to maintain the differentiated
state in adult. In Antp
mutants, the labial palps are transformed into legs.
Right: The Ultrabithorax(Ubx)
gene controls structures in the posterior compartment of T2 (wings)
and structures in T3 (halteres). The two other genes, abdominalA(abdA) and AbdominalB(AbdB), specify
the segmental identifies of the eight abdominal segments (A1-A8). In
Ubx mutants, halteres are transformed into wings.
