A gene residing at 58.8 on the genetic map and within segment 89E of the salivary map of Drosophila melanogaster. The bx gene is one of a cluster of three genes that specify the type of differentiation that cells in the segments starting at the posterior portion of the second thoracic segment through the eighth abdominal segment will undergo. The homeotic mutations illustration shows a bx mutant with four wings. Therefore the normal function of this gene is to specify that the hind pair of imaginal discs (q.v.) form halteres (q.v.) not wings during metamorphosis. The three genes of the bithorax complex encode DNA-binding proteins with homeodomains. See Chronology, 1978, Lewis; 1983, Bender et al.; floral organ identity mutations, homeotic mutations, Hox genes, metamerism, Polycomb, proboscipedia, segment identity genes, spineless-aristapedia.
Subjects: Genetics and Genomics.