Lindsley & Grell, 1972, p. 257
discoverer: Hollander, 1934.
synonym: bxD; bithorax-Dominant; bxdD: bithoraxoid-Dominant, Bxl: Bithoraxlike.
references: 1937, DIS 8: 9, 77. Lewis, 1949, Heredity 3: 130. 1951, Cold Spring Harbor Symp. Quant. Biol. 16: 159-74 (fig.). 1954 Am. Naturalist 88: 225-39. 1955, Am. Naturalist 89: 73-89. 1963, Am. Zoologist 3: 33-56.
phenotype: Halteres of heterozygote about twice normal volume, characteristically with one or more hairs on anterior surface of swollen apical segment, or capitellum, of the haltere. No overlap with wild type and little variability; accurate scoring takes practice. Homozygous larva has, in addition to normally present mesothoracic pair of spiracles, both a metathoracic and a first abdominal spiracle pair. Flies homozygous for Ubx but carrying Dp(3;3)bxd100 = Dp(3;3)66C;89B5-6;89E2-3, which carries a normal allele of bx but none of bxd, have extreme bxd phenotype. Ubx/bx34e has oval, flat halteres; phenotype more extreme if the third chromosomes are heterozygous for a chromosome aberration with a breakpoint between the centromere and the bx locus; E. B. Lewis (1954) termed this the transvection effect. bx34eUbx/++ indistinguishabie from Ubx/+. Ubx/bxd has large, fleshy halteres like bxd/bxd; larva lacks first abdominal ventral row of setae. The cis types, Ubx bxd/++ and Ubx pbx/++, also indistinguishable from Ubx/+. Ubx/pbx has large halteres and causes transformation of posterior metathorax toward posterior mesotharax. Homozygous lethal. Enhances expression of PC and Scx (Hannah-Atava, 1964, Z. Vererbungslehre 95: 1-9). RK2.
cytology: Placed close to, if not in, doublet 89E1-2 (E. B. Lewis). Salivary chromosomes normal.
other information: Middle member of bx pseudoallelic series including, from left to right, bx, Cbx, Ubx, bxd, and pbx.
color figure : P. A Otto (original)
photograph : P. A. Otto (original; slide prepared by CBSC)
Both illustrations show a four-winged fly, obtained by combining the regulatory mutations bithorax and postbithorax of the Ubx gene.