Polytene chromosomes normal.
adult muscle system & abdominal segment 1
ectoderm & metathoracic segment
Ubxbx-3/Df(3R)P2 flies show transformation of the anterior compartment of T3 (T3a) into the anterior compartment of T2 (T2a). The homeotically transformed T3 segment can contain DVM-I, DVM-III, DLM and DFM muscles. The homeotic DVM-I muscle is composed of one fibre and the diameter of the homeotic DVM-I fibre is less than that seen in T2. Homeotic DVM-II muscles are not seen. Ubxabx-1 Ubxbx-3 Ubx61d Ubxpbx-1/Df(3R)P2 mutants show transformation of T3 into T2 resulting in the replacement of halteres with a second set of wings. The homeotically transformed T3 segment resembles T2 in size. The homeotically transformed T3 segment can contain homeotic DVM-I, DVM-II, DVM-III, DLM and DFM muscles.
In Ubxabx-1 Ubxpbx-1 Ubxbx-3 triple mutant flies the T3 ectoderm transforms toward T2 identity. Transformation changes the pattern of myoblasts on the transformed haltere disc and their pattern of migration, but indirect flight muscles do not form as there are no larval templates. The haltere disc is almost completely transformed into a wing disc. Adults have two pairs of wings, but the homeotically transformed T3 has only rudimentary indirect flight muscles.
Does not affect the frequency of the trx bithorax-variegated phenotype in heterozygous combination with Df(3R)red-P52.
Homozygotes and transheterozygotes of Ubx alleles demonstrate a significant enhancement of the bx phenotype when in combination with E(bx)2. Haltere to winglike and metanotum to mesonotumlike transformations are enhanced.
Different genetic combinations of Pc alleles and Ubx alleles suggest that the products of the bx region of Ubx are responsible for the "cbx" phenotype of the Pc mutations and in the absence of Pc the overexpression of bx gene products suppresses the pbx insufficiency phenotype in the posterior segments.
Haltere are transformed to wing and are 20-25% of wing size, dorsal tissue of T3 is incompletely transformed to metanotum, hypopleural plates are incompletely transformed to sternopleural plates, 8-10 hypopleural bristles are still present and the anterior third leg displays a strong transformation to anterior second leg, as seen by the bristle pattern. Phenotype can be suppressed by su(Hw) mutations.
Ubxbx-3 shows the "ppx" transformation at 17oC: ventral regions of T2p and T3p are affected.
Flies have normal transversal fascicles in the adult CNS.
Ubxbx-3 Ubxbxd-106/Df(3R)P115 clones in T3 show a transformation to T2 in legs and halteres. Clones in the posterior compartments of legs in T2 or T3 do not show transformation into prothorax.
Strong transformation of anterior third thoracic segment to second thoracic segment.
Homozygotes show a variable transformation of anterior haltere to wing. The transformed appendage is often misshapen, the most proximal sensilla fields are the most perfectly transformed, whereas the more distal fields often remain haltere-like. Dorsally on the transformed appendage, the ANWP and Teg. sensilla always appear normal, field d.Rad.A occasionally shows extra type-2 sensilla, the d.Rad.B and d.Rad.C fields often have fewer sensilla than normal, and the most distal sensilla have rudimentary sockets rather than smooth depressions. Sensilla on the medial radius are abnormal; d.Rad.D consists of aberrant type-5 sensilla not representative of wing or haltere, the d.Rad.E sensilla appear wing-like but crowded, and the dHCV and GSR sensilla of the distal radius are surrounded by extra sensilla of varying numbers and morphology. Ventrally, the v.Rad.A sensilla show normal morphology, although a fifth sensillum is often seen, the v.Rad.B sensilla are usually normal although they may be absent and the v.Rad.C field is sometimes replaced by fused, pedicellar-type sensilla which extend out over the more distal regions of the ventral radius. Ubxbx-3 Ubxpbx-1 flies show a transformation of haltere to wing. The transformed appendage is smaller than wild-type, the cuticle is often folded, and the veins are often obscure. The phenotype of the sensilla is similar to Ubxbx-3 homozygotes, except that the homeotic transformation in the proximal radius region is more complete, and d.Rad.D contains sensilla resembling, but not identical to, the pedicellar sensilla of the haltere. Ubxabx-1 Ubxbx-3 Ubxpbx-1 flies have a transformation of haltere to wing. The homeotic appendage is somewhat smaller than a normal wing, but usually has the full wild-type complement of wing sensilla, with each type located in the normal position and having normal morphology. The only exception is an occasional decrease in the number of sensilla in fields d.Rad.B and d.Rad.C, and rarely, one or a few extra haltere pedicellar bristles.
Hemizygous Ubxbx-3/Df(3R)P115 tissue shows a transformation of the metathoracic segment (both dorsal and ventral discs) to the mesothoracic segment in gynandromorphs. This transformation is restricted to the anterior compartment.
The frequency of variegated bithorax transformations seen in Df(3R)red-P52 heterozygotes is not increased in flies also heterozygous for Ubxbx-3.
Heterozygotes with Ubx61d has halteres partially wing-like but lack conversion of metanotum towards mesonotum.
Ubxbx-3 has viable phenotype, suppressible by xen[+]/Asxxen-72-3
Ubxbx-3/Ubxbxd-51j, ssa has visible phenotype
Ubx130/Ubxbx-3 has haltere disc anterior compartment phenotype, suppressible | partially by Scer\GAL4ptc-559.1/tkvUAS.cLa
Ubxbx-3/Ubx6.28 has haltere disc anterior compartment phenotype, suppressible | partially by Scer\GAL4ptc-559.1/tkvUAS.cLa
Ubxbx-3 has phenotype, suppressible by su(Hw)unspecified
Ubxbx-3/Ubxbxd-51j, ssa has leg phenotype
Heterozygosity for Asxxen-72-3 in a homozygous Ubxbx-3 mutant background causes lethality at the third instar larval stage.
The increased size of the anterior compartment that is seen in the haltere discs of Ubx6.28/Ubxbx-3 animals is partially suppressed by expression of tkvScer\UAS.cLa under the control of Scer\GAL4ptc-559.1.
Expression of abd-A1dB5.Scer\UAS results in an almost complete rescue of the transformed haltere phenotype of Ubxabx-1 Ubxbx-3 Ubxpbx-1/UbxLDN flies. The P{GawB}UbxLDN insertion within the UbxLDN flies drives expresssion of abd-A1dB5.Scer\UAS.
ssa Ubxbx-3 Ubxbxd-51j hemizygotes do not emerge as imagos. Dissection of late pupae reveals flies have four pairs of legs (Ubxbx-3 Ubxbxd-51j phenotype) and the fourth pair of legs exhibit severe disruption of segmentation and an improvement in the segmentation of the third pair.
The partial transformation of haltere into wing which is seen in UbxLDN/Ubxabx-1 Ubxbx-3 Ubxpbx-1 flies is strongly suppressed by expression of either UbxScer\UAS.cCa or UbxIIa.Scer\UAS.cRa under the control of Scer\GAL4Ubx-LDN.
The partial transformation of haltere into wing which is seen in UbxLDN/Ubxabx-1 Ubxbx-3 Ubxpbx-1 flies is partially suppressed by expression of one copy of UbxIVa.Scer\UAS.cRa under the control of Scer\GAL4Ubx-LDN and is almost completely suppressed by expression of two copies of UbxIVa.Scer\UAS.cRa under the control of Scer\GAL4Ubx-LDN.
Stern.
Stern, 2 Feb. 1925.
The original Ubxbx-3 chromosome had two insertions in Ubx, a gypsy insertion at -57kb and a Doc insertion at -53kb. Only the gypsy element is responsible for the Ubxbx-3 mutant phenotype: a recombinant chromosome without the Doc insertion has the same phenotype as the original chromosome, and loss of the gypsy insertion results in reversion of the Ubxbx-3 mutant phenotype.
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.