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General Information
D. melanogaster
FlyBase ID
Feature type
Associated gene
Associated Insertion(s)
Carried in Construct
Also Known As
2Bc2, l(1)t76
Key Links
Nature of the Allele
Mutations Mapped to the Genome
Additional Notes
Associated Sequence Data
DNA sequence
Protein sequence
Progenitor genotype
Nature of the lesion
Expression Data
Reporter Expression
Additional Information
Marker for
Reflects expression of
Reporter construct used in assay
Human Disease Associations
Disease Ontology (DO) Annotations
Models Based on Experimental Evidence ( 0 )
Modifiers Based on Experimental Evidence ( 0 )
Comments on Models/Modifiers Based on Experimental Evidence ( 0 )
Disease-implicated variant(s)
Phenotypic Data
Phenotypic Class
Phenotype Manifest In
Detailed Description

br2Bc-2/Y males raised at 25oC show malrotated genitalia at full penetrance. Only 1% of br2Bc-2/Dp(1;Y)y267g19.1 males raised at 22-23oC show this phenotype.

At the onset of pupation, as staged by head eversion, br2Bc-2 hemizygotes exhibit the following phenotypes: 1. Mutant animals always possess some remnants of the larval proventriculus and gastric caeca, but in some cases they possess larval midgut structures, including a larval esophagus, proventriculus, and gastric caeca. While larval midgut destruction does not occur properly in br2Bc-2 hemizygotes, the adult epithelium is formed and the midgut appears to be arrested at a stage that is similar to the midgut of wild-type prepupae 2-4 h following puparium formation. 2. DNA fragmentation is detected in all larval midgut cells of br2Bc-2 hemizygotes at the onset of pupation, as staged by head eversion. 3. Mutant midgut cells contain intact mitochondria and do not exhibit obvious alterations in cytosolic structures from midguts of third instar larvae other than containing large spaces. Between the white prepua stage and head eversion, br2Bc-2 hemizygous mutant midguts decrease in length by an average of 65% in length compared to 85% in the wild-type.

Hemizygous males show neuropil fusion between the medulla and lobula, and between the lobula and lobula plate. The contour and thickness of the medulla, especially laterally, is irregular.

Homozygotes arrest development in late prepupae or in early pupae just after head eversion.

Mutant males form a puparium that appears normal but has an orange cast. Development arrests shortly after pupation.

Lethality acts at the late prepupal or early pupal stage.

Failure of salivary gland degeneration. Reduction in dorso-ventral class of indirect flight muscles. Proventriculus abnormality: foregut-midgut junction less proventriculus-like in appearance. Malpighian tubules and yellow body failed to develop, pupae and pharate adults contain multiple convoluted tubules.

There is no significant interaction between zip and br2Bc-2.

38% penetrance of abnormal SEG-TG separation phenotype, 34% of individuals have an abnormal optic lobe position and 64% with brain fusion failure. A few individuals also showed failure of head eversion and overt holes in the cuticle.

Puparium formation delayed by 12 hours. Puparia do not have a barrel-like shape.

Puparium formation delayed 12 hr.

External Data
Show genetic interaction network for Enhancers & Suppressors
Phenotypic Class
Phenotype Manifest In
Additional Comments
Genetic Interactions

Double heterozygotes with Eip74EFneo24 or Eip74EFDL-1 show no effect on development. More than 25% of Eip74EFneo24 carrying a single effective dose of br+ formed a misshapen puparium. This phenotype is 100% penetrant in a br2Bc-2 mutant background. Most double mutants die during the prepupal stage, earlier than either br2Bc-2 or Eip74EFneo24 mutants alone. In 16% of double mutants eye development proceeds to the point where pigment can be observed, but other discs do not undergo morphogenesis. In double mutants with Eip74EFDL-1 the lethal phase shifts earlier to the prepupal stage, and the puparium is extremely curved.

Xenogenetic Interactions
Complementation and Rescue Data
Fails to complement
Rescued by
Partially rescued by

br2Bc-2 is partially rescued by brBRcore.Z4.hs

br2Bc-2 is partially rescued by brZ2.hs


Expression of the brBRcore.NS.Z3.hs transgene partially rescues the malrotated genitalia phenotype of br2Bc-2 males; this is inversely related to temperature, with 40% of flies showing the phenotype at 22-23oC and only 14% showing the phenotype at 25oC.

br2Bc-2 animals are rescued by expression of brBRcore.NS.Z3.hs during larval development. Rescued flies that eclose have wild-type legs and wings and live for several days as fertile adults. br2Bc-2 animals are partially rescued by expression of brZ2.hs during larval development. Rescued flies that eclose have malformed wings and legs and die very soon after eclosing. br2Bc-2 animals are not rescued by expression of brBRcore.Q1.Z1.hs or brBRcore.TNT.Q1.Z1.hs during larval development. brBRcore.Z4.hs has a small effect on br2Bc-2 when expressed using 37oC heat shocks during larval development; some animals develop into late pupal stages, and very rarely, very malformed animals eclose.

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Notes on Origin
External Crossreferences and Linkouts ( 0 )
Synonyms and Secondary IDs (7)
References (27)