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General Information
D. melanogaster
FlyBase ID
Feature type
Associated gene
Associated Insertion(s)
Carried in Construct
Also Known As
Key Links
Allele class
Nature of the Allele
Allele class
Mutations Mapped to the Genome
Additional Notes
Nucleotide change:


Reported nucleotide change:


Amino acid change:

R45term | del-PA; R45term | del-PB; R45term | del-PC

Reported amino acid change:


Associated Sequence Data
DNA sequence
Protein sequence
Progenitor genotype
Nature of the lesion

Nucleotide substitution: A?T.

Amino acid replacement: R45term.

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

del2/del4 ovarioles contain less developing egg chambers than wild-type. Egg chambers are often smaller than normal and sometimes lack an oocyte. Localization of the oocyte to the posterior pole is also affected. The oocyte is mispositioned in approximately 8% of mutant egg chambers such that it occupies a central or anterior position instead of the normal posterior location. While most older egg chambers in young del2/del4 mutants contain normal numbers of germline cells, younger egg chambers often contain fewer than 16 cells. Of total egg chambers scored, approximately 36% have too few germline cells. Many of these are likely to have resulted from a defect in encapsulation as the missing complement of cells can be found in a neighbouring egg chamber. Oocytes in young females habour fewer than 4 ring canals, in approximately 3% of egg chambers, suggesting that a mitotic defect exists in addition to a defect in encapsulation. A small number of ovarioles in each ovary maintain germline stem cells and these sometimes also contain clusters of germline cells with branched fusomes. From BrdU experiments, the remaining germline stem cells and cystoblasts are found to be mitotically active.

del2/del4 mutants lay few eggs and the eggshells exhibit aberrations indicative of patterning defects along both the anterior-posterior and dorsal-ventral axes. In addition, the eggs are often small and collapsed due to an open chorion at the anterior end. There is variable ventralisation of eggshells indicated by a loss of dorsal appendage material. Most del2/del4 eggs exhibit ventralisation phenotypes ranging from a reduction to a total absence of appendages. Eggshell defects along the anterior-posterior axis are apparent as well. The aeropyle (a respiratory structure) is malformed in the vast majority of all del2/del4 eggs, exhibiting a intermediary morphology between aeropyle and micropyle.

del2/del4 mutants exhibit karyosome defects. The karyosome does not form properly in over 50% of del2/del4 mutant oocytes. DNA staining reveals threadline structures or blobs of staining. In less than 5% of oocytes, chromosomes exhibit polyploidy indicative of a partial loss of oocyte fate.

Approximately 54% of del2/del4 germaria in young females contain several germ cells undergoing apoptosis compared to approximately 2% of controls.

del2/del4 mutant germaria contain at most only one highly-branched fusome instead of 3-4, as observed in wild-type. Instead, large spectrosome-like and barbell-shaped structures accumulate in del2/del4 mutant germaria. These cells do not appear to represent stem cells dislodged from their niche, since their fusome-like structures are larger than stem cell spectrosomes.

del2/del4 mutants exhibit defects in microtubule formation. While most mitotic spindles and microtubule arrays appear normal at a gross level, some abnormalities are observed, such as accumulation of tubulin in early region 1 of germaria. Aberrations in mitotic spindles, most commonly totally collapsed spindles, but occasionally wavy spindles, are also observed.

While the general organisation of microtubule arrays appears normal in del2/del4, there is evidence of failure in focusing minus ends of the array.

del2/del4 males are sterile. Their germline cysts have reduced numbers of highly branched fusomes.

Normal number of egg chambers, produce eggs with fused dorsal appendages or without dorsal appendages.

homozygous females have normal numbers of developing egg chambers of all stages in their ovaries. The eggs produced by the females very frequently have fused dorsal appendages, or lack dorsal appendages altogether and remain unfertilized. female-sterile

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

Addition of Khc::nodT:Ecol\lacZ to del2/del4 mutants exacerbates the ovarian phenotype.

Expression of a single copy of αTub84BScer\UAS.P\T.T:Avic\GFP-S65C, in del2/del4 mutants, under the control of Scer\GAL4nos.UTR.T:Hsim\VP16 exacerbates the ovarian phenotype, such that young flies contain only rudimentary ovaries with few developing cysts exhibiting disorganisation of interior microtubules in cells in region 1 of del2/del4 mutant germaria as compared to heterozygotes.

Xenogenetic Interactions
Complementation and Rescue Data

One copy of delScer\UAS.T:Ivir\HA1, expressed under the control of Scer\GAL4nos.UTR.T:Hsim\VP16 restores egg chamber production in del2/del4 mutants, resulting on ovaries of wild-type size. Ovarioles in rescued females contain normal numbers of developing egg chambers that lack defects in encapsulation and oocyte positioning. karyosome formation is restored as well.

Expression of delScer\UAS.T:Ivir\HA1 in del2/del4 mutants, under the control of Scer\GAL4nos.UTR.T:Hsim\VP16 renders males fertile.

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Synonyms and Secondary IDs (4)
Reported As
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Name Synonyms
Secondary FlyBase IDs
    References (4)