FB2026_02 , released June 18, 2026
Allele: Dmel\nclb1
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General Information
Symbol
Dmel\nclb1
Species
D. melanogaster
Name
FlyBase ID
FBal0263561
Feature type
allele
Associated gene
Associated Insertion(s)
Carried in Construct
Key Links
Allele class
Nature of the Allele
Allele class
Progenitor genotype
Cytology
Description

Imprecise excision of P{EPgy2}CG6751EY10712 results in an internal deletion within P{EPgy2}CG6751EY10712.

Mutations Mapped to the Genome
Curation Data
Type
Location
Additional Notes
References
Variant Molecular Consequences
Associated Sequence Data
DNA sequence
Protein sequence
 
Expression Data
Reporter Expression
Additional Information
Statement
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Marker for
Reflects expression of
Reporter construct used in assay
Human Disease Associations
Disease Ontology (DO) Annotations
Models Based on Experimental Evidence ( 0 )
Disease
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Modifiers Based on Experimental Evidence ( 0 )
Disease
Interaction
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Comments on Models/Modifiers Based on Experimental Evidence ( 0 )
 
Disease-implicated variant(s)
 
Phenotypic Data
Phenotypic Class
Phenotype Manifest In
Detailed Description
Statement
Reference

nclb1/nclb2 transheterozygotes are semi-viable, exhibit a significant delay in pupation, coupled with a significantly smaller body size/volume in both larvae and pupae, as compared to controls. nclb1 homozygotes also show a small larval body size, as compared to controls.

nclb1 mutant adult testes exhibit a reduced number of germ cells and an absence of mature sperm.

nclb1 homozygous and nclb1/nclb2 trans-heterozygous mutant testes do not exhibit multicellular cysts beyond four to eight cells. Fewer differentiating cysts are found, indicating that cysts degenerate after the four- to eight-cell stage. There isn't an increase in apoptosis (according to activated caspase levels) in these mutants. A few large germ cells are observed further from the hub, but these only contain round fusome material that does not extend between germ cells, indicating that any germ cells that do progress to this stage are no longer part of cysts and are developing abnormally. Somatic cysts do appear to be able to differentiate in these mutants.

nclb1 homozygous and nclb1/nclb2 trans-heterozygous mutant testes have fewer hub-proximal germ cells compared to wild-type, with a further reduction seen at days 5 and 10. These mutant germ cells still establish a male sexual identity and transition normally to become male germline stem cells. However, these germline stem cells are not properly maintained in the testis.

Ovaries from 5-day-old nclb1/nclb2 mutant adults contain ample germline and exhibit clear signs of egg chamber development; however, some germline loss is observed in 10-15 day old females. In newly eclosed females, a few mature eggs are observed, resulting in the limited fertility of these females. However, most of the egg chambers are arrested around stage 5 of development.

External Data
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Phenotypic Class
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Genetic Interactions
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Xenogenetic Interactions
Statement
Reference
Complementation and Rescue Data
Comments

Expression of nclbScer\UAS.P\T.cCa in the germline under the control of Scer\GAL4nos.UTR.T:Hsim\VP16 is sufficient to rescue the germline loss phenotype observed in nclb1/nclb2 mutants. Rescued testes have a wild-type appearance, with numerous germline stem cells associated with the hub and ample numbers of differentiating spermatogenic cysts. In addition, these rescued males have elongated spermatids and are completely fertile.

Expression of nclbScer\UAS.P\T.cCa under the control of Scer\GAL4αTub84B.PL rescues the germline and fertility defects found in nclb1/nclb2 mutants.

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Synonyms and Secondary IDs (2)
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    References (2)