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General Information
Symbol
Dmel\Nrx-IV4304
Species
D. melanogaster
Name
FlyBase ID
FBal0058467
Feature type
allele
Associated gene
Associated Insertion(s)
Carried in Construct
Also Known As
Nrx4304, nrxIV4304, Nrx IV4304
Key Links
Nature of the Allele
Mutations Mapped to the Genome
 
Type
Location
Additional Notes
References
Associated Sequence Data
DNA sequence
Protein sequence
 
 
Progenitor genotype
Cytology
Nature of the lesion
Statement
Reference
Expression Data
Reporter Expression
Additional Information
Statement
Reference
 
Marker for
Reflects expression of
Reporter construct used in assay
Human Disease Associations
Disease Ontology (DO) Annotations
Models Based on Experimental Evidence ( 0 )
Disease
Evidence
References
Modifiers Based on Experimental Evidence ( 0 )
Disease
Interaction
References
Comments on Models/Modifiers Based on Experimental Evidence ( 0 )
 
Disease-implicated variant(s)
 
Phenotypic Data
Phenotypic Class
Phenotype Manifest In
Detailed Description
Statement
Reference

Nrx-IV4304 mutant embryos display malformations of midline glia and of the ventral nerve cord axonal scaffold (revealed by immunolabelling with specific markers).

Embryos have a leaky blood-brain barrier.

Embryos show defects in blood-brain barrier function in the central nervous system in a dextran injection assay.

Mutant embryos lack a functional blood-brain barrier; 10kDa dextran injected into the hemolymph of stage 17 mutant embryos penetrates the central nervous system (CNS) within 15 minutes, whereas no penetration of the dye into the CNS is seen in wild-type embryos.

Homozygous stage 16-17 embryos lack a functional transepithelial barrier in the salivary glands (as analysed using a dye exclusion assay).

10, 70, and 500 kDa labeled dextran molecules can easily penetrate into the CNS in Nrx-IV4304 mutant embryos.

Stage 17 homozygous embryos show loss of the blood brain barrier (assayed by studying dextran uptake in living embryos).

In Nrx-IV4304 homozygotes lateral pentascolopidial chordotonal organs have a disorganised morphology and rounded, rather than fusiform scolopales. Unlike in wild-type embryos, lateral pentascolopidial chordotonal organs in these embryos fail to exclude a 10kDa dextran dye. Ultrastructural analyses of peripheral nerves in these mutants at late stages of embryogenesis show that, while glial membranes are present and normally spaced around these nerves, the associated septate junctions linking inner and outer glial sheath cells are missing and the boundary between the inner glial membrane and axolemma is abnormally fuzzy.

The tracheal systems of lates stage Nrx-IV4304 homozygous embryos have overgrown tubes with unusual expansions, defects in the accumulation of lumen antigens and lumen breaks.

Homozygous embryos have dorsal closure defects; dorsal holes are seen in the cuticle. Necrosis is seen in the salivary glands.

Transheterozygotes with Df(3L)vin8 or Df(3L)BK9 are lethal, rare adults escapers are occasionally obtained. Transheterozygous embryos with Df(3L)BK9 show a complete absence of muscle-propagation waves. Absence of Nrx-IV causes neuronal connectivity defects, affects the septate junctions between scolopale and cap cells resulting in abnormal morphology of scolopales (smooth septate junctions are unaffected, pleated septate junctions lose their characteristic ladder-like septae), 10% embryonic neuromuscular junctions fail to respond to nerve stimulation and the mean amplitude of evoked synaptic transmission of the remaining junctions is 40%-45% of wild type levels. Embryos exhibit a reduced ability to propogate action potentials.

External Data
Interactions
Show genetic interaction network for Enhancers & Suppressors
Phenotypic Class
Phenotype Manifest In
Additional Comments
Genetic Interactions
Statement
Reference
Xenogenetic Interactions
Statement
Reference
Complementation and Rescue Data
Not rescued by
Comments

Expression of Nrx-IVScer\UAS.T:Hsap\MYC under the control of Scer\GAL4arm.PS completely rescues the formation of septate junctions in Nrx-IV4304/Nrx-IV4304 embryos.

Expression of either Nrx-IVΔDL.Scer\UAS.T:Hsap\MYC or Nrx-IVΔLEL2.Scer\UAS.T:Hsap\MYC under the control of Scer\GAL4arm.PS partially rescues the formation of septate junctions in Nrx-IV4304/Nrx-IV4304 embryos.

Expression of either Nrx-IVΔLEL1.Scer\UAS.T:Hsap\MYC, Nrx-IVΔDL-LEL1.Scer\UAS.T:Hsap\MYC, Nrx-IVΔLEL1-LEL2.Scer\UAS.T:Hsap\MYC or Nrx-IVΔNT.Scer\UAS.T:Hsap\MYC under the control of Scer\GAL4arm.PS fails to rescue the formation of septate junctions in Nrx-IV4304/Nrx-IV4304 embryos.

Nrx-IV4304/Nrx-IV4304 embryos expressing Nrx-IVΔCT.Scer\UAS.T:Hsap\MYC under the control of Scer\GAL4arm.PS show the formation of septa throughout the length of epithelial membranes (in contrast to the restriction to the apicolateral areas which is seen in wild type).

Nrx-IV4304/Nrx-IV4304 embryos expressing Nrx-IVLEL1.Scer\UAS.T:Hsap\MYC under the control of Scer\GAL4arm.PS fail to form septate junctions, although occasional septae are seen.

Expression of Nrx-IVScer\UAS.T:Hsap\MYC under the control of Scer\GAL4Act5C.PU rescues the transepithelial barrier defect seen in the salivary glands of Nrx-IV4304/Nrx-IV4304 embryos.

The transepithelial barrier defect seen in the salivary glands of Nrx-IV4304/Nrx-IV4304 embryos is not rescued by expression of Nrx-IVΔDL.Scer\UAS.T:Hsap\MYC, Nrx-IVΔLEL1.Scer\UAS.T:Hsap\MYC, Nrx-IVΔLEL2.Scer\UAS.T:Hsap\MYC, Nrx-IVΔDL-LEL1.Scer\UAS.T:Hsap\MYC, Nrx-IVΔLEL1-LEL2.Scer\UAS.T:Hsap\MYC, Nrx-IVΔNT.Scer\UAS.T:Hsap\MYC, Nrx-IVΔCT.Scer\UAS.T:Hsap\MYC or Nrx-IVLEL1.Scer\UAS.T:Hsap\MYC under the control of Scer\GAL4Act5C.PU.

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Mutant
Wild-type
Stocks (2)
Notes on Origin
Discoverer
External Crossreferences and Linkouts ( 0 )
Synonyms and Secondary IDs (9)
References (23)