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General Information
Symbol
Dmel\stjDD106
Species
D. melanogaster
Name
FlyBase ID
FBal0221276
Feature type
allele
Associated gene
Associated Insertion(s)
Carried in Construct
Allele class
Mutagen
    Nature of the Allele
    Allele class
    Mutagen
    Mutations Mapped to the Genome
     
    Type
    Location
    Additional Notes
    References
    point mutation
    Nucleotide change:

    C13808172T

    Amino acid change:

    R193term | stj-PB; R193term | stj-PC; R193term | stj-PD

    Reported amino acid change:

    R192term

    Comment:

    Site of nucleotide substitution in mutant inferred by FlyBase based on reported amino acid change.

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

    Amino acid replacement: R192term.

    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 )
     
    Phenotypic Data
    Phenotypic Class
    Phenotype Manifest In
    Detailed Description
    Statement
    Reference

    stjDD106 and stjDD106/Df(2R)Exel7128 mutants die as late embryos. They do not exhibit any gross morphological abnormalities, but fail to hatch from their egg cases. In contrast with the wild-type 'beads on a string' morphology, neuromuscular junctions in 21h old stjDD106 (and stjDD106/Df(2R)Exel7128) embryos completely lack boutons, with only thin neurites extending onto the muscle surface throughout the body-wall musculature.

    In stjDD106 mutant embryos, motor neurons successfully navigate to and fix on their target muscles at the appropriate time. They exhibit normally shaped and sized growth cones. As early as 16 hours after egg laying, however, during the prevaricosity stage, neuromuscular junctions become abnormal, with thinner neurites and atypical branching. Although muscles 6, 7, 12 and 13 are each contacted by the neurons, the nerve often does not end by bifurcating into a T shape at the boundary between muscles 12 and 13, but instead bifurcates more ventrally, on muscle 6, in a Y shape that extends to the other muscles. Other aspects of embryonic development continue normally (for example, gut folding, ventral nerve cord retraction and trachea air-filling), but neuromuscular junction development never progresses past the prevaricosity stage and no boutons ever arise.

    In electron micrographs of stjDD106 mutant neuromuscular junctions exhibit long, thin processes containing active zones are found in place of the large round profiles of boutons. Neuronal processes average only 0.6υm across, compared to 3 υm in wild-type. Profiles wider than 1.3υm are never encountered. Despite these morphological changes, the active zones in stjDD106 mutant synapses look normal, having closely apposed pre- and post-synaptic densities of similar sizes, clusters of synaptic vesicles and T bars.

    Homozygous stjDD106 and transheterozygous stjDD106/Df(2R)Exel7128 mutants exhibit spontaneous miniature excitatory junction currents of wild-type amplitude, indicating that functional release sites are properly aligned with functional receptors, despite the absence of boutons. The frequency of these mEJPs is diminished by 64%, suggesting that fewer release sites are present and consistent with the 70% reduction in active zone area in the mutants, and the 61% decrease in the area of nerve-muscle contacts.

    Stimulation of motor axons in stjDD106 mutants does not evoke a postsynaptic response. The probability of release is reduced at least 1000-fold in the mutant compared to wild-type.

    stjDD106/stjDD106, stjDD106/Df(2R)CX1 or stjDD106/Df(2R)Exel7128 animals die as well-formed, late stage embryos.

    Adults with eyes that are homozygous for stjDD106 (due to somatic clones induced using Scer\FLP1Scer\UAS.cDa; Scer\GAL4ey.PH) have severely abnormal electro-retinograms (ERGs) in response to light: on/off transients are lacking and the sustained components of the response are abnormally slow in their onset and recovery.

    stjk10814/stjDD106 animals have an increase in branch number per-neuromuscular junction and a small (15%) but significant (p <0.05) increase in the mean number of boutons per neuro-muscular junction in third instar larvae despite decreased muscle size in these animals compared to controls. Normalized to muscle size, this corresponds to a 50% increase in bouton density.

    External Data
    Interactions
    Show genetic interaction network for Enhancers & Suppressors
    Phenotypic Class
    NOT Enhanced by
    Statement
    Reference
    NOT suppressed by
    Statement
    Reference
    Phenotype Manifest In
    NOT Enhanced by
    Statement
    Reference

    stjDD106 has motor neuron phenotype, non-enhanceable by cac20-3

    stjDD106 has bouton phenotype, non-enhanceable by cac20-3

    stjDD106 has synapse phenotype, non-enhanceable by cac20-3

    NOT suppressed by
    Statement
    Reference

    stjDD106 has motor neuron phenotype, non-suppressible by cac20-3

    stjDD106 has bouton phenotype, non-suppressible by cac20-3

    stjDD106 has synapse phenotype, non-suppressible by cac20-3

    Additional Comments
    Genetic Interactions
    Statement
    Reference

    cac20-3; stjDD106 double mutants are indistinguishable from stjDD106 single mutants.

    Xenogenetic Interactions
    Statement
    Reference
    Complementation and Rescue Data
    Partially rescued by
    Comments

    Expression of stjScer\UAS.Int.T:Ivir\HA1 under the control of Scer\GAL4elav-C155 rescues bouton formation in stjDD106 mutants.

    stjScer\UAS.T:Ivir\HA1; Scer\GAL4elav.PLu rescues the reduction of muscle size seen in stjDD106/stjk10814 third instar larvae and the increase in branch number per neuro-muscular junction but does not affect the increase in bouton number seen at neuromuscular junctions in these animals.

    Lethality due to stjDD106/stjDD196 is rescued by stjScer\UAS.T:Ivir\HA1 with Scer\GAL4da.G32, Scer\GAL4elav.PLu or both.

    Images (0)
    Mutant
    Wild-type
    Stocks (0)
    Notes on Origin
    Discoverer
    External Crossreferences and Linkouts ( 0 )
    Synonyms and Secondary IDs (3)
    Reported As
    Symbol Synonym
    2δ-3DD106
    stjDD106
    Name Synonyms
    Secondary FlyBase IDs
      References (2)