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General Information
D. melanogaster
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Feature type
Associated gene
Associated Insertion(s)
Carried in Construct
Key Links
Allele class
Nature of the Allele
Allele class
Mutations Mapped to the Genome
Additional Notes
Associated Sequence Data
DNA sequence
Protein sequence
Progenitor genotype
Carried in construct
Nature of the lesion

UASt regulatory sequences drive expression of a fusion protein consisting of the ectodomain of fra fused to the transmembrane and cytoplasmic domains of robo1. The protein is tagged at the C-terminal end with 6 Tag:MYC tags.

Allele components
Product class / Tool use(s)
Encoded product / tool
Expression Data
Reporter Expression
Additional Information
Marker for
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Reporter construct used in assay
Human Disease Associations
Disease Ontology (DO) Annotations
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Disease-implicated variant(s)
Phenotypic Data
Phenotypic Class
Phenotype Manifest In
Detailed Description

Misexpression of fra::roboScer\UAS.FR.T:Hsap\MYC in the contralateral eagle (eg) neurons under the control of Scer\GAL4eg-Mz360 prevents the posterior subset of eg axons, but not the anterior, from crossing the midline.

Expression of fra::roboScer\UAS.FR.T:Hsap\MYC with Scer\GAL4Cha.7.4 leads to a severe depletion or absence of cholinergic axons in the commissures, efficiently displacing cholinergic axon terminals out of the dorsal motor neuropile. Under these conditions contact of motorneuron dendrites with cholinergic interneuron terminals is severely reduced and potentially absent at 18.5 hours after egg laying, unlike in the wild-type; yet the overall organisation of the neuropile, including the distribution of Fas2-positive tracts, is not affected. Dendritic intermediate (MN-LL1) and lateral (MN-DA3) territories also remain distinct, though they appear more variable compared to controls.

Expression of fra::roboScer\UAS.FR.T:Hsap\MYC driven by Scer\GAL4elav.PLu does not lead to a significant reduction in commissural axon thickness.

Expression of fra::roboScer\UAS.FR.T:Hsap\MYC when driven by Scer\GAL4unspecified, causes a loss of commissure phenotype.

Scer\GAL4elav.PLu driven expression in the nervous system generates animals with commissures that are significantly thinner than wild-type. These flies are viable and fertile and can be used to cross with each other generating embryos expressing higher levels of fra::roboScer\UAS.FR.T:Hsap\MYC. The progeny of these crosses show phenotypes ranging from wild-type to completely commissureless, the strength of which correlates strongly with the level of expression. In higher expressing lines, defects in motor neuron innervation are also seen. There is a dramatic reduction in innervation (78%, n=155) of muscles 7 and 6 by motorneuron RP3 (which is part of the intersegmental nerve b - ISNb). ISNb also displays other defects, predominantly bypass and stalls. In contrast to fra and Netrin mutants the ISN never crosses the segment border nor fasciculates with the ISN in the adjacent segment. The transverse nerve (TN) fails to form over muscles 7 and 6; both branches (the LBD and the TMN axons) stall and do not enter the region of the ventral muscles (75%, n=148).

External Data
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Phenotypic Class
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Additional Comments
Genetic Interactions

Pan-neuronal expression of fra::roboScer\UAS.FR.T:Hsap\MYC under the control of Scer\GAL4elav.PLu partially suppresses the midline crossing phenotype seen in robounspecified mutants. Many of the most medial ipsilateral axons still cross the midline.

Expression of fra::roboScer\UAS.FR.T:Hsap\MYC in the ap neurons under the control of Scer\GAL4ap-md544 partially rescues the midline crossing phenotype seen in robounspecified mutants. Some segments have ap axon tracts on both sides of the midline.

Co-expression of PakScer\UAS.T:Myr1 and fra::roboScer\UAS.FR.T:Hsap\MYC under the control of Scer\GAL4elav.PLu leads to a striking reduction in commissural axon thickness.

When two copies of P{UAS-fra-robo-Myc} expressed under the control of Scer\GAL4elav.PLu are combined with Df(1)NP5 (which removes both NetA and NetB), a suppression of the P{UAS-fra-robo-Myc} phenotype is seen. In combination with fraGA957 however, no suppression is seen. When both commScer\UAS.cKa and fra::roboScer\UAS.FR.T:Hsap\MYC are both expressed in all neurons by Scer\GAL4elav.PLu, suppression of the fra::roboScer\UAS.FR.T:Hsap\MYC phenotype is seen with some significant commissure formation in greater than 60% of segments (n+29 animals).

Xenogenetic Interactions
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Synonyms and Secondary IDs (3)
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    References (6)