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General Information
Symbol
Dmel\Sema2bf02042
Species
D. melanogaster
Name
FlyBase ID
FBal0161409
Feature type
allele
Associated gene
Associated Insertion(s)
Carried in Construct
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
Insertion components
PBac{WH}Sema2bf02042
Product class / Tool use(s)
Encoded product / tool
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

Sema-2bf02042 mutant third instar larvae display increased dendritic non-contacting crossing in the class I and IV dendritic arborizing (da) neurons. However, the overall morphology of axonal projections of class IV da neurons in the ventral nerve cord is normal as is the total number and morphology of epidermal cells.

Sema-2bf02042/Df(2R)Sema-2b-C4 mutant larvae display increased dendritic non-contacting crossing in the class IV da neurons, the severity of this phenotype was intermediate between that of Sema-2bf02042 and Df(2R)Sema-2b-C4 alone.

The proportion of enclosed (=not attached to the extracellular matrix, ECM) dendrites in the class IV da neurons is progressively increased in the Sema-2bf02042/Df(2R)Sema-2b-C4 larvae compared to wild-type from 72hr AEL onwards. This increase is mainly due to the loss of ECM attachment in terminal dendrites.

In Sema-2bf02042 homozygous pupae, 24 hours after puparium formation, the dorsolateral axon bundle is enlarged at the expense of the ventromedial bundle, shifting the average dorsolateral/ventromedial ratio to 4.77.

In Sema-2bf02042 brains, the majority of axons for both Or92a and Or67b ORN classes take dorsolateral trajectories around the antennal lobe and terminate in specific ectopic loci in the dorsolateral antennal lobe. Residual axons that take the ventromedial trajectory terminate in approximately correct target regions. Or67d and Or88a ORN classes, correctly target the DA1 and VA1d glomeruli, respectively, in Sema-2bf02042 brains.

The ventromedial trajectory of Or22a and Or47a-expressing axons is severely affected in Sema-2bf02042 homozygous mutant brains. However, their glomerular targeting appears normal.

Sema-2bf02042 Scer\FLP1hs.PG-based MARCM clones exhibit ectopic dorsolateral trajectories and severe mistargeting.

Sema-2bf02042 Scer\FLP1ey.PN reverse MARCM mutants exhibit significant targeting defects in multiple ventromedial ORN classes, consistent with the idea that Sema-2b from ORNs also acts as a ligand to mediate axon-axon interactions.

In Sema-2bf02042 paired AM29+ axon MARCM clones, both axons project dorsolaterally, implying that Sema-2b is essential for ventromedial axon pathway choice.

External Data
Interactions
Show genetic interaction network for Enhancers & Suppressors
Phenotypic Class
Phenotype Manifest In
Enhanced by
NOT Enhanced by
Suppressed by
Suppressor of
Statement
Reference
Other
Additional Comments
Genetic Interactions
Statement
Reference

The increased dendritic non-contacting crossing in the class IV dendritic arborizing (da) neurons seen in Sema-2bf02042 mutant larvae is not enhanced by the loss of Sema-2a : Sema-2bf02042,Sema-2a03474/Df(2R)A15 mutant larvae display the same amount of dendrite self-crossing as Sema-2bf02042 mutants alone.

Expression of trcScer\UAS.T:Zzzz\FLAG under the control of Scer\GAL4ppk.PU in the Sema-2bf02042/Df(2R)Sema-2b-C4 mutant larvae background exacerbated the increased dendritic crossing phenotype in the class IV da neurons displayed by the Sema-2bf02042/Df(2R)Sema-2b-C4 mutants.

Expression of trcS292A.T449A.Scer\UAS.T:Zzzz\FLAG under the control of Scer\GAL4ppk.PU in the Sema-2bf02042/Df(2R)Sema-2b-C4 mutant larvae background exacerbated the increased dendritic crossing phenotype in the class IV da neurons displayed by the Sema-2bf02042/Df(2R)Sema-2b-C4 mutants.

Expression of trcScer\UAS.T:Myr-Src64B under the control of Scer\GAL4ppk.PU in the Sema-2bf02042/Df(2R)Sema-2b-C4 mutant larvae background significantly suppressed the increased dendritic crossing phenotype in the class IV da neurons displayed by the Sema-2bf02042/Df(2R)Sema-2b-C4 mutants.

Simultaneous expression of mewScer\UAS.cMBa and mysScer\UAS.cDa under the control of Scer\GAL4ppk.PU in the Sema-2bf02042/Df(2R)Sema-2b-C4 mutant larvae background fully rescued the increased dendritic crossing phenotype in the class IV da neurons displayed by the Sema-2bf02042/Df(2R)Sema-2b-C4 mutants.

Sema-2a03474 Sema-2bf02042 double homozygous mutants exhibit ORN axon trajectory defects, with most axons projecting dorsolaterally. Expression of Sema-2b3'UTR.Scer\UAS in adult ORNs, under the control of Scer\GAL4peb-GAL4 and Scer\GAL80Orco, in these double mutants leads to Sema-2b-expressing ORNS exhibiting three kinds of trajectory. In 15% of cases, axons are split between the dorsolateral and ventromedial trajectories. In the remaining 85% of cases, however, all axons exclusively chose either the ventromedial or dorsolateral trajectory, with nearly equal probability.

In Sema-2bf02042, mamk1514 double mutant paired axon clones (generated through expression of Scer\FLP1hs.PG, Scer\GAL80ts.╬▒Tub84B and Scer\GAL4AM29), both neurons chose a dorsolateral axon trajectory, a phenotype opposite to that of mamk1514 paired clones. Sema-2b removal only partially reverts the mamk1514 phenotype in glomerular targeting, as double-mutant axons skip the DL4 glomerulus in 46% of clones despite taking the correct dorsolateral trajectory that passes by the target DL4 glomerulus.

Xenogenetic Interactions
Statement
Reference
Complementation and Rescue Data
Comments

The increased dendritic non-contacting crossing in the class IV da neurons seen in Sema-2bf02042/Df(2R)Sema-2b-C4 mutant larvae can be rescued by ectopic expression of Sema-2bScer\UAS.cUa or Sema-2bScer\UAS.T:Avic\GFP,T:Mmus\Cd8a under the Scer\GAL4A58 driver, whereas expression of Sema-2bScer\UAS.cUa under Scer\GAL4ppk.PU does not rescue the phenotype.

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Mutant
Wild-type
Stocks (1)
Notes on Origin
Discoverer
External Crossreferences and Linkouts ( 0 )
Synonyms and Secondary IDs (6)
Reported As
Symbol Synonym
CG33960f02042
CG4383f02042
Sema-2bf02042
Sema2bf02042
sema-2bf02042
Name Synonyms
Secondary FlyBase IDs
    References (4)