Open Close
General Information
Symbol
Dmel\chb2
Species
D. melanogaster
Name
FlyBase ID
FBal0104957
Feature type
allele
Associated gene
Associated Insertion(s)
Carried in Construct
Also Known As
orbit2
Key Links
Nature of the Allele
Mutations Mapped to the Genome
 
Type
Location
Additional Notes
References
Associated Sequence Data
DNA sequence
Protein sequence
 
 
Cytology
Nature of the lesion
Statement
Reference

Imprecise excision of the P{lacW} element, resulting in a deletion extending from within the asparagine-synthetase gene to within the P{lacW} element.

Caused by aberration
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

Cultured primary neurons derived from either homozygous chb2 or chb2/Df(3L)BSC553 embryos have a significantly reduced axon length compared to wild-type controls.

chb2 mutant hemocytes exhibit a delay in migration along the ventral midline. Individual hemocytes fail to distribute evenly at stage 15, indicating a defect in contact repulsion. chb2 hemocytes are frequently seen in contact with one another for more than 15 minutes (wild-type hemocytes are rarely seen in contact for more than 10 minutes). chb2 hemocytes are still capable of migration to both epithelial wounds and in response to developmental guidance cues. chb2 mutant hemocytes migrating to wounds exhibit reduced directional persistence and an increase in migration speed when compared to wild-type cells.

Microtubules in chb2 mutant cells are highly dynamic and are able to both polymerize and undergo catastrophe. However, unlike in wild-type cells, microtubule polymerization is unpolarized: no microtubules are stabilized or bundled, with no microtubule arm developing.

Homozygous and chb2/chb4 embryos show ectopic crossing of the midline by axons in the central nervous system. Sema-2b-expressing neurons show erratic trajectories both approaching the midline and along the longitudinal neuropil in the central nervous system of homozygous embryos. The Sema-2b-positive axon tracts show a significant inward shift in their lateral position.

Mitotic defects are seen in the cells of the larval central nervous system in chb2/chbS068607 flies. Polyploid metaphase figures (16%), diploid metaphase figures with hypercondensed chromosomes (40%) and circular metaphase figures (3%) are seen. The metaphase to anaphase ratio and the mitotic index is increased compared to wild type. Third instar chb2/Df(3L)Pc-9a, chb3/chb2 or chb4/chb2 larvae lack imaginal discs and have a small central nervous system. More than 80% of total metaphase figures are polyploid, and more than 30% of polyploid figures have greater than an 8N chromosome complement. Circular metaphase figures and anaphase figures cannot be detected.

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

chb2 has axon phenotype, non-suppressible by CLIP-190KO/CLIP-190KO

Additional Comments
Genetic Interactions
Statement
Reference

The reduction in axon length seen in cultured primary neurons derived from homozygous chb2 embryos is unchanged if the embryos are also homozygous for CLIP-190KO.

Xenogenetic Interactions
Statement
Reference
Complementation and Rescue Data
Comments

Expression of chbScer\UAS.T:Avic\GFP in hemocytes under the control of Scer\GAL4srp.Hemo rescues microtubule arm formation in chb2 mutants. In addition, expression of chbScer\UAS.T:Avic\GFP restores contact repulsion between hemocytes resulting in wild-type levels of contact time between cells.

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
Name Synonyms
Secondary FlyBase IDs
    References (4)