FlyBase Allele Report: Dmel\Top2[suo3]

General Information

Symbol

Dmel\Top2^suo3

Species

D. melanogaster

Name

FlyBase ID

FBal0320788

Feature type

allele

Associated gene

Dmel\Top2

Associated Insertion(s)

Carried in Construct

Key Links

Genomic Maps

JBrowse

Allele class

Mutagen

ethyl methanesulfonate

Nature of the Allele

Allele class

Mutagen

ethyl methanesulfonate

(Mengoli et al., 2014)

Progenitor genotype

Cytology

Description

G to A transition in the 5' splicing site of the Top2 second intron (mutation is at nucleotide 1040 of the Top2 coding sequence). This is predicted to result in a premature stop codon.

(Mengoli et al., 2014)

Mutations Mapped to the Genome

Curation Data

Type

Location

Additional Notes

References

point_mutation

2L:19,451,246..19,451,246 [-]

Nucleotide change:

G19451246A

Reported nucleotide change:

G1040A

Comment:

G to A mutation in the splice donor of the second intron of Top2 leads to a stop codon at that site and early translation termination.

(Mengoli et al., 2014)

Variant Molecular Consequences

Associated Sequence Data

DDBJ / EMBL / GenBank

DNA sequence

Protein sequence

UniProtKB/Swiss-Prot

UniProtKB/TrEMBL

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

abnormal meiotic cell cycle | male (with Df(2L)Exel9043)

(Mengoli et al., 2014)

abnormal mitotic cell cycle | third instar larval stage (with Df(2L)Exel9043)

(Mengoli et al., 2014)

abnormal neuroanatomy | larval stage (with Df(2L)Exel9043)

(Mengoli et al., 2014)

lethal - all die during larval stage (with Df(2L)Exel9043)

(Mengoli et al., 2014)

Phenotype Manifest In

chromatin | male (with Top2^suo1)

(Mengoli et al., 2014)

chromosome | male (with Top2^suo1)

(Mengoli et al., 2014)

chromosome | third instar larval stage (with Df(2L)Exel9043)

(Mengoli et al., 2014)

chromosome | third instar larval stage (with Top2^suo1)

(Mengoli et al., 2014)

embryonic/larval salivary gland | larval stage | male (with Df(2L)Exel9043)

(Mengoli et al., 2014)

embryonic/larval salivary gland | larval stage | male (with Top2^suo1)

(Mengoli et al., 2014)

imaginal disc | larval stage (with Df(2L)Exel9043)

(Mengoli et al., 2014)

larval brain | larval stage (with Df(2L)Exel9043)

(Mengoli et al., 2014)

larval brain | third instar larval stage (with Df(2L)Exel9043)

(Mengoli et al., 2014)

larval brain | third instar larval stage (with Top2^suo1)

(Mengoli et al., 2014)

male germline cell (with Df(2L)Exel9043)

(Mengoli et al., 2014)

polytene chromosome | larval stage | male (with Df(2L)Exel9043)

(Mengoli et al., 2014)

polytene chromosome | larval stage | male (with Top2^suo1)

(Mengoli et al., 2014)

primary spermatocyte | male (with Top2^suo1)

(Mengoli et al., 2014)

secondary spermatocyte | male (with Top2^suo1)

(Mengoli et al., 2014)

Detailed Description

Statement

Reference

Top2^suo3/Df(2L)Exel9043 mutants survive until early third instar larva stage. The larvae are devoid of imaginal discs and have small brains compared to age-matched controls.

No meiotic divisions are observed in testes Top2^suo3/Df(2L)Exel9043 mutant males as the germline proliferation is severely impaired.

Top2^suo1/Top2^suo3 males show highly defective meiotic chromosome morphology and aberrant segregation with chromatin bridges and lagging chromosomal fragments in primary spermatocytes during meiosis I, resulting in secondary spermatocytes dividing without any chromosomes or if they've received some they display severe segregation defects.

The brains of Top2^suo3/Top2^suo1 transheterozygote third instar larvae (treated with colchicine and hypotonic solution) progress almost normally through mitosis although they show highly increased frequency of chromosomal aberrations including chromatin bridges and lagging chromosomal fragments compared to wild-type. In males as well as XXY females these aberrations are mostly isochromatid breaks preferentially involving the entirely heterochromatic Y chromosome and the third chromosome heterochromatin. In majority of metaphases with a broken Y chromosome the acentric fragment is either missing or present as an additional element. In XX females most of the aberrations are isochromatid breaks in 3L heterochromatin. The chromatin bridges are likely to involve sister rather than non-sister chromatids.

Top2^suo3/Df(2L)Exel9043 third instar larval brains display a dramatic drop in their mitotic index compared to wild-type controls. Metaphase figures are only rarely observed in the brain cells and when present their chromosomes appear as chromatin masses without recognizable individual chromosomes or chromatids. Their mitotic spindle however appears normal.

Top2^suo3/Top2^suo1 as well as Top2^suo3/Df(2L)Exel9043 males display defects in the morphology of the polytene chromosome X in larval salivary glands. The X chromosome appears bloated and is often detached from the chromocenter. Females display normal polytene chromosome morphology.

(Mengoli et al., 2014)

External Data

Linkouts

Interactions

Show genetic interaction network for Enhancers & Suppressors

Phenotypic Class

NOT suppressed by

Statement

Reference

Top2^suo3/Df(2L)Exel9043 has abnormal neuroanatomy | larval stage phenotype, non-suppressible by mei-41^29D

(Mengoli et al., 2014)

Top2^suo3/Df(2L)Exel9043 has abnormal neuroanatomy | larval stage phenotype, non-suppressible by tefu^atm-3/tefu^atm-3

(Mengoli et al., 2014)

Phenotype Manifest In

Enhanced by

Statement

Reference

Top2^suo1/Top2^suo3 has chromosome | third instar larval stage | male phenotype, enhanceable by mei-41^29D

(Mengoli et al., 2014)

Top2^suo1/Top2^suo3 has larval brain | third instar larval stage | male phenotype, enhanceable by tefu^atm-3/tefu^atm-3

(Mengoli et al., 2014)

Suppressed by

Statement

Reference

Top2^suo1/Top2^suo3 has embryonic/larval salivary gland | male | larval stage phenotype, suppressible by mof¹

(Mengoli et al., 2014)

Top2^suo1/Top2^suo3 has polytene chromosome | male | larval stage phenotype, suppressible by mof¹

(Mengoli et al., 2014)

NOT suppressed by

Statement

Reference

Top2^suo3/Df(2L)Exel9043 has larval brain | third instar larval stage phenotype, non-suppressible by mei-41^29D

(Mengoli et al., 2014)

Top2^suo3/Df(2L)Exel9043 has larval brain | third instar larval stage phenotype, non-suppressible by tefu^atm-3/tefu^atm-3

(Mengoli et al., 2014)

Enhancer of

Statement

Reference

Top2^suo1/Top2^suo3 is an enhancer of chromosome | third instar larval stage | male phenotype of mei-41^29D

(Mengoli et al., 2014)

Top2^suo1/Top2^suo3 is an enhancer of larval brain | third instar larval stage | male phenotype of mei-41^29D

(Mengoli et al., 2014)

Top2^suo1/Top2^suo3 is an enhancer of chromosome | third instar larval stage | male phenotype of tefu^atm-3

(Mengoli et al., 2014)

Top2^suo1/Top2^suo3 is an enhancer of larval brain | third instar larval stage | male phenotype of tefu^atm-3

(Mengoli et al., 2014)

Additional Comments

Genetic Interactions

Statement

Reference

The low mitotic index observed in Top2^suo3/Df(2L)Exel9043 third instar larval brains cannot be rescued by combination with either mei-41^29D or tefu^atm-3/tefu^atm-3.

The X polytene chromosome condensation defects observed in larval salivary glands of Top2^suo3/Top2^suo1 males can be rescued by combination with mof¹ in hemizygote state: the X polytene chromosome of mof¹/Y;Top2^suo3/Top2^suo1 double mutants shows normal condensation as well as banding pattern.

The increased frequency of chromosomal aberrations in third instar larval brain cells characteristic for Top2^suo3/Top2^suo1, mei-41^29D/Y or tefu^atm-3/tefu^atm-3 single mutant males is enhanced further in mei-41^29D/Y;Top2^suo3/Top2^suo1 or Top2^suo3/Top2^suo1;tefu^atm-3/tefu^atm-3 double mutants.

(Mengoli et al., 2014)

Xenogenetic Interactions

Statement

Reference

Complementation and Rescue Data

Comments

Images (0)

Mutant

Wild-type

Stocks (0)

Notes on Origin

Discoverer

Separable from: a second site lethal mutation (causing homozygous embryonic lethality) on the same chromosome.

(Mengoli et al., 2014)

External Crossreferences and Linkouts ( 0 )

Synonyms and Secondary IDs (2)

Reported As

Symbol Synonym

Top2^suo3

(Mengoli et al., 2014)

suo³

(Mengoli et al., 2014)

Name Synonyms

Secondary FlyBase IDs

References (1)

Report Sections

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