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General Information
D. melanogaster
FlyBase ID
Feature type
Associated gene
Associated Insertion(s)
Carried in Construct
Also Known As
Su(var)2-504, Su(var)20504, Su(var)2-54
Key Links
Allele class
Nature of the Allele
Allele class
Mutations Mapped to the Genome
Additional Notes
Nucleotide change:


Reported nucleotide change:


Amino acid change:

K169term | Su(var)205-PA; K169term | Su(var)205-PB

Reported amino acid change:


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

Nonsense mutation in the C-terminal domain leading to deletion of the domain required for its localisation to the nucleus.

Amino acid replacement: K169term.

Nucleotide substitution: A1201T.

Expression Data
Reporter Expression
Additional Information
Marker for
Reflects expression of
Reporter construct used in assay
Human Disease Associations
Disease Ontology (DO) Annotations
Models Based on Experimental Evidence ( 0 )
Modifiers Based on Experimental Evidence ( 0 )
Comments on Models/Modifiers Based on Experimental Evidence ( 0 )
Disease-implicated variant(s)
Phenotypic Data
Phenotypic Class
Phenotype Manifest In
Detailed Description

Su(var)2054 partially suppresses the abdominal body or eye pigmentation variegation induced by P{SUPor-P}KV00135, P{SUPor-P}KV00108 or P{SUPor-P}KV00590.

Severe neuroblast loss is seen in the brains of Su(var)2054/Su(var)2055 mutant larvae. Many of the remaining neuroblasts exhibit necrosis markers, including aggregation of mitochondria and the presence of ubiquitin-conjugated protein aggregates.

Su(var)2054 suppresses the position effect variegation of the w gene that is seen in the P{hsp26-pt-T}Dyrk3118E-15 insertion.

One copy of Su(var)2054 strongly suppresses position effect variegation (PEV) at the w locus caused by In(1)wm4.

One copy of Su(var)2054 is unable to suppress the telomeric position effect (TPE) in stocks carrying a variegating P{hsp26-pt-T}39C-5 insertion at the telomere of the left arm of chromosome two.

Polytene chromosomes of Su(var)2054/Su(var)2055 larvae partly lose the distinct pattern of band-interband regions, especially in the male X chromosome.

Su(var)2052/Su(var)2054 mutant third instar larvae have melanotic nodules.

The X chromosome is bloated in polytene chromosome squashes from male Su(var)2054/Su(var)2055 third instar larvae.

Larval imaginal discs of Su(var)2054/Su(var)2055 mutants exhibit extensive apoptosis. Telomeres in Su(var)2054 heterozygous strains are elongated with respect to the wild-type phenotype. In comparison with wild-type telomeres, the telomeres from Su(var)2054 heterozygous strains show an increase in HeT-A sequences and a terminal addition of TART-element sequences. Multiple telomere fusions are seen in metaphase neuroblasts of Su(var)2054/Su(var)2055 larvae.

Su(var)2054 has no effect on the telomeric position effect (TPE) of P{hsp26-pt-T}39C-5 or P{hsp26-pt-T}39C-27.

Su(var)2054/Su(var)2055 larval mitotic chromosomes show telomeric fusions.

Heterozygotes show no effect on crossing over between kni and pp.

Neuroblasts in the brain of Su(var)2051/Su(var)2054 or Su(var)2054/Su(var)2055 larvae show a high frequency of abnormal metaphase configurations, including telomere-telomere fusions. The imaginal discs of Su(var)2054/Su(var)2055 larvae are reduced in size. Abnormal metaphase configurations showing telomeric fusions are seen in imaginal disc cells. Abnormal meiotic chromosomes are seen in the male germline.

Homozygous embryos are found to be mostly devoid of intact nuclei. Any remaining nuclei have defects in chromosome segregation and abnormal morphology (chromatin bridges, chromosome lagging during anaphase and under- or over-condensed nuclei). Mitotic synchrony is lost in a high proportion of embryos and defective nuclei are seen beneath the normal plane of nuclei, they appear to be falling into the interior of the embryo.

mod(mdg4)neo129 suppresses the strong dominant suppressor effect.

homozygous lethal

External Data
Show genetic interaction network for Enhancers & Suppressors
Phenotypic Class
Suppressed by
NOT suppressed by

Su(var)2055/Su(var)2054 has lethal phenotype, non-suppressible by JIL-1z2

NOT Suppressor of

Su(var)205[+]/Su(var)2054 is a non-suppressor of lethal | recessive phenotype of JIL-1z2

Phenotype Manifest In
Suppressed by
NOT suppressed by

Su(var)2055/Su(var)2054 has polytene chromosome phenotype, non-suppressible by JIL-1[+]/JIL-1z2

Enhancer of
NOT Suppressor of

Su(var)205[+]/Su(var)2054 is a non-suppressor of polytene chromosome phenotype of JIL-1z2

Additional Comments
Genetic Interactions

Flies carrying one copy of T(2;3)SbV frequently display a mosaic thoracic bristle phenotype, wherein bristles are both short and long, a phenotype that is enhanced by one copy of Su(var)2054.

Expression of fzyScer\UAS.cKa under the control of Scer\GAL4wor.PA suppresses the neuroblast loss seen in Su(var)2054/Su(var)2055 mutant larval brains. However, these surviving neuroblasts display phenotypes indicative of mitotic catastrophe including multinucleation and enlargement of cell diameter.

The Scer\GAL4GMR.PU, HersScer\UAS.T:Zzzz\FLAG rough eye phenotype is significantly enhanced by Su(var)2054.

In progeny from Su(var)2054 heterozygous females crossed to SxlfP7B0/Y males, female viability is dramatically reduced.

In progeny from Su(var)2054 heterozygous females crossed to Sxlf1/Y males, female viability is dramatically reduced.

The defects in polytene chromosome morphology seen in Su(var)2054/Su(var)2055 larvae are not altered by one copy of JIL-1z2.

The defects in polytene chromosome morphology seen in JIL-1z2 homozygous larvae are not altered by one copy of Su(var)2054 or Su(var)2055.

The polytene chromosome morphology of Su(var)2054/Su(var)2055 ; JIL-1z2/JIL-1z2 double mutants resembles that of JIL-1z2/JIL-1z2 single mutants.

When P{P-Sal}89D is present, the w gene of the P{lacW}ciDplac insertion variegates, resulting (in a w- background) in an eye that is mostly white with a few patches of red ommatidia. This P-element-dependent silencing of P{lacW}ciDplac is not dominantly suppressed by Su(var)2054.

Has no effect on the frequency of X-Y chromosome nondisjunction seen in Df(1)X-1-53B males.

Xenogenetic Interactions

Expression of Hsap\Cbx5hs.PN using daily heat shock in Su(var)2052/Su(var)2054 flies results in rescue of flies to adulthood (56% of the expected number of flies are rescued).

Complementation and Rescue Data
Fails to complement

The abnormal metaphase configurations seen in the brains of Su(var)2054/Su(var)2055 larvae are partly rescued by expression of Su(var)205hs.PE, although a high frequency of chromosome aberrations are seen.

Lethality is rescued by expression of the heat shock activated Su(var)205 construct. Rescued adults behave lethargically, walk slowly and never fly, and die several days after eclosion.

Images (0)
Stocks (2)
Notes on Origin
External Crossreferences and Linkouts ( 0 )
Synonyms and Secondary IDs (9)
References (53)