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General Information
D. melanogaster
FlyBase ID
Feature type
Also Known As
γ238, Dpγ238
Computed Breakpoints include
Sequence coordinates
Member of large scale dataset(s)
Nature of Aberration
Cytological Order
Class of aberration (relative to wild type)
Class of aberration (relative to progenitor)
Causes alleles
Carries alleles
Transposon Insertions
Formalized genetic data

bk1 << p1:bk1 << p1:bk2 << bk2

Genetic mapping information
Comments on Cytology

Heterochromatic breakpoint is within the centromere, approximately 3kb inside the right end of Maupiti. Neocentromere-containing fragments are recovered from Dp(1;f)γ238 after γ-irradiation.

Used in experiments that showed that efficient achiasmate homolog disjunction in female meiosis I requires 1000kb of overlap in the centric heterochromatin and is not affected by homologous euchromatin or overall size differences. Disjunction efficiency decreases linearly as heterochromatic overlap is reduced from 1000 to 430kb. Rescue experiments with nod transgenes showed that heterochromatin does not act solely to promote chromosome movement or spindle attachment. Centric heterochromatin seems to contain multiple pairing elements that act additively to initiate or maintain the proper alignment of achiasmate chromosomes in meiosis I.

Sequences between -30kb and +800kb have been inverted, moving the ry marker genes to the other end of the chromosome.

830kb inversion between position -30 in the euchromatin to position +800 in the heterochromatin of the Dp(1;f)1187 derivative Dp1187-8-23, where position 0 is the In(1)sc8 inversion breakpoint.

Sequence Crossreferences
DNA sequence
Protein sequence
Gene Deletion and Duplication Data
Genes Deleted / Disrupted
Complementation Data
Completely deleted / disrupted
Partially deleted / disrupted
Molecular Data
Completely deleted
Partially deleted
Genes NOT Deleted / Disrupted
Complementation Data
Molecular Data
Genes Duplicated
Complementation Data
Completely duplicated
Partially duplicated
Molecular Data
Completely duplicated
Partially duplicated
Genes NOT Duplicated
Complementation Data
Molecular Data
Phenotypic Data
In combination with other aberrations

The presence of a second minichromosome significantly suppresses terminal deficiency-associated y PEV, this is termed 'trans-suppression'. Trans-suppression does not involve cross-homologue communication between transcription regulatory elements (transvection), nor is it accomplished by titration of heterochromatic factors through the addition of extra centric heterochromatin. Data indicates trans-suppression requires structural homology between two minichromosomes, suggesting pairing is required.

NOT in combination with other aberrations

Transmission rate through females to progeny is 54% in the first 5 days of egg lay.

Transmitted from meiosis at 49% in nod3/nod+ females and 53% in wild type females.

y PEV phenotype, partially suppressible by extra Y chromosome.

Stocks (0)
Notes on Origin
Balancer / Genotype Variants of the Aberration
Separable Components
Other Comments

Acentric mini-chromosomes are lost at a moderate but elevated rate during male germline mitotic divisions and in female mitosis, but appear to be transmitted efficiently through pre-blastoderm mitoses and male meiosis. mit(1)15 can localise to the mini-chromosome.

Large inversion of centric heterochromatin, one breakpoint located just distal to y and the other within centric heterochromatin.

Monosome transmission behaviour from both male and female parents is stable demonstrating normal transmission and normal centromere function.

Synonyms and Secondary IDs (3)
References (18)