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General Information
Symbol
Dp(1;f)1187
Species
D. melanogaster
Name
FlyBase ID
FBab0003287
Feature type
Also Known As
Dp1187, Dp(1;f)8-23
Computed Breakpoints include

1B2;h26-h32

Duplicated Segment
Sequence coordinates
Member of large scale dataset(s)
Nature of Aberration
Cytological Order
Mutagen
Class of aberration (relative to wild type)
Class of aberration (relative to progenitor)
Breakpoints
Causes alleles
Carries alleles
Transposon Insertions
Formalized genetic data

ac << bk1 << bb << bk2

Genetic mapping information
Comments

45 insertions of P{ry+,lacZ} into Dp(1;f)1187 fell into the same 4.7kb hot spot of repeated DNA that demonstrates properties of heterochromatin.

1300 kb (Karpen and Spradling, 1990, Cell 63: 97-107; Karpen and Spradling, unpublished)

Comments on Cytology

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.

Ref: Karpen and Spradling, 1990, Cell 63: 97--107.

Deletion results from breaks in the proximal and distal heterochromatin, exact location of the breakpoints is unknown. Coordinate 0 is the location of the existing In(1)sc8 breakpoint. ewg is present between coordinates -92 to -100, y between coordinates -20 to -25 and ac between coordinates -10 to -13.

Limits of break 1 from polytene analysis (FBrf0055832) Left limit of break 2 from inclusion of bb (citation unavailable) Right limit of break 2 from polytene analysis (FBrf0055832)

Sequence Crossreferences
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
Partially duplicated
Molecular Data
Completely duplicated
Partially duplicated
Genes NOT Duplicated
Phenotypic Data
In combination with other aberrations

Males carrying In(1)l-v231 and the free duplication Dp(1;f)1187 are only 6% as viable as controls.

The X heterochromatin in Dp(1;f)1187 appears to suppress the eye colour variegation phenotype of In(1)wm4.

The X heterochromatin in Dp(1;f)1187 appears to suppress the eye colour variegation phenotype of In(2)bwVde2.

The position effect variegation at the y locus caused by Dp(1;f)1187 is suppressed by Df(3R)Ace-HD1.

NOT in combination with other aberrations

The position effect variegation at the y locus caused by Dp(1;f)1187 is enhanced by Su(var)3-7+t6.5.

Variegated y phenotype scored by percentage of yellow bristles observed on the medial triple row at the anterior wing margin.

Variegated y phenotype, can be dominantly enhanced by mutations of E2f.

Transmission of the Dp(1;f)1187 minichromosome is sensitive to the dosage of nod+. Multiple regions of Dp(1;f)1187 interact with nod+ to promote normal chromosome transmission. Most nod+ interactions are observed with regions that are not essential for centromere function.

Assorts randomly with respect to sex chromosomes

Stocks (2)
Notes on Origin
Discoverer

Krivshenko and Cooper, 1953.

 

deletion of most of X euchromatin

Balancer / Genotype Variants of the Aberration
Separable Components
 
Other Comments
 

Length at mitotic metaphase (relative to length of 4th chromosome): 0.3 Frequency (%) of Dp/Y segregation among female progeny: 46.3 +- 1.19 (significant at 1% level of risk)

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.

The structure of heterochromatic DNA is altered as a general consequence of polyploid chromosome formation and the shortened molecules (restriction fragments that extend into the centric heterochromatin of Dp(1;f)1187) form as a consequence of heterochromatic underrepresentation. Alteration of heterochromatic DNA structure on Dp(1;f)1187 is not correlated with changes in the variegated expression of the y gene located on the minichromosome.

Irradiation mutagenesis and pulse-field restriction mapping reveals significant amounts of substructure deep within centric heterochromatin. Heterochromatin in general is organised as alternating blocks of complex islands and satellite DNA, each hundreds of kilobases in length. Islands of DNA have been called Tahiti Moorea and Bora Bora. Tahiti has been cloned and sequences which revealed the presence of a Doc{}ry-OreR transposon.

Centric heterochromatin contains islands of complex DNA (Tahiti, Moorea and Bora Bora) separated by blocks composed predominantly of highly repeated satellite DNA. Sequences necessary and sufficient for centromere activity during cell division reside in the island Bora Bora.

Satellite DNA carried on the chromosome is not involved in the hybrid lethality from the cross between D.melanogaster males and females of its sibling species.

While investigating the copy number of Dp(1;f)1187 sequences in the polyploid chromosome of ovarian nurse and follicle cells it was discovered that restriction fragments of genomic DNA spanning the euchromatic-heterochromatin junction have the unusual property of being selectively resistant to transfer out of agarose gels during Southern blotting, leading to systematic reductions in Dp(1;f)1187-specific hybridisation signals. Evidence is consistent with the hypothesis that pericentromeric sequences that are incorporated into heterochromatin in vivo retain some component of heterochromatic structure during DNA isolation which subsequently causes the reduced transfer efficiency observed in vitro.

Hybrids from the cross D.melanogaster C(1;Y)10/Dp(1;f)1187 males and D.sechellia females are viable.

DNA from the euchromatic/heterochromatic junction region demonstrates a significant gradient of underreplication in larval salivary glands, lacked the stalled replication forks predicted by the underreplication model. Therefore underreplication is not the mechanism of heterochromatin underrepresentation.

Induce low frequency of X and 4th chromosome nondisjunction.

A strong long range position-effect on polytenization of euchromatin is seen. Reduced copy number probably contributes to gene dysfunction or alterations at the level of DNA metabolism cause some variegation position effects. Chromosome length is 1400kb, 1/25 size of a normal X chromosome. Euchromatin spans 320-400kb, the first 90kb of heterochromatin is distal and the remaining 1000kb is proximal.

Synonyms and Secondary IDs (7)
References (82)