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General Information
D. melanogaster
Compound (1) Reversed Metacentric
FlyBase ID
Also Known As
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
Transposon Insertions
Formalized genetic data
Genetic mapping information
Comments on Cytology

C(1)RM, +.+; two X chromosomes in normal sequence attached proximally to the same centromere

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
NOT in combination with other aberrations

Recombination with the Y chromosome leads to detachments with a frequency of about 10-3 in C(1)RM/Y females. Has been extensively used in studies of crossing over (e.g., Anderson, 1925, Genetics 10: 403-17; Beadle and Emerson, 1935, Genetics 20: 192-206; Welshons, 1955, Genetics 40: 918-36).

Stocks (331)
Notes on Origin

L. V. Morgan, 12th Feb. 1921.


Recurs regularly by exchange between the heterochromatin of the short arm of one X, XYS, or XYL that of the base of the long arm of a sister or homolog. Can be induced in mature X.YL -bearing sperm (Leigh, 1972, DIS 48: 107). Presumably the pericentric heterochromatic constitutions of independently arising C(1)RM chromosomes varies.

Balancer / Genotype Variants of the Aberration
Separable Components
Other Comments

Attached X chromosomes homozygous for various w alleles were used to study dosage compensation of w.

Exists with many combinations of markers.

Synonyms and Secondary IDs (6)
Reported As
Name Synonyms
Compound (1) Reversed Metacentric
Secondary FlyBase IDs
    References (28)