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Citation
Nurminsky, D.I., Shevelyov, Y.Y., Nuzhdin, S.V., Gvozdev, V.A. (1994). Structure, molecular evolution and maintenance of copy number of extended repeated structures in the X-heterochromatin of Drosophila melanogaster.  Chromosoma 103(4): 277--285.
FlyBase ID
FBrf0076047
Publication Type
Research paper
Abstract

The 60 kb repeats located in the distal heterochromatin of the X chromosome of Drosophila melanogaster were cloned in overlapping cosmids. These regions, designated as SCLRs, comprised the following types of repeated elements: Stellate genes, which are known to be involved in spermatogenesis; copia-like retrotransposons; LINE elements, including amplified Type I rDNA insertions; and rDNA fragments. The following steps in SCLR formation were hypothesized: insertion of mobile elements into the rDNA and Stellate gene clusters; internal tandem duplication events; recombination between the rDNA cluster and Stellate tandem repeat; and amplification of the whole SCLR structure. There are about nine SCLR copies per haploid genome, but there is approximately a twofold variation in copy number between fly stocks. The SCLR copy number differences between closely related stocks are suggested to be the result of unequal sister chromatid exchange (USCE). The restricted variation in SCLR copy number between unrelated stocks and the absence of chromosomes free of SCLRs suggests that natural selection is active in copy number maintenance.

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    Language of Publication
    English
    Additional Languages of Abstract
    Parent Publication
    Publication Type
    Journal
    Abbreviation
    Chromosoma
    Title
    Chromosoma
    Publication Year
    1939-
    ISBN/ISSN
    0009-5915
    Data From Reference
    Aberrations (5)
    Genes (4)
    Natural transposons (5)