Journal Article

Characterization of Neo-Centromeres in Marker Chromosomes Lacking Detectable Alpha-satellite DNA

Theresa W. Depinet, Joleen L. Zackowski, William C. Earnshaw, Sara Kaffe, Gurbax S. Sekhon, Richard Stallard, Beth A. Sullivan, Gail H. Vance, Daniel L. Van Dyke, Huntington F. Willard, Arthur B. Zinn and Stuart Schwartz

in Human Molecular Genetics

Volume 6, issue 8, pages 1195-1204
Published in print August 1997 | ISSN: 0964-6906
Published online August 1997 | e-ISSN: 1460-2083 | DOI:
Characterization of Neo-Centromeres in Marker Chromosomes Lacking Detectable Alpha-satellite DNA

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Recent studies have implicated α-satellite DNA as an integral part of the centromere, important for the normal segregation of human chromosomes. To explore the relationship between the normal functioning centromere and α-satellite DNA, we have studied eight accessory marker chromosomes in which fluorescence in-situ hybridization could detect neither pancentromeric nor chromosome-specific α-satellite DNA. These accessory marker chromosomes were present in the majority of or all cells analyzed and appeared mitotically stable, thereby indicating the presence of a functional centromere. FISH analysis with both chromosome-specific libraries and single-copy YACs, together with microsatellite DNA studies, allowed unequivocal identification of both the origin and structure of these chromosomes. All but one of the marker chromosomes were linear mirror image duplications, and they were present along with either two additional normal chromosomes or with one normal and one deleted chromosome. Indirect immunofluorescence analysis revealed that the centromere protein CENP-B was not present on these markers; however, both CENP-C and CENP-E were present at a position defining a ‘neo-centromere’. These studies provide insight into a newly defined class of marker chromosomes that lack detectable α-satellite DNA. At least for such marker chromosomes, α-satellite DNA at levels detectable by FISH appears unnecessary for chromosome segregation or for the association of CENP-C and CENP-E at a functional centromere.

Journal Article.  5115 words.  Illustrated.

Subjects: Genetics and Genomics

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