Telomeres and mechanisms of Robertsonian fusion |
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Authors: | Predrag Slijepcevic |
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Institution: | (1) School of Biomedical Sciences, Bute Medical Buildings, University of St. Andrews, St. Andrews KY 16 9TS, UK, GB |
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Abstract: | The Robertsonian (Rb) fusion, a chromosome rearrangement involving centric fusion of two acro-(telo)centric chromosomes to
form a single metacentric, is one of the most frequent events in mammalian karyotype evolution. Since one of the functions
of telomeres is to preserve chromosome integrity, a prerequisite for the formation of Rb fusions should be either telomere
loss or telomere inactivation. Possible mechanisms underlying the formation of various types of Rb fusion are discussed here.
For example, Rb fusion in wild mice involves complete loss of p-arm telomeres by chromosome breakage within minor satellite
sequences. By contrast, interstitial telomeric sites are found in the pericentromeric regions of chromosomes originating from
a number of vertebrate species, suggesting the occurrence of Rb-like fusion without loss of telomeres, a possibility consistent
with some form of telomere inactivation. Finally, a recent study suggests that telomere shortening induced by the deletion
of the telomerase RNA gene in the mouse germ-line leads to telomere loss and high frequencies of Rb fusion in mouse somatic
cells. Thus, at least three mechanisms in mammalian cells lead to the formation of Rb fusions.
Received: 11 November 1997 / Accepted: 21 December 1997 |
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