Title
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A new cytotype of the African pygmy mouse **Mus minutoides** in Eastern Africa : implications for the evolution of sex-autosome translocations
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Author
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Abstract
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The African pygmy mice (genus Mus, subgenus Nannomys) are recognized for their highly conserved morphology but extensive chromosomal diversity, particularly involving sex-autosome translocations, one of the rarest chromosomal rearrangements among mammals. It has been shown that in the absence of unambiguous diagnostic morphological traits, sex-autosome translocations offer accurate taxonomic markers. For example, in Mus minutoides, irrespective of the diploid number (which ranges from 2n = 18 to 34), all specimens possess the sex-autosome translocations (X.1) and (Y.1) that are unique to this species. In this study, we describe a new cytotype that challenges this view. Males are characterized by the translocation (Y.1) only, while females carry no sex-autosome translocation, the X chromosome being acrocentric. Hence, although sex-autosome translocations (X.1) and (Y.1) are still diagnostic when one or both are present, their absence does not rule out M. minutoides. This cytotype has a large distribution, with specimens found in Tanzania and in the eastern part of South Africa. The nonpervasive distribution of Rb(X.1) provides an opportunity to investigate different evolutionary scenarios of sex-autosome translocations using a phylogenetic framework and the distribution of telomeric repeats. The results tend to support a scenario involving a reversal event, i.e., fusion then fission of Rb(X.1), and highlighted the existence of a new X1X1X2X2/X1X2Y sex chromosome system, confirming the remarkable diversity of neo-sex chromosomes and sex determination systems in the African pygmy mice. |
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Language
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English
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Source (journal)
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Chromosome research : an international journal on the molecular supramolecular and evolutionary aspects of chromosome biology / Koninklijke Nederlandse Akademie van Wetenschappen [Amsterdam] - Oxford
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Publication
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Oxford
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2014
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ISSN
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0967-3849
[print]
1573-6849
[online]
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DOI
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10.1007/S10577-014-9440-X
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Volume/pages
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22
:4
(2014)
, p. 533-543
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ISI
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000345967900008
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Pubmed ID
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25159220
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Full text (Publisher's DOI)
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Full text (publisher's version - intranet only)
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