Complex evolution of X and Y autosomal translocations in the giant mole-rat, Cryptomys mechowi (Bathyergidae) |
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Authors: | J L Deuve N C Bennett P C M O’Brien M A Ferguson-Smith C G Faulkes J Britton-Davidian T J Robinson |
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Institution: | (1) Evolutionary Genetics Group, Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland, 7602, South Africa;(2) Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa;(3) Centre for Veterinary Science, University of Cambridge, Cambridge, UK;(4) School of Biological and Chemical Sciences, Queen Mary, University of London, London, UK;(5) Institut des Sciences de l’Evolution (UMR5554), Génétique & Environnement, Université Montpellier II, Montpellier, France |
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Abstract: | Cross-species chromosome painting was used to determine homologous chromosomal regions between two species of mole-rat, the
naked mole-rat, Heterocephalus glaber (2n = 60), and the giant mole-rat, Cryptomys mechowi (2n = 40), using flow-sorted painting probes representative of all but two of the H. glaber chromosomal complement. In total 43 homologous regions were identified in the C. mechowi genome. Eight H. glaber chromosomes are retained in toto in C. mechowi, and 13 produce two or more signals in this species. The most striking difference in the karyotypes of the two taxa concerns
their sex chromosomes. The H. glaber painting probes identified a complex series of translocations that involved the fractionation of four autosomes and the subsequent
translocation of segments to the sex chromosomes and to autosomal partners in the C. mechowi genome. An intercalary heterochromatic block (IHB) was detected in sex chromosomes of C. mechowi at the boundary with the translocated autosomal segment. We discuss the likely sequence of evolutionary events that has led
to the contemporary composition of the C. mechowi sex chromosomes, and consider these in the light of prevailing views on the genesis of sex chromosomes in mammals. |
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Keywords: | Cryptomys mechowi evolution giant mole-rat heterochromatin sex-autosome translocation X chromosome Y chromosome |
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