Karyotypic evolution of hapalomys inferred from chromosome painting: a detailed characterization contributing new insights into the ancestral murinae karyotype.
We report on the construction of a comparative chromosome map between the emblematic laboratory rat, Rattus norvegicus (RNO), and Delacour's Marmoset rat, Hapalomys delacouri (HDE), based on cross-species fluorescence in situ hybridization with R. norvegicus painting probes. Sixteen R. norvegicus chromosomes (RNO 3-6, 8, 10-15, 17-20, and X) were retained in their entirety (as a conserved block or as a single chromosome) in the H. delacouri genome. The remaining 5 R. norvegicus chromosomes (RNO 1, 2, 7, 9, and 16) produced 2 signals in the H. delacouri karyotype. Our analysis allowed the detection of an X-autosome translocation between RNO X and 11 that occurred convergently in an unrelated species, Bandicota savilei, and a single B chromosome that accounts for the 2n = 48 karyotype observed in this specimen. In total, the rat chromosome paints revealed 27 segments of conserved synteny in H. delacouri. The analysis showed 7 NOR bearing pairs in H. delacouri (HDE 1, 3, 6, 7, 8, 10, and 13) and the occurrence of an interstitial telomeric signal at the centromeric regions of 8 H. delacouri chromosomes (HDE 3, 10, 11, 12, 13, 16, 19, and 22). These data, together with published comparative maps, enabled a revision of the previously postulated murine ancestral condition suggesting that it probably comprised a wholly acrocentric karyotype with 2n = 46-50.
Evolutionary Genomics Group, University of Stellenbosch, Botany and Zoology Department, Stellenbosch, South Africa.
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Badenhorst
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Dobigny
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Robinson
D000818:Animals; D002874:Chromosome Mapping; D020223:Chromosome Painting / Q000379:methods*; D033481:Chromosomes, Mammalian / Q000235:genetics; D019143:Evolution, Molecular; D059785:Karyotype; D007621:Karyotyping / Q000379:methods*; D051379:Mice; D051189:Murinae / Q000235:genetics*; D051381:Rats; D026801:Synteny