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Non-telomeric sites as evidence of chromosomal rearrangement and repetitive (TTAGGG)_narrays in heterochromatic and euchromatic regions in four species of <i>Akodon</i> (Rodentia, Muridae)

2006; Karger Publishers; Volume: 115; Issue: 2 Linguagem: Inglês

10.1159/000095238

1424-8581

Karen Ventura, Maria José de Jesus Silva, Valéria Fagundes, Alexandre Uarth Christoff, Yatiyo Yonenaga-Yassuda,

Evolution and Paleontology Studies

Comparative studies among four species – <i>Akodon</i><i>azarae </i>(2n = 38), <i>A. lindberghi </i>(2n = 42), <i>A. paranaensis</i> (2n = 44) and <i>A. serrensis </i>(2n = 46) – employing classic cytogenetics (C- and G-bands) and fluorescence in situ hybridization with telomeric (TTAGGG)_n sequencesare reported here. Non-telomeric signals in addition to the regular telomeric sites were detected in three species:<i>A. azarae</i>, <i>A. lindberghi</i> and <i>A. serrensis</i>. One interstitial telomeric site (ITS) was observed proximally at the long arm of chromosome 1 of <i>A. azarae</i>. The comparison of G-banding patterns among the species indicated that the ITS was due to a tandem fusion/fission rearrangement. Non-telomeric signals of <i>A. lindberghi </i>and <i>A. serrensis </i>were not related to chromosomal rearrangements; instead, the sequences co-localized with (i) heterochromatic regions of all chromosomes in <i>A. serrensis</i>; (ii) some heterochromatic regions in <i>A. lindberghi</i>, and (iii) both euchromatic and heterochromatic regions in the metacentric pair of <i>A. lindberghi</i>. These exceptional findings revealed that ITS in <i>Akodon</i> can be related to chromosomal rearrangements and repetitive sequences in the constitutive heterochromatin and that the richness of TTAGGG-like sequences in the euchromatin could be hypothesized to be a result of amplification of the referred sequence along the chromosome arms.