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Mapping the distribution of the interstitial telomeric (TTAGGG)_n sequences in eight species of Brazilian marsupials (Didelphidae) by FISH and the correlation with constitutive heterochromatin. Do ITS represent evidence for fusion events in American marsupials?

2002; Karger Publishers; Volume: 98; Issue: 4 Linguagem: Inglês

10.1159/000071049

1424-8581

J.M. Pagnozzi, Albert David Ditchfield, Yatiyo Yonenaga-Yassuda,

Primate Behavior and Ecology

The C-band pattern and the distribution of the (TTAGGG)_n sequence after fluorescence in situ hybridization (FISH), were studied in eight species of Didelphidae marsupials: four species with 2n = 14 <i>(Marmosops parvidens</i>, <i>Marmosops incanus</i>, <i>Marmosa murina</i> and <i>Metachirus nudicaudatus</i>), two species with 2n = 18 <i>(Monodelphis domestica</i> and <i>M. americana)</i>, and two with 2n = 22 (<i>Didelphis marsupialis</i> and <i>Lutreolina crassicaudata)</i>. The hybridization signals were observed at both termini telomeres of all chromosomes. In addition, interstitial sequences were detected in the pericentromeric region of all chromosomes of <i>Marmosops parvidens</i>, in five chromosome pairs of <i>M. incanus</i>, and in the first pair of <i>Monodelphis domestica</i>. These sites always occur in the region of constitutive heterochromatin, even though C-band positive regions do not always present interstitial telomeric sequences (ITS). We suggest that the interstitial (TTAGGG)_n sequences are associated with satellite DNA and do not necessarily arise through chromosomal rearrangements.