Localization of Telomeric Sequences in the Chromosomes of Three Species of Calomys (Rodentia, Sigmodontinae) (original) (raw)
Related papers
Chromosomal localization of telomeric sequences in three species of Akodon (Rodentia, Sigmodontinae)
Cytogenetic and Genome Research, 2004
The distribution of the vertebrate telomeric sequence T2AG3 in three species of the rodent genus Akodon was examined by FISH with a peptide nucleic acid probe. In addition to the expected telomeric hybridization, non-telomeric signals were observed in the three species. In A. dolores, centromeric signals were visible in two of the four biarmed autosome pairs featuring Robertsonian polymorphism, indicating the retention of at least part of the telomeric sequences during the fusion process, and an interstitial signal of lower intensity was observed in the short arm of another. In A. boliviensis, a strong signal was observed near the centromeric end of the first chromosome pair. The first pair of A. azarae (homologous to the first pair of A. boliviensis) showed a similar but markedly amplified signal, and a subcentromeric signal in the X chromosome corresponding to a heterochromatic region; additionally, interstitial signals of lower intensity were present in one to four chromosomes in...
Genetica, 2014
Characidium comprises several species of small freshwater fish that display conserved diploid chromosome numbers and karyotypic formulae. In this study, a comparative cytogenetic analysis using telomeric DNA probes was carried out in nine species of Characidium; a molecular phylogenetic analysis with mitochondrial DNA was also performed in order to investigate the direction of the evolutionary chromosome changes observed here. Our results showed the existence of species with several and variable interstitial telomeric sites (ITSs), with other species showing only terminal signals in their chromosomes. Molecular phylogenetic data suggested that these ITSs emerged once in the evolutionary history of Characidium and were later differentially spread in distinct species/ populations of this clade. Additionally, the origin of an exclusive acrocentric pair found in C. pterostictum, C. serrano and C. timbuiense was also investigated, revealing that this pair possibly had a common origin to these species. These results evidence the occurrence of intense and continuous genomic changes among species of Characidium.
Caryologia, 1999
In order to characterise the telomeric repeats of the pufferfish Tetraodon fluviatilis, fluorescent in situ hybridization (FISH) was carried out on metaphase chromosomes using a PCR generated probe (TTAGGG) n . Distinct signals have been observed on the tel-omeres of all the chromosomes and hybridization signals appears of uniform size and intensity. Moreover FISH experiment does not evidence any interstitial non-telomeric signal. As non-telomeric FISH signal has been used as a marker for karyotype evolution and for determining the evolutionary status of fish species, it could be supposed that the absence of non telomeric signals makes T. fluviatilis (Tetraodontiformes) an evolutionary ancient species in respect to Perciformes.
Chromosome Research, 2013
Rodentia comprises 42 % of living mammalian species. The taxonomic identification can be difficult, the number of species currently known probably being underestimated, since many species show only slight morphological variations. Few studies surveyed the biodiversity of species, especially in the Amazon region. Cytogenetic studies show great chromosomal variability in rodents, with diploid numbers ranging from 10 to 102, making it difficult to find chromosomal homologies by comparative G banding. Chromosome painting is useful, but only a few species of rodents have been studied by this technique. In this study, we sorted whole chromosome probes by fluorescence-activated cell sorting from two Hylaeamys megacephalus individuals, an adult female (2n=54) and a fetus (2n=50). We made reciprocal chromosome painting between these karyotypes and cross-species hybridization on Cerradomys langguthi (2n=46). Both species belong
Chromosome Research, 2005
The distribution of the vertebrate telomeric sequence (TTAGGG) n in four species of armadillos (Dasypodidae, Xenarthra), i.e. Chaetophractus villosus (2n = 60), Chaetophractus vellerosus (2n = 62), Dasypus hybridus (2n = 64) and Zaedyus pichiy (2n = 62) was examined by FISH with a peptide nucleic acid (PNA) probe. Besides the expected telomeric hybridization, interstitial (centromeric) locations of the (TTAGGG) n sequence were observed in one chromosome pair of Chaetophractus vellerosus and Zaedyus pichiy, suggesting chromosome fusion of ancestral chromosomes occurring during the evolution of Dasypodidae. In addition, all the species analysed showed one to four apparently telocentric chromosomes, exhibiting only two telomeric signals. However, the immunodetection study of kinetochore proteins on synaptonemal complex spreads from C. villosus showed that the apparently telocentric chromosomes have a tiny short arm that can be resolved only in the more elongated pachytene bivalents. This finding suggests that none of the species of armadillos possess true telocentric chromosomes. Our present results support a reduction in the diploid number by fusion of acrocentrics with loss of chromosome material as a tendency in Dasypodidae.
Cytogenetic and Genome Research, 2006
Comparative studies among four species – Akodonazarae (2n = 38), A. lindberghi (2n = 42), A. paranaensis (2n = 44) and A. serrensis (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:A. azarae, A. lindberghi and A. serrensis. One interstitial telomeric site (ITS) was observed proximally at the long arm of chromosome 1 of A. azarae. 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 A. lindberghi and A. serrensis were not related to chromosomal rearrangements; instead, the sequences co-localized with (i) heterochromatic regions of all chromosomes in A. serrensis; (ii) some heterochromatic regions in A. lindberghi, and (iii) both euchromatic and heterochromatic regions in the metacentric pai...
Cytologia 72(2): 165–171, 2007
2007
The distribution of telomeric sequences in 3 species of the phyllotine genus Calomys, whose members are distributed through an extensive area of South America, were analyzed by FISH with a PNA probe. C. musculinus, with a highly reordered karyotype with respect to other species of the genus, and C. venustus only showed fluorescent signals in a telomeric position. C. laucha, on the other hand, presented in addition a remarkable set of internal telomeric signals (ITS). ITS were seen constantly in the centromeric regions of biarmed pairs 1 and 2 and the X chromosome of this species, being the latter signal formed by 2 separated marks. On the basis of previous karyotypic information, these constant signals are interpreted as resulting from rearrangements occurred during karyotypic evolution. Additional signals of generally lower intensity were observed with different frequencies in up to 6 subterminal chromosomes of this species.
Hereditas, 2003
Ctenomys is the most numerous genus of South American subterranean rodents and one of the most karyotypically diverse clades of mammals known. Ctenomys magellanicus is the southernmost species of the group and the only one living in Isla Grande de Tierra del Fuego (Argentina). This species presents two chromosomal forms, i.e. 2n=34, and 2n=36 (FN=68). Recent studies suggest that genetic divergence between both karyotypic forms resulted from a chromosomal speciation process. In order to identify the chromosomal rearrangement involved in the process of karyotype evolution in this species, we used chromosome banding techniques and fluorescence in situ hybridization with a telomeric probe to metaphase chromosomes of the two chromosomal forms of Ctenomys magellanicus. Chromosome analysis of Giemsa-stained and G-banding preparations showed that Cm34 and Cm36 karyotypes differ in one rearrangement involving chromosomes A9 from Cm34 and B12 and B17 from Cm36. In addition FISH analysis showe...
The Journal of heredity, 2012
We studied the chromosomal distribution of telomere repeats (TTAGGG) n in 8 species of Sigmodon (cotton rats) using chromosome paints fluorescent in situ hybridization (FISH) from Sigmodon hispidus. In 2 species with the proposed primitive karyotype for the genus, telomere repeats were restricted to telomeric sites. But in the other 6 species that include 3 with proposed primitive karyotypes and 3 with highly rearranged karyotypes, telomere repeats were found on both telomeric sites and within interstitial telomeric sites (ITSs). To explain the distribution of ITS in Sigmodon, we gather data from C-bands, silver nitrate staining, G-bands, and chromosomal paint data from previous published studies. We did find some correlation with ITS and heterochromatin, euchromatic chromosomal rearrangements, and nucleolar organizing regions. No one type of chromosomal structure explains all ITS in Sigmodon. Multiple explanations and mechanisms for movement of intragenomic sequences are required to explain ITS in this genus. We rejected the hypothesis that age of a lineage correlates with the presence of ITS using divergence time estimate analyses. This multigene phylogeny places species with ITS (S. arizonae, S. fulviventer, S. hispidus, S. mascotensis, S. ochrognathus, and S. toltecus) in the clade with a species without ITS (S. hirsutus). Lineages with ITS (S. arizonae and S. mascotensis) arose independently from a lineage absent of ITS (S. hirsutus) around 0.67 to 0.83 Ma. The rearranged karyotypes of S. mascotensis and S. arizonae appear to be an independently derived autapomorphic characters, supporting a fast rate of chromosomal changes that vary among species.