Phylogenetic inferences of Atelinae (Platyrrhini) based on multi-directional chromosome painting in Brachyteles arachnoides, Ateles paniscus paniscus and Ateles b. marginatus

We performed multi-directional chromosome painting in a comparative cytogenetic study of the three Atelinae species Brachyteles arachnoides, Ateles paniscus paniscus and Ateles belzebuth marginatus, in order to reconstruct phylogenetic relationships within this Platyrrhini subfamily. Comparative chromosome maps between these species were established by multi-color fluorescence in situ hybridization ( FISH) employing human, Saguinus oedipus and Lagothrix lagothricha chromosome-specific probes. The three species included in this study and four previously analyzed species from all four Atelinae genera were subjected to a phylogenetic analysis on the basis of a data matrix comprised of 82 discrete chromosome characters. The results confirmed that Atelinae represent a monophyletic clade with a putative ancestral karyotype of 2n = 62 chromosomes. Phylogenetic analysis revealed an evolutionary branching sequence \{Alouatta \{Brachyteles \{Lagothrix and Ateles\}\}\} in Atelinae and \{Ateles belzebuth marginatus \{Ateles paniscus paniscus \{Ateles belzebuth hybridus and Ateles geoffroyi\}\}\} in genus Ateles. The chromosomal data support a re-evaluation of the taxonomic status of Ateles b. hybridus. Copyright (C) 2005 S. Karger AG, Basel

Low rate of genomic repatterning in Xenarthra inferred from chromosome painting data

Comparative cytogenetic studies on Xenarthra, one of the most basal mammalian clades in the Placentalia, are virtually absent, being restricted largely to descriptions of conventional karyotypes and diploid numbers. We present a molecular cytogenetic comparison of chromosomes from the two-toed (Choloepus didactylus, 2n = 65) and three-toed sloth species (Bradypus tridactylus, 2n = 52), an anteater (Tamandua tetradactyla, 2n = 54) which, together with some data on the six-banded armadillo (Euphractus sexcinctus, 2n = 58), collectively represent all the major xenarthran lineages. Our results, based on interspecific chromosome painting using flow-sorted two-toed sloth chromosomes as painting probes, show the sloth species to be karyotypically closely related but markedly different from the anteater. We also test the synteny disruptions and segmental associations identified within Pilosa (anteaters and sloths) against the chromosomes of the six-banded armadillo as outgroup taxon. We could thus polarize the 35 non-ambiguously identified chromosomal changes characterizing the evolution of the anteater and sloth genomes and map these to a published sequence-based phylogeny for the group. These data suggest a low rate of genomic repatterning when placed in the context of divergence estimates based on molecular and fossil data. Finally, our results provide a glimpse of a likely ancestral karyotype for the extant Xenarthra, a pivotal group for understanding eutherian genome evolution. © Springer 2005.Articl

Karyotypic analysis of Baryancistrus

Three specimes of Baryancistrus aff. niveatus were studied cytogenetically by conventional staining, C banding, Ag-NORs, CMA3, DAPI and FISH with human telomeric probes. The results revealed a complement consisting of 52 metacentric, submetacentric and subtelocentric type chromosomes. C banding showed that heterochro-matin is located at pairs 1, 3, 6, 10, 11 and 22 in different positions. NORs were located at the short arm of pair 3, coinciding with a positive C-band. This region was also marked with CMA3, which also marked heterochromatic blocks in chromosomes 11 and 22. These regions were negatively stained by DAPI. These results revealed the presence of two different types of constitutive heterochromatin, probably due to their base composition. Chromosome bearing rDNA sites presented a difference in size in the NOR regions, probably due to heterochromatin and ribos-somal cistrons amplification. The localization of telomeric sequences by FISH revealed the conservative nature of this region. © 2004 Taylor & Francis Group, LLC

Cytogenetic analysis on Pterophyllum scalare

Cytogenetic studies were carried out on eighteen wild specimens of Pterophyllum scalare from Jari River, in Pará state, and the results were compared to literature. Mitotic chromosomes were obtained from kidney cells and the analysis was done using: C-banding, Ag-NOR staining, Chromomycin A3/DAPI sequential staining and fluorochrome in situ hybridization with human telomere probes. All individuals showed a chromosome number of 2n = 48 (12 M/SM and 36 ST/A) and FN = 60. No differences were detected between male and female karyotypes, indicating the absence of morphologically differentiated mitotic sexual chromosomes. Constitutive heterochromatin blocks were located at the centromeric and pericentromeric regions of all chromosomes. The largest submetacentric pair showed a differential staining on their short arms. Only two NOR bearing chromosomes were detected, and the stainings were observed at the distal region of the short arm of the largest chromosome pair, matching the secondary constriction. Chromomycin A3, stained the NOR and the centromeres of some chromosomes. DAPI-bands were observed at the centromeric regions of all chromosomes. Telomere sequences hybridised only at the terminal regions. © 2006 Taylor and Francis Group, LLC

Chromosome comparison between two species of Phyllostomus (Chiroptera - Phyllostomidae) from Eastern Amazonia, with some phylogenetic insights

The karyotypes of Phyllostomus discolor and P. hastatus from Eastern Amazonia were studied by G-, C-, G/C sequential and Ag-NOR techniques. Both species presented 2n = 32, with the autosome complement composed of 30 bi-armed in P. discolor and 28 bi-armed plus 1 acrocentric in P. hastatus. In both species, the X chromosome is medium submetacentric while the Y is minute acrocentric. The present study found only one difference between the karyotypes of P. discolor and P. hastatus: the smallest autosome (pair 15) is bi-armed in discolor and acrocentric in hastatus, a result best explained by pericentric inversion. The C-banding revealed constitutive heterochromatin only at the centromeric regions of all chromosomes, with the NOR site located at the distal region of short arm of pair 15, in both species. The taxon P. discolor is considered primitive for genus Phyllostomus and the bi-armed form of pair 15 is the assumed primitive condition which, rearranged by a pericentric inversion originated the acrocentric from found in P. hastatus.<br>Os cariótipos de Phyllostomus discolor e P. hastatus da Amazônia oriental são estudados por bandeamentos G, C, G/C sequencial e coloração Ag-NOR. Ambas as espécies apresentaram 2n = 32, sendo o complemento autossômico composto por 15 pares bi-armed em P. discolor e 14 bi-armed mais 1 par acrocêntrico em P. hastatus. O cromossomo X é um submetacêntrico médio e o Y é um pequeno acrocêntrico em ambas as espécies. O presente estudo encontrou apenas uma diferença entre os cariótipos de P. discolor e P. hastatus: o menor autossomo (par 15) é metacêntrico em discolor e acrocêntrico em hastatus. Este resultado é melhor explicado por uma inversão pericêntrica. O bandeamento C revelou heterocromatina constitutiva na região centromérica de todos os cromossomos, e os sítios NOR foram localizados na região distal do par 15, em ambas as espécies. O táxon P. discolor é considerado primitivo para o gênero Phyllostomus e supõe-se que a forma metacêntrica do par 15 seja a condição primitiva, que foi rearranjada por uma inversão pericêntrica, originando a forma acrocêntrica encontrada em P. hastatus