Chromosome study of Anteaters (Myrmecophagideae, Xenarthra): a preliminary report

Júnior, Hélio Rubens Jacintho Pereira; Jorge, W.; Costa, Maria E.

doi:10.1590/s1415-47572004000300014

Cited by 12 publications

(7 citation statements)

References 5 publications

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“…The chromosomes of Xenarthra are still poorly studied and most of the described karyotypes were analyzed after conventional staining, without banding patterns [28-30]. The diploid numbers in Xenarthra range from 2n = 38 in the armadillo Tolypeutes matacus to 2n = 65 in the sloth Choloepus didactylus [29,31].…”

Section: Introductionmentioning

confidence: 99%

Chromosome painting in three-toed sloths: a cytogenetic signature and ancestral karyotype for Xenarthra

et al. 2012

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BackgroundXenarthra (sloths, armadillos and anteaters) represent one of four currently recognized Eutherian mammal supraorders. Some phylogenomic studies point to the possibility of Xenarthra being at the base of the Eutherian tree, together or not with the supraorder Afrotheria. We performed painting with human autosomes and X-chromosome specific probes on metaphases of two three-toed sloths: Bradypus torquatus and B. variegatus. These species represent the fourth of the five extant Xenarthra families to be studied with this approach.ResultsEleven human chromosomes were conserved as one block in both B. torquatus and B. variegatus: (HSA 5, 6, 9, 11, 13, 14, 15, 17, 18, 20, 21 and the X chromosome). B. torquatus, three additional human chromosomes were conserved intact (HSA 1, 3 and 4). The remaining human chromosomes were represented by two or three segments on each sloth. Seven associations between human chromosomes were detected in the karyotypes of both B. torquatus and B. variegatus: HSA 3/21, 4/8, 7/10, 7/16, 12/22, 14/15 and 17/19. The ancestral Eutherian association 16/19 was not detected in the Bradypus species.ConclusionsOur results together with previous reports enabled us to propose a hypothetical ancestral Xenarthran karyotype with 48 chromosomes that would differ from the proposed ancestral Eutherian karyotype by the presence of the association HSA 7/10 and by the split of HSA 8 into three blocks, instead of the two found in the Eutherian ancestor. These same chromosome features point to the monophyly of Xenarthra, making this the second supraorder of placental mammals to have a chromosome signature supporting its monophyly.

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Section: Introductionmentioning

confidence: 99%

Chromosome painting in three-toed sloths: a cytogenetic signature and ancestral karyotype for Xenarthra

et al. 2012

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“…A new karyotype with 2n = 56 was recently reported in 1 male anteater from southeastern Brazil and suggested to belong to a still undescribed third species of Tamandua [Pereira Jr. et al, 2004]. On the other hand, Gardner [2008] suggested that this new complement is likely to be that of T .…”

Section: Anteatersmentioning

confidence: 99%

“…A summary of the available karyotypic data of Xenarthra is presented in table 1 . Chromosome rearrangements, such as pericentric inversions, Robertsonian fusions/fissions and heterochromatin additions/deletions, have been suggested to explain the karyotypic evolution in Xenarthra [Jorge et al, 1977[Jorge et al, , 1985aBarroso and Seuánez, 1991;Pereira et al, 2004]. Nevertheless, their occurrence remains speculative, as the suggestions were based on conventionally stained chromosomes or low resolution banding patterns.…”

Section: Classical Cytogenetics Of Xenarthramentioning

confidence: 99%

“…Considering the small number of individuals of each species analyzed, the fact that subspecies were attributed to each of them [Gardner, 2008] and the recent description of a new karyotype [Pereira Jr. et al, 2004], it is clear that additional karyotypic data on anteaters are likely to disclose new chromosome variations and that comparative cytogenetic analyses are needed in order to discuss the possible relationships among the different complements found in anteater species.…”

Section: Anteatersmentioning

confidence: 99%

“…This is mainly due to their rarity, restricted geographical distribution and poor sampling, which results from the difficulty in spotting them because they may be burrowers, as the armadillos, or dwell in forest canopies, as the sloths. The existence of undescribed taxa is also very likely [Pereira et al, 2004;Gardner, 2008;IUCN, 2011].…”

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Chromosome Evolution in Xenarthra: New Insights from an Ancient Group

Svartman

2012

Cytogenet Genome Res

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The Magnaorder Xenarthra is one of the four main supraordinal eutherian clades, together with Afrotheria, Euarchontoglires and Laurasiatheria. Xenarthra is an eminently Central and South American group of special interest in phylogenetic studies due to its possible position at the base of the eutherian tree. The use of modern cytogenetic techniques in some species of Xenarthra has provided important insights into the karyotypic evolution of mammals. Nevertheless, chromosome analyses in the group are still restricted, with only a few individuals of each species studied and karyotype descriptions mostly without banding patterns. In addition, it is likely that still unknown species exist and that the chromosome variability in the group is underestimated. We present a review of the currently available data on Xenarthra chromosomes and genomes and on the impact that their study has had in the understanding of mammalian genome evolution. It is clear that further cytogenetic analyses in Xenarthra, including banding patterns and molecular approaches, are likely to help in the identification of new species, reveal still undetected chromosome variations, provide information to support conservation strategies planning, and greatly contribute to a better understanding of mammalian genome evolution.

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Reconstruction of the Ancestral Xenarthran Karyotype

Svartman

2013

Encyclopedia of Life Sciences

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Xenarthra is the group of mammals that reunites anteaters, armadillos and sloths. According to the most recent phylogenetic schemes, Xenarthra is considered one of the four main supraordinal eutherian clades. This group, found in Central and South America, is considered especially important as it may be at the base of the eutherian tree. Although most cytogenetic studies in Xenarthra have been restricted to a few specimens and poor resolution techniques, recent chromosome painting analyses in some Xenarthra species resulted in important data regarding mammalian karyotypic evolution. An ancestral karyotype with 2 n =48 chromosomes has been recently proposed as ancestral to all Xenarthra. This complement is very similar to the 2 n =46 proposed as ancestral to all eutherian mammals, which may be a further indication of the basal phylogenetic position of Xenarthra in the eutherian tree. Key Concepts: Xenarthra is a Central and South American group of mammals represented by anteaters, armadillos and sloths. Xenarthra is phylogenetically important because of its likely basal position in the tree of eutherian mammals. In general, cytogenetic data on Xenarthra are restricted to a few specimens and to low resolution techniques. However, the recent use of molecular cytogenetics, namely chromosome painting, in Xenarthra has provided data that allowed the reconstruction of a hypothetical Xenarthra ancestral karyotype (XAK) with 2 n =48. The 2 n =48 XAK closely resembles the proposed ancestral eutherian karyotype (AEK) with 2 n =46, which further supports the idea that Xenarthra is basal to all eutherians.

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Chromosome study of Anteaters (Myrmecophagideae, Xenarthra): a preliminary report

Cited by 12 publications

References 5 publications

Chromosome painting in three-toed sloths: a cytogenetic signature and ancestral karyotype for Xenarthra

Chromosome painting in three-toed sloths: a cytogenetic signature and ancestral karyotype for Xenarthra

Chromosome Evolution in Xenarthra: New Insights from an Ancient Group

Reconstruction of the Ancestral Xenarthran Karyotype

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