Pericentric inversion and X chromosome polymorphism inRhipidomyssp. (Cricetidae, Rodentia) from Brazil

Svartman, Marta; Almeida, Eunice Judith Cardoso de

doi:10.1080/00087114.1993.10797262

Cited by 13 publications

(20 citation statements)

References 6 publications

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“…Thus, the differences in the number of the Ag-NORs per cell may reflect differences in the number of active ribosomal sites in the last interphase (THIRIOT-QUIÉVREUX & INSUA 1992, GALETTI et al 1995. This polymorphism in the number of active NOR sites per cell seems to be common in rodents and has been reported for other species (YONENAGA-YASSUDA et al 1992, SVARTMAN & ALMEIDA 1993, LIMA et al 2003, SOUZA et al 2007.…”

Section: Discussionmentioning

confidence: 99%

A new karyotype of Wiedomys pyrrhorhinus (Rodentia: Sigmodontinae) from Chapada Diamantina, northeastern Brazil

Souza¹,

Corrêa²,

Aguilar³

et al. 2011

Zoologia (Curitiba, Impr.)

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Section: Discussionmentioning

confidence: 99%

A new karyotype of Wiedomys pyrrhorhinus (Rodentia: Sigmodontinae) from Chapada Diamantina, northeastern Brazil

Souza¹,

Corrêa²,

Aguilar³

et al. 2011

Zoologia (Curitiba, Impr.)

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“…For example, in Nesokia indica it has been suggested that selective pressure favoring specimens with large blocks of constitutive heterochromatin in the X and Y chromosomes promoted reduction of fertility [Thelma et al, 1988;Juyal et al, 1989]. However, this is a debatable issue since polymorphism in the amount of constitutive heterochromatin in sex chromosomes is quite common in some rodent groups, including the sigmodontines Euryoryzomys, Oligoryzomys, Nectomys , and Rhipidomys , and the echimyids Trichomys and Clyomys Yonenaga-Yassuda, 1982, 1984;Leal-Mesquita et al, 1993;Svartman and Almeida, 1993;Yonenaga-Yassuda, 1997, 1998]. Therefore, the biological meaning of the variation of heterochromatin amounts between both species of Deltamys remains unclear for the moment.…”

Section: Discussionmentioning

confidence: 99%

A New Allopatric Lineage of the Rodent Deltamys (Rodentia: Sigmodontinae) and the Chromosomal Evolution in Deltamys kempi and Deltamys sp.

Ventura

Fagundes

D’Elı́a

et al. 2011

Cytogenet Genome Res

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Deltamys Thomas 1917 is a poorly studied and rarely collected taxon of Akodontini (Sigmodontinae). The single described species, Deltamys kempi (DKE), has a basic karyotype with a diploid number of 2n = 37 in males and 2n = 38 in females, a fundamental number FN = 38 for both sexes, and an X₁X₁X₂X₂/X₁X₂Y sex determination system. Herein, a new allopatric form, Deltamys sp. (DSP), is reported, based on specimens from southern Brazil, with 2n = 40, FN = 40 and XX/XY sex chromosomes. We describe the karyotype and mechanism of chromosomal differentiation between both Deltamys complements. Phylogenetic analyses, based on the complete sequence (1,140 bp) of the mitochondrial cytochrome b gene, grouped Deltamys sp. as sister species to D. kempi, with up to 12% genetic divergence between them. The GTG-banding patterns show complete autosomal correspondence between D. kempi and Deltamys sp. and identify a tandem rearrangement involving DSP7, DSP19 and DKE4 that is responsible for the differences in 2n and FN. Chromosome painting with Akodon paranaensis chromosome 21 (a small metacentric akodont marker) paint revealed total homology with the smallest acrocentric Deltamys sp. chromosome, DSP19. This suggests the occurrence of a pericentric inversion or centromeric shift when compared to other akodontines, with a posterior tandem rearrangement giving rise to DKE4. In DKE, large blocks of pericentromeric constitutive heterochromatin are present on the autosomes and the X, and the Y/autosome has an entirely heterochromatic short arm. In DSP, small heterochromatic blocks are observed on autosomes and X, and the Y is a very small, mostly heterochromatic acrocentric. The cytogenetic analyses suggest that the Deltamys sp. karyotype is ancestral, with the derived condition resulting from a tandem fusion (DSP7 + DSP19) and the Y/autosome translocation giving rise to the multiple sex chromosome system. The autosomal rearrangements, the differences in CBG-banding patterns and Ag-NOR localization, as well as the presence of X₁X₁X₂X₂/X₁X₂Y and XX/XY sex determination mechanisms, possibly acting as a reproductive barrier, and the phylogenetic position within the Deltamys genus, with high genetic divergence, call for a taxonomic review of the genus.

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“…Cytogenetic studies performed in one species from Colombia (Gardner and Patton 1976), 2 from Venezuela (Aguilera et al 1994), and in 8 from Brazil (Zanchin et al 1992, Svartman and Almeida 1993, Silva and Yonenaga-Yassuda 1999, showed that, with the exception of one, all species of this genus have the same diploid number (44), apparently differing among themselves only by the number of biarmed elements they carry (autosomal arms numbers ranging from 48 to 74).…”

Section: Introductionmentioning

confidence: 99%

“…Circles: Rhipidomys nitela; squares: R. leucodactylus cytotypes; lozenges: R. mastacalis cytotypes. Numbers 1, 5, 9 and 11 -this paper; 2, 7 and 8 -Silva and Yonenaga-Yassuda (1999); 3 -Aguilera et al (1994); 4 -Gardner and Patton (1976); 6, 13-16 -Zanchin et al (1992); 10 and 12 -Svartman and Almeida (1993).…”

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confidence: 99%

Genetic studies in representatives of genusRhipidomys (Rodentia, Sigmodontinae) from Brazil

et al. 2002

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2002. Genetic studies in representatives of genus Rhipidomys (Rodentia, Sigmodontinae) from Brazil. Acta Theriologica 47: 125-135. Karyotypic polymorphism of five taxa of the rodent genus Rhipidomys from the Brazilian Amazon and Cerrado biomes was analysed. Rhipidomys nitela Thomas, 1901 from Amazon has 2n = 48, FN = 68. The other species, all have 2n = 44, but can be separated into two groups, one with high FNs (76, 80) and the other with low FNs (48, 52). Two cytotypes of R. mastacalis (Lund, 1840) with high FNs were trapped in four localities of the Cerrado, showing 19 and 17 biarmed autosomes, respectively. A low FN (48) was observed in R. leucodactylus (Tschudi, 1844) in two localities of the Cerrado and FN = 52 in one locality in the Cerrado and the Amazon. All taxa with 2n = 44 have a medium-sized acrocentric X chromosome and a small Y. Rhipidomys nitela is different from the species with 2n = 44 by presenting a heterochromatic short arm of the X chromosome. In all karyotypes analysed, the nucleolus organizer regions were located in the short arms of two to six pairs and the (T 2 AG 3 ) n telomeric probes hybridized in situ in both the short and long arms of all pairs of the karyotypes.

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Pericentric inversion and X chromosome polymorphism inRhipidomyssp. (Cricetidae, Rodentia) from Brazil

Cited by 13 publications

References 6 publications

A new karyotype of Wiedomys pyrrhorhinus (Rodentia: Sigmodontinae) from Chapada Diamantina, northeastern Brazil

A new karyotype of Wiedomys pyrrhorhinus (Rodentia: Sigmodontinae) from Chapada Diamantina, northeastern Brazil

A New Allopatric Lineage of the Rodent <i>Deltamys</i> (Rodentia: Sigmodontinae) and the Chromosomal Evolution in <i>Deltamys kempi</i> and <i>Deltamys</i> sp.

Genetic studies in representatives of genusRhipidomys (Rodentia, Sigmodontinae) from Brazil

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