Geographical variation of heterochromatin in &lt;i&gt;Ctenomys flamarion&lt;/i&gt;&lt;i&gt;i&lt;/i&gt; (Rodentia-Octodontidae) and its cytogenetic relationships with other species of the genus

Freitas, Thales Renato Ochotorena de

doi:10.1159/000133821

Cited by 47 publications

(34 citation statements)

References 8 publications

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“…These could be explained by the occurrence of extensive changes in the location of the Uruguay River bed (D'Elia et al 1999). Our data are consistent with Freitas (1994), who proposed the assignment of C. rionegrensis to the C. mendocinus group from Argentina based on chromosome and spermatic analysis. Subsequently, molecular studies of cytochrome b DNA variation of species of Ctenomys (from Uruguay, Argentina, Brazil, Bolivia, and Chile) are consistent with this assignment (D'Elia et al 1999).…”

Section: Discussionsupporting

confidence: 92%

G-banding patterns of the genusCtenomysfrom Uruguay (Rodentia Ctenomydae): high karyotype variation but chromosome arm conservation

2014

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The genus Ctenomys present a wide 2n and fundamental number (FN) variation in Uruguay and throughout their distribution across the south of the Neotropical region. In this study we analyze chromosome variation of this genus in Uruguay using G and C bands. G-band comparison makes clear that this chromosome variation is reduced if we take into account entire chromosomes and chromosome arms homologies. This could be explained as an adaptation to chromosome variation (2n and FN) without changing gene order or linkage groups. On the other hand, C-banding showed a high variability in amount and localization in the karyotypes analyzed here. These differences could be due to differential amplification of the repetitive DNA (RPSC) characteristic of this genus. Nevertheless, other mechanisms could be involved as repetitive DNA interchange at the chromocenters in the meiosis pachytene, where non homologous chromosomes meet. In this scenario, chromosome rearrangements such as Robertsonian translocations and whole chromosome conservation are of particular interest since these provide a way to conserve gene order. Why Ctenomys chromosomes are prone to rearrangements is not clear, albeit several mammal species present a similar picture. This kind of chromosome change could be involved in the maintenance of chromosome order at the nuclear level. In this paper, we present evidence showing that chromosome and genetic changes are not unavoidably related in Ctenomys, which questions the hypothesis about speciation based on chromosomal changes.

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Section: Discussionsupporting

confidence: 92%

G-banding patterns of the genusCtenomysfrom Uruguay (Rodentia Ctenomydae): high karyotype variation but chromosome arm conservation

2014

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“…Karyotypic differences in Ctenomys involve changes in chromosome morphology Novello and Altuna, 2002] and variations in heterochromatin amount and localization [Gallardo, 1991;Freitas, 1994;Rossi et al, 1995;Novello et al, 1996a, b;Novello and Villar, 2006]. In the populations surveyed here, 2n values and heterochromatin variation were observed, indicating a high degree of chromosome change.…”

Section: Discussionmentioning

confidence: 59%

“…chromosome pairs to karyotypes showing heterochromatic short arms in all chromosomes [Freitas, 1994;Rossi et al, 1995;Novello et al, 1996a, b]. The major satellite DNA of tuco-tucos, named RPCS (repetitive PuvII Ctenomys sequence) is organized in long arrays of 348 bpmonomer units [Rossi et al, 1990].…”

mentioning

confidence: 99%

Possible Heterochromatin Horizontal Spread through Non-Homologous Chromosome Associations in Pachytene Chromocenters of <i>Ctenomys </i>Rodents

Novello

Villar²,

Urioste³

2010

Cytogenet Genome Res

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Heterochromatin patterns were analyzed in the genus Ctenomys from Uruguay which exhibits high karyotype variability. Different amounts and localizations of heterochromatin were observed in species and populations analyzed. While species as C. rionegrensis presented heterochromatic arms in all the chromosomes of the karyotype, other species like C. torquatus showed only few chromosomes with pericentric heterochromatin. At the pachytene stage, bivalents merge in densely stained chromocenters. We detected in these chromocenters the typical highly repeated DNA of this genus after in situ hybridization, the M31 chromodomain through immunofluorescence as well as dense Giemsa staining after C-banding. In species that present low amounts of heterochromatin, only 1 or 2 chromocenters were observed in which bivalents merge as observed in C. rionegrensis. After BRCA1 immunodetection we observed in early pachytene cells positive spots located over heterochromatic chromocenters that strongly suggest heterochromatic DNA repair. Mechanical stress mainly due to increasing chromatin compactness before metaphase I might be a mechanism to spread heterochromatin between different chromosomes within a karyotype.

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“…D. leporina and Dasyprocta sp. presented the Y chromosome almost totally heterochromatic, as found in D. leporina (Lima 1993, Lima and Langguth 1995, 1998 and in some species from Ctenomys that presented Y chromosome varying from totally hete- rochromatic to C banding negative standard (Freitas 1994). D. prymnolopha, D. leporina and Dasyprocta sp.…”

Section: Discussionmentioning

confidence: 85%

Karyotypic analysis in species of the genus Dasyprocta (Rodentia: Dasyproctidae) found in Brazilian Amazon

Ramos¹,

Vale²,

Assis³

2003

An. Acad. Bras. Ciênc.

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A total of 30 animals of the genus Dasyprocta were cytogenetically studied. They belong to the following species: D. prymnolopha (N=20), D. leporina (N=6), D. fuliginosa (N=1) and Dasyprocta sp. (N=3) (Dasyproctidae, Hystricognathi). Cell suspensions were obtained by peripheral blood culture, besides bone marrow and spleen cells, from D. prymnolopha and D. leporina. The diploid number was 64/65 for all samples. The karyotypes showed similarity, and chromosomal polymorphism was not detected by Giemsa conventional staining and G banding. The constitutive heterochromatin distribution at the pericentromeric region of all the chromosomes was similar in all species. D. prymnolopha, D. leporina and Dasyprocta sp. presented variation in the heterochromatical block size at one of the homologues of the A18 pair. D. fuliginosa presented the heterochromatin uniformly distributed in all chromosomes. There was not variation in the NORs pattern in the species studied.

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Geographical variation of heterochromatin in <i>Ctenomys flamarion</i><i>i</i> (Rodentia-Octodontidae) and its cytogenetic relationships with other species of the genus

Cited by 47 publications

References 8 publications

G-banding patterns of the genusCtenomysfrom Uruguay (Rodentia Ctenomydae): high karyotype variation but chromosome arm conservation

G-banding patterns of the genusCtenomysfrom Uruguay (Rodentia Ctenomydae): high karyotype variation but chromosome arm conservation

Possible Heterochromatin Horizontal Spread through Non-Homologous Chromosome Associations in Pachytene Chromocenters of <i>Ctenomys </i>Rodents

Karyotypic analysis in species of the genus Dasyprocta (Rodentia: Dasyproctidae) found in Brazilian Amazon

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