Dissection of a Y-autosome translocation in Cryptomys hottentotus (Rodentia, Bathyergidae) and implications for the evolution of a meiotic sex chromosome chain

Deuve, Jane Lynda; Bennett, Nigel C.; Ruiz‐Herrera, Aurora; Waters, Paul D.; Britton‐Davidian, Janice; Robinson, Terence J.

doi:10.1007/s00412-007-0140-6

Cited by 11 publications

(9 citation statements)

References 31 publications

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“…To account for the fixation of these chromosomal rearrangements, several authors [for a review, see Dobigny et al, 2004] have proposed that accumulation of heterochromatin between the sex and autosomal segments may serve to insulate the 2 chromosomal arms, thus reducing the disruptive effects of these types of rearrangements. Support for this hypothesis is found in almost all mammal species known to possess sex-autosome fusions, in which a large block of heterochromatin is identified between the autosome and the X chromosome segments [e.g., Ratomponirina et al, 1986;Jaafar et al, 1993;Yang et al, 1997;Metcalfe et al, 1998;Rodrigues Noronha et al, 2001;Dobigny et al, 2004;Deuve et al, 2008]. However, concerning the African pygmy mice, while results for M .…”

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confidence: 80%

“…This suggests that inherent genomic traits allowing a higher rate of occurrence and/or fixation of this rearrangement may be present within the Nannomys . In other mammal species with sex-autosome fusions, a large block of heterochromatin is almost systematically present between the autosome and the X chromosome components [e.g., Ratomponirina et al, 1986;Jaafar et al, 1993;Yang et al, 1997;Metcalfe et al, 1998;Rodrigues Noronha et al, 2001;Dobigny et al, 2004;Deuve et al, 2008]. It has thus been proposed that such a heterochromatic block has been selected to functionally isolate the original X and the translocated autosome.…”

Section: Role Of Its As a Buffer Between Autosomal And Sex Chromosomementioning

confidence: 99%

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Extensive Amplification of Telomeric Repeats in the Karyotypically Highly Diverse African Pygmy Mice

Colomina¹,

Catalan²,

Britton‐Davidian³

et al. 2017

Cytogenet Genome Res

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Telomeres are ribonucleoprotein structures protecting the physical ends of eukaryotic chromosomes. However, telomeric sequences can also occur at non-terminal regions of chromosomes, forming the so-called interstitial telomeric sequences (ITSs). Some ITSs are considered as relics of past chromosomal rearrangements and as such provide important insights into karyotype evolution. By FISH, we explored the distribution of telomeric motifs in the genome of a complex of mammalian species that has long been recognized for its extraordinary karyotypic diversity: the African pygmy mice. This survey involved 5 species, representing 10 highly diverse karyotypes with or without autosomal and sex-autosome robertsonian (Rb) fusions. The study revealed that in species with an ancestral-like karyotype (i.e., no fusions; Mus mattheyi and M. indutus), only terminal telomeres were observed, whereas in species experiencing intense chromosomal evolution (e.g., M. minutoides, M. musculoides), a large amplification of telomeric repeats was also identified in the pericentromeric region of acrocentrics and most metacentrics. We concluded that (i) the mechanism of Rb fusion in the African pygmy mice is different than the one highlighted in the house mouse; (ii) the intensity of the ITS hybridization signal could be a signature of the age of formation of the Rb fusion; (iii) the large amplification of pericentromeric telomeric sequences in acrocentrics may mediate the formation of Rb fusions, and (iv) the ITSs on the sex-autosome fusion Rb(X.1) may participate to the insulation buffer between the sexual and autosomal arms to prevent X inactivation from spreading and silencing autosomal genes and allow the independent regulation of replication timing of both segments.

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mentioning

confidence: 80%

Section: Role Of Its As a Buffer Between Autosomal And Sex Chromosomementioning

confidence: 99%

Extensive Amplification of Telomeric Repeats in the Karyotypically Highly Diverse African Pygmy Mice

Colomina¹,

Catalan²,

Britton‐Davidian³

et al. 2017

Cytogenet Genome Res

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“…Mole-rat tissue samples were collected as part of a previous study carried out by Deuve et al [88]–[90] with full ethics approval by the University of Stellenbosch, Ethics Clearance Certificate # 2006B01006.…”

Section: Methodsmentioning

confidence: 99%

Genetic Signatures for Enhanced Olfaction in the African Mole-Rats

2014

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The Olfactory Receptor (OR) superfamily, the largest in the vertebrate genome, is responsible for vertebrate olfaction and is traditionally subdivided into 17 OR families. Recent studies characterising whole-OR subgenomes revealed a ‘birth and death’ model of evolution for a range of species, however little is known about fine-scale evolutionary dynamics within single-OR families. This study reports the first assessment of fine-scale OR evolution and variation in African mole-rats (Bathyergidae), a family of subterranean rodents endemic to sub-Saharan Africa. Because of the selective pressures of life underground, enhanced olfaction is proposed to be fundamental to the evolutionary success of the Bathyergidae, resulting in a highly diversified OR gene-repertoire. Using a PCR-sequencing approach, we analysed variation in the OR7 family across 14 extant bathyergid species, which revealed enhanced levels of functional polymorphisms concentrated across the receptors’ ligand-binding region. We propose that mole-rats are able to recognise a broad range of odorants and that this diversity is reflected throughout their OR7 gene repertoire. Using both classic tests and tree-based methods to test for signals of selection, we investigate evolutionary forces across the mole-rat OR7 gene tree. Four well-supported clades emerged in the OR phylogeny, with varying signals of selection; from neutrality to positive and purifying selection. Bathyergid life-history traits and environmental niche-specialisation are explored as possible drivers of adaptive OR evolution, emerging as non-exclusive contributors to the positive selection observed at OR7 genes. Our results reveal unexpected complexity of evolutionary mechanisms acting within a single OR family, providing insightful perspectives into OR evolutionary dynamics.

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“…In mammals, meiotic trivalents following sex-autosome translocations are not that uncommon (e.g., Fredga 1970;Ratomponirina et al 1986;Dobigny et al 2004;Deuve et al 2008;Veyrunes et al 2014;Rahn et al 2016;Vozdova et al 2016), suggesting common mechanisms to face the meiotic hurdles. In contrast, sex chromosome multivalents derived from four or more chromosomes are extremely rare, since they greatly interfere with meiotic progression and often cause infertility (Gruetzner et al 2006).…”

Section: Discussionmentioning

confidence: 99%

Sex chromosome quadrivalents in oocytes of the African pygmy mouse Mus minutoides that harbors non-conventional sex chromosomes

2019

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Eutherian mammals have an extremely conserved sex-determining system controlled by highly differentiated sex chromosomes. Females are XX and males XY, and any deviation generally leads to infertility, mainly due to meiosis disruption. The African pygmy mouse (Mus minutoides) presents an atypical sex determination system with three sex chromosomes: the classical X and Y chromosomes and a feminizing X chromosome variant, called X*. Thus, three types of females coexist (XX, XX*, and X*Y) that all show normal fertility. Moreover, the three chromosomes (X and Y on one side and X* on the other side) are fused to different autosomes, which results in the inclusion of the sex chromosomes in a quadrivalent in XX* and X*Y females at meiotic prophase. Here, we characterized the configurations adopted by these sex chromosome quadrivalents during meiotic prophase. The XX* quadrivalent displayed a closed structure in which all homologous chromosome arms were fully synapsed and with sufficient crossovers to ensure the reductional segregation of all chromosomes at the first meiotic division. Conversely, the X*Yquadrivalents adopted either a closed configuration with non-homologous synapsis of the X* and Y chromosomes or an open chain configuration in which X* and Y remained asynapsed and possibly transcriptionally silenced. Moreover, the number of crossovers was insufficient to ensure chromosome segregation in a significant fraction of nuclei. Together, these findings raise questions about the mechanisms allowing X*Y females to have a level of fertility as good as that of XX and XX* females, if not higher.

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Dissection of a Y-autosome translocation in Cryptomys hottentotus (Rodentia, Bathyergidae) and implications for the evolution of a meiotic sex chromosome chain

Cited by 11 publications

References 31 publications

Extensive Amplification of Telomeric Repeats in the Karyotypically Highly Diverse African Pygmy Mice

Extensive Amplification of Telomeric Repeats in the Karyotypically Highly Diverse African Pygmy Mice

Genetic Signatures for Enhanced Olfaction in the African Mole-Rats

Sex chromosome quadrivalents in oocytes of the African pygmy mouse Mus minutoides that harbors non-conventional sex chromosomes

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