Multiple copies of SRY on the large Y chromosome of the Okinawa spiny rat, Tokudaia muenninki

Murata, Chie; Yamada, Fumio; Kawauchi, Norihiro; Matsuda, Yoichi; Kuroiwa, Asato

doi:10.1007/s10577-010-9142-y

Cited by 32 publications

(64 citation statements)

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“…Neither T. osimensis nor T. tokunoshimensis has a Y chromosome and sex is determined with an XO/XO sex chromosome constitution in both species (Honda et al 1977(Honda et al , 1978Kobayashi et al 2007). Although the diploid chromosome number of T. muenninki is 44 with XX/XY sex chromosome constitution, both sex chromosomes are unusually large (Tsuchiya et al 1989;Murata et al 2010). The euchromatic regions of the X and Y chromosomes occupy 8% and 4% of the haploid genome, respectively, which suggests that an autosomal addition has occurred (Murata et al 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Although the diploid chromosome number of T. muenninki is 44 with XX/XY sex chromosome constitution, both sex chromosomes are unusually large (Tsuchiya et al 1989;Murata et al 2010). The euchromatic regions of the X and Y chromosomes occupy 8% and 4% of the haploid genome, respectively, which suggests that an autosomal addition has occurred (Murata et al 2010). On the basis of molecular phylogenetic analysis, T. muenninki was the first species in the genus to diverge, which suggests that the Y chromosome was lost in the common ancestor of T. osimensis and T. tokunoshimensis after this event (Murata et al 2010).…”

Section: Introductionmentioning

confidence: 99%

“…The euchromatic regions of the X and Y chromosomes occupy 8% and 4% of the haploid genome, respectively, which suggests that an autosomal addition has occurred (Murata et al 2010). On the basis of molecular phylogenetic analysis, T. muenninki was the first species in the genus to diverge, which suggests that the Y chromosome was lost in the common ancestor of T. osimensis and T. tokunoshimensis after this event (Murata et al 2010). Three stepwise events that led to the disappearance of the Y chromosome have been suggested; gene transpositions from the Y chromosome to autosomes, superseding Y-linked genes by new genes on the X chromosome or autosomes, and Y-to-X translocation containing Y-linked genes (Arakawa et al 2002;Kuroiwa et al 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Although T. muenninki possesses a Y chromosome, several aspects of sex determination in this species are unusual (Tsuchiya et al 1989;Murata et al 2010). Multiple copies of the SRY gene (>70) are found in T. muenninki, and these are distributed along the entire long arm of the Y chromosome (Murata et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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The Y chromosome of the Okinawa spiny rat, Tokudaia muenninki, was rescued through fusion with an autosome

Murata

Yamada

Kawauchi³

et al. 2011

Chromosome Res

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The genus Tokudaia comprises three species, two of which have lost their Y chromosome and have an XO/XO sex chromosome constitution. Although Tokudaia muenninki (Okinawa spiny rat) retains the Y chromosome, both sex chromosomes are unusually large. We conducted a molecular cytogenetic analysis to characterize the sex chromosomes of T. muenninki. Using crossspecies fluorescence in situ hybridization (Zoo-FISH), we found that both short arms of the T. muenninki sex chromosomes were painted by probes from mouse chromosomes 11 and 16. Comparative genomic hybridization analysis was unable to detect sex-specific regions in the sex chromosomes because both sex probes highlighted the large heterochromatic blocks on the Y chromosome as well as five autosomal pairs. We then performed comparative FISH mapping using 29 mouse complementary DNA (cDNA) clones of the 22 X-linked genes and the seven genes linked to mouse chromosome 11 (whose homologue had fused to the sex chromosomes), and FISH mapping using two T. muenninki cDNA clones of the Y-linked genes. This analysis revealed that the ancestral gene order on the long arm of the X chromosome and the centromeric region of the short arm of the Y chromosome were conserved. Whereas six of the mouse chromosome 11 genes were also mapped to Xp and Yp, in addition, one gene, CBX2, was also mapped to Xp, Yp, and chromosome 14 in T. muenninki. CBX2 is the candidate gene for the novel sex determination system in the two other species of Tokudaia, which lack a Y chromosome and SRY gene. Overall, these results indicated that the Y chromosome of T. muenninki avoided a loss event, which occurred in an ancestral lineage of T. osimensis and T. tokunoshimensis, through fusion with an autosome. Despite retaining the Y chromosome, sex determination Chromosome Res (2012) 20:111-125

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Y chromosome of the Okinawa spiny rat, Tokudaia muenninki, was rescued through fusion with an autosome

Murata

Yamada

Kawauchi³

et al. 2011

Chromosome Res

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“…Moreover, they provide good examples of the Y chromosome "clinging on to life." One spiny rat species T. muenninki, retains a Y containing sry but this does not bind DNA very well so, to compensate, has made 40-50 copies of itself in a "last gasp" (Murata et al 2010). An even more extreme view of our future is provided by some Drosophila species that are on their third Y chromosome.…”

Section: The Rebuttalsmentioning

confidence: 99%

Is the Y chromosome disappearing?—Both sides of the argument

Griffin

2011

Chromosome Res

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On August 31, 2011 at the 18th International Chromosome Conference in Manchester, Jenny Graves took on Jenn Hughes to debate the demise (or otherwise) of the mammalian Y chromosome. Sex chromosome evolution is an example of convergence; there are numerous examples of XY and ZW systems with varying degrees of differentiation and isolated examples of the Y disappearing in some lineages. It is agreed that the Y was once genetically identical to its partner and that the present-day human sex chromosomes retain only traces of their shared ancestry. The euchromatic portion of the male-specific region of the Y is~1/6 of the size of the X and has only~1/12 the number of genes. The big question however is whether this degradation will continue or whether it has reached a point of equilibrium. Jenny Graves argued that the Y chromosome is subject to higher rates of variation and inefficient selection and that Ys (and Ws) degrade inexorably. She argued that there is evidence that the Y in other mammals has undergone lineage-specific degradation and already disappeared in some rodent lineages. She also pointed out that there is practically nothing left of the original human Y and the added part of the human Y is degrading rapidly. Jenn Hughes on the other hand argued that the Y has not disappeared yet and it has been around for hundreds of millions of years. She stated that it has shown that it can outsmart genetic decay in the absence of "normal" recombination and that most of its genes on the human Y exhibit signs of purifying selection. She noted that it has added at least eight different genes, many of which have subsequently expanded in copy number, and that it has not lost any genes since the human and chimpanzee diverged~6 million years ago. The issue was put to the vote with an exact 50/50 split among the opinion of the audience; an interesting (though perhaps not entirely unexpected) skew however was noted in the sex ratio of those for and against the notion.

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Applying iPSCs for Preserving Endangered Species and Elucidating the Evolution of Mammalian Sex Determination

Honda

2018

BioEssays

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The endangered species Tokudaia osimensis has the unique chromosome constitution of 2n = 25, with an XO/XO sex chromosome configuration (2n = 25; XO). There is urgency to preserve this species and to elucidate the regulator(s) that can discriminate the males and females arising from the indistinguishable sex chromosome constitution. However, it is not realistic to examine this rare animal species by sacrificing individuals. Recently, true naïve induced pluripotent stem cells were successfully generated from a female T. osimensis, and the sexual plasticity of its germ cells was elucidated. This achievement constitutes the basis of an attractive research area, including embryonic fate determination, sex determination, and factor(s) that can replace the Y chromosome. In this essay, concrete strategies to conserve rare animal species and to reveal their specific characteristics using other compatible and abundant animals are proposed.

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Multiple copies of SRY on the large Y chromosome of the Okinawa spiny rat, Tokudaia muenninki

Cited by 32 publications

References 39 publications

The Y chromosome of the Okinawa spiny rat, Tokudaia muenninki, was rescued through fusion with an autosome

The Y chromosome of the Okinawa spiny rat, Tokudaia muenninki, was rescued through fusion with an autosome

Is the Y chromosome disappearing?—Both sides of the argument

Applying iPSCs for Preserving Endangered Species and Elucidating the Evolution of Mammalian Sex Determination

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