AN UNUSUAL SEX CHROMOSOME CONSTITUTION FOUND IN THE AMAMI SPINOUS COUNTRY-RAT, &lt;i&gt;TOKUDAIA OSIMENSIS OSIMENSIS&lt;/i&gt;

Honda, Takeo; Suzuki, Hiroshi; Itoh, Minoru

doi:10.1266/jjg.52.247

Cited by 57 publications

(32 citation statements)

References 2 publications

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“…The intensive interpopulational differentiation of these two genes implies that the insular populations have been isolated in reproductive terms for a considerable time, probably millions of years, even though they had several opportunities for secondary contact during the Pleistocene ice age (Suzuki et al, 1999). Therefore, we can probably regard them as distinct species, based on morphological (Kaneko, 2001) and cytogenetic (Honda et al, 1977(Honda et al, , 1978Tsuchiya et al, 1989) evidence.…”

confidence: 99%

X-chromosomal localization of mammalian Y-linked genes in two XO species of the Ryukyu spiny rat

Arakawa¹,

Nishida‐Umehara

Matsuda

et al. 2002

Cytogenet Genome Res

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Ryukyu spiny rats (genus Tokudaia), which are endemic to the central part of the Nansei Shoto archipelago in Japan, have unique karyotypes with odd numbers of chromosomes and no cytologically recognizable Y chromosome. The chromosome numbers of Tokudaia osimensis from Amamioshima and of Tokudaia sp. from Tokunoshima are 2n = 25 and 2n = 45, respectively, with a putative single X chromosome. The mouse X probe hybridized to the unpaired X chromosome, except for the distal part of the short arm in a female specimen of T. osimensis and in one male and one female of Tokudaia sp. Fluorescence in situ hybridization with the Tspy (testis-specific protein, Y-encoded) gene from both male and female cells of Tokudaia sp. by PCR localized Tspy to the distal part of the long arm of the X chromosome. Another Y-related gene, Zfy, from Tokudaia sp. was also localized to the same region in both species. Although the Sry gene is absent in this species, the present results suggest that the Y-chromosome segment carrying functional Y-linked genes, such as Tspy and Zfy, is translocated onto the distal part of the long arm of the X chromosome.

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confidence: 99%

X-chromosomal localization of mammalian Y-linked genes in two XO species of the Ryukyu spiny rat

Arakawa¹,

Nishida‐Umehara

Matsuda

et al. 2002

Cytogenet Genome Res

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“…The diploid chromosome numbers of T. osimensis and T. tokunoshimensis are an odd number, 25 and 45, respectively. 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).…”

Section: Introductionmentioning

confidence: 99%

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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“…These male individuals obviously do not show any impairment in vitality from the lack of a Y chromosome. Among these exceptional species are the mole vole Ellobius lutescens (Matthey, 1953;Wolf, 1967, 1968;De La Maza and Sawyer, 1976) and the Japanese Amami spinous country-rat Tokudaia osimensis osimensis (Honda et al, 1977(Honda et al, , 1978Fredga, 1983). Recent studies on the presence and the involvement of Sry in male sex determination in the latter species showed that these animals do not have Sry in their genome (Soullier et al, 1998;Sutou et al, 2001).…”

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confidence: 99%

The sex determination in <i>Ellobius lutescens</i> remains bizarre

Just¹,

Baumstark²,

Hameister³

et al. 2002

Cytogenet Genome Res

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Mammalian sex determination and gonad differentiation are the result of a complex interaction of fine-tuned spatial and temporal gene expression with threshold levels of individual genes. The male pathway is initiated by SRY. Some exceptional mammals determine male sex without the SRY gene and even without a Y chromosome. Ellobius lutescens in this report is one example of this “weird” species. We provide key data on the genomic level that there are no coarse differences in the genomes of male and female animals by comparative genomic hybridization. On the gene level we studied the gene Nr5a1 for the orphan nuclear receptor, steroidogenic factor SF-1, a central constituent for gonad differentiation and adrenal gland development. The Ellobius lutescens Nr5a1 gene was mapped to the proximal short arm of chromosome 2 by fluorescence in situ hybridization. In addition, we provide evidence by linkage analysis in two E. lutescens pedigrees that Nr5a1 is not the key male sex-determining gene in Ellobius lutescens.

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AN UNUSUAL SEX CHROMOSOME CONSTITUTION FOUND IN THE AMAMI SPINOUS COUNTRY-RAT, <i>TOKUDAIA OSIMENSIS OSIMENSIS</i>

Cited by 57 publications

References 2 publications

X-chromosomal localization of mammalian Y-linked genes in two XO species of the Ryukyu spiny rat

X-chromosomal localization of mammalian Y-linked genes in two XO species of the Ryukyu spiny rat

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

The sex determination in <i>Ellobius lutescens</i> remains bizarre

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