Additional copies of CBX2 in the genomes of males of mammals lacking SRY, the Amami spiny rat (Tokudaia osimensis) and the Tokunoshima spiny rat (Tokudaia tokunoshimensis)

  title={Additional copies of CBX2 in the genomes of males of mammals lacking SRY, the Amami spiny rat (Tokudaia osimensis) and the Tokunoshima spiny rat (Tokudaia tokunoshimensis)},
  author={Asato Kuroiwa and Sanae Handa and Chi E. Nishiyama and Eriko Chiba and Fumio Yamada and Shintaro Abe and Yoichi Matsuda},
  journal={Chromosome Research},
Tokudaia osimensis (the Amami spiny rat) and Tokudaia tokunoshimensis (the Tokunoshima spiny rat) have a sex chromosome composition of XO/XO, no Y chromosome. The mammalian sex-determining gene, SRY, is also absent in these species, which indicates that these spiny rats exhibit a novel sex-determining mechanism that is independent of SRY. To identify a candidate gene that controls this mechanism, the copy numbers and chromosomal locations of 10 genes with important functions in gonadal… 
Regulation of the Sox3 Gene in an X0/X0 Mammal without Sry, the Amami Spiny Rat, Tokudaia osimensis
It is concluded that the Sox3 gene has no function in sex determination in Sry-lacking Tokudaia species and the idea that the function of SOX3 as a transcription factor, as has been reported in mice and humans, is conserved in T. osimensis is supported.
Mutations in the Testis-Specific Enhancer of SOX9 in the SRY Independent Sex-Determining Mechanism in the Genus Tokudaia
The results indicate that the SRY dependent sex-determining mechanism was lost in a common ancestor of the genus Tokudaia caused by nucleotide substitutions in SRY and SF1 binding sites after emergence of a new sex-Determining gene.
Unique XCI evolution in Tokudaia: initial XCI of the neo-X chromosome in Tokudaia muenninki and function loss of XIST in Tokudaia osimensis
X chromosome inactivation (XCI) has evolved differently in two species of the genus Tokudaia, showing its loss of function in the XO/XO species and hybridization pattern correlated with LINE-1 accumulation in Xq but not in Xp.
Sox9 gene regulation and the loss of the XY/XX sex-determining mechanism in the mole vole Ellobius lutescens
This work proposes a model whereby Δ14 may have triggered up-regulation of Sox9 in XX gonads leading to destabilization of the XY/XX sex-determining mechanism in Ellobius, indicating that testicular Sox9 expression in E. lutescens might still be regulated via TESCO.
Molecular mechanism of male differentiation is conserved in the SRY-absent mammal, Tokudaia osimensis
The results indicate that TESCO enhancer activity was lost in Tokudaia osimensis, which lacks a Y chromosome and the SRY gene, and the activity of theSOX9 promoter was enhanced by ER71, indicating that ER71 may play an important role in the testis-specific expression of SOX9.
The Y chromosome of the Okinawa spiny rat, Tokudaia muenninki, was rescued through fusion with an autosome
Results indicated that the Y chromosome of T. muenninki avoided a loss event, which occurred in an ancestral lineage ofT.
Sexual dimorphism in brain transcriptomes of Amami spiny rats (Tokudaia osimensis): a rodent species where males lack the Y chromosome
This method successfully identified several genes and transcripts that showed expression differences in the brain of adult male and female Amami spiny rat, especially differential expression of transcripts encoding zinc finger proteins, in this unusual rodent species.
Genome-wide identification of CBX2 targets: insights in the human sex development network.
Large-scale mapping and analysis of in vivo target loci of the protein CBX2 in Sertoli-like NT-2D1 cells, using the DNA adenine methyltransferase identification technique, suggest that CBx2 role in the sex development cascade is to stimulate the male pathway and concurrently inhibit the female pathway.
Sex Chromosomes and Master Sex-Determining Genes in Turtles and Other Reptiles
This review describes the current knowledge of reptilian sex chromosomes at the cytogenetic and molecular level and a few putative master sex-determining (MSD) genes have been proposed, but none has been demonstrated yet.
CBX2 in DSD: The Quirky Kid on the Block.
An overview of Chromobox homolog 2 (CBX2), an important ortholog of the Polycomb group (PcG) proteins, that functions as both chromatin modifier and highly dynamic transactivator in mammals, is provided.


Multiple copies of SRY on the large Y chromosome of the Okinawa spiny rat, Tokudaia muenninki
Molecular phylogenetic trees with nucleotide sequences of cyt b, RAG1, and IRBP strongly supported that T. muenninki was the first to diverge from the Tokudaia ancestor, indicating that loss of the Y chromosome and SRY occurred in the common ancestor of the two XO/XO species after T.muenninki diverged.
X-chromosomal localization of mammalian Y-linked genes in two XO species of the Ryukyu spiny rat
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.
Exceptional minute sex-specific region in the X0 mammal, Ryukyu spiny rat
The result indicated that the sex-specific region, where the key to sex determination lies, is very minute in X0 species of Tokudaia, and the differences detected by CGH might be caused by the polymorphism on the copy numbers of repeated sequences in the heterochromatic and telomeric regions.
Male sex determination in the spiny rat Tokudaia osimensis (Rodentia: Muridae) is not Sry dependent
This species is thus the second rodent genus described so far as lacking the mammalian sex-determining factor Sry, since two species of voles in the genus Ellobius display the same unusual feature.
Sex determination without the Y Chromosome in two Japanese rodents Tokudaia osimensis osimensis and Tokudaia osimensis spp.
Comparison of physical characteristics, constituents of chromosomes, and sex-determination methods of these three Tokudaia country-rat populations suggests that each is endemic to each island and constitutes an independent species.
A duplicated copy of DMRT1 in the sex-determining region of the Y chromosome of the medaka, Oryzias latipes
  • I. Nanda, M. Kondo, M. Schartl
  • Biology
    Proceedings of the National Academy of Sciences of the United States of America
  • 2002
It is found that in the fish medaka the Y chromosome-specific region spans only about 280 kb and contains a duplicated copy of the autosomal DMRT1 gene, named D MRT1Y, which is the only functional gene in this chromosome segment and maps precisely to the male sex-determining locus.
DMY is a Y-specific DM-domain gene required for male development in the medaka fish
Rec recombinant breakpoint analysis is used to restrict the sex-determining region in medaka fish to a 530-kilobase stretch of the Y chromosome, and it is suggested that thesex-specific DMY is required for testicular development and is a prime candidate for the medaka sex-Determining gene.
Sry, Sox9 and mammalian sex determination.
This review focuses on what is known about the two genes and their likely modes of action, and draws together recent data relating to how they might interconnect with the network of gene activity implicated in testis determination in mammals.
Dax1 antagonizes Sry action in mammalian sex determination
Results show that DAX1 is largely, if not solely, responsible for dosage-sensitive sex reversal and provide a model for early events in mammalian sex determination, when precise levels and timing of gene expression are critical.
The mouse has a Polycomb-like chromobox gene.
It is proposed that M33 is a Pc-like chromobox gene, which encodes a predicted 519 amino acid protein and the roles of M33 and Pc in models of cellular memory are examined and implications of the memory models addressed.