Identification of the sex-determining locus in the Thai medaka, &lt;i&gt;Oryzias minutillus&lt;/i&gt;

Nagai, Takahiro; Takehana, Yusuke; Hamaguchi, Satoshi; Sakaizumi, Mitsuru

doi:10.1159/000125839

Cited by 23 publications

(16 citation statements)

References 65 publications

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“…In teleosts, the sex-determining gene dmy , discovered in medaka Oryzias latipes, exists in only 2 species [Matsuda et al, 2002[Matsuda et al, , 2003. Furthermore, recent reports suggest that in other medaka, such as Oryzias dancena, Oryzias luzonensis, and Oryzias minutillus, a gene other than dmy is a candidate for sex determination Tanaka et al, 2007;Nagai et al, 2008]. Nonetheless, morphological differentiation and development of the gonads in all vertebrates appear to have been conserved throughout evolution.…”

Section: Resultsmentioning

confidence: 99%

Molecular Aspects of Gonadal Differentiation in a Teleost Fish, the Nile Tilapia

Kobayashi

Nagahama²

2009

Sex Dev

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In contrast to many developmental processes, sex-determining mechanisms show no clear evolutionary conservation among phyla. However, recent studies indicate that some downstream products of sex determination genes are functionally similar in diverse species. To date, numerous conserved genes involving gonadal sex differentiation have been examined in the teleost fish Nile tilapia (Oreochromis niloticus). Morphogenesis during gonadal differentiation is also conserved, as is evident in the differentiation and development of parenchyma/medullary cells (testis cord) and follicles. Therefore, it is important to understand the mechanisms of gonadal sex differentiation from the perspective of the relationship between conserved gene expression cascades and morphogenesis during gonadal sex differentiation. This article reviews the expression profiles of male- and female-related genes involved in histogenesis during sex differentiation in tilapia and discusses gene function in gonadal sex differentiation, especially the role of endogenous estrogens for ovarian differentiation.

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Section: Resultsmentioning

confidence: 99%

Molecular Aspects of Gonadal Differentiation in a Teleost Fish, the Nile Tilapia

Kobayashi

Nagahama²

2009

Sex Dev

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“…These findings and the sister group relationship between O. javanicus and O. hubbsi suggest that at least one transition between the alternative sex determination systems (XX/XY and ZZ/ZW) has occurred within the javanicus species group lineage. Sex chromosomes and/or sex linkage groups have previously been identified in the above-mentioned seven Oryzias species; namely, O. mekongensis (unpublished data), O. latipes (Matsuda et al 2002), O. curvinotus (Matsuda et al 2003), O. luzonensis (Tanaka et al 2007), O. minutillus (Nagai et al 2008), O. dancena (Takehana et al 2007a) and O. hubbsi (Takehana et al 2007b). Except for O. latipes and O. curvinotus, the sex chromosomes differ from species to species (see Figure 6).…”

Section: Identification Of Sex Chromosomes By Fish Analysismentioning

confidence: 88%

Different origins of ZZ/ZW sex chromosomes in closely related medaka fishes, Oryzias javanicus and O. hubbsi

2008

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Although the sex-determining gene DMY has been identified on the Y chromosome in the medaka, Oryzias latipes, this gene is absent in most Oryzias species. Recent comparative studies have demonstrated that, in the javanicus species group, Oryzias dancena and Oryzias minutillus have an XX/XY sex determination system, while Oryzias hubbsi has a ZZ/ZW system. Furthermore, sex chromosomes were not homologous in these species. Here, we investigated the sex determination mechanism in Oryzias javanicus, another species in the javanicus group. Linkage analysis of isolated sex-linked DNA markers showed that this species has a ZZ/ZW sex determination system. The sex-linkage map showed a conserved synteny to the linkage group 16 of O. latipes, suggesting that the sex chromosomes in O. javanicus are not homologous to those in any other Oryzias species. Fluorescence in-situ hybridization analysis confirmed that the ZW sex chromosomes of O. javanicus and O. hubbsi are not homologous, and showed that O. javanicus has the morphologically heteromorphic sex chromosomes, in which the W chromosome has 4,6-diamino-2-phenylindole-positive heterochromatin at the centromere. These findings suggest the repeated evolution of new sex chromosomes from autosomes in Oryzias, probably through the emergence of new sex-determining genes.

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“…and O. javanicus (LG16) (Takehana et al 2007a(Takehana et al ,b, 2008Nagai et al 2008). Dmy has been detected only in O. latipes and O. curvinotus.…”

Section: Gsdf Y -Specific Mutations Involved In High Expressionmentioning

confidence: 99%

Tracing the Emergence of a Novel Sex-Determining Gene in Medaka,Oryzias luzonensis

et al. 2012

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Three sex-determining (SD) genes, SRY (mammals), Dmy (medaka), and DM-W (Xenopus laevis), have been identified to date in vertebrates. However, how and why a new sex-determining gene appears remains unknown, as do the switching mechanisms of the master sex-determining gene. Here, we used positional cloning to search for the sex-determining gene in Oryzias luzonensis and found that Gsdf Y (gonadal soma derived growth factor on the Y chromosome) has replaced Dmy as the master sex-determining gene in this species. We found that Gsdf Y showed high expression specifically in males during sex differentiation. Furthermore, the presence of a genomic fragment that included Gsdf Y converts XX individuals into fertile XX males. Luciferase assays demonstrated that the upstream sequence of Gsdf Y contributes to the male-specific high expression. Gsdf is downstream of Dmy in the sex-determining cascade of O. latipes, suggesting that emergence of the Dmy-independent Gsdf allele led to the appearance of this novel sexdetermining gene in O. luzonensis. IN most vertebrates, sex is determined genetically. Mammals and birds with cytogenetically well-differentiated sex chromosomes have sex determination systems that differ between the taxonomic classes but not within them (Solari 1994). In mammals, for example, the sex-determining (SD) gene SRY/Sry on the Y chromosome has a universal role in sex determination (Gubbay et al. 1990;Sinclair et al. 1990;Koopman et al. 1991;Foster et al. 1992). By contrast, some fish groups, such as salmonids, sticklebacks, and Oryzias fishes, have sex chromosomes that differ among closely related species (Devlin and Nagahama 2002;Woram et al. 2003;Takehana et al. 2007a;Ross et al. 2009).A DM-domain gene, Dmy, was the first SD gene identified in a nonmammalian vertebrate, the fish medaka Oryzias latipes (Matsuda et al. 2002(Matsuda et al. , 2007. In this species, the term Y chromosome is employed to refer to a recombining chromosome that carries the male-determining gene Dmy, and X is used for the homologous chromosome; these are not a heteromorphic pair. This gene is conserved among all wild populations of O. latipes examined to date . The closely related species O. curvinotus also has Dmy on its Y chromosome, which is orthologous to the O. latipes Y chromosome (Matsuda et al. 2003). However, Dmy has not been detected in any other type of fish, including other Oryzias fishes (Kondo et al. 2003). Analysis of the Y-specific region of the O. latipes sex chromosome has demonstrated that Dmy arose from duplication of the autosomal Dmrt1 gene (Nanda et al. 2002;Kondo et al. 2006). This Dmrt1 duplication is estimated to have occurred within the last 10 million years in a common ancestor of O. latipes, O. curvinotus, and O. luzonensis. In O. luzonensis, however, no functional duplicated copy of Dmrt1 has been detected (Kondo et al. 2003) (Figure 5A).O. luzonensis possesses an XX-XY system, which is homologous to an autosomal linkage group (LG 12) and Uwa 1985). In the d-rR strain, the wild-type alle...

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Identification of the sex-determining locus in the Thai medaka, <i>Oryzias minutillus</i>

Cited by 23 publications

References 65 publications

Molecular Aspects of Gonadal Differentiation in a Teleost Fish, the Nile Tilapia

Molecular Aspects of Gonadal Differentiation in a Teleost Fish, the Nile Tilapia

Different origins of ZZ/ZW sex chromosomes in closely related medaka fishes, Oryzias javanicus and O. hubbsi

Tracing the Emergence of a Novel Sex-Determining Gene in Medaka,Oryzias luzonensis

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