The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Mitsuru Sakaizumi - One of the best experts on this subject based on the ideXlab platform.
-
Inter- and Intraspecific Variation in Sex Hormone-Induced Sex-Reversal in Medaka, Oryzias latipes and Oryzias sakaizumii
Zoological Science, 2019Co-Authors: Taijun Myosho, Satoshi Hamaguchi, Tadashi Sato, Hiroka Nishiyama, Akiho Watanabe, Jun Yamamoto, Tetsuro Okamura, Yuta Onishi, Rei Fujimaki, Mitsuru SakaizumiAbstract:We compared sex-reversal ratios induced by 17α-methyltestosterone (MT) and 17β-estradiol (E2) exposure in two inbred medaka strains: Hd-rR derived from Oryzias latipes and HNI-II from O. sakaizumii. All MT exposures (0.2–25 ng mL–1) induced complete XX sex-reversal in HNI-II. Although MT exposure at 0.2 ng mL–1 induced XX sex-reversal at > 95% in Hd-rR, other concentrations tested caused XX sex-reversal at lower frequencies ( 10 ng mL–1, and in all fish feminization occurred 500 ng mL–1. In HNI-II, E2 induced XY sex-reversal at 50 and 250 ng mL–1, but only at rates below 20%. To clarify whether the strain differences in sex hormone-induced sex-reversal are characteristic of each species, we examined the effects of MT and E2 exposure on sex differentiation in five and two additional strains or wild stocks/populations of O. latipes and O. sakaizumii, respectively. MT exposure induced low XX and high XY sex-reversal rates in O. latipes, except in the Shizuoka population, but the trend was reversed in O. sakaizumii. Furthermore, E2-induced XY sex-reversal rates varied intraspecifically in O. latipes. Our results demonstrated that sensitivity to MT and E2 varied within O. latipes species. To evaluate the ecological impacts of environmental chemicals using medaka, it is important to define not only the species, but the strains, stocks, and populations to obtain accurate results.
-
Evolution of the sex-determining gene in the teleostean genus Oryzias.
General and Comparative Endocrinology, 2015Co-Authors: Masaru Matsuda, Mitsuru SakaizumiAbstract:In the genetic sex determination of vertebrates, the gonadal sex depends on the combination of sex chromosomes that a zygote possesses. Despite the discovery of the sex-determining gene (SRY/Sry) in mammals in 1990s, the sex-determining gene in non-mammalian vertebrates remained an enigma for over a decade. In most mammals, the male-inducing master sex-determining gene is located on the Y chromosome and is therefore absent from XX females. A second sex-determining gene, Dmy, was described in the Oryzias latipes in 2002 and has a DNA-binding motif that is different from the motif in the mammalian sex-determining gene SRY or Sry. Dmy is also located on the Y chromosome and is therefore absent in XX females. Seven other sex-determining genes, including candidate genes, are now known in birds, a frog species, and 5 fish species. These findings over the past twenty years have increased our knowledge of sex-determining genes and sex chromosomes among vertebrates. Here, we review recent advances in our understanding of sex-determining genes and genetic sex determination systems in fish, especially those of the Oryzias species, which are described in detail. The facts suggest some patterns of how new sex-determining genes emerged and evolved. We believe that these facts are common not only in Oryzias but also in other fish species. This knowledge will help to elucidate the conserved mechanisms from which various sex-determining mechanisms have evolved.
-
The origin of the large metacentric chromosome pair in Chinese medaka ( Oryzias sinensis )
Ichthyological Research, 2012Co-Authors: Taijun Myosho, Yusuke Takehana, Satoshi Hamaguchi, Tadashi Sato, Mitsuru SakaizumiAbstract:Japanese medakas (Oryzias latipes and Oryzias sakaizumii) have 48 chromosomes, while the Chinese medaka (Oryzias sinensis) has 46 chromosomes, including one pair of large metacentric chromosomes. Linkage analysis using O. sakaizumii and O. sinensis strains showed that DNA markers in linkage groups (LG) 11 and 13 were tightly linked. Centromeric genomic clones of LG 11 and 13 derived from an O. latipes strain hybridized across the centromeres of the pair of large metacentric chromosomes in an O. sinensis strain. These results demonstrate that the large metacentric chromosome pair was derived from two pairs of acrocentric chromosomes (LG 11 and 13) through Robertsonian fusion.
-
A sex-determining region on the Y chromosome controls the sex-reversal ratio in interspecific hybrids between Oryzias curvinotus females and Oryzias latipes males
Heredity, 2009Co-Authors: Mariko Kato, Yusuke Takehana, Mitsuru Sakaizumi, Satoshi HamaguchiAbstract:A sex-determining region on the Y chromosome controls the sex-reversal ratio in interspecific hybrids between Oryzias curvinotus females and Oryzias latipes males
-
Different origins of ZZ/ZW sex chromosomes in closely related medaka fishes, Oryzias javanicus and O. hubbsi
Chromosome Research, 2008Co-Authors: Yusuke Takehana, Satoshi Hamaguchi, Mitsuru SakaizumiAbstract: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.
Yoshitaka Nagahama - One of the best experts on this subject based on the ideXlab platform.
-
dmy initiates masculinity by altering gsdf sox9a2 rspo1 expression in medaka Oryzias latipes
Scientific Reports, 2016Co-Authors: Tapas Chakraborty, Linyan Zhou, Aparna Chaudhari, Taisen Iguchi, Yoshitaka NagahamaAbstract:Dmy initiates masculinity by altering Gsdf / Sox9a2 / Rspo1 expression in medaka ( Oryzias latipes )
-
Dmy initiates masculinity by altering Gsdf/Sox9a2/Rspo1 expression in medaka (Oryzias latipes)
Scientific Reports, 2016Co-Authors: Tapas Chakraborty, Linyan Zhou, Aparna Chaudhari, Taisen Iguchi, Yoshitaka NagahamaAbstract:Dmy initiates masculinity by altering Gsdf / Sox9a2 / Rspo1 expression in medaka ( Oryzias latipes )
-
Oryzias curvinotus has dmy a gene that is required for male development in the medaka o latipes
Zoological Science, 2003Co-Authors: Masaru Matsuda, Yoshitaka Nagahama, Satoshi Hamaguchi, Tadashi Sato, Yota Toyazaki, Mitsuru SakaizumiAbstract:DMY is a Y-specific DM-domain gene required for male development and appears to be the sex-determining gene in the teleost fish medaka, Oryzias latipes. Although the genomic region containing DMY appears to have originated through duplication of the DMRT1 region, it is unknown when the duplication occurred. Here we show that O. curvinotus also has the DMY gene on the Y chromosome, which is homologous to the Y chromosome of medaka, and that DMY is expressed in XY embryos. A phylogenetic tree based on the amino acid sequence including the DM-domain shows that DMY was derived from DMRT1 immediately before speciation of O. latipes and O. curvinotus.
-
construction of a bac library derived from the inbred hd rr strain of the teleost fish Oryzias latipes
Genes & Genetic Systems, 2001Co-Authors: Masaru Matsuda, Yoshitaka Nagahama, Satoshi Hamaguchi, Mitsuru Sakaizumi, Norihisa Kawato, Shuichi Asakawa, Nobuyoshi Shimizu, Hiroshi HoriAbstract:A large insert genomic bacterial artificial chromosome (BAC) library was constructed from the inbred Hd-rR strain of the medaka, Oryzias latipes. Approximately 92, 000 clones were gridded on high-density replica filters. Insert analysis of randomly selected clones indicated a mean insert size of 210 kb and predicted a 24 times coverage of the medaka genome. The library was hybridized with a single locus DNA fragment, and the resulting positive clones were characterized and shown to be compatible with a 24-fold redundant library. This first large insert genomic library of the medaka should increase the speed of genomic analyses for this fish species.
Yusuke Takehana - One of the best experts on this subject based on the ideXlab platform.
-
genome sequence of the euryhaline javafish medaka Oryzias javanicus a small aquarium fish model for studies on adaptation to salinity
G3: Genes Genomes Genetics, 2020Co-Authors: Yusuke Takehana, Margot Zahm, Cedric Cabau, Christophe Klopp, Celine Roques, Olivier Bouchez, Cecile Donnadieu, Celia Barrachina, Laurent Journot, Mari KawaguchiAbstract:The genus Oryzias consists of 35 medaka-fish species each exhibiting various ecological, morphological and physiological peculiarities and adaptations. Beyond of being a comprehensive phylogenetic group for studying intra-genus evolution of several traits like sex determination, behavior, morphology or adaptation through comparative genomic approaches, all medaka species share many advantages of experimental model organisms including small size and short generation time, transparent embryos and genome editing tools for reverse and forward genetic studies. The Java medaka, Oryzias javanicus, is one of the two species of medaka perfectly adapted for living in brackish/sea-waters. Being an important component of the mangrove ecosystem, O. javanicus is also used as a valuable marine test-fish for ecotoxicology studies. Here, we sequenced and assembled the whole genome of O. javanicus, and anticipate this resource will be catalytic for a wide range of comparative genomic, phylogenetic and functional studies. Complementary sequencing approaches including long-read technology and data integration with a genetic map allowed the final assembly of 908 Mbp of the O. javanicus genome. Further analyses estimate that the O. javanicus genome contains 33% of repeat sequences and has a heterozygosity of 0.96%. The achieved draft assembly contains 525 scaffolds with a total length of 809.7 Mbp, a N50 of 6,3 Mbp and a L50 of 37 scaffolds. We identified 21454 predicted transcripts for a total transcriptome size of 57, 146, 583 bps. We provide here a high-quality chromosome scale draft genome assembly of the euryhaline Javafish medaka (321 scaffolds anchored on 24 chromosomes (representing 97.7% of the total bases)), and give emphasis on the evolutionary adaptation to salinity.
-
genome sequence of the euryhaline javafish medaka Oryzias javanicus a small aquarium fish model for studies on adaptation to salinity
bioRxiv, 2019Co-Authors: Yusuke Takehana, Margot Zahm, Cedric Cabau, Christophe Klopp, Celine Roques, Olivier Bouchez, Cecile Donnadieu, Celia Barrachina, Laurent Journot, Mari KawaguchiAbstract:ABSTRACT Background The genus Oryzias is constituted of 35 medaka-fish species each exhibiting various ecological, morphological and physiological peculiarities and adaptations. Beyond of being a comprehensive phylogenetic group for studying intra-genus evolution of several traits like sex determination, behaviour, morphology or adaptation through comparative genomic approaches, all medaka species share many advantages of experimental model organisms including small size and short generation time, transparent embryos and genome editing tools for reverse and forward genetic studies. The Java medaka, Oryzias javanicus, is one of the two species of medaka perfectly adapted for living in brackish/sea-waters. Being an important component of the mangrove ecosystem, O. javanicus is also used as a valuable marine test-fish for ecotoxicology studies. Here, we sequenced and assembled the whole genome of O. javanicus, and anticipate this resource will be catalytic for a wide range of comparative genomic, phylogenetic and functional studies. Findings Complementary sequencing approaches including long-read technology and data integration with a genetic map allowed the final assembly of 908 Mbp of the O. javanicus genome. Further analyses estimate that the O. javanicus genome contains 33% of repeat sequences and has a heterozygosity of 0.96%. The achieved draft assembly contains 525 scaffolds with a total length of 809.7 Mbp, a N50 of 6.3 Mbp and a L50 of 37 scaffolds. We identified 21454 expressed transcripts for a total transcriptome size of 57, 146, 583 bps. Conclusions We provide here a high-quality draft genome assembly of the euryhaline Javafish medaka, and give emphasis on the evolutionary adaptation to salinity.
-
co option of sox3 as the male determining factor on the y chromosome in the fish Oryzias dancena
Nature Communications, 2014Co-Authors: Yusuke Takehana, Taijun Myosho, Masaru Matsuda, Maximiliano L Suster, Koichi Kawakami, Tadasu Shini, Yuji Kohara, Yoko KurokiAbstract:Sex chromosomes harbour a primary sex-determining signal that triggers sexual development of the organism. However, diverse sex chromosome systems have been evolved in vertebrates. Here we use positional cloning to identify the sex-determining locus of a medaka-related fish, Oryzias dancena, and find that the locus on the Y chromosome contains a cis-regulatory element that upregulates neighbouring Sox3 expression in developing gonad. Sex-reversed phenotypes in Sox3Y transgenic fish, and Sox3Y loss-of-function mutants all point to its critical role in sex determination. Furthermore, we demonstrate that Sox3 initiates testicular differentiation by upregulating expression of downstream Gsdf, which is highly conserved in fish sex differentiation pathways. Our results not only provide strong evidence for the independent recruitment of Sox3 to male determination in distantly related vertebrates, but also provide direct evidence that a novel sex determination pathway has evolved through co-option of a transcriptional regulator potentially interacted with a conserved downstream component. Sex chromosomes harbour specific sequences that determine the sexual development of the organism; yet these sequences remain unknown for many species. Here, Takehana et al. show that, similarly to mammals, Sox3 on the Y chromosome is the male-determining factor in the medaka-related fish Oryzias dancena.
-
The origin of the large metacentric chromosome pair in Chinese medaka ( Oryzias sinensis )
Ichthyological Research, 2012Co-Authors: Taijun Myosho, Yusuke Takehana, Satoshi Hamaguchi, Tadashi Sato, Mitsuru SakaizumiAbstract:Japanese medakas (Oryzias latipes and Oryzias sakaizumii) have 48 chromosomes, while the Chinese medaka (Oryzias sinensis) has 46 chromosomes, including one pair of large metacentric chromosomes. Linkage analysis using O. sakaizumii and O. sinensis strains showed that DNA markers in linkage groups (LG) 11 and 13 were tightly linked. Centromeric genomic clones of LG 11 and 13 derived from an O. latipes strain hybridized across the centromeres of the pair of large metacentric chromosomes in an O. sinensis strain. These results demonstrate that the large metacentric chromosome pair was derived from two pairs of acrocentric chromosomes (LG 11 and 13) through Robertsonian fusion.
-
A sex-determining region on the Y chromosome controls the sex-reversal ratio in interspecific hybrids between Oryzias curvinotus females and Oryzias latipes males
Heredity, 2009Co-Authors: Mariko Kato, Yusuke Takehana, Mitsuru Sakaizumi, Satoshi HamaguchiAbstract:A sex-determining region on the Y chromosome controls the sex-reversal ratio in interspecific hybrids between Oryzias curvinotus females and Oryzias latipes males
Satoshi Hamaguchi - One of the best experts on this subject based on the ideXlab platform.
-
Inter- and Intraspecific Variation in Sex Hormone-Induced Sex-Reversal in Medaka, Oryzias latipes and Oryzias sakaizumii
Zoological Science, 2019Co-Authors: Taijun Myosho, Satoshi Hamaguchi, Tadashi Sato, Hiroka Nishiyama, Akiho Watanabe, Jun Yamamoto, Tetsuro Okamura, Yuta Onishi, Rei Fujimaki, Mitsuru SakaizumiAbstract:We compared sex-reversal ratios induced by 17α-methyltestosterone (MT) and 17β-estradiol (E2) exposure in two inbred medaka strains: Hd-rR derived from Oryzias latipes and HNI-II from O. sakaizumii. All MT exposures (0.2–25 ng mL–1) induced complete XX sex-reversal in HNI-II. Although MT exposure at 0.2 ng mL–1 induced XX sex-reversal at > 95% in Hd-rR, other concentrations tested caused XX sex-reversal at lower frequencies ( 10 ng mL–1, and in all fish feminization occurred 500 ng mL–1. In HNI-II, E2 induced XY sex-reversal at 50 and 250 ng mL–1, but only at rates below 20%. To clarify whether the strain differences in sex hormone-induced sex-reversal are characteristic of each species, we examined the effects of MT and E2 exposure on sex differentiation in five and two additional strains or wild stocks/populations of O. latipes and O. sakaizumii, respectively. MT exposure induced low XX and high XY sex-reversal rates in O. latipes, except in the Shizuoka population, but the trend was reversed in O. sakaizumii. Furthermore, E2-induced XY sex-reversal rates varied intraspecifically in O. latipes. Our results demonstrated that sensitivity to MT and E2 varied within O. latipes species. To evaluate the ecological impacts of environmental chemicals using medaka, it is important to define not only the species, but the strains, stocks, and populations to obtain accurate results.
-
The origin of the large metacentric chromosome pair in Chinese medaka ( Oryzias sinensis )
Ichthyological Research, 2012Co-Authors: Taijun Myosho, Yusuke Takehana, Satoshi Hamaguchi, Tadashi Sato, Mitsuru SakaizumiAbstract:Japanese medakas (Oryzias latipes and Oryzias sakaizumii) have 48 chromosomes, while the Chinese medaka (Oryzias sinensis) has 46 chromosomes, including one pair of large metacentric chromosomes. Linkage analysis using O. sakaizumii and O. sinensis strains showed that DNA markers in linkage groups (LG) 11 and 13 were tightly linked. Centromeric genomic clones of LG 11 and 13 derived from an O. latipes strain hybridized across the centromeres of the pair of large metacentric chromosomes in an O. sinensis strain. These results demonstrate that the large metacentric chromosome pair was derived from two pairs of acrocentric chromosomes (LG 11 and 13) through Robertsonian fusion.
-
A sex-determining region on the Y chromosome controls the sex-reversal ratio in interspecific hybrids between Oryzias curvinotus females and Oryzias latipes males
Heredity, 2009Co-Authors: Mariko Kato, Yusuke Takehana, Mitsuru Sakaizumi, Satoshi HamaguchiAbstract:A sex-determining region on the Y chromosome controls the sex-reversal ratio in interspecific hybrids between Oryzias curvinotus females and Oryzias latipes males
-
Different origins of ZZ/ZW sex chromosomes in closely related medaka fishes, Oryzias javanicus and O. hubbsi
Chromosome Research, 2008Co-Authors: Yusuke Takehana, Satoshi Hamaguchi, Mitsuru SakaizumiAbstract: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.
-
Identification of the sex-determining locus in the Thai medaka, Oryzias minutillus
Cytogenetic and Genome Research, 2008Co-Authors: T Nagai, Yusuke Takehana, Satoshi Hamaguchi, Mitsuru SakaizumiAbstract:A sex-determining gene, DMY, which is comparable to the SRY gene in mammals, has been identified in the medaka, Oryzias latipes. Although Oryzias curvinotus, a closely related species to O. latipes also has DMY, this gene has not been found in other Oryzias fishes. It has recently been demonstrated that the sex chromosomes of Oryzias dancena and Oryzias hubbsi differ from those of O. latipes and these species have XX/XY and ZZ/ZW systems, respectively. This may suggest that Oryzias species have evolved different sex-determining genes on different sex chromosomes. In the present study, we investigated the sex determination mechanism in Oryzias minutillus, which is closely related to O. dancena and O. hubbsi. Linkage analysis using 14 isolated sex-linked DNA markers showed that this species has an XX/XY sex determination system. These sex-linked markers were located on linkage group 8 of O. latipes, suggesting that the sex chromosomes of O. minutillus are homologous to the autosomes of other Oryzias species. Furthermore, fluorescence in situ hybridization using a tightly sex-linked marker demonstrated that the XY sex chromosomes of O. minutillus and O. dancena were not homologous. These findings provide additional evidence for independent origins of sex chromosomes and sex-determining genes in these closely related species.
Linyan Zhou - One of the best experts on this subject based on the ideXlab platform.
-
dmy initiates masculinity by altering gsdf sox9a2 rspo1 expression in medaka Oryzias latipes
Scientific Reports, 2016Co-Authors: Tapas Chakraborty, Linyan Zhou, Aparna Chaudhari, Taisen Iguchi, Yoshitaka NagahamaAbstract:Dmy initiates masculinity by altering Gsdf / Sox9a2 / Rspo1 expression in medaka ( Oryzias latipes )
-
Dmy initiates masculinity by altering Gsdf/Sox9a2/Rspo1 expression in medaka (Oryzias latipes)
Scientific Reports, 2016Co-Authors: Tapas Chakraborty, Linyan Zhou, Aparna Chaudhari, Taisen Iguchi, Yoshitaka NagahamaAbstract:Dmy initiates masculinity by altering Gsdf / Sox9a2 / Rspo1 expression in medaka ( Oryzias latipes )
