The Experts below are selected from a list of 5106 Experts worldwide ranked by ideXlab platform
Hiroshi Hori - One of the best experts on this subject based on the ideXlab platform.
-
A Glance at the Past of Medaka Fish Biology
Medaka, 2011Co-Authors: Hiroshi HoriAbstract:The physiology, embryology, and genetics of Medaka have been extensively studied for the past 100 years. Here we review the past of Medaka Fish biology as genetic model systems for early development, pigmentation, sex determination, and human diseases.
-
The Tol1 element of Medaka Fish is transposed with only terminal regions and can deliver large DNA fragments into the chromosomes
Journal of human genetics, 2007Co-Authors: Akihiko Koga, Hiroshi Hori, Yuko Wakamatsu, Ichizo Higashide, Yoriko Kyono-hamaguchi, Satoshi HamaguchiAbstract:Tol1 is an active DNA-based transposable element residing in the genome of the Medaka Fish Oryzias latipes. This element belongs to the hAT transposable element family, of which complete copies have relatively long sequences. In addition, we found that Tol1 elements as long as 18 and 20 kb occur in the Medaka Fish genome. These facts suggest that Tol1 is suitable for carrying large DNA fragments as a gene transfer vector. Focusing on this, we conducted two kinds of manipulations of the element. The first was to eliminate internal regions dispensable for transposition. It was revealed that a Tol1 element consisting of 157-bp left- and 106-bp right-terminal regions could be transposed without a loss of transposition efficiency. Next, we prepared long Tol1 elements by incorporating unrelated DNA fragments into this short Tol1 clone and examined their transposition efficiencies. The transposition frequency decreased as the element size increased. The longest Tol1 element we examined measured 22.1 kb, and its transposition frequency was approximately one fifth that of a 2.1-kb element. However, this frequency was still significantly higher than that of a random integration of DNA into the chromosomes. The element size of 22.1 kb is the longest ever reported for DNA-based elements currently used for mammals. Thus, Tol1 is a superior gene-transfer vector with a large cargo capacity.
-
The Tol1 transposable element of the Medaka Fish moves in human and mouse cells.
Journal of human genetics, 2007Co-Authors: Akihiko Koga, Hiroshi Hori, Atsuko Shimada, Yoriko Kyono-hamaguchi, Toshiya Kuroki, Junko Kusumi, Satoshi HamaguchiAbstract:DNA-based transposable elements can be used as tools for gene engineering and gene therapy. A great advantage over RNA-mediated elements and retroviruses is the simplicity and safety of usage. The Tol1 element of the Medaka Fish Oryzias latipes has structural features of DNA-based elements. Although its excision has already been demonstrated, de novo insertion has not been observed, and a transposase has not been hitherto identified. We first cloned, through in silico search alignments and genomic library screenings, a 4.4-kb Tol1 copy carrying open reading frames and then identified, by mRNA analysis, a 2.9-kb transcript coding for 851 amino acids. The protein product of this transcript catalyzed transposition of a nonautonomous Tol1 copy in human and mouse culture cells. This identification of a fully functional Tol1 transposase could lead to the development of new tools for basic and translational molecular biology applications in mammals.
-
Expression and genomic organization of a Medaka Fish novel membrane form of guanylyl cyclase/orphan receptor.
Zoological Science, 2003Co-Authors: Sayaka Yamagami, Shan-hua Xu, Hiroshi Hori, Makiko Tsutsumi, Norio SuzukiAbstract:Abstract A novel membrane guanylyl cyclase (membrane GC), OlGC8, was identified in the Medaka Fish Oryzias latipes by the isolation of full-length cDNA (4958 bp) and genomic DNA (14.3 kbp) clones. Phylogenetic analysis indicated that OlGC8 does not belong in any known vertebrate membrane GC sub-family. OlGC8 consists of an extracellular domain (214 residues), a transmembrane segment (19 residues), and an intracellular protein kinase-like domain (284 residues) and a cyclase catalytic domain (228 residues), although the extracellular domain is about half the length (around 450 residues) of other known vertebrate membrane GCs. OlGC8 transiently expressed in COS-7 cells exhibited only basal guanylyl cyclase activity. None of the known ligands (rat ANP, BNP, CNP, and C-ANF) and various Medaka Fish tissue extracts, which activated OlGC1, OlGC2, and OlGC7 differentially, stimulated basal activity, suggesting that OlGC8 is an orphan receptor. The OlGC8 gene consists of 24 exons and exists as a single copy on the ...
-
The Medaka Fish Tol2 transposable element can undergo excision in human and mouse cells
Journal of Human Genetics, 2003Co-Authors: Akihiko Koga, Hiroshi Hori, Atsuo Iida, Megumi Kamiya, Ryoko Hayashi, Yuji Ishikawa, Akira TachibanaAbstract:Tol2 is an active DNA-based transposable element identified in the Medaka Fish, Oryzias latipes . Originating from a vertebrate and belonging to the hAT ( hobo / Activator / Tam3 ) transposable element family, featuring a wide distribution among organisms, Tol2 would be expected to be active if introduced into mammals. We, therefore, examined if excision, one part of the transposition reaction, can occur in human and mouse culture cells. A Tol2 clone was introduced into cells and, after incubation, recovered. PCR and sequencing analysis provided evidence for precise and near precise excision in these cells. Tol2 can thus be expected to serve as a material for developing a gene transfer vector and other genetic tools applicable to mammals. It was also suggested that an intact Tol2 element could retain autonomy as a transposable element in mammalian cells.
Akihiko Koga - One of the best experts on this subject based on the ideXlab platform.
-
Spontaneous germline excision of Tol1, a DNA-based transposable element naturally occurring in the Medaka Fish genome.
Genome, 2014Co-Authors: Kohei Watanabe, Hajime Koga, Kodai Nakamura, Akiko Fujita, Akimasa Hattori, Masaru Matsuda, Akihiko KogaAbstract:DNA-based transposable elements are ubiquitous constituents of eukaryotic genomes. Vertebrates are, however, exceptional in that most of their DNA-based elements appear to be inactivated. The Tol1 element of the Medaka Fish, Oryzias latipes, is one of the few elements for which copies containing an undamaged gene have been found. Spontaneous transposition of this element in somatic cells has previously been demonstrated, but there is only indirect evidence for its germline transposition. Here, we show direct evidence of spontaneous excision in the germline. Tyrosinase is the key enzyme in melanin biosynthesis. In an albino laboratory strain of Medaka Fish, which is homozygous for a mutant tyrosinase gene in which a Tol1 copy is inserted, we identified de novo reversion mutations related to melanin pigmentation. The gamete-based reversion rate was as high as 0.4%. The revertant Fish carried the tyrosinase gene from which the Tol1 copy had been excised. We previously reported the germline transposition of Tol2, another DNA-based element that is thought to be a recent invader of the Medaka Fish genome. Tol1 is an ancient resident of the genome. Our results indicate that even an old element can contribute to genetic variation in the host genome as a natural mutator.
-
Distribution of complete and defective copies of the Tol1 transposable element in natural populations of the Medaka Fish Oryzias latipes.
Genes & genetic systems, 2009Co-Authors: Akihiko Koga, Mitsuru Sakaizumi, Yuko Wakamatsu, Satoshi Hamaguchi, Atsuko ShimadaAbstract:DNA-based transposable elements are present in the genomes of various organisms, and generally occur in autonomous and nonautonomous forms, with a good correspondence to complete and defective copies, respectively. In vertebrates, however, the vast majority of DNA-based elements occur only in the nonautonomous form. Until now, the only clear exception known has been the Tol2 element of the Medaka Fish, which still causes mutations in genes of the host species. Here, we report another exception: the Tol1 element of the same species. This element was thought likely to be a "dead" element like the vast majority of vertebrate elements, but recent identification of an autonomous Tol1 copy in a laboratory Medaka strain gave rise to the possibility that the element is still "alive" in Medaka natural populations. We examined variation in the structure of Tol1 copies through genomic Southern blot analysis, and revealed that 10 of the 32 Fish samples examined contained full-length Tol1 copies in their genomes. The frequency at which these copies occur among Tol1 copies is at most 0.5%, yet some of them still have the ability to produce a functional transposase. The Medaka Fish thus harbors two active DNA-based elements in its genome, and is in this respect unique among vertebrates.
-
The Tol1 element of Medaka Fish is transposed with only terminal regions and can deliver large DNA fragments into the chromosomes
Journal of human genetics, 2007Co-Authors: Akihiko Koga, Hiroshi Hori, Yuko Wakamatsu, Ichizo Higashide, Yoriko Kyono-hamaguchi, Satoshi HamaguchiAbstract:Tol1 is an active DNA-based transposable element residing in the genome of the Medaka Fish Oryzias latipes. This element belongs to the hAT transposable element family, of which complete copies have relatively long sequences. In addition, we found that Tol1 elements as long as 18 and 20 kb occur in the Medaka Fish genome. These facts suggest that Tol1 is suitable for carrying large DNA fragments as a gene transfer vector. Focusing on this, we conducted two kinds of manipulations of the element. The first was to eliminate internal regions dispensable for transposition. It was revealed that a Tol1 element consisting of 157-bp left- and 106-bp right-terminal regions could be transposed without a loss of transposition efficiency. Next, we prepared long Tol1 elements by incorporating unrelated DNA fragments into this short Tol1 clone and examined their transposition efficiencies. The transposition frequency decreased as the element size increased. The longest Tol1 element we examined measured 22.1 kb, and its transposition frequency was approximately one fifth that of a 2.1-kb element. However, this frequency was still significantly higher than that of a random integration of DNA into the chromosomes. The element size of 22.1 kb is the longest ever reported for DNA-based elements currently used for mammals. Thus, Tol1 is a superior gene-transfer vector with a large cargo capacity.
-
The Tol1 transposable element of the Medaka Fish moves in human and mouse cells.
Journal of human genetics, 2007Co-Authors: Akihiko Koga, Hiroshi Hori, Atsuko Shimada, Yoriko Kyono-hamaguchi, Toshiya Kuroki, Junko Kusumi, Satoshi HamaguchiAbstract:DNA-based transposable elements can be used as tools for gene engineering and gene therapy. A great advantage over RNA-mediated elements and retroviruses is the simplicity and safety of usage. The Tol1 element of the Medaka Fish Oryzias latipes has structural features of DNA-based elements. Although its excision has already been demonstrated, de novo insertion has not been observed, and a transposase has not been hitherto identified. We first cloned, through in silico search alignments and genomic library screenings, a 4.4-kb Tol1 copy carrying open reading frames and then identified, by mRNA analysis, a 2.9-kb transcript coding for 851 amino acids. The protein product of this transcript catalyzed transposition of a nonautonomous Tol1 copy in human and mouse culture cells. This identification of a fully functional Tol1 transposase could lead to the development of new tools for basic and translational molecular biology applications in mammals.
-
Transposition mechanisms and biothechnology applications of the Medaka Fish tol2 transposable element.
Advances in biophysics, 2004Co-Authors: Akihiko KogaAbstract:Summary The Tol2 element of the Medaka Fish is a member of the hAT ( hobo/Activator/Tam3 ) transposable element family. About 20 copies are present in the Medaka Fish genome and, unlike many other hAT family elements, virtually all the copies are autonomous or potentially autonomous, containing an intact transposase gene. Excision of Tol2 is not precise at the nucleotide sequence level, excision footprints being heterogeneous. In more than half of excision events, however, breakage and rejoining of DNA molecules occur within the 8-bp target site duplication region, removing the entire Tol2 sequence and retaining parts of the target site duplications. In the reminder of the excision events, either the left or the right terminal region is left and the other end is lost together with its flanking region. Thus, there might be two different mechanisms of excision. Insertion of Tol2 occurs without detectable preference for target sequences and creates a target site duplication of exactly 8 bp. In addition to the Medaka Fish and related Fish species, Tol2 transposes in mammalian cells in culture, including human and mouse examples. Autonomy is also retained in these cases. A gene transfer vector using Tol2 has already been established in Fish. Foreign DNA fragements inserted in Tol2 can be efficiently delivered to the chromosomes by transposition. The latest version of the vector contains, between the Tol2 terminal regions, a bacterial drug-resistance gene and a plasmid replication origin. This allows simple recovery of insertion regions, as plasmid DNA, from genomic DNA of transformants. Modification of this system for other vertebrates, especially for mammals, are now in progress.
Norio Suzuki - One of the best experts on this subject based on the ideXlab platform.
-
N (2005) Diverse forms of guanylyl cyclases in Medaka Fish – their genomic structure and phylogenetic relationships to those in vertebrates and invertebrates. Zoolog Sci 22: 819–835
2016Co-Authors: Sayaka Yamagami, Norio SuzukiAbstract:ABSTRACT – Fish species such as Medaka Fish, fugu, and zebraFish contain more guanylyl cyclases (GCs) than do mammals. These GCs can be divided into two types: soluble GCs and membrane GCs. The latter are further divided into four subfamilies: (i) natriuretic peptide receptors, (ii) STa/guanylin receptors, (iii) sensory-organ-specific membrane GCs, and (iv) orphan receptors. Phylogenetic analyses of Medaka Fish GCs, along with those of fugu and zebraFish, suggest that Medaka Fish is a much closer relative to fugu than to zebraFish. Analyses of nucleotide data available on a web sit
-
Diverse Forms of Guanylyl Cyclases in Medaka Fish – Their Genomic Structure and Phylogenetic Relationships to those in Vertebrates and Invertebrates
Zoological Science, 2005Co-Authors: Sayaka Yamagami, Norio SuzukiAbstract:Abstract Fish species such as Medaka Fish, fugu, and zebraFish contain more guanylyl cyclases (GCs) than do mammals. These GCs can be divided into two types: soluble GCs and membrane GCs. The latter are further divided into four subfamilies: (i) natriuretic peptide receptors, (ii) STa/guanylin receptors, (iii) sensory-organ-specific membrane GCs, and (iv) orphan receptors. Phylogenetic analyses of Medaka Fish GCs, along with those of fugu and zebraFish, suggest that Medaka Fish is a much closer relative to fugu than to zebraFish. Analyses of nucleotide data available on a web site (http://www.ncbi.nlm.nih.gov/) of GCs from a range of organisms from bacteria to vertebrates suggest that gene duplication, and possibly chromosomal duplication, play important roles in the divergence of GCs. In particular, the membrane GC genes were generated by chromosomal duplication before the divergence of tetrapods and teleosts.
-
Involvement of General Transcriptional Coactivator PC4 in the Transcription of Medaka Fish Intestine-Specific Membrane Guanylyl Cyclase Gene (OlGC6)
Journal of Biochemistry, 2005Co-Authors: Mina Nakauchi, Kazuyoshi Yonezawa, Ken-ichi Yoshino, Norio SuzukiAbstract:: A recent study showed that the AGACCTTTGC nucleotides sequence (between -90 and -81) contained in the cis-regulatory element in an intestine-specific membrane guanylyl cyclase gene, OlGC6, of the Medaka Fish, Oryzias latipes, are important for the transcription of the gene in mammalian cultured cell line and in Medaka Fish. Using sequence-specific DNA affinity chromatography, we purified a cis-regulatory element-binding protein from a Medaka Fish intestinal nuclear extract and used mass spectrometry to identify it as a Medaka Fish homologue of general transcriptional coactivator PC4, which we designated as OlPC4. The expression of the OlPC4 gene was detected in embryos, as well as in a large variety of tissues of adult Medaka Fish. Using a 17-kDa recombinant OlPC4, we carried out an ultraviolet (UV) cross-linking experiment and an electrophoretic mobility shift assay (EMSA), and demonstrated that the recombinant OlPC4 can be substituted for native OlPC4 in Medaka Fish intestinal nuclear extracts. In CACO-2 cells, cotransfection of the OlGC6-luciferase fusion genes with an OlPC4 expression vector resulted in 1.5-fold stimulation of the OlGC6 promoter.
-
Expression and Function of cGMP-dependent Protein Kinase Type I during Medaka Fish Embryogenesis
The Journal of biological chemistry, 2005Co-Authors: Takehiro Yamamoto, Norio SuzukiAbstract:Abstract We isolated and characterized cDNA clones (PKG Iα and PKG Iβ) for Medaka Fish cGMP-dependent protein kinase (PKG) Iα and Iβ, and demonstrated that both are expressed in the embryos after late gastrula stage. Whole-mount in situ hybridization using each isoform-specific probe revealed that the transcripts of the PKG Iα gene were present in the spinal cord and gill arch, whereas those of the PKG Iβ gene were only weakly expressed in these organs, but highly expressed in the otic vesicles. Injection of PKG Iα-specific morpholino antisense oligonucleotides (Iα-MO) into two-cell stage Medaka Fish embryos caused severe abnormalities in the developing embryos, such as the development of a hammer-like head, fusion of the developing eyes, and degeneration of cells around the eyes, whereas injection of PKG Iβ-specific morpholino antisense oligonucleotides (Iβ-MO) caused fewer abnormalities in the embryos, even when injected at higher concentrations than Iα-MO. The PKG I-overexpressing embryos exhibited smaller eyes and enlargement of the forebrain, a phenotype similar to that observed in the cAMP-dependent protein kinase (PKA)-depressed embryos. In the PKG-deficient embryos, a sonic hedgehog (shh)-target gene, HNF-3β, was expressed weakly, and this phenotype was similar to that observed in the PKA-overexpressing embryos suggesting that the cGMP/PKG signaling pathway is involved in some steps of shh signaling. We also demonstrated that Gli proteins, shh-downstream molecules, are phosphorylated by the NO/cGMP signaling pathway, probably by PKG in NG108-15 neuroblastoma cells. These results imply that PKG and PKA share common substrates and work in an opposite manner during the early embryogenesis of Medaka Fish.
-
Diverse forms of guanylyl cyclases in Medaka Fish -- their genomic structure and phylogenetic relationships to those in vertebrates and invertebrates.
Zoological science, 2005Co-Authors: Sayaka Yamagami, Norio SuzukiAbstract:Fish species such as Medaka Fish, fugu, and zebraFish contain more guanylyl cyclases (GCs) than do mammals. These GCs can be divided into two types: soluble GCs and membrane GCs. The latter are further divided into four subfamilies: (i) natriuretic peptide receptors, (ii) STa/guanylin receptors, (iii) sensory-organ-specific membrane GCs, and (iv) orphan receptors. Phylogenetic analyses of Medaka Fish GCs, along with those of fugu and zebraFish, suggest that Medaka Fish is a much closer relative to fugu than to zebraFish. Analyses of nucleotide data available on a web site (http://www.ncbi. nlm.nih.gov/) of GCs from a range of organisms from bacteria to vertebrates suggest that gene duplication, and possibly chromosomal duplication, play important roles in the divergence of GCs. In particular, the membrane GC genes were generated by chromosomal duplication before the divergence of tetrapods and teleosts.
Takehiro Yamamoto - One of the best experts on this subject based on the ideXlab platform.
-
Expression and Function of cGMP-dependent Protein Kinase Type I during Medaka Fish Embryogenesis
The Journal of biological chemistry, 2005Co-Authors: Takehiro Yamamoto, Norio SuzukiAbstract:Abstract We isolated and characterized cDNA clones (PKG Iα and PKG Iβ) for Medaka Fish cGMP-dependent protein kinase (PKG) Iα and Iβ, and demonstrated that both are expressed in the embryos after late gastrula stage. Whole-mount in situ hybridization using each isoform-specific probe revealed that the transcripts of the PKG Iα gene were present in the spinal cord and gill arch, whereas those of the PKG Iβ gene were only weakly expressed in these organs, but highly expressed in the otic vesicles. Injection of PKG Iα-specific morpholino antisense oligonucleotides (Iα-MO) into two-cell stage Medaka Fish embryos caused severe abnormalities in the developing embryos, such as the development of a hammer-like head, fusion of the developing eyes, and degeneration of cells around the eyes, whereas injection of PKG Iβ-specific morpholino antisense oligonucleotides (Iβ-MO) caused fewer abnormalities in the embryos, even when injected at higher concentrations than Iα-MO. The PKG I-overexpressing embryos exhibited smaller eyes and enlargement of the forebrain, a phenotype similar to that observed in the cAMP-dependent protein kinase (PKA)-depressed embryos. In the PKG-deficient embryos, a sonic hedgehog (shh)-target gene, HNF-3β, was expressed weakly, and this phenotype was similar to that observed in the PKA-overexpressing embryos suggesting that the cGMP/PKG signaling pathway is involved in some steps of shh signaling. We also demonstrated that Gli proteins, shh-downstream molecules, are phosphorylated by the NO/cGMP signaling pathway, probably by PKG in NG108-15 neuroblastoma cells. These results imply that PKG and PKA share common substrates and work in an opposite manner during the early embryogenesis of Medaka Fish.
-
Genomic Structure and Expression of the Soluble Guanylyl Cyclase α2 Subunit Gene in the Medaka Fish Oryzias latipes
Zoological science, 2003Co-Authors: Yuko Yao, Hiroshi Mitani, Hiroshi Hori, Makiko Tsutsumi, Akihiro Shima, Kiyoshi Naruse, Takehiro Yamamoto, Masaru Matsuda, Shuichi Asakawa, Nobuyoshi ShimizuAbstract:Abstract A cDNA clone encoding the soluble guanylyl cyclase α2 subunit was isolated from Medaka Fish (Oryzias latipes) and designated as OlGCS-α2. The OlGCS-α2 cDNA was 3192 bp in length and the open reading frame (ORF) encodes a protein of 805 amino acids. The deduced amino acid sequence has high similarity to that of the mammalian α2 subunit gene except for the N-terminal regulatory domain. The C-terminal 5 amino acids, “RETSL”, which have been reported to interact with the post synaptic density protein (PSD)-95 were conserved. An RNase protection assay with adult Fish organs showed that OlGCS-α2 was expressed mainly in the brain and testis. The complete nucleotide sequence (about 41 kbp) of the OlGCS-α2 genomic DNA clone isolated from a Medaka Fish BAC library indicated that the OlGCS-α2 gene consisted of 9 exons and 8 introns. The 5′-flanking region and larger introns, such as introns 1, 4, and 7, contained the several fragments conserved in the nucleotide sequences of Rex6 (non-long terminal repeat r...
-
Promoter activity of the 5'-flanking regions of Medaka Fish soluble guanylate cyclase alpha1 and beta1 subunit genes.
The Biochemical journal, 2002Co-Authors: Takehiro Yamamoto, Norio SuzukiAbstract:We examined the spatial expression pattern of Medaka Fish (Oryzias latipes) soluble guanylate cyclase alpha(1) and beta(1) subunit genes, OlGCS-alpha(1) and OlGCS-beta(1), and characterized the 5'-flanking region required for expression of both genes by introducing various promoter-luciferase fusion-gene constructs into COS-1 cells and Medaka Fish embryos. The OlGCS-alpha(1) and OlGCS-beta(1) gene transcripts were detected in whole brain and kidney in 7-day and 9-day embryos. Primer-extension analysis demonstrated that there were no differences among various adult organs (brain, eye, kidney, ovary and testis) in the transcription start site of the OlGCS-alpha(1) and OlGCS-beta(1) genes. Neither gene contained the functional TATA box within its 5'-flanking region, and the basal promoter activity was found between nucleotides +33 and +42 in the OlGCS-alpha(1) gene and between nucleotides +146 and +155 in the OlGCS-beta(1) gene. In the assay of Medaka Fish embryos, the 5'-flanking region of the OlGCS-beta(1) gene exhibited lower promoter activity than that of the OlGCS-alpha(1) gene. In the experiments on dual-luciferase fusion-gene constructs, the 5'-flanking region of the OlGCS-alpha(1) gene connected to the 5'-flanking region of the OlGCS-beta(1) gene was introduced into Medaka Fish embryos, and the 5'-flanking regions of both subunit genes were shown to mutually influence each other's promoter activity.
-
Promoter activity of the 5′-flanking regions of Medaka Fish soluble guanylate cyclase α1 and β1 subunit genes
Biochemical Journal, 2002Co-Authors: Takehiro Yamamoto, Norio SuzukiAbstract:We examined the spatial expression pattern of Medaka Fish (Oryzias latipes) soluble guanylate cyclase alpha(1) and beta(1) subunit genes, OlGCS-alpha(1) and OlGCS-beta(1), and characterized the 5'-flanking region required for expression of both genes by introducing various promoter-luciferase fusion-gene constructs into COS-1 cells and Medaka Fish embryos. The OlGCS-alpha(1) and OlGCS-beta(1) gene transcripts were detected in whole brain and kidney in 7-day and 9-day embryos. Primer-extension analysis demonstrated that there were no differences among various adult organs (brain, eye, kidney, ovary and testis) in the transcription start site of the OlGCS-alpha(1) and OlGCS-beta(1) genes. Neither gene contained the functional TATA box within its 5'-flanking region, and the basal promoter activity was found between nucleotides +33 and +42 in the OlGCS-alpha(1) gene and between nucleotides +146 and +155 in the OlGCS-beta(1) gene. In the assay of Medaka Fish embryos, the 5'-flanking region of the OlGCS-beta(1) gene exhibited lower promoter activity than that of the OlGCS-alpha(1) gene. In the experiments on dual-luciferase fusion-gene constructs, the 5'-flanking region of the OlGCS-alpha(1) gene connected to the 5'-flanking region of the OlGCS-beta(1) gene was introduced into Medaka Fish embryos, and the 5'-flanking regions of both subunit genes were shown to mutually influence each other's promoter activity.
-
Promoter activity of the 5′-flanking regions of Medaka Fish soluble guanylate cyclase α1 and β1 subunit genes
Biochemical Journal, 2002Co-Authors: Takehiro Yamamoto, Norio SuzukiAbstract:We examined the spatial expression pattern of Medaka Fish (Oryzias latipes) soluble guanylate cyclase α1 and β1 subunit genes, OlGCS-α1 and OlGCS-β1, and characterized the 5′-flanking region required for expression of both genes by introducing various promoter-luciferase fusion-gene constructs into COS-1 cells and Medaka Fish embryos. The OlGCS-α1 and OlGCS-β1 gene transcripts were detected in whole brain and kidney in 7-day and 9-day embryos. Primer-extension analysis demonstrated that there were no differences among various adult organs (brain, eye, kidney, ovary and testis) in the transcription start site of the OlGCS-α1 and OlGCS-β1 genes. Neither gene contained the functional TATA box within its 5′-flanking region, and the basal promoter activity was found between nucleotides +33 and +42 in the OlGCS-α1 gene and between nucleotides +146 and +155 in the OlGCS-β1 gene. In the assay of Medaka Fish embryos, the 5′-flanking region of the OlGCS-β1 gene exhibited lower promoter activity than that of the OlGCS-α1 gene. In the experiments on dual-luciferase fusion-gene constructs, the 5′-flanking region of the OlGCS-α1 gene connected to the 5′-flanking region of the OlGCS-β1 gene was introduced into Medaka Fish embryos, and the 5′-flanking regions of both subunit genes were shown to mutually influence each other's promoter activity.
Satoshi Hamaguchi - One of the best experts on this subject based on the ideXlab platform.
-
Distribution of complete and defective copies of the Tol1 transposable element in natural populations of the Medaka Fish Oryzias latipes.
Genes & genetic systems, 2009Co-Authors: Akihiko Koga, Mitsuru Sakaizumi, Yuko Wakamatsu, Satoshi Hamaguchi, Atsuko ShimadaAbstract:DNA-based transposable elements are present in the genomes of various organisms, and generally occur in autonomous and nonautonomous forms, with a good correspondence to complete and defective copies, respectively. In vertebrates, however, the vast majority of DNA-based elements occur only in the nonautonomous form. Until now, the only clear exception known has been the Tol2 element of the Medaka Fish, which still causes mutations in genes of the host species. Here, we report another exception: the Tol1 element of the same species. This element was thought likely to be a "dead" element like the vast majority of vertebrate elements, but recent identification of an autonomous Tol1 copy in a laboratory Medaka strain gave rise to the possibility that the element is still "alive" in Medaka natural populations. We examined variation in the structure of Tol1 copies through genomic Southern blot analysis, and revealed that 10 of the 32 Fish samples examined contained full-length Tol1 copies in their genomes. The frequency at which these copies occur among Tol1 copies is at most 0.5%, yet some of them still have the ability to produce a functional transposase. The Medaka Fish thus harbors two active DNA-based elements in its genome, and is in this respect unique among vertebrates.
-
The Tol1 element of Medaka Fish is transposed with only terminal regions and can deliver large DNA fragments into the chromosomes
Journal of human genetics, 2007Co-Authors: Akihiko Koga, Hiroshi Hori, Yuko Wakamatsu, Ichizo Higashide, Yoriko Kyono-hamaguchi, Satoshi HamaguchiAbstract:Tol1 is an active DNA-based transposable element residing in the genome of the Medaka Fish Oryzias latipes. This element belongs to the hAT transposable element family, of which complete copies have relatively long sequences. In addition, we found that Tol1 elements as long as 18 and 20 kb occur in the Medaka Fish genome. These facts suggest that Tol1 is suitable for carrying large DNA fragments as a gene transfer vector. Focusing on this, we conducted two kinds of manipulations of the element. The first was to eliminate internal regions dispensable for transposition. It was revealed that a Tol1 element consisting of 157-bp left- and 106-bp right-terminal regions could be transposed without a loss of transposition efficiency. Next, we prepared long Tol1 elements by incorporating unrelated DNA fragments into this short Tol1 clone and examined their transposition efficiencies. The transposition frequency decreased as the element size increased. The longest Tol1 element we examined measured 22.1 kb, and its transposition frequency was approximately one fifth that of a 2.1-kb element. However, this frequency was still significantly higher than that of a random integration of DNA into the chromosomes. The element size of 22.1 kb is the longest ever reported for DNA-based elements currently used for mammals. Thus, Tol1 is a superior gene-transfer vector with a large cargo capacity.
-
The Tol1 transposable element of the Medaka Fish moves in human and mouse cells.
Journal of human genetics, 2007Co-Authors: Akihiko Koga, Hiroshi Hori, Atsuko Shimada, Yoriko Kyono-hamaguchi, Toshiya Kuroki, Junko Kusumi, Satoshi HamaguchiAbstract:DNA-based transposable elements can be used as tools for gene engineering and gene therapy. A great advantage over RNA-mediated elements and retroviruses is the simplicity and safety of usage. The Tol1 element of the Medaka Fish Oryzias latipes has structural features of DNA-based elements. Although its excision has already been demonstrated, de novo insertion has not been observed, and a transposase has not been hitherto identified. We first cloned, through in silico search alignments and genomic library screenings, a 4.4-kb Tol1 copy carrying open reading frames and then identified, by mRNA analysis, a 2.9-kb transcript coding for 851 amino acids. The protein product of this transcript catalyzed transposition of a nonautonomous Tol1 copy in human and mouse culture cells. This identification of a fully functional Tol1 transposase could lead to the development of new tools for basic and translational molecular biology applications in mammals.