27 results on '"Akane Kawaguchi"'
Search Results
2. Squalomix: shark and ray genome analysis consortium and its data sharing platform [version 1; peer review: 2 approved]
- Author
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John Rozewicki, Kazuaki Yamaguchi, Osamu Nishimura, Ryo Misawa, Takashi Asahida, Mitsumasa Koyanagi, Akihisa Terakita, Filipe Castro, André Machado, Milton Tan, Salvatore D'Aniello, Shotaro Hirase, Akane Kawaguchi, Chiharu Tanegashima, Akinori Teramura, Masaru Yagura, Taiki Niwa, Kaori Tatsumi, Yuta Ohishi, Susumu Hyodo, Mitsutaka Kadota, Itsuki Kiyatake, Keiichi Sato, Kazuyuki Yamada, Kiyonori Nishida, Yasuko Semba, Shinya Yamauchi, Sho Tanaka, Tatsuya Sakamoto, Norio Miyamoto, Atsushi Toyoda, Rui Matsumoto, Iker Irisarri, Atsuko Yamaguchi, Tazro Ohta, Kiyomi Murakumo, Junna Kawasaki, Masayuki Horie, Yoshinobu Uno, and Shigehiro Kuraku
- Subjects
Shark ,ray ,chimaera ,biodiversity genomics ,whole genome sequencing ,karyotype ,eng ,Medicine ,Science - Abstract
The taxon Elasmobranchii (sharks and rays) contains one of the long-established evolutionary lineages of vertebrates with a tantalizing collection of species occupying critical aquatic habitats. To overcome the current limitation in molecular resources, we launched the Squalomix Consortium in 2020 to promote a genome-wide array of molecular approaches, specifically targeting shark and ray species. Among the various bottlenecks in working with elasmobranchs are their elusiveness and low fecundity as well as the large and highly repetitive genomes. Their peculiar body fluid composition has also hindered the establishment of methods to perform routine cell culturing required for their karyotyping. In the Squalomix consortium, these obstacles are expected to be solved through a combination of in-house cytological techniques including karyotyping of cultured cells, chromatin preparation for Hi-C data acquisition, and high fidelity long-read sequencing. The resources and products obtained in this consortium, including genome and transcriptome sequences, a genome browser powered by JBrowse2 to visualize sequence alignments, and comprehensive matrices of gene expression profiles for selected species are accessible through https://github.com/Squalomix/info.
- Published
- 2022
- Full Text
- View/download PDF
3. Draft genome of Dugesia japonica provides insights into conserved regulatory elements of the brain restriction gene nou-darake in planarians
- Author
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Yang An, Akane Kawaguchi, Chen Zhao, Atsushi Toyoda, Ali Sharifi-Zarchi, Seyed Ahmad Mousavi, Reza Bagherzadeh, Takeshi Inoue, Hajime Ogino, Asao Fujiyama, Hamidreza Chitsaz, Hossein Baharvand, and Kiyokazu Agata
- Subjects
Planarian ,Dugesia japonica ,Genome ,Conserved non-coding elements ,Nou-darake ,Zoology ,QL1-991 - Abstract
Abstract Background Planarians are non-parasitic Platyhelminthes (flatworms) famous for their regeneration ability and for having a well-organized brain. Dugesia japonica is a typical planarian species that is widely distributed in the East Asia. Extensive cellular and molecular experimental methods have been developed to identify the functions of thousands of genes in this species, making this planarian a good experimental model for regeneration biology and neurobiology. However, no genome-level information is available for D. japonica, and few gene regulatory networks have been identified thus far. Results To obtain whole-genome information on this species and to study its gene regulatory networks, we extracted genomic DNA from 200 planarians derived from a laboratory-bred asexual clonal strain, and sequenced 476 Gb of data by second-generation sequencing. Kmer frequency graphing and fosmid sequence analysis indicated a complex genome that would be difficult to assemble using second-generation sequencing short reads. To address this challenge, we developed a new assembly strategy and improved the de novo genome assembly, producing a 1.56 Gb genome sequence (DjGenome ver1.0, including 202,925 scaffolds and N50 length 27,741 bp) that covers 99.4% of all 19,543 genes in the assembled transcriptome, although the genome is fragmented as 80% of the genome consists of repeated sequences (genomic frequency ≥ 2). By genome comparison between two planarian genera, we identified conserved non-coding elements (CNEs), which are indicative of gene regulatory elements. Transgenic experiments using Xenopus laevis indicated that one of the CNEs in the Djndk gene may be a regulatory element, suggesting that the regulation of the ndk gene and the brain formation mechanism may be conserved between vertebrates and invertebrates. Conclusion This draft genome and CNE analysis will contribute to resolving gene regulatory networks in planarians. The genome database is available at: http://www.planarian.jp.
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- 2018
- Full Text
- View/download PDF
4. Squalomix: shark and ray genome analysis consortium and its data sharing platform [version 1; peer review: 2 approved]
- Author
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Osamu Nishimura, John Rozewicki, Kazuaki Yamaguchi, Kaori Tatsumi, Yuta Ohishi, Tazro Ohta, Masaru Yagura, Taiki Niwa, Chiharu Tanegashima, Akinori Teramura, Shotaro Hirase, Akane Kawaguchi, Milton Tan, Salvatore D'Aniello, Filipe Castro, André Machado, Mitsumasa Koyanagi, Akihisa Terakita, Ryo Misawa, Masayuki Horie, Junna Kawasaki, Takashi Asahida, Atsuko Yamaguchi, Kiyomi Murakumo, Rui Matsumoto, Iker Irisarri, Norio Miyamoto, Atsushi Toyoda, Sho Tanaka, Tatsuya Sakamoto, Yasuko Semba, Shinya Yamauchi, Kazuyuki Yamada, Kiyonori Nishida, Itsuki Kiyatake, Keiichi Sato, Susumu Hyodo, Mitsutaka Kadota, Yoshinobu Uno, and Shigehiro Kuraku
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Data Note ,Articles ,Shark ,ray ,chimaera ,biodiversity genomics ,whole genome sequencing ,karyotype - Abstract
The taxon Elasmobranchii (sharks and rays) contains one of the long-established evolutionary lineages of vertebrates with a tantalizing collection of species occupying critical aquatic habitats. To overcome the current limitation in molecular resources, we launched the Squalomix Consortium in 2020 to promote a genome-wide array of molecular approaches, specifically targeting shark and ray species. Among the various bottlenecks in working with elasmobranchs are their elusiveness and low fecundity as well as the large and highly repetitive genomes. Their peculiar body fluid composition has also hindered the establishment of methods to perform routine cell culturing required for their karyotyping. In the Squalomix consortium, these obstacles are expected to be solved through a combination of in-house cytological techniques including karyotyping of cultured cells, chromatin preparation for Hi-C data acquisition, and high fidelity long-read sequencing. The resources and products obtained in this consortium, including genome and transcriptome sequences, a genome browser powered by JBrowse2 to visualize sequence alignments, and comprehensive matrices of gene expression profiles for selected species are accessible through https://github.com/Squalomix/info.
- Published
- 2022
- Full Text
- View/download PDF
5. Chromatin states at homeoprotein loci distinguish axolotl limb segments prior to regeneration
- Author
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Akane Kawaguchi, Jingkui Wang, Dunja Knapp, Prayag Murawala, Sergej Nowoshilow, Wouter Masselink, Yuka Taniguchi-Sugiura, Jifeng Fei, and Elly M. Tanaka
- Abstract
The salamander limb regenerates only the missing portion. Each limb segment can only form segments equivalent to- or more distal to their own identity, relying on a property termed “positional information”. How positional information is encoded in limb cells has been unknown. By cell-type-specific chromatin profiling of upper arm, lower arm, and hand, we found segment-specific levels of histone H3K27me3 at limb homeoprotein gene loci but not their upstream regulators, constituting an intrinsic segment information code. During regeneration, regeneration-specific regulatory elements became active prior to the re-appearance of developmental regulatory elements. This means that, in the hand segment, the permissive chromatin state of the hand homeoprotein geneHoxA13engages with regeneration regulatory elements, bypassing the upper limb program.
- Published
- 2022
6. Chromosome Conformation Capture for Large Genomes
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Akane Kawaguchi and Elly M. Tanaka
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- 2022
7. Chromosome Conformation Capture for Large Genomes
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Akane, Kawaguchi and Elly M, Tanaka
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Genome ,Animals ,High-Throughput Nucleotide Sequencing ,Nucleic Acid Conformation ,Genomics ,Chromosomes ,Chromatin - Abstract
The gigantic 32Gb Axolotl genome inspires fascinating questions such as: how such a big genome is organized and packed in nuclei and how regulation of gene transcription can happen over such large genomic distances. Currently, there are many technical challenges when we investigate chromatin architecture in axolotl. For example, probing promoter-enhancer interactions in such a large genome. Chromatin capture methods (e.g., Chromatin Conformation Capture) have been used in a variety of species. The large size of the axolotl nuclei and its genome requires the adaptation of such methods. Here, we describe a detailed protocol for high-throughput genome-wide conformation capture (Hi-C) using axolotl limb cells. This Hi-C library preparation protocol can also be used to prepare libraries from other nonmodel organisms such as Lungfish and Cephalopods. We believe that our protocol could be useful for a variety of animal systems including other salamanders.
- Published
- 2022
8. Taming chlorophylls by early eukaryotes underpinned algal interactions and the diversification of the eukaryotes on the oxygenated Earth
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Jun Kawahara, Toshiki Matsuda, Akira Shihongi, Tomoko Yoshino, Moe Maruyama, Akiko Yokoyama, Yoko Hamamoto, Man Chen, Goro Tanifuji, Sebastian Hess, Mami Nomura, Takahiro Umetani, Takashi Shiratori, Yingchun Gong, Masashi Tsuchiya, Maiko Kagami, Mitsufumi Matsumoto, Shin-ya Miyagishima, Takahiro Ishikawa, Rina Higuchi, Junya Taira, Atsushi Nakamura, Yuichiro Kashiyama, Charles Bachy, Akane Kawaguchi, Akihiro Yamamoto, Akihiro Uzuka, Andrés Gutiérrez-Rodríguez, Noriaki Namba, Masanobu Kawachi, Tadanobu Maruyama, Akinori Yabuki, Daiske Honda, Yusuke Kinoshita, Masami Nakazawa, Motoki Kayama, Mengyun Wang, Tsuyoshi Tanaka, Hitoshi Tamiaki, Yoshihisa Hirakawa, Fabrice Not, Kensuke Seto, Toshinobu Suzaki, and Aika Yamaguchi
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Chlorophyll ,Chloroplasts ,Photosynthesis ,Microbiology ,Biochemistry ,Article ,Microbial ecology ,03 medical and health sciences ,chemistry.chemical_compound ,Symbiosis ,Botany ,Microalgae ,Cellular microbiology ,Ecology, Evolution, Behavior and Systematics ,Ecosystem ,Phylogeny ,030304 developmental biology ,0303 health sciences ,biology ,Endosymbiosis ,Phototroph ,030306 microbiology ,Archaeplastida ,Eukaryota ,Biogeochemistry ,biology.organism_classification ,Chloroplast ,Oxygen ,chemistry ,Eukaryote - Abstract
Extant eukaryote ecology is primarily sustained by oxygenic photosynthesis, in which chlorophylls play essential roles. The exceptional photosensitivity of chlorophylls allows them to harvest solar energy for photosynthesis, but on the other hand, they also generate cytotoxic reactive oxygen species. A risk of such phototoxicity of the chlorophyll must become particularly prominent upon dynamic cellular interactions that potentially disrupt the mechanisms that are designed to quench photoexcited chlorophylls in the phototrophic cells. Extensive examination of a wide variety of phagotrophic, parasitic, and phototrophic microeukaryotes demonstrates that a catabolic process that converts chlorophylls into nonphotosensitive 13(2),17(3)-cyclopheophorbide enols (CPEs) is phylogenetically ubiquitous among extant eukaryotes. The accumulation of CPEs is identified in phagotrophic algivores belonging to virtually all major eukaryotic assemblages with the exception of Archaeplastida, in which no algivorous species have been reported. In addition, accumulation of CPEs is revealed to be common among phototrophic microeukaryotes (i.e., microalgae) along with dismantling of their secondary chloroplasts. Thus, we infer that CPE-accumulating chlorophyll catabolism (CACC) primarily evolved among algivorous microeukaryotes to detoxify chlorophylls in an early stage of their evolution. Subsequently, it also underpinned photosynthetic endosymbiosis by securing close interactions with photosynthetic machinery containing abundant chlorophylls, which led to the acquisition of secondary chloroplasts. Our results strongly suggest that CACC, which allowed the consumption of oxygenic primary producers, ultimately permitted the successful radiation of the eukaryotes throughout and after the late Proterozoic global oxygenation.
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- 2019
9. Fabrication of Human-Friendly Liquid Crystal Materials with α-Ionone
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Ruri Aoki, Seiichi Furumi, Masashi Fukawa, Kenichiro Hayata, Mami Furukawa, and Akane Kawaguchi
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chemistry.chemical_compound ,Materials science ,Fabrication ,Polymers and Plastics ,chemistry ,Chemical engineering ,Liquid crystal ,Lyotropic liquid crystal ,Organic Chemistry ,Materials Chemistry ,Bragg's law ,Cellulose ,Ionone - Published
- 2019
10. Syntheses and Properties of Cellulosic Derivatives for Reflection Color Films
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Mami Furukawa, Ruri Aoki, Akane Kawaguchi, Kenichiro Hayata, Seiichi Furumi, and Masashi Fukawa
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Materials science ,Reflection (mathematics) ,Polymers and Plastics ,Cellulosic ethanol ,business.industry ,Organic Chemistry ,Materials Chemistry ,Bragg's law ,Optoelectronics ,business ,Thermotropic crystal - Published
- 2019
11. The giant axolotl genome uncovers the evolution, scaling, and transcriptional control of complex gene loci
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Pietro Tardivo, Elly M. Tanaka, Francisco Falcon, J. Joshua Smith, S. Randal Voss, Sergej Nowoshilow, Melissa C. Keinath, Akane Kawaguchi, Siegfried Schloissnig, Nataliya Timoshevskaya, and Leo Otsuki
- Subjects
Context (language use) ,axolotl ,Biology ,Genome ,Chromosomes ,Evolution, Molecular ,Axolotl ,Animals ,Gene ,Genome size ,Synteny ,Regulation of gene expression ,Multidisciplinary ,Biological Sciences ,biology.organism_classification ,Topological Associating Domains ,Ambystoma mexicanum ,Evolutionary biology ,Genetic Loci ,regeneration ,genome assembly ,Transcriptome ,Orthologous Gene ,Developmental Biology - Abstract
Significance The axolotl is an important model organism because it is a tetrapod with a similar body plan to humans. Unlike humans, the axolotl regenerates limbs and other complex tissues. Therefore, the axolotl contributes to understanding evolution, development, and regeneration. With sophisticated tools for gene modification and tissue labeling, a fully assembled genome sequence was a sorely missing resource. Assembly was difficult because the genome size is 10× that of humans. Here, we use a cross-linking strategy called Hi-C to link together fragmented genome sequences to chromosome scale. We show that gene regulation occurs over very large genomic distances and that mitotic chromosomes are packaged efficiently., Vertebrates harbor recognizably orthologous gene complements but vary 100-fold in genome size. How chromosomal organization scales with genome expansion is unclear, and how acute changes in gene regulation, as during axolotl limb regeneration, occur in the context of a vast genome has remained a riddle. Here, we describe the chromosome-scale assembly of the giant, 32 Gb axolotl genome. Hi-C contact data revealed the scaling properties of interphase and mitotic chromosome organization. Analysis of the assembly yielded understanding of the evolution of large, syntenic multigene clusters, including the Major Histocompatibility Complex (MHC) and the functional regulatory landscape of the Fibroblast Growth Factor 8 (Axfgf8) region. The axolotl serves as a primary model for studying successful regeneration.
- Published
- 2021
12. Giant lungfish genome elucidates the conquest of land by vertebrates
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Jean-Nicolas Volff, Oleg Simakov, Paolo Franchini, Susanne Kneitz, Iker Irisarri, Manfred Schartl, Kang Du, Thorsten Burmester, Wai Yee Wong, Peiwen Xiong, Axel Meyer, Elly M. Tanaka, Joost M. Woltering, Sergej Nowoshilow, Akane Kawaguchi, Andrej Fabrizius, Herman P. Spaink, Corentin Dechaud, and Siegfried Schloissnig
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Evolutionary biology ,Genome ,Mice ,0302 clinical medicine ,terrestrialization ,Gait ,Lung ,Phylogeny ,Lungfish ,0303 health sciences ,Multidisciplinary ,biology ,Air ,Respiration ,Fishes ,Genes, Homeobox ,Vertebrate ,Gene Expression Regulation, Developmental ,Genomics ,Adaptation, Physiological ,Biological Evolution ,Smell ,Phylogenetics ,Vertebrates ,Animal Fins ,Female ,Vomeronasal Organ ,conquer of land ,Sarcopterygii ,Genome evolution ,Genome sequencing ,preadaptations ,Synteny ,Chromosomes ,Article ,Evolutionary genetics ,03 medical and health sciences ,biology.animal ,ddc:570 ,Animals ,Humans ,030304 developmental biology ,Human evolutionary genetics ,Bayes Theorem ,Extremities ,Molecular Sequence Annotation ,biology.organism_classification ,Long Interspersed Nucleotide Elements ,Microchromosome ,Evolutionay biology ,030217 neurology & neurosurgery - Abstract
Lungfishes belong to lobe-fined fish (Sarcopterygii) that, in the Devonian period, ‘conquered’ the land and ultimately gave rise to all land vertebrates, including humans1–3. Here we determine the chromosome-quality genome of the Australian lungfish (Neoceratodus forsteri), which is known to have the largest genome of any animal. The vast size of this genome, which is about 14× larger than that of humans, is attributable mostly to huge intergenic regions and introns with high repeat content (around 90%), the components of which resemble those of tetrapods (comprising mainly long interspersed nuclear elements) more than they do those of ray-finned fish. The lungfish genome continues to expand independently (its transposable elements are still active), through mechanisms different to those of the enormous genomes of salamanders. The 17 fully assembled lungfish macrochromosomes maintain synteny to other vertebrate chromosomes, and all microchromosomes maintain conserved ancient homology with the ancestral vertebrate karyotype. Our phylogenomic analyses confirm previous reports that lungfish occupy a key evolutionary position as the closest living relatives to tetrapods4,5, underscoring the importance of lungfish for understanding innovations associated with terrestrialization. Lungfish preadaptations to living on land include the gain of limb-like expression in developmental genes such as hoxc13 and sall1 in their lobed fins. Increased rates of evolution and the duplication of genes associated with obligate air-breathing, such as lung surfactants and the expansion of odorant receptor gene families (which encode proteins involved in detecting airborne odours), contribute to the tetrapod-like biology of lungfishes. These findings advance our understanding of this major transition during vertebrate evolution., A chromosome-quality genome of the lungfish Neoceratodus fosteri sheds light on the development of obligate air-breathing and the gain of limb-like gene expression in lobed fins, providing insights into the water-to-land transition in vertebrate evolution.
- Published
- 2021
13. Frozen Storage of Tea Leaves after Withering for Use in Black Tea Processing
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Akane Kawaguchi, Hiroto Sato, Namiko Ikeda, Tubasa Kawano, and Yasuaki Tamura
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Horticulture ,Chemistry ,General Medicine ,Frozen storage ,Black tea - Published
- 2018
14. Co-accumulation of cis-regulatory and coding mutations during the pseudogenization of the Xenopus laevis homoeologs six6.L and six6.S
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Nanoka Suzuki, Yui Iwata, Tatsuki Kumada, Haruki Ochi, Mikio Tanouchi, Akane Kawaguchi, and Hajime Ogino
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0301 basic medicine ,Embryo, Nonmammalian ,Xenopus ,Regulatory Sequences, Nucleic Acid ,Xenopus Proteins ,Biology ,medicine.disease_cause ,Genome ,Retina ,Animals, Genetically Modified ,Evolution, Molecular ,Xenopus laevis ,03 medical and health sciences ,Genes, Duplicate ,Gene Duplication ,Sequence Homology, Nucleic Acid ,Gene duplication ,medicine ,Animals ,Protein Isoforms ,Amino Acid Sequence ,Enhancer ,Molecular Biology ,In Situ Hybridization ,Phylogeny ,Homeodomain Proteins ,Genetics ,Mutation ,Base Sequence ,Sequence Homology, Amino Acid ,Gene Expression Regulation, Developmental ,Cell Biology ,biology.organism_classification ,Enhancer Elements, Genetic ,030104 developmental biology ,Subfunctionalization ,Homeobox ,Neofunctionalization ,Pseudogenes ,Developmental Biology - Abstract
Common models for the evolution of duplicated genes after genome duplication are subfunctionalization, neofunctionalization, and pseudogenization. Although the crucial roles of cis-regulatory mutations in subfunctionalization are well-documented, their involvement in pseudogenization and/or neofunctionalization remains unclear. We addressed this issue by investigating the evolution of duplicated homeobox genes, six6.L and six6.S, in the allotetraploid frog Xenopus laevis. Based on a comparative expression analysis, we observed similar eye-specific expression patterns for the two loci and their single ortholog in the ancestral-type diploid species Xenopus tropicalis. However, we detected lower levels of six6.S expression than six6.L expression. The six6.S enhancer sequence was more highly diverged from the orthologous enhancer of X. tropicalis than the six6.L enhancer, and showed weaker activity in a transgenic reporter assay. Based on a phylogenetic analysis of the protein sequences, we observed greater divergence between X. tropicalis Six6 and Six6.S than between X. tropicalis Six6 and Six6.L, and the observed mutations were reminiscent of a microphthalmia mutation in human SIX6. Misexpression experiments showed that six6.S has weaker eye-enlarging activity than six6.L, and targeted disruption of six6.L reduced the eye size more significantly than that of six6.S. These results suggest that enhancer attenuation stimulates the accumulation of hypomorphic coding mutations, or vice versa, in one duplicated gene copy and facilitates pseudogenization. We also underscore the value of the allotetraploid genome of X. laevis as a resource for studying latent pathogenic mutations.
- Published
- 2017
15. Live Imaging of Axolotl Digit Regeneration Reveals Spatiotemporal Choreography of Diverse Connective Tissue Progenitor Pools
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Maritta Schuez, Osvaldo Chara, Joshua D. Currie, Ricardo Moreno Traspas, Elly M. Tanaka, and Akane Kawaguchi
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limb regeneration ,0301 basic medicine ,LIMB REGENERATION ,Time Factors ,cell migration ,LIVE IMAGING ,axolotl ,skeletal regeneration ,Animals, Genetically Modified ,purl.org/becyt/ford/1 [https] ,0302 clinical medicine ,Cell Movement ,connective tissue ,Platelet-Derived Growth Factor ,biology ,AXOLOTL ,Stem Cells ,Cell migration ,live imaging ,Dermis ,Anatomy ,PDGF SIGNALING ,Cell biology ,medicine.anatomical_structure ,Stem cell ,Blastema ,CIENCIAS NATURALES Y EXACTAS ,Signal Transduction ,Otras Ciencias Biológicas ,Connective tissue ,BRAINBOW ,Models, Biological ,Article ,Bone and Bones ,General Biochemistry, Genetics and Molecular Biology ,Fibroblast migration ,Ciencias Biológicas ,03 medical and health sciences ,PDGF signaling ,Chondrocytes ,Imaging, Three-Dimensional ,Axolotl ,medicine ,Animals ,Regeneration ,Compartment (development) ,purl.org/becyt/ford/1.6 [https] ,Molecular Biology ,Ciencias Exactas ,Cell Proliferation ,Regeneration (biology) ,Extremities ,Cell Biology ,Fibroblasts ,blastema formation ,biology.organism_classification ,SKELETAL REGENERATION ,Clone Cells ,Ambystoma mexicanum ,body regions ,030104 developmental biology ,BLASTEMA FORMATION ,CELL MIGRATION ,brainbow ,CONNECTIVE TISSUE ,Pericytes ,030217 neurology & neurosurgery ,Developmental Biology - Abstract
Summary Connective tissues—skeleton, dermis, pericytes, fascia—are a key cell source for regenerating the patterned skeleton during axolotl appendage regeneration. This complexity has made it difficult to identify the cells that regenerate skeletal tissue. Inability to identify these cells has impeded a mechanistic understanding of blastema formation. By tracing cells during digit tip regeneration using brainbow transgenic axolotls, we show that cells from each connective tissue compartment have distinct spatial and temporal profiles of proliferation, migration, and differentiation. Chondrocytes proliferate but do not migrate into the regenerate. In contrast, pericytes proliferate, then migrate into the blastema and give rise solely to pericytes. Periskeletal cells and fibroblasts contribute the bulk of digit blastema cells and acquire diverse fates according to successive waves of migration that choreograph their proximal-distal and tissue contributions. We further show that platelet-derived growth factor signaling is a potent inducer of fibroblast migration, which is required to form the blastema., Highlights • Distinct migratory and proliferative dynamics in axolotl connective tissue subtypes • Timing of dermal migration into the blastema biases contribution to skeleton or dermis • Participating source zone of 50–500 μm, depending on cell type and amputation site • PDGF-BB is a connective tissue pro-migratory signal necessary for blastema formation, Currie et al. use live imaging of brainbow transgenic axolotls to identify which connective tissues build the blastema for regeneration and the source zone from which they migrate. Each connective tissue cell type has highly characteristic migration kinetics that choreograph their fate and tissue contribution during regeneration.
- Published
- 2016
- Full Text
- View/download PDF
16. Draft genome of
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Yang, An, Akane, Kawaguchi, Chen, Zhao, Atsushi, Toyoda, Ali, Sharifi-Zarchi, Seyed Ahmad, Mousavi, Reza, Bagherzadeh, Takeshi, Inoue, Hajime, Ogino, Asao, Fujiyama, Hamidreza, Chitsaz, Hossein, Baharvand, and Kiyokazu, Agata
- Subjects
Planarian ,Dugesia japonica ,Genome ,Nou-darake ,Conserved non-coding elements ,Research Article - Abstract
Background Planarians are non-parasitic Platyhelminthes (flatworms) famous for their regeneration ability and for having a well-organized brain. Dugesia japonica is a typical planarian species that is widely distributed in the East Asia. Extensive cellular and molecular experimental methods have been developed to identify the functions of thousands of genes in this species, making this planarian a good experimental model for regeneration biology and neurobiology. However, no genome-level information is available for D. japonica, and few gene regulatory networks have been identified thus far. Results To obtain whole-genome information on this species and to study its gene regulatory networks, we extracted genomic DNA from 200 planarians derived from a laboratory-bred asexual clonal strain, and sequenced 476 Gb of data by second-generation sequencing. Kmer frequency graphing and fosmid sequence analysis indicated a complex genome that would be difficult to assemble using second-generation sequencing short reads. To address this challenge, we developed a new assembly strategy and improved the de novo genome assembly, producing a 1.56 Gb genome sequence (DjGenome ver1.0, including 202,925 scaffolds and N50 length 27,741 bp) that covers 99.4% of all 19,543 genes in the assembled transcriptome, although the genome is fragmented as 80% of the genome consists of repeated sequences (genomic frequency ≥ 2). By genome comparison between two planarian genera, we identified conserved non-coding elements (CNEs), which are indicative of gene regulatory elements. Transgenic experiments using Xenopus laevis indicated that one of the CNEs in the Djndk gene may be a regulatory element, suggesting that the regulation of the ndk gene and the brain formation mechanism may be conserved between vertebrates and invertebrates. Conclusion This draft genome and CNE analysis will contribute to resolving gene regulatory networks in planarians. The genome database is available at: http://www.planarian.jp. Electronic supplementary material The online version of this article (10.1186/s40851-018-0102-2) contains supplementary material, which is available to authorized users.
- Published
- 2018
17. Draft genome of Dugesia japonica provides insights into conserved regulatory elements of the brain restriction gene nou-darake in planarians
- Author
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Ali Sharifi-Zarchi, Seyed Ahmad Mousavi, Akane Kawaguchi, Hajime Ogino, Asao Fujiyama, Hossein Baharvand, Reza Bagherzadeh, Kiyokazu Agata, Takeshi Inoue, Hamidreza Chitsaz, Atsushi Toyoda, Yang An, and Chen Zhao
- Subjects
0301 basic medicine ,Whole genome sequencing ,Planarian ,Genome ,Sequence analysis ,Sequence assembly ,Computational biology ,Biology ,biology.organism_classification ,Fosmid ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,Dugesia japonica ,Nou-darake ,Conserved Non-coding Elements ,Dugesia Japonica ,lcsh:Zoology ,Animal Science and Zoology ,lcsh:QL1-991 ,Gene ,Conserved non-coding elements ,030217 neurology & neurosurgery - Abstract
Planarians are non-parasitic Platyhelminthes (flatworms) famous for their regeneration ability and for having a well-organized brain. Dugesia japonica is a typical planarian species that is widely distributed in the East Asia. Extensive cellular and molecular experimental methods have been developed to identify the functions of thousands of genes in this species, making this planarian a good experimental model for regeneration biology and neurobiology. However, no genome-level information is available for D. japonica, and few gene regulatory networks have been identified thus far. To obtain whole-genome information on this species and to study its gene regulatory networks, we extracted genomic DNA from 200 planarians derived from a laboratory-bred asexual clonal strain, and sequenced 476 Gb of data by second-generation sequencing. Kmer frequency graphing and fosmid sequence analysis indicated a complex genome that would be difficult to assemble using second-generation sequencing short reads. To address this challenge, we developed a new assembly strategy and improved the de novo genome assembly, producing a 1.56 Gb genome sequence (DjGenome ver1.0, including 202,925 scaffolds and N50 length 27,741 bp) that covers 99.4% of all 19,543 genes in the assembled transcriptome, although the genome is fragmented as 80% of the genome consists of repeated sequences (genomic frequency ≥ 2). By genome comparison between two planarian genera, we identified conserved non-coding elements (CNEs), which are indicative of gene regulatory elements. Transgenic experiments using Xenopus laevis indicated that one of the CNEs in the Djndk gene may be a regulatory element, suggesting that the regulation of the ndk gene and the brain formation mechanism may be conserved between vertebrates and invertebrates. This draft genome and CNE analysis will contribute to resolving gene regulatory networks in planarians. The genome database is available at: http://www.planarian.jp .
- Published
- 2018
18. Application of thecis-regulatory region of a heat-shock protein 70 gene to heat-inducible gene expression in the ascidianCiona intestinalis
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Aya Ohya, Maki Morita, Nanami Utsumi, Akane Kawaguchi, and Shuichi Wada
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Reporter gene ,animal structures ,Transgene ,Pair-rule gene ,Embryo ,Cell Biology ,Biology ,biology.organism_classification ,Molecular biology ,Hsp70 ,Endocrinology ,embryonic structures ,Gene expression ,Genetics ,Ciona intestinalis ,Gene - Abstract
Temporally controlled induction of gene expression is a useful technique for analyzing gene function. To make such a technique possible in Ciona intestinalis embryos, we employed the cis-regulatory region of the heat-shock protein 70 (HSP70) gene Ci-HSPA1/6/7-like for heat-inducible gene expression in C. intestinalis embryos. We showed that Ci-HSPA1/6/7-like becomes heat shock-inducible by the 32-cell stage during embryogenesis. The 5'-upstream region of Ci-HSPA1/6/7-like, which contains heat-shock elements indispensable for heat-inducible gene expression, induces the heat shock-dependent expression of a reporter gene in the whole embryo from the 32-cell to the middle gastrula stages and in progressively restricted areas of embryos in subsequent stages. We assessed the effects of heat-shock treatments in different conditions on the normality of embryos and induction of transgene expression. We evaluated the usefulness of this technique through overexpression experiments on the well-characterized, developmentally relevant gene, Ci-Bra, and showed that this technique is applicable for inferring the gene function in C. intestinalis.
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- 2014
19. Noncanonical Hox, Etv4, and Gli3 gene activities give insight into unique limb patterning in salamanders
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Igor Schneider, Gabriela N. Frota-Lima, Nadia B. Fröbisch, Sandra Karla Triepel, Constanze Bickelmann, and Akane Kawaguchi
- Subjects
0301 basic medicine ,Urodela ,03 medical and health sciences ,Axolotl ,Zinc Finger Protein Gli3 ,biology.animal ,Proto-Oncogene Proteins ,GLI3 ,Genetics ,Limb development ,Animals ,Cloning, Molecular ,Ambystoma mexicanum ,Hox gene ,Transcription factor ,Ecology, Evolution, Behavior and Systematics ,Phylogeny ,Body Patterning ,biology ,Genes, Homeobox ,Gene Expression Regulation, Developmental ,Extremities ,biology.organism_classification ,body regions ,030104 developmental biology ,HOXD13 ,Evolutionary biology ,Larva ,Molecular Medicine ,Salamander ,Animal Science and Zoology ,Developmental Biology - Abstract
Limb development in salamanders is unique among tetrapods in significant ways. Not only can salamanders regenerate lost limbs repeatedly and throughout their lives, but also the preaxial zeugopodial element and digits form before the postaxial ones and, hence, with a reversed polarity compared to all other tetrapods. Moreover, in salamanders with free-swimming larval stages, as exemplified by the axolotl (Ambystoma mexicanum), each digit buds independently, instead of undergoing a paddle stage. Here, we report gene expression patterns of Hoxa and d clusters, and other crucial transcription factors during axolotl limb development. During early phases of limb development, expression patterns are mostly similar to those reported for amniotes and frogs. Likewise, Hoxd and Shh regulatory landscapes are largely conserved. However, during late digit-budding phases, remarkable differences are present: (i) the Hoxd13 expression domain excludes developing digits I and IV, (ii) we expand upon previous observation that Hoxa11 expression, which traditionally marks the zeugopodium, extends distally into the developing digits, and (iii) Gli3 and Etv4 show prolonged expression in developing digits. Our findings identify derived patterns in the expression of key transcription factors during late phases of salamander limb development, and provide the basis for a better understanding of the unique patterning of salamander limbs.
- Published
- 2017
20. Asymmetrically reduced expression of hand1 homeologs involving a single nucleotide substitution in a cis-regulatory element
- Author
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Hajime Ogino, Haruki Ochi, Nanoka Suzuki, and Akane Kawaguchi
- Subjects
0301 basic medicine ,Embryo, Nonmammalian ,Sequence analysis ,Transgene ,Xenopus ,Regulatory Sequences, Nucleic Acid ,Genome ,Polymorphism, Single Nucleotide ,Synteny ,Animals, Genetically Modified ,03 medical and health sciences ,Negative selection ,0302 clinical medicine ,Genes, Reporter ,Sequence Homology, Nucleic Acid ,Gene expression ,Basic Helix-Loop-Helix Transcription Factors ,Animals ,Humans ,Amino Acid Sequence ,Promoter Regions, Genetic ,Molecular Biology ,Gene ,Conserved Sequence ,In Situ Hybridization ,Genetics ,biology ,Base Sequence ,Sequence Analysis, RNA ,myr ,Gene Expression Regulation, Developmental ,Cell Biology ,biology.organism_classification ,030104 developmental biology ,Enhancer Elements, Genetic ,030217 neurology & neurosurgery ,Developmental Biology - Abstract
During vertebrate evolution, whole genome duplications resulted in a number of duplicated genes, some of which eventually changed their expression patterns and/or levels via alteration of cis-regulatory sequences. However, the initial process involved in such cis-regulatory changes remains unclear. Therefore, we investigated this process by analyzing the duplicated hand1 genes of Xenopus laevis (hand1.L and hand1.S), which were generated by allotetraploidization 17–18 million years ago, and compared these with their single ortholog in the ancestral-type diploid species X. tropicalis. A dN/dS analysis indicated that hand1.L and hand1.S are still under purifying selection, and thus, their products appear to retain ancestral functional properties. RNA-seq and in situ hybridization analyses revealed that hand1.L and hand1.S have similar expression patterns to each other and to X. tropicalis hand1, but the hand1.S expression level was much lower than the hand1.L expression level in the primordial heart. A comparative sequence analysis, luciferase reporter analysis, ChIP-PCR analysis, and transgenic reporter analysis showed that a single nucleotide substitution in the hand1.S promoter was responsible for the reduced expression in the heart. These findings demonstrated that a small change in the promoter sequence can trigger diversification of duplicated gene expression prior to diversification of their encoded protein functions in a young duplicated genome.
- Published
- 2016
21. Application of the cis-regulatory region of a heat-shock protein 70 gene to heat-inducible gene expression in the ascidian Ciona intestinalis
- Author
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Akane, Kawaguchi, Nanami, Utsumi, Maki, Morita, Aya, Ohya, and Shuichi, Wada
- Subjects
Hot Temperature ,Genes, Reporter ,Animals ,Gene Expression Regulation, Developmental ,HSP70 Heat-Shock Proteins ,Regulatory Sequences, Nucleic Acid ,Heat-Shock Response ,Ciona intestinalis - Abstract
Temporally controlled induction of gene expression is a useful technique for analyzing gene function. To make such a technique possible in Ciona intestinalis embryos, we employed the cis-regulatory region of the heat-shock protein 70 (HSP70) gene Ci-HSPA1/6/7-like for heat-inducible gene expression in C. intestinalis embryos. We showed that Ci-HSPA1/6/7-like becomes heat shock-inducible by the 32-cell stage during embryogenesis. The 5'-upstream region of Ci-HSPA1/6/7-like, which contains heat-shock elements indispensable for heat-inducible gene expression, induces the heat shock-dependent expression of a reporter gene in the whole embryo from the 32-cell to the middle gastrula stages and in progressively restricted areas of embryos in subsequent stages. We assessed the effects of heat-shock treatments in different conditions on the normality of embryos and induction of transgene expression. We evaluated the usefulness of this technique through overexpression experiments on the well-characterized, developmentally relevant gene, Ci-Bra, and showed that this technique is applicable for inferring the gene function in C. intestinalis.
- Published
- 2014
22. Differential Use of Paralogous Genes via Evolution of Cis-Regulatory Elements for Divergent Expression Specificities
- Author
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Hajime Ogino, Haruki Ochi, and Akane Kawaguchi
- Subjects
Genetics ,biology ,biology.animal ,Nucleic acid sequence ,Vertebrate ,Chordate ,Paralogous Gene ,Silencer ,Enhancer ,biology.organism_classification ,Genome ,Gene - Abstract
Recent accumulation of genome sequences indicates that vertebrate genomes retained many duplicate genes, called paralogues, after whole-genome duplications (WGDs) occurring in the early stages of chordate evolution. Although paralogous gene pairs probably had the same expression patterns immediately after WGDs, they often showed distinct expression patterns in modern vertebrates. Nucleotide sequence changes in noncoding genomic regions, including cis-regulatory elements (CRE) such as enhancers and silencers, are the primary cause of the divergent paralogue expression. Such CRE evolution can be classified as follows: (1) enhancer innovation, (2) silencer innovation, and (3) ancestral CRE degeneration. In this chapter, we first show examples of the degeneration of ancestral CREs, with reference to the duplication–degeneration–complementation model, and subsequently introduce recently discovered evidence for silencer innovation and conservation of ancestral pleiotropic enhancers. Finally, we discuss the possible involvement of enhancer innovation in the divergent paralogue expression.
- Published
- 2014
23. Comparative expression analysis of the H3K27 demethylases, JMJD3 and UTX, with the H3K27 methylase, EZH2, in Xenopus
- Author
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Norihiro Sudou, Akane Kawaguchi, Hajime Ogino, and Haruki Ochi
- Subjects
Embryology ,Mesoderm ,Jumonji Domain-Containing Histone Demethylases ,animal structures ,Embryo, Nonmammalian ,Xenopus ,Green Fluorescent Proteins ,Molecular Sequence Data ,Ectoderm ,Biology ,Xenopus Proteins ,Methylation ,Histones ,Chlorocebus aethiops ,medicine ,Animals ,Amino Acid Sequence ,In Situ Hybridization ,Phylogeny ,Regulation of gene expression ,Genetics ,Microscopy, Confocal ,Sequence Homology, Amino Acid ,Reverse Transcriptase Polymerase Chain Reaction ,Lysine ,Gene Expression Regulation, Developmental ,Histone-Lysine N-Methyltransferase ,Blastula ,Cell biology ,Gastrulation ,medicine.anatomical_structure ,Neurula ,embryonic structures ,COS Cells ,Neural development ,Neural plate ,Developmental Biology - Abstract
The regulated removal of the gene-silencing epigenetic mark, trimethylation of lysine 27 of histone H3 (H3K27me3), has been shown to be critical for tissue-specific activation of developmental genes; however, the extent of embryonic expression of its demethylases, JMJD3 and UTX, has remained unclear. In this study, we investigated the expression of jmjd3 and utx genes in Xenopus embryos in parallel with that of the H3K27 methylase gene, ezh2. At the blastula stage, jmjd3, utx and ezh2 showed similar expression patterns in the animal cap and marginal zone that give rise to the ectoderm and mesoderm, respectively. The three genes maintained similar expression patterns in the neural plate, preplacodal ectoderm and axial mesoderm during the gastrula and neurula stages. Later, expression was maintained in the developing brain and cranial sensory tissues, such as the eye and ear, of tailbud embryos. These findings suggest that the H3K27 demethylases and methylase may function continuously for progressive switching of genetic programs during neural development, a model involving the simultaneous action of both of the demethylases for the de-repression of silent genes and the methylase for the silencing of active genes.
- Published
- 2012
24. Evolution of a tissue-specific silencer underlies divergence in the expression of pax2 and pax8 paralogues
- Author
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Haruki Ochi, Norihiro Sudou, Akane Kawaguchi, Hiroki Nagano, Hajime Ogino, and Tomoko Tamai
- Subjects
Genetics ,Multidisciplinary ,Xenopus ,PAX2 ,PAX2 Transcription Factor ,General Physics and Astronomy ,General Chemistry ,Biology ,Silencer ,General Biochemistry, Genetics and Molecular Biology ,Divergence ,Cell biology ,Animals, Genetically Modified ,Enhancer Elements, Genetic ,Expression (architecture) ,Gene duplication ,Vertebrates ,Tissue specific ,Animals ,Humans ,Paired Box Transcription Factors ,PAX8 ,Promoter Regions, Genetic ,Gene - Abstract
Recent studies underscore a role for the differential degeneration of enhancers in the evolutionary diversification of paralogue expression. However, no one has reported evidence for the involvement of innovative cis-regulatory changes. Here we show that silencer innovation diversified expression of the vertebrate paralogues, pax2 and pax8. pax2 shows multi-tissue expression, as does the ancestral amphioxus orthologue, pax2/5/8, whereas pax8 expression localizes to a subset of pax2-expressing tissues. We reveal that both pax2 and pax8 retain ancestral enhancers capable of directing pax2-like, multi-tissue expression. However, a silencer within the pax8 proximal promoter suppresses pleiotropic enhancer activity outside the pax8-expressing tissues. In contrast, the combination of the pax2 proximal promoter with either the pax8 or pax2 enhancer recapitulates pax2-like expression, as in the amphioxus pax2/5/8 promoter. We propose that silencer innovation, rather than enhancer degeneration, was crucial for the divergent expression of paralogues with pleiotropic enhancers inherited from their common progenitor.
- Published
- 2011
25. P34. Functional analysis of the histone H3K27 methyltransferase and demethylase in Xenopus embryonic development
- Author
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Hajime Ogino, Akane Kawaguchi, Makoto Okano, Norihiro Sudou, and Haruki Ochi
- Subjects
Cancer Research ,animal structures ,biology ,EZH2 ,Neural tube ,Neural crest ,Ectoderm ,Cell Biology ,Molecular biology ,Histone H3 ,medicine.anatomical_structure ,Neurula ,embryonic structures ,Histone methylation ,biology.protein ,medicine ,PRC2 ,Molecular Biology ,Developmental Biology - Abstract
Recent studies have revealed that epigenetic modifications, such as histone methylation, histone acetylation and DNA methylation, play fundamental roles in gene expression from the genome. Among them, the trimethylation/demethylation of histone H3 lysine 27 (H3K27) is associated with silencing/activation of some developmental regulatory genes, such as Hox clusters. In mammals, the trimethylation of H3K27 is mediated by the Polycomb repressive complex 2 (PRC2) that consists of three core subunits, Ezh2, Eed and Suz12 proteins, whereas the demethylation is mediated by Jmjd3 and Utx proteins. We isolated Xenopus orthologs of Ezh2, Eed, Jmjd3 and Utx, and examined their expression and function to explore roles for the H3K27 trimethylation/demethylation in frog development. Their expression all initially localizes in the animal hemisphere at the blastula stages, and subsequently remains faintly in the ectoderm at the gastrula stages. After the neural tube closure, expression of Ezh2, Eed, Jmjd3 and Utx becomes remarkable in the brain, eye, spinal cord, and migrating head neural crest cells. Overexpression of either Ezh2 or Jmjd3 perturbed expression of neural crest genes, Slug and Twist, but did not apparently affect gene expression in the central nervous system, such as Otx2 and Six3 in the forebrain and midbrain, Krox20 in the hindbrain, and HoxB9 in the spinal cord, at the neurula stages. Alcian blue staining revealed that these over-expressed embryos later developed abnormal cranial cartilage structures at the tadpole stages. These results showed that both the genes for trimethylation and demethylation of H3K27 are co-expressed in the neural tissues, and suggests that the regulated balance between these two activities is critical for the neural crest development.
- Published
- 2010
26. P33. Evolution of a fail-safe regulatory system for kidney development
- Author
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Haruki Ochi, Chihiro Uchiyama, Akane Kawaguchi, and Hajime Ogino
- Subjects
Genetics ,Regulation of gene expression ,Cancer Research ,animal structures ,urogenital system ,Xenopus ,Cell Biology ,Paralogous Gene ,Biology ,biology.organism_classification ,Genome ,Pronephros ,hemic and lymphatic diseases ,embryonic structures ,Gene duplication ,sense organs ,Enhancer ,Molecular Biology ,Gene ,Developmental Biology - Abstract
During the chordate evolution, genome duplications have produced a number of paralogous gene pairs. While genetic studies often discover functional compensation between paralog genes, little is known about regulatory mechanisms underlying their interactions. In this study we addressed this issue by studying regulation of vertebrate Pax2, Pax5 and Pax8 genes that have evolved from a single ancestral gene of early cephalochordates and exhibit overlapping but different expression during eye, ear, brain and kidney development. Comparison of human, chicken and Xenopus genomic sequences in the Pax2/5/8 loci and high-throughput transgenic analysis in Xenopus identified 16 enhancers for Pax2, 7 for Pax5, and 3 for Pax8. Interestingly, Pax5 and Pax8 are associated with enhancers that are active in the tissues expressing Pax2, but not Pax5 or Pax8. One of such Pax5 enhancers, which is active in the pronephros, shares sequence features with a Pax2 pronephric enhancer. These two appear to have evolved from the common ancestral enhancer through the genome duplication. This Pax5 enhancer implied a hidden potential of this gene to be activated in the pronephros, and we actually found that Pax2-knockdowned embryos express Pax5 in the pronephros to rescue expression of WT1, a downstream target of Pax2 in normal embryos. These results revealed a dynamic balancing mechanism between the paralogs, which involves ectopic gene activation and may reflect regulatory mechanisms of their ancestral gene.
- Published
- 2010
27. OBSERVATION OF STRATOSPHERIC NO_2 AT SYOWA STATION, ANTARCTICA
- Author
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Akane, KAWAGUCHI, Yutaka, KONDO, Makoto, KOIKE, Hideaki, NAKAJIMA, Shuhji, AOKI, Takashi, YAMANOUCHI, Michihiro, KOIDE, Ippei, NAGAO, Kunimoto, IWAI, ABSTRACT, Solar Terrestrial Environment Laboratory, Nagoya University, Faculty of Science, Tohoku University, National Institute of Polar Research, Institute for Hydrospheric-Atmospheric Sciences, Nagoya University, and Faculty of Education, Shinsyu University
- Abstract
Ground based observations of NO_2 and O_3 using visible spectrometers have been made at Syowa Station (69°S) since March 1990. The NO_2 slant column amounts observed at the solar zenith angle of 90°(sunrise and sunset) exhibit a large seasonal variation, decreasing with shortening daylight hours in fall, reaching a minimum of about 1×(10)^(cm)^ in midwinter and increasing to a maximum of about 16×(10)^(cm)^ in midsummer. The recovery of NO_2 in spring is 2-3 times slower than the fall decay, because the heterogeneous chemistry on PSCs, the conversion of NO_x into HNO_3,is effective from midwinter to early spring, and NO_y is removed from the stratosphere through gravitational sedimentation of PSCs particles. In late spring the PSCs decrease and NO_2 increases because of the transport of air from lower latitudes. Following the eruption of Mt. Pinatubo (15°N) in June 1991,the NO_2 amounts in midsummer of 1991 were lower by 20-30% than those in 1990. The NO_2 amount in midsummer increased year after year and recovered to the 1990 level by 1994. The NO_2 amount in fall also recovered since 1992; however, the rate of recovery is smaller than in summer. The NO_2 level in fall of 1993 was as low as those in 1992. On the other hand, the rate of recovery in the box model using the observed aerosol surface areas by SAGE (S. SOLOMON et al., J. Geophys. Res., 99,3509,1994) is larger than that observed at McMurdo and Syowa Stations. This may suggest that another factor delays the NO_2 recovery in fall. NO_2 levels in winter have a positive correlation with temperature at 20 and 70 hPa (about 25 and 18km, respectively). In colder winters such as 1990 and 1993,the NO_2 levels were lower than those in other years. This may be due to the difference in the location of the polar vortex boundary relative to Syowa Station. The NO_2 amount and the temperature are considered to be lower deep inside the vortex as compared to near the boundary. In spring, the NO_2 and O_3 amounts and the temperature largely change when the vortex boundary crosses over Syowa Station. The vortex boundary can be clearly seen in the total O_3 maps obtained by TOMS. The monthly mean O_3 values suggest that Syowa Station was located deep inside of the vortex in October 1992 when the NO_2 level was lower than in other years. In contrast, Syowa Station was located near the edge of the vortex in October 1991 when the NO_2 level was much higher.
- Published
- 1996
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