1
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Endo Y, Yan X, Li M, Akiyama R, Brandl C, Liu JZ, Hobara R, Hasegawa S, Wan W, Novoselov KS, Tang WX. Dynamic topological domain walls driven by lithium intercalation in graphene. Nat Nanotechnol 2023; 18:1154-1161. [PMID: 37488219 DOI: 10.1038/s41565-023-01463-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 06/20/2023] [Indexed: 07/26/2023]
Abstract
Stacking engineering in van der Waals (vdW) materials is a powerful method to control topological electronic phases for quantum device applications. Atomic intercalation into the vdW material can modulate the stacking structure at the atomic scale without a highly technical protocol. Here we report that lithium intercalation in a topologically structured graphene/buffer system on SiC(0001) drives dynamic topological domain wall (TDW) motions associated with stacking order change by using an in situ aberration-corrected low-energy electron microscope in combination with theoretical modelling. We observe sequential and selective lithium intercalation that starts at topological crossing points (AA stacking) and then selectively extends to AB stacking domains. Lithium intercalation locally changes the domain stacking order to AA and in turn alters the neighbouring TDW stacking orders, and continuous intercalation drives the evolution of the whole topological structure network. Our work reveals moving TDWs protected by the topology of stacking and lays the foundation for controlling the stacking structure via atomic intercalation. These findings open up new avenues to realize intercalation-driven vdW electronic devices.
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Affiliation(s)
- Yukihiro Endo
- Department of Physics, The University of Tokyo, Tokyo, Japan
| | - Xue Yan
- Department of Mechanical Engineering, The University of Melbourne, Parkville, Victoria, Australia
| | - Meng Li
- College of Materials Science and Engineering, Chongqing University, Chongqing, China.
| | - Ryota Akiyama
- Department of Physics, The University of Tokyo, Tokyo, Japan.
| | - Christian Brandl
- Department of Mechanical Engineering, The University of Melbourne, Parkville, Victoria, Australia
| | - Jefferson Zhe Liu
- Department of Mechanical Engineering, The University of Melbourne, Parkville, Victoria, Australia.
| | - Rei Hobara
- Department of Physics, The University of Tokyo, Tokyo, Japan
| | - Shuji Hasegawa
- Department of Physics, The University of Tokyo, Tokyo, Japan
| | - Weishi Wan
- ShanghaiTech University, Shanghai, China
| | - K S Novoselov
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore
| | - Wen-Xin Tang
- College of Materials Science and Engineering, Chongqing University, Chongqing, China.
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2
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Umemoto N, Yasumoto S, Yamazaki M, Asano K, Akai K, Lee HJ, Akiyama R, Mizutani M, Nagira Y, Saito K, Muranaka T. Integrated gene-free potato genome editing using transient transcription activator-like effector nucleases and regeneration-promoting gene expression by Agrobacterium infection. Plant Biotechnol (Tokyo) 2023; 40:211-218. [PMID: 38420569 PMCID: PMC10901161 DOI: 10.5511/plantbiotechnology.23.0530a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 05/30/2023] [Indexed: 03/02/2024]
Abstract
Genome editing is highly useful for crop improvement. The method of expressing genome-editing enzymes using a transient expression system in Agrobacterium, called agrobacterial mutagenesis, is a shortcut used in genome-editing technology to improve elite varieties of vegetatively propagated crops, including potato. However, with this method, edited individuals cannot be selected. The transient expression of regeneration-promoting genes can result in shoot regeneration from plantlets, while the constitutive expression of most regeneration-promoting genes does not result in normally regenerated shoots. Here, we report that we could obtain genome-edited potatoes by positive selection. These regenerated shoots were obtained via a method that combined a regeneration-promoting gene with the transient expression of a genome-editing enzyme gene. Moreover, we confirmed that the genome-edited potatoes obtained using this method did not contain the sequence of the binary vector used in Agrobacterium. Our data have been submitted to the Japanese regulatory authority, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), and we are in the process of conducting field tests for further research on these potatoes. Our work presents a powerful method for regarding regeneration and acquisition of genome-edited crops through transient expression of regeneration-promoting gene.
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Affiliation(s)
- Naoyuki Umemoto
- RIKEN Center for Sustainable Resource Science, Kanagawa 230-0045, Japan
| | - Shuhei Yasumoto
- Graduate School of Engineering, Osaka University, Osaka 565-0871, Japan
| | - Muneo Yamazaki
- National Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Ibaraki 305-8518, Japan
| | - Kenji Asano
- National Agricultural Research Center for Hokkaido Region, National Agriculture and Food Research Organization, Hokkaido 082-0081, Japan
| | - Kotaro Akai
- National Agricultural Research Center for Hokkaido Region, National Agriculture and Food Research Organization, Hokkaido 082-0081, Japan
| | - Hyoung Jae Lee
- Graduate School of Agricultural Science, Kobe University, Hyogo 657-8501, Japan
| | - Ryota Akiyama
- Graduate School of Agricultural Science, Kobe University, Hyogo 657-8501, Japan
| | - Masaharu Mizutani
- Graduate School of Agricultural Science, Kobe University, Hyogo 657-8501, Japan
| | - Yozo Nagira
- Agri-Bio Research Center, Kaneka Co., Shizuoka 438-0802, Japan
| | - Kazuki Saito
- RIKEN Center for Sustainable Resource Science, Kanagawa 230-0045, Japan
| | - Toshiya Muranaka
- Graduate School of Engineering, Osaka University, Osaka 565-0871, Japan
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3
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Akiyama R, Umemoto N, Mizutani M. Recent advances in steroidal glycoalkaloid biosynthesis in the genus Solanum. Plant Biotechnol (Tokyo) 2023; 40:185-191. [PMID: 38293253 PMCID: PMC10824493 DOI: 10.5511/plantbiotechnology.23.0717b] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Accepted: 07/17/2023] [Indexed: 02/01/2024]
Abstract
Steroidal glycoalkaloids (SGAs) are specialized metabolites found in members of Solanum species, and are also known as toxic substances in Solanum food crops such as tomato (Solanum lycopersicum), potato (Solanum tuberosum), and eggplant (Solanum melongena). SGA biosynthesis can be divided into two main parts: formation of steroidal aglycones, which are derived from cholesterol, and glycosylation at the C-3 hydroxy group. This review focuses on recent studies that shed light on the complete process of the aglycone formation in SGA biosynthesis and structural diversification of SGAs by duplicated dioxygenases, as well as the development of non-toxic potatoes through genome editing using these findings.
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Affiliation(s)
- Ryota Akiyama
- Graduate School of Agricultural Science, Kobe University, Hyogo 657-8501, Japan
| | - Naoyuki Umemoto
- RIKEN Center for Sustainable Resource Science, Kanagawa 230-0045, Japan
| | - Masaharu Mizutani
- Graduate School of Agricultural Science, Kobe University, Hyogo 657-8501, Japan
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4
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Kobayashi T, Toichi Y, Yaji K, Nakata Y, Yaoita Y, Iwaoka M, Koga M, Zhang Y, Fujii J, Ono S, Sassa Y, Yoshida Y, Hasegawa Y, Komori F, Shin S, Ichinokura S, Akiyama R, Hasegawa S, Shishidou T, Weinert M, Sakamoto K. Revealing the Hidden Spin-Polarized Bands in a Superconducting Tl Bilayer Crystal. Nano Lett 2023; 23:7675-7682. [PMID: 37578323 PMCID: PMC10450804 DOI: 10.1021/acs.nanolett.3c02387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 08/04/2023] [Indexed: 08/15/2023]
Abstract
The interplay of spin-orbit coupling and crystal symmetry can generate spin-polarized bands in materials only a few atomic layers thick, potentially leading to unprecedented physical properties. In the case of bilayer materials with global inversion symmetry, locally broken inversion symmetry can generate degenerate spin-polarized bands, in which the spins in each layer are oppositely polarized. Here, we demonstrate that the hidden spins in a Tl bilayer crystal are revealed by growing it on Ag(111) of sizable lattice mismatch, together with the appearance of a remarkable phenomenon unique to centrosymmetric hidden-spin bilayer crystals: a novel band splitting in both spin and space. The key to success in observing this novel splitting is that the interaction at the interface has just the right strength: it does not destroy the original wave functions of the Tl bilayer but is strong enough to induce an energy separation.
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Affiliation(s)
- Takahiro Kobayashi
- Department
of Material and Life Science, Osaka University, Osaka 565-0871, Japan
| | - Yuichiro Toichi
- Department
of Applied Physics, Osaka University, Osaka 565-0871, Japan
| | - Koichiro Yaji
- Research
Center for Advanced Measurement and Characterization, National Institute for Materials Science, Ibaraki 305-0047, Japan
| | - Yoshitaka Nakata
- Department
of Materials Science, Chiba University, Chiba 263-8522, Japan
| | - Yuchi Yaoita
- Department
of Materials Science, Chiba University, Chiba 263-8522, Japan
| | - Mutsuki Iwaoka
- Department
of Materials Science, Chiba University, Chiba 263-8522, Japan
| | - Mariko Koga
- Department
of Materials Science, Chiba University, Chiba 263-8522, Japan
| | - Yituo Zhang
- Department
of Materials Science, Chiba University, Chiba 263-8522, Japan
| | - Jun Fujii
- Istituto
Officina dei Materiali, Consiglio Nazionale
delle Ricerche (CNR-IOM), I-34149 Trieste, Italy
| | - Shimpei Ono
- Central
Research institute of Electric Power Industry, Yokosuka 240-0196, Japan
| | - Yasmine Sassa
- Department
of Physics, Chalmers University of Technology, Göteborg 412 96, Sweden
| | - Yasuo Yoshida
- Institute
for Solid State Physics, The University
of Tokyo, Chiba 277-8581, Japan
| | - Yukio Hasegawa
- Institute
for Solid State Physics, The University
of Tokyo, Chiba 277-8581, Japan
| | - Fumio Komori
- Institute
for Solid State Physics, The University
of Tokyo, Chiba 277-8581, Japan
| | - Shik Shin
- Institute
for Solid State Physics, The University
of Tokyo, Chiba 277-8581, Japan
| | - Satoru Ichinokura
- Department
of Physics, The University of Tokyo, Tokyo 113-0033, Japan
| | - Ryota Akiyama
- Department
of Physics, The University of Tokyo, Tokyo 113-0033, Japan
| | - Shuji Hasegawa
- Department
of Physics, The University of Tokyo, Tokyo 113-0033, Japan
| | - Tatsuya Shishidou
- Department
of Physics, University of Wisconsin, Milwaukee, Wisconsin 53201, United States
| | - Michael Weinert
- Department
of Physics, University of Wisconsin, Milwaukee, Wisconsin 53201, United States
| | - Kazuyuki Sakamoto
- Department
of Applied Physics, Osaka University, Osaka 565-0871, Japan
- Spintronics
Research Network Division, Institute for Open and Transdisciplinary
Research Initiatives, Osaka University, Osaka 565-0871, Japan
- Center
for Spintronics Research Network, Osaka
University, Osaka 560-8531, Japan
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5
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Hatada M, Akiyama R, Yamagishi M, Ishizaki K, Mizutani M. MpDWF5A-encoded sterol Δ7-reductase is essential for the normal growth and development of Marchantia polymorpha. Plant Cell Physiol 2023:7161702. [PMID: 37178336 DOI: 10.1093/pcp/pcad043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 04/20/2023] [Accepted: 05/10/2023] [Indexed: 05/15/2023]
Abstract
Sterols are the essential components of the eukaryotic cell membranes. However, studies on sterol biosynthesis in bryophytes are limited. This study analyzed the sterol profiles in the bryophyte model plant Marchantia polymorpha L. The thalli contained typical phytosterols such as campesterol, sitosterol, and stigmasterol. BLASTX analysis of the M. polymorpha genome against the Arabidopsis thaliana sterol biosynthetic genes confirmed the presence of all of the enzymes responsible for sterol biosynthesis in M. polymorpha. In this study, we focused on characterizing two genes, MpDWF5A and MpDWF5B, which showed high homology with A. thaliana DWF5, encoding Δ5,Δ7-sterol Δ7-reductase. Functional analysis using a yeast expression system revealed that MpDWF5A converted 7-dehydrocholesterol to cholesterol, indicating that MpDWF5A is a Δ5,Δ7-sterol Δ7-reductase. Mpdwf5a-knockout lines (Mpdwf5a-ko) were constructed using CRISPR/Cas9 mediated genome editing. GC-MS analysis of Mpdwf5a-ko revealed that phytosterols such as campesterol, sitosterol, and stigmasterol disappeared, and instead, the corresponding Δ7-type sterols accumulated. The thalli of Mpdwf5a-ko grew smaller than those of the wild type, and excessive formation of apical meristem in the thalli was observed. In addition, the gemma cups of the Mpdwf5a-ko were incomplete, and only a limited number of gemma formations were observed. Treatment with 1 µM of castesterone or 6-deoxocastasterone, a bioactive brassinosteroid, partly restored some of these abnormal phenotypes, but far from complete recovery. These results indicate that MpDWF5A is essential for the normal growth and development of M. polymorpha and suggest that the dwarfism caused by the MpDWF5A defect is due to the deficiency of typical phytosterols and, in part, a brassinosteroid-like compound derived from phytosterols.
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Affiliation(s)
- Miki Hatada
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Ryota Akiyama
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Moeko Yamagishi
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Kimitsune Ishizaki
- Graduate School of Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Masaharu Mizutani
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
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6
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Shimizu K, Akiyama R, Okamura Y, Ogawa C, Masuda Y, Sakata I, Watanabe B, Sugimoto Y, Kushida A, Tanino K, Mizutani M. Solanoeclepin B, a hatching factor for potato cyst nematode. Sci Adv 2023; 9:eadf4166. [PMID: 36921046 PMCID: PMC10017031 DOI: 10.1126/sciadv.adf4166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 02/09/2023] [Indexed: 06/18/2023]
Abstract
The potato cyst nematode (PCN) causes extensive crop losses worldwide. Because the hatching of PCN requires host-derived molecules known as hatching factors (HFs), regulating HF production in host plants may help to control this harmful pest. Solanoeclepin A (SEA), isolated from potato, is the most active HF for PCN; however, its biosynthesis is completely unknown. We discovered a HF called solanoeclepin B (SEB) from potato and tomato root exudates and showed that SEB was biosynthesized in the plant and converted to SEA outside the plant by biotic agents. Moreover, we identified five SEB biosynthetic genes encoding three 2-oxoglutarate-dependent dioxygenases and two cytochrome P450 monooxygenases in tomato. Exudates from tomato hairy roots in which each of the genes was disrupted contained no SEB and had low hatch-stimulating activity for PCN. These findings will help to breed crops with a lower risk of PCN infection.
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Affiliation(s)
- Kosuke Shimizu
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada, Kobe, Hyogo 657-8501, Japan
| | - Ryota Akiyama
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada, Kobe, Hyogo 657-8501, Japan
| | - Yuya Okamura
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada, Kobe, Hyogo 657-8501, Japan
| | - Chihiro Ogawa
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada, Kobe, Hyogo 657-8501, Japan
| | - Yuki Masuda
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada, Kobe, Hyogo 657-8501, Japan
| | - Itaru Sakata
- Technology Application Research Team, Department of Research Promotion, Hokkaido Agricultural Research Center, NARO, 1 Hitsujigaoka, Toyohira, Sapporo, Hokkaido 062-8555, Japan
| | - Bunta Watanabe
- The Jikei University School of Medicine, 8-3-1 Kokuryo, Chohu, Tokyo 182-8570, Japan
| | - Yukihiro Sugimoto
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada, Kobe, Hyogo 657-8501, Japan
| | - Atsuhiko Kushida
- Technology Application Research Team, Department of Research Promotion, Hokkaido Agricultural Research Center, NARO, 1 Hitsujigaoka, Toyohira, Sapporo, Hokkaido 062-8555, Japan
| | - Keiji Tanino
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
| | - Masaharu Mizutani
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada, Kobe, Hyogo 657-8501, Japan
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7
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Imura Y, Tanaka M, Kasuga A, Akiyama R, Ogawa D, Sugimori H, Morita-Imura C, Kawai T. Nanoarchitectonics and Catalytic Performance of Au-Pd Nanoflowers Supported on Fe 2O 3. J Oleo Sci 2023; 72:1055-1061. [PMID: 37914267 DOI: 10.5650/jos.ess23125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2023] Open
Abstract
Supported anisotropic bimetallic nanocrystals are attractive owing to their potential for novel catalytic applications. Au-Pd nanocrystals are expected to have higher catalytic activity for alcohol oxidation than Au nanocrystals. However, only a few studies have reported the application of anisotropic Au-Pd nanocrystals as alcohol-oxidation nanocatalysts. Support materials such as Al2O3 and Fe2O3 influence the catalytic activity of spherical Au nanoparticles. Thus, optimization of the support is expected to improve the catalytic activity of anisotropic Au-Pd nanocrystals. Herein, we report the synthesis and catalytic performances of Al2O3- and Fe2O3-supported Au and Au-Pd nanoflowers. Au99-Pd1 NFs supported on Fe2O3 exhibited the highest catalytic activity for 1-phenylethyl alcohol oxidation.
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Affiliation(s)
- Yoshiro Imura
- Department of Industrial Chemistry, Faculty of Engineering, Tokyo University of Science
| | - Masami Tanaka
- Department of Industrial Chemistry, Faculty of Engineering, Tokyo University of Science
| | - Asuka Kasuga
- Department of Industrial Chemistry, Faculty of Engineering, Tokyo University of Science
| | - Ryota Akiyama
- Department of Industrial Chemistry, Faculty of Engineering, Tokyo University of Science
| | - Daisuke Ogawa
- Technology Support Department, Tokyo Metropolitan Industrial Technology Research Institute
| | - Hirokazu Sugimori
- Technology Support Department, Tokyo Metropolitan Industrial Technology Research Institute
| | | | - Takeshi Kawai
- Department of Industrial Chemistry, Faculty of Engineering, Tokyo University of Science
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8
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Akiyama R, Ishikawa R, Akutsu-Suyama K, Nakanishi R, Tomohiro Y, Watanabe K, Iida K, Mitome M, Hasegawa S, Kuroda S. Direct Probe of the Ferromagnetic Proximity Effect at the Interface of SnTe/Fe Heterostructure by Polarized Neutron Reflectometry. J Phys Chem Lett 2022; 13:8228-8235. [PMID: 36031713 DOI: 10.1021/acs.jpclett.2c01478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Introducing magnetic order into a topological insulator (TI) system has attracted much attention with an expectation of realizing exotic phenomena such as the quantum anomalous Hall effect (QAHE) and axion insulator states. The magnetic proximity effect (MPE) is one of the promising schemes to induce the magnetic order on the surface of a TI without introducing disorder accompanied by doping magnetic impurities in the TI. In this study, we investigate the MPE at the interface of a heterostructure consisting of the topological crystalline insulator (TCI) SnTe and Fe by employing polarized neutron reflectometry. The ferromagnetic order penetrates ∼2.2 nm deep into the SnTe layer from the interface with Fe, which persists up to room temperature. This is induced by the MPE on the surface of the TCI preserving the coherent topological states without introducing the disorder by doping magnetic impurities. This would open up a way for realizing next-generation spintronics and quantum computational devices.
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Affiliation(s)
- Ryota Akiyama
- Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Ryo Ishikawa
- Institute of Materials Science, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8573, Japan
| | - Kazuhiro Akutsu-Suyama
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Ryosuke Nakanishi
- Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yuta Tomohiro
- Institute of Materials Science, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8573, Japan
| | - Kazumi Watanabe
- Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Kazuki Iida
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), 162-1 Shirakata, Tokai, Ibaraki 319-1106, Japan
| | - Masanori Mitome
- Electron Microscopy Analysis Station, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Shuji Hasegawa
- Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Shinji Kuroda
- Institute of Materials Science, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8573, Japan
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9
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Akiyama R, Watanabe B, Kato J, Nakayasu M, Lee HJ, Umemoto N, Muranaka T, Saito K, Sugimoto Y, Mizutani M. Tandem Gene Duplication of Dioxygenases Drives the Structural Diversity of Steroidal Glycoalkaloids in the Tomato Clade. Plant Cell Physiol 2022; 63:981-990. [PMID: 35560060 DOI: 10.1093/pcp/pcac064] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 04/05/2022] [Accepted: 05/12/2022] [Indexed: 06/15/2023]
Abstract
Cultivated tomato (Solanum lycopersicum) contains α-tomatine, a steroidal glycoalkaloid (SGA), which functions as a defense compound to protect against pathogens and herbivores; interestingly, wild species in the tomato clade biosynthesize a variety of SGAs. In cultivated tomato, the metabolic detoxification of α-tomatine during tomato fruit ripening is an important trait that aided in its domestication, and two distinct 2-oxoglutarate-dependent dioxygenases (DOXs), a C-23 hydroxylase of α-tomatine (Sl23DOX) and a C-27 hydroxylase of lycoperoside C (Sl27DOX), are key to this process. There are tandemly duplicated DOX genes on tomato chromosome 1, with high levels of similarity to Sl23DOX. While these DOX genes are rarely expressed in cultivated tomato tissues, the recombinant enzymes of Solyc01g006580 and Solyc01g006610 metabolized α-tomatine to habrochaitoside A and (20R)-20-hydroxytomatine and were therefore named as habrochaitoside A synthase (HAS) and α-tomatine 20-hydroxylase (20DOX), respectively. Furthermore, 20DOX and HAS exist in the genome of wild tomato S. habrochaites accession LA1777, which accumulates habrochaitoside A in its fruits, and their expression patterns were in agreement with the SGA profiles in LA1777. These results indicate that the functional divergence of α-tomatine-metabolizing DOX enzymes results from gene duplication and the neofunctionalization of catalytic activity and gene expression, and this contributes to the structural diversity of SGAs in the tomato clade.
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Affiliation(s)
- Ryota Akiyama
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada, Kobe, Hyogo, 657-8501 Japan
| | - Bunta Watanabe
- Institute for Chemical Research, Kyoto University, Gokasyo, Uji, Kyoto, 611-0011 Japan
| | - Junpei Kato
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada, Kobe, Hyogo, 657-8501 Japan
| | - Masaru Nakayasu
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada, Kobe, Hyogo, 657-8501 Japan
| | - Hyoung Jae Lee
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada, Kobe, Hyogo, 657-8501 Japan
| | - Naoyuki Umemoto
- RIKEN Center for Sustainable Resource Science, Suehiro-cho 1-7-22, Tsurumi-ku, Yokohama, Kanagawa, 230-0045 Japan
| | - Toshiya Muranaka
- Department of Biotechnology, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka, 565-0871 Japan
| | - Kazuki Saito
- RIKEN Center for Sustainable Resource Science, Suehiro-cho 1-7-22, Tsurumi-ku, Yokohama, Kanagawa, 230-0045 Japan
- Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba, 260-8675 Japan
| | - Yukihiro Sugimoto
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada, Kobe, Hyogo, 657-8501 Japan
| | - Masaharu Mizutani
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada, Kobe, Hyogo, 657-8501 Japan
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10
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Toyama H, Akiyama R, Ichinokura S, Hashizume M, Iimori T, Endo Y, Hobara R, Matsui T, Horii K, Sato S, Hirahara T, Komori F, Hasegawa S. Two-Dimensional Superconductivity of Ca-Intercalated Graphene on SiC: Vital Role of the Interface between Monolayer Graphene and the Substrate. ACS Nano 2022; 16:3582-3592. [PMID: 35209713 DOI: 10.1021/acsnano.1c11161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Ca-intercalation has enabled superconductivity in graphene on SiC. However, the atomic and electronic structures that are critical for superconductivity are still under discussion. We find an essential role of the interface between monolayer graphene and the SiC substrate for superconductivity. In the Ca-intercalation process, at the interface a carbon layer terminating SiC changes to graphene by Ca-termination of SiC (monolayer graphene becomes a bilayer), inducing more electrons than a free-standing model. Then, Ca is intercalated in between the graphene layers, which shows superconductivity with the updated critical temperature (TC) of up to 5.7 K. In addition, the relation between TC and the normal-state conductivity is unusual, "dome-shaped". These findings are beyond the simple C6CaC6 model in which s-wave BCS superconductivity is theoretically predicted. This work proposes a general picture of the intercalation-induced superconductivity in graphene on SiC and indicates the potential for superconductivity induced by other intercalants.
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Affiliation(s)
- Haruko Toyama
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Ryota Akiyama
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Satoru Ichinokura
- Department of Physics, Tokyo Institution of Technology, Meguro, Tokyo 152-8551, Japan
| | - Mizuki Hashizume
- Department of Physics, Tokyo Institution of Technology, Meguro, Tokyo 152-8551, Japan
| | - Takushi Iimori
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Yukihiro Endo
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Rei Hobara
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Tomohiro Matsui
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Kentaro Horii
- Department of Physics, Tokyo Institution of Technology, Meguro, Tokyo 152-8551, Japan
| | - Shunsuke Sato
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Toru Hirahara
- Department of Physics, Tokyo Institution of Technology, Meguro, Tokyo 152-8551, Japan
| | - Fumio Komori
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
| | - Shuji Hasegawa
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
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11
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Takashiro T, Akiyama R, Kibirev IA, Matetskiy AV, Nakanishi R, Sato S, Fukasawa T, Sasaki T, Toyama H, Hiwatari KL, Zotov AV, Saranin AA, Hirahara T, Hasegawa S. Soft-Magnetic Skyrmions Induced by Surface-State Coupling in an Intrinsic Ferromagnetic Topological Insulator Sandwich Structure. Nano Lett 2022; 22:881-887. [PMID: 35084202 DOI: 10.1021/acs.nanolett.1c02952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A magnetic skyrmion induced on a ferromagnetic topological insulator (TI) is a real-space manifestation of the chiral spin texture in the momentum space and can be a carrier for information processing by manipulating it in tailored structures. Here, a sandwich structure containing two layers of a self-assembled ferromagnetic septuple-layer TI, Mn(Bi1-xSbx)2Te4 (MnBST), separated by quintuple layers of TI, (Bi1-xSbx)2Te3 (BST), is fabricated and skyrmions are observed through the topological Hall effect in an intrinsic magnetic topological insulator for the first time. The thickness of BST spacer layer is crucial in controlling the coupling between the gapped topological surface states in the two MnBST layers to stabilize the skyrmion formation. The homogeneous, highly ordered arrangement of the Mn atoms in the septuple-layer MnBST leads to a strong exchange interaction therein, which makes the skyrmions "soft magnetic". This would open an avenue toward a topologically robust rewritable magnetic memory.
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Affiliation(s)
- Takuya Takashiro
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Ryota Akiyama
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Ivan A Kibirev
- Institute of Automation and Control Processes, Vladivostok 690041, Russia
| | - Andrey V Matetskiy
- Institute of Automation and Control Processes, Vladivostok 690041, Russia
| | - Ryosuke Nakanishi
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Shunsuke Sato
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Takuro Fukasawa
- Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Taisuke Sasaki
- National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
| | - Haruko Toyama
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Kota L Hiwatari
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
| | - Andrey V Zotov
- Institute of Automation and Control Processes, Vladivostok 690041, Russia
| | | | - Toru Hirahara
- Department of Physics, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Shuji Hasegawa
- Department of Physics, The University of Tokyo, Bunkyo, Tokyo 113-0033, Japan
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12
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Akiyama R, Nakayasu M, Umemoto N, Kato J, Kobayashi M, Lee HJ, Sugimoto Y, Iijima Y, Saito K, Muranaka T, Mizutani M. Tomato E8 Encodes a C-27 Hydroxylase in Metabolic Detoxification of α-Tomatine during Fruit Ripening. Plant Cell Physiol 2021; 62:775-783. [PMID: 34100555 DOI: 10.1093/pcp/pcab080] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/14/2021] [Accepted: 06/07/2021] [Indexed: 06/12/2023]
Abstract
Tomato (Solanum lycopersicum) contains α-tomatine, a steroidal glycoalkaloid that contributes to the plant defense against pathogens and herbivores through its bitter taste and toxicity. It accumulates at high levels in all the plant tissues, especially in leaves and immature green fruits, whereas it decreases during fruit ripening through metabolic conversion to the nontoxic esculeoside A, which accumulates in the mature red fruit. This study aimed to identify the gene encoding a C-27 hydroxylase that is a key enzyme in the metabolic conversion of α-tomatine to esculeoside A. The E8 gene, encoding a 2-oxoglutalate-dependent dioxygenase, is well known as an inducible gene in response to ethylene during fruit ripening. The recombinant E8 was found to catalyze the C-27 hydroxylation of lycoperoside C to produce prosapogenin A and is designated as Sl27DOX. The ripe fruit of E8/Sl27DOX-silenced transgenic tomato plants accumulated lycoperoside C and exhibited decreased esculeoside A levels compared with the wild-type (WT) plants. Furthermore, E8/Sl27DOX deletion in tomato accessions resulted in higher lycoperoside C levels in ripe fruits than in WT plants. Thus, E8/Sl27DOX functions as a C-27 hydroxylase of lycoperoside C in the metabolic detoxification of α-tomatine during tomato fruit ripening, and the efficient detoxification by E8/27DOX may provide an advantage in the domestication of cultivated tomatoes.
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Affiliation(s)
- Ryota Akiyama
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
| | - Masaru Nakayasu
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
- Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji, Kyoto, 611-0011 Japan
| | - Naoyuki Umemoto
- Department of Nutrition and Life Science, Kanagawa Institute of Technology, 1030 Shimo-ogino, Atsugi, Kanagawa, 243-0292 Japan
| | - Junpei Kato
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
| | - Midori Kobayashi
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
| | - Hyoung Jae Lee
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
| | - Yukihiro Sugimoto
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
| | - Yoko Iijima
- RIKEN Center for Sustainable Resource Science, Suehiro-cho 1-7-22, Tsurumi-ku, Yokohama, Kanagawa, 230-0045 Japan
| | - Kazuki Saito
- Department of Nutrition and Life Science, Kanagawa Institute of Technology, 1030 Shimo-ogino, Atsugi, Kanagawa, 243-0292 Japan
- Plant Molecular Science Center, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba, 260-8675 Japan
| | - Toshiya Muranaka
- Department of Biotechnology, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka, 565-0871 Japan
| | - Masaharu Mizutani
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
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13
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Nakayasu M, Umemoto N, Akiyama R, Ohyama K, Lee HJ, Miyachi H, Watanabe B, Muranaka T, Saito K, Sugimoto Y, Mizutani M. Characterization of C-26 aminotransferase, indispensable for steroidal glycoalkaloid biosynthesis. Plant J 2021; 108:81-92. [PMID: 34273198 DOI: 10.1111/tpj.15426] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 07/07/2021] [Accepted: 07/10/2021] [Indexed: 06/13/2023]
Abstract
Steroidal glycoalkaloids (SGAs) are toxic specialized metabolites found in members of the Solanaceae, such as Solanum tuberosum (potato) and Solanum lycopersicum (tomato). The major potato SGAs are α-solanine and α-chaconine, which are biosynthesized from cholesterol. Previously, we have characterized two cytochrome P450 monooxygenases and a 2-oxoglutarate-dependent dioxygenase that function in hydroxylation at the C-22, C-26 and C-16α positions, but the aminotransferase responsible for the introduction of a nitrogen moiety into the steroidal skeleton remains uncharacterized. Here, we show that PGA4 encoding a putative γ-aminobutyrate aminotransferase is involved in SGA biosynthesis in potatoes. The PGA4 transcript was expressed at high levels in tuber sprouts, in which SGAs are abundant. Silencing the PGA4 gene decreased potato SGA levels and instead caused the accumulation of furostanol saponins. Analysis of the tomato PGA4 ortholog, GAME12, essentially provided the same results. Recombinant PGA4 protein exhibited catalysis of transamination at the C-26 position of 22-hydroxy-26-oxocholesterol using γ-aminobutyric acid as an amino donor. Solanum stipuloideum (PI 498120), a tuber-bearing wild potato species lacking SGA, was found to have a defective PGA4 gene expressing the truncated transcripts, and transformation of PI 498120 with functional PGA4 resulted in the complementation of SGA production. These findings indicate that PGA4 is a key enzyme for transamination in SGA biosynthesis. The disruption of PGA4 function by genome editing will be a viable approach for accumulating valuable steroidal saponins in SGA-free potatoes.
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Affiliation(s)
- Masaru Nakayasu
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Kobe, Hyogo, 657-8501, Japan
| | - Naoyuki Umemoto
- RIKEN Center for Sustainable Resource Science, Suehiro-cho 1-7-22, Yokohama, Kanagawa, 230-0045, Japan
- Central Laboratories for Key Technologies, Kirin Co., Ltd. Fukuura 1-13-5, Yokohama, Kanagawa, 236-0004, Japan
| | - Ryota Akiyama
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Kobe, Hyogo, 657-8501, Japan
| | - Kiyoshi Ohyama
- Department of Chemistry and Materials Science, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro, Tokyo, 152-8551, Japan
| | - Hyoung J Lee
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Kobe, Hyogo, 657-8501, Japan
| | - Haruka Miyachi
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Kobe, Hyogo, 657-8501, Japan
| | - Bunta Watanabe
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011, Japan
| | - Toshiya Muranaka
- Department of Biotechnology, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka, 565-0871, Japan
| | - Kazuki Saito
- RIKEN Center for Sustainable Resource Science, Suehiro-cho 1-7-22, Yokohama, Kanagawa, 230-0045, Japan
| | - Yukihiro Sugimoto
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Kobe, Hyogo, 657-8501, Japan
| | - Masaharu Mizutani
- Graduate School of Agricultural Science, Kobe University, Rokkodai 1-1, Kobe, Hyogo, 657-8501, Japan
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14
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Shimizu K, Kushida A, Akiyama R, Lee HJ, Okamura Y, Masuda Y, Sakata I, Tanino K, Matsukida S, Inoue T, Sugimoto Y, Mizutani M. Hatching stimulation activity of steroidal glycoalkaloids toward the potato cyst nematode, Globodera rostochiensis. Plant Biotechnol (Tokyo) 2020; 37:319-325. [PMID: 33088195 PMCID: PMC7557651 DOI: 10.5511/plantbiotechnology.20.0516a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Cyst nematodes (Globodera spp. and Heterodera spp.) are highly evolved sedentary endoparasites that are considered as harmful pests worldwide. The hatching of the dormant eggs of cyst nematodes occurs in response to hatching factors (HFs), which are compounds that are secreted from the roots of host plants. Solanoeclepin A (SEA), a triterpene compound, has been isolated as HF for potato cyst nematode (PCN) eggs, whereas other compounds, such as steroidal glycoalkaloids (SGAs), are also known to show weak hatching stimulation (HS) activity. However, the structures of both compounds are different and the HF-mediated hatching mechanism is still largely unknown. In the present study, we observed specific hatching of PCN eggs stimulated by the hairy root culture media of potato and tomato, revealing the biosynthesis and secretion of HFs. SGAs, such as α-solanine, α-chaconine, and α-tomatine, showed significant HS activity, despite being remarkably less activities than that of SEA. Then, we evaluated the contribution of SGAs on the HS activities of the hairy root culture media. The estimated SGAs content in the hairy root culture media were low and nonconcordant with the HS activity of those, suggesting that the HS activity of SGAs did not contribute much. The analysis of structure-activity relationship revealed that the structural requirements of the HS activity of SGAs are dependent on the sugar moieties attached at the C3-hydoroxyl group and the alkaloid property of their aglycones. The stereochemistry in the EF rings of their aglycone also affected the strength of the HS activity.
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Affiliation(s)
- Kosuke Shimizu
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Atsuhiko Kushida
- Plant Nematology Group, Division of Agro-environmental Research, Hokkaido Agricultural Research Center, NARO, 1 Hitsujigaoka, Toyohira, Sapporo, Hokkaido 062-8555, Japan
| | - Ryota Akiyama
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Hyoung Jae Lee
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Yuya Okamura
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Yuki Masuda
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Itaru Sakata
- Plant Nematology Group, Division of Agro-environmental Research, Hokkaido Agricultural Research Center, NARO, 1 Hitsujigaoka, Toyohira, Sapporo, Hokkaido 062-8555, Japan
| | - Keiji Tanino
- Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
| | - Seiji Matsukida
- Odawara Research Center, Nippon Soda Co., Ltd., 345 Takada, Odawara, Kanagawa 250-0216, Japan
| | - Tsutomu Inoue
- Odawara Research Center, Nippon Soda Co., Ltd., 345 Takada, Odawara, Kanagawa 250-0216, Japan
| | - Yukihiro Sugimoto
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Masaharu Mizutani
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe, Hyogo 657-8501, Japan
- E-mail: Tel: +81-78-803-5885 Fax: +81-78-803-5884
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15
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Imura Y, Kan R, Akiyama R, Saito H, Morita-Imura C, Kawai T. Magnetic Fe 3O 4-Supported Gold Nanoflowers with Lattice-Selected Surfaces: Preparation and Catalytic Performance. ACS Omega 2020; 5:15755-15760. [PMID: 32637851 PMCID: PMC7331204 DOI: 10.1021/acsomega.0c02340] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 06/09/2020] [Indexed: 06/11/2023]
Abstract
Nanoflowers (NFs)-shape-controlled noble metal nanocrystals-have garnered significant attention because of their novel catalytic properties and applicability. In this paper, we report the preparation and catalytic performance of a magnetic Fe3O4-supported AuNF catalyst with a clean surface. The magnetically supported AuNFs were obtained by using magnetic Fe3O4 as the support. However, when nonmagnetic γ-Al2O3 was utilized as the support, the AuNFs did not exhibit a magnetic response. These supported AuNFs were utilized to catalyze the oxidation of 1-phenylethyl alcohol to acetophenone using air (1 atm) as the oxidant. The rate of formation of acetophenone using supported AuNFs was 8-fold higher than that of acetophenone using supported spherical Au nanoparticles of comparable size. In addition, the Fe3O4-supported AuNFs exhibited a higher rate of formation of acetophenone than the Al2O3-supported AuNFs. The Fe3O4-supported AuNFs were recovered using a magnet, and the recovered catalyst was reused under identical catalytic reaction conditions. The rate of formation of acetophenone using recovered Fe3O4-supported AuNFs remained unchanged, demonstrating no loss of catalytic activity.
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Affiliation(s)
- Yoshiro Imura
- Department
of Industrial Chemistry, Tokyo University
of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Ryota Kan
- Department
of Industrial Chemistry, Tokyo University
of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Ryota Akiyama
- Department
of Industrial Chemistry, Tokyo University
of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Haruna Saito
- Department
of Industrial Chemistry, Tokyo University
of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Clara Morita-Imura
- Department
of Chemistry, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan
| | - Takeshi Kawai
- Department
of Industrial Chemistry, Tokyo University
of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
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16
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Funakoshi Y, Imamura H, Tani S, Adachi H, Fukumitsu R, Sunohara T, Omura Y, Matsui Y, Sasaki N, Fukuda T, Akiyama R, Horiuchi K, Kajiura S, Shigeyasu M, Iihara K, Sakai N. Predictors of Cerebral Aneurysm Rupture after Coil Embolization: Single-Center Experience with Recanalized Aneurysms. AJNR Am J Neuroradiol 2020; 41:828-835. [PMID: 32381548 PMCID: PMC7228172 DOI: 10.3174/ajnr.a6558] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Accepted: 02/22/2020] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Recanalization after coil embolization is widely studied. However, there are limited data on how recanalized aneurysms rupture. Herein, we describe our experience with the rupture of recanalized aneurysms and discuss the type of recanalized aneurysms at greatest rupture risk. MATERIALS AND METHODS A total of 426 unruptured aneurysms and 169 ruptured aneurysms underwent coil embolization in our institution between January 2009 and December 2017. Recanalization occurred in 38 (8.9%) of 426 unruptured aneurysms (unruptured group) and 37 (21.9%) of 169 ruptured aneurysms (ruptured group). The Modified Raymond-Roy classification on DSA was used to categorize the recanalization type. Follow-up DSA was scheduled until 6 months after treatment, and follow-up MRA was scheduled yearly. If recanalization was suspected on MRA, DSA was performed. RESULTS In the unruptured group, the median follow-up term was 74.0 months. Retreatment for recanalization was performed in 18 aneurysms. Four of 20 untreated recanalized aneurysms (0.94% of total coiled aneurysms) ruptured. In untreated recanalized aneurysms, class IIIb aneurysms ruptured significantly more frequently than class II and IIIa (P = .025). In the ruptured group, the median follow-up term was 28.0 months. Retreatment for recanalization was performed in 16 aneurysms. Four of 21 untreated recanalized aneurysms (2.37% of total coiled aneurysms) ruptured. Class IIIb aneurysms ruptured significantly more frequently than class II and IIIa (P = .02). CONCLUSIONS The types of recanalization after coil embolization may be predictors of rupture. Coiled aneurysms with class IIIb recanalization should undergo early retreatment because of an increased rupture risk.
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Affiliation(s)
- Y Funakoshi
- From the Department of Neurosurgery (Y.F., H.I., S.T., H.A., R.F., T.S., Y.O., Y.M., N.Sasaki, T.F., R.A., K.H., S.K., M.S., N.Sakai), Kobe City Medical Center General Hospital, Kobe, Japan
| | - H Imamura
- From the Department of Neurosurgery (Y.F., H.I., S.T., H.A., R.F., T.S., Y.O., Y.M., N.Sasaki, T.F., R.A., K.H., S.K., M.S., N.Sakai), Kobe City Medical Center General Hospital, Kobe, Japan
| | - S Tani
- From the Department of Neurosurgery (Y.F., H.I., S.T., H.A., R.F., T.S., Y.O., Y.M., N.Sasaki, T.F., R.A., K.H., S.K., M.S., N.Sakai), Kobe City Medical Center General Hospital, Kobe, Japan
| | - H Adachi
- From the Department of Neurosurgery (Y.F., H.I., S.T., H.A., R.F., T.S., Y.O., Y.M., N.Sasaki, T.F., R.A., K.H., S.K., M.S., N.Sakai), Kobe City Medical Center General Hospital, Kobe, Japan
| | - R Fukumitsu
- From the Department of Neurosurgery (Y.F., H.I., S.T., H.A., R.F., T.S., Y.O., Y.M., N.Sasaki, T.F., R.A., K.H., S.K., M.S., N.Sakai), Kobe City Medical Center General Hospital, Kobe, Japan
| | - T Sunohara
- From the Department of Neurosurgery (Y.F., H.I., S.T., H.A., R.F., T.S., Y.O., Y.M., N.Sasaki, T.F., R.A., K.H., S.K., M.S., N.Sakai), Kobe City Medical Center General Hospital, Kobe, Japan
| | - Y Omura
- From the Department of Neurosurgery (Y.F., H.I., S.T., H.A., R.F., T.S., Y.O., Y.M., N.Sasaki, T.F., R.A., K.H., S.K., M.S., N.Sakai), Kobe City Medical Center General Hospital, Kobe, Japan
| | - Y Matsui
- From the Department of Neurosurgery (Y.F., H.I., S.T., H.A., R.F., T.S., Y.O., Y.M., N.Sasaki, T.F., R.A., K.H., S.K., M.S., N.Sakai), Kobe City Medical Center General Hospital, Kobe, Japan
| | - N Sasaki
- From the Department of Neurosurgery (Y.F., H.I., S.T., H.A., R.F., T.S., Y.O., Y.M., N.Sasaki, T.F., R.A., K.H., S.K., M.S., N.Sakai), Kobe City Medical Center General Hospital, Kobe, Japan
| | - T Fukuda
- From the Department of Neurosurgery (Y.F., H.I., S.T., H.A., R.F., T.S., Y.O., Y.M., N.Sasaki, T.F., R.A., K.H., S.K., M.S., N.Sakai), Kobe City Medical Center General Hospital, Kobe, Japan
| | - R Akiyama
- From the Department of Neurosurgery (Y.F., H.I., S.T., H.A., R.F., T.S., Y.O., Y.M., N.Sasaki, T.F., R.A., K.H., S.K., M.S., N.Sakai), Kobe City Medical Center General Hospital, Kobe, Japan
| | - K Horiuchi
- From the Department of Neurosurgery (Y.F., H.I., S.T., H.A., R.F., T.S., Y.O., Y.M., N.Sasaki, T.F., R.A., K.H., S.K., M.S., N.Sakai), Kobe City Medical Center General Hospital, Kobe, Japan
| | - S Kajiura
- From the Department of Neurosurgery (Y.F., H.I., S.T., H.A., R.F., T.S., Y.O., Y.M., N.Sasaki, T.F., R.A., K.H., S.K., M.S., N.Sakai), Kobe City Medical Center General Hospital, Kobe, Japan
| | - M Shigeyasu
- From the Department of Neurosurgery (Y.F., H.I., S.T., H.A., R.F., T.S., Y.O., Y.M., N.Sasaki, T.F., R.A., K.H., S.K., M.S., N.Sakai), Kobe City Medical Center General Hospital, Kobe, Japan
| | - K Iihara
- Department of Neurosurgery (K.I.), Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - N Sakai
- From the Department of Neurosurgery (Y.F., H.I., S.T., H.A., R.F., T.S., Y.O., Y.M., N.Sasaki, T.F., R.A., K.H., S.K., M.S., N.Sakai), Kobe City Medical Center General Hospital, Kobe, Japan
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Nakayasu M, Akiyama R, Kobayashi M, Lee HJ, Kawasaki T, Watanabe B, Urakawa S, Kato J, Sugimoto Y, Iijima Y, Saito K, Muranaka T, Umemoto N, Mizutani M. Identification of α-Tomatine 23-Hydroxylase Involved in the Detoxification of a Bitter Glycoalkaloid. Plant Cell Physiol 2020; 61:21-28. [PMID: 31816045 DOI: 10.1093/pcp/pcz224] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 12/03/2019] [Indexed: 05/13/2023]
Abstract
Tomato plants (Solanum lycopersicum) contain steroidal glycoalkaloid α-tomatine, which functions as a chemical barrier to pathogens and predators. α-Tomatine accumulates in all tissues and at particularly high levels in leaves and immature green fruits. The compound is toxic and causes a bitter taste, but its presence decreases through metabolic conversion to nontoxic esculeoside A during fruit ripening. This study identifies the gene encoding a 23-hydroxylase of α-tomatine, which is a key to this process. Some 2-oxoglutarate-dependent dioxygenases were selected as candidates for the metabolic enzyme, and Solyc02g062460, designated Sl23DOX, was found to encode α-tomatine 23-hydroxylase. Biochemical analysis of the recombinant Sl23DOX protein demonstrated that it catalyzes the 23-hydroxylation of α-tomatine and the product spontaneously isomerizes to neorickiioside B, which is an intermediate in α-tomatine metabolism that appears during ripening. Leaves of transgenic tomato plants overexpressing Sl23DOX accumulated not only neorickiioside B but also another intermediate, lycoperoside C (23-O-acetylated neorickiioside B). Furthermore, the ripe fruits of Sl23DOX-silenced transgenic tomato plants contained lower levels of esculeoside A but substantially accumulated α-tomatine. Thus, Sl23DOX functions as α-tomatine 23-hydroxylase during the metabolic processing of toxic α-tomatine in tomato fruit ripening and is a key enzyme in the domestication of cultivated tomatoes.
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Affiliation(s)
- Masaru Nakayasu
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
| | - Ryota Akiyama
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
| | - Midori Kobayashi
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
| | - Hyoung Jae Lee
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
| | - Takashi Kawasaki
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
| | - Bunta Watanabe
- Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011 Japan
| | - Shingo Urakawa
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
| | - Junpei Kato
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
| | - Yukihiro Sugimoto
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
| | - Yoko Iijima
- Department of Nutrition and Life Science, Kanagawa Institute of Technology, 1030 Shimo-ogino, Atsugi, Kanagawa, 243-0292 Japan
| | - Kazuki Saito
- Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba, 260-8675 Japan
- RIKEN Center for Sustainable Resource Science, Suehiro-cho 1-7-22, Tsurumi-ku, Yokohama, Kanagawa, 230-0045 Japan
| | - Toshiya Muranaka
- Department of Biotechnology, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka, 565-0871 Japan
| | - Naoyuki Umemoto
- RIKEN Center for Sustainable Resource Science, Suehiro-cho 1-7-22, Tsurumi-ku, Yokohama, Kanagawa, 230-0045 Japan
| | - Masaharu Mizutani
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501 Japan
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18
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Akiyama R, Lee HJ, Nakayasu M, Osakabe K, Osakabe Y, Umemoto N, Saito K, Muranaka T, Sugimoto Y, Mizutani M. Characterization of steroid 5α-reductase involved in α-tomatine biosynthesis in tomatoes. Plant Biotechnol (Tokyo) 2019; 36:253-263. [PMID: 31983879 PMCID: PMC6978498 DOI: 10.5511/plantbiotechnology.19.1030a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 10/30/2019] [Indexed: 05/19/2023]
Abstract
α-tomatine and dehydrotomatine are steroidal glycoalkaloids (SGAs) that accumulate in the mature green fruits, leaves, and flowers of tomatoes (Solanum lycopersicum) and function as defensive compounds against pathogens and predators. The aglycones of α-tomatine and dehydrotomatine are tomatidine and dehydrotomatidine (5,6-dehydrogenated tomatidine), and tomatidine is derived from dehydrotomatidine via four reaction steps: C3 oxidation, isomerization, C5α reduction, and C3 reduction. Our previous studies (Lee et al. 2019) revealed that Sl3βHSD is involved in the three reactions except for C5α reduction, and in the present study, we aimed to elucidate the gene responsible for the C5α reduction step in the conversion of dehydrotomatidine to tomatidine. We characterized the two genes, SlS5αR1 and SlS5αR2, which show high homology with DET2, a brassinosteroid 5α reductase of Arabidopsis thaliana. The expression pattern of SlS5αR2 is similar to those of SGA biosynthetic genes, while SlS5αR1 is ubiquitously expressed, suggesting the involvement of SlS5αR2 in SGA biosynthesis. Biochemical analysis of the recombinant proteins revealed that both of SlS5αR1 and SlS5αR2 catalyze the reduction of tomatid-4-en-3-one at C5α to yield tomatid-3-one. Then, SlS5αR1- or SlS5αR2-knockout hairy roots were constructed using CRISPR/Cas9 mediated genome editing. In the SlS5αR2-knockout hairy roots, the α-tomatine level was significantly decreased and dehydrotomatine was accumulated. On the other hand, no change in the amount of α-tomatine was observed in the SlS5αR1-knockout hairy root. These results indicate that SlS5αR2 is responsible for the C5α reduction in α-tomatine biosynthesis and that SlS5αR1 does not significantly contribute to α-tomatine biosynthesis.
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Affiliation(s)
- Ryota Akiyama
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkoudai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Hyoung Jae Lee
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkoudai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Masaru Nakayasu
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkoudai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Keishi Osakabe
- Faculty of Bioscience and Bioindustry, Tokushima University, Tokushima, Japan
| | - Yuriko Osakabe
- Faculty of Bioscience and Bioindustry, Tokushima University, Tokushima, Japan
| | - Naoyuki Umemoto
- RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Kazuki Saito
- RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
- Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan
| | - Toshiya Muranaka
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yukihiro Sugimoto
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkoudai, Nada, Kobe, Hyogo 657-8501, Japan
| | - Masaharu Mizutani
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkoudai, Nada, Kobe, Hyogo 657-8501, Japan
- E-mail: Tel: +81-78-803-5885 Fax: +81-78-803-5884
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19
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Wakabayashi T, Hamana M, Mori A, Akiyama R, Ueno K, Osakabe K, Osakabe Y, Suzuki H, Takikawa H, Mizutani M, Sugimoto Y. Direct conversion of carlactonoic acid to orobanchol by cytochrome P450 CYP722C in strigolactone biosynthesis. Sci Adv 2019; 5:eaax9067. [PMID: 32064317 PMCID: PMC6989309 DOI: 10.1126/sciadv.aax9067] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 11/01/2019] [Indexed: 05/18/2023]
Abstract
Strigolactones (SLs) are carotenoid-derived phytohormones and rhizosphere signaling molecules for arbuscular mycorrhizal fungi and root parasitic weeds. Why and how plants produce diverse SLs are unknown. Here, cytochrome P450 CYP722C is identified as a key enzyme that catalyzes the reaction of BC-ring closure leading to orobanchol, the most prevalent canonical SL. The direct conversion of carlactonoic acid to orobanchol without passing through 4-deoxyorobanchol is catalyzed by the recombinant enzyme. By knocking out the gene in tomato plants, orobanchol was undetectable in the root exudates, whereas the architecture of the knockout and wild-type plants was comparable. These findings add to our understanding of the function of the diverse SLs in plants and suggest the potential of these compounds to generate crops with greater resistance to infection by noxious root parasitic weeds.
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Affiliation(s)
- Takatoshi Wakabayashi
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Misaki Hamana
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Ayami Mori
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Ryota Akiyama
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Kotomi Ueno
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Keishi Osakabe
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima 770-8503, Japan
| | - Yuriko Osakabe
- Graduate School of Technology, Industrial and Social Sciences, Tokushima University, Tokushima 770-8503, Japan
| | - Hideyuki Suzuki
- Kazusa DNA Research Institute, Kazusa-kamatari 2-6-7, Kisarazu, Chiba 292-0818, Japan
| | - Hirosato Takikawa
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Masaharu Mizutani
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
| | - Yukihiro Sugimoto
- Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501, Japan
- Corresponding author.
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20
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Lee HJ, Nakayasu M, Akiyama R, Kobayashi M, Miyachi H, Sugimoto Y, Umemoto N, Saito K, Muranaka T, Mizutani M. Identification of a 3β-Hydroxysteroid Dehydrogenase/ 3-Ketosteroid Reductase Involved in α-Tomatine Biosynthesis in Tomato. Plant Cell Physiol 2019; 60:1304-1315. [PMID: 30892648 DOI: 10.1093/pcp/pcz049] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 03/11/2019] [Indexed: 06/09/2023]
Abstract
α-Tomatine and dehydrotomatine are major steroidal glycoalkaloids (SGAs) that accumulate in the mature green fruits, leaves and flowers of tomato (Solanum lycopersicum), and function as defensive compounds against bacteria, fungi, insects and animals. The aglycone of dehydrotomatine is dehydrotomatidine (5,6-dehydrogenated tomatidine, having the Δ5,6 double bond; the dehydro-type). The aglycone of α-tomatine is tomatidine (having a single bond between C5 and C6; the dihydro-type), which is believed to be derived from dehydrotomatidine via four reaction steps: C3 oxidation, isomerization, C5 reduction and C3 reduction; however, these conversion processes remain uncharacterized. In the present study, we demonstrate that a short-chain alcohol dehydrogenase/reductase designated Sl3βHSD is involved in the conversion of dehydrotomatidine to tomatidine in tomato. Sl3βHSD1 expression was observed to be high in the flowers, leaves and mature green fruits of tomato, in which high amounts of α-tomatine are accumulated. Biochemical analysis of the recombinant Sl3βHSD1 protein revealed that Sl3βHSD1 catalyzes the C3 oxidation of dehydrotomatidine to form tomatid-4-en-3-one and also catalyzes the NADH-dependent C3 reduction of a 3-ketosteroid (tomatid-3-one) to form tomatidine. Furthermore, during co-incubation of Sl3βHSD1 with SlS5αR1 (steroid 5α-reductase) the four reaction steps converting dehydrotomatidine to tomatidine were completed. Sl3βHSD1-silenced transgenic tomato plants accumulated dehydrotomatine, with corresponding decreases in α-tomatine content. Furthermore, the constitutive expression of Sl3βHSD1 in potato hairy roots resulted in the conversion of potato SGAs to the dihydro-type SGAs. These results demonstrate that Sl3βHSD1 is a key enzyme involved in the conversion processes from dehydrotomatidine to tomatidine in α-tomatine biosynthesis.
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Affiliation(s)
- Hyoung Jae Lee
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, Japan
| | - Masaru Nakayasu
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, Japan
| | - Ryota Akiyama
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, Japan
| | - Midori Kobayashi
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, Japan
| | - Haruka Miyachi
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, Japan
| | - Yukihiro Sugimoto
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, Japan
| | - Naoyuki Umemoto
- RIKEN Center for Sustainable Resource Science, Suehiro-cho 1-7-22, Tsurumi-ku, Yokohama, Kanagawa, Japan
| | - Kazuki Saito
- RIKEN Center for Sustainable Resource Science, Suehiro-cho 1-7-22, Tsurumi-ku, Yokohama, Kanagawa, Japan
- Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba, Japan
| | - Toshiya Muranaka
- Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka, Japan
| | - Masaharu Mizutani
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, Japan
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21
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Imura Y, Akiyama R, Furukawa S, Kan R, Morita-Imura C, Komatsu T, Kawai T. Au-Ag Nanoflower Catalysts with Clean Surfaces for Alcohol Oxidation. Chem Asian J 2019; 14:547-552. [PMID: 30600927 DOI: 10.1002/asia.201801711] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 12/25/2018] [Indexed: 12/30/2022]
Abstract
Shape-controlled metal nanocrystals, such as nanowires and nanoflowers, are attractive owing to their potentially novel catalytic properties and bimetallic nanocrystals composed of two distinct metals are expected to act as highly active catalysts. However, their catalytic activities are limited because of the capping agents adsorbed on the metal surfaces, which are necessary for the preparation and dispersion of these nanocrystals in solvents. Therefore, the preparation of bimetallic shape-controlled noble metal nanocrystals with clean surfaces, devoid of almost all capping agents, are expected to have high catalytic activity. Herein, we report the preparation of bimetallic Au-Ag nanoflowers using melamine as the capping agent. The bimetallic Au-Ag nanoflowers with a clean surface were subsequently obtained by a support and extraction method. The bimetallic nanoflowers with a clean surface were then used for the aerobic oxidation of 1-phenylethyl alcohol and they exhibited high rates for the formation of acetophenone compared to Au nanoflowers and spherical nanoparticles with almost the same size and Au/Ag ratio. We also show that Au-Ag nanoflowers containing only 1 % Ag (Au99 -Ag1 NFs) exhibit the highest rate of acetophenone formation among Au-Ag nanoflowers with different Au/Ag ratios owing to an increase in the electron density of the Au atoms that act as active sites for the oxidation of 1-phenylethyl alcohol.
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Affiliation(s)
- Yoshiro Imura
- Department of Industrial Chemistry, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan.,Department of Chemistry, Tokyo Institute of Technology, 2-12-1-E1-10 Ookayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Ryota Akiyama
- Department of Industrial Chemistry, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan
| | - Shinya Furukawa
- Institute for Catalysis, Hokkaido University, N21, W10, Kita-ku, Sapporo, 001-0021, Japan
| | - Ryota Kan
- Department of Industrial Chemistry, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan
| | - Clara Morita-Imura
- Faculty of Core Research, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo, 112-8610, Japan
| | - Takayuki Komatsu
- Department of Chemistry, Tokyo Institute of Technology, 2-12-1-E1-10 Ookayama, Meguro-ku, Tokyo, 152-8551, Japan
| | - Takeshi Kawai
- Department of Industrial Chemistry, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo, 162-8601, Japan
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22
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Imura Y, Kataoka H, Akiyama R, Morita‐Imura C, Kawai T. Preparation and Reconstruction of Long Branched Palladium Nanowires Exhibiting High Catalytic Activities. ChemistrySelect 2018. [DOI: 10.1002/slct.201803487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Yoshiro Imura
- Department of Industrial ChemistryTokyo University of Science, 1–3 Kagurazaka, Shinjuku-ku Tokyo 162–8601 Japan
| | - Hiroki Kataoka
- Department of Industrial ChemistryTokyo University of Science, 1–3 Kagurazaka, Shinjuku-ku Tokyo 162–8601 Japan
| | - Ryota Akiyama
- Department of Industrial ChemistryTokyo University of Science, 1–3 Kagurazaka, Shinjuku-ku Tokyo 162–8601 Japan
| | - Clara Morita‐Imura
- Faculty of Core ResearchOchanomizu University, 2–1-1 Otsuka, Bunkyo-ku Tokyo 112–8610 Japan
| | - Takeshi Kawai
- Department of Industrial ChemistryTokyo University of Science, 1–3 Kagurazaka, Shinjuku-ku Tokyo 162–8601 Japan
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23
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Nakayasu M, Akiyama R, Lee HJ, Osakabe K, Osakabe Y, Watanabe B, Sugimoto Y, Umemoto N, Saito K, Muranaka T, Mizutani M. Generation of α-solanine-free hairy roots of potato by CRISPR/Cas9 mediated genome editing of the St16DOX gene. Plant Physiol Biochem 2018; 131:70-77. [PMID: 29735370 DOI: 10.1016/j.plaphy.2018.04.026] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 04/22/2018] [Accepted: 04/22/2018] [Indexed: 05/20/2023]
Abstract
Potato (Solanum tuberosum) is a major food crop, while the most tissues of potato accumulates steroidal glycoalkaloids (SGAs) α-solanine and α-chaconine. Since SGAs confer a bitter taste on human and show the toxicity against various organisms, reducing the SGA content in the tubers is requisite for potato breeding. However, generation of SGA-free potato has not been achieved yet, although silencing of several SGA biosynthetic genes led a decrease in SGAs. Here, we show that the knockout of St16DOX encoding a steroid 16α-hydroxylase in SGA biosynthesis causes the complete abolition of the SGA accumulation in potato hairy roots. Nine candidate guide RNA (gRNA) target sequences were selected from St16DOX by in silico analysis, and the two or three gRNAs were introduced into a CRISPR/Cas9 vector designated as pMgP237-2A-GFP that can express multiplex gRNAs based on the pre-tRNA processing system. To establish rapid screening of the candidate gRNAs that can efficiently mutate the St16DOX gene, we used a potato hairy root culture system for the introduction of the pMgP237 vectors. Among the transgenic hairy roots, two independent lines showed no detectable SGAs but accumulated the glycosides of 22,26-dihydroxycholesterol, which is the substrate of St16DOX. Analysis of the two lines with sequencing exhibited the mutated sequences of St16DOX with no wild-type sequences. Thus, generation of SGA-free hairy roots of tetraploid potato was achieved by the combination of the hairy root culture and the pMgP237-2A-GFP vector. This experimental system is useful to evaluate the efficacy of candidate gRNA target sequences in the short-term.
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Affiliation(s)
- Masaru Nakayasu
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501, Japan.
| | - Ryota Akiyama
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Hyoung Jae Lee
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Keishi Osakabe
- Faculty of Bioscience and Bioindustry, Tokushima University, Tokushima, Japan
| | - Yuriko Osakabe
- Faculty of Bioscience and Bioindustry, Tokushima University, Tokushima, Japan
| | - Bunta Watanabe
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan
| | - Yukihiro Sugimoto
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Naoyuki Umemoto
- RIKEN Center for Sustainable Resource Science, Suehiro-cho 1-7-22, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
| | - Kazuki Saito
- RIKEN Center for Sustainable Resource Science, Suehiro-cho 1-7-22, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan; Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba, 260-8675, Japan
| | - Toshiya Muranaka
- Department of Biotechnology, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka, 565-0871, Japan
| | - Masaharu Mizutani
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501, Japan.
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24
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Nakayasu M, Akiyama R, Lee HJ, Osakabe K, Osakabe Y, Watanabe B, Sugimoto Y, Umemoto N, Saito K, Muranaka T, Mizutani M. Generation of α-solanine-free hairy roots of potato by CRISPR/Cas9 mediated genome editing of the St16DOX gene. Plant Physiol Biochem 2018. [PMID: 29735370 DOI: 10.1016/j.plaphy.2018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Potato (Solanum tuberosum) is a major food crop, while the most tissues of potato accumulates steroidal glycoalkaloids (SGAs) α-solanine and α-chaconine. Since SGAs confer a bitter taste on human and show the toxicity against various organisms, reducing the SGA content in the tubers is requisite for potato breeding. However, generation of SGA-free potato has not been achieved yet, although silencing of several SGA biosynthetic genes led a decrease in SGAs. Here, we show that the knockout of St16DOX encoding a steroid 16α-hydroxylase in SGA biosynthesis causes the complete abolition of the SGA accumulation in potato hairy roots. Nine candidate guide RNA (gRNA) target sequences were selected from St16DOX by in silico analysis, and the two or three gRNAs were introduced into a CRISPR/Cas9 vector designated as pMgP237-2A-GFP that can express multiplex gRNAs based on the pre-tRNA processing system. To establish rapid screening of the candidate gRNAs that can efficiently mutate the St16DOX gene, we used a potato hairy root culture system for the introduction of the pMgP237 vectors. Among the transgenic hairy roots, two independent lines showed no detectable SGAs but accumulated the glycosides of 22,26-dihydroxycholesterol, which is the substrate of St16DOX. Analysis of the two lines with sequencing exhibited the mutated sequences of St16DOX with no wild-type sequences. Thus, generation of SGA-free hairy roots of tetraploid potato was achieved by the combination of the hairy root culture and the pMgP237-2A-GFP vector. This experimental system is useful to evaluate the efficacy of candidate gRNA target sequences in the short-term.
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Affiliation(s)
- Masaru Nakayasu
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501, Japan.
| | - Ryota Akiyama
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Hyoung Jae Lee
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Keishi Osakabe
- Faculty of Bioscience and Bioindustry, Tokushima University, Tokushima, Japan
| | - Yuriko Osakabe
- Faculty of Bioscience and Bioindustry, Tokushima University, Tokushima, Japan
| | - Bunta Watanabe
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan
| | - Yukihiro Sugimoto
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Naoyuki Umemoto
- RIKEN Center for Sustainable Resource Science, Suehiro-cho 1-7-22, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
| | - Kazuki Saito
- RIKEN Center for Sustainable Resource Science, Suehiro-cho 1-7-22, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan; Graduate School of Pharmaceutical Sciences, Chiba University, Inohana 1-8-1, Chuo-ku, Chiba, 260-8675, Japan
| | - Toshiya Muranaka
- Department of Biotechnology, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka, 565-0871, Japan
| | - Masaharu Mizutani
- Graduate School of Agricultural Science, Kobe University, Rokkoudai 1-1, Nada-ku, Kobe, Hyogo, 657-8501, Japan.
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Endo Y, Ichinokura S, Akiyama R, Takayama A, Sugawara K, Nomura K, Takahashi T, Hasegawa S. Weak localization in bilayer graphene with Li-intercalation/desorption. J Phys Condens Matter 2018; 30:305701. [PMID: 29901452 DOI: 10.1088/1361-648x/aaccc4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We performed in-situ electrical transport measurements for bilayer graphene grown on SiC(0 0 0 1) substrate, Li-intercalated bilayer graphene, and after that desorbing Li atoms by heating. Bilayer graphene after desorbing intercalated Li atoms showed a higher resistivity and different behavior in magnetoconductance compared to pristine bilayer graphene. We observed the weak localization of carriers at low temperatures in all the three samples and analyzed the experimental results with the extended Hikami-Larkin-Nagaoka equation to investigate the transport properties. The result shows that the magnetoconductance of pristine bilayer graphene is described by the AB stacking structure model and the phase breaking scattering is dominated by the electron-electron scattering. The intra-valley scattering occurs most frequently probably due to dopants in SiC substrate. However, in Li-desorbed graphene, the magnetoconductance can be described by neither AB nor AA-stacking model, suggesting the coexistence of domains with several different stacking structures.
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Affiliation(s)
- Y Endo
- Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan
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26
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Akiyama R, Sumida K, Ichinokura S, Nakanishi R, Kimura A, Kokh KA, Tereshchenko OE, Hasegawa S. Shubnikov-de Haas oscillations in p and n-type topological insulator (Bi x Sb 1-x ) 2Te 3. J Phys Condens Matter 2018; 30:265001. [PMID: 29770777 DOI: 10.1088/1361-648x/aac59b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We show Shubnikov-de Haas (SdH) oscillations in topological insulator (Bi x Sb1-x )2Te3 flakes whose carrier types are p-type (x = 0.29, 0.34) and n-type (x = 0.42). The physical properties such as the Berry phase, carrier mobility, and scattering time significantly changed by tuning the Fermi-level position with the concentration x. The analyses of SdH oscillations by Landau-level fan diagram, Lifshitz-Kosevich theory, and Dingle-plot in the p-type samples with x = 0.29 and 0.34 showed the Berry phase of zero and a relatively low mobility (2000-6000 cm2 V-1 s-1). This is due to the dominant bulk component in transport. On the other hand, the mobility in the n-type sample with x = 0.42 reached a very large value ~17 000 cm2 V-1 s-1 and the Berry phase of near π, whereas the SdH oscillations were neither purely two- nor three-dimensional. These suggest that the transport channel has a surface-bulk coupling state which makes the carrier scattering lesser and enhances the mobility and has a character between two- and three-dimension.
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Affiliation(s)
- Ryota Akiyama
- Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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27
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Murata K, Akiyama R, Noro I, Nishio A, Nakagawa S, Yoshioka Y, Deguchi T, Matsuda H, Ishida Y. Search for effective plant materials for Alzheimer's disease. Am J Transl Res 2017. [DOI: 10.1055/s-0037-1608412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- K Murata
- Faculty of Pharmacy, Kindai University, Higashiosaka, Japan
| | - R Akiyama
- Faculty of Pharmacy, Kindai University, Higashiosaka, Japan
| | - I Noro
- Faculty of Pharmacy, Kindai University, Higashiosaka, Japan
| | - A Nishio
- Faculty of Pharmacy, Kindai University, Higashiosaka, Japan
| | - S Nakagawa
- Faculty of Pharmacy, Kindai University, Higashiosaka, Japan
| | | | - T Deguchi
- Faculty of Pharmacy, Kindai University, Higashiosaka, Japan
| | - H Matsuda
- Faculty of Pharmacy, Kindai University, Higashiosaka, Japan
| | - Y Ishida
- Faculty of Pharmacy, Kindai University, Higashiosaka, Japan
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28
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Hirahara T, Eremeev SV, Shirasawa T, Okuyama Y, Kubo T, Nakanishi R, Akiyama R, Takayama A, Hajiri T, Ideta SI, Matsunami M, Sumida K, Miyamoto K, Takagi Y, Tanaka K, Okuda T, Yokoyama T, Kimura SI, Hasegawa S, Chulkov EV. Large-Gap Magnetic Topological Heterostructure Formed by Subsurface Incorporation of a Ferromagnetic Layer. Nano Lett 2017; 17:3493-3500. [PMID: 28545300 DOI: 10.1021/acs.nanolett.7b00560] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Inducing magnetism into topological insulators is intriguing for utilizing exotic phenomena such as the quantum anomalous Hall effect (QAHE) for technological applications. While most studies have focused on doping magnetic impurities to open a gap at the surface-state Dirac point, many undesirable effects have been reported to appear in some cases that makes it difficult to determine whether the gap opening is due to the time-reversal symmetry breaking or not. Furthermore, the realization of the QAHE has been limited to low temperatures. Here we have succeeded in generating a massive Dirac cone in a MnBi2Se4/Bi2Se3 heterostructure, which was fabricated by self-assembling a MnBi2Se4 layer on top of the Bi2Se3 surface as a result of the codeposition of Mn and Se. Our experimental results, supported by relativistic ab initio calculations, demonstrate that the fabricated MnBi2Se4/Bi2Se3 heterostructure shows ferromagnetism up to room temperature and a clear Dirac cone gap opening of ∼100 meV without any other significant changes in the rest of the band structure. It can be considered as a result of the direct interaction of the surface Dirac cone and the magnetic layer rather than a magnetic proximity effect. This spontaneously formed self-assembled heterostructure with a massive Dirac spectrum, characterized by a nontrivial Chern number C = -1, has a potential to realize the QAHE at significantly higher temperatures than reported up to now and can serve as a platform for developing future "topotronics" devices.
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Affiliation(s)
- Toru Hirahara
- Department of Physics, Tokyo Institute of Technology , Tokyo 152-8551, Japan
| | - Sergey V Eremeev
- Institute of Strength Physics and Materials Science , Tomsk 634055, Russia
- Tomsk State University , Tomsk 634050, Russia
- Saint Petersburg State University , Saint Petersburg 198504, Russia
- Donostia International Physics Center (DIPC) , Paseo de Manuel Lardizabal, 4, 20018 San Sebastián/Donostia, Basque Country, Spain
| | - Tetsuroh Shirasawa
- Institute for Solid State Physics, University of Tokyo , Kashiwa 277-8581, Japan
| | - Yuma Okuyama
- Department of Physics, Tokyo Institute of Technology , Tokyo 152-8551, Japan
| | - Takayuki Kubo
- Department of Physics, University of Tokyo , Tokyo 113-0033, Japan
| | | | - Ryota Akiyama
- Department of Physics, University of Tokyo , Tokyo 113-0033, Japan
| | - Akari Takayama
- Department of Physics, University of Tokyo , Tokyo 113-0033, Japan
| | - Tetsuya Hajiri
- UVSOR Facility, Institute for Molecular Science , Okazaki 444-8585, Japan
| | - Shin-Ichiro Ideta
- UVSOR Facility, Institute for Molecular Science , Okazaki 444-8585, Japan
| | - Masaharu Matsunami
- UVSOR Facility, Institute for Molecular Science , Okazaki 444-8585, Japan
| | - Kazuki Sumida
- Graduate School of Science, Hiroshima University , Higashi-Hiroshima 739-8526, Japan
| | - Koji Miyamoto
- Hiroshima Synchrotron Radiation Center, Hiroshima University , Higashi-Hiroshima 739-8526, Japan
| | - Yasumasa Takagi
- Department of Materials Molecular Science, Institute for Molecular Science , Okazaki 444-8585, Japan
| | - Kiyohisa Tanaka
- UVSOR Facility, Institute for Molecular Science , Okazaki 444-8585, Japan
| | - Taichi Okuda
- Hiroshima Synchrotron Radiation Center, Hiroshima University , Higashi-Hiroshima 739-8526, Japan
| | - Toshihiko Yokoyama
- Department of Materials Molecular Science, Institute for Molecular Science , Okazaki 444-8585, Japan
| | - Shin-Ichi Kimura
- UVSOR Facility, Institute for Molecular Science , Okazaki 444-8585, Japan
| | - Shuji Hasegawa
- Department of Physics, University of Tokyo , Tokyo 113-0033, Japan
| | - Evgueni V Chulkov
- Tomsk State University , Tomsk 634050, Russia
- Saint Petersburg State University , Saint Petersburg 198504, Russia
- Donostia International Physics Center (DIPC) , Paseo de Manuel Lardizabal, 4, 20018 San Sebastián/Donostia, Basque Country, Spain
- Departamento de Física de Materiales, Facultad de Ciencias Químicas, UPV/EHU , Apdo. 1072, 20080 San Sebastián, Basque Country, Spain
- Centro de Física de Materiales, CFM-MPC, Centro Mixto CSIC-UPV/EHU , Apdo.1072, 20080 San Sebastián/Donostia, Basque Country, Spain
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Abstract
Shape-controlled nanocrystals, such as nanowires and nanoflowers, are attractive because of their potential novel optical and catalytic properties. However, the dispersion and morphological stabilities of shape-controlled nanocrystals are easily destroyed by changing the dispersion solvent and temperature. Methods of support and the silica coating are known to improve the dispersion and morphological stabilities of metal nanocrystals. The silica-coating method often causes morphological changes in shape-controlled nanocrystals because the silica coating is formed in mixed solutions of water and organic solvents such as ethanol, and this results in aggregation due to changes in the dispersion solvent. Furthermore, ligand exchange, designed to improve the dispersion stability in the solvent, often causes morphological changes. This article introduces a method for the preparation of highly stable silica-coated Au nanoflowers (AuNFs) supported on Al2O3. The method of support prevents the aggregation and precipitation of AuNFs when the solvent is changed from water to water/ethanol. Through stability improvement, silica coating of AuNFs/Al2O3 was conducted in water/ethanol without ligand exchange that causes morphological changes. Furthermore, silica-coated AuNFs/Al2O3 exhibit high morphological stability under high-temperature conditions compared to uncoated AuNFs/Al2O3. These results are very useful when preparing highly morphologically stable, silica-coated, shape-controlled nanocrystals without ligand exchange.
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Affiliation(s)
- Yoshiro Imura
- Department of Industrial Chemistry, Tokyo University of Science , 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Shiori Koizumi
- Department of Industrial Chemistry, Tokyo University of Science , 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Ryota Akiyama
- Department of Industrial Chemistry, Tokyo University of Science , 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
| | - Clara Morita-Imura
- Faculty of Core Research, Ochanomizu University , 2-1-1 Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan
| | - Takeshi Kawai
- Department of Industrial Chemistry, Tokyo University of Science , 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan
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Akiyama R, Fujisawa K, Sakurai R, Kuroda S. Weak antilocalization in (111) thin films of a topological crystalline insulator SnTe. ACTA ACUST UNITED AC 2014. [DOI: 10.1088/1742-6596/568/5/052001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Nakamura Y, Yoshimori A, Akiyama R. Effects of the solvation structure on diffusion of a large particle in a binary mixture studied by perturbation theory. J Mol Liq 2014. [DOI: 10.1016/j.molliq.2014.06.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Akiyama R, Ågren J. Conflicting selection on the timing of germination in a natural population of Arabidopsis thaliana. J Evol Biol 2013; 27:193-9. [DOI: 10.1111/jeb.12293] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 10/07/2013] [Accepted: 10/29/2013] [Indexed: 01/22/2023]
Affiliation(s)
- R. Akiyama
- Plant Ecology and Evolution; Department of Ecology and Genetics; Evolutionary Biology Centre; Uppsala University; Uppsala Sweden
- Institute of Evolutionary Biology and Environmental Studies; University of Zurich; Zurich Switzerland
- Division of Biological Science; Graduate School of Science; Nagoya University; Nagoya Japan
| | - J. Ågren
- Plant Ecology and Evolution; Department of Ecology and Genetics; Evolutionary Biology Centre; Uppsala University; Uppsala Sweden
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Tsuru T, Akiyama R, Kohashi K, Okumura K. [Case of a 13-year-old boy with hyponatremia due to lamotrigine-induced syndrome of inappropriate secretion of antidiuretic hormone]. No To Hattatsu 2012; 44:73-74. [PMID: 22352036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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Abstract
1. Among three types of fluctuations of instantaneous heart rate (IHR) found previously in newly hatched chicks, a high frequency oscillation with a mean frequency of about 0.7 Hz (Type I) appeared to be concurrent with breathing (Moriya et al., Comparative Biochemistry and Physiology, 124A: 461-468, 1999). 2. In order to confirm that Type I HR fluctuation is respiratory sinus arrhythmia (RSA), breathing activity was measured by a condenser microphone, simultaneously with IHR. 3. The microphone detected pressure changes caused by breathing (acoustorespirogram, ARG) and also unexpectedly movement, probably twitch, of hatchlings. 4. Simultaneous measurements of IHR and ARG demonstrated that oscillatory frequency of Type I HR fluctuation coincided with breathing frequency and IHR increased with inspiration, confirming that Type I HR oscillation is RSA. 5. In addition, large transient HR accelerations (Type III HR fluctuation) simultaneously occurred with movement or twitch of the hatchlings, suggesting that Type III HR fluctuation and movement of hatchlings have the same origin, probably sympathetic nerve function.
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Affiliation(s)
- K Moriya
- Department of Electrical and Electronic Engineering, Hakodate National College of Technology, Hakodate, Japan
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35
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Tsudzuki M, Onitsuka S, Akiyama R, Iwamizu M, Goto N, Nishibori M, Takahashi H, Ishikawa A. Identification of quantitative trait loci affecting shank length, body weight and carcass weight from the Japanese cockfighting chicken breed, Oh-Shamo (Japanese Large Game). Cytogenet Genome Res 2007; 117:288-95. [PMID: 17675870 DOI: 10.1159/000103190] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Accepted: 09/11/2006] [Indexed: 11/19/2022] Open
Abstract
We performed a quantitative trait locus (QTL) analysis to map QTLs controlling shank length, body weight, and carcass weight in a resource family of 245 F(2) birds developed from a cross of the large-sized, native, Japanese cockfighting breed, Oh-Shamo (Japanese Large Game), and the White Leghorn breed of chickens. Interval mapping revealed three significant QTLs for shank length on chromosomes 1, 4 and 24 at the experiment-wise 5% level, and a suggestive shank length QTL on chromosome 27 at the experiment-wise 10% level. For body weight two QTLs, one significant and the other suggestive, were identified on chromosomes 4 and 24, respectively. As expected, QTLs for carcass weight, which was highly correlated with body weight (r = 0.95), were detected at the same chromosomal locations as the detected body weight QTLs. Interestingly, the chromosomal locations containing these body weight and carcass weight QTLs coincided with those of two of the four shank length QTLs detected. No QTL with an epistatic interaction effect was discovered for any trait. The total contribution of all detected QTLs to genetic variance was 98.4%, 27.0% and 25.9% for shank length, body weight and carcass weight, respectively, indicating that most shank length QTLs have been identified but many body weight and carcass weight QTLs have been overlooked by the present analysis because of a low coverage rate of the 88 microsatellite markers used here (approximately 46% of the whole genome).
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Affiliation(s)
- M Tsudzuki
- Laboratory of Animal Breeding and Genetics, Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima, Japan.
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36
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37
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38
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Chiba Y, Fukuoka S, Niiya A, Akiyama R, Tazawa H. Development of cholinergic chronotropic control in chick (Gallus gallus domesticus) embryos. Comp Biochem Physiol A Mol Integr Physiol 2004; 137:65-73. [PMID: 14720592 DOI: 10.1016/s1095-6433(03)00271-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
In chick (Gallus gallus domesticus) embryos, instantaneous heart rate begins to fluctuate with the appearance of rapid, transient decelerations at around the end of the second week of incubation. Previously, it was shown that instantaneous heart rate decelerations were eliminated by administration of atropine and concurrently heart rate baseline was elevated in late embryos. Because the previous study lacked statistical treatment and there has been recent controversy over the development of tonic vagal control of the heart, we reexamine the hypothesis that transient decelerations of instantaneous heart rate are mediated by vagus nerve and the vagal tone begins to appear at around the end of the second week of incubation. Atropine administration tests were conducted for sixty-seven 11- to 14-day-old and 18-day-old embryos in total. Heart rate decelerations appeared sporadically in three out of ten 12-day-old embryos, but the difference of mode heart rate before and after administration of atropine was not significant. Seven out of nine 13-day-old embryos and all nine 14-day-old embryos showed heart rate decelerations and the difference of mode heart rate before and after atropine administration was significant. In late (18-day-old) embryos, magnitude and frequency of instantaneous heart rate decelerations further increased with additional appearance of transient, irregular accelerations. Administration of varying doses of atropine completely eliminated the heart rate decelerations and elevated the heart rate baseline more markedly than in young embryos, indicating the maturation of vagal tone late in incubation.
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Affiliation(s)
- Y Chiba
- Department of Electrical and Electronic Engineering, Muroran Institute of Technology, Mizumoto-cho, 27-1, 050-8585, Japan
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Tamura A, Akiyama R, Chiba Y, Moriya K, Dzialowski EM, Burggren WW, Tazawa H. Heart rate responses to cooling in emu hatchlings. Comp Biochem Physiol A Mol Integr Physiol 2003; 134:829-38. [PMID: 12814791 DOI: 10.1016/s1095-6433(03)00017-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Among fluctuations of instantaneous heart rate (IHR) in newly hatched chicks, heart rate (HR) oscillation with a mean frequency of 0.7 Hz has been designated as Type II HR variability characterized by low frequency (LF) oscillation [Comp. Biochem. Physiol. Part A 124 (1999) 461]. In response to exposure to lowered ambient temperature (Ta), chick hatchlings raised their HR baseline accompanied with the production or augmentation of Type II HR oscillation, indicating that LF oscillation is a phenomenon relating to thermoregulation [J. Therm. Biol. 26 (2001) 281]. In emu hatchlings that are precocial like chickens, Type II HR oscillation also occurred, but less frequently in comparison with chick hatchlings [Comp. Biochem. Physiol. Part A 131 (2002) 787]. This present experiment was conducted to elucidate how IHR of emu hatchlings responds to changes in Ta. Six hatchlings were measured for IHR and skin temperature (Ts) during a 3-h period when they were exposed to controlled Ta (ca. 35 degrees C), lowered Ta (ca. 15-30 degrees C) and again the controlled Ta for individual 1-h periods. In response to all the cooling and re-warming procedures, HR baseline changed depending upon the intensity of the Ta differences; i.e. large differences of Ta produced large changes in HR. HR fluctuations tended to augment during cooling with a few exceptions, but LF oscillation was not produced. Thus, LF oscillation, which was scarce even at the controlled Ta, could not be used as a thermoregulatory indicator in emus.
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Affiliation(s)
- A Tamura
- Department of Electrical and Electronic Engineering, Muroran Institute of Technology, Muroran 050-8585, Japan
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40
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Chiba Y, Khandoker AH, Nobuta M, Moriya K, Akiyama R, Tazawa H. Development of respiratory rhythms in perinatal chick embryos. Comp Biochem Physiol A Mol Integr Physiol 2002; 131:817-24. [PMID: 11897192 DOI: 10.1016/s1095-6433(02)00019-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In chick embryos, gas exchange takes place via the chorioallantoic membrane (CAM) and the lungs at approximately 1 day prior to hatching. The present study was designed to elucidate the development of respiratory rhythms in the chick embryo during the whole pipping (perinatal) period with a condenser-microphone measuring system. The microphone was hermetically attached on the eggshell over the air cell on day 18 of incubation. It first detected a cardiogenic signal (i.e. acoustocardiogram), and then beak clapping and breathing signals (acoustorespirogram, ARG). The first signals of lung ventilation appeared intermittently and irregularly approximately once per 5 s among the clapping signals after the embryo penetrated its beak into the air cell (internal pipping, IP). The respiratory rhythm then developed irregularly, with a subsequent more regular rate. The envelope pattern of breathing from the onset of IP through external pipping (EP) to hatching was constructed by a specially devised procedure, which eliminated external and internal noises. The envelope patterns indicated that the IP, EP and whole perinatal periods of 10 embryos were 14.1+/-6.4 (S.D.), 13.6+/-4.0 and 27.6+/-5.4 h, respectively. In addition, they also indicated the period of embryonic hatching activity (i.e. climax) which was 48+/-19 min. The development of respiratory rhythm was also shown by the instantaneous respiratory rate (IRR) which was designated as an inverse value of two adjacent ARG waves.
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Affiliation(s)
- Y Chiba
- Department of Electrical and Electronic Engineering, Muroran Institute of Technology, 050-8585, Muroran, Japan
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41
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Tanaka K, Yonetake K, Masuko T, Akiyama R. Shearing microscopy using polarized optical microscope with shear stage and spectral analyser to study liquid crystalline polymers. J Microsc 2002; 205:15-20. [PMID: 11856377 DOI: 10.1046/j.0022-2720.2001.00972.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In-situ polarized optical microscopy using a shear stage and a spectral analyser as well as a CCD camera were applied to study the phase transition under shear flow for a thermotropic and side-chain-type liquid crystalline polysiloxane. The onset of the appearance of anisotropic texture of the polysiloxane was observed under shear flow using the CCD camera at temperatures much higher than the isotropic-liquid crystalline phase transition temperature if the polysiloxane was cooled from the isotropic phase in the quiescent state. Both the onset temperature and the temperature for full development of the anisotropic texture across the field of view became higher as the shear rate increased. The transmitted light intensity was also measured using a spectral analyser with crossed polarisers at wavelengths from 300 nm to 800 nm, and the integrated intensity of the spectrum was calculated. Changes in the spectrum and the integrated intensity against temperature in the cooling process were compared with observation using the CCD camera. Temperature dependence of the integrated intensity showed that the onset of the appearance of the anisotropic texture under high shear rates was detected at temperatures slightly higher than that observed using the CCD camera.
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Affiliation(s)
- K Tanaka
- Department of Polymer Science and Engineering, Kyoto Institute of Technology, Matsugasaki, Kyoto 606-8585, Japan.
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43
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Kobayashi S, Ishida T, Akiyama R. Catalytic asymmetric dihydroxylation using phenoxyethoxymethyl-polystyrene (PEM)-based novel microencapsulated osmium tetroxide (PEM-MC OsO4). Org Lett 2001; 3:2649-52. [PMID: 11506600 DOI: 10.1021/ol0161965] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[reaction: see text]. A phenoxyethoxymethyl-polystyrene (PEM)-based novel polymer-supported osmium catalyst has been developed. The catalyst was readily prepared from PEM polymer based on a microencapsulation technique, and asymmetric dihydroxylation of olefins has been successfully performed using (DHQD)2PHAL as a chiral ligand and K3Fe(CN)6 as a cooxidant in H2O/acetone. The catalyst was recovered quantitatively by simple filtration and reused without loss of activity several times.
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Affiliation(s)
- S Kobayashi
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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Kobayashi S, Akiyama R, Kitagawa H. Polymer-supported glyoxylate and alpha-imino acetates. Versatile reagents for the synthesis of alpha-hydroxycarboxylic acid and alpha-amino acid libraries. J Comb Chem 2001; 3:196-204. [PMID: 11300861 DOI: 10.1021/cc0000850] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Polymer-supported glyoxylate.monohydrate (3) and alpha-imino acetates (7) have been readily prepared from chloromethylated resin via two or three steps. The ene reactions of 3 with alkenes were successfully performed in the presence of Yb(OTf)3 (50 mol %) to afford, after cleavage from the polymer support, the corresponding alpha-hydroxycarboxylic acid esters in good yields. The reactions of 7 with silyl enolates, Danishefsky's diene, and alkenes also proceeded smoothly in the presence of Sc(OTf)3 (20 mol %) to give the corresponding alpha-amino acid, pyridone, and tetrahydroquinoline derivatives, respectively, in good yields.
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Affiliation(s)
- S Kobayashi
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, CREST, Japan Science and Technology Corporation (JST), Hongo, Bunkyou-ku, Tokyo 113-0033, Japan
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Tanaka K, Oiwa Y, Kiguchi T, Akiyama R. Simultaneous optical observation of anisotropic texture for a concentrated solution of poly(γ-benzyl- l -glutamate) under transient stress response in shear flow. Colloid Polym Sci 2000. [DOI: 10.1007/s003960000388] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Tanaka K, Nakamura K, Akiyama R. Time scales for structural formation in an electrorheological suspension probed by optical and electrical responses. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 2000; 62:5378-5382. [PMID: 11089099 DOI: 10.1103/physreve.62.5378] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2000] [Indexed: 05/23/2023]
Abstract
Responses of the diffuse transmitted light intensity and the current passing through an electrorheological suspension to the stepwise electric field were measured in the quiescent state, and the time scales for the structural formation of the polarized particles were reported. It was found experimentally that both of the responses consist of plural modes, the faster and slower modes even in the quiescent state. The optical response was also expressed as an exponential function with two modes, which take place in succession.
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Affiliation(s)
- K Tanaka
- Department of Polymer Science and Engineering, Kyoto Institute of Technology, Matsugasaki, Kyoto 606-8585, Japan
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Kobayashi S, Akiyama R, Kitagawa H. Polymer-supported alpha-imino acetates. Versatile reagents for the synthesis of alpha-amino acid libraries. J Comb Chem 2000; 2:438-40. [PMID: 11029165 DOI: 10.1021/cc000015t] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- S Kobayashi
- Graduate School of Pharmaceutical Sciences, The University of Tokyo and CREST, Hongo, Bunkyou-ku, Tokyo 113-0033, Japan
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Akiyama R, Nagashima T, Tazawa H. Dynamical systems analysis of arterial blood pressure signals in relation to heart rate fluctuations in chick embryos. Comp Biochem Physiol A Mol Integr Physiol 1999; 124:469-74. [PMID: 10682245 DOI: 10.1016/s1095-6433(99)00139-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We attempted a new approach based on a modern dynamical system theory to reconstruct the arterial blood pressure signals in relation to heart rate fluctuations of developing chick embryos. The dynamical systems approach in general is to model a phenomenon that is presented by a single time series record and approximate the dynamical property (e.g. heart rate fluctuations) of a system based only on information contained in a single-variable (arterial blood pressure) of the system. The time-series data of the arterial blood pressure was reconstructed in 3-dimensional space to draw characteristic orbits. Since the reconstructed orbits of the blood pressure should retain information contained in the pressure signals, we attempted to derive instantaneous heart rate (IHR) from the reconstructed orbits. The derived IHR presenting HR fluctuations coincided well with the IHR obtained conventionally from the peak-to-peak time intervals of the maximum blood pressure. Movements of the reconstructed orbits of the arterial blood pressure in 3-dimensional space reflected HR fluctuations (i.e. transient decelerations and accelerations).
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Affiliation(s)
- R Akiyama
- Department of Electrical and Electronic Engineering, Muroran Institute of Technology, Japan
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Abstract
Taking advantage of acoustocardiogram (ACG), we measured the heart rate (HR) of chick embryos continuously from day 12 until hatching and then investigated the development of HR irregularities (HRI), HR variability (HRV), and the existence of a circadian rhythm in mean HR (MHR). HRI comprised transient bradycardia and tachycardia, which first developed on day 14 and 16 in most embryos, respectively. Transient bradycardia increased in frequency and magnitude with embryonic development and occurred over periods of up to 30 min in some embryos. MHR was maximal on around days 14-15 and thereafter decreased to about 250-260 bpm on days 16-18. Baseline HRV, which is an oscillation of the MHR baseline, occurred as HR decreased from days 15-16 and became predominant on days 17-18. The magnitude of the baseline oscillations reached up to 50 bpm in some embryos and the period ranged between about 40-90 min (ultradian rhythm). A circadian rhythm of MHR was not found in late chick embryos. On days 18-19, embryonic activities were augmented and then breathing movements began to occur, disturbing ACG signals and thus making it difficult to measure the HR. Instead, the development of breathing activities was recorded. Breathing frequency was irregular at first and then increased to a maximum of about 1.5 Hz prior to hatching.
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Affiliation(s)
- R Akiyama
- Department of Electrical and Electronic Engineering, Muroran Institute of Technology, Japan
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Abstract
Several human neurodegenerative disorders are caused by expansion of CAG repeats that occurs during meiosis or gametogenesis. We anticipated that the CAG repeats cloned in a plasmid of Saccharomyces cerevisiae might undergo a change in the number of repeats during meiosis and sporulation. To test this possibility, we devised a new method to change in vitro the number of CAG repeats and constructed plasmids carrying (CAG)39, (CAG)65 or (CAG)123 from a plasmid carrying (CAG)18. We monitored the number of colonies showing an altered length of the repeat tracts during mitosis and meiotic growth. Contraction of long CAG repeat was found to occur frequently, whereas a few cases of expansion were observed. The contraction was equally enhanced in both orientations when the host cells grew through meiosis. Thus, our results suggest that long CAG repeats are destabilized during meiosis or gametogenesis in S. cerevisiae.
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Affiliation(s)
- N Arai
- Department of Applied Biological Science, College of Bioresource Sciences, Nihon University, Kanagawa, Japan
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