148 results on '"Keitaro Tanoi"'
Search Results
2. Mutations in RZF1, a zinc-finger protein, reduce magnesium uptake in roots and translocation to shoots in rice
- Author
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Natsuko I Kobayashi, Hiroki Takagi, Xiaoyu Yang, Ayako Nishizawa-Yokoi, Tenta Segawa, Tatsuaki Hoshina, Takayuki Oonishi, Hisashi Suzuki, Ren Iwata, Seiichi Toki, Tomoko M Nakanishi, and Keitaro Tanoi
- Subjects
Physiology ,Genetics ,Plant Science - Abstract
Magnesium (Mg) homeostasis is critical for maintaining many biological processes, but little information is available to comprehend the molecular mechanisms regulating Mg concentration in rice (Oryza sativa). To make up for the lack of information, we aimed to identify mutants defective in Mg homeostasis through a forward genetic approach. As a result of the screening of 2,825 M2 seedlings mutated by ion-beam irradiation, we found a rice mutant that showed reduced Mg content in leaves and slightly increased Mg content in roots. Radiotracer 28Mg experiments showed that this mutant, named low-magnesium content 1 (LMGC1), has decreased Mg2+ influx in the root and Mg2+ translocation from root to shoot. Consequently, LMGC1 is sensitive to the low Mg condition and prone to develop chlorosis in the young mature leaf. The MutMap method identified a 7.4-kbp deletion in the LMGC1 genome leading to a loss of two genes. Genome editing using CRISPR-Cas9 further revealed that one of the two lost genes, a gene belonging to the RanBP2-type zinc-finger family that we named RanBP2-TYPE ZINC FINGER1 (OsRZF1), was the causal gene of the low Mg phenotype. OsRZF1 is a nuclear protein and may have a fundamental role in maintaining Mg homeostasis in rice plants.
- Published
- 2023
3. Development of the Practical Method for Ion Influx, Efflux, and Net Flux Measurement in Plant Roots
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Natsuko I. Kobayashi, Xiaoyu Yang, Ren Iwata, Hisashi Suzuki, Tomoko M. Nakanishi, and Keitaro Tanoi
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Radiation - Published
- 2022
4. Starch-dependent sodium accumulation in the leaves of Vigna riukiuensis
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Yusaku Noda, Atsushi Hirose, Mayumi Wakazaki, Mayuko Sato, Kiminori Toyooka, Naoki Kawachi, Jun Furukawa, Keitaro Tanoi, and Ken Naito
- Subjects
Plant Science - Abstract
This research provides insight into a unique salt tolerance mechanism of Vigna riukiuensis. V. riukiuensis is one of the salt-tolerant species identified from the genus Vigna. We have previously reported that V. riukiuensis accumulates a higher amount of sodium in the leaves, whereas V. nakashimae, a close relative of V. riukiuensis, suppresses sodium allocation to the leaves. We first suspected that V. riukiuensis would have developed vacuoles for sodium sequestration, but there were no differences compared to a salt-sensitive species V. angularis. However, many starch granules were observed in the chloroplasts of V. riukiuensis. In addition, forced degradation of leaf starch by shading treatment resulted in no radio-Na (22Na) accumulation in the leaves. We performed SEM–EDX to locate Na in leaf sections and detected Na in chloroplasts of V. riukiuensis, especially around the starch granules but not in the middle of. Our results could provide the second evidence of the Na-trapping system by starch granules, following the case of common reed that accumulates starch granule at the shoot base for binding Na.
- Published
- 2023
5. Different phenotypic responses in the root of Vigna marina and Vigna luteola under salt stress
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Fanmiao Wang, Yurie Iki, Keitaro Tanoi, and Ken Naito
- Abstract
Some wild species in vigna genus are halophyte that have high potential in salt tolerance. V. marina and one accession of V. luteola have been previously identified as salt tolerant. However, the mechanisms remain elusive and studies on the phenotypic responses to salt can be a starting point for understanding salt tolerant mechanisms. Additional to salt accumulation and leaf chlorophyll fluorescence, this study evaluated root system architecture, including total root length, root surface area and root tip number, in response to salt. Results demonstrate 1) V. marina maintained total root length and surface area in salt stress; 2) V. marina grew more but shorter fine roots in salt stress; 3) The leaves of V. luteola-beach tolerated high Na concentration which severely damaged those of V. luteola-river, and such damage started from older leaf while it happened from younger leaf in V. luteola-beach. This is the first report on root architectural change in response to salt in Vigna genus. Our results suggest importance of studying relationship between root architecture and salt tolerance.
- Published
- 2023
6. Nicotiana benthamiana XYLEM CYSTEINE PROTEASE genes facilitate tracheary element formation in interfamily grafting
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Chaokun Huang, Ken-ichi Kurotani, Ryo Tabata, Nobutaka Mitsuda, Ryohei Sugita, Keitaro Tanoi, and Michitaka Notaguchi
- Subjects
Genetics ,Plant Science ,Horticulture ,Biochemistry ,Biotechnology - Abstract
Grafting is a plant propagation technique widely used in agriculture. A recent discovery of the capability of interfamily grafting in Nicotiana has expanded the potential combinations of grafting. In this study, we showed that xylem connection is essential for the achievement of interfamily grafting and investigated the molecular basis of xylem formation at the graft junction. Transcriptome and gene network analyses revealed gene modules for tracheary element (TE) formation during grafting that include genes associated with xylem cell differentiation and immune response. The reliability of the drawn network was validated by examining the role of the Nicotiana benthamiana XYLEM CYSTEINE PROTEASE (NbXCP) genes in TE formation during interfamily grafting. Promoter activities of NbXCP1 and NbXCP2 genes were found in differentiating TE cells in the stem and callus tissues at the graft junction. Analysis of a Nbxcp1;Nbxcp2 loss-of-function mutant indicated that NbXCPs control the timing of de novo TE formation at the graft junction. Moreover, grafts of the NbXCP1 overexpressor increased the scion growth rate as well as the fruit size. Thus, we identified gene modules for TE formation at the graft boundary and demonstrated potential ways to enhance Nicotiana interfamily grafting.
- Published
- 2023
7. Distinct Functions of the Atypical Terminal Hydrophilic Domain of the HKT Transporter in the Liverwort Marchantia polymorpha
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Shahin Imran, Masumi Oyama, Rie Horie, Natsuko I Kobayashi, Alex Costa, Ryosuke Kumano, Chiho Hirata, Sen Thi Huong Tran, Maki Katsuhara, Keitaro Tanoi, Takayuki Kohchi, Kimitsune Ishizaki, and Tomoaki Horie
- Subjects
DNA, Complementary ,HKT ,K+ transport ,Marchantia polymorpha ,Na+ transport ,Physiology ,Sodium ,Marchantia ,Oryza ,Cell Biology ,Plant Science ,General Medicine ,Cation Transport Proteins ,Phylogeny ,Plant Proteins - Abstract
K+/Na+ homeostasis is important for land plants, particularly under salt stress. In this study, the structure and ion transport properties of the high-affinity K+ transporter (HKT) of the liverwort Marchantia polymorpha were investigated. Only one HKT gene, MpHKT1, was identified in the genome of M. polymorpha. Phylogenetic analysis of HKT proteins revealed that non-seed plants possess HKTs grouped into a clade independent of the other two clades including HKTs of angiosperms. A distinct long hydrophilic domain was found in the C-terminus of MpHKT1. Complementary DNA (cDNA) of truncated MpHKT1 (t-MpHKT1) encoding the MpHKT_Δ596-812 protein was used to examine the functions of the C-terminal domain. Both MpHKT1 transporters fused with enhanced green fluorescent protein at the N-terminus were localized to the plasma membrane when expressed in rice protoplasts. Two-electrode voltage clamp experiments using Xenopus laevis oocytes indicated that MpHKT1 mediated the transport of monovalent alkali cations with higher selectivity for Na+ and K+, but truncation of the C-terminal domain significantly reduced the transport activity with a decrease in the Na+ permeability. Overexpression of MpHKT1 or t-MpHKT1 in M. polymorpha conferred accumulation of higher Na+ levels and showed higher Na+ uptake rates, compared to those of wild-type plants; however, phenotypes with t-MpHKT1 were consistently weaker than those with MpHKT1. Together, these findings suggest that the hydrophilic C-terminal domain plays a unique role in the regulation of transport activity and ion selectivity of MpHKT1.
- Published
- 2022
8. Diversity of Na+ allocation in salt-tolerant species of the genus Vigna
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Yusaku Noda, Ryohei Sugita, Atsushi Hirose, Naoki Kawachi, Keitaro Tanoi, Jun Furukawa, and Ken Naito
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Genetics ,Plant Science ,Agronomy and Crop Science - Published
- 2022
9. Nicotiana benthamiana XYLEM CYSTEINE PROTEASEgenes facilitate tracheary element formation in interfamily grafting
- Author
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Chaokun Huang, Ken-ichi Kurotani, Ryo Tabata, Nobutaka Mitsuda, Ryohei Sugita, Keitaro Tanoi, and Michitaka Notaguchi
- Abstract
Grafting is a plant propagation technique widely used in agriculture. A recent discovery of the capability of interfamily grafting inNicotianahas expanded the potential combinations of grafting. In this study, we showed that xylem connection is essential for the achievement of interfamily grafting and investigated the molecular basis of xylem formation at the graft junction. Transcriptome and gene network analyses revealed gene modules for tracheary element (TE) formation during grafting that include genes associated with xylem cell differentiation and immune response. The reliability of the drawn network was validated by examining the role of theNicotiana benthamiana XYLEM CYSTEINE PROTEASE (NbXCP)genes in TE formation during interfamily grafting. Promoter activities ofNbXCP1andNbXCP2genes were found in differentiating TE cells in the stem and callus tissues at the graft junction. Analysis of aNbxcp1;Nbxcp2loss-of-function mutant indicated thatNbXCPscontrol the timing ofde novoTE formation at the graft junction. Moreover, grafts of theNbXCP1overexpressor increased the scion growth rate as well as the fruit size. Thus, we identified gene modules for TE formation at the graft boundary and demonstrated potential ways to enhanceNicotianainterfamily grafting.
- Published
- 2022
10. A fungal secondary metabolism gene cluster enables mutualist-pathogen transition in root endophyte Colletotrichum tofieldiae
- Author
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Kei Hiruma, Seishiro Aoki, Yuniar Devi Utami, Masanori Okamoto, Nanami Kawamura, Masami Nakamura, Yoshihiro Ohmori, Ryohei Sugita, Keitaro Tanoi, Toyozo Sato, Wataru Iwasaki, and Yusuke Saijo
- Abstract
SUMMARYPlant-associated fungi show diverse lifestyles from pathogenic to mutualistic to the host; however, the principles and mechanisms through which they shift the lifestyles require elucidation. The root fungus Colletotrichum tofieldiae (Ct) promotes Arabidopsis thaliana growth under phosphate limiting conditions. We reveal a Ct strain, designated Ct3, that severely inhibits plant growth. Ct3 pathogenesis occurs through activation of host abscisic acid (ABA) pathways via a fungal secondary metabolism gene cluster related to sesquiterpene ABA and botrydial (BOT) biosynthesis. ABA-BOT cluster activation during root infection suppresses host nutrient uptake-related genes and changes the mineral contents, suggesting its role in manipulating host nutrition states. Conversely, disruption or environmental suppression of the cluster renders Ct3 beneficial for plant growth, in a manner dependent on host phosphate starvation response regulators. Our findings indicate that a fungal metabolism cluster provides a means by which infectious fungi modulate lifestyles along the parasitic–mutualistic continuum in fluctuating environments.
- Published
- 2022
11. Mutations in OsRZF1, encoding a zinc-finger protein, causes reduced magnesium uptake in roots and translocation to shoots in rice
- Author
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Natsuko I. Kobayashi, Hiroki Takagi, Xiaoyu Yang, Ayako Nishizawa-Yokoi, Tatsuaki Hoshina, Takayuki Oonishi, Hisashi Suzuki, Ren Iwata, Seiichi Toki, Tomoko M. Nakanishi, and Keitaro Tanoi
- Abstract
Magnesium (Mg) homeostasis is critical for maintaining many biological processes, but little information is available to comprehend the molecular mechanisms regulating Mg concentration in rice (Oryza sativa). To make up for the lack of information, we aimed to identify mutants defective in Mg homeostasis through a forward genetic approach. As a result of the screening of about 3,000 M2 seedlings mutated by ion-beam irradiation, we found a rice mutant that showed reduced Mg content in leaves and slightly increased Mg content in roots. Radiotracer 28Mg experiments showed that this mutant, named low magnesium content 1 (LMGC1), has decreased Mg2+ influx in the root and Mg2+ translocation from root to shoot. The MutMap method identified 7.4 kbp deletion in the LMGC1 genome leading to a loss of two genes. Genome editing using CRISPR-Cas9 further revealed that one of the two lost genes, a gene belonging to RanBP2-type zinc finger family, was the causal gene of the low-Mg phenotype. Considering this gene, named OsRZF1, has never been reported to be involved in ion transport, the phenotype of LMGC1 would be associated with a novel mechanism of Mg homeostasis in plants.
- Published
- 2022
12. ATP binding cassette proteins ABCG37 and ABCG33 function as potassium-independent cesium uptake carriers in Arabidopsis roots
- Author
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Ryohei Sugita, Keitaro Tanoi, Mohammad Arif Ashraf, Abidur Rahman, Sayaka Kumagai, Takashi Akihiro, and Keita Ito
- Subjects
0106 biological sciences ,0301 basic medicine ,Potassium ,Mutant ,Arabidopsis ,Cesium ,Heterologous ,chemistry.chemical_element ,ATP Binding Cassette Transporter, Subfamily G ,ATP-binding cassette transporter ,Plant Science ,Plant Roots ,01 natural sciences ,03 medical and health sciences ,Molecular Biology ,biology ,Arabidopsis Proteins ,Biological Transport ,Transporter ,biology.organism_classification ,Yeast ,030104 developmental biology ,Biochemistry ,chemistry ,Function (biology) ,010606 plant biology & botany - Abstract
Radiocesium accumulated in the soil by nuclear accidents is a major environmental concern. The transport process of cesium (Cs+) is tightly linked to the indispensable plant nutrient potassium (K+) as they both belong to the group I alkali metals with similar chemical properties. Most of the transporters that had been characterized to date as Cs+ transporters are directly or indirectly linked to K+. Using a combinatorial approach of physiology, genetics, cell biology, and root uptake assay, here we identified two ATP-binding cassette (ABC) proteins, ABCG37 and ABCG33, as facilitators of Cs+ influx. A gain-of-function mutant of ABCG37 (abcg37-1) showed increased sensitivity to Cs+-induced root growth inhibition, while the double knockout mutant of ABCG33 and ABCG37 (abcg33-1abcg37-2) showed resistance, whereas the single loss-of-function mutants of ABCG33 and ABCG37 did not show any alteration in Cs+ response. In planta short-term radioactive Cs+-uptake assay along with growth and uptake assays in a heterologous system confirmed ABCG33 and ABCG37 as Cs+-uptake carriers. Potassium response and content were unaffected in the double-mutant background and yeast cells lacking potassium-uptake carriers transformed with ABCG33 and ABCG37 failed to grow in the absence of K+, confirming that Cs+ uptake by ABCG33 and ABCG37 is independent of K+. Collectively, this work identified two ABC proteins as new Cs+-influx carriers that act redundantly and independent of the K+-uptake pathway.
- Published
- 2021
13. Metal accumulation and its effect on leaf herbivory in an allopolyploid species Arabidopsis kamchatica inherited from a diploid hyperaccumulator <scp> A. halleri </scp>
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Rie Shimizu-Inatsugi, Gabriela Schaepman-Strub, Kentaro Shimizu, Yasuhiro Sato, Keitaro Tanoi, and Silvija Milosavljevic
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0106 biological sciences ,Herbivore ,Cadmium ,Ecology ,Arabidopsis halleri ,food and beverages ,chemistry.chemical_element ,Plant Science ,Zinc ,Biology ,010603 evolutionary biology ,01 natural sciences ,Metal ,chemistry ,visual_art ,Botany ,Arabidopsis kamchatica ,visual_art.visual_art_medium ,Hyperaccumulator ,Ploidy ,Ecology, Evolution, Behavior and Systematics - Abstract
Excessive amounts of metal ions in soil are toxic for most plant species, yet metal can also facilitate plant survival by elemental defense against herbivores and pathogens. Zinc and cadmium hyperaccumulation in Arabidopsis halleri is known to be effective for the defense against natural enemies. The allotetraploid species A. kamchatica, derived from A. halleri and a non‐hyperaccumulator A. lyrata, has a lower hyperaccumulation level of zinc than A. halleri, but its significance for elemental defense remains unknown. In this study, we evaluated the accumulation levels of zinc and cadmium in the allotetraploid compared with its diploid progenitors, and evaluated the contribution of metal treatments to anti‐herbivore resistance under field conditions. The accumulation level of zinc in A. kamchatica was intermediate between the progenitors, but that of cadmium was lower than in both diploid progenitors. The elemental defense of A. kamchatica and A. halleri was supported by a field experiment comparing the herbivory level between a control group and metal‐supplemented plants. Moreover, the effect of elemental defense was lower in A. kamchatica than in the hyperaccumulator progenitor A. halleri, which is consistent with the metal accumulation level. This result reveals that the allotetraploid plant inherited its hyperaccumulating ability from one progenitor as an advantageous trait but at an intermediate level.
- Published
- 2020
14. Cover Image
- Author
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Yuko Kurita, Satomi Kanno, Ryohei Sugita, Atsushi Hirose, Miwa Ohnishi, Ayumi Tezuka, Ayumi Deguchi, Kimitsune Ishizaki, Hidehiro Fukaki, Kei'ichi Baba, Atsushi J. Nagano, Keitaro Tanoi, Tomoko M. Nakanishi, and Tetsuro Mimura
- Subjects
Physiology ,Plant Science - Published
- 2022
15. Isotope-based visualization of element distribution in phloem provides functional evidence for the operation of SOS1 Na+/H+ exchangers in mature zones of Arabidopsis root
- Author
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Ryohei Sugita, Takaaki Ogura, Natsuko I. Kobayashi, Muhammad B. Gill, Lana Shabala, Tomoko M. Nakanishi, Sergey Shabala, and Keitaro Tanoi
- Abstract
In the phloem, various solutes such as photosynthates, mineral nutrients, or toxic elements move from the source organs to sinks. One of them is the root. While this process may mediate significant quantities of solutes delivered to the root, it is unclear how the solutes are distributed along the root axis. To elucidate the distributing pattern of solutes, we visually analyzed the movement of solutes in Arabidopsis roots using a radioisotope imaging technique. The distribution patterns fell into four different groups: (1) root tip accumulation for 14C-photosynthates, 28Mg2+, 32PO43-, and 35SO42-; (2) homogenous distribution along the root axis for 42K+ and 137Cs+; (3) no detectable accumulation in the root for 45Ca2+ and 59Fe2+; and (4) transient accumulation in the root for 22Na+. The latter phenomenon was explored in more detail using Arabidopsis knockout mutants lacking functional sodium efflux transporter SOS1 (operating as Na+/H+ exchanger). By utilizing a non-invasive microelectrode MIFE ion flux measuring technique, we found that Na+ efflux was active in the mature root zone of wild-type Arabidopsis plants but not in root apex as initially thought, and that in sos1 mutants lacking functional Na+/H+ exchangers, shoot-derived 22Na+ remained in the root. These findings challenge the notion that Na+ exclusion via SOS1 is confined to the root apex and demonstrates the power of combining the radioisotope imaging technique and the MIFE ion flux measuring technique to study the kinetics of ion transport in the root and root-to-shoot communication.
- Published
- 2022
16. Visualization of phosphorus re-translocation and phosphate transporter expression profiles in a shortened annual cycle system of poplar
- Author
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Yuko Kurita, Satomi Kanno, Ryohei Sugita, Atsushi Hirose, Miwa Ohnishi, Ayumi Tezuka, Ayumi Deguchi, Kimitsune Ishizaki, Hidehiro Fukaki, Kei'ichi Baba, Atsushi J. Nagano, Keitaro Tanoi, Tomoko M. Nakanishi, and Tetsuro Mimura
- Subjects
Plant Leaves ,Populus ,Physiology ,Xylem ,Phosphate Transport Proteins ,Phosphorus ,Plant Science ,Phloem ,Trees - Abstract
Phosphorus (P) is an essential macronutrient for plant growth. In deciduous trees, P is remobilized from senescing leaves and stored in perennial tissues during winter for further growth. Annual internal recycling and accumulation of P are considered an important strategy to support the vigorous growth of trees. However, the pathways of seasonal re-translocation of P and the molecular mechanisms of this transport have not been clarified. Here we show the seasonal P re-translocation route visualized using real-time radioisotope imaging and the macro- and micro-autoradiography. We analysed the seasonal re-translocation P in poplar (Populus alba. L) cultivated under 'a shortened annual cycle system', which mimicked seasonal phenology in a laboratory. From growing to senescing season, sink tissues of
- Published
- 2022
17. Phosphate starvation response precedes abscisic acid response under progressive mild drought in plants
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Yukari Nagatoshi, Kenta Ikazaki, Yasufumi Kobayashi, Nobuyuki Mizuno, Ryohei Sugita, Yumiko Takebayashi, Mikiko Kojima, Hitoshi Sakakibara, Natsuko I. Kobayashi, Keitaro Tanoi, Kenichiro Fujii, Junya Baba, Eri Ogiso-Tanaka, Masao Ishimoto, Yasuo Yasui, Tetsuji Oya, and Yasunari Fujita
- Subjects
chemistry.chemical_compound ,Drought stress ,Horticulture ,Inorganic phosphate ,chemistry ,Crop production ,parasitic diseases ,fungi ,food and beverages ,Wilting ,Biology ,Phosphate ,Starvation response - Abstract
Drought severely damages crop production, even under conditions so mild that the leaves show no signs of wilting. However, it is unclear how field-grown plants respond to mild drought. Here, we show through 6 years of field trials that ridges are a useful experimental tool to mimic mild drought stress in the field. Mild drought reduces inorganic phosphate levels in the leaves to activate the phosphate starvation response in soybean plants in the field. UsingArabidopsis thalianaand its mutant plants grown in pots under controlled environments, we demonstrate that phosphate starvation response (PSR) occurs before abscisic acid response under progressive mild drought and that PSR plays a crucial role in plant growth under mild drought. Our observations in the field and laboratory using model crop and experimental plants provide insight into the molecular response to mild drought in field-grown plants and the relationship between nutrition and drought stress response.
- Published
- 2021
18. Systemic Regulation of Iron Acquisition by Arabidopsis in Environments with Heterogeneous Iron Distributions
- Author
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Ryo Tabata, Takehiro Kamiya, Shunpei Imoto, Hana Tamura, Kumiko Ikuta, Michika Tabata, Tasuku Hirayama, Hironaka Tsukagoshi, Keitaro Tanoi, Takamasa Suzuki, Takushi Hachiya, and Hitoshi Sakakibara
- Subjects
Physiology ,Arabidopsis Proteins ,Coumarins ,Gene Expression Regulation, Plant ,Iron ,Arabidopsis ,Humans ,Membrane Transport Proteins ,Cell Biology ,Plant Science ,General Medicine ,Plant Roots - Abstract
Nutrient distribution within the soil is generally heterogeneous. Plants, therefore, have evolved sophisticated systemic processes enabling them to optimize their nutrient acquisition efficiency. By organ-to-organ communication in Arabidopsis thaliana, for instance, iron (Fe) starvation in one part of a root drives the upregulation of a high-affinity Fe-uptake system in other root regions surrounded by sufficient levels of Fe. This compensatory response through Fe-starvation-triggered organ-to-organ communication includes the upregulation of Iron-regulated transporter 1 (IRT1) gene expression on the Fe-sufficient side of the root; however, the molecular basis underlying this long-distance signaling remains unclear. Here, we analyzed gene expression by RNA-seq analysis of Fe-starved split-root cultures. Genome-wide expression analysis showed that localized Fe depletion in roots upregulated several genes involved in Fe uptake and signaling, such as IRT1, in a distant part of the root exposed to Fe-sufficient conditions. This result indicates that long-distance signaling for Fe demand alters the expression of a subset of genes responsible for Fe uptake and coumarin biosynthesis to maintain a level of Fe acquisition sufficient for the entire plant. Loss of IRON MAN/FE-UPTAKE-INDUCING PEPTIDE (IMA/FEP) leads to the disruption of compensatory upregulation of IRT1 in the root surrounded by sufficient Fe. In addition, our split-root culture-based analysis provides evidence that the IMA3/FEP1-MYB10/72 pathway mediates long-distance signaling in Fe homeostasis through the regulation of coumarin biosynthesis. These data suggest that the signaling of IMA/FEP, a ubiquitous family of metal-binding peptides, is critical for organ-to-organ communication in response to Fe starvation under heterogeneous Fe conditions in the surrounding environment.
- Published
- 2021
19. Radiation Imaging in Plant Science
- Author
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Naoki Kawachi, Jun Furukawa, Nobuo Suzui, and Keitaro Tanoi
- Subjects
Radiation ,Plant science ,Environmental science ,Radiation imaging ,Remote sensing - Published
- 2019
20. Plastic Scintillators Enable Live Imaging of 32P-labelled Phosphorus Movement in Large Plants
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Kohei Sugahara, Tomoko M. Nakanishi, Natsuko I. Kobayashi, Atsushi Hirose, Ryohei Sugita, Masaaki Sensui, Etsuko Furuta, and Keitaro Tanoi
- Subjects
Radiation ,chemistry ,Live cell imaging ,Phosphorus ,Radiochemistry ,chemistry.chemical_element ,Environmental science ,Scintillator - Published
- 2019
21. Vertical Migration of 137Cs in Japanese Orchards after the Fukushima Daiichi Nuclear Power Plant Accident
- Author
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Katsuhiko Yamaguchi, Natsuko I. Kobayashi, Tsutomu Ohtsuki, Daisuke Takata, Tsugiko Takase, Shinnosuke Kusaba, Mamoru Sato, Keitaro Tanoi, H. Kikunaga, and Kaori Matsuoka
- Subjects
Fukushima daiichi ,law ,Environmental protection ,Nuclear power plant ,Environmental science ,Plant Science ,Horticulture ,Diel vertical migration ,law.invention - Published
- 2019
22. Optimal Distribution of Iron to Sink Organs via Autophagy Is Important for Tolerance to Excess Zinc in Arabidopsis
- Author
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Kohki Yoshimoto, Daiki Shinozaki, and Keitaro Tanoi
- Subjects
Chlorophyll ,Physiology ,Iron ,ATG5 ,Arabidopsis ,chemistry.chemical_element ,Plant Science ,Zinc ,Gene Expression Regulation, Plant ,Stress, Physiological ,Autophagy ,Arabidopsis thaliana ,Chlorosis ,biology ,Chemistry ,food and beverages ,Cell Biology ,General Medicine ,Iron Deficiencies ,Meristem ,biology.organism_classification ,Cell biology ,Plant Leaves ,Sink (computing) ,Reactive Oxygen Species - Abstract
Zinc (Zn) is nutritionally an essential metal element, but excess Zn in the environment is toxic to plants. Autophagy is a major pathway responsible for intracellular degradation. Here, we demonstrate the important role of autophagy in adaptation to excess Zn stress. We found that autophagy-defective Arabidopsis thaliana (atg2 and atg5) exhibited marked excess Zn-induced chlorosis and growth defects relative to wild-type (WT). Imaging and biochemical analyses revealed that autophagic activity was elevated under excess Zn. Interestingly, the excess Zn symptoms of atg5 were alleviated by supplementation of high levels of iron (Fe) to the media. Under excess Zn, in atg5, Fe starvation was especially severe in juvenile true leaves. Consistent with this, accumulation levels of Fe3+ near the shoot apical meristem remarkably reduced in atg5. Furthermore, excision of cotyledons induced severe excess Zn symptoms in WT, similar to those observed in atg5. Our data suggest that Fe3+ supplied from source leaves (cotyledons) via autophagy is distributed to sink leaves (true leaves) to promote healthy growth under excess Zn, revealing a new dimension, the importance of heavy-metal stress responses by the intracellular recycling.
- Published
- 2020
23. Visualization of seasonal phosphorus re-translocation, and expression profile of phosphate transporters in a shortened annual cycle system of the deciduous poplar tree
- Author
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Miwa Ohnishi, Atsushi J. Nagano, Tomoko M. Nakanishi, Kimitsune Ishizaki, Tetsuro Mimura, Satomi Kanno, Ayumi Deguchi, Kei'ichi Baba, Ayumi Tezuka, Ryohei Sugita, Yuko Kurita, Hidehiro Fukaki, Keitaro Tanoi, and Atsushi Hirose
- Subjects
Deciduous ,chemistry ,Perennial plant ,Phenology ,Phosphorus ,Shoot ,Botany ,Xylem ,chemistry.chemical_element ,Dormancy ,Phloem ,Biology - Abstract
Phosphorus (P) is an essential macronutrient for plant growth. In deciduous trees, P is remobilized from senescing leaves and stored in perennial tissues during winter for further growth. Annual internal recycling and accumulation of P is considered an important strategy to support vigorous growth of trees. However, the pathways of seasonal re-translocation of P and the molecular mechanisms of this transport have not been clarified. Here we show the seasonal P re-translocation route visualized using the real-time radioisotope imaging and the macro- and micro-autoradiography. We analyzed the seasonal re-translocation P in poplar (Populus alba. L) cultivated under “a shortened annual cycle system”, which mimicked seasonal phenology in a laboratory. From growing to senescing season, sink tissues of 32P and/or 33P shifted from young leaves and the apex to the lower stem and roots. The radioisotope P re-translocated from a leaf was stored in phloem and xylem parenchyma cells and redistributed to new shoots after dormancy. Seasonal expression profile of phosphate transporters (PHT1, PHT5 and PHO1 family) was obtained in the same system. Our results reveal the seasonal P re-translocation routes at the organ and tissue levels and provide a foothold for elucidating its molecular mechanisms.
- Published
- 2020
24. Seasonal changes in radiocesium and potassium concentrations in current-year shoots of saplings of three tree species in Fukushima, Japan
- Author
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Satoru Miura, Tanaka Kenzo, Keitaro Tanoi, Takuya Kajimoto, Satoshi Saito, and Natsuko I. Kobayashi
- Subjects
010504 meteorology & atmospheric sciences ,Health, Toxicology and Mutagenesis ,Potassium ,Cryptomeria ,Growing season ,chemistry.chemical_element ,010501 environmental sciences ,Quercus serrata ,01 natural sciences ,Trees ,Coppicing ,Pinus densiflora ,Dry weight ,Japan ,Radiation Monitoring ,Environmental Chemistry ,Fukushima Nuclear Accident ,Waste Management and Disposal ,0105 earth and related environmental sciences ,biology ,General Medicine ,biology.organism_classification ,Pollution ,Plant Leaves ,Horticulture ,chemistry ,Cesium Radioisotopes ,Shoot ,Seasons - Abstract
We studied seasonal changes in radiocesium (137Cs) activity and potassium concentrations in current-year leaves and branches of Pinus densiflora (naturally regenerated saplings), Cryptomeria japonica (planted saplings) and Quercus serrata (planted saplings and coppice shoots) in Fukushima, Japan. We collected current-year shoots from 10 individuals of each species over two growing seasons at intervals of 1-4 months, between June 2016 and December 2017. For the deciduous species Q. serrata, we also collected dead leaves that remained attached to branches in December to investigate reabsorption of 137Cs. All collected shoots were divided into leaves and branches, oven-dried, and ground; dry weights of each sample were recorded. 137Cs activity concentrations were measured using a germanium semiconductor detector. Potassium concentrations were quantified using inductively coupled plasma optical emission spectrometry (ICP-OES). Increases in dry weight were observed in both leaves and branches between May/June and August; growth then slowed considerably and virtually ceased after October. Clear seasonal changes in 137Cs activity concentrations were observed in both 2016 and 2017, regardless of tree species. Concentrations were higher in young leaves and branches during May and June, then decreased and changed relatively little from August to winter. Reduced 137Cs activity concentrations in dead leaves of Q. serrata were observed only in December 2017 (approximately 15% lower than in October). This reduction may indicate reabsorption of 137Cs in leaves prior to shedding. The changes in potassium concentrations were similar to those in 137Cs in both years. Potassium concentrations were higher in young leaves than in mature leaf and branch samples collected later in the year. A reduction of about 50% in the potassium concentrations in dead leaves of Q. serrata was also observed in December. A positive relationship between 137Cs and potassium concentrations in leaves and branches was observed in all species, except for planted Q. serrata. This relationship may indicate that 137Cs moves in tree shoots with potassium. Leaf and branch weight correlated negatively with 137Cs and potassium concentrations. Reduced concentrations may indicate dilution of these elements as a result of biomass increases over the growing season. Our results imply that irrespective of species, 137Cs exhibits seasonal variations resulting from dilution; these variations correspond with trends in potassium, with higher levels in young organs and decreased levels in older organs.
- Published
- 2020
25. Transfer of radiocesium from the upper part of rice plants after treatment at different growth stages
- Author
-
Daisuke Takata, Yoshimi Ohmae, Natsuko Kobayashi, Tomoko M. Nakanishi, Keitaro Tanoi, Atsushi Hirose, and Naoto Nihei
- Subjects
Chemistry ,Health, Toxicology and Mutagenesis ,Public Health, Environmental and Occupational Health ,010501 environmental sciences ,Grain filling ,010403 inorganic & nuclear chemistry ,01 natural sciences ,Pollution ,Husk ,0104 chemical sciences ,Analytical Chemistry ,Horticulture ,Nuclear Energy and Engineering ,Radiology, Nuclear Medicine and imaging ,Brown rice ,Rice plant ,Spectroscopy ,After treatment ,0105 earth and related environmental sciences - Abstract
This study investigated the effect of Cs-137 absorbed from the upper part (surface of leaves and husk) of rice plants and its accumulation in grains. Cesium-137 content in brown rice plants sprayed with Cs-137 onto the plant surface before ear emergence, flowering, and grain filling stages were 5, 109, and 76 Bq/kg, respectively. Comparison of Cs-137 concentration between mature and immature grains revealed that brown rice can easily absorb Cs-137 at the beginning of grain filling.
- Published
- 2018
26. Visualization of 14CO2 gas fixation by plants
- Author
-
Natsuko I. Kobayashi, Tomoko M. Nakanishi, Keitaro Tanoi, and Ryohei Sugita
- Subjects
0106 biological sciences ,Fixation (alchemy) ,Health, Toxicology and Mutagenesis ,010403 inorganic & nuclear chemistry ,Photosynthesis ,01 natural sciences ,Article ,Orientation of photosynthate movement ,Analytical Chemistry ,chemistry.chemical_compound ,Magnoliopsida ,Radiology, Nuclear Medicine and imaging ,Real-time radioisotope imaging system ,Spectroscopy ,biology ,Chemistry ,Carbon fixation ,Public Health, Environmental and Occupational Health ,biology.organism_classification ,Pollution ,0104 chemical sciences ,Horticulture ,Point of delivery ,Nuclear Energy and Engineering ,Isotopes of carbon ,Carbon dioxide ,14CO2 gas ,Carbon-14 ,Soybean ,010606 plant biology & botany - Abstract
Using the real-time radioisotope imaging system (RRIS), we present the carbon dioxide gas fixation process of a soybean plant applying the 14C-labeled gas. When 14CO2 gas was supplied to the selected mature leaf, the fixed carbon, photosynthate, was transferred and accumulated to the younger leaves preferentially within 24 h. When 14CO2 gas was supplied to the younger leaves, fixed carbon was hardly moved. In the case of the pods, fixed 14CO2 gas in the leaf was preferentially transferred to the closest pod.
- Published
- 2018
27. Evaluation of plastic scintillators for live imaging of 14C-labeled photosynthate movement in plants
- Author
-
Etsuko Furuta, Ryohei Sugita, Tomoko M. Nakanishi, Masaaki Sensui, Atsushi Hirose, Keitaro Tanoi, Natsuko I. Kobayashi, and Kohei Sugahara
- Subjects
0106 biological sciences ,Light nucleus ,Materials science ,business.industry ,Health, Toxicology and Mutagenesis ,Public Health, Environmental and Occupational Health ,Scintillator ,010403 inorganic & nuclear chemistry ,01 natural sciences ,Pollution ,0104 chemical sciences ,Analytical Chemistry ,Optics ,Nuclear Energy and Engineering ,Live cell imaging ,Radiology, Nuclear Medicine and imaging ,A fibers ,business ,Spectroscopy ,010606 plant biology & botany - Abstract
We updated real-time radioisotope imaging system (RRIS) to study photosynthate movement in a large-size plant. Earlier, we used a CsI (Tl) scintillator attached to a fiber optic plate (FOS) to convert radiation into light. However, the scintillator size was fixed as 10 cm × 10 cm, which was too small to observe the entire plant. Moreover, the high cost of FOS makes it hard for other researchers to introduce the system in their facilities. Here, we investigated six types of low-priced plastic scintillators, and demonstrated the movement of 14C-labeled photosynthates in a living plant using the most efficient scintillator instead of FOS.
- Published
- 2018
28. Secondary radiocesium contamination of agricultural products by resuspended matter
- Author
-
Kazuya Yoshimura, Taiga Okumura, Keitaro Tanoi, Toshihiro Kogure, Naoto Nihei, Tomoko M. Nakanishi, and Kazuki Iijima
- Subjects
0301 basic medicine ,biology ,business.industry ,Health, Toxicology and Mutagenesis ,Public Health, Environmental and Occupational Health ,Particle (ecology) ,Contamination ,010403 inorganic & nuclear chemistry ,biology.organism_classification ,01 natural sciences ,Pollution ,0104 chemical sciences ,Analytical Chemistry ,03 medical and health sciences ,030104 developmental biology ,Nuclear Energy and Engineering ,Agriculture ,Environmental chemistry ,Environmental science ,Spinach ,Radiology, Nuclear Medicine and imaging ,business ,Spectroscopy - Abstract
Contamination of agricultural products by resuspended matter remains a concern in the highly contaminated areas. Radiocesium concentration of spinach cultivated with non-contaminated soil was low in the decontaminated areas, but high in the contaminated areas. The washed plants had relatively lower radiocesium concentration than the unwashed plants. Furthermore, the plants cultivated closer to the ground surface tended to have a higher radiocesium concentration than those cultivated farther from the ground. Therefore, it can be concluded that radiocesium found in the spinach leaves derived from resuspended matter in the air. With further analysis, radiocesium in the resuspended matter was confirmed to be present as particles.
- Published
- 2018
29. Quantification of dissolved and particulate radiocesium fluxes in two rivers draining the main radioactive pollution plume in Fukushima, Japan (2013–2016)
- Author
-
Takahiro Tatsuno, Taku Nishimura, Keitaro Tanoi, Masaru Mizogichi, Yui Nonaka, Hiroyuki Matsui, and Kazutoshi Osawa
- Subjects
Hydrology ,Global and Planetary Change ,Radionuclide ,Ecology ,Radioactive waste ,Sediment ,Human decontamination ,010501 environmental sciences ,Particulates ,010403 inorganic & nuclear chemistry ,01 natural sciences ,River water ,0104 chemical sciences ,Plume ,Fukushima daiichi ,Earth and Planetary Sciences (miscellaneous) ,Environmental science ,0105 earth and related environmental sciences - Abstract
Radionuclides released by the accident at the Fukushima Daiichi Nuclear Power Plant included 137Cs (Cesium-137) and 134Cs (Cesium-134), which were deposited on land as a result of fallout and concentrated in the uppermost 2–5 cm of the soil. In this study, river monitoring was conducted for 3.5 years to quantify dissolved and particulate radiocesium fluxes in the Mano and Hiso Rivers in Fukushima Prefecture from 2013 to 2016. Total 137Cs export was estimated to be 191 GBq from the Hiso River and 26 GBq from the Mano River during the 3.5-year study. Annual particulate 137Cs export during rainfall events accounted for 90–98% of total 137Cs export. Annual dissolved 137Cs export during rainfall events accounted for 1.5–3.3% of total export. The annual sum of particulate and dissolved 137Cs exports during low-flow periods accounted for 0.6–6.5% of total export. Hence, radiocesium was redistributed mainly by transport of particulate radiocesium bound to suspended sediments. During the study period, 0.7% and 0.6% of the 137Cs initially deposited on soil were exported by the Hiso River and Mano River, respectively. The slopes of regression lines relating fine suspended sediment concentrations and particulate 137Cs concentrations in river water declined from 2013 to 2016 by 79% for the Hiso River and 83% for the Mano River. Especially noteworthy was a sharp decrease of the annual mean 137Cs concentration of SS in 2016. This decrease was much greater than the decrease that would have been expected from the physical decay of 137Cs and was probably related to changes of soil erosion processes due to heavy rainfall and the effects of decontamination efforts in 2015.
- Published
- 2018
30. Magnesium deficiency damages the youngest mature leaf in rice through tissue-specific iron toxicity
- Author
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Natsuko I. Kobayashi, Tomoko M. Nakanishi, Keitaro Tanoi, Ren Iwata, Takaaki Ogura, Ryohei Sugita, Keiko Takagi, and Hisashi Suzuki
- Subjects
0106 biological sciences ,0301 basic medicine ,Senescence ,Chemistry ,Soil Science ,Plant physiology ,Plant Science ,Vacuole ,Photosynthesis ,medicine.disease_cause ,01 natural sciences ,Cell biology ,Transcriptome ,03 medical and health sciences ,030104 developmental biology ,Downregulation and upregulation ,Gene expression ,medicine ,Oxidative stress ,010606 plant biology & botany - Abstract
Magnesium deficiency can cause starch accumulation, photosynthesis inhibition and senescence particularly in young mature leaves. This study was performed to identify the initial process leading to leaf senescence under Mg deficiency. Gene expression in the young leaf was analyzed at days 2, 4, 5 of Mg deficiency using microarray analysis, and several Fe responsive genes were identified. Therefore, the effect of lowering Fe supply on gene expression and oxidative stress under Mg deficiency was evaluated. Transcriptome analysis revealed that 7 of the 30 most upregulated genes and 11 of the 30 most downregulated genes were Fe-responsive. Particularly, the upregulation of OsFER2 and downregulation of OsMIR and OsIRO2 hinted at the induction of excess Fe stress under Mg deficiency. Both lowering of Fe concentration in Mg-free solutions and resupply of Mg without modifying Fe concentrations at day 4 rescued leaves from senescence by inhibiting oxidative stress and normalising the expression of Fe-responsive genes. Meanwhile, Fe content was equal between control, Mg-deficient and Mg-resupplied plants. Mg shortage can induce excess Fe stress, which in turn causes oxidative stress before inhibition of photosynthesis. It is proposed that Mg deficiency disrupts a mechanism for storing toxic Fe ions into the vacuole in the expanding young leaf cells.
- Published
- 2018
31. Studying 137Cs dynamics during litter decomposition in three forest types in the vicinity of Fukushima Dai-ichi Nuclear Power Plant
- Author
-
Mizue Ohashi, Natsuko I. Kobayashi, Nobuhito Ohte, Atsushi Hirose, Izuki Endo, and Keitaro Tanoi
- Subjects
010504 meteorology & atmospheric sciences ,Ecology ,Forestry ,010501 environmental sciences ,01 natural sciences ,Litter decomposition ,law.invention ,law ,Forest ecology ,Nuclear power plant ,Litter ,Environmental science ,Soil mesofauna ,0105 earth and related environmental sciences - Abstract
To investigate the contribution of soil animals to the cesium-137 (137Cs) concentration change in the course of the litter decomposition process, we conducted litter bag experiments in fore...
- Published
- 2018
32. Effect of different Cs concentrations on overall plant growth and Cs distribution in soybean
- Author
-
Naoto Nihei, Tomoko M. Nakanishi, and Keitaro Tanoi
- Subjects
133Cs ,0106 biological sciences ,Absorption (pharmacology) ,Plant growth ,137Cs ,Potassium ,chemistry.chemical_element ,lcsh:Plant culture ,010403 inorganic & nuclear chemistry ,01 natural sciences ,law.invention ,Magazine ,law ,lcsh:SB1-1110 ,Optical emission spectrometry ,Stable isotope ratio ,fungi ,food and beverages ,0104 chemical sciences ,chemistry ,Environmental chemistry ,Inductively coupled plasma atomic emission spectroscopy ,ICP-OES ,Inductively coupled plasma ,Soybean ,Agronomy and Crop Science ,010606 plant biology & botany - Abstract
The absorption and dynamics of Cs in crops can be measured and examined using not only 137Cs but also 133Cs, a stable isotope which can be analyzed in a regular laboratory. When 133Cs is used, however, the concentration of added 133Cs must be set higher than that in the soil solution due to the detection sensitivity of inductively coupled plasma optical emission spectrometry (ICP-OES). There is concern that such high Cs concentrations may adversely affect crops and interfere with Cs dynamics. Using soybean as a test product, we first examined the initial growth of soybean cultivated under exposure to solutions with different 133Cs concentrations. In combination with each 133Cs concentration, two potassium (K) concentrations were tested. Results show that at both K concentrations, growth was inhibited under 133Cs concentrations higher than 1 × 10−3 mol L−1. Soybeans cultivated at 133Cs concentrations higher than 1 × 10−6 mol L−1 can be subject to ICP-OES for measuring 133Cs concentrations in the plant tissue. Next, soybeans cultivated under different 133Cs concentrations throughout growth were examined for Cs distribution in the plants. The distribution patterns of Cs in soybean plants cultivated at 133Cs concentrations equivalent to those found in the soil were almost identical to those in plants cultivated at measurable 133Cs concentrations (1 × 10−6–1 × 10−4 mol L−1) as measured with ICP-OES. Therefore, in our investigation, 133Cs distribution in soybean plants treated with up to 1 × 10−4 mol L−1 was considered equivalent to that in plants cultivated in the field.
- Published
- 2018
33. Comparative in vivo Imaging of Arsenic and Phosphorus in Pteris vittata Gametophyte by Synchrotron μ-XRF and Radioactive Tracer Techniques
- Author
-
Teruhiko Kashiwabara, Akiko Hokura, Izumi Nakai, Nobuyuki Kitajima, Tomoko M. Nakanishi, Keitaro Tanoi, and Tomoko Abe
- Subjects
Gametophyte ,Radioactive tracer ,biology ,010405 organic chemistry ,Phosphorus ,Radiochemistry ,chemistry.chemical_element ,General Chemistry ,010402 general chemistry ,biology.organism_classification ,01 natural sciences ,Synchrotron ,0104 chemical sciences ,law.invention ,chemistry ,law ,Pteris vittata ,Pteris ,Preclinical imaging ,Arsenic - Abstract
Synchrotron μ-XRF and autoradiography complementally revealed the different behavior of arsenic and phosphorus in Pteris vittata L. at a high spatial resolution in its living state. We found that P...
- Published
- 2019
34. Autoradiography system with phosphor powder (ZnS:Ag) for imaging radioisotope dynamics in a living plant
- Author
-
Takuro Sakai, Yong-Gen Yin, Keisuke Kurita, Nobuo Suzui, Ryohei Sugita, Natsuko I. Kobayashi, Naoki Kawachi, and Keitaro Tanoi
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Chemical engineering ,General Engineering ,General Physics and Astronomy ,Phosphor - Published
- 2021
35. OsHKT1;5 mediates Na + exclusion in the vasculature to protect leaf blades and reproductive tissues from salt toxicity in rice
- Author
-
Hideo Matsumura, Sergey Shabala, Hiroki Ueno, Kaoru Okubo, Tomoaki Horie, Hiroki Yamamoto, Naoki Yamaji, Tomoki Horiuchi, Gynheung An, Natsuko I. Kobayashi, Alex Costa, Mohammad Al Nayef, Jian Feng Ma, Miho Fujii-Kashino, and Keitaro Tanoi
- Subjects
0106 biological sciences ,0301 basic medicine ,Oryza sativa ,fungi ,Mutant ,food and beverages ,Xylem ,Transporter ,[object Object] ,Cell Biology ,Plant Science ,Biology ,Vascular bundle ,01 natural sciences ,Cell biology ,03 medical and health sciences ,030104 developmental biology ,Shoot ,Botany ,Genetics ,Phloem ,Gene ,010606 plant biology & botany - Abstract
Salt tolerance quantitative trait loci analysis of rice has revealed that the SKC1 locus, which is involved in a higher K+ /Na+ ratio in shoots, corresponds to the OsHKT1;5 gene encoding a Na+ -selective transporter. However, physiological roles of OsHKT1;5 in rice exposed to salt stress remain elusive, and no OsHKT1;5 gene disruption mutants have been characterized to date. In this study, we dissected two independent T-DNA insertional OsHKT1;5 mutants. Measurements of ion contents in tissues and 22 Na+ tracer imaging experiments showed that loss-of-function of OsHKT1;5 in salt-stressed rice roots triggers massive Na+ accumulation in shoots. Salt stress-induced increases in the OsHKT1;5 transcript were observed in roots and basal stems, including basal nodes. Immuno-staining using an anti-OsHKT1;5 peptide antibody indicated that OsHKT1;5 is localized in cells adjacent to the xylem in roots. Additionally, direct introduction of 22 Na+ tracer to leaf sheaths also demonstrated the involvement of OsHKT1;5 in xylem Na+ unloading in leaf sheaths. Furthermore, OsHKT1;5 was indicated to be present in the plasma membrane and found to localize also in the phloem of diffuse vascular bundles in basal nodes. Together with the characteristic 22 Na+ allocation in the blade of the developing immature leaf in the mutants, these results suggest a novel function of OsHKT1;5 in mediating Na+ exclusion in the phloem to prevent Na+ transfer to young leaf blades. Our findings further demonstrate that the function of OsHKT1;5 is crucial over growth stages of rice, including the protection of the next generation seeds as well as of vital leaf blades under salt stress.
- Published
- 2017
36. Visualization of how light changes affect ion movement in rice plants using a real-time radioisotope imaging system
- Author
-
Tomoko M. Nakanishi, Atsushi Hirose, Hisashi Suzuki, Ryohei Sugita, Keitaro Tanoi, Natsuko I. Kobayashi, and Ren Iwata
- Subjects
0106 biological sciences ,Water flow ,Chemistry ,Health, Toxicology and Mutagenesis ,Public Health, Environmental and Occupational Health ,Analytical chemistry ,010403 inorganic & nuclear chemistry ,01 natural sciences ,Pollution ,0104 chemical sciences ,Analytical Chemistry ,Ion ,Nuclear Energy and Engineering ,Light Cycle ,Mass transfer ,TRACER ,Radiology, Nuclear Medicine and imaging ,Absorption (electromagnetic radiation) ,Biological system ,Rice plant ,Spectroscopy ,010606 plant biology & botany ,Transpiration - Abstract
We developed a real-time radioisotope imaging system (RRIS) technique that can nondestructively visualize the element absorption and transport process in plants, using not only positron emitters but also commercially available radioisotopes. In this study, we applied RRIS to analyze light effects on ion movement in rice plants. As tracers, 28Mg, 32P, and 45Ca were used. During the first 5 h, dark/light cycle of 3/7 min were set up; the RRIS needs dark conditions during capturing. When the light was ceased 5 h after supplying each tracer, 32P transport from root to shoot decreased immediately. In contrast, 28Mg and 45Ca transport did not change with light conditions. These results suggest that the P transport is dependent on water flow, whereas Mg and Ca transport are independent of water flow.
- Published
- 2017
37. The Concentration Distributions of Cs in Soybean Seeds
- Author
-
Tomoko M. Nakanishi, Koji Kita, Atsushi Hirose, Keitaro Tanoi, Akifumi Sugiyama, Naoto Nihei, Yoshiaki Ito, and Takeshi Onji
- Subjects
Thesaurus (information retrieval) ,Radiation ,Information retrieval ,Chemistry ,Radiochemistry ,010501 environmental sciences ,010403 inorganic & nuclear chemistry ,01 natural sciences ,0104 chemical sciences ,0105 earth and related environmental sciences - Published
- 2017
38. PIN FORMED 2 facilitates the transport of Arsenite inArabidopsis thaliana
- Author
-
Olga Antipova, Kotaro Nagatsu, Mohammad Arif Ashraf, Abidur Rahman, Cheyenne D. Kiani, Michiko Saito, Olena Ponomarenko, Kana Umetsu, Karen K. Tanino, Katsuyuki Minegishi, Graham N. George, Christian Luschnig, Susan Nezhati, Takehiro Kamiya, Ingrid J. Pickering, Mohammad Aslam, Toru Fujiwara, Natalia V. Dolgova, and Keitaro Tanoi
- Subjects
0106 biological sciences ,Auxin efflux ,0303 health sciences ,biology ,Auxin homeostasis ,Chemistry ,Arsenate ,Transporter ,biology.organism_classification ,01 natural sciences ,Cell biology ,03 medical and health sciences ,chemistry.chemical_compound ,Arabidopsis thaliana ,Efflux ,Intracellular ,030304 developmental biology ,010606 plant biology & botany ,Arsenite - Abstract
Arsenic contamination is a major environmental issue as it may lead to serious health hazard. Reduced trivalent form of inorganic arsenic, arsenite, is in general more toxic to plants compared with the fully oxidized pentavalent arsenate. The uptake of arsenite in plants has been shown to be mediated through a large subfamily of plant aquaglyceroporins, nodulin 26-like intrinsic proteins (NIPs). However, the efflux mechanisms, as well as the mechanism of arsenite-induced root growth inhibition, remain poorly understood. Using molecular physiology, synchrotron imaging, and root transport assay approaches, we show that the cellular transport of trivalent arsenicals inArabidopsis thalianais strongly modulated by PIN FORMED 2 (PIN2) auxin efflux transporter. Direct transport assay using radioactive arsenite, X-ray fluorescence imaging (XFI) coupled with X-ray absorption spectroscopy (XAS), and ICP-MS analysis revealed thatpin2plants accumulate higher concentrations of arsenite in root compared to wild-type. At the cellular level, arsenite specifically targets intracellular cycling of PIN2 and thereby alters the cellular auxin homeostasis. Consistently, loss of PIN2 results in aresenite hypersensitivity in root. XFI coupled with XAS further revealed that loss of PIN2 results in specific accumulation of arsenical species, but not the other metals like iron, zinc or calcium in the root tip. Collectively, these results demonstrate that PIN2 serves as a putative transporter of arsenical speciesin planta.
- Published
- 2019
39. Agricultural Implications of the Fukushima Nuclear Accident (III)
- Author
-
Keitaro Tanoi, Martin O Brien, and Tomoko M. Nakanishi
- Subjects
Pollution ,Fukushima Nuclear Accident ,Environmental remediation ,business.industry ,media_common.quotation_subject ,Contamination ,Nuclear power ,Environmental protection ,Agricultural land ,Radioactive contamination ,Forest ecology ,Environmental science ,business ,media_common - Abstract
An Overview of Our Research.- Transfer of Radiocesium to Rice in Contaminated Paddy Fields.- Cesium Translocation in Rice.- Absorption of radioceasium in soybean.- An observational study of pigs exposed to radiation.- A Composting System to Decompose Radiocesium Contaminated Baled Grass Silage.- Weathered Biotite: A Key Material of Radioactive Contamination in Fukushima.- Radiocesium accumulation in koshiabura (Eleutherococcus sciadophylloides) and other wild vegetables and in Fukushima Prefecture.- The Transition of Radiocesium in Peach Trees After the Fukushima Nuclear Accident.- Application of the Artificial Annual Environmental Cycle and Dormancy-induced Suppression of Cesium Uptake in Poplar.- Radiocesium Contamination in Forests and the Current Situation of Growing Oak Trees for Mushroom Logs.- Radiocesium Dynamics in Wild Mushrooms During the First Five Years After the Fukushima Accident.- The Spatial Distribution of Radiocesium Over a Four-year Period in a Forest Ecosystem in North Fukushima After the Nuclear Power Station Accident.- Parallel Measurement of Ambient and Individual External Radiation in Iitate Village, Fukushima.- Mobility of Fallout Radiocesium Depending on the Land Use in Kasumigaura Basin.- Challenges of Agricultural Land Remediation and Renewal of Agriculture in Iitate Village by a Collaboration Between Researchers and a Non-profit Organization.- Radiocesium Contamination on a University Campus and in Forests in Kashiwa City, Chiba Prefecture, a Suburb of Metropolitan Tokyo.- The State of Fisheries and Marine Species in Fukushima: Six Years After the 2011 Disaster.- Visualization of Ion Transport in Plants.- 90Sr analysis using inductively coupled plasma mass spectrometry with split-flow injection and online solid-phase extraction for multiple concentration and separation steps.
- Published
- 2019
40. Cesium Translocation in Rice
- Author
-
Natsuko I. Kobayashi, Shuto Shiomi, Tatsuya Nobori, Nathalie Leonhardt, Keitaro Tanoi, Tomoko M. Nakanishi, and Takumi Saito
- Subjects
Tracer experiment ,Agronomy ,chemistry ,Caesium ,fungi ,Molecular mechanism ,food and beverages ,chemistry.chemical_element ,Chromosomal translocation ,Brown rice ,Cultivar - Abstract
To breed a low Cs rice variety, it is important to clarify the mechanism of Cs transport in a plant. In the present report, we found a difference in Cs distribution in rice cultivars using a 137Cs tracer experiment. In addition, the difference was also found in Cs distribution of each leaf position among the same rice cultivars. There has been no report clarifying the molecular mechanism of Cs translocation, nor those of other cations, in plants. Using the rice cultivars, Akihikari and Milyang23, to find the Cs translocation mechanism can contribute to developing crops that contain lower levels of Cs when cultivated in radiocesium contaminated land.
- Published
- 2019
41. An Observational Study of Pigs Exposed to Radiation
- Author
-
Keitaro Tanoi, Chunxiang Piao, Natsuko Kobayashi, Tomotsugu Takahashi, Junyou Li, Atsushi Hirose, Masayoshi Kuwahara, Hirohiko Iitsuka, Tomoko M. Nakanishi, and Masanori Ikeda
- Subjects
Fukushima daiichi ,Animal science ,Nuclear disaster ,Animal resource ,Biology - Abstract
On June 28, 2011, 26 pigs were rescued from the alert area, 17 km northwest of the Fukushima Daiichi Nuclear Power Plant, where radiation levels were approximately 1.9–3.8 μSv/h. The pigs were transferred outside of the radiation alert area to the Animal Resource Science Center (ARSC), The University of Tokyo. It was confirmed by the farm owner that the pigs were never fed radiation-contaminated concentrate and they had access to uncontaminated groundwater (http://www.env.go.jp/press/press.php?serial=16323) while living inside the radiation alert area; however, radiocesium was detected in the rescued pigs’ organs, testis/ovary, spleen, liver, kidney, psoas major, urine, and blood, within nine months after the nuclear disaster. Radiocesium levels in samples collected in early January 2012 were significantly lower than those collected in either early or late September 2011, indicating a continuing decrease in radiation levels over that duration. Radiocesium was not detected in organs collected in August 2012. In September 2011, the authors of the present study visited a local farm to collect samples from pigs who remained inside the radiation alert area. Radiocesium concentration in these pigs was nearly ten times higher than from the rescued pigs.
- Published
- 2019
42. Agriculture in Fukushima: Radiocesium Contamination of Agricultural Products
- Author
-
Martin O'Brien, Keitaro Tanoi, and Naoto Nihei
- Subjects
Agriculture ,business.industry ,Environmental protection ,Monitoring data ,Environmental science ,Contamination ,Arable land ,business ,Food safety - Abstract
In this study, we examine the radioactivity monitoring data derived from Fukushima prefecture. The Japanese government has established very strict limits for radiocesium in food since April 2012 (100 Bq/kg for general food). The Fukushima prefectural government inspected foods and found that most of the agricultural products in Fukushima did not contain contamination above the laboratory detection limit. Moreover, the radiocesium concentration in food samples decreased over time for the first 2–5 years, and very few samples of forest products, marine, and lake products exceeded the limit 5 years after the accident. Potassium fertilization of arable land has been the most effective countermeasure, and the effort to create crops with low levels of cesium is continuing.
- Published
- 2019
43. The Spatial Distribution of Radiocesium Over a Four-Year Period in a Forest Ecosystem in North Fukushima After the Nuclear Power Station Accident
- Author
-
Masashi Murakami, Nobuyoshi Ishii, Nobuhito Ohte, Keitaro Tanoi, Takahiro Miyata, and Natsuko Kobayashi
- Subjects
Hydrology ,Forest floor ,geography ,geography.geographical_feature_category ,business.industry ,Drainage basin ,Nuclear power ,Spatial distribution ,Catchment scale ,Forest ecology ,Soil water ,Environmental science ,Ecosystem ,business - Abstract
We have investigated the redistribution dynamics of radiocesium deposited after the nuclear power station accident in March 2011 in a forested catchment located in North Fukushima over a four-year period (2012–2015). At the catchment scale, 137 Cs accumulation decreased drastically by 50% of the estimated initial accumulation during the first 2 years. Cs-137 accumulation in the forest floor occurred in the litter layers and the surface part of mineral soils and have accounted for about 90% of the total catchment scale accumulation. The internal 137Cs cycle among the soil-plant system was also identified as a retention mechanism and was biologically dynamic. Monitoring the decreasing and retaining mechanisms of radioactivity at the ecosystem scale will be required for effective forest and water resource management.
- Published
- 2019
44. Visualization of Ion Transport in Plants
- Author
-
Atsushi Hirose, Tomoko M. Nakanishi, Keitaro Tanoi, Natsuko I. Kobayashi, and Ryohei Sugita
- Subjects
Absorption (pharmacology) ,Magnesium ,Potassium ,fungi ,food and beverages ,chemistry.chemical_element ,Calcium ,Phosphate ,Ion ,chemistry.chemical_compound ,chemistry ,Environmental chemistry ,Shoot ,Ion transporter - Abstract
We have developed a real-time radioisotope imaging system (RRIS) to visualize ion transport in plants, and to measure radioactivity in living plants. To know the mechanisms of ion transport in plants, the use of living plants allows us to visualize ion movement in real time. In addition, the RRIS can analyze how a change to the plant environment affects ion transport. In this chapter, we will introduce some of the applications of the RRIS. We analyzed the effect of light on cesium, potassium, magnesium, phosphate, and calcium transport in plants using the RRIS. The results show that magnesium, potassium, and calcium transport in plants were not influenced by light. On the other hand, the amount of cesium and phosphate absorption in roots decreased after light-off. Moreover, the amount of phosphate transport from root to shoot also decreased after light-off.
- Published
- 2019
45. Desorption mechanisms of cesium from illite and vermiculite
- Author
-
Satoshi Utsunomiya, Asumi Ochiai, Kento Murota, Keitaro Tanoi, and Takumi Saito
- Subjects
chemistry.chemical_classification ,Prussian blue ,Sorbent ,Inorganic chemistry ,Salt (chemistry) ,chemistry.chemical_element ,Sorption ,010501 environmental sciences ,Vermiculite ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Pollution ,chemistry.chemical_compound ,chemistry ,Geochemistry and Petrology ,Desorption ,Caesium ,Illite ,engineering ,Environmental Chemistry ,0105 earth and related environmental sciences - Abstract
It is known that cesium ion, Cs+, is strongly sorbed to micaceous minerals. However, the desorption of Cs+ at a trace sorption level with time in the presence of different salt ions is not well understood. In this study, we conducted long-term sorption and desorption experiments of Cs+ with illite and vermiculite at room temperature to study the effects of sorption time and co-existing cations on the desorption. A small amount of Cs+ (50 nM Cs+ spiked with 900 Bq 137Cs) was sorbed to the illite and vermiculite in the presence of 1 mM K+ or Ca2+, or 1 mM K+ and 100 mM Ca2+ over 8 weeks, which was then desorbed in the presence of Prussian blue (PB) nanoparticles over 12 weeks. The PB nanoparticles were used to inhibit the re-sorption of desorbed Cs+. More than 90% of Cs+ was sorbed to the minerals in the presence of Ca2+; meanwhile, only 50–70% of Cs+ was in the presence of K+. For all samples other than the illite with Ca2+ (Ca-illite), more than 80% of Cs+ were desorbed within a few days, and almost all Cs+ was desorbed at the end of the experiment. The large and fast desorption of Cs+ indicated a large part of Cs+ sorbed to these minerals were indeed labile in the presence of a strong sorbent like PB nanoparticles. These desorption trends were hardly influenced by a change of the sorption time. The desorption of Cs+ from the Ca-illite was slow, taking more than one month before 80% desorption for the sample with 1-day sorption, and the desorption amount only reached less than 90%. This slow desorption of Cs+ from the Ca-illite became even slower with the sorption time from one day to two weeks, and only 70% of sorbed Cs+ was desorbed at the end of the experiment for the latter. The mechanisms of Cs+ desorption from the Ca-illite was quantitatively explained by fitting to a pseudo first-order desorption model, suggesting that 30–40% of Cs+ was sorbed to the peripheral region of the interlayer of the Ca-illite and diffused into the interior part. The rest of sorbed Cs+ can be desorbed relatively fast. As this Cs+ was most likely sorbed to frayed edge sites in the Ca-illite, these results suggested that a part of the sorbed Cs+ (70 - 60%) was labile. Thus, the expansion and collapse of the peripheral regions of the interlayers induced by co-existing cations and interlayer migration of Cs+ are important processes constraining the sorption and desorption of Cs+ to/from the micaceous minerals. In addition, compared with the desorption from the pure minerals examined in this study, the desorption of Cs+ from real soils was slower likely due to weathering and/or the formation of aggregates.
- Published
- 2020
46. Effect of the application of polluted wheat (Triticum aestivumL. Thell.) straw during plowing on the transfer of radiocesium from the soil to komatsuna (Brassica rapaL. var.perviridis)
- Author
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Toshihumi Murakami, Nobuo Yamashita, Naoto Nihei, Sho Morimoto, Shigeto Fujimura, Keitaro Tanoi, and Tomoko M. Nakanishi
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chemistry.chemical_classification ,business.product_category ,Soil Science ,Plant Science ,010501 environmental sciences ,Contamination ,Straw ,010403 inorganic & nuclear chemistry ,01 natural sciences ,0104 chemical sciences ,Andosol ,Plough ,Fukushima daiichi ,Agronomy ,chemistry ,Brassica rapa ,Environmental science ,Organic matter ,business ,0105 earth and related environmental sciences - Abstract
Radioactive substances were released into the environment after the nuclear accident at the Fukushima Daiichi Nuclear Power Station; this led to the contamination of the soil at Fukushima Prefecture. Mixing of organic matter with soil during plowing is known to influence radiocesium (134Cs and 137Cs) absorption by crops. However, the effect of mixing organic matter polluted by radioactive substances during plowing on radiocesium absorption by plants is not yet known. The aim of this study was to investigate the effect on the radiocesium absorption by komatsuna (Brassica rapa L. var. perviridis) cultivated in a 45-L container containing Andosol (14,300 Bq kg−1) or Gray Lowland soil (33,500 Bq kg−1) mixed with polluted wheat (Triticum aestivum L. Thell.) straw (2080 Bq kg−1). The radiocesium concentration of the plants and the soil and the amount of exchangeable radiocesium in the soil were determined using a germanium semiconductor. The transfer of radiocesium from the soil to plants decreased by 5...
- Published
- 2016
- Full Text
- View/download PDF
47. Leaf Senescence by Magnesium Deficiency
- Author
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Keitaro Tanoi and Natsuko I. Kobayashi
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Senescence ,Chlorosis ,Ecology ,leaf senescence ,Metabolite ,Botany ,Review ,magnesium deficiency ,Plant Science ,Biology ,medicine.disease_cause ,Plant cell ,Photosynthesis ,transpiration ,chemistry.chemical_compound ,Biochemistry ,chemistry ,QK1-989 ,medicine ,Magnesium ion ,Ecology, Evolution, Behavior and Systematics ,Oxidative stress ,Transpiration - Abstract
Magnesium ions (Mg(2+)) are the second most abundant cations in living plant cells, and they are involved in various functions, including photosynthesis, enzyme catalysis, and nucleic acid synthesis. Low availability of Mg(2+) in an agricultural field leads to a decrease in yield, which follows the appearance of Mg-deficient symptoms such as chlorosis, necrotic spots on the leaves, and droop. During the last decade, a variety of physiological and molecular responses to Mg(2+) deficiency that potentially link to leaf senescence have been recognized, allowing us to reconsider the mechanisms of Mg(2+) deficiency. This review focuses on the current knowledge about the physiological responses to Mg(2+) deficiency including a decline in transpiration, accumulation of sugars and starch in source leaves, change in redox states, increased oxidative stress, metabolite alterations, and a decline in photosynthetic activity. In addition, we refer to the molecular responses that are thought to be related to leaf senescence. With these current data, we give an overview of leaf senescence induced by Mg deficiency.
- Published
- 2015
48. Monitoring free-living Japanese Bush Warblers (Cettia diphone) in a most highly radiocontaminated area of Fukushima Prefecture, Japan
- Author
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Tomoko M. Nakanishi, Ken Ishida, and Keitaro Tanoi
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Male ,0106 biological sciences ,0301 basic medicine ,Fukushima Nuclear Accident ,Health, Toxicology and Mutagenesis ,Special Issue - Fukushima ,Wildlife ,microhabitat radiation heterogeneity ,Radiation Dosage ,01 natural sciences ,010605 ornithology ,Birds ,03 medical and health sciences ,Cloaca ,Japan ,Bush-warbler ,Animals ,Radiology, Nuclear Medicine and imaging ,Wildlife conservation ,Radiation ,biology ,biology.organism_classification ,Abukuma highland ,Fishery ,030104 developmental biology ,Geography ,Feather ,visual_art ,Cettia diphone ,visual_art.visual_art_medium ,ecology ,Bush Warbler ,contingence ,Radioactive Pollutants - Abstract
The Fukushima-Daiichi Nuclear Power Plant (F1NPP) accident is an IAEA level 7 event, the same as that of Chernobyl, while the amount of radionuclides released is not comparable. Radioactivity attributed to the F1NPP accident was detected 250 km away from the F1NPP. Although we have not yet systematically studied the effect of radionuclides on the environment and wildlife, one of three Japanese Bush Warblers (Cettia diphone), captured in Akaugi district in August 2011, was observed to have a conspicuous lesion near the cloaca, which is rare in Japan. All of the birds' feathers were strongly contaminated. Further study is needed to determine the significance of this result. We emphasize the importance of continuing assessment of the effects of the F1NPP accident on wildlife.
- Published
- 2015
49. Radiocesium transfer rates among pigs fed haylage contaminated with low levels of cesium at two differentiation stages
- Author
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Min Ma, Atsushi Hirose, Masayoshi Kuwahara, Chunxiang Piao, Junyou Li, Masanori Ikeda, Kazuyuki Uchida, Natsuko I. Kobayashi, James K. Chambers, and Keitaro Tanoi
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Swine ,Physiology ,Administration, Oral ,Cesium ,lcsh:Medicine ,Urine ,Kidney ,Pig Models ,Medicine and Health Sciences ,Femur ,lcsh:Science ,Musculoskeletal System ,Mammals ,Multidisciplinary ,Thyroid ,Eukaryota ,Hematology ,Animal Models ,Contamination ,Body Fluids ,Chemistry ,Blood ,medicine.anatomical_structure ,Liver ,Experimental Organism Systems ,Physiological Parameters ,Cesium Radioisotopes ,Vertebrates ,Physical Sciences ,Medicine ,Anatomy ,Research Article ,Chemical Elements ,Science ,Spleen ,Biology ,Research and Analysis Methods ,Body weight ,Animal science ,medicine ,Animals ,Juvenile ,Food Contamination, Radioactive ,Skeleton ,Body Weight ,lcsh:R ,Organisms ,Biology and Life Sciences ,Kidney metabolism ,Kidneys ,Renal System ,Amniotes ,Animal Studies ,lcsh:Q ,Zoology ,Food contaminant - Abstract
The objective of this study was to determine the radiocesium transfer rates of pigs fed haylage contaminated with low levels of cesium at different growth stages. We measured the body weight of juvenile and adult pigs during the treatment period to confirm their health status. We also performed pig blood hematologic and biochemical analyses at both growth stages. To our knowledge, this is the first study to report pig radiocesium transfer coefficient rates after 1 month of chronic oral treatment, which is the period assumed to be required for body equilibrium under a diet of radiocesium-contaminated food. The results showed higher radiocesium retention rates in the kidneys, liver, spleen, genitals, psoas major, bladder, thyroid, and urine than in the blood and bone (tibia and femur) of pigs at both growth stages. The radiocesium retention levels were generally higher in juvenile pigs than in adult pigs, with the highest transfer coefficient ratio in the kidneys (16.2%).
- Published
- 2020
50. Magnesium uptake characteristics in Arabidopsis revealed by
- Author
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Takaaki, Ogura, Natsuko I, Kobayashi, Hisashi, Suzuki, Ren, Iwata, Tomoko M, Nakanishi, and Keitaro, Tanoi
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Isotopes ,Gene Expression Regulation, Plant ,Stress, Physiological ,Arabidopsis ,Biological Transport ,Magnesium ,Plant Roots - Abstract
The Mg
- Published
- 2018
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