Natsuko I Kobayashi

Natsuko I Kobayashi
The University of Tokyo | Todai · Department of Applied Life Sciences

About

85
Publications
11,925
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
1,711
Citations
Citations since 2016
39 Research Items
1502 Citations
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
2016201720182019202020212022050100150200250300
Introduction
I've tried to provide the basis for understanding the behavior of ions in plants and how plants response to the nutritional stress. My experiments can be unique in that several radionuclides are frequently applied as tracers. Understanding the essential features of Mg in plants is the long-term subject of my research. To address the agricultural problems regarding radiocaesium contamination is also my big task.
Additional affiliations
April 2014 - present
The University of Tokyo
Position
  • Research Assistant

Publications

Publications (85)
Article
Full-text available
Tracer experiments using radioisotope are powerful for the analysis of mineral uptake mechanisms in plant roots. In this study, we aimed to establish a quantitative method for measuring ion fluxes, i.e. net flux, influx, and efflux, which can be used to phenotyping of the mutants and natural variations. Consistency of obtained flux values for Mg²⁺...
Article
Magnesium is an important nutrient for plants, but much is still unknown about plant Mg2+ transporters. Combining with the structural prediction of AlphaFold2, we used mutagenesis and 28Mg uptake assay to study the highly conserved “GMN” motif of Arabidopsis thaliana MRS2-1 (AtMRS2-1) transporter. We demonstrated that the glycine and methionine in...
Preprint
Full-text available
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...
Article
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+ uptake 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 p...
Article
This study aimed to investigate the dynamics of ¹³⁷Cs around banks along an agricultural canal for paddy fields in Iitate, Fukushima, Japan. Five plots (2.4–12.6 m²) on the banks were monitored intermittently during six time periods from May 2018 to November 2019. We directly collected runoff water samples discharged from the banks followed by part...
Article
Full-text available
We performed consecutive field trials of rice cultivation to monitor radiocesium contamination in harvested rice from 2012, in the Iitate Village in Fukushima Prefecture, where people were forced to be evacuated due to high level of radioactive contamination caused by the disaster at the Fukushima Dai-ichi Nuclear Power Plant of Tokyo Electric Powe...
Article
Full-text available
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...
Article
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...
Article
Full-text available
Magnesium (Mg) is essential for many biological processes in plant cells, and its deficiency causes yield reduction in crop systems. Low Mg status reportedly affects photosynthesis, sucrose partitioning and biomass allocation. However, earlier physiological responses to Mg deficiency are scarcely described. Here, we report that Mg deficiency in Ara...
Article
Radiocesium contamination of forests has been a severe problem after the Fukushima Daiichi Nuclear Power Plant accident in 2011. Bed logs of Konara oak (Quercus serrata Murray), used for mushroom cultivation, were an economically important product from the forests prior to their contamination. One of the potential countermeasures to reduce radioces...
Article
We updated our imaging system, namely real-time radioisotope imaging system (RRIS) to observe ³²P movement in large plants using a large size scintillator. In the previous version of RRIS, the view was limited by the size of a CsI (Tl) scintillator deposited on a fiber optic plate (FOS). However, owing to the high price and difficulty in handling o...
Article
Full-text available
We investigated the vertical ¹³⁷Cs distribution in soil among five sod culture orchards with different soil textures over six years after 2011, when ¹³⁷Cs fallout was released by the Fukushima Daiichi Nuclear Power Plant accident, to confirm the long-term ¹³⁷Cs downward-migration into soil. At each orchard, soil cores were collected to a depth of 3...
Chapter
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 af...
Chapter
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 r...
Chapter
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 yea...
Chapter
The radiocesium contamination in mushrooms and in mushroom logs is a matter of concern for the forestry industry. To know the contamination situation precisely and the future for mushroom log production, the ¹³⁷Cs distribution in six fields cultivating oak trees in Tamura city, Fukushima, was investigated in 2015. The ¹³⁷Cs concentration in new bra...
Chapter
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 tha...
Article
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-1...
Article
Full-text available
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 sup...
Article
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...
Article
Full-text available
Aims 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. Methods Gene expression in the young leaf was analyzed at days 2, 4, 5 of Mg deficiency using microarray anal...
Article
Main conclusion: The Mg2+ uptake system in Arabidopsis roots is Gd3+- and Fe2+-sensitive, and responds to a changing Mg2+ concentration within 1 h with the participation of AtMRS2 transporters. Magnesium (Mg2+) absorption and the mechanism regulating its activity have not been clarified yet. To address these issues, it is necessary to reveal the c...
Article
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 forest sites located about 50 km northwest from the Fukushima Dai-ichi Nuclear Power Plant. To control the influence of soil animals of different size, two different...
Article
Full-text available
The high affinity K⁺ transporter 1;4 (HKT1;4) in rice (Oryza sativa), which shows Na⁺ selective transport with little K⁺ transport activity, has been suggested to be involved in reducing Na in leaves and stems under salt stress. However, detailed physiological roles of OsHKT1;4 remain unknown. Here, we have characterized a transfer DNA (T-DNA) inse...
Article
Occurrence of radiocesium in food has raised sharp health concerns after nuclear accidents. Despite being present at low concentrations in contaminated soils (below μM), cesium (Cs(+) ) can be taken up by crops and transported to their edible parts. Such a plant capacity to take up Cs(+) from low concentrations has notably affected the production o...
Article
Water deficit caused by global climate changes seriously endangers the survival of organisms and crop productivity, and increases environmental deterioration 1,2. Plants' resistance to drought involves global reprogramming of transcription, cellular metabolism, hormone signalling and chromatin modification 3-8. However, how these regulatory respons...
Article
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...
Article
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, ³²...
Article
Full-text available
Minerals and photosynthates are essential for many plant processes, but their imaging in live plants is difficult. We have developed a method for their live imaging in Arabidopsis using a real-time radioisotope imaging system. When each radioisotope, 22Na, 28Mg, 32P-phosphate, 35S-sulphate, 42K, 45Ca, 54Mn, and 137Cs, was employed as an ion tracer,...
Chapter
To achieve the reduction of the radiocesium content in rice grain, the application of potassium (K) fertilizer to the paddy field is currently recommended. However, physiological basis of the effect of the K addition on the radiocesium accumulation in rice has not been enough provided. Here, the uptake and the distribution of cesium (Cs) in rice pl...
Chapter
Various radioisotope imaging techniques have been used at the Graduate School of Agricultural and Life Sciences, University of Tokyo, to analyze samples containing radiocesium (137Cs and 134Cs). There are two types of samples: (1) environmental samples contaminated by the fallout from the Fukushima Daiichi nuclear power plant accident, which contai...
Chapter
The accident at the Fukushima Daiichi Nuclear Power Plant in March 2011 emitted 1.2 × 1016 Bq of cesium-137 (137Cs) into the surrounding environment. Radioactive substances, including 137Cs, were deposited onto forested areas in the northeastern region of Japan. 137Cs is easily adsorbed onto clay minerals in the soil; thus, a major portion of 137Cs...
Article
Full-text available
Background Na⁺ exclusion from leaf blades is one of the key mechanisms for glycophytes to cope with salinity stress. Certain class I transporters of the high-affinity K⁺ transporter (HKT) family have been demonstrated to mediate leaf blade-Na⁺ exclusion upon salinity stress via Na⁺-selective transport. Multiple HKT1 transporters are known to functi...
Data
Fig. S1 Phostin (PSN) effect on the rice OsPT2 expression. Fig. S2 Effects of Phostin (PSN) structural analogues on the induction of phosphate starvation markers. Fig. S3 Acidic hydrolysis release of Phostin (PSN)11 from the active PSN analogues. Fig. S4 Relative expression level of genes related to the low‐nitrate, low‐sulphur and low‐potassium...
Article
Full-text available
Magnesium ions (Mg2+) 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 Mg2+ in an agricultural field leads to a decrease in yield, which follows the appearance of Mg-deficient symptoms such as chlorosis,...
Article
Full-text available
Magnesium (Mg) is the second most abundant cation in living cells. Over 300 enzymes are known to be Mg-dependent, and changes in the Mg concentration significantly affects the membrane potential. As Mg becomes deficient, starch accumulation and chlorosis, bridged by the generation of reactive oxygen species, are commonly found in Mg-deficient young...
Article
The physiological effects of critical nutrient deficiencies (K, P, N) on the uptake of caesium (Cs) and impact on plant growth has been investigated in rice plants. Growth defects were observed after 2 weeks of a state of nutrient starvation (K, P, or N). However, only K starvation produced increased Cs content in the shoot and the intensive transp...
Article
Full-text available
Plants display numerous strategies to cope with phosphate (Pi)-deficiency. Despite multiple genetic studies, the molecular mechanisms of low-Pi-signalling remain unknown. To validate the interest of chemical genetics to investigate this pathway we discovered and analysed the effects of PHOSTIN (PSN), a drug mimicking Pi-starvation in Arabidopsis. W...
Article
Since the Fukushima Dai-ichi Nuclear Power Plant accident in March 2011, large areas of the forests around Fukushima have become highly contaminated by radioactive nuclides. To predict the future dynamics of radioactive cesium ((137)Cs) in the forest catchment, it is important to measure each component of its movement within the forest. Two years a...
Article
The concentrations of radiocesium in different organs of wild boar inhabiting Iitate, Fukushima were measured, after the Fukushima Daiichi nuclear power plant accident. After dissection, about 24 parts were collected and measured using a NaI gamma ray counter. In 2012, the radiocesium concentration (134Cs and 137Cs) was highest in muscle (approxima...
Article
Full-text available
We investigated the relationship between radiocaesium(134Cs and 137Cs) concentration(specific radio activity:Bq/kg) in rice and the paddy soil in Iitate village where people evacuated because of the high levels of radioactive contamination caused by the Fukushima Daiichi nuclear disaster. The radiocaesium concentration was measured of paddy soil an...
Article
Six months after the explosion of TEPCO's Fukushima Dai-ichi nuclear power plant, radioactive silver ((110m)Ag), was detected in concentrations of 3754 Bq/kg in Nephila clavata (the orb-web spider; Joro-gumo in Japanese) collected at Nimaibashi, Iitate village in Fukushima Prefecture, whereas (110m)Ag in the soil was 43.1 Bq/kg. A survey of 35 faun...
Article
Full-text available
We performed an imaging analysis of 42K in Arabidopsis using real-time radioisotope imaging system(RRIS). First, we purified 42K from an 42Ar―42K generator. And then, we characterized RRIS performance by quantitatively determining 42K using standard series. As a result, the dynamic range for 42K was determined to be at least three orders of magnitu...
Article
Full-text available
The differences in the transport characteristics in planta between potassium (K+) and caesium (Cs+) was investigated using their radionuclides, 42K+ and 137Cs+. A tracer experiment using nutrient solutions supplemented with 42K and 137Cs revealed that the ratio of the root's K+ uptake rate to its Cs+ uptake rate was 7-11 times higher than the K+:Cs...
Article
Arbuscular mycorrhizas support nutrient uptake from the soil. Here we demonstrated Iron-59 (59Fe) uptake in maize (Zea mays L.) through the mycorrhizal roots. Arbuscular mycorrhizal colonization did not strongly induce Strategy II-related genes, but the putative iron transporter genes, OPT8a and OPT8b, were induced by more than 50-fold. Our data pr...
Article
Full-text available
This study investigated the effects of potassium (K) on the behavior of cesium 137 (137Cs) in hydroponically cultured rice plants (Oryza sativa L. “Nipponbare”), revealing that K supply has an influence on reducing 137Cs translocation from leaves to ears as well as decreasing 137Cs uptake by roots. When K was omitted from the culture solution and 1...
Article
Full-text available
The mechanisms underlying magnesium (Mg) uptake by plant roots remain to be fully elucidated. In particular, there is little information about the effects of Mg deficiency on Mg uptake activity. A Mg uptake kinetic study is essential for better understanding the Mg uptake system. We performed a Mg uptake tracer experiment in rice plants using (28)...
Article
The pattern of real-time 137Cs uptake by plants was visualized using a macroscopic real-time radioisotope imaging system. We found that 137Cs was easily taken up by rice plants only when it was dissolved in a liquid medium. In contrast, only a small amount of 137Cs was taken up when the same liquid medium containing 137Cs was added to the soil and...
Article
We present a quantitative imaging of 28Mg in Arabidopsis using real‐time RI imaging system(RRIS). First, performance of RRIS in quantitative determination was characterized using standard spots. The results showed that the dynamic range for 28Mg determination was three orders of magnitude. Next, quantitative accuracy of measurement was studied for...
Article
Full-text available
Microautoradiography (MAR) is a conventional imaging method based on the daguerreotype. The technique is used to visualize the distribution of radionuclide-labeled compounds within a tissue section. However, application of the classical MAR method to plant tissue sections is associated with several difficulties. In this study, we report an MAR meth...
Article
In plant research, radioisotope imaging provides useful information about physiological activities in various tissues and elemental transport between plant organs. To expand the usage of imaging techniques, a new system was developed to visualize beta particles, x-rays and gamma-rays emitted from plant bodies. This real-time radioisotope imaging sy...
Article
After the accident of the Fukushima 1 Nuclear Power Plant in March 2011, radioactive cesium was released and paddy fields in a wide area including Fukushima Prefecture were contaminated. To estimate the levels of radioactive Cs accumulation in rice produced in Fukushima, it is crucial to obtain the actual data of Cs accumulation levels in rice plan...
Article
Full-text available
After the accident of the Fukushima 1 nuclear power plant in March 2011, radioactive cesium was released and paddy field in a wide area of Fukushima Prefecture was contaminated. To reduce radioactive Cs uptake by rice, it is important to understand factors that affect Cs uptake in rice. Here we describe our study in 2011 and 2012 to investigate Cs...
Article
We have developed a real-time radioisotope imaging system (RRIS) that can nondestructively trace 14C-labeled chemicals in plants. In an experiment, after feeding 14CO2 to a plant, the plant was fixed inside a box where lighting was regulated, and beta rays emitted from the 14C in the plant were intermittently imaged using the developed system. As a...
Article
Full-text available
Maintenance of an appropriate magnesium ion (Mg(2+)) concentration is essential for plant growth. In Arabidopsis thaliana, the CorA-MRS2-ALR-type proteins, named MRS2/MGT family proteins, are reportedly localized in various membranes and they function in Mg transport. However, knowledge of this family in other plant species is extremely limited. Fu...
Article
Full-text available
We characterized magnesium (Mg) uptake and transport along the primary root of six-day-old rice seedlings (Oryza sativa L. cv. Nipponbare) using 28Mg as a radioactive tracer. We used a multi-compartment transport box, which separated the root region every 1 cm in order to apply 28Mg to a particular root region. Then, the root region was defined as...
Article
Full-text available
抄録 福島第一原子力発電所事故に伴って降下した放射性物質により,農畜産物の放射能汚染が広がった。農産物の放射性セシウムによる汚染は,事故時には水田に移植されていなかったイネ(コメ)においても一部の水田で確認されたことから,その汚染メカニズムの解明が強く求められている。本研究では,2011年に500Bq・kg-1付近の玄米が収穫された水田において,収穫期のイネと,そのイネが生育した水田土壌における放射性物質の分布を調べた。その結果,穂の直下の桿で他と比較して高い放射能が検出された。葉については,新しいものほどイメージング・プレートで検出されるシグナルが強く,放射性セシウム濃度も高いことが示された。比較対象として,土壌の放射性セシウム濃度はほぼ同レベルであるにもかかわらず玄米の濃度が検出限界(1...
Article
Full-text available
Participation of the intervascular transport system within the rice stem during cadmium (Cd) partitioning was investigated by characterizing 109Cd behaviour in the shoot. In addition, 45Ca, 32P, and 35S partitioning patterns were analysed for comparison with that of 109Cd. Each tracer was applied to the seedling roots for 15min, and the shoots were...