鈴井 伸郎*; 柴田 卓弥; 尹 永根*; 船木 善仁*; 栗田 圭輔; 保科 宏行*; 山口 充孝*; 藤巻 秀*; 瀬古 典明*; 渡部 浩司*; et al.
Scientific Reports (Internet), 10, p.16155_1 - 16155_9, 2020/10
Visualizing the dynamics of cesium (Cs) is desirable to understand the impact of radiocesium when accidentally ingested or inhaled by humans. The positron-emitting nuclide Cs was produced using the I (, 4n) Cs reaction, which was induced by irradiation of sodium iodide with a He beam from a cyclotron. We excluded sodium ions by using a material that specifically adsorbs Cs as a purification column and successfully eluted Cs by flowing a solution of ammonium sulfate into the column. We injected the purified Cs tracer solution into living rats and the dynamics of Cs were visualized using positron emission tomography; the distributional images showed the same tendency as the results of previous studies using disruptive methods. Thus, this method is useful for the non-invasive investigation of radiocesium in a living animal.
鈴井 伸郎; 丸山 哲平*; 河地 有木; 三輪 睿太郎*; 樋口 恭子*; 藤巻 秀
JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 95, 2016/02
Common reed, which is classified to the same family as rice, is a salt-tolerant plant. In this study, we conducted non-invasive imaging of Na dynamics in intact common reed plants by using Na tracer and a positron-emitting tracer imaging system (PETIS) in order to understand the salt-tolerant mechanism in common reed. Common reeds and rice plants were cultivated in a nutrient solution containing 50 mM NaCl. After Na was fed into the solution, we observed the Na movement from the solution to the shoot for 24 h using PETIS. As a result, Na was strongly accumulated in the shoot base but not transported to the upper shoot in common reed, whereas Na was continuously transported to the upper shoot in rice plant. Furthermore, we replaced the original solution with a fresh nutrient solution without Na and traced the Na movement inside the plants for 18 h. Detailed quantitative analysis of the image data revealed that Na migrated downward from the shoot base to the root tip in common reed. These results indicate that common reed has constitutive ability of Na exclusion only in the direction of root tips, and consequently keeps low Na concentration in the upper shoot.
尹 永根; 河地 有木; 鈴井 伸郎; 石井 里美; 吉原 利一*; 渡部 浩司*; 山本 誠一*; 藤巻 秀
JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 112, 2016/02
Large areas of agricultural fields were contaminated with radiocesium (Cs and Cs) in Japan by the accident of The Tokyo Electric Power Company Fukushima Daiichi Nuclear Power Station in March 2011. Many agricultural studies, such as fertilizer management and plant breeding, are undertaken for reducing radiocesium uptake in crops or enhancing of uptake and transportation via phytoremediation. These studies examine the control of radiocesium transport into/within plant bodies from the viewpoint of plant physiology. Radiotracer imaging is one of the few methods that enable the observation of the movement of substances in a living plant, like a video camera, without sampling of the plant tissues. In this study, we performed the imaging of Cs uptake and transport from root to aerial part by using a new gamma camera in intact soybean plants because contamination of soybean by radiocesium has currently become a major problem in agriculture in Fukushima.
河地 有木; 尹 永根; 鈴井 伸郎; 石井 里美; 吉原 利一*; 渡部 浩司*; 山本 誠一*; 藤巻 秀
JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 94, 2016/02
We developed an original gamma camera system to image radiocesium in a plant. The gamma camera was designed for high-energy gamma photons from Cs radiocesium (662 keV). We performed tests to evaluate the position resolution and quantitative linearity of the gamma camera. The best spatial resolution of this gamma camera was determined to be 19.1 mm in full width at half maximum at the center of the field-of-view. And a result shows a quantitative linearity of the image data with a correlation of = 0.9985 between the source activity and the count rate. We conclude the gamma camera system has sufficiently high capability to obtain quantitative and dynamic images of Cs movement in intact plants.
石井 里美; 山崎 治明*; 鈴井 伸郎; 尹 永根; 河地 有木; 島田 浩章*; 藤巻 秀
JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 93, 2016/02
Tomato is popularly grown in environmentally controlled system such as a greenhouse for improvement of bioproduction. It is important to control the condition in the greenhouse for increasing the translocation of fixed carbon from the leaves to the growing fruits. Elevation of COconcentration is widely employed for that purpose; however, it is difficult to estimate its effect quantitatively because tomato plants have too large inter-individual variations with developing fruits. In this study, we employed a PETIS which is a live-imaging system of nutrients in plant body using short-lived radioisotopes including C. We also established a closed cultivation system to feed a test plant with CO at set concentrations of 400, 1,500 and 3,000 ppm and a pulse of CO.
放影協ニュース, (86), p.14 - 15, 2016/01
アメリカ合衆国カリフォルニア州サンディエゴのタウンアンドカントリーホテル国際会議場において、2015年10月31日から11月7日まで、米国電気電子学会(Institute of Electrical and Electronics Engineers: IEEE)の原子核プラズマ協会が主催した核科学国際会議(IEEE Nuclear Science Symposium)が開催された。著者は放射線影響協会の国際交流助成により、これに参加した。著者が発表した演題「Design and Performance of Newly Manufactured Pinhole Collimator of High-Resolution Gamma Camera for Imaging Radiocesium in a Plant Body」の内容を含め、2015年度の核科学国際会議の様子について報告する。
河地 有木; 尹 永根; 鈴井 伸郎; 石井 里美; 吉原 利一*; 渡部 浩司*; 山本 誠一*; 藤巻 秀
Journal of Environmental Radioactivity, 151(Part 2), p.461 - 467, 2016/01
We developed a new gamma camera specifically for plant nutritional research and successfully performed live imaging of the uptake and partitioning of Cs in intact plants. The gamma camera was specially designed for high-energy photons from Cs (662 keV). To obtain reliable images, a pinhole collimator made of tungsten heavy alloy was used to reduce penetration and scattering of photons. The array block of the GAGG scintillator was coupled to a high-quantum efficiency position sensitive photomultiplier tube to obtain accurate images. The completed gamma camera had a sensitivity of 0.83 count s MBq for Cs, and a spatial resolution of 23.5 mm. We used this gamma camera to study soybean plants that were hydroponically grown and fed with 2.0 MBq of Cs for 6 days to visualize and investigate the transport dynamics in aerial plant parts. Cs gradually appeared in the shoot several hours after feeding, and then accumulated preferentially and intensively in growing pods and seeds; very little accumulation was observed in mature leaves. Our results also suggested that this gamma-camera method may serve as a practical analyzing tool for breeding crops and improving cultivation techniques resulting in low accumulation of radiocesium into the consumable parts of plants.
放射線と産業, (138), p.48 - 51, 2015/06
アメリカ合衆国イリノイ州シカゴのハイヤットリージェンシー国際会議場において、2014年8月24日から28日まで、アイソトープの応用研究の発表とそれに関連した企業展示が行われる国際会議(8th International Conference on Isotopes and Expo: ICI8)がアメリカ原子力学会主催のもと開催された。国際会議ICI8全体の様子、さらに著者が口頭発表を行ったアイソトープによる農学・植物科学分野の研究発表セッション「Isotopes in Plant Biology: Future Sustainability in Energy and Agriculture」の様子について報告した。
吉原 利一*; 長尾 悠人; 橋田 慎之介*; 河地 有木; 藤巻 秀
電力中央研究所報告(O14002), 19 Pages, 2015/05
藤巻 秀; 丸山 哲平*; 鈴井 伸郎; 河地 有木; 三輪 睿太郎*; 樋口 恭子*
Plant & Cell Physiology, 56(5), p.943 - 950, 2015/05
山本 誠一*; 歳藤 利行*; 小森 雅孝*; 森下 祐樹*; 奥村 聡*; 山口 充孝; 齋藤 勇一; 河地 有木; 藤巻 秀
Annals of Nuclear Medicine, 29(3), p.268 - 275, 2015/04
In proton therapy, imaging of proton-induced positrons is a useful method to monitor the proton beam distribution after therapy. We developed a small field-of-view gamma camera for high-energy gamma photons and used it for monitoring the proton-induced positron distribution. The gamma camera used 0.85 mm 0.85 mm 10 mm GAGG pixels arranged in 20 20 matrix to form a scintillator block, which was optically coupled to a 1-inch-square position-sensitive photomultiplier tube. The GAGG detector was encased in a 20-mm-thick container and a pinhole collimator was mounted on its front. The gamma camera had spatial resolution of approximately 6.7 cm and sensitivity of 3.2 10 at 1.2 m from the collimator surface. The gamma camera was set 1 m from the 35 cm 35 cm 5 cm plastic phantom in the proton therapy treatment room, and proton beams were irradiated to the phantom with two proton energies. For both proton energies, positron distribution in the phantom could be imaged by the gamma camera with 10-min acquisition. The lengths of the range of protons measured from the images were almost identical to the calculation. These results indicate that the developed high-energy gamma camera is useful for imaging positron distributions in proton therapy.
山崎 治明*; 鈴井 伸郎; 尹 永根; 河地 有木; 石井 里美; 島田 浩章*; 藤巻 秀
Plant Biotechnology, 32(1), p.31 - 37, 2015/04
To maximize fruit yield of tomatoes cultivated in a controlled, closed system such as a greenhouse or a plant factory at a limited cost, it is important to raise the translocation rate of fixed carbon to fruits by tuning the cultivation conditions. Elevation of atmospheric CO concentration is a good candidate. In this study, we employed a positron-emitting tracer imaging system (PETIS), which is a live-imaging technology for plant studies, and a short-lived radioisotope C to quantitatively analyze immediate responses of carbon fixation and translocation in tomatoes in elevated CO conditions. We also developed a closed cultivation system to feed a test plant with CO at concentrations of 400, 1500 and 3000 ppm and a pulse of CO. As a result, we obtained serial images of C fixation by leaves and subsequent translocation into fruits. Carbon fixation was enhanced steadily by increasing the CO concentration, but the amount translocated into fruits saturated at 1500 ppm on average. The translocation rate had larger inter-individual variation and showed less consistent responses to external CO conditions compared with carbon fixation.
鈴井 伸郎; 河地 有木; 石井 里美; 尹 永根; 岩崎 郁*; 小川 健一*; 藤巻 秀
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 105, 2015/03
In this study, we developed an analytical method to evaluate velocity of photoassimilate flow using C-tracer and the positron-emitting tracer imaging system (PETIS). CO gas tracer was fed to the compound leaves of the soybean plant, and serial images of C distribution were obtained by PETIS. Regions of interests (ROIs) were set in the node of the first compound leaf (ROI-1) and the stem base (ROI-2). Time course of C-radioactivity (Time-Activity Curve: TAC) in each ROI was generated from the serial images. Initial slope of the rising C-radioactivity was estimated by a linear least-square method using the TAC data. The value of the intercept of approximated line to the background line (X-intercept) was defined as "C-arrival time" to the ROIs. In order to determine X-intercept with a fair criterion, we developed an analytical program. The velocities of C-photoassimilate flows of 18 individual soybean plants were estimated by the values of C-arrival time and the distance between ROI-1 and ROI-2. As a result, the average value of the velocity was 113 cm h and the standard deviation was 20 cm h. This result indicates the newly developed method is a reliable tool for the quantitative analysis of photoassimilate flow through the phloem.
核医学物理学, p.280 - 284, 2015/03
山本 誠一*; 緒方 良至*; 河地 有木; 鈴井 伸郎; 尹 永根; 藤巻 秀
Nuclear Instruments and Methods in Physics Research A, 777, p.102 - 109, 2015/03
After the nuclear disaster in Fukushima, radiocesium contamination became a serious scientific concern and research of its effects on plants increased. In such plant studies, high resolution images of radiocesium are required without contacting the subjects. Cherenkov light imaging of beta radionuclides has inherently high resolution and is promising for plant research. Since Cs and Cs emit beta particles, Cherenkov light imaging will be useful for the imaging of radiocesium distribution. Consequently, we developed and tested a Cherenkov light imaging system. We used a high sensitivity cooled charge coupled device (CCD) camera for imaging Cherenkov light from Cs and Cs. A bright lens was mounted on the camera and placed in a black box. With a 100-m Cs point source, we obtained 220-m spatial resolution in the Cherenkov light image. With a 1-mm diameter, 320-kBq Cs point source, the source was distinguished within 2-s. We successfully obtained Cherenkov light images of a plant whose root was dipped in a Cs solution, radiocesium-containing samples as well as line and character phantom images with our imaging system. Cherenkov light imaging is promising for the high resolution imaging of radiocesium distribution without contacting the subject.
放影協ニュース, (82), p.4 - 6, 2015/01
スペイン国カタルーニャ州の州都バルセロナの国際会議場において、2014年9月7日から12日まで、放射生態学と環境放射能に関する国際会議(3rd International Conference on Radioecology and Environmental Radioactivity: ICRER 2014)が開催された。著者は放射線影響協会の国際交流助成により、これに参加した。国際会議ICRER2014の様子、さらに著者が行った口頭発表について報告した。
中村 進一*; 近藤 ひかり*; 鈴井 伸郎; 尹 永根; 石井 里美; 河地 有木; 頼 泰樹*; 服部 浩之*; 藤巻 秀
Molecular Physiology and Ecophysiology of Sulfur, p.253 - 259, 2015/00
Glutathione is a sulfur-containing peptide involved in various aspects of plant metabolism. Glutathione is also known to have effects on heavy metal responses in plants. In our previous work, we have found glutathione, applied to roots site- specifically, inhibited cadmium (Cd) translocation from roots to shoots and Cd accumulation in shoots in oilseed rape plants. In addition, we succeeded in visualizing inhibition of root-to-shoot translocation of Cd by using a positron-emitting tracer imaging system (PETIS). In this work, the effects of glutathione concentration in the root zone (hydroponic solution) and the glutathione treatment period on Cd partitioning in oilseed rape plants were investigated. Our experimental results demonstrated that glutathione, exceeding a certain concentration in the root zone, is needed to trigger inhibition of Cd translocation, and that treatment time from the start of glutathione application had different effects on Cd partitioning in oilseed rape plants.
高橋 竜一*; 石丸 泰寛*; Shimo, H.*; Bashir, K.*; 瀬野浦 武志*; 杉本 和彦*; 小野 和子*; 鈴井 伸郎; 河地 有木; 石井 里美; et al.
PLOS ONE (Internet), 9(6), p.e98816_1 - e98816_7, 2014/06
Previously, we reported that OsNRAMP5 functions as a manganese, iron, and cadmium (Cd) transporter. The shoot Cd content in RNAi plants was higher than that in wild-type (WT) plants, whereas the total Cd content (roots plus shoots) was lower. For efficient Cd phytoremediation, we produced RNAi plants using the natural high Cd-accumulating cultivar Anjana Dhan (A5i). Using a positron-emitting tracer imaging system, we assessed the time-course of Cd absorption and accumulation in A5i plants. Enhanced Cd translocation from the roots to the shoots was observed in A5i plants. To evaluate the phytoremediation capability of A5i plants, we performed a field experiment in a Cd-contaminated paddy field. The biomass of the A5i plants was unchanged by the suppression of expression; the A5i plants accumulated twice as much Cd in their shoots as WT plants. Thus, A5i plants could be used for rapid Cd extraction and the efficient phytoremediation of Cd from paddy fields, leading to safer food production.
吉原 利一*; 鈴井 伸郎; 石井 里美; 北崎 真由*; 山崎 治明*; 北崎 一義*; 河地 有木; 尹 永根; 七夕 小百合*; 橋田 慎之介*; et al.
Plant, Cell & Environment, 37(5), p.1086 - 1096, 2014/05
Cadmium (Cd) accumulations in a Cd hyper-accumulator fern, (), and tobacco, (), were kinetically analysed using the positron-emitting tracer imaging system under two medium conditions (basal and no-nutrient). In , maximumly 50% and 15% of the total Cd accumulated in the distal roots and the shoots under the basal condition, respectively. Interestingly, a portion of the Cd in the distal roots returned to the medium. In comparison with , a little fewer Cd accumulations in the distal roots and clearly higher Cd migration to the shoots were observed in under the basal condition (maximumly 40% and 70% of the total Cd, respectively). The no-nutrient condition down-regulated the Cd migration in both species, although the regulation was highly stricter in than in (almost no migration in and around 20% migration in ). In addition, the present work enabled to estimate physical and physiological Cd accumulation capacities in the distal roots, and demonstrated condition-dependent changes especially in . These results clearly suggested occurrences of species-/condition-specific regulations in each observed parts. It is probable that integration of these properties govern the specific Cd tolerance/accumulation in and .
山本 誠一*; 渡部 浩司*; 河地 有木; 藤巻 秀; 加藤 克彦*; 畑澤 順*
Nuclear Instruments and Methods in Physics Research A, 743, p.124 - 129, 2014/04
Using Ce-doped GSO of different Ce concentrations, three-layer depth-of-interaction (DOI) block detectors were developed to reduce the parallax error at the edges of a pinhole gamma camera for high-energy photons. GSOs with Ce concentrations of 1.5 mol%, 0.5 mol% crystal, 0.4 mol% were selected for the DOI detectors. These three types of GSOs were optically coupled in the depth direction, arranged in a 22 22 matrix and coupled to a flat panel photomultiplier tube. With these combinations of GSOs, all spots corresponding to GSO cells were clearly resolved in the position histogram. Pulse shape spectra showed three peaks for these three decay times of GSOs. The block detector was contained in a tungsten shield, and a pinhole collimator was mounted. With pulse shape discrimination, we separated the point source images of the Cs-137 for each DOI layer. The point source image of the lower layer was detected at the most central part of the field-of-view (FOV), and the distribution was the smallest. The point source image of the higher layer was detected at the most peripheral part of the FOV, and the distribution was widest. With this information, the spatial resolution of the pinhole gamma camera can be improved. We conclude that DOI detection is effective for pinhole gamma cameras for high energy photons.