-
[show abstract]
[hide abstract]
ABSTRACT: The positron emitting tracer imaging system (PETIS) and carbon-11-labeled carbon dioxide (<sup>11</sup>CO<sub>2</sub>) can image carbon movement during photosynthesis in a plant leaf, and <sup>11</sup>C kinetics make it possible to estimate physiological function parameters in those photosynthesis processes. With an exposure <sup>11</sup>CO<sub>2</sub> gas to a leaf, PETIS experiments were performed iteratively under dark and light environments on a single leaf. In order to estimate the rate constants of photosynthetic parameters, time activity curves of <sup>11</sup>CO<sub>2</sub> gas input and leaf response were fitted to an appropriate compartmental tracer kinetic model, which applies influx and efflux for photo-assimilation and sucrose export rate constants respectively. Results obtained from the kinetic analysis are consistent with physiological knowledge and important to discuss photosynthesis in plant physiology and agriculture. In addition, the proposed method in this paper produce parametric images of photosynthetic functions on a pixel-by-pixel basis successfully, in other words, molecular imaging for plant study is demonstrated.
Nuclear Science Symposium Conference Record, 2006. IEEE; 12/2006
-
[show abstract]
[hide abstract]
ABSTRACT: The positron emitting tracer imaging system (PETIS) and carbon-11-labeled carbon dioxide (<sup>11</sup>CO<sub>2</sub>) can be used for imaging the photosynthesis process in plant leaves. Further, <sup>11</sup>C kinetics facilitate the estimation of the physiological function parameters of photosynthesis. PETIS measurements were performed under four light conditions for each exposure of a single leaf to <sup>11</sup>CO<sub>2</sub> gas. In order to estimate the rate constants of the photosynthesis parameters, the time-activity curves of the input <sup>11</sup>CO<sub>2</sub> gas and the leaf response were fitted to an appropriate compartmental tracer kinetic model that considers photoassimilation and sucrose export rate constants as influx and efflux, respectively. The data obtained by this method show a reasonable response with respect to the photoenvironment of the leaf, and they are important for discussing photosynthesis with regard to plant physiology and agriculture
IEEE Transactions on Nuclear Science 11/2006; · 1.45 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A radioisotope-production facility at the Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) of the Japan Atomic Energy Agency (JAEA) allows us to produce radioisotopes using accelerated beam from an AVF cyclotron. The facility has been constructed for research and development of potentially useful radioisotopes in medical research and physiological studies of plants. Experiments in these fields require a variety of radioisotopes and their labeled compounds during a limited machine time. Laboratory equipment has been designed and installed to treat high-level radioactivity and to irradiate a variety of targets (solid, liquid, gas....). The irradiation apparatus consists of two solid target chambers and a compact revolver equipped with six target chambers for gas and liquid targets, set on the movable table. It is possible to exchange rapidly and remotely the target chambers. The solid-target transfer system realized to carry automatically the irradiated target from irradiation position to the shielded-cell by a truck. Use of this facility enables us to produce routinely positron-emitting tracers for plant physiology and to develop the production method of carrier-free radioisotopes for medical use.
Nuclear Science Symposium Conference Record, 2005 IEEE; 11/2005
-
[show abstract]
[hide abstract]
ABSTRACT: Position emitting tracer imaging system (PETIS) and carbon-11-labeled carbon dioxide (<sup>11</sup>CO<sub>2</sub>) can image photosynthesis process in plant leaf, and <sup>11</sup>C kinetics make it possible to estimate physiological function parameters in photosynthesis. With an exposure <sup>11</sup>CO<sub>2</sub>-gas to a leaf, PETIS experiments were performed under four light conditions on a single leaf. In order to estimate the rate constants of photosynthesis parameters, time activity curves of <sup>11</sup>CO<sub>2</sub> gas input and leaf response were fitted to an appropriate compartmental tracer kinetic model, which applies influx and efflux for photo-assimilation and photosynthate delivery rate constants respectively. These results are reasonable response against light environment and important to discuss photosynthesis in plant physiology and agriculture.
Nuclear Science Symposium Conference Record, 2005 IEEE; 11/2005
-
[show abstract]
[hide abstract]
ABSTRACT: Quantitative analysis of the two-dimensional image data obtained with the positron-emitting tracer imaging system (PETIS) for plant physiology has been carried out using a transfer function analysis method. While a cut leaf base of Chinese chive (Allium tuberosum Rottler) or a cut stem of soybean (Glycine max L.) was immersed in an aqueous solution containing the [18F] F- ion or [13N]NO3- ion, tracer images of the leaf of Chinese chive and the trifoliate of soybean were recorded with PETIS. From the time sequence of images, the tracer transfer function was estimated from which the speed of tracer transport and the fraction moved between specified image positions were deduced.
Applied Radiation and Isotopes 09/2002; 57(2):225-33. · 1.17 Impact Factor
-
S. Kiyomiya,
H. Nakanishi,
H. Uchida,
S. Nishiyama,
H. Tsukada,
N. S. Ishioka,
S. Watanabe,
A. Osa,
C. Mizuniwa,
T. Ito, S. Matsuhashi,
S. Hashimoto,
T. Sekine,
A. Tsuji,
S. Mori
[show abstract]
[hide abstract]
ABSTRACT: Water (H2 15O) translocation from the roots to the top of rice plants (Oryza saliva L. cv. Nipponbare) was visualized over time by a positron-emitting tracer imaging system (PETIS). H2 15O flow was activated 8 min after plants were exposed to bright light (1 500 &mgr;mol m-2 s-1). When the light was subsequently removed, the flow gradually slowed and completely stopped after 12 min. In plants exposed to low light (500 &mgr;mol m-2 s-1), H2 15O flow was activated more slowly, and a higher translocation rate of H2 15O was observed in the same low light at the end of the next dark period. NaCl (80 mM) and methylmercury (1 mM) directly suppressed absorption of H2 15O by the roots, while methionine sulfoximine (1 mM), abscisic acid (10 &mgr;M) and carbonyl cyanide m-chlorophenylhydrazone (10 mM) were transported to the leaves and enhanced stomatal closure, reducing H2 15O translocation.
Physiologia Plantarum 12/2001; 113(3):359-367. · 3.11 Impact Factor
-
N Bughio,
H Nakanishi,
S Kiyomiya, S Matsuhashi,
N S Ishioka,
S Watanabe,
H Uchida,
A Tsuji,
A Osa,
T Kume,
S Hashimoto,
T Sekine,
S Mori
[show abstract]
[hide abstract]
ABSTRACT: [11C]Methionine was supplied through barley roots and the 11C signal was followed for 90 min using a real-time imaging system (PETIS), with subsequent development of autoradiographic images of the whole plant. In all cases, [11C]methionine was first translocated to the 'discrimination center', the basal part of the shoot, and this part was most strongly labeled. Methionine absorbed by the roots of the plants was subsequently translocated to other parts of the plant. In Fe-deficient barley plants, a drastic reduction in [11C]methionine translocation from the roots to the shoot was observed, while a greater amount of 11C was found in the leaves of Fe-sufficient or methionine-pretreated Fe-deficient plants. Treatment of Fe-deficient plants with aminooxyacetic acid, an inhibitor of nicotianamine aminotransferase, increased the translocation of [11C]methionine to the shoot. The retention of exogenously supplied [11C]methionine in the roots of Fe-deficient barley indicates that the methionine is used in the biosynthesis of mugineic acid phytosiderophores in barley roots. This and the absence of methionine movement from shoots to the roots suggest that the mugineic acid precursor methionine originates in the roots of plants.
Planta 10/2001; 213(5):708-15. · 3.00 Impact Factor
-
S Kiyomiya,
H Nakanishi,
H Uchida,
A Tsuji,
S Nishiyama,
M Futatsubashi,
H Tsukada,
N S Ishioka,
S Watanabe,
T Ito,
C Mizuniwa,
A Osa, S Matsuhashi,
S Hashimoto,
T Sekine,
S Mori
[show abstract]
[hide abstract]
ABSTRACT: The ammonium ion is an indispensable nitrogen source for crops, especially paddy rice (Oryza sativa L. cv Nipponbare). Until now, it has been impossible to measure ammonium uptake and nitrogen movement in plants in real time. Using the new technologies of PETIS (positron emitting tracer imaging system) and PMPS (positron multi-probe system), we were able to visualize the real time translocation of nitrogen and water in rice plants. We used positron-emitting 13N-labeled ammonium (13NH4+) and 15O-water to monitor the movement. In plants cultured under normal conditions, 13NH4+ supplied to roots was taken up, and a 13N signal was detected at the discrimination center, the basal part of the shoots, within 2 minutes. This rapid translocation of (13)N was almost completely inhibited by a glutamine synthetase inhibitor, methionine sulfoximine. In general, nitrogen deficiency enhanced 13N translocation to the discrimination center. In the dark, 13N translocation to the discrimination center was suppressed to 40% of control levels, whereas 15O-water flow from the root to the discrimination center stopped completely in the dark. In abscisic acid-treated rice, 13N translocation to the discrimination center was doubled, whereas translocation to leaves decreased to 40% of control levels. Pretreatment with NO3- for 36 hours increased 13N translocation from the roots to the discrimination center to 5 times of control levels. These results suggest that ammonium assimilation (from the roots to the discrimination center) depends passively on water flow, but actively on NH4+-transporter(s) or glutamine synthetase(s).
Plant physiology 05/2001; 125(4):1743-53. · 6.53 Impact Factor
-
N Ohtake,
T Sato,
H Fujikake,
K Sueyoshi,
T Ohyama,
N S Ishioka,
S Watanabe,
A Osa,
T Sekine, S Matsuhashi,
T Ito,
C Mizuniwa,
T Kume,
S Hashimoto,
H Uchida,
A Tsuji
[show abstract]
[hide abstract]
ABSTRACT: Non-nodulated soybean (Glycine max (L.) Merr.) plants were cultivated hydroponically under N-sufficient (5 mM NaNO(3)) or N-deficient (0.5 mM NaNO(3)) conditions. (13)N- or (15)N- labelled nitrate was fed to the cut end of the stems, and the accumulation of nitrate-derived N in the pods, nodes and stems was compared. Real-time images of (13)N distribution in stems, petioles and pods were obtained using a Positron Emitting Tracer Imaging System for a period of 40 min. The results indicated that the radioactivity in the pods of N-deficient plants was about 10 times higher than that of N-sufficient plants, although radioactivity in the stems and nodes of N-deficient versus N-sufficient plants was not different. A similar result was obtained by supplying (15)NO(3) to cut soybean shoots for 1 h. The fact that the N translocation into the pods from NO(3) fed to the stem base was much faster in N-deficient plants may be due to the strong sink activity of the pods in N-deficient plants. Alternatively, the redistribution of N from the leaves to the pods via the phloem may be accelerated in N-deficient plants. The temporal accumulation of (13)NO(3) in nodes was suggested in both N-sufficient and N-deficient plants. In one (13)NO(3) pulse-chase experiment, radioactivity in the stem declined rapidly after transferring the shoot from the (13)NO(3) solution to non-labelled NO(3); in contrast, the radioactivity in the node declined minimally during the same time period.
Journal of Experimental Botany 03/2001; 52(355):277-83. · 5.36 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A simple and reliable method for the determination of NH4+, K+, Na+, aspartic acid, asparagine, glutamine, and alanine by ion chromatography has been developed. It is suitable for monitoring changes of nitrogen metabolism in soybean because it can accurately measure concentrations o asparagine and NH4+, two key substances for nitrogen storage and transport in this plant species Analysis of asparagine distribution in soybean indicated that higher levels (up to 18.4 micromol g(-1) of fresh mass) occur in stems and lower levels in roots (2.0 micromol g(-1) of fresh mass) and leaves (1.6 micromol g(-1) of fresh mass). When the herbicide metsulfuron-methyl (0.5, 5, and 50 ppb) was applied via the nutrient solution to the root system, asparagine concentrations increased 3-6 times in stems roots, and leaves. Metsulfuron-methyl is known to impair the synthesis of branched amino acids and, in consequence, protein synthesis. Thus, nitrogen consumption was limited, leading to ar accumulation of asparagine. The possible use of this physiological response in agricultural practice to identify herbicide stress in soybean and to detect low-level residues of sulfonylurea herbicides ir the soil is discussed.
Journal of Agricultural and Food Chemistry 02/2001; 49(1):276-80. · 2.82 Impact Factor
-
N. S. Ishioka,
H. Matsuoka,
S. Watanabe,
A. Osa,
M. Koizumi,
T. Kume, S. Matsuhashi,
T. Fujimura,
A. Tsuji,
H. Uchida,
T. Sekine
[show abstract]
[hide abstract]
ABSTRACT: The positron emitters11C,13N and18F and their labeled compounds have been produced for studies on plants using a newly developed positron emitting tracer imaging
system. Although this system covers, at present, a limited area in a plant, the distribution of the positron emitter fed into
the plant can be visualized dynamically. Further development of positron-emitter-labeled compounds is expected to elucidate
the physiological function of plants in vivo.
Journal of Radioanalytical and Nuclear Chemistry 01/1999; 239(2):417-421. · 1.52 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Quantitative analysis of the two-dimensional image data obtained with the positron-emitting tracer imaging system (PETIS) for plant physiology has been carried out using a transfer function analysis method. While a cut leaf base of Chinese chive (Allium tuberosum Rottler) or a cut stem of soybean (Glycine max L.) was immersed in an aqueous solution containing the [18F] Fâ ion or [13N]NO3â ion, tracer images of the leaf of Chinese chive and the trifoliate of soybean were recorded with PETIS. From the time sequence of images, the tracer transfer function was estimated from which the speed of tracer transport and the fraction moved between specified image positions were deduced.
Applied Radiation and Isotopes.
-
-
J Yamaguchi,
Y Sonoda,
A Iwata,
A Ikeda,
T. Tsutsui,
C. Morita-Yamamuro,
S.-G. Yao, S. Matsuhashi,
S. Fujimaki,
K Sakamoto,
K Arakawa,
T Kume
