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  • Author or Editor: T. Nakanishi x
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Abstract  

We present an elemental profile pattern during the developmental stageof a soybean plant. By neutron activation analysis (NAA), we measured transitionelements, V, Cr, Mn, Fe and Zn. Vanadium and Fe were accumulated in a rootand Cr concentration in a plant was very low throughout the developmentalstage. The concentrations of Mn and Zn in leaves, especially in upper partof the plant, were higher than those in stems. Vanadium treatment inducedlow concentration of Fe in the root.

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Abstract  

We present Na, Mg, Al, K and Ca profiles, determined by neutron activationanalysis (NAA) in a soybean plant during its life cycle in water culture.The concentrations of Mg and Ca in leaves were higher than the other tissuesduring the developmental stage of a plant. The concentration of K was relativelyuniform within a plant. When a plant was treated with V, element uptake amount,especially Mg, K and Ca, was decreased throughout the life cycle. Vanadiumtreatment also induced low concentration of Mg and K in roots.

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In the study of aluminum toxicity for plant, it is important to analyzethe behavior of Al in cells. We present how Al is taken up by tobacco cellsthrough lumogallion staining method developed by our laboratory. The fluorescenceintensity from the cell was increased rapidly between 4 and 8 hours of 1 mMAl treatment. To calibrate the fluorescence intensity from Al-lumogallioncomplex, Al amount in the cell was determined by NAA. When the same samplewas analyzed by ICP-AES, Al amounts in all the samples were 13% lower thanthose measured by NAA.

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Abstract  

We discussed the relationship between Al toxicity and the Al, Fe andB amount of element in tobacco and grape cells. Al and Fe were analyzed byneutron activation analysis and B was analyzed by prompt gamma-ray analysis.Callose content was also measured as an indicator of cell damage induced Altoxicity. When tobacco cells were incubated in 1 mM and 300 µM Al solution,the pattern of callose formation was much similar to that of Fe accumulationthan that of Al accumulation in tobacco cells, suggesting that the increaseof Fe content induced toxic effect along with Al incorporated into the cells.However, this tendency was not observed in grape cells. Boron content didnot show any relation to those of Al or Fe throughout the Al treatment inboth tobacco and grape cells.

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Abstract  

Simple nitric acid leaching and alkali fusion techniques for the determination of the total content of fallout239,240Pu in deep-sea sediment were compared. Leaching neither with boiling conc. HNO3 nor with boiling conc. HNO3+H2O2 was found to be sufficient. The sodium hydroxide fusion technique yielded reproducible analytical results and is proposed as an optimum dissolution method for quantitative determination of the total content of fallout239,240Pu in deep-sea sediment.

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Abstract  

We present the kinetics of seven element profiles, macroscopic elements, Na, Mg, Cl, K and Ca, as well as Al and Br, in every tissue of morningglory (Ipomoea nil L. c.v. Murasaki), from seedling to flowering stage. Barriers for the elements were formed even in the same tissue during different growing phases. Most of Na and Al remained in root tissue, showing the first barrier to the upper part of the plant. During the juvenile phase, the tissues lower than cotyledon stored the elements, especially Ca and Mg. The barrier at cotyledon did not disappear completely until seed ripening stage, except for K. Generally, late developing stem showed lower accumulation of the elements, which seemed to regulate the inflow of Mg, Ca, Cl and Br into flowering tissue. The concentrations of K, Ca, Cl and Br in leaf were kept constant in spite of twice or three times higher concentration of these elements in leaf petiole. After flowering, selective element accumulation was observed during seed development, where most of the elements were accumulated into seed wall, not in seed. Higher concentration of the elements in elder leaf, which falls into ground and will be reused as plant nutrient, might reflect the recycling system of the elements in plants.

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Summary  

Though it has been reported that the accumulation of Cd in plant tissue increases with the decrease of the pH in soil, the mechanism of Cd accumulation in plant has not yet been clarified. Therefore, we investigated the effect of rhizosphere pH condition on the Cd accumulation in a soybean plant root, which is a gate for Cd uptake, using 109Cd tracer and an imaging plate (IP). Cadmium uptake by root tissue was found to be a fast reaction, since the amount of Cd uptake reached the plateau within about 2 hours (its time constant was about 20 minutes), Cd was easily transported into root apoplast, and moreover, its dynamics did not depend on an environmental pH condition (pH 4.5, 6.5). However, it was suggested that the amount of Cd taken up from the root was much higher in acidic conditions. Through image analysis taken by the IP, the accumulation and translocation of Cd were studied in roots.

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Summary  

Neutron radiography (NRG) was applied to trace the development of discolored tissue in the wood of Japanese cedar (Cryptomeria japonica) after being infected with a canker fungus. Japanese cedar seedlings were wound inoculated with a virulent and avirulent isolate of a canker fungus, Guignardia cryptomeriae. Three, 7, 13 and 22 days after the inoculation, the seedlings were irradiated with thermal neutrons. The image on the X-ray film showed that the whiteness in the image corresponded to the water content in the sample. Discolored tissue and surrounding dry zones induced by the fungal inoculation were detected as dark areas, indicating water deficiency with a high resolution. Through image analysis, the dry zones were detected as early as 3 days after inoculation. Neutron images also showed the difference in the size of water deficient parts due to the tissue damage among the treatments. The neutron beam dose used in this experiment had no effect on the growth rate of the fungus on a medium, showing that NRG is an effective method for pathological research of trees.

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Abstract  

Host phases of fallout239,240Pu and241Am were studied in the surface sediments obtained in 1994 from abyssal basins of relatively small area of the western North Pacific. An analytical procedure involving sequential chemical extraction was employed for partitioning the host phases of the nuclides in sediment into five fractions: (1) exchangeable (2) bound to carbonate, (3) bound to hydrous Fe-Mn oxides, (4) bound to organic matter and (5) residual. Decrease of total239,240Pu concentration with decreasing association of239,240Pu with organic matter, high241Am/239,240Pu activity ratio in carbonate phase and somewhat high proportion of oxidized239,240Pu in leachable phases suggest a possibility of post-depositional diagenetic remobilization of Pu from sediment to water column.

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Abstract  

Low-energy photon spectrometry (LEPS) with Si(Li) detector is used for the nondestructive analysis of elements in complex environmental materials.

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