Kunio Oohashi

Transport of Trace Elements through the Hyphae of an Arbuscular Mycorrhizal Fungus into Marigold Determined by the Multitracer Technique

Abstract The contribution of the hyphae of an arbuscular mycorrhizal (AM) fungus to the uptake of traceelements by marigold (Tagetes patula L.) was studied using a multitracer consisting of radionuclides of 7Be, 22Na, 46Sc, 51Cr, 54Mn, 59Fe, 56Co, 65Zn, 75Se, 83Rb, 85Sr, 88Y, 88Zr, and 95mTc. Marigold plants colonized and not colonized with Glomus etunicatum were grown for 40 and 60 d in pots with a hyphal compartment separated from the rooting medium by a fine nylon mesh. The multitracer was applied to the hyphal compartment. We found that the uptake of 22Na, 65Zn , 75Se, 83Rb, 85Sr, and 88Y by the mycorrhizal plants was higher than that by the non-mycorrhizal ones. In the case of 95mTc, the uptake by the mycorrhizal plants was similar to that by the control ones. The radioactivity of 7Be, 46Sc, 51Cr, 54Mn, 59Fe, 56Co, and 88Zr could not be detected in any plants. Our results suggest that the AM fungus can absorb Na, Zn, Se, Rh, Sr, and Y from the soil and transport these elements to the plant through its hyphae. The transport ability of the AM fungal hyphae to plant for Be, Sc, Cr, Mn, Fe, Co, Zr, and Tc is likely to be low.

Uptake of 15 trace elements in arbuscular mycorrhizal marigold: Measured by the multitracer technique

Abstract The effect of arbuscular mycorrhizal (AM) colonization on the uptake of trace elements in marigold (Tagetes patula L.) was studied using a multitracer consisting of radionuclides of 7Be, 22Na, 46Sc, 51Cr, 54Mn, 59Fe, 56Co, 65Zn, 74As, 75Se, 83Rb, 85Sr, 88Y, 88Zr, and 95mTc. Marigold plants were grown under controlled environmental conditions in sand culture either without mycorrhizas or in association with an AM fungus, Glomus etunicatum. The multitracer was applied to the pot, and plants were harvested at 7 and 21 d after tracer application. We found that the uptake of 7Be, 22Na, 51Cr, 59Fe, 65Zn, and 95mTc was higher in the mycorrhizal marigolds than in the non-mycorrhizal ones, while that of 46Sc, 56Co, 83Rb, and 85Sr was lower in the mycorrhizal marigolds than in the non-mycorrhizal ones. Thus, the multitracer technique enabled to analyze the uptake of various elements by plant simultaneously. It is suggested that this technique could be used to analyze the effects of AM colonization on the uptake of trace elements by plant.

RhCl3·3H2O catalyzed tritiation of acid amides with HTO

It was established by chemical degradation that RhCl3·3H2O catalyzed tritiation with HTO occurred with virtually 100% regioselectivity at the ortho-positions of benzamide as well as various anilides and benzoic acid. While tritiation has not been found in the alkyl C−H bond in anilide molecules, in the present experiments tritium was incorporated into the active methylene group of α-phenylacetamide. This finding suggests that the present tritiation occurs more readily at polar Cδ-−Hδ+ bonds than at nonpolar ones in accordance with previous results.

Radioselective tritiation of acetailide and para-substituted acetanilides

Acetanilide and para-substituted acetanilides were tritiated by heating with HTO in the presence of RhCl3.3H2O as a catalyst in an N,N-dimethylformamide solution at 105–107°C for 18 h. Under such conditions, tritium introduced into the anilide molecules was found at the adjacent ortho positions to the acetamido group with virtually 100% regioselectivity. The substituent effect on the rate of tritiation was observed.

Synthesis of186Re-DMSA and its biodistributions in mice

Optimum conditions were determined for high-yield synthesis of186Re- and188Re-meso-2, 3-dimercaptosuccinic acid complexes applicable to animal injection. The yield was more than 95% under the conditions used. The bone accumulation of the complexes was remarkable in the biodistributions in mice.

Tritiation of toluene with HTO

Toluene was tritiated singly or as an equimolar mixture with benzene using HTO in the presence of FeCl3 as a catalyst. An o, poriented tritium distribution in the ring of toluene at the initial stage of reaction changed into uniform one with elapse of reaction time at 40 °C, whereas such a rapid change was not observed at 5 °C. By tritiation of the equimolar mixture at 6 °C, the partial rate factors were determined as of=264, mf=7, and pf=189 at the initial stage of the reaction. A possible reaction mechanism is discussed.

Regioselective tritiation of benzoic acid and its alkali metal salts. The action of benzoate ions

Benzoic acid, lithium benzoate, and sodium benzoate were tritiated with virtually 100% regioselectivity in the ortho-positions by the T-for-H exchange reaction with HTO in the presence of RhCl3.3H2O. The labeling of both alkali metal salts was favored by a factor of about 3 over that of benzoic acid. Methyl benzoate was essentially inactive in the present reaction.

Reactions of recoil tritium generated by the3He/n,p/3H reaction with aromatic compounds-intramolecular tritium distribution and radiochemical yield

Reactions of recoil tritium with benzoic acid, acetanilide and β-phenethyl alcohol were studied using the3He/n,p/3H reaction. The tritium distribution in the aromatic ring is approximately uniform in all the irradiated compounds and the tritium activity per C−H bond in the methyl and ethylene groups is 7 to 8 relative to that of the corresponding ring as standard /=100/. These findings are substantially the same as those obtained previously by the6Li/n,α/3H reactions, suggesting the same mechanism of tritiation for both recoil reactions. The tritiated parent compounds were obtained in high radiochemical yields; 45% for benzoic acid, 30% for acetanilide, 12% for β-phenethyl alcohol.

Tritation of benzoic acid by 6Li(n,α)3H reaction with enriched lithium‐6

Lithium benzoate containing 95 atom% lithium-6 (abbreviation: enriched) was tritiated by neutron irradiation in a pile. The degree of tritium incorporation to the benzene ring was 6.9 to 7.6 times that for the benzoate of natural isotopic abundance (abbreviation: natural abundance) according to the sample size, i.e., the geometries of irradiation samples were compared under the same thermal neutron fluence. The computed self-shielding effect for incident neutrons was negligible in the irradiation of the latter benzoate, while in the case of the former one rather large effects were observed in thick samples used in the present experiment. The tritium distribution in the benzene ring showed a slight ortho orientation in the irradiation of enriched 6Li compound, but was almost uniform in the other compounds. Copyright

Steric Effect of Methyl Group in Regioselective Tritiation of Toluamides.

Tritiation by the hydrogen isotope exchange in toluamides with HTO was studied in the presence of RhCl3⋅3H2O as a catalyst. It was established by chemical degradation that the exchange reaction occurred with virtually 100% regioselectivity at the o-position (s) (C2 and C6 positions) of all the toluamides. The methyl group was not tritiated. The exchange in m-toluamide was very strongly hindered at the C2 position between the methyl and the amido group. The exchange at the C6 position was more strongly prevented in o-toluamide than in m-toluamide. These findings are explained on the basis of the steric effect of the methyl group in agreement with the previously suggested mechanism that the exchange proceeds via initial coordination of the substrate compound to rhodium (III) chloride trihydrate.