Ammonia Assimilation in the Roots of Nitrate- and Ammonia-Grown Hordeum Vulgare (cv Golden Promise).
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Observations suggest that ammonia assimilation occurs solely via the glutamine synthetase/glutamate synthase pathway in both nitrate- and ammonia-grown barley roots.Abstract:
15N kinetic labeling studies were performed on seedlings of Hordeum vulgare L. var. Golden Promise growing under steady state conditions. Patterns of label incorporation in the pools of nitrogen compounds of roots fed [15N]ammonium were compared with computer-simulated labeling curves. The data were found to be quantitatively consistent with a three-compartment model in which ammonium is assimilated solely into the amide-N of glutamine. Labeling data from roots fed [15N]nitrate were also found to be at least qualitatively consistent with the assimilation of ammonia into glutamine. Methionine sulfoximine almost completely blocked the incorporation of 15N label into the amino acid pools of barley roots fed [15N]nitrate. These observations suggest that ammonia assimilation occurs solely via the glutamine synthetase/glutamate synthase pathway in both nitrate- and ammonia-grown barley roots.read more
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Journal ArticleDOI
The role of glutamate dehydrogenase in plant nitrogen metabolism.
TL;DR: In vivo nuclear magnetic resonance spectroscopy, in vitro gas chromatography-mass spectrometry, and automated (15)N/(13)C mass spectromaetry have been used to demonstrate that glutamate dehydrogenase is active in the oxidation of glutamate, but not in the reductive amination of 2-oxogiutarate.
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Effects of Nitrogen Deficiency on the Absorption of Nitrate and Ammonium by Barley Plants
R. B. Lee,Kathryn A. Rudge +1 more
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Ammonium Uptake by Rice Roots (I. Fluxes and Subcellular Distribution of 13NH4
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Feedback Regulation of Nitrate Influx in Barley Roots by Nitrate, Nitrite, and Ammonium
TL;DR: The short-lived radiotracer 13N was used to study feedback regulation of nitrate influx through the inducible high-affinity transport system of barley roots, finding that nitrate itself was capable of exercising feedback regulation upon its own influx.