Abstract
The metabolism of labelled pyruvate followed by 13C NMR and the measure of glutamine synthetase (GS) showed, according to previous results, a high activity of this enzyme in suspension cells of Nicotiana plumbaginifolia. This activity could derive glutamate from the alkaloid synthesizing pathways. However, a recent work showed that the rate of the GS gene transcription was inversely proportional to the Gln/Glu ratio. The measures of Gln and Glu concentrations in Nicotiana plumbaginifolia cells revealed that high GS activity correlates with the weak value of Gln/Glu ratio. Therefore, the hypothesis of GS dysfunctioning for the non-biosynthesis of alkaloids in N. plumbaginifolia suspension cells can be discarded. This conclusion is strengthened by the results obtained when using a GS inhibitor.
MeSH terms
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Alkaloids / biosynthesis*
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Cells, Cultured
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Datura stramonium / genetics
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Datura stramonium / metabolism*
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Enzyme Induction
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Enzyme Inhibitors / pharmacology
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Gene Expression Regulation, Plant
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Glutamate-Ammonia Ligase / antagonists & inhibitors
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Glutamate-Ammonia Ligase / genetics
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Glutamate-Ammonia Ligase / metabolism*
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Glutamic Acid / biosynthesis*
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Glutamine / biosynthesis*
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Magnetic Resonance Spectroscopy
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Methionine Sulfoximine / pharmacology
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Nicotiana / genetics
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Nicotiana / metabolism*
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Plant Proteins / antagonists & inhibitors
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Plant Proteins / genetics
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Plant Proteins / metabolism*
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Plants, Medicinal*
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Plants, Toxic*
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Species Specificity
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Suspensions
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gamma-Aminobutyric Acid / biosynthesis*
Substances
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Alkaloids
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Enzyme Inhibitors
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Plant Proteins
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Suspensions
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Glutamine
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Methionine Sulfoximine
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Glutamic Acid
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gamma-Aminobutyric Acid
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Glutamate-Ammonia Ligase