Albrecht Roscher

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The aim of this work was to establish the influence of fructose 2,6-bisphosphate (Fru-2,6-P2) on non-photosynthetic carbohydrate metabolism in plants. Heterotrophic callus lines exhibiting elevated levels of Fru-2,6-P2 were generated from transgenic tobacco (Nicotiana tabacum L.) plants expressing a modified rat liver(More)
In higher plants the glutamate dehydrogenase (GDH) enzyme catalyzes the reversible amination of 2-oxoglutarate to form glutamate, using ammonium as a substrate. For a better understanding of the physiological function of GDH either in ammonium assimilation or in the supply of 2-oxoglutarate, we used transgenic tobacco (Nicotiana tabacum L.) plants(More)
Metabolic flux analysis, using 13C labeled substrates, has become a powerful methodology for quantifying intracellular fluxes. Most often, analysis is restricted to nuclear magnetic resonance or mass spectrometry measurement of 13C label incorporation into protein amino acids. However, amino acid isotopomer distribution insufficiently covers the entire(More)
The reaction of N-demethylation plays an important role in the degradation of some alkaloids in a number of organisms. This review presents how our understanding of the N-demethylation of nicotine in plants has been improved through studies in cell cultures of Nicotiana plumbaginifolia and N. glutinosa using a variety of isotopic techniques. The overall aim(More)
The dynamics of developing linseed embryo metabolism was investigated using (13)C-labelling experiments where the real-time kinetics of label incorporation into metabolites was monitored in situ using in vivo NMR. The approach took advantage of the occurrence in this plant tissue of large metabolite pools - such as sucrose or lipids - to provide direct and(More)
The conversion of nicotine to nornicotine by Nicotiana plumbaginifolia Viv. cells was investigated by analysing the redistribution of label during feeding experiments with (R,S)-[2H-methyl]nicotine, (R,S)-[13C-methyl]nicotine and (R,S)-[14C-methyl]nicotine, and the results show that the N-methyl group of nicotine can be recycled into primary metabolism.(More)
We describe an approach to extract (13)C-labeled sugars (glucose, fructose, maltose, sucrose, myo-inositol as well as glucose from starch) from plant tissues and to analyze their isotopomer distribution by gas chromatography-mass spectrometry (GC-MS). Sugars are derivatized with N,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA) into their Si(CH3)3(More)
Flaxseed is an important source of lignans and ω-3 fatty acids, compounds which present interest in human health with many applications in food industry. It is therefore necessary to precisely know the metabolite content in flaxseed. A metabolomic approach using NMR was developed to achieve this goal. Due to particular characteristics of flaxseed (high(More)
The use of in vivo NMR within the framework of Metabolic Flux Analysis in plants is presented. In vivo NMR allows to visualize the active metabolic network, to determine metabolic and isotopic steady state and to measure metabolic fluxes which are not necessarily accessible by isotopic steady state (stationary) Metabolic Flux Analysis. The kinetic data can(More)
Flax (Linum usitatissimum L.) seeds are widely used for oil extraction and the cold-pressed flaxseed (or linseed) cakes obtained during this process constitute a valuable by-product. The flavonol herbacetin diglucoside (HDG) has been previously reported as a constituent of the flaxseed lignan macromolecule linked through ester bonds to the linker molecule(More)