Regulation of Glutamate Dehydrogenase and Nitrate Reductase Levels in Excised Pea Roots by Exogeneously Supplied Sugar

Sahulka, J.; Gaudinová, Alena; Hadačová, Věra

doi:10.1016/s0044-328x(75)80133-4

Cited by 31 publications

(8 citation statements)

References 22 publications

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“…Sahulka, who also uses ecised roots and relatively short incubation periods, finds that the response of GDH, NR, and GS to NH~ § is not always apparent and is dependent on the accompanying anion (Sahulka, 1977;Sahulka and Lisa, 1979). In both his results (Sahulka et al, 1975 ;Sahulka and Lisa, 1978) and ours (Stulen and Oaks, 1977, and Table 2), sugars appear to play a more central role in the regulation of GDH, GS, AS, and GOGAT than do specific nitrogen sources.…”

Section: Discussionmentioning

confidence: 66%

“…Thus, although regulation is superficially similar, as indicated, for example, by the glucose effects on NR and GDH reported for corn roots and by Sahulka et al (1975) for pea roots, it is probably not yet correct to generalize on developmental sequences between plant species.…”

Section: Discussionmentioning

confidence: 98%

“…Experiments with [2-14C]acetate and [UL-14C]leucine show that incorporation of 14C into protein is also enhanced when glucose is present, and is inhibited with cycloheximide. Sahulka et al (1975) have shown that glucose (or sucrose) enhances the levels of NR recovered from excised pea roots but has no effect on the incorporation of [l*C]leucine. In their experiments data on the uptake of [14C]leucine is not given.…”

Section: Effect Of Glucose and Inhibitors Of Rna And Protein Synthesimentioning

confidence: 99%

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Enzymes of nitrogen assimilation in maize roots

Oaks

Stulen

Jones

et al. 1980

Planta

110

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The enzymes nitrate reductase (NR), glutamate dehydrogenase (GDH), glutamate synthase (GOGAT), glutamine synthetase (GS) and asparagine synthetase (AS) have been assayed in various regions along the seedling root ofZea mays L. In the intact attached root and calculated on a protein basis NR, GOGAT, and GS are found to have slightly higher specific activities in the apical 5 mm than in more mature regions of the root. GDH and AS, on the other hand, are much more active in extracts prepared from mature regions of the root than in the apical region. In excised root tips incubated in the presence of NH4 (+) and NO3 (-) there was a marked increase in GDH and AS, and a slight decrease in GOGAT and GS. Additions of NO3 (-) are required for NR activity but neither NO3 (-) nor NH4 (+) additions altered the activity levels of the other four enzymes. Additions of glucose to the medium inhibited the development of AS and GDH activities and resulted in higher activity levels of NR, GS and GOGAT. Glucose additions also enhanced the incorporation of acetate-(14)C and leucine-(14)C into protein. Additions of cycloheximide inhibit the development of NR, AS and GDH activities and also the incorporation of acetate-(14)C and leucine into protein.

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Section: Discussionmentioning

confidence: 66%

Section: Discussionmentioning

confidence: 98%

Section: Effect Of Glucose and Inhibitors Of Rna And Protein Synthesimentioning

confidence: 99%

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Enzymes of nitrogen assimilation in maize roots

Oaks

Stulen

Jones

et al. 1980

Planta

110

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“…These studies indicate that chloroplastic GDH is distinct from mitochondrial GDH, although data from different species are vastly different for NAD/NADP‐activity dependence ratios, K m 's and other parameters. There have been few reports to date on the effects of carbohydrates on the activity of GDH in photosynthetic organisms, although it has been reported that sucrose and glucose decrease Pisum root GDH activity (Sahulka et al 1975). In that light has a general stimulative effect on GDH activity in green tissues (Vankova et al .…”

Section: Introductionmentioning

confidence: 99%

Glutamate Dehydrogenase Activity in Lemna perpusilla 6746: The Effects of Sucrose, Glucose and Fructose Addition to Growth Media

Duke

Koukkari

1977

Physiologia Plantarum

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Lemna perpusilla Torr, strain 6746 clones were maintained under conditions of continuous illumination with various concentrations of sucrose, glucose or fructose added to the growth, medium. After two weeks of growth, plants were harvested and either assayed for total glutamate dehydrogenase activity or fractionated into one chloroplast‐rich and one mitochondria‐rich preparation and then assayed for glutamate dehydrogenase activity. In all assays for glutamate dehydrogenase it was necessary to add bovine serum albumin to the extraction medium in order to obtain sufficient enzyme activity for accurate and reproducible results. The presence of sucrose in the growth medium reduced glutamate dehydrogenase activity in all studies. When samples containing intact organelles were assayed, sucrose inhibition of activity appeared to occur primarily in the chloroplast fraction. Glucose, on the other hand, increased glutamate dehydrogenase activity in the chloroplast‐rich fractions. Upon freeze‐thawing differences between the various treatments were less obvious. The results from these studies indicate possible differences in sugar uptake and/or utilization in Lemna perpusilla.

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“…It is reasonable to infer that the enzyme from non-photosynthetic tissues is similar in this respect, and NADH was found to support nitrate reduction in unpurified extracts from barley roots (Miflin, 1967, pea roots : Sarkissian & Fowler, 1974Sahulka, Gaudinova & Hadacova, 1975), wheat embryos and maize scutellum (Eisner, Hucklesby & Hageman, 1971;, but not in apple roots (Grasmanis & Nicholas, 1967;Frith, 1972). Measurements on a variety of aerobic tissues (Effer&Ranson, 1967;Weissman,'l972a;Radin, 1973;Faiz-ur-Rahman, Trewavas & Davies, 1974) suggest that the intracellular concentration of NADH (approximately 20-200 ^mol dm \ averaged over the cytoplasmic volume only) is generally sufficient to saturate the pyridine nueleotide binding site of NADH-nitrate reductase, which has a Km (NADH) of approximately 2-8 /imol dm~^ (Table 2-purified enzyme from higher plants).…”

Section: (3) Electron Donors For Nitrate Reductasementioning

confidence: 99%

Sources of reductant for nitrate assimilation in non‐photosynthetic tissue: a review

Lee¹

1980

Plant Cell & Environment

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Potential sources of reductant for the pathway of nitrate assimilation in non-photosynthetic tissue are considered in terms of the intracellular distribution of the enzymes involved (relative to those of nitrate assimilation), their maximum catalytic capacity, the availability of their respective substrates, and the form in which the reductant is produced. According to these criteria, the principal sources appear to be the reactions catalysed by NAD-glyceraldehyde-3-phosphate dehydrogenase. glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, NAD-malate dehydrogenase and NADP-malic enzyme. Mitochondrial metabolism may also make a limited contribution, although the evidence is inconclusive. The capacity to generate reductant by carbohydrate oxidation within the proplastids appears insufficient to meet the demand, and an infiux of reducing power from the cytoplasm in the form of dihydroxy acetone phosphate may be necessary to support nitrite reduction and the glutamate synthase reaction which occur there.

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Regulation of Glutamate Dehydrogenase and Nitrate Reductase Levels in Excised Pea Roots by Exogeneously Supplied Sugar

Cited by 31 publications

References 22 publications

Enzymes of nitrogen assimilation in maize roots

Enzymes of nitrogen assimilation in maize roots

Glutamate Dehydrogenase Activity in Lemna perpusilla 6746: The Effects of Sucrose, Glucose and Fructose Addition to Growth Media

Sources of reductant for nitrate assimilation in non‐photosynthetic tissue: a review

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