scholarly journals Inhibition of nitrate reductase and ATPase activities in Zea mays roots by tungsten and N, N'-dicyclohexylcarbodiimide

2014 ◽  
Vol 50 (3) ◽  
pp. 455-464
Author(s):  
Józef Buczek ◽  
Marek Burzyński ◽  
Anna Suder-Moraw
Keyword(s):  
Zea Mays ◽  
Nitrate Reductase ◽  
Nutrient Solution ◽  
Additional Mechanism ◽  
Corn Roots ◽  
Membrane Bound ◽  
Nr Activity

The activity of soluble and membrane-bound ATPase obtained from corn roots was in vivo markedly inhibited by N,N' -dicyclohexylcanbodiimide (DCCD) and W0<sub>4</sub><sup>2-</sup> ions. DCCD (2.5 X 10<sup>-5</sup> M) added to the nutrient solution strongly decreased in vivo nitrate reductase (NR) activity after 12-h growth of plants while it had no effect in experiments <em>in vitro</em> on NR activity. Tungsten in a concentration of 10<sup>-4</sup> M completely blocked NR activity after 24 h. In the above used concentrations neither DCCD nor W0<sub>4</sub><sup>2-</sup> inhibited completely N0<sub>3</sub><sup>-</sup> absorption by corn roots. The results suggest that there must exist in corn roots another or an additional mechanism of N0<sub>3</sub><sup>-</sup> assimilation apart from of that proposed by Butz and Jackson (1977).

scholarly journals Nitrate reductase and acid phosphatase activities as affected by inorganic phosphate in corn roots

2014 ◽  
Vol 52 (1) ◽  
pp. 77-86 ◽  
Author(s):  
Marie Kummerova ◽  
Józef Buczek
Keyword(s):  
Acid Phosphatase ◽  
Nitrate Reductase ◽  
Nutrient Solution ◽  
Inorganic Phosphate ◽  
Acid Phosphatases ◽  
Weak Effect ◽  
Corn Roots ◽  
Nr Activity

The deficieny of inorganic phosphate in nutrient solution reduces by about 50 per cent NO<sub>3</sub>- absorption in corn seedlings, it decreases both <em>in vitro</em> and in vivo nitrate reductase (NR) activity, as well the potential and actual NR level and has a very weak effect on NR induction. Acid phosphatases activities increase in corn roots when the plants are grown in nutrient solution without phosphorus. We suggest that inorganic phosphate is required mainly for maintenance of NR activity rather, than for induction <em>in vivo</em> of nitrate reductase. It is not excluded that deficiency of inorganic phosphate in root tissue may be partly supplemented as the result of enhanced acid phosphatase activity.

In vivo Nitrate Reductase Activity in Leaves of Pearl Millet, Pennisetum americanum (L.) Leeke

1987 ◽  
Vol 14 (2) ◽  
pp. 125 ◽  
Author(s):  
SV Chanda ◽  
AK Joshi ◽  
PN Krishnan ◽  
YD Singh
Keyword(s):  
Nitrate Reductase ◽  
Reductase Activity ◽  
Potassium Phosphate ◽  
Limiting Factor ◽  
Growth Stages ◽  
In Vivo Assay ◽  
Rate Limiting ◽  
Nr Activity

In the in vivo assay of nitrate reductase (NR) in P. americanum leaves, addition of 1% (v/v) Triton X-100, potassium phosphate buffer (80 mM, pH 7.4) and 1.13 mM NADH to the assay medium resulted in maximum activity. With increasing concentration of NADH, saturation-type kinetics were observed. Based on this data metabolic pool concentration for NADH and apparent Km for nitrate reductase were determined. In field studies with cultivars BJ-104, J-104 and 5141-A of P. americanum, the relative limitation of NO3-, NADH and nitrate reductase in NO3- assimilation was determined. NR activity was measured by four modifications of the in vivo assay technique (with NO3-, with NADH, without NO3- and NADH and with both NO3- and NADH additions to the reaction mixture) and with one in vitro technique. For all the cultivars, NADH was the major rate-limiting factor for in vivo assay during early growth stages, while at later stages, NO3- was limiting. At no stage was NR rate-limiting. It is concluded that NR activity alone may not serve as biochemical marker for improved efficiency of utilisation of nitrogen in P. americanum.

Nitrogen-metabolizing enzymes of Diplodia maydis, a Zea mays L. stalk rot causing fungus

1979 ◽  
Vol 25 (2) ◽  
pp. 167-169
Author(s):  
James B. Bussard ◽  
Russell L. Larson
Keyword(s):  
Zea Mays ◽  
Nitrate Reductase ◽  
Nitrogen Metabolism ◽  
Zea Mays L ◽  
Ammonium Salts ◽  
Higher Plant ◽  
Stalk Rot ◽  
Relationship Of

The nitrogen source available to Diplodia maydis in vivo is reported to affect the severity of stalk rot in maize. Nitrate and (or) ammonium salts were tested for their effect on the type of nitrogen metabolism found in Diplodia maydis in vitro. The level of glutamate dehydrogenase remained essentially constant on either nitrogen salt but nitrate reductase was induced by growth on nitrate salts and was not extractable on ammonium salts. Properties of nitrate reductase reported here are similar to those reported for the higher plant and Neurospora crassa enzymes. The relationship of nitrogen metabolism in Diplodia maydis to Zea mays L. stalk rot is discussed.

scholarly journals The role of light in the inducation of nitrate reductase and nitrite reductase in cucumber seedlings

2015 ◽  
Vol 45 (1–2) ◽  
pp. 77-92 ◽  
Author(s):  
J. Buczek
Keyword(s):  
Nitrate Reductase ◽  
Nitrite Reductase ◽  
De Novo ◽  
Activity Level ◽  
Induction Medium ◽  
Cucumber Seedlings ◽  
Nr Activity

The activity of nitrate reductase (NR) and nitrite reductase (NiR) was investigated in vivo and in vitro in the roots and NR activity in 3-day-old cotyledons of cucumber seedlings. NR activity in the roots appears almost immediately after addition of nitrate ions to the induction medium, whereas, in the cotyledones NR induction is delayed. In general light enhances NR activity in the cotyledons and depresses it in the roots in experiments of short duration. Etiolation of the cotyledons reduces NR activity in the roots and leads to disappearance of the activity of this enzyme in the cotyledons, whereas the NR activity of roots kept in darkness, after transfer of the etiolated plants to light, increases threefold. In roots growing in darkness a delay in NiR induction is observed, while in those growing in ligth it occurs at the same time as NR induction. Chlormaphenicol (CAP), cycloheximide (CHI) and actinomycin D (ACM) applied at the beginning of the period of seedling induction with initrates inhibit NR activity in the cotyledons, whereas in the roots only CHI and ACM exert such an effect. To sum up, NR is synthesized in cucumber roots and cotyledons de novo on the cytoplasmic polyribosomes, and light per se is not indispensable for this synthesis, but it has an indirect influence on the activity level of NR and NiR both in the roots and the cotyledons.

scholarly journals Activation of nitrate reductase of cashew leaf by exogenous nitrite

2002 ◽  
Vol 14 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Ricardo Almeida Viégas ◽  
Joaquim Albenísio Gomes Silveira
Keyword(s):  
Nitrate Reductase ◽  
Reaction Medium ◽  
No Oxidation ◽  
Primary Metabolism ◽  
Leaf Extracts ◽  
Enzymatic Extract ◽  
Regulation Mechanisms ◽  
Nr Activity

Nitrate reductase (NR) plays a central role in plant primary metabolism and exhibits complex regulation mechanisms for its catalytic activity. There is controversy in the literature concerning the possible direct effect of NO2- on the stimulation and/or activation of NR activity. The influence of NO2- was studied on the NR activity in the leaves of 30-day-old cashew (Anacardium occidentale L.) seedlings. Addition of NO2- to the reaction mixture containing leaf enzymatic extract resulted in a remarkable increase in NR activity. A trace amount (5 mumol.L-1) of NO2- was required to achieve full NR activity. The in vitro NR-activity showed a steady time-dependent increase when incubated in the presence of only NO3- + NO2-. In contrast, in vitro NR activity was practically absent in a NO2- -free reaction medium, even in the presence of a saturating NO3- concentration. No oxidation of NO2- to NO3- was detected during the experiment. Although NO2- clearly activated the in vitro NR activity, it had no effect on the in vivo leaf-NR activity determined under absence of oxygen. NADH at concentrations greater than 0.5 mmol.L-1 decreased the rates of in vitro NR activity. These results indicated, at least partially, a strong cashew leaf NO2- dependency of NR activation and/or activity. Finally, based on these results, it is suggested that this singular NR activity model induced by exogenous NO2- in cashew leaf extracts is caused by changes in the NR activation state by NO2- itself.

scholarly journals Genetic and biochemical analysis of intragenic complementation events among nitrate reductase apoenzyme-deficient mutants of Nicotiana plumbaginifolia.

Genetics ◽  
1991 ◽  
Vol 127 (1) ◽  
pp. 199-204 ◽  
Author(s):  
F Pelsy ◽  
M Gonneau
Keyword(s):  
Nitrate Reductase ◽  
Molecular Data ◽  
Nicotiana Plumbaginifolia ◽  
Wild Type Plant ◽  
Catalytic Domains ◽  
Intragenic Complementation ◽  
In The Wild ◽  
Nr Activity

Abstract Intragenic complementation has been observed between apoenzyme nitrate reductase-deficient mutants (nia) of Nicotiana plumbaginifolia. In vivo as in vitro, the NADH-nitrate reductase (NR) activity in plants heterozygous for two different nia alleles was lower than in the wild type plant, but the plants were able to grow on nitrate as a sole nitrogen source. NR activity, absent in extracts of homozygous nia mutants was restored by mixing extracts from two complementing nia mutants. These observations suggest that NR intragenic complementation results from either the formation of heteromeric NR or from the interaction between two modified enzymes. Complementation was only observed between mutants retaining different partial catalytic activities of the enzyme. Results are in agreement with molecular data suggesting the presence of three catalytic domains in the subunit of the enzyme.

scholarly journals Reduction of nitrates in Cucumis sativus L. seedlings II. Influence of tungsten and vanadium on nitrate reductase and adenosine triphosphatase activities

2014 ◽  
Vol 49 (3) ◽  
pp. 269-280 ◽  
Author(s):  
Józef Buczek
Keyword(s):  
Nitrate Reductase ◽  
Enzyme System ◽  
Plant Tissues ◽  
Additional Mechanism ◽  
Cucumis Sativus L ◽  
Simultaneous Reduction ◽  
Reduction Of No ◽  
Initial Stage ◽  
Nr Activity

ATPases isolated from the roots of cucumber seedlings activated by Mg<sup>+2</sup> ions in experiments in vitro, were fairly distinctly inhibited by Ca<sup>-2</sup> ions, very slightly inhibited by fluorides and molybdenum ions while NO<sub>3</sub><sup>-</sup> anions had no effect on the level of ATPase activity studied. Introduction into the nutrient of 10<sup>-4</sup> M Na<sub>2</sub>WO<sub>4</sub> or 10<sup>-3</sup> M Na VO<sub>3</sub> (inhibitors of nitrate reductase NR) distinctly inhibited activity of the ATPase under study especially of fractions IIa and III, and inhibited NR activity and lowered uptake of NO<sub>3</sub><sup>-</sup>. WO<sub>4</sub><sup>-2</sup> and VO<sub>3</sub><sup></sup> inhibited to the same extent absorption and reduction of NO<sub>3</sub><sup>-</sup> in the initial phase of NR induction, whereas at a later stage both inhibitors checked reduction to a greater degree than uptake of NO<sub>3</sub><sup>-</sup>. The results indicate the possibility of certain ATPase participation in assimilating nitrates, and suggest that in the initial stage of biosynthesis of the NR enzyme system, activity of the enzyme is distinctly dependent upon NO<sub>3</sub><sup>-</sup> transport and the level of NR activity limited by the amount of nitrate taken up. At a later an additional mechanism of NO<sub>3</sub><sup>-</sup> transport probably functions, not connected with simultaneous reduction of nitrates. On the basis of results the Butz and Jackson (1977) hypothesis concerning a model for the absorption and reduction of NO<sub>3</sub><sup>-</sup> by plant tissues is discussed.

Effect of R-25788 on EPTC Metabolism in Corn(Zea mays)

Weed Science ◽  
1978 ◽  
Vol 26 (2) ◽  
pp. 167-171 ◽  
Author(s):  
R. D. Carringer ◽  
C. E. Rieck ◽  
L. P. Bush
Keyword(s):  
Zea Mays ◽  
Nutrient Solution ◽  
Water Soluble ◽  
Glutathione Synthetase ◽  
Synthetase Activity ◽  
Oxidized Glutathione ◽  
Corn Roots ◽  
Reduced And Oxidized Glutathione ◽  
Stimulation Of

R-25788(N,N-diallyl-2,2-dichloroacetamide) had no effect on14CO2evolution from carbonyl-14C-EPTC(S-ethyl dipropylthiocarbamate) treated corn(Zea maysL. ‘inbred Oh551’). Treatment with 1.0 ppmw R-25788 increased production of water-soluble and unextractable products from EPTC and increased the rate of disappearance of organic-soluble radioactivity. R-25788 increased levels of reduced and oxidized glutathione in corn roots. Pretreatment of corn in nutrient solution with R-25788 had no effect on glutathione synthetase activity in root tissue, but R-25788 at 5.0 and 500.0 nM showed an in vitro stimulation of the enzyme.

Half-Life of Platelet Factor 4 (PF-4) in Plasma and Platelets from Macaca Mulatta

1977 ◽  
Vol 37 (01) ◽  
pp. 073-080 ◽  
Author(s):  
Knut Gjesdal ◽  
Duncan S. Pepper
Keyword(s):  
Macaca Mulatta ◽  
Half Life ◽  
Human Platelet ◽  
Gel Filtration ◽  
Platelet Factor 4 ◽  
Active Protein ◽  
Platelet Factor ◽  
Membrane Bound

SummaryHuman platelet factor 4 (PF-4) showed a reaction of complete identity with PF-4 from Macaca mulatta when tested against rabbit anti-human-PF-4. Such immunoglobulin was used for quantitative precipitation of in vivo labelled PF-4 in monkey serum. The results suggest that the active protein had an intra-platelet half-life of about 21 hours. In vitro 125I-labelled human PF-4 was injected intravenously into two monkeys and isolated by immuno-precipita-tion from platelet-poor plasma and from platelets disrupted after gel-filtration. Plasma PF-4 was found to have a half-life of 7 to 11 hours. Some of the labelled PF-4 was associated with platelets and this fraction had a rapid initial disappearance rate and a subsequent half-life close to that of plasma PF-4. The results are compatible with the hypothesis that granular PF-4 belongs to a separate compartment, whereas membrane-bound PF-4 and plasma PF-4 may interchange.

scholarly journals 68Ga-Radiolabeling and Pharmacological Characterization of a Kit-Based Formulation of the Gastrin-Releasing Peptide Receptor (GRP-R) Antagonist RM2 for Convenient Preparation of [68Ga]Ga-RM2

Pharmaceutics ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1160
Author(s):  
Adrien Chastel ◽  
Delphine Vimont ◽  
Stephane Claverol ◽  
Marion Zerna ◽  
Sacha Bodin ◽  
...  
Keyword(s):  
Calcium Mobilization ◽  
Pharmacological Characterization ◽  
Peptide Receptor ◽  
Gastrin Releasing Peptide ◽  
Production Route ◽  
Membrane Bound ◽  
One Year ◽  
Calcium Mobilization Assay

Background: [68Ga]Ga-RM2 is a potent Gastrin-Releasing Peptide-receptor (GRP-R) antagonist for imaging prostate cancer and breast cancer, currently under clinical evaluation in several specialized centers around the world. Targeted radionuclide therapy of GRP-R-expressing tumors is also being investigated. We here report the characteristics of a kit-based formulation of RM2 that should ease the development of GRP-R imaging and make it available to more institutions and patients. Methods: Stability of the investigated kits over one year was determined using LC/MS/MS and UV-HPLC. Direct 68Ga-radiolabeling was optimized with respect to buffer (pH), temperature, reaction time and shaking time. Conventionally prepared [68Ga]Ga-RM2 using an automated synthesizer was used as a comparator. Finally, the [68Ga]Ga-RM2 product was assessed with regards to hydrophilicity, affinity, internalization, membrane bound fraction, calcium mobilization assay and efflux, which is a valuable addition to the in vivo literature. Results: The kit-based formulation, kept between 2 °C and 8 °C, was stable for over one year. Using acetate buffer pH 3.0 in 2.5–5.1 mL total volume, heating at 100 °C during 10 min and cooling down for 5 min, the [68Ga]Ga-RM2 produced by kit complies with the requirements of the European Pharmacopoeia. Compared with the module production route, the [68Ga]Ga-RM2 produced by kit was faster, displayed higher yields, higher volumetric activity and was devoid of ethanol. In in vitro evaluations, the [68Ga]Ga-RM2 displayed sub-nanomolar affinity (Kd = 0.25 ± 0.19 nM), receptor specific and time dependent membrane-bound fraction of 42.0 ± 5.1% at 60 min and GRP-R mediated internalization of 24.4 ± 4.3% at 30 min. The [natGa]Ga-RM2 was ineffective in stimulating intracellular calcium mobilization. Finally, the efflux of the internalized activity was 64.3 ± 6.5% at 5 min. Conclusion: The kit-based formulation of RM2 is suitable to disseminate GRP-R imaging and therapy to distant hospitals without complex radiochemistry equipment.

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