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.

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).

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.

scholarly journals Reduction of nitrates in Cucumis sativus L. seedlings I. Influence of tungsten and vanadium on absorption and reduction of nitrates

2014 ◽  
Vol 49 (3) ◽  
pp. 259-267 ◽  
Author(s):  
Józef Buczek ◽  
Ewa Kowalińska ◽  
Krystyna Kuczera
Keyword(s):  
Nitrate Reductase ◽  
Cucumis Sativus ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Plant Tissues ◽  
Inhibiting Activity ◽  
Cucumis Sativus L ◽  
Cucumber Seedlings

Investigations were conducted on the influence of tungsten (Na<sub>2</sub>WO<sub>4</sub>) and meta-vanadate (NaVO<sub>3</sub>) on uptake and reduction of nitrates by cucumber seedlings. Tungsten and vanadium almost completely inhibited nitrate reductase activity (NR) after treating the plants for 24 hours with nitrates in the presence of 10<sup>-4</sup> M WO<sub>4</sub><sup>-2</sup> and 10<sup>-3</sup> M VO<sub>3</sub><sup>-</sup>. Uptake of NO<sub>3</sub><sup>-</sup> in the presence of WO<sub>4</sub><sup>-2</sup> in this same period of time was lowered by about 50 %, while in the presence of VO<sub>3</sub><sup>-</sup> by seventy percent. The ratio of NO<sub>3</sub><sup>-</sup> absorbed to that reducted in control plants was around 3, whereas in the presence of WO<sub>4</sub><sup>-2</sup> and VO<sub>3</sub><sup>-</sup> 9 and 8 respectively. The effect of NR inhibiting activity by WO<sub>4</sub><sup>-2</sup> and VO<sub>3</sub><sup>-</sup> was significant but somewhat weaker if both inhibitors were applied to the plants 24 hours after formation of the NR system, whereas NO<sub>3</sub><sup>-</sup> uptake was subject to a slight lowering. The above data suggest that WO<sub>4</sub><sup>-2</sup> and VO<sub>3</sub><sup>-</sup> after a 24 hour application of these inhibitors to plants, primary inhibit biosynthesis and activity of NR and to a lesser extent effect NO<sub>3</sub><sup>-</sup> absorption. On the basis of results reached the Butz and Jackson (1977) hypothesis concerning the model of NO<sub>3</sub><sup>-</sup> uptake and reduction by plant tissues is discussed.

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.

scholarly journals Influence of simazine on nitrate uptake and nitrate reductase activity in Triticum aestivum (L.) and Cucumis sativus (L.) seedlings

2014 ◽  
Vol 53 (2) ◽  
pp. 247-256 ◽  
Author(s):  
Irena Jarzyńska ◽  
Józef Buczek
Keyword(s):  
Triticum Aestivum ◽  
Nitrate Reductase ◽  
Cucumis Sativus ◽  
Nitrate Uptake ◽  
Reductase Activity ◽  
Triticum Aestivum L ◽  
Probable Mechanism ◽  
Cucumis Sativus L ◽  
Photosynthesis Inhibition ◽  
Nr Activity

The influence of simazine (2-chloro-4,6-bis(ethylamine)-1,3,5-triazine) on N0<sub>3</sub>- uptake and nitrate reductase (NR) activity in wheat (<em>Triticum aestivum</em>) and cucumber (<em>Cucumis sativus</em>) seedlings was investigated. It was found that at first (up to 12 h after herbicide treatment) simazine enhanced and then inhibited NR activity in the leaves and roots of the tested plants. After seven days of growth in nutrient medium containing 2.5 and 25 µM simazine the herbicide inhibited by 25 and 70 per cent, respectively, NR activity and reduced by 30 per cent in wheat and 50 per cent in cucumber seedlings nitrate uptake. The probable mechanism of NR inhibition by simazin is discussed and it is suggested that the influence of the herbicide on NR activity may not be exclusively connected with photosynthesis inhibition.

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 The effect of ionic and non-ionic surfactants on the growth, nitrate reductase and nitrite reductase activities of Spirodela polyrrhiza (L.) Schleiden

2014 ◽  
Vol 53 (4) ◽  
pp. 551-559 ◽  
Author(s):  
Józef Buczek
Keyword(s):  
Nitrate Reductase ◽  
Nitrite Reductase ◽  
Soluble Protein ◽  
Dry Mass ◽  
Ionic Surfactants ◽  
Plant Tissues ◽  
Spirodela Polyrrhiza ◽  
Nr Activity

Inclusion into the medium of 5 mg•dm<sup>-3</sup> of non-ionic (ENF) or ionic (DBST) surfactant caused 50-60% inhibition of nitrite reductase MR) activity in <em>S. polyrrhiza</em>. At the same time, increased accumulation of NO<sub>2</sub>- in the plant tissues and lowering of the total and soluble protein contents were found. DBST also lowered the nitrate reductase (NR) activity and the dry mass of the plants.

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 Nitrate reductase activity in the diatom Biddulphia longicmris: characterization and daily oscillation

1995 ◽  
Vol 43 (2) ◽  
pp. 123-128 ◽  
Author(s):  
Cristina S Asano ◽  
Pio Colepicolo ◽  
Elizabeth Aidar
Keyword(s):  
Nitrate Reductase ◽  
Reductase Activity ◽  
Ph Dependence ◽  
Marine Diatom ◽  
Nitrogen Deprivation ◽  
The Times ◽  
Nr Activity ◽  
Daily Oscillation

Nitrate reductase (NR) activity was studied in the marine diatom Biddulphia longicmris. During 24 hours of sampling, NR activity was found during day time and in the transition day-night. Nitrite anions, the product of nitrate reduction, was released by the cells at the times NR was active, and accumulated in the culture medium. Whenever the cultures of B. longicmris were submitted to nitrogen deprivation, NR activity could not be detected. In vitro determination of KM values for NR using nitrate or NADH were respectively 50//M and 80 /*M. Temperature and pH dependence of NR activity were also determined for this organism.

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.

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