Nitrate reduction and nitrogenase activity in excised corn roots

1981 ◽  
Vol 59 (12) ◽  
pp. 2445-2449 ◽  
Author(s):  
Pedro Antonio A. Pereira ◽  
José Ivo Baldani ◽  
Johanna Döbereiner ◽  
Carlos A. Neyra
Keyword(s):  
Nitrate Reduction ◽  
Similar Pattern ◽  
Nitrogenase Activity ◽  
Corn Root ◽  
Root Segments ◽  
Corn Roots ◽  
Corn Plants ◽  
Sizable Fraction

Root segments obtained from field-grown corn plants were divided into small sections and assayed for acetylene (C2H2) reduction. After overnight preincubation, C2H2 reduction started immediately and linear rates were observed for several hours. Addition of NO3− (1 mM) delayed the start of C2H2 reduction but linear rates followed thereafter. A similar pattern was observed with excised roots inoculated with Azospirillum lipoferum.Addition of malate did not eliminate the NO3− effect. Inoculation with A. lipoferum resulted in relatively large rates of C2H2 reduction and a shorter lag than normal (4 to 8 h). A transient accumulation of NO2− accompanied the disappearance of NO3− and C2H2 reduction started only after all the NO2− had been reduced. A very sizable fraction of the reduced NO3− and NO2− was accounted for as N2O accumulation. Thus, the results provided support for the in situ operation of both N2 fixation and denitrification in A. lipoferum – corn root associations and it is proposed that mature corn roots are able to provide sufficient carbon to support both processes.

In situ grown Fe3O4 particle on stainless steel: A highly efficient electrocatalyst for nitrate reduction to ammonia

Nano Research ◽  
2021 ◽  
Author(s):  
Xiaoya Fan ◽  
Lisi Xie ◽  
Jie Liang ◽  
Yuchun Ren ◽  
Longcheng Zhang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Nitrate Reduction ◽  
Fe3o4 Particle ◽  
Highly Efficient

Relation Between CO2 Evolution and in situ Reduction of Nitrate in Wheat Leaves

1981 ◽  
Vol 8 (6) ◽  
pp. 515 ◽  
Author(s):  
MS Naik ◽  
DJD Nicholas
Keyword(s):  
Citric Acid ◽  
Nitrate Reduction ◽  
Citric Acid Cycle ◽  
Nitrate Assimilation ◽  
Co2 Evolution ◽  
In Situ Reduction ◽  
Acid Cycle ◽  
Nitrite Production ◽  
Wheat Leaves

In wheat leaf discs the evolution of 14CO2 from exogenously supplied 14C-labelled citric acid cycle intermediates was stimulated during the in situ anaerobic reduction of nitrate in the dark. Under these conditions, however, [1,4-14C]succinate was not metabolized. Similarly, when leaves were allowed to assimilate 14CO2 in the dark, thus producing endogenously labelled organic acids, the subsequent evolution of 14CO2 from discs prepared from these leaves was strongly dependent on nitrate reduction. A 1 : 1 stoichiometry between nitrite production and CO2 evolution was recorded during this in situ reduction of nitrate. The in situ reduction of nitrate was inhibited by malonate and D-malate and this effect was reversed by fumarate, probably by generating L-malate within the mitochondria. Mitochondrial NAD-malic enzyme (decarboxylating) (EC 1.1.1.38) was similarly inhibited competitively by malonate and D-malate, but not by succinate. These results indicate that the citric acid cycle dehydrogenases which generate CO2 supply NADH for nitrate reduction in wheat leaves. It is likely that, under anaerobic conditions, nitrate acts as an alternative oxidant to O2 for the NADH generated by the citric acid cycle dehydrogenases resulting in simultaneous evolution of CO2. This ensures that the citric acid cycle operates at the required rate for nitrate assimilation.

scholarly journals A Study on the Mechanism and Kinetic of Nitrate Reduction by the nZVI-g-C3N4/TiO2  Composite Under the Simulated Sunlight

2021 ◽  
Author(s):  
Linyu Wei ◽  
Jing Tian ◽  
Qing Wang ◽  
Yuanyuan Liu ◽  
Yi Yu ◽  
...  
Keyword(s):  
Nitrate Reduction ◽  
Reduction Method ◽  
Nitrate Removal ◽  
Simulated Sunlight ◽  
Photoelectric Properties ◽  
Phase Reduction ◽  
Reduction Efficiency ◽  
Initial Ph ◽  
Lamp System

Abstract g-C3N4/TiO2 composite has excellent photoelectric properties and is considered as a good carrier of nanoparticles. A novel composite of nZVI-g-C3N4/TiO2 was successfully synthesized through in-situ growth nZVI on the surface of g-C3N4/TiO2 with liquid phase reduction method. The composite was characterized by TEM, XRD, EDS and evaluated its nitrate removal efficiency. The effects of composite dosage, solution initial pH and HCOOH concentration on nitrate reduction were investigated. The results showed that nitrate was rapidly reduced by nZVI-g-C3N4/TiO2 composite. The dosage of 4 g/L nZVI-g-C3N4/TiO2 composite and 3.0 mM of HCOOH concentration was more suitable for nitrate reduction. Solution initial pH had little impact on the nitrate reduction efficiency, but affected the proportion of the nitrate reduction products. The mechanism of nitrate reduction in the nZVI-gC3N4/TiO2/HCOOH-Xe-lamp system was proposed. The nZVI-gC3N4/TiO2 composite could be considered as a viable and promising technology for water pollution remediation.

Assimilation and dissimilation of fatty acids by the rat liver

1959 ◽  
Vol 196 (6) ◽  
pp. 1238-1241 ◽  
Author(s):  
Y. Stein ◽  
B. Shapiro
Keyword(s):  
Fatty Acids ◽  
Linoleic Acid ◽  
Palmitic Acid ◽  
Blood Plasma ◽  
Similar Pattern ◽  
Blood Substitutes ◽  
Triglyceride Fraction ◽  
Liver Triglycerides ◽  
Maximum Retention

Up to 60% of i.v. injected doses of 1-C14 palmitic acid was found in the liver 15 minutes after injection, two thirds in the form of triglycerides and the rest as phospholipids. Almost no radioactive UFA could be demonstrated in the liver or in blood plasma. Thereafter, the activity in the triglyceride fraction fell rapidly, only 50% remaining after 1 hour. At the same time the phospholipid activity increased. With 1-C14 linoleic acid a similar pattern was found, except that the percentage retained in the liver was lower and maximum retention was found after 5 minutes. Fifteen minutes after injection of 1-C14 palmitate most of the radioactive glycerides in the liver were found in the microsomes and mitochondria, with very little in the floating fat. Equilibration between these cytoplasmatic particles occurred only after 2 hours. Perfusion of the liver in situ with blood or blood substitutes, after various periods following 1-C14 palmitic acid injection, caused a release of about 5–20% of the liver triglycerides and 0.5–2% of the liver phospholipids per hour.

Field measurements of nitrogenase activity in soils amended with wheat straw

1983 ◽  
Vol 34 (6) ◽  
pp. 725 ◽  
Author(s):  
MM Roper
Keyword(s):  
Nitrogenase Activity ◽  
New South ◽  
Field Measurements ◽  
Field Capacity ◽  
Nitrogen Fertilizers ◽  
Free Living ◽  
Straw Decomposition ◽  
Indirect Measure ◽  
South Wales

Nitrogenase activity and decomposition of straw were examined in situ in two areas (Gunnedah and Cowra) representative of large areas of the New South Wales wheat belt. Measurements of nitrogenase activity were made by adapting the acetylene reduction assay for use in the field. Evolution of CO2 was monitored as an indirect measure of decomposition of straw. The addition of straw to soil stimulated nitrogenase activity which was related to the amount of straw added and the rate of straw decomposition. There were significant levels of activity provided the soil was moist and warm. Nitrogenase activity increased with mean daily soil temperature (up to at least 30�C) and decreased as the soil dried from field capacity. It is concluded that nitrogen fixation by free-living nitrogen-fixing microorganisms in soils amended with straw may contribute to the nitrogen status of the soil and thus reduce the need for nitrogen fertilizers.

Nitrogen fixation (acetylene reduction) by lines composing 'Park' Kentucky bluegrass

1986 ◽  
Vol 32 (4) ◽  
pp. 348-352
Author(s):  
Keuk-Ki Lee ◽  
Robert C. Shearman ◽  
Robert V. Klucas
Keyword(s):  
Root Exudates ◽  
Nitrogenase Activity ◽  
Soluble Sugar ◽  
Kentucky Bluegrass ◽  
Selected Lines ◽  
Field Inoculation ◽  
Nitrogenase Activities ◽  
Highly Correlated ◽  
Hydroponically Grown

Response of 'Park' Kentucky bluegrass to inoculation with Klebsiella pneumoniae strain W-6 was tested under field conditions. Field inoculation did not increase nitrogenase activity measured in situ, but did increase the nitrogenase activity as measured using an excised root assay which included a 10-h incubation before the addition of acetylene. Fifteen lines composing 'Park' were grown in fritted-clay medium, inoculated with soil, and compared for nitrogenase activities using the excised roots assay. Significant differences were observed between two lines. Six lines were selected from the 15 lines, grown hydroponically, inoculated with soil, and assayed for nitrogenase activity using intact 105-day-old plants. Nitrogenase activities were immediately detectable and increased curvilinearly. Differences in nitrogenase activities among the six lines were detected within 1 h and significant differences were evident in 4 h. The six selected lines were also tested for levels of anthrone-reactive sugars in roots and root exudates of hydroponically grown plants. Significant differences were detected in levels of sugars in roots but not in root exudates. Possible correlations were sought among and within the three different experiments involving the six selected lines. With hydroponically grown plants, nitrogenase activities during the first 4 h were highly correlated with those after 24 h incubation. Correlations were found between nitrogenase activities in excised roots and soluble sugar concentrations in root tissue and root exudates.

Nitrogenase activity associated with Zostera marina from a North Carolina estuary

1982 ◽  
Vol 28 (4) ◽  
pp. 448-451 ◽  
Author(s):  
Garriet W. Smith ◽  
Steven S. Hayasaka
Keyword(s):  
North Carolina ◽  
Zostera Marina ◽  
Nitrogenase Activity ◽  
Growth Period ◽  
Winter Period ◽  
Late Winter ◽  
Active Growth ◽  
North Carolina Estuary ◽  
Active Growth Period

Nitrogenase activity (at in situ temperatures) associated with Zostera marina reflected the active growth periods of this plant in North Carolina coastal waters. During the plants most active growth period (late winter – spring) nitrogenase activity was primarily rhizospheric (8.47 μmol nitrogen fixed∙m−2∙day−1), while during its fall – early winter period it was primarily phyllospheric (8.03 μmol nitrogen fixed∙m−2∙day−1). No nitrogenase activity was detected during the warmer summer months when the plant is dormant. Phyllospheric nitrogenase activity (possibly the result of epiphytic heterocystic blue-green bacteria) was highest when plants were incubated aerobically in the presence of light.

A survey of angiosperms in Nova Scotia for rhizosphere nitrogenase (acetylene-reduction) activity

1978 ◽  
Vol 56 (18) ◽  
pp. 2218-2223 ◽  
Author(s):  
D. Smith ◽  
D. G. Patriquin
Keyword(s):  
Nova Scotia ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Reduction Technique ◽  
Acetylene Reduction Activity ◽  
Forage Grasses ◽  
Reduction Activity ◽  
Tropical Forage ◽  
Poorly Drained Soils

Excised root samples from 901 plants, representing 130 species of nonnodulated angiosperms largely in upland, pioneering habitats, were assayed for nitrogenase activity by the acetylene-reduction technique after overnight preincubation of the samples under low pO2. Most samples and most species exhibited very low excised root acetylene-reducing activities, but for 19 species, maximum values were greater than 50 nmol C2H4∙g−1∙h−1. In situ C2H2 assays, conducted on 10 species which had exhibited maximum excised root activities greater than 10 nmol C2H4∙g−1∙h−1, indicated average belowground N2-fixation rates of 3 to 92 g N∙ha−1∙day−1 and maxima greater than 100 g N∙ha−1∙day−1 for 3 of the 10 species. The highest values were for grasses characteristic of poorly drained soils and for some dicotyledonous weeds. It is concluded that the potential of temperate-zone angiosperms for nitrogenase activity by 'associative symbioses' approaches that of tropical forage grasses.

Sign in / Sign up

Export Citation Format

Share Document