Regulation of enzymes involved in inorganic N metabolism in pea roots

1981 ◽  
pp. 119-121
Author(s):  
Josef Sahulka
Keyword(s):  
Inorganic N ◽  
N Metabolism ◽  
Pea Roots

Highly Specialized Nitrogen Metabolism in a Freshwater Phytoplankter, Chrysochromulina breviturrita

1987 ◽  
Vol 44 (4) ◽  
pp. 736-742 ◽  
Author(s):  
John D. Wehr ◽  
Lewis M. Brown ◽  
Kathryn O'Grady
Keyword(s):  
Nitrogen Metabolism ◽  
Laboratory Culture ◽  
Organic N ◽  
Acidic Precipitation ◽  
Inorganic N ◽  
Culture Study ◽  
N Source ◽  
Softwater Lakes ◽  
N Metabolism ◽  
N Compounds

A field and laboratory culture study was carried out on the nitrogen metabolism of isolates of the freshwater phytoplankter Chrysochromulina breviturrita Nich. (Prymnesiophyceae). These were isolated from two different softwater lakes, one believed to be influenced by acidic precipitation (Cinder Lake) and another which was experimentally acidified with H2SO4 (Lake 302-South). The alga was able to utilize only NH4+ as an inorganic N source. A range of irradiances and molybdenum concentrations failed to induce NO3− utilization. Among 17 organic N compounds including amino acids, purines, and other amines, only urea plus Ni2+ as a cofactor would serve as the sole N source for this species. Nonetheless, growth rates in media supplied with urea were significantly less than with NH4+. Field data from Lake 302-S indicate that a predominance of NH4+ versus NO3− as the major inorganic N species may have favored the development of a Chrysochromulina-dominated community during August 1984. A detailed depth profile also indicated that a metalimnetic peak (> 20 × 106 cells/L) of this alga coincided with a distinct NH4+ depletion, which occurred at no other time during the year. Experiments with isolates of C. breviturrita and a Nannochloris sp. (Chlorophyceae) (~ 1 μm in diameter) from this community indicated that the former alga possessed a highly specialized N metabolism much like the Cinder Lake isolate. The Nannochloris sp. from the same environment grew on NO3− and NH4+ equally well. It is suggested that the specialized NH4+ utilization by C. breviturrita may itself influence the pH regime of poorly buffered waters through selective NH4+ uptake and H+ generation.

scholarly journals IN VITRO NITROGEN METABOLISM AND ORGANOGENESIS OF NICOTIANA TABACUM

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1121c-1121
Author(s):  
Victoria E. Rudolph ◽  
David W. Burger
Keyword(s):  
Solid Medium ◽  
N Uptake ◽  
Dry Weight ◽  
Inorganic N ◽  
Net Uptake ◽  
History Of ◽  
N Metabolism ◽  
The Media

The role of N metabolism in organogenesis and growth was studied using tobacco pith callus. Callus was cultured on a solid medium containing 10 μM (1.75 mg/l) IAA and 2 μM (0.43 mg/l) kinetin for 56 days. In the growth experiment, ratios of NH4+-N to NO3--N (0:60, 20:40, 30:30, 40:20 and 60:0 mM) were supplied by (NH4)2 SO4 and KNO3. Callus and media were analyzed for inorganic N. Callus supported by 30:30 and 40:20 media removed the highest amounts of NH4+-N and NO3--N from the media and exhibited organogenesis. Final dry weight was greatest in callus supported by the 30:30 medium. In the organogenesis experiment, the transfer history of the inoculum source affected N uptake, organogenesis and growth. Inorganic N was supplied by NH4NO3 and KNO3-. The net uptake of NH4+-N and NO3--N was lower in shoot-forming than in root-forming and non-organogenic callus subculture from 7-day-old stock cultures. The final pH of the medium supporting shoot-forming callus was lowest. Growth, on a dry weight basis, was lowest in shoot-forming callus. Callus subculture from 60-day-old stock cultures formed no shoots.

scholarly journals Photosynthesis and Nitrogen Metabolism of Nepenthes alata in Response to Inorganic NO3- and Organic Prey N in the Greenhouse

ISRN Botany ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Jie He ◽  
Ameerah Zain
Keyword(s):  
Nitrogen Metabolism ◽  
Photosynthetic Pigments ◽  
Photosynthetic Capacity ◽  
Organic N ◽  
Relative Importance ◽  
Light Saturation ◽  
Leaf Lamina ◽  
Inorganic N ◽  
Light Utilization ◽  
N Metabolism

This study investigates the relative importance of leaf carnivory on Nepenthes alata by studying the effect of different nitrogen (N) sources on its photosynthesis and N metabolism in the greenhouse. Plants were given either inorganic NO3-, organic N derived from meal worms, Tenebrio molitor, or both NO3- and organic N for a period of four weeks. Leaf lamina (defined as leaves) had significant higher photosynthetic pigments and light saturation for photosynthesis compared to that of modified leaves (defined as pitchers). Maximal light saturated photosynthetic rates (Pmax) were higher in leaves than in pitchers. Leaves also had a higher light utilization than that of pitchers. Both leaves and pitchers of plants that were supplied with both inorganic NO3- and organic prey N had a similar photosynthetic capacity and N metabolism compared to plants that were given only inorganic NO3-. However, adding organic prey N to the pitchers enhanced both photosynthetic capacity and N metabolism when plants were grown under NO3- deprivation condition. These findings suggest that organic prey N is essential for N. alata to achieve higher photosynthetic capacity and N metabolism only when plants are subjected to an environment where inorganic N is scarce.

scholarly journals A 1232 bp upstream sequence of glutamine synthetase 1b from Eichhornia crassipes is a root-preferential promoter sequence

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yanshan Zhong ◽  
Xiaodan Lu ◽  
Zhiwei Deng ◽  
Ziqing Lu ◽  
Minghui Fu
Keyword(s):  
Glutamine Synthetase ◽  
Eichhornia Crassipes ◽  
Invasive Plant ◽  
Promoter Sequence ◽  
Regulatory Mechanisms ◽  
Pcr Analysis ◽  
Regulation Mechanism ◽  
Upstream Sequence ◽  
Specific Expression ◽  
N Metabolism

Abstract Background Glutamine synthetase (GS) acts as a key enzyme in plant nitrogen (N) metabolism. It is important to understand the regulation of GS expression in plant. Promoters can initiate the transcription of its downstream gene. Eichhornia crassipes is a most prominent aquatic invasive plant, which has negative effects on environment and economic development. It also can be used in the bioremediation of pollutants present in water and the production of feeding and energy fuel. So identification and characterization of GS promoter in E. crassipes can help to elucidate its regulation mechanism of GS expression and further to control its N metabolism. Results A 1232 bp genomic fragment upstream of EcGS1b sequence from E. crassipes (EcGS1b-P) has been cloned, analyzed and functionally characterized. TSSP-TCM software and PlantCARE analysis showed a TATA-box core element, a CAAT-box, root specific expression element, light regulation elements including chs-CMA1a, Box I, and Sp1 and other cis-acting elements in the sequence. Three 5′-deletion fragments of EcGS1b upstream sequence with 400 bp, 600 bp and 900 bp length and the 1232 bp fragment were used to drive the expression of β-glucuronidase (GUS) in tobacco. The quantitative test revealed that GUS activity decreased with the decreasing of the promoter length, which indicated that there were no negative regulated elements in the EcGS1-P. The GUS expressions of EcGS1b-P in roots were significantly higher than those in leaves and stems, indicating EcGS1b-P to be a root-preferential promoter. Real-time Quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) analysis of EcGS1b gene also showed higher expression in the roots of E.crassipes than in stems and leaves. Conclusions EcGS1b-P is a root-preferential promoter sequence. It can specifically drive the transcription of its downstream gene in root. This study will help to elucidate the regulatory mechanisms of EcGS1b tissue-specific expression and further study its other regulatory mechanisms in order to utilize E.crassipes in remediation of eutrophic water and control its overgrowth from the point of nutrient metabolism.

scholarly journals Inorganic Nitrogen Production and Removal along the Sediment Gradient of a Stormwater Infiltration Basin

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 320
Author(s):  
Qianyao Si ◽  
Mary G. Lusk ◽  
Patrick W. Inglett
Keyword(s):  
Removal Efficiency ◽  
N Mineralization ◽  
Inorganic Nitrogen ◽  
Dry Season ◽  
Pollutant Removal ◽  
Net N Mineralization ◽  
Wet Season ◽  
Inorganic N ◽  
N Removal ◽  
Stormwater Infiltration

Stormwater infiltration basins (SIBs) are vegetated depressions that collect stormwater and allow it to infiltrate to underlying groundwater. Their pollutant removal efficiency is affected by the properties of the soils in which they are constructed. We assessed the soil nitrogen (N) cycle processes that produce and remove inorganic N in two urban SIBs, with the goal of further understanding the mechanisms that control N removal efficiency. We measured net N mineralization, nitrification, and potential denitrification in wet and dry seasons along a sedimentation gradient in two SIBs in the subtropical Tampa, Florida urban area. Net N mineralization was higher in the wet season than in the dry season; however, nitrification was higher in the dry season, providing a pool of highly mobile nitrate that would be susceptible to leaching during periodic dry season storms or with the onset of the following wet season. Denitrification decreased along the sediment gradient from the runoff inlet zone (up to 5.2 μg N/g h) to the outermost zone (up to 3.5 μg N/g h), providing significant spatial variation in inorganic N removal for the SIBs. Sediment accumulating around the inflow areas likely provided a carbon source, as well as maintained stable anaerobic conditions, which would enhance N removal.

Ammonium application mitigates the effects of elevated carbon dioxide on the carbon/nitrogen balance of Phoebe bournei seedlings

2021 ◽  
Author(s):  
Xiao Wang ◽  
Xiaoli Wei ◽  
Gaoyin Wu ◽  
Shengqun Chen
Keyword(s):  
Carbon Dioxide ◽  
Enzyme Activities ◽  
Atmospheric Carbon Dioxide ◽  
Global Climate ◽  
Co2 Concentration ◽  
Rubisco Activase ◽  
Plant Responses ◽  
N Metabolism ◽  
C And N ◽  
Phoebe Bournei

Abstract The study of plant responses to increases in atmospheric carbon dioxide (CO2) concentration is crucial to understand and to predict the effect of future global climate change on plant adaptation and evolution. Increasing amount of nitrogen (N) can promote the positive effect of CO2, while how N forms would modify the degree of CO2 effect is rarely studied. The aim of this study was to determine whether the amount and form of nitrogen (N) could mitigate the effects of elevated CO2 (eCO2) on enzyme activities related to carbon (C) and N metabolism, the C/N ratio, and growth of Phoebe bournei (Hemsl.) Y.C. Yang. One-year-old P. bournei seedlings were grown in an open-top air chamber under either an ambient CO2 (aCO2) (350 ± 70 μmol•mol−1) or an eCO2 (700 ± 10 μmol•mol−1) concentration and cultivated in soil treated with either moderate (0.8 g per seedling) or high applications (1.2 g per seedling) of nitrate or ammonium. In seedlings treated with a moderate level of nitrate, the activities of key enzymes involved in C and N metabolism (i.e., Rubisco, Rubisco activase and glutamine synthetase) were lower under eCO2 than under aCO2. By contrast, key enzyme activities (except GS) in seedlings treated with high nitrate or ammonium were not significantly different between aCO2 and eCO2 or higher under eCO2 than under aCO2. The C/N ratio of seedlings treated with moderate or high nitrate under eCO2was significantly changed compared with the seedlings grown under aCO2, whereas the C/N ratio of seedlings treated with ammonium was not significantly different between aCO2 and eCO2. Therefore, under eCO2, application of ammonium can be beneficial C and N metabolism and mitigate effects on the C/N ratio.

scholarly journals N METABOLISM IN THE PUERPERIUM

1927 ◽  
Vol 73 (1) ◽  
pp. 27-40
Author(s):  
Victor John Harding ◽  
Richard Clifton Montgomery
Keyword(s):  
N Metabolism

scholarly journals Macro- and Micronutrient Cycling and Crucial Linkages to Geochemical Processes in Mangrove Ecosystems

2021 ◽  
Vol 9 (5) ◽  
pp. 456
Author(s):  
Daniel M. Alongi
Keyword(s):  
Transformation Process ◽  
Early Diagenesis ◽  
P Availability ◽  
Geochemical Processes ◽  
Nutrient Cycles ◽  
Physiological Mechanisms ◽  
Retention Efficiency ◽  
Mangrove Ecosystems ◽  
N Metabolism ◽  
Transformation Processes

High mangrove productivity is sustained by rapid utilization, high retention efficiency and maximum storage of nutrients in leaves, roots, and soils. Rapid microbial transformations and high mineralization efficiencies in tandem with physiological mechanisms conserve scarce nutrients. Macronutrient cycling is interlinked with micronutrient cycling; all nutrient cycles are linked closely to geochemical transformation processes. Mangroves can be N-, P-, Fe-, and Cu-limited; additions of Zn and Mo stimulate early growth until levels above pristine porewater concentrations induce toxicity. Limited nutrient availability is caused by sorption and retention onto iron oxides, clays, and sulfide minerals. Little N is exported as immobilization is the largest transformation process. Mn and S affect N metabolism and photosynthesis via early diagenesis and P availability is coupled to Fe-S redox oscillations. Fe is involved in nitrification, denitrification and anammox, and Mo is involved in NO3− reduction and N2-fixation. Soil Mg, K, Mn, Zn and Ni pool sizes decrease as mangrove primary productivity increases, suggesting increasing uptake and more rapid turnover than in less productive forests. Mangroves may be major contributors to oceanic Mn and Mo cycles, delivering 7.4–12.1 Gmol Mn a−1 to the ocean, which is greater than global riverine input. The global Mo import rate by mangroves corresponds to 15–120% of Mo supply to the oceanic Mo budget.

Glutamine or glutamate release by the liver constitutes a major mechanism for nitrogen salvage

1997 ◽  
Vol 272 (2) ◽  
pp. G257-G264 ◽  
Author(s):  
C. Remesy ◽  
C. Moundras ◽  
C. Morand ◽  
C. Demigne
Keyword(s):  
Digestive Tract ◽  
Glutamate Release ◽  
Casein Diet ◽  
Postprandial Period ◽  
Major Mechanism ◽  
Low Protein ◽  
N Utilization ◽  
N Metabolism ◽  
Glutamine Synthesis ◽  
Negative Balance

The aim of the present study was to investigate mechanisms of N salvage by the liver when a diet is protein deficient. For this purpose, rats were adapted to a slightly deficient (11% casein) or moderately surfeit (22% casein) dietary protein level. Animals were sampled during the postprandial or the postabsorptive period, and fluxes across the digestive tract and liver were determined. During the postabsorptive period there was a negative balance of glutamine across the digestive tract in both diet groups. During the postprandial period the digestive balance of glutamine was still negative, despite a substantial supply of dietary glutamine and glutamate, suggesting that glutamine utilization is maximal during this period. There was a net production of glutamate and glutamine by the liver in both diet groups, but glutamine release was 73% higher in rats fed the low-protein diet. In these animals, because of the relatively low capacity of ureagenesis, N utilization was shifted toward glutamine synthesis: overall uptake of amino acids by the liver was approximately 5.3 micromol/min, and net release of glutamine + glutamate was approximately 2.9 micromol/min (hence a 55% cycling, on a molar basis). This cycling was only 12% in rats adapted to the 22% casein diet. When liver ammonia uptake was taken into account, N cycling showed parallel changes: 64% or 15% in rats adapted to the 11% or 22% casein diet, respectively. Besides glutamine delivery, glutamate was also released by the liver, representing an N source for extrasplanchnic tissues. With protein-deficient diets, hepatic glutamine delivery mainly serves to fulfill substrate needs for intestinal metabolism, which represents a mechanism for N salvage. This shift of N metabolism from urea toward glutamine production may imply a glutamate transfer from periportal to glutamine-synthesizing perivenous hepatocytes.

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