Science.gov

Sample records for affects nitrogen metabolism

  1. Plant maturity and nitrogen fertilization affected fructan metabolism in harvestable tissues of timothy (Phleum pratense L.).

    PubMed

    Ould-Ahmed, Marouf; Decau, Marie-Laure; Morvan-Bertrand, Annette; Prud'homme, Marie-Pascale; Lafrenière, Carole; Drouin, Pascal

    2014-10-15

    Timothy (Phleum pratense L.) is an important grass forage used for pasture, hay, and silage in regions with cool and humid growth seasons. One of the factors affecting the nutritive value of this grass is the concentration of non-structural carbohydrates (NSC), mainly represented by fructans. NSC concentration depends on multiple factors, making it hardly predictable. To provide a better understanding of NSC metabolism in timothy, the effects of maturity stage and nitrogen (N) fertilization level on biomass, NSC and N-compound concentrations were investigated in the tissues used for forage (leaf blades and stems surrounded by leaf sheaths) of hydroponically grown plants. Moreover, activities and relative expression level of enzymes involved in fructan metabolism were measured in the same tissues. Forage biomass was not altered by the fertilization level but was strongly modified by the stage of development. It increased from vegetative to heading stages while leaf-to-stem biomass ratio decreased. Total NSC concentration, which was not altered by N fertilization level, increased between heading and anthesis due to an accumulation of fructans in leaf blades. Fructan metabolizing enzyme activities (fructosyltransferase-FT and fructan exohydrolase-FEH) were not or only slightly altered by both maturity stage and N fertilization level. Conversely, the relative transcript levels of genes coding for enzymes involved in fructan metabolism were modified by N supply (PpFT1 and Pp6-FEH1) or maturity stage (PpFT2). The relative transcript level of PpFT1 was the highest in low N plants while that of Pp6-FEH1 was the highest in high N plants. Morevoer, transcript level of PpFT1 was negatively correlated with nitrate concentration while that of PpFT2 was positively correlated with sucrose concentration. This distinct regulation of the two genes coding for 6-sucrose:fructan fructosyltransferase (6-SFT) may allow a fine adequation of C allocation towards fructan synthesis in

  2. Developmental changes in carbon and nitrogen metabolism affect tea quality in different leaf position.

    PubMed

    Li, Zhi-Xin; Yang, Wei-Jun; Ahammed, Golam Jalal; Shen, Chen; Yan, Peng; Li, Xin; Han, Wen-Yan

    2016-09-01

    Leaf position represents a specific developmental stage that influences both photosynthesis and respiration. However, the precise relationships between photosynthesis and respiration in different leaf position that affect tea quality are largely unknown. Here, we show that the effective quantum yield of photosystem II [ΦPSⅡ] as well as total chlorophyll concentration (TChl) of tea leaves increased gradually with leaf maturity. Moreover, respiration rate (RR) together with total nitrogen concentration (TN) decreased persistently, but total carbon remained unchanged during leaf maturation. Analyses of major N-based organic compounds revealed that decrease in TN was attributed to a significant decrease in the concentration of caffeine and amino acids (AA) in mature leaves. Furthermore, soluble sugar (SS) decreased, but starch concentration increased with leaf maturity, indicating that source-sink relationship was altered during tea leaf development. Detailed correlation analysis showed that ΦPSⅡ was negatively correlated with RR, SS, starch, tea polyphenol (TP), total catechins and TN, but positively correlated with TChl; while RR was positively correlated with TN, SS, TP and caffeine, but negatively correlated with TChl and starch concentrations. Our results suggest that biosynthesis of chlorophyll, catechins and polyphenols is closely associated with photosynthesis and respiration in different leaf position that greatly influences the relationship between primary and secondary metabolism in tea plants.

  3. Roostocks/Scion/Nitrogen Interactions Affect Secondary Metabolism in the Grape Berry.

    PubMed

    Habran, Aude; Commisso, Mauro; Helwi, Pierre; Hilbert, Ghislaine; Negri, Stefano; Ollat, Nathalie; Gomès, Eric; van Leeuwen, Cornelis; Guzzo, Flavia; Delrot, Serge

    2016-01-01

    The present work investigates the interactions between soil content, rootstock, and scion by focusing on the effects of roostocks and nitrogen supply on grape berry content. Scions of Cabernet Sauvignon (CS) and Pinot Noir (PN) varieties were grafted either on Riparia Gloire de Montpellier (RGM) or 110 Richter (110R) rootstock. The 4 rooststock/scion combinations were fertilized with 3 different levels of nitrogen after fruit set. Both in 2013 and 2014, N supply increased N uptake by the plants, and N content both in vegetative and reproductory organs. Rootstock, variety and year affected berry weight at harvest, while nitrogen did not affect significantly this parameter. Grafting on RGM consistently increased berry weight compared to 110R. PN consistently produced bigger berries than CS. CS berries were heavier in 2014 than in 2013, but the year effect was less marked for PN berries. The berries were collected between veraison and maturity, separated in skin and pulp, and their content was analyzed by conventional analytical procedures and untargeted metabolomics. For anthocyanins, the relative quantitation was fairly comparable with both LC-MS determination and HPLC-DAD, which is a fully quantitative technique. The data show complex responses of the metabolite content (sugars, organic acids, amino acids, anthocyanins, flavonols, flavan-3-ols/procyanidins, stilbenes, hydroxycinnamic, and hydroxybenzoic acids) that depend on the rootstock, the scion, the vintage, the nitrogen level, the berry compartment. This opens a wide range of possibilities to adjust the content of these compounds through the choice of the roostock, variety and nitrogen fertilization.

  4. Roostocks/Scion/Nitrogen Interactions Affect Secondary Metabolism in the Grape Berry

    PubMed Central

    Habran, Aude; Commisso, Mauro; Helwi, Pierre; Hilbert, Ghislaine; Negri, Stefano; Ollat, Nathalie; Gomès, Eric; van Leeuwen, Cornelis; Guzzo, Flavia; Delrot, Serge

    2016-01-01

    The present work investigates the interactions between soil content, rootstock, and scion by focusing on the effects of roostocks and nitrogen supply on grape berry content. Scions of Cabernet Sauvignon (CS) and Pinot Noir (PN) varieties were grafted either on Riparia Gloire de Montpellier (RGM) or 110 Richter (110R) rootstock. The 4 rooststock/scion combinations were fertilized with 3 different levels of nitrogen after fruit set. Both in 2013 and 2014, N supply increased N uptake by the plants, and N content both in vegetative and reproductory organs. Rootstock, variety and year affected berry weight at harvest, while nitrogen did not affect significantly this parameter. Grafting on RGM consistently increased berry weight compared to 110R. PN consistently produced bigger berries than CS. CS berries were heavier in 2014 than in 2013, but the year effect was less marked for PN berries. The berries were collected between veraison and maturity, separated in skin and pulp, and their content was analyzed by conventional analytical procedures and untargeted metabolomics. For anthocyanins, the relative quantitation was fairly comparable with both LC-MS determination and HPLC-DAD, which is a fully quantitative technique. The data show complex responses of the metabolite content (sugars, organic acids, amino acids, anthocyanins, flavonols, flavan-3-ols/procyanidins, stilbenes, hydroxycinnamic, and hydroxybenzoic acids) that depend on the rootstock, the scion, the vintage, the nitrogen level, the berry compartment. This opens a wide range of possibilities to adjust the content of these compounds through the choice of the roostock, variety and nitrogen fertilization. PMID:27555847

  5. Nitrogen-Sparing Mechanisms in Chlamydomonas Affect the Transcriptome, the Proteome, and Photosynthetic Metabolism[W

    PubMed Central

    Schmollinger, Stefan; Mühlhaus, Timo; Boyle, Nanette R.; Blaby, Ian K.; Casero, David; Mettler, Tabea; Moseley, Jeffrey L.; Kropat, Janette; Sommer, Frederik; Strenkert, Daniela; Hemme, Dorothea; Pellegrini, Matteo; Grossman, Arthur R.; Stitt, Mark; Schroda, Michael; Merchant, Sabeeha S.

    2014-01-01

    Nitrogen (N) is a key nutrient that limits global primary productivity; hence, N-use efficiency is of compelling interest in agriculture and aquaculture. We used Chlamydomonas reinhardtii as a reference organism for a multicomponent analysis of the N starvation response. In the presence of acetate, respiratory metabolism is prioritized over photosynthesis; consequently, the N-sparing response targets proteins, pigments, and RNAs involved in photosynthesis and chloroplast function over those involved in respiration. Transcripts and proteins of the Calvin-Benson cycle are reduced in N-deficient cells, resulting in the accumulation of cycle metabolic intermediates. Both cytosolic and chloroplast ribosomes are reduced, but via different mechanisms, reflected by rapid changes in abundance of RNAs encoding chloroplast ribosomal proteins but not cytosolic ones. RNAs encoding transporters and enzymes for metabolizing alternative N sources increase in abundance, as is appropriate for the soil environmental niche of C. reinhardtii. Comparison of the N-replete versus N-deplete proteome indicated that abundant proteins with a high N content are reduced in N-starved cells, while the proteins that are increased have lower than average N contents. This sparing mechanism contributes to a lower cellular N/C ratio and suggests an approach for engineering increased N-use efficiency. PMID:24748044

  6. Nitrogen-Sparing Mechanisms in Chlamydomonas Affect the Transcriptome, the Proteome, and Photosynthetic Metabolism.

    PubMed

    Schmollinger, Stefan; Mühlhaus, Timo; Boyle, Nanette R; Blaby, Ian K; Casero, David; Mettler, Tabea; Moseley, Jeffrey L; Kropat, Janette; Sommer, Frederik; Strenkert, Daniela; Hemme, Dorothea; Pellegrini, Matteo; Grossman, Arthur R; Stitt, Mark; Schroda, Michael; Merchant, Sabeeha S

    2014-04-01

    Nitrogen (N) is a key nutrient that limits global primary productivity; hence, N-use efficiency is of compelling interest in agriculture and aquaculture. We used Chlamydomonas reinhardtii as a reference organism for a multicomponent analysis of the N starvation response. In the presence of acetate, respiratory metabolism is prioritized over photosynthesis; consequently, the N-sparing response targets proteins, pigments, and RNAs involved in photosynthesis and chloroplast function over those involved in respiration. Transcripts and proteins of the Calvin-Benson cycle are reduced in N-deficient cells, resulting in the accumulation of cycle metabolic intermediates. Both cytosolic and chloroplast ribosomes are reduced, but via different mechanisms, reflected by rapid changes in abundance of RNAs encoding chloroplast ribosomal proteins but not cytosolic ones. RNAs encoding transporters and enzymes for metabolizing alternative N sources increase in abundance, as is appropriate for the soil environmental niche of C. reinhardtii. Comparison of the N-replete versus N-deplete proteome indicated that abundant proteins with a high N content are reduced in N-starved cells, while the proteins that are increased have lower than average N contents. This sparing mechanism contributes to a lower cellular N/C ratio and suggests an approach for engineering increased N-use efficiency.

  7. Nitrogen metabolism in haloarchaea

    PubMed Central

    Bonete, María José; Martínez-Espinosa, Rosa María; Pire, Carmen; Zafrilla, Basilio; Richardson, David J

    2008-01-01

    The nitrogen cycle (N-cycle), principally supported by prokaryotes, involves different redox reactions mainly focused on assimilatory purposes or respiratory processes for energy conservation. As the N-cycle has important environmental implications, this biogeochemical cycle has become a major research topic during the last few years. However, although N-cycle metabolic pathways have been studied extensively in Bacteria or Eukarya, relatively little is known in the Archaea. Halophilic Archaea are the predominant microorganisms in hot and hypersaline environments such as salted lakes, hot springs or salted ponds. Consequently, the denitrifying haloarchaea that sustain the nitrogen cycle under these conditions have emerged as an important target for research aimed at understanding microbial life in these extreme environments. The haloarchaeon Haloferax mediterranei was isolated 20 years ago from Santa Pola salted ponds (Alicante, Spain). It was described as a denitrifier and it is also able to grow using NO3-, NO2- or NH4+ as inorganic nitrogen sources. This review summarizes the advances that have been made in understanding the N-cycle in halophilic archaea using Hfx mediterranei as a haloarchaeal model. The results obtained show that this microorganism could be very attractive for bioremediation applications in those areas where high salt, nitrate and nitrite concentrations are found in ground waters and soils. PMID:18593475

  8. Nitrogen Source and External Medium pH Interaction Differentially Affects Root and Shoot Metabolism in Arabidopsis

    PubMed Central

    Sarasketa, Asier; González-Moro, M. Begoña; González-Murua, Carmen; Marino, Daniel

    2016-01-01

    Ammonium nutrition often represents an important growth-limiting stress in plants. Some of the symptoms that plants present under ammonium nutrition have been associated with pH deregulation, in fact external medium pH control is known to improve plants ammonium tolerance. However, the way plant cell metabolism adjusts to these changes is not completely understood. Thus, in this work we focused on how Arabidopsis thaliana shoot and root respond to different nutritional regimes by varying the nitrogen source (NO3- and NH4+), concentration (2 and 10 mM) and pH of the external medium (5.7 and 6.7) to gain a deeper understanding of cell metabolic adaptation upon altering these environmental factors. The results obtained evidence changes in the response of ammonium assimilation machinery and of the anaplerotic enzymes associated to Tricarboxylic Acids (TCA) cycle in function of the plant organ, the nitrogen source and the degree of ammonium stress. A greater stress severity at pH 5.7 was related to NH4+ accumulation; this could not be circumvented in spite of the stimulation of glutamine synthetase, glutamate dehydrogenase, and TCA cycle anaplerotic enzymes. Moreover, this study suggests specific functions for different gln and gdh isoforms based on the nutritional regime. Overall, NH4+ accumulation triggering ammonium stress appears to bear no relation to nitrogen assimilation impairment. PMID:26870054

  9. Induced lung inflammation and dietary protein supply affect nitrogen retention and amino acid metabolism in growing pigs.

    PubMed

    Kampman-van de Hoek, Esther; Sakkas, Panagiotis; Gerrits, Walter J J; van den Borne, Joost J G C; van der Peet-Schwering, Carola M C; Jansman, Alfons J M

    2015-02-14

    It is hypothesised that during immune system activation, there is a competition for amino acids (AA) between body protein deposition and immune system functioning. The aim of the present study was to quantify the effect of immune system activation on N retention and AA metabolism in growing pigs, depending on dietary protein supply. A total of sixteen barrows received an adequate (Ad) or restricted (Res) amount of dietary protein, and were challenged at day 0 with intravenous complete Freund's adjuvant (CFA). At days - 5, 3 and 8, an irreversible loss rate (ILR) of eight AA was determined. CFA successfully activated the immune system, as indicated by a 2- to 4-fold increase in serum concentrations of acute-phase proteins (APP). Pre-challenge C-reactive protein concentrations were lower (P< 0·05) and pre- and post-challenge albumin tended to be lower in Res-pigs. These findings indicate that a restricted protein supply can limit the acute-phase response. CFA increased urinary N losses (P= 0·04) and tended to reduce N retention in Ad-pigs, but not in Res-pigs (P= 0·07). The ILR for Val was lower (P= 0·05) at day 8 than at day 3 in the post-challenge period. The ILR of most AA, except for Trp, were strongly affected by dietary protein supply and positively correlated with N retention. The correlations between the ILR and APP indices were absent or negative, indicating that changes in AA utilisation for APP synthesis were either not substantial or more likely outweighed by a decrease in muscle protein synthesis during immune system activation in growing pigs.

  10. Lotus corniculatus condensed tannins decrease in vivo populations of proteolytic bacteria and affect nitrogen metabolism in the rumen of sheep.

    PubMed

    Min, B R; Attwood, G T; Reilly, K; Sun, W; Peters, J S; Barry, T N; McNabb, W C

    2002-10-01

    Condensed tannins in forage legumes improve the nutrition of sheep by reducing ruminal degradation of plant protein and increasing crude protein flow to the intestine. However, the effects of condensed tannins in forage legumes on rumen bacterial populations in vivo are poorly understood. The aim of this study was to investigate the specific effects of condensed tannins from Lotus corniculatus on four proteolytic rumen bacteria in sheep during and after transition from a ryegrass (Lolium perenne)-white clover (Trifolium repens) diet (i.e., low condensed tannins) to a Lotus corniculatus diet (i.e., higher condensed tannins). The bacterial populations were quantified using a competitive polymerase chain reaction. Lotus corniculatus was fed with or without ruminal infusions of polyethylene glycol (PEG), which binds to and inactivates condensed tannins, enabling the effect of condensed tannins on bacterial populations to be examined. When sheep fed on ryegrass-white clover, populations of Clostridium proteoclasticum B316T, Butyrivibrio fibrisolvens C211a, Eubacterium sp. C12b, and Streptococcus bovis B315 were 1.5 x 10(8), 1.1 x 10(6), 4.6 x 10(8), and 7.1 x 10(6) mL(-1), respectively. When the diet was changed to Lotus corniculatus, the average populations (after 8-120 h) of C. proteoclasticum, B. fibrisolvens, Eubacterium sp., and S. bovis decreased (P < 0.001) to 2.4 x 10(7), 1.1 x 10(5), 1.1 x 10(8), and 2.5 x 10(5) mL(-1), respectively. When PEG was infused into the rumen of sheep fed Lotus corniculatus, the populations of C. proteoclasticum, B. fibrisolvens, Eubacterium sp., and S. bovis were higher (P < 0.01-0.001) than in sheep fed Lotus corniculatus without the PEG infusion, with average populations (after 8-120 h) of 4.9 x 10(7), 3.8 x 10(5), 1.9 x 10(8), and 1.0 x 10(6), respectively. Sheep fed the Lotus corniculatus diet had lower rumen proteinase activity, ammonia, and soluble nitrogen (P < 0.05-0.001) than sheep that were fed Lotus corniculatus plus PEG

  11. Peripheral and splanchnic metabolism of dietary nitrogen are differently affected by the protein source in humans as assessed by compartmental modeling.

    PubMed

    Fouillet, Hélène; Mariotti, François; Gaudichon, Claire; Bos, Cécile; Tomé, Daniel

    2002-01-01

    We used a previously developed compartmental model to assess the postprandial distribution and metabolism of dietary nitrogen (N) in the splanchnic and peripheral areas after the ingestion of a single mixed meal containing either (15)N-labeled milk or soy purified protein. Although the lower whole-body retention of dietary N from soy protein was measured experimentally, the splanchnic retention of dietary N was predicted by the model not to be affected by the protein source, and its incorporation into splanchnic proteins was predicted to reach approximately 35% of ingested N at 8 h after both meals. However, dietary N intestinal absorption and its appearance in splanchnic free amino acids were predicted to be more rapid from soy protein and were associated with a higher deamination, concomitant with a higher efficiency of incorporation of dietary N into proteins in the splanchnic bed. In contrast, soy protein was predicted to cause a reduction in peripheral dietary N uptake, as a consequence of both similar splanchnic retention and increased oxidation compared with milk protein. In addition, protein synthesis efficiency was reduced in the peripheral area after soy protein intake, leading to dietary N incorporation in peripheral proteins that fell from 26 to 19% of ingested N 8 h after milk and soy protein ingestion, respectively. Such a model thus enables a description of the processes involved in the differential metabolic utilization of dietary proteins and constitutes a valuable tool for further definition of the notion of protein quality during the period of protein gain.

  12. The overexpression of the pine transcription factor PpDof5 in Arabidopsis leads to increased lignin content and affects carbon and nitrogen metabolism.

    PubMed

    Rueda-López, Marina; Cañas, Rafael A; Canales, Javier; Cánovas, Francisco M; Ávila, Concepción

    2015-12-01

    PpDof 5 is a regulator of the expression of glutamine synthetase (GS; EC 6.3.1.2) genes in photosynthetic and non-photosynthetic tissues of maritime pine. We have used Arabidopsis thaliana as a model system to study PpDof 5 function in planta, generating transgenic lines overexpressing the pine transcription factor. The overexpression of PpDof 5 resulted in a substantial increase of lignin content with a simultaneous regulation of carbon and nitrogen key genes. In addition, partitioning in carbon and nitrogen compounds was spread via various secondary metabolic pathways. These results suggest pleiotropic effects of PpDof 5 expression on various metabolic pathways of carbon and nitrogen metabolism. Plants overexpressing PpDof 5 exhibited upregulation of genes encoding enzymes for sucrose and starch biosynthesis, with a parallel increase in the content of soluble sugars. When the plants were grown under nitrate as the sole nitrogen source, they exhibited a significant regulation of the expression of genes involved mainly in signaling, but similar growth rates to wild-type plants. However, plants grown under ammonium exhibited major induction of the expression of photosynthetic genes and differential expression of ammonium and nitrate transporters. All these data suggest that in addition to controlling ammonium assimilation, PpDof 5 could be also involved in the regulation of other pathways in carbon and nitrogen metabolism in pine trees.

  13. Nitrogen regulation of fungal secondary metabolism in fungi

    PubMed Central

    Tudzynski, Bettina

    2014-01-01

    Fungi occupy diverse environments where they are constantly challenged by stressors such as extreme pH, temperature, UV exposure, and nutrient deprivation. Nitrogen is an essential requirement for growth, and the ability to metabolize a wide variety of nitrogen sources enables fungi to colonize different environmental niches and survive nutrient limitations. Favored nitrogen sources, particularly ammonium and glutamine, are used preferentially, while the expression of genes required for the use of various secondary nitrogen sources is subject to a regulatory mechanism called nitrogen metabolite repression. Studies on gene regulation in response to nitrogen availability were carried out first in Saccharomyces cerevisiae, Aspergillus nidulans, and Neurospora crassa. These studies revealed that fungi respond to changes in nitrogen availability with physiological and morphological alterations and activation of differentiation processes. In all fungal species studied, the major GATA transcription factor AreA and its co-repressor Nmr are central players of the nitrogen regulatory network. In addition to growth and development, the quality and quantity of nitrogen also affects the formation of a broad range of secondary metabolites (SMs). Recent studies, mainly on species of the genus Fusarium, revealed that AreA does not only regulate a large set of nitrogen catabolic genes, but can also be involved in regulating production of SMs. Furthermore, several other regulators, e.g., a second GATA transcription factor, AreB, that was proposed to negatively control nitrogen catabolic genes by competing with AreA for binding to GATA elements, was shown to act as activator of some nitrogen-repressed as well as nitrogen-induced SM gene clusters. This review highlights our latest understanding of canonical (AreA-dependent) and non-canonical nitrogen regulation mechanisms by which fungi may regulate biosynthesis of certain SMs in response to nitrogen availability. PMID:25506342

  14. The Nitrogen Excretory Metabolism of Lumbricus Terrestris

    ERIC Educational Resources Information Center

    Teal, A. R.

    1977-01-01

    The use of the earthworm as a laboratory animal for studying the effect of starvation on nitrogen metabolism is discussed. Simple techniques and methods are presented allowing in vivo physiological responses to be compared with changes in the enzyme potential of gut tissue. (Author/MA)

  15. Nitrogen metabolism and excretion during aestivation.

    PubMed

    Ip, Y K; Chew, S F

    2010-01-01

    In this chapter, up-to-date information on nitrogen metabolism and excretion in various aestivators is presented. Although aestivation involves long-term fasting and corporal torpor, adaptive responses with regard to excretory nitrogen metabolism exhibited by aestivators during aestivation differ from those exhibited by nonaestivators undergoing fasting or immobilization. Special efforts were made to address current issues pertaining to excretory nitrogen metabolism and related phenomena in aestivators. Adaptations exhibited by aestivators were discussed in relation to the induction, maintenance, and arousal phases of aestivation. For the induction phase, we included topics like urea as an internal induction signal for aestivation, alteration in the permeability of the skin to ammonia, and changes in rate of ammonia production and urea synthesis. For the maintenance phase, the emphasis was on protein synthesis and degradation, ammonia production, and urea synthesis and accumulation. For the arousal phase, the focus was on rehydration, urea excretion, and phenomena related to feeding. Adaptations exhibited by aestivators specifically to each of these three phases of aestivation are essential to the understanding of the overall aestivation process, but, at present, only limited information is available on excretory nitrogen metabolism in animals during the induction or arousal phases of aestivation. Therefore, future efforts should be made to identify adaptive responses particular to each of the three phases of aestivation in various aestivators.

  16. Understanding Plant Nitrogen Metabolism through Metabolomics and Computational Approaches

    PubMed Central

    Beatty, Perrin H.; Klein, Matthias S.; Fischer, Jeffrey J.; Lewis, Ian A.; Muench, Douglas G.; Good, Allen G.

    2016-01-01

    A comprehensive understanding of plant metabolism could provide a direct mechanism for improving nitrogen use efficiency (NUE) in crops. One of the major barriers to achieving this outcome is our poor understanding of the complex metabolic networks, physiological factors, and signaling mechanisms that affect NUE in agricultural settings. However, an exciting collection of computational and experimental approaches has begun to elucidate whole-plant nitrogen usage and provides an avenue for connecting nitrogen-related phenotypes to genes. Herein, we describe how metabolomics, computational models of metabolism, and flux balance analysis have been harnessed to advance our understanding of plant nitrogen metabolism. We introduce a model describing the complex flow of nitrogen through crops in a real-world agricultural setting and describe how experimental metabolomics data, such as isotope labeling rates and analyses of nutrient uptake, can be used to refine these models. In summary, the metabolomics/computational approach offers an exciting mechanism for understanding NUE that may ultimately lead to more effective crop management and engineered plants with higher yields. PMID:27735856

  17. Metabolism of nitrogenous compounds by ruminant liver.

    PubMed

    Reynolds, C K

    1992-03-01

    Ruminants absorb substantial amounts of ammonia nitrogen and very little glucose. Ammonia absorbed is removed by the liver and converted to urea, which can be recycled to the digestive tract and add to the pool of ammonia absorbed. When ammonia absorption and liver urea production are increased by changes in nitrogen intake, an associated increase in liver alpha-amino nitrogen removal has been observed. Reasons for the increase in liver removal of amino acids with greater ureagenesis are uncertain, but the aspartate/glutamate requirement of ureagenesis and the complex relationships between ureagenesis and the tricarboxylic acid cycle, glucogenesis, liver energy metabolism and redox state all may be involved. Amino acids represent potential sources of carbon for liver glucogenesis and precise reckonings of the contributions of amino acid carbon to glucogenesis are needed for ruminants fed differing diets. There is evidence for the involvement of peptides in liver nitrogen exchanges and amino acids in peptides represent a potential source of carbon for glucogenesis and nitrogen for ureagenesis. A number of endocrine factors have an impact on liver nitrogen metabolism in ruminants. Growth hormone decreases liver urea release and increases liver glutamate release.

  18. Nitrogen starvation affects bacterial adhesion to soil

    PubMed Central

    Borges, Maria Tereza; Nascimento, Antônio Galvão; Rocha, Ulisses Nunes; Tótola, Marcos Rogério

    2008-01-01

    One of the main factors limiting the bioremediation of subsoil environments based on bioaugmentation is the transport of selected microorganisms to the contaminated zones. The characterization of the physiological responses of the inoculated microorganisms to starvation, especially the evaluation of characteristics that affect the adhesion of the cells to soil particles, is fundamental to anticipate the success or failure of bioaugmentation. The objective of this study was to investigate the effect of nitrogen starvation on cell surface hydrophobicity and cell adhesion to soil particles by bacterial strains previously characterized as able to use benzene, toluene or xilenes as carbon and energy sources. The strains LBBMA 18-T (non-identified), Arthrobacter aurescens LBBMA 98, Arthrobacter oxydans LBBMA 201, and Klebsiella sp. LBBMA 204–1 were used in the experiments. Cultivation of the cells in nitrogen-deficient medium caused a significant reduction of the adhesion to soil particles by all the four strains. Nitrogen starvation also reduced significantly the strength of cell adhesion to the soil particles, except for Klebsiella sp. LBBMA 204–1. Two of the four strains showed significant reduction in cell surface hydrophobicity. It is inferred that the efficiency of bacterial transport through soils might be potentially increased by nitrogen starvation. PMID:24031246

  19. Bottle gourd rootstock-grafting affects nitrogen metabolism in NaCl-stressed watermelon leaves and enhances short-term salt tolerance.

    PubMed

    Yang, Yanjuan; Lu, Xiaomin; Yan, Bei; Li, Bin; Sun, Jin; Guo, Shirong; Tezuka, Takafumi

    2013-05-01

    The plant growth, nitrogen absorption, and assimilation in watermelon (Citrullus lanatus [Thunb.] Mansf.) were investigated in self-grafted and grafted seedlings using the salt-tolerant bottle gourd rootstock Chaofeng Kangshengwang (Lagenaria siceraria Standl.) exposed to 100mM NaCl for 3d. The biomass and NO3(-) uptake rate were significantly increased by rootstock while these values were remarkably decreased by salt stress. However, compared with self-grafted plants, rootstock-grafted plants showed higher salt tolerance with higher biomass and NO3(-) uptake rate under salt stress. Salinity induced strong accumulation of nitrate, ammonium and protein contents and a significant decrease of nitrogen content and the activities of nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), and glutamate synthase (GOGAT) in leaves of self-grafted seedlings. In contrast, salt stress caused a remarkable decrease in nitrate content and the activities of GS and GOGAT, and a significant increase of ammonium, protein, and nitrogen contents and NR activity, in leaves of rootstock-grafted seedlings. Compared with that of self-grafted seedlings, the ammonium content in leaves of rootstock-grafted seedlings was much lower under salt stress. Glutamate dehydrogenase (GDH) activity was notably enhanced in leaves of rootstock-grafted seedlings, whereas it was significantly inhibited in leaves of self-grafted seedlings, under salinity stress. Three GDH isozymes were isolated by native gel electrophoresis and their expressions were greatly enhanced in leaves of rootstock-grafted seedlings than those of self-grafted seedlings under both normal and salt-stress conditions. These results indicated that the salt tolerance of rootstock-grafted seedlings might (be enhanced) owing to the higher nitrogen absorption and the higher activities of enzymes for nitrogen assimilation induced by the rootstock. Furthermore, the detoxification of ammonium by GDH when the GS/GOGAT pathway

  20. Modification of primary and secondary metabolism of potato plants by nitrogen application differentially affects resistance to Phytophthora infestans and Alternaria solani.

    PubMed

    Mittelstrass, K; Treutter, D; Plessl, M; Heller, W; Elstner, E F; Heiser, I

    2006-09-01

    Potato plants ( SOLANUM TUBEROSUM L. cv. Indira) were grown at two levels of N supply in the greenhouse. Plants supplied with 0.8 g N per plant (high N variant) showed significantly increased biomass as compared to plants without additional N fertilisation (low N variant). C/N ratio was lower and protein content was higher in leaves of the high N variant. The concentration of chlorogenic acids and flavonols was significantly lower in leaves from the high N variant. Whereas resistance to ALTERNARIA SOLANI increased when plants were supplied with additional nitrogen, these plants were more susceptible to PHYTOPHTHORA INFESTANS. After infection with both pathogens, we found a strong induction of p-coumaroylnoradrenaline and p-coumaroyloctopamine, which are identified for the first time in potato leaves and are discussed as resistance factors of other solanaceous plants.

  1. Nitrogen Metabolism Genes from Temperate Marine Sediments.

    PubMed

    Reyes, Carolina; Schneider, Dominik; Lipka, Marko; Thürmer, Andrea; Böttcher, Michael E; Friedrich, Michael W

    2017-03-10

    In this study, we analysed metagenomes along with biogeochemical profiles from Skagerrak (SK) and Bothnian Bay (BB) sediments, to trace the prevailing nitrogen pathways. NO3(-) was present in the top 5 cm below the sediment-water interface at both sites. NH4(+) increased with depth below 5 cm where it overlapped with the NO3(-) zone. Steady-state modelling of NO3(-) and NH4(+) porewater profiles indicates zones of net nitrogen species transformations. Bacterial protease and hydratase genes appeared to make up the bulk of total ammonification genes. Genes involved in ammonia oxidation (amo, hao), denitrification (nir, nor), dissimilatory NO3(-) reduction to NH4(+) (nfr and otr) and in both of the latter two pathways (nar, nap) were also present. Results show ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) are similarly abundant in both sediments. Also, denitrification genes appeared more abundant than DNRA genes. 16S rRNA gene analysis showed that the relative abundance of the nitrifying group Nitrosopumilales and other groups involved in nitrification and denitrification (Nitrobacter, Nitrosomonas, Nitrospira, Nitrosococcus and Nitrosomonas) appeared less abundant in SK sediments compared to BB sediments. Beggiatoa and Thiothrix 16S rRNA genes were also present, suggesting chemolithoautotrophic NO3(-) reduction to NO2(-) or NH4(+) as a possible pathway. Our results show the metabolic potential for ammonification, nitrification, DNRA and denitrification activities in North Sea and Baltic Sea sediments.

  2. Urea and Ammonia Metabolism and the Control of Renal Nitrogen Excretion.

    PubMed

    Weiner, I David; Mitch, William E; Sands, Jeff M

    2015-08-07

    Renal nitrogen metabolism primarily involves urea and ammonia metabolism, and is essential to normal health. Urea is the largest circulating pool of nitrogen, excluding nitrogen in circulating proteins, and its production changes in parallel to the degradation of dietary and endogenous proteins. In addition to serving as a way to excrete nitrogen, urea transport, mediated through specific urea transport proteins, mediates a central role in the urine concentrating mechanism. Renal ammonia excretion, although often considered only in the context of acid-base homeostasis, accounts for approximately 10% of total renal nitrogen excretion under basal conditions, but can increase substantially in a variety of clinical conditions. Because renal ammonia metabolism requires intrarenal ammoniagenesis from glutamine, changes in factors regulating renal ammonia metabolism can have important effects on glutamine in addition to nitrogen balance. This review covers aspects of protein metabolism and the control of the two major molecules involved in renal nitrogen excretion: urea and ammonia. Both urea and ammonia transport can be altered by glucocorticoids and hypokalemia, two conditions that also affect protein metabolism. Clinical conditions associated with altered urine concentrating ability or water homeostasis can result in changes in urea excretion and urea transporters. Clinical conditions associated with altered ammonia excretion can have important effects on nitrogen balance.

  3. Effects of manganese deficiency and added cerium on nitrogen metabolism of maize.

    PubMed

    Gong, Xiaolan; Qu, Chunxiang; Liu, Chao; Hong, Mengmeng; Wang, Ling; Hong, Fashui

    2011-12-01

    Manganese is one of the essential microelements for plant growth, and cerium is a beneficial element for plant growth. However, whether manganese deficiency affects nitrogen metabolism of plants and cerium improves the nitrogen metabolism of plants by exposure to manganese-deficient media are still unclear. The main aim of the study was to determine the effects of manganese deficiency in nitrogen metabolism and the roles of cerium in the improvement of manganese-deficient effects in maize seedlings. Maize seedlings were cultivated in manganese present Meider's nutrient solution. They were subjected to manganese deficiency and to cerium chloride administered in the manganese-present and manganese-deficient media. Maize seedlings grown in the various media were measured for key enzyme activities involved in nitrogen metabolism, such as nitrate reductase, glutamate dehydrogenase, glutamine synthetase, and glutamic-oxaloace transaminase. We found that manganese deficiency restricted uptake and transport of NO(3)(-), inhibited activities of nitrogen-metabolism-related enzymes, such as nitrate reductase, glutamine synthetase, and glutamic-oxaloace transaminase, thus decreasing the synthesis of chlorophyll and soluble protein, and inhibited the growth of maize seedlings. Manganese deficiency promoted the activity of glutamate dehydrogenase and reduced the toxicity of excess ammonia to the plant, while added cerium relieved the damage to nitrogen metabolism caused by manganese deficiency in maize seedlings. However, cerium addition exerted positively to relieve the damage of nitrogen metabolism process in maize seedlings caused by exposure to manganese-deficient media.

  4. [Affective disorders: endocrine and metabolic comorbidities].

    PubMed

    Cermolacce, M; Belzeaux, R; Adida, M; Azorin, J-M

    2014-12-01

    Links between affective and endocrine-metabolic disorders are numerous and complex. In this review, we explore most frequent endocrine-metabolic comorbidities. On the one hand, these comorbidities imply numerous iatrogenic effects from antipsychotics (metabolic side-effects) or from lithium (endocrine side-effects). On the other hand, these comorbidities are also associated with affective disorders independently from medication. We will successively examine metabolic syndrome, glycemic disturbances, obesity and thyroid disorders among patients with affective disorders. Endocrinemetabolic comorbidities can be individually encountered, but can also be associated. Therefore, they substantially impact morbidity and mortality by increasing cardiovascular risk factors. Two distinct approaches give an account of processes involved in these comorbidities: common environmental factors (iatrogenic effects, lifestyle), and/or shared physiological vulnerabilities. In conclusion, we provide a synthesis of important results and recommendations related to endocrine-metabolic comorbidities in affective disorders : heavy influence on morbidity and mortality, undertreatment of somatic diseases, importance of endocrine and metabolic side effects from main mood stabilizers, impact from sex and age on the prevalence of comorbidities, influence from previous depressive episodes in bipolar disorders, and relevance of systematic screening for subclinical (biological) disturbances.

  5. Glycolate Metabolism Is Under Nitrogen Control in Chlorella1

    PubMed Central

    Beudeker, Rob F.; Tabita, F. Robert

    1984-01-01

    The utilization of nitrate and ammonia as nitrogen sources had different effects on the metabolism of glycolate in Cholorella sorokiniana. During photolithotrophic growth with nitrate as nitrogen source, glycolate was metabolized via the glycine-serine pathway. Ammonia, produced as a result of glycolate metabolism, was reassimilated by glutamine synthetase. Two isoforms of this enzyme were present at different relative abundance in C. sorokiniana wild type and in a mutant with an increased capacity for the metabolism of glycolate (strain OR). During photolithotrophic growth in the presence of ammonia as sole nitrogen source, several lines of evidence indicated that glycolate was metabolized to malate, pyruvate, tricarboxylic acid cycle intermediates and related amino acids in C. sorokiniana wild-type cells. Malate synthase was induced and glycine decarboxylase and serine-glyoxylate aminotransferase were repressed in cells grown with ammonia. An inverse correlation was observed between aminating NADPH-glutamate dehydrogenase and the in vivo glycine decarboxylation rate. PMID:16663657

  6. Nitrogen metabolism and seed composition as influenced by glyphosate application in glyphosate-resistant soybean.

    PubMed

    Bellaloui, Nacer; Zablotowicz, Robert M; Reddy, Krishna N; Abel, Craig A

    2008-04-23

    Previous research has demonstrated that glyphosate can affect nitrogen fixation or nitrogen assimilation in soybean. This 2-year field study investigated the effects of glyphosate application of 1.12 and 3.36 kg of ae ha(-1) on nitrogen metabolism and seed composition in glyphosate-resistant (GR) soybean. There was no effect of glyphosate application on nitrogen fixation as measured by acetylene reduction assay, soybean yield, or seed nitrogen content. However, there were significant effects of glyphosate application on nitrogen assimilation, as measured by in vivo nitrate reductase activity (NRA) in leaves, roots, and nodules, especially at high rate. Transiently lower leaf nitrogen or (15)N natural abundance in high glyphosate application soybean supports the inhibition of NRA. With the higher glyphosate application level protein was significantly higher (10.3%) in treated soybean compared to untreated soybean. Inversely, total oil and linolenic acid were lowest at the high glyphosate application rate, but oleic acid was greatest (22%) in treated soybean. These results suggest that nitrate assimilation in GR soybean was more affected than nitrogen fixation by glyphosate application and that glyphosate application may alter nitrogen and carbon metabolism.

  7. Regulation of Nitrogen Metabolism by GATA Zinc Finger Transcription Factors in Yarrowia lipolytica

    PubMed Central

    2017-01-01

    ABSTRACT Fungi accumulate lipids in a manner dependent on the quantity and quality of the nitrogen source on which they are growing. In the oleaginous yeast Yarrowia lipolytica, growth on a complex source of nitrogen enables rapid growth and limited accumulation of neutral lipids, while growth on a simple nitrogen source promotes lipid accumulation in large lipid droplets. Here we examined the roles of nitrogen catabolite repression and its regulation by GATA zinc finger transcription factors on lipid metabolism in Y. lipolytica. Deletion of the GATA transcription factor genes gzf3 and gzf2 resulted in nitrogen source-specific growth defects and greater accumulation of lipids when the cells were growing on a simple nitrogen source. Deletion of gzf1, which is most similar to activators of genes repressed by nitrogen catabolite repression in filamentous ascomycetes, did not affect growth on the nitrogen sources tested. We examined gene expression of wild-type and GATA transcription factor mutants on simple and complex nitrogen sources and found that expression of enzymes involved in malate metabolism, beta-oxidation, and ammonia utilization are strongly upregulated on a simple nitrogen source. Deletion of gzf3 results in overexpression of genes with GATAA sites in their promoters, suggesting that it acts as a repressor, while gzf2 is required for expression of ammonia utilization genes but does not grossly affect the transcription level of genes predicted to be controlled by nitrogen catabolite repression. Both GATA transcription factor mutants exhibit decreased expression of genes controlled by carbon catabolite repression via the repressor mig1, including genes for beta-oxidation, highlighting the complex interplay between regulation of carbon, nitrogen, and lipid metabolism. IMPORTANCE Nitrogen source is commonly used to control lipid production in industrial fungi. Here we identified regulators of nitrogen catabolite repression in the oleaginous yeast Y

  8. Environmental factors affecting rates of nitrogen cycling

    SciTech Connect

    Lipschultz, F.

    1984-01-01

    The nitrogen cycle in the eutrophic Delaware river was studied in late summer, 1983 using /sup 15/N tracer additions of NHG/sub 4//sup +/, NO/sub 2//sup -/, and NO/sub 3//sup -/. Rates for nine different transformations were calculated simultaneously with a least-squares minimization analysis. Light was found to stimulate ammonium uptake and to inhibit ammonium oxidation. Rates for nitrification, ammonium uptake by phytoplankton, and photosynthesis were integrated over 24 hours and river depth. High turbidity lifted the effect of light inhibition on nitrification and restricted phytoplankton uptake. Uptake of ammonium contributed over 95% of the inorganic nitrogen ration for phytoplankton, with dark uptake accounting for more than 50%. A mass-conservation, box model of river was used to calculate rate constants required to reproduce observed nutrient concentration changes. The calculated constants correlated well with the measured /sup 15/N and oxygen integrated rates. Water-column nitrification was the major loss term for NH/sub 4//sup +/, while water column regeneration was the primary source. Loss of oxidized nitrogen was insignificant. Oxygen consumption and air-water exchange far exceeded net photosynthetic oxygen production. Nitrification contributed less than 1% to the oxygen demand near Philadelphia but up to 25% further downstream. Production of NO and N/sub 2/O was measured under varying oxygen concentrations in batch cultures of the nitrifying bacteria Nitrosomonas europaea and Nitrosococcus oceanus. Production of both gases increased relative to nitrite production as oxygen levels decreased.

  9. Affective Disorders, Bone Metabolism, and Osteoporosis

    PubMed Central

    2013-01-01

    The nature of the relationship between affective disorders, bone mineral density (BMD), and bone metabolism is unresolved, although there is growing evidence that many medications used to treat affective disorders are associated with low BMD or alterations in neuroendocrine systems that influence bone turnover. The objective of this review is to describe the current evidence regarding the association of unipolar and bipolar depression with BMD and indicators of bone metabolism, and to explore potential mediating and confounding influences of those relationships. The majority of studies of unipolar depression and BMD indicate that depressive symptoms are associated with low BMD. In contrast, evidence regarding the relationship between bipolar depression and BMD is inconsistent. There is limited but suggestive evidence to support an association between affective disorders and some markers of bone turnover. Many medications used to treat affective disorders have effects on physiologic systems that influence bone metabolism, and these conditions are also associated with a range of health behaviors that can influence osteoporosis risk. Future research should focus on disentangling the pathways linking psychotropic medications and their clinical indications with BMD and fracture risk. PMID:23874147

  10. Mutation of AREA affects growth, sporulation, nitrogen regulation, and pathogenicity in Colletotrichum gloeosporioides.

    PubMed

    Bi, Fangcheng; Ment, Dana; Luria, Neta; Meng, Xiangchun; Prusky, Dov

    2017-02-01

    The GATA transcription factor AreA is a global nitrogen regulator that restricts the utilization of complex and poor nitrogen sources in the presence of good nitrogen sources in microorganisms. In this study, we report the biological function of an AreA homolog (the CgareA gene) in the fruit postharvest pathogen Colletotrichum gloeosporioides. Targeted gene deletion mutants of areA exhibited significant reductions in vegetative growth, increases in conidia production, and slight decreases in conidial germination rates. Quantitative RT-PCR (qRT-PCR) analysis revealed that the expression of AreA was highly induced under nitrogen-limiting conditions. Moreover, compared to wild-type and complemented strains, nitrogen metabolism-related genes were misregulated in ΔareA mutant strains. Pathogenicity assays indicated that the virulence of ΔareA mutant strains were affected by the nitrogen content, but not the carbon content, of fruit hosts. Taken together, our results indicate that CgareA plays a critical role in fungal development, conidia production, regulation of nitrogen metabolism and virulence in Colletotrichum gloeosporioides.

  11. [Nitrogen metabolism and its control mechanisms].

    PubMed

    Bergner, H

    1989-01-01

    N intake in the form of protein has neither got an upper nor a lower limit for agricultural working animals within a diet and there is no control mechanism for it. A high surplus of certain amino acids results in a reduction of feed intake. N excretion in faeces depends on 1) the excretion of N containing indigestible feedstuffs, 2) bacterial nitrogen synthesis in the large intestine and 3) the excretion of true endogenous N containing substances (digestion enzymes, intestinal epithelium, N containing endogenous secretion). There are no other control mechanisms for N excretion in faeces. N excretion in urine mainly comprises the nitrogen from the degeneration of amino acids and nucleic acids. The interrelations between urea, NH3, allantoin, creatine and creatinine, uric acid and hippuric acid depend on the species (monogastric or ruminants), on the nitrogen and N amount consumed and on the recycling ratio of the amino acids. The absolute amount of N excretion is not subject to any control mechanism, it depends on the intake of protein and NPN substances, the interim stages, however, which lead to the formation of excretory products, are intermediately controlled. The most important interim stage is protein biosynthesis, which is a fixed, intermediately controlled value in maintenance level. Under growth conditions only, the protein synthesis quota can exceed the protein degradation quota of the total organism (positive N balance). The control mechanisms of protein biosynthesis have, according to current knowledge, the following structure: Stimulation: 1) growth hormone (STH) stimulates protein synthesis by means of somatomedins; 2) hormones of the thyroid gland (T4 and T3) are controlled by the hormone stimulating the thyroid gland (TSH); 3) insulin. Inhibition: 1) somatostatin inhibits STH, TSH and insulin; 2) cortisol directly inhibits protein synthesis and stimulates protein degradation. The control mechanisms of protein turnover in addition to genetic coding

  12. [Effect of carcinogenic nitrogen-containing compounds on cell metabolism].

    PubMed

    Antropov, V I; Samoĭlov, V O; Slepian, É I

    2012-01-01

    The brown frog (Rana temporaria) skin cells respiration, calcium metabolism and glycolysis, the tree frog (Hyla arborea) skin cells respiration and calcium metabolism were studied under short-term (first hours) and long-term (first days) exposure to nitrogenous compounds [N-nitroso-N-methyl urea (NMU) and thiourea (TU)]. The first direct effect of nitrogenous compounds exposure was cell breathing inhibition occurring in Rana temporaria skin cells after 28 days of exposure, and in Hyla arborea skin cells after 8 days of exposure. These changes were precided by decrease of lactate dehydrogenase (LDH) activity in Rana temporaria skin cells starting 16 days after NMU and TU introduction. The increase of intracellular calcium level was noted in tree frog skin cells 4-8 days after NMU and TU introduction, in brown frogs skin cells this parameter was unchanged.

  13. Fermentation and Hydrogen Metabolism Affect Uranium Reduction by Clostridia

    SciTech Connect

    Gao, Weimin; Francis, Arokiasamy J.

    2013-01-01

    Previously, it has been shown that not only is uranium reduction under fermentation condition common among clostridia species, but also the strains differed in the extent of their capability and the pH of the culture significantly affected uranium(VI) reduction. In this study, using HPLC and GC techniques, metabolic properties of those clostridial strains active in uranium reduction under fermentation conditions have been characterized and their effects on capability variance of uranium reduction discussed. Then, the relationship between hydrogen metabolism and uranium reduction has been further explored and the important role played by hydrogenase in uranium(VI) and iron(III) reduction by clostridia demonstrated. When hydrogen was provided as the headspace gas, uranium(VI) reduction occurred in the presence of whole cells of clostridia. This is in contrast to that of nitrogen as the headspace gas. Without clostridia cells, hydrogen alone could not result in uranium(VI) reduction. In alignment with this observation, it was also found that either copper(II) addition or iron depletion in the medium could compromise uranium reduction by clostridia. In the end, a comprehensive model was proposed to explain uranium reduction by clostridia and its relationship to the overall metabolism especially hydrogen (H2) production.

  14. Fermentation and Hydrogen Metabolism Affect Uranium Reduction by Clostridia

    PubMed Central

    Gao, Weimin; Francis, Arokiasamy J.

    2013-01-01

    Previously, it has been shown that not only is uranium reduction under fermentation condition common among clostridia species, but also the strains differed in the extent of their capability and the pH of the culture significantly affected uranium(VI) reduction. In this study, using HPLC and GC techniques, metabolic properties of those clostridial strains active in uranium reduction under fermentation conditions have been characterized and their effects on capability variance of uranium reduction discussed. Then, the relationship between hydrogen metabolism and uranium reduction has been further explored and the important role played by hydrogenase in uranium(VI) and iron(III) reduction by clostridia demonstrated. When hydrogen was provided as the headspace gas, uranium(VI) reduction occurred in the presence of whole cells of clostridia. This is in contrast to that of nitrogen as the headspace gas. Without clostridia cells, hydrogen alone could not result in uranium(VI) reduction. In alignment with this observation, it was also found that either copper(II) addition or iron depletion in the medium could compromise uranium reduction by clostridia. In the end, a comprehensive model was proposed to explain uranium reduction by clostridia and its relationship to the overall metabolism especially hydrogen (H2) production. PMID:25937978

  15. Fermentation and Hydrogen Metabolism Affect Uranium Reduction by Clostridia

    DOE PAGES

    Gao, Weimin; Francis, Arokiasamy J.

    2013-01-01

    Previously, it has been shown that not only is uranium reduction under fermentation condition common among clostridia species, but also the strains differed in the extent of their capability and the pH of the culture significantly affected uranium(VI) reduction. In this study, using HPLC and GC techniques, metabolic properties of those clostridial strains active in uranium reduction under fermentation conditions have been characterized and their effects on capability variance of uranium reduction discussed. Then, the relationship between hydrogen metabolism and uranium reduction has been further explored and the important role played by hydrogenase in uranium(VI) and iron(III) reduction bymore » clostridia demonstrated. When hydrogen was provided as the headspace gas, uranium(VI) reduction occurred in the presence of whole cells of clostridia. This is in contrast to that of nitrogen as the headspace gas. Without clostridia cells, hydrogen alone could not result in uranium(VI) reduction. In alignment with this observation, it was also found that either copper(II) addition or iron depletion in the medium could compromise uranium reduction by clostridia. In the end, a comprehensive model was proposed to explain uranium reduction by clostridia and its relationship to the overall metabolism especially hydrogen (H 2 ) production.« less

  16. The concentration of ammonia regulates nitrogen metabolism in Saccharomyces cerevisiae.

    PubMed

    ter Schure, E G; Silljé, H H; Verkleij, A J; Boonstra, J; Verrips, C T

    1995-11-01

    Saccharomyces cerevisiae was grown in a continuous culture at a single dilution rate with input ammonia concentrations whose effects ranged from nitrogen limitation to nitrogen excess and glucose limitation. The rate of ammonia assimilation (in millimoles per gram of cells per hour) was approximately constant. Increased extracellular ammonia concentrations are correlated with increased intracellular glutamate and glutamine concentrations, increases in levels of NAD-dependent glutamate dehydrogenase activity and its mRNA (gene GDH2), and decreases in levels of NADPH-dependent glutamate dehydrogenase activity and its mRNA (gene GDH1), as well as decreases in the levels of mRNA for the amino acid permease-encoding genes GAP1 and PUT4. The governing factor of nitrogen metabolism might be the concentration of ammonia rather than its flux.

  17. Implications of nitrogen phloem loading for carbon metabolism and transport during Arabidopsis development.

    PubMed

    Santiago, James P; Tegeder, Mechthild

    2017-03-14

    Metabolite transport processes and primary metabolism are highly interconnected. This study examined the importance of source-to-sink nitrogen partitioning, and associated nitrogen metabolism, for carbon capture, transport and usage. Specifically, Arabidopsis aap8 (AMINO ACID PERMEASE 8) mutant lines were analyzed to resolve the consequences of reduced amino acid phloem loading for source leaf carbon metabolism, sucrose phloem transport and sink development during vegetative and reproductive growth phase. Results showed that decreased amino acid transport had a negative effect on sink development of aap8 lines throughout the life cycle leading to an overall decrease in plant biomass. During vegetative stage, photosynthesis and carbohydrate levels were decreased in aap8 leaves, while expression of carbon metabolism and transport genes, as well as sucrose phloem transport were not affected despite reduced sink strength. However, when aap8 plants transitioned to reproductive phase, carbon fixation and assimilation as well as sucrose partitioning to siliques were strongly decreased. Overall, this work demonstrates that phloem loading of nitrogen has varying implication for carbon fixation, assimilation and source-to-sink allocation depending on plant growth stage. It further suggests alterations in source-sink relationships, and regulation of carbon metabolism and transport by sink strength in a development-dependent manner.

  18. THE EFFECT OF NITROGEN MUSTARDS ON ENZYMES AND TISSUE METABOLISM

    PubMed Central

    Barron, E. S. Guzman; Bartlett, Grant R.; Miller, Zelma Baker; Meyer, Joe; Seegmiller, J. E.

    1948-01-01

    Nitrogen mustards at a concentration forty times the minimum lethal dose inhibited the respiration of all tissues studied but affected anaerobic glycolysis very little. The inhibiting effect increased with time. The respiration of lymphoid tissue was extremely sensitive to nitrogen mustard, as concentrations below the LD50 definitely inhibited the respiration of rabbit lymph nodes. In tissue slices nitrogen mustards inhibited the oxidation of pyruvate and of l-amino acids and the utilization of NH3. A number of synthesis reactions were also inhibited, such as the synthesis of carbohydrate, of creatine, and of urea. When added to growing seeds, nitrogen mustards inhibited their growth. In rats given lethal doses of nitrogen mustards there were found complete inhibition of choline oxidation and strong inhibition of pyruvate oxidation by the kidney and partial inhibition of urea synthesis by the liver. Inhibition of bone marrow respiration by nitrogen mustards was prevented by the addition of choline, and of dimethylaminoethanol plus methionine The possible mechanism of nitrogen mustard intoxication is discussed. PMID:18858641

  19. Microbial Succession and Nitrogen Cycling in Cultured Biofilms as Affected by the Inorganic Nitrogen Availability.

    PubMed

    Li, Shuangshuang; Peng, Chengrong; Wang, Chun; Zheng, Jiaoli; Hu, Yao; Li, Dunhai

    2017-01-01

    Biofilms play important roles in nutrients and energy cycling in aquatic ecosystems. We hypothesized that as eutrophication could change phytoplankton community and decrease phytoplankton diversity, ambient inorganic nitrogen level will affect the microbial community and diversity of biofilms and the roles of biofilms in nutrient cycling. Biofilms were cultured using a flow incubator either with replete inorganic nitrogen (N-rep) or without exogenous inorganic nitrogen supply (N-def). The results showed that the biomass and nitrogen and phosphorous accumulation of biofilms were limited by N deficiency; however, as expected, the N-def biofilms had significantly higher microbial diversity than that of N-rep biofilms. The microbial community of biofilms shifted in composition and abundance in response to ambient inorganic nitrogen level. For example, as compared between the N-def and the N-rep biofilms, the former consisted of more diazotrophs, while the latter consisted of more denitrifying bacteria. As a result of the shift of the functional microbial community, the N concentration of N-rep medium kept decreasing, while that of N-def medium showed an increasing trend in the late stage. This indicates that biofilms can serve as the source or the sink of nitrogen in aquatic ecosystems, and it depends on the inorganic nitrogen availability.

  20. Coupled effects of light and nitrogen source on the urea cycle and nitrogen metabolism over a diel cycle in the marine diatom Thalassiosira pseudonana.

    PubMed

    Bender, Sara J; Parker, Micaela S; Armbrust, E Virginia

    2012-03-01

    Diatoms are photoautotrophic organisms capable of growing on a variety of inorganic and organic nitrogen sources. Discovery of a complete urea cycle in diatoms was surprising, as this pathway commonly functions in heterotrophic organisms to rid cells of waste nitrogen. To determine how the urea cycle is integrated into cellular nitrogen metabolism and energy management, the centric diatom Thalassiosira pseudonana was maintained in semi-continuous batch cultures on nitrate, ammonium, or urea as the sole nitrogen source, under a 16: 8 light: dark cycle and at light intensities that were low, saturating, or high for growth. Steady-state transcript levels were determined for genes encoding enzymes linked to the urea cycle, urea hydrolysis, glutamine synthesis, pyrimidine synthesis, photorespiration, and energy storage. Transcript abundances were significantly affected by nitrogen source, light intensity and a diel cycle. The impact of N source on differential transcript accumulation was most apparent under the highest light intensity. Models of cellular metabolism under high light were developed based on changes in transcript abundance and predicted enzyme localizations. We hypothesize that the urea cycle is integrated into nitrogen metabolism through its connection to glutamine and in the eventual production of urea. These findings have important implications for nitrogen flow in the cell over diel cycles at surface ocean irradiances.

  1. Universal scaling of respiratory metabolism, size and nitrogen in plants.

    PubMed

    Reich, Peter B; Tjoelker, Mark G; Machado, Jose-Luis; Oleksyn, Jacek

    2006-01-26

    The scaling of respiratory metabolism to body size in animals is considered to be a fundamental law of nature, and there is substantial evidence for an approximate (3/4)-power relation. Studies suggest that plant respiratory metabolism also scales as the (3/4)-power of mass, and that higher plant and animal scaling follow similar rules owing to the predominance of fractal-like transport networks and associated allometric scaling. Here, however, using data obtained from about 500 laboratory and field-grown plants from 43 species and four experiments, we show that whole-plant respiration rate scales approximately isometrically (scaling exponent approximately 1) with total plant mass in individual experiments and has no common relation across all data. Moreover, consistent with theories about biochemically based physiological scaling, isometric scaling of whole-plant respiration rate to total nitrogen content is observed within and across all data sets, with a single relation common to all data. This isometric scaling is unaffected by growth conditions including variation in light, nitrogen availability, temperature and atmospheric CO2 concentration, and is similar within or among species or functional groups. These findings suggest that plants and animals follow different metabolic scaling relations, driven by distinct mechanisms.

  2. Diet and nitrogen metabolism during spaceflight on the shuttle.

    PubMed

    Stein, T P; Leskiw, M J; Schluter, M D

    1996-07-01

    Human spaceflight is associated with a loss of body protein. To investigate this problem, dietary intake, nitrogen balance, the whole body protein, and fibrinogen protein synthesis rates were measured on the crews of two Spacelab Life Sciences (SLS) shuttle missions before, during, and after spaceflight. The first mission, SLS-1, lasted 9.5 days, and the second, SLS-2, lasted 15 days. The 15N-glycine method was used for the protein synthesis measurements. The following results were obtained. 1) There was a rapid decline in weight for the first 5 days and then the body weight appeared to stabilize. 2) The mean energy intake preflight was 39.0 +/- 2.5 kcal x kg-1 x day-1 (n = 10). There was a sharp drop in dietary intake on flight day 1, with recovery by the second day, and then energy intake was constant at 30.4 +/- 1.5 kcal x kg-1 x day-1 (n = 12) for the remainder of the flight period (P < 0.05). 3) Nitrogen retention was decreased during flight, with the magnitude of the decrease lessening toward the end of the mission. The daily mean nitrogen balance changed from 58 +/- 9 mg x kg-1 x day-1 (n = 9) preflight to 16 +/- 3 mg N x kg-1 x day-1; P < 0.05; n = 11) in flight, corresponding to a loss of approximately 1 kg of lean body mass over 14 days. 4) Whole body protein synthesis was increased early in flight and on recovery, as was fibrinogen synthesis. We conclude that 1) the rapid readjustment and stabilization of energy intake and the improved nitrogen retention with increasing flight duration are consistent with a rapid metabolic accommodation to the novel environment; and that 2) the increased protein turnover indicates that a metabolic stress response is an important factor in this adjustment process.

  3. Nitrogen metabolism in Lignifying Pinus taeda cell cultures

    NASA Technical Reports Server (NTRS)

    van Heerden, P. S.; Towers, G. H.; Lewis, N. G.

    1996-01-01

    The primary metabolic fate of phyenylalanine, following its deamination in plants, is conscription of its carbon skeleton for lignin, suberin, flavonoid, and related metabolite formation. Since this accounts for approximately 30-40% of all organic carbon, an effective means of recycling the liberated ammonium ion must be operative. In order to establish how this occurs, the uptake and metabolism of various 15N-labeled precursors (15N-Phe, 15NH4Cl, 15N-Gln, and 15N-Glu) in lignifying Pinus taeda cell cultures was investigated, using a combination of high performance liquid chromatography, 15N NMR, and gas chromatograph-mass spectrometry analyses. It was found that the ammonium ion released during active phenylpropanoid metabolism was not made available for general amino acid/protein synthesis. Rather it was rapidly recycled back to regenerate phenylalanine, thereby providing an effective means of maintaining active phenylpropanoid metabolism with no additional nitrogen requirement. These results strongly suggest that, in lignifying cells, ammonium ion reassimilation is tightly compartmentalized.

  4. Factors affecting metabolic syndrome by lifestyle

    PubMed Central

    Ki, Nam-Kyun; Lee, Hae-Kag; Cho, Jae-Hwan; Kim, Seon-Chil; Kim, Nak-Sang

    2016-01-01

    [Purpose] The aim of this study was to explore lifestyle factors in relation to metabolic syndrome so as to be able to utilize the results as baseline data for the furtherance of health-care and medical treatment. [Subjects and Methods] This study was conducted with patients who visited a health care center located in Seoul and had abdominal ultrasonography between 2 March 2013 and 28 February, 2014. Heights, weights, and blood pressures were measured by automatic devices. Three radiologists examined the patients using abdominal ultrasonography for gallstone diagnosis. The statuses of patients with regard to smoking, alcohol, coffee, and physical activities were explored for the lifestyle investigation. For investigating baseline demographics, we first used descriptive statistics. We then used the χ2 test to analyze lifestyles and gallstone prevalence with regard to the presence of metabolic syndrome. Lastly, logistic regression analysis was conducted to discover the risk factors of metabolic syndrome. [Results] For men, body mass index, maximum gallstone size, and waist circumference were revealed as risk factors for metabolic syndrome, in descending order of the degree of risk. For females, gallstone presence was the most significant risk factor, followed by waist circumference. [Conclusion] Metabolic disease mainly presents itself along with obesity, and we should become more focused on preventing and treating this disease. A large-scale prospective study is needed in the future, as the cause of nonalcoholic steatohepatitis remained unclear in this study. PMID:26957725

  5. Carbon and nitrogen metabolism in ectomycorrhizal fungi and ectomycorrhizas.

    PubMed

    Martin, F; Ramstedt, M; Söderhäll, K

    1987-01-01

    The literature concerning the metabolism of carbon and nitrogen compounds in ectomycorrhizal associations of trees is reviewed. The absorption and translocation of mineral ions by the mycelia require an energy source and a reductant which are both supplied by respiratory catabolism of carbohydrates produced by the host plant. Photosynthates are also required to generate the carbon skeletons for amino acid and carbohydrate syntheses during the growth of the mycelia. Competition for photosynthates occurs between the fungal cells and the various vegetative sinks in the host tree. The nature of carbon compounds involved in these processes, their routes of metabolism, the mechanisms of control and the partitioning of metabolites between the various sites of utilization are only poorly understood. Both ascomycetous and basidiomycetous ectomycorrhizal fungi synthesize and some, if not all, accumulate mannitol, trehalose and triglycerides. The fungal strains employ the Embden--Meyerhof pathway of glucose catabolism and the key enzymes of the pentose phosphate pathway (6-phosphogluconate dehydrogenase, glucose-6-phosphate dehydrogenase, transaldolase and transketolase). Anaplerotic CO2 fixation, via pyruvate carboxylase and/or phosphoenolpyruvate carboxykinase, provides high pools of amino acids. This process could be important in the recapture and assimilation of respired CO2 in the rhizosphere. The ectomycorrhizas are thought to contain the Embden--Meyerhof pathway, the pentose phosphate pathway and the tricarboxylic acid cycle, which provide the carbon skeletons for the assimilation of ammonia into amino acids. The main route of assimilation of ammonia appears to be through the glutamine synthetase-glutamate synthase cycle in the ectomycorrhizas. Glutamate dehydrogenase plays a minor role in this process. Glutamate dehydrogenase and glutamine synthetase are present in free-living ectomycorrhizal fungi and they participate in the assimilation of ammonia and the synthesis

  6. Mapping genetic variants underlying differences in the central nitrogen metabolism in fermenter yeasts.

    PubMed

    Jara, Matías; Cubillos, Francisco A; García, Verónica; Salinas, Francisco; Aguilera, Omayra; Liti, Gianni; Martínez, Claudio

    2014-01-01

    Different populations within a species represent a rich reservoir of allelic variants, corresponding to an evolutionary signature of withstood environmental constraints. Saccharomyces cerevisiae strains are widely utilised in the fermentation of different kinds of alcoholic beverages, such as, wine and sake, each of them derived from must with distinct nutrient composition. Importantly, adequate nitrogen levels in the medium are essential for the fermentation process, however, a comprehensive understanding of the genetic variants determining variation in nitrogen consumption is lacking. Here, we assessed the genetic factors underlying variation in nitrogen consumption in a segregating population derived from a cross between two main fermenter yeasts, a Wine/European and a Sake isolate. By linkage analysis we identified 18 main effect QTLs for ammonium and amino acids sources. Interestingly, majority of QTLs were involved in more than a single trait, grouped based on amino acid structure and indicating high levels of pleiotropy across nitrogen sources, in agreement with the observed patterns of phenotypic co-variation. Accordingly, we performed reciprocal hemizygosity analysis validating an effect for three genes, GLT1, ASI1 and AGP1. Furthermore, we detected a widespread pleiotropic effect on these genes, with AGP1 affecting seven amino acids and nine in the case of GLT1 and ASI1. Based on sequence and comparative analysis, candidate causative mutations within these genes were also predicted. Altogether, the identification of these variants demonstrate how Sake and Wine/European genetic backgrounds differentially consume nitrogen sources, in part explaining independently evolved preferences for nitrogen assimilation and representing a niche of genetic diversity for the implementation of practical approaches towards more efficient strains for nitrogen metabolism.

  7. Mapping Genetic Variants Underlying Differences in the Central Nitrogen Metabolism in Fermenter Yeasts

    PubMed Central

    García, Verónica; Salinas, Francisco; Aguilera, Omayra; Liti, Gianni; Martínez, Claudio

    2014-01-01

    Different populations within a species represent a rich reservoir of allelic variants, corresponding to an evolutionary signature of withstood environmental constraints. Saccharomyces cerevisiae strains are widely utilised in the fermentation of different kinds of alcoholic beverages, such as, wine and sake, each of them derived from must with distinct nutrient composition. Importantly, adequate nitrogen levels in the medium are essential for the fermentation process, however, a comprehensive understanding of the genetic variants determining variation in nitrogen consumption is lacking. Here, we assessed the genetic factors underlying variation in nitrogen consumption in a segregating population derived from a cross between two main fermenter yeasts, a Wine/European and a Sake isolate. By linkage analysis we identified 18 main effect QTLs for ammonium and amino acids sources. Interestingly, majority of QTLs were involved in more than a single trait, grouped based on amino acid structure and indicating high levels of pleiotropy across nitrogen sources, in agreement with the observed patterns of phenotypic co-variation. Accordingly, we performed reciprocal hemizygosity analysis validating an effect for three genes, GLT1, ASI1 and AGP1. Furthermore, we detected a widespread pleiotropic effect on these genes, with AGP1 affecting seven amino acids and nine in the case of GLT1 and ASI1. Based on sequence and comparative analysis, candidate causative mutations within these genes were also predicted. Altogether, the identification of these variants demonstrate how Sake and Wine/European genetic backgrounds differentially consume nitrogen sources, in part explaining independently evolved preferences for nitrogen assimilation and representing a niche of genetic diversity for the implementation of practical approaches towards more efficient strains for nitrogen metabolism. PMID:24466135

  8. Nitrogen metabolism in tabtoxinine-. beta. -lactam-tolerant oats

    SciTech Connect

    Knight, T.J.; Langston-Unkefer, P.J. New Mexico State Univ. Plant Genetic Engineering Lab., Las Cruces ); Sengupta-Gopalan, C. )

    1989-04-01

    Infestation of the rhizosphere of oat plants with Pseudomonas syringae pv. tabaci results in rapid death of normal oats. This is a consequence of the action of the bacterially delivered inhibitor of glutamine synthetase, tabtoxinine-{beta}-lactam (T{beta}L). Such infested plants contain no active glutamine synthetase. We have screened for a small population of oats that contain leaf glutamine synthetases that are insensitive to T{beta}L and which have increased leaf GS activity. The root GS is inactive. We have examined these plants' altered nitrogen metabolism and further characterized their novel glutamine synthetase using both biochemical and molecular biological approaches. This investigation has revealed a GS with unusual electrophoretic mobility by native PAGE.

  9. Metabolism of Nitrogen Oxides in Ammonia-Oxidizing Bacteria

    NASA Astrophysics Data System (ADS)

    Kozlowski, J.; Stein, L. Y.

    2014-12-01

    Ammonia-oxidizing bacteria (AOB) are key microorganisms in the transformation of nitrogen intermediates in most all environments. Until recently there was very little work done to elucidate the physiology of ammonia-oxidizing bacteria cultivated from variable trophic state environments. With a greater variety of ammonia-oxidizers now in pure culture the importance of comparative physiological and genomic analysis is crucial. Nearly all known physiology of ammonia-oxidizing bacteria lies within the Nitrosomonas genus with Nitrosomonas europaea strain ATCC 19718 as the model. To more broadly characterize and understand the nature of obligate ammonia chemolithotrophy and the contribution of AOB to production of nitrogen oxides, Nitrosomonas spp. and Nitrosospira spp. isolated from variable trophic states and with sequenced genomes, were utilized. Instantaneous ammonia- and hydroxylamine-oxidation kinetics as a function of oxygen and substrate concentration were measured using an oxygen micro-sensor. The pathway intermediates nitric oxide and nitrous oxide were measured in real time using substrate-specific micro-sensors to elucidate whether production of these molecules is stoichiometric with rates of substrate oxidation. Genomic inventory was compared among the strains to identify specific pathways and modules to explain physiological differences in kinetic rates and production of N-oxide intermediates as a condition of their adaptation to different ammonium concentrations. This work provides knowledge of how nitrogen metabolism is differentially controlled in AOB that are adapted to different concentrations of ammonium. Overall, this work will provide further insight into the control of ammonia oxidizing chemolithotrophy across representatives of the Nitrosomonas and Nitrosospira genus, which can then be applied to examine additional genome-sequenced AOB isolates.

  10. Nitrogen recycling during phenylpropanoid metabolism in sweet potato tubers

    NASA Technical Reports Server (NTRS)

    Singh, S.; Lewis, N. G.; Towers, G. H.

    1998-01-01

    In the first step of the phenylpropanoid metabolic pathway, L-phenylalanine (L-Phe) is deaminated to form E-cinnamate, in a conversion catalyzed by phenylalanine ammonia-lyase (PAL; EC 4.3.1.5). The metabolic fate of the ammonium ion (NH4+) produced in this reaction was investigated in sweet potato (Ipomoea batatas) tuber discs. [15N]-Labeled substrates including L-Phe, in the presence or absence of specific enzyme inhibitors, were administered to sweet potato discs in light under aseptic conditions. 15N-Nuclear magnetic resonance spectroscopic analyses revealed that the 15NH4+ liberated during the PAL reaction is first incorporated into the amide nitrogen of L-glutamine (L-Gln) and then into L-glutamate (L-Glu). These results extend our previous observations in pine and potato that PAL-generated NH4+ is assimilated by the glutamine synthetase (GS; EC 6.3.1.2)/glutamate synthase (GOGAT; EC 1.4.1.13) pathway, with the NH4+ so formed ultimately being recycled back to L-Phe via L-Glu as aminoreceptor and donor.

  11. How inhibiting nitrification affects nitrogen cycle and reduces ...

    EPA Pesticide Factsheets

    We conducted a meta-analysis of 103 nitrification inhibitor (NI) studies, and evaluated how NI application affects crop productivity and other ecosystem services in agricultural systems. Our results showed that, compared to conventional fertilizer practice, applications of NI along with nitrogen (N) fertilizer increased crop nitrogen use efficiency, crop yield, and altered the pathways and the amount of N loss to environment. NI application increased ammonia emission, but reduced nitrate leaching and nitrous oxide emission, which led to a reduction of 12.9% of the total N loss. The cost and benefit analysis showed that the economic benefit of reducing N’s environmental impacts offset the cost of NI. NI application could bring additional revenue of $163.72 ha-1 for a maize farm. Taken together, our findings show that NI application may create a win-win scenario that increases agricultural output, while reducing the negative impact on the environment. Policies that encourage NI application would reduce N’s environmental impacts. A group from Chinese Academy of Sciences, US EPA-ORD and North Carolina examined the net environmental and economic effects of nitrification inhibitors to reduce nitrate leaching associated with farm fertilizers. They conducted a meta-analysis of studies examining nitrification inhibitors, and found that NI application increased ammonia emission, but reduced nitrate leaching and nitrous oxide emission, which led to a reduction of 12.9

  12. Processes Affecting Nitrogen Speciation in a Karst Aquifer

    NASA Astrophysics Data System (ADS)

    Mahler, B. J.; Musgrove, M.; Wong, C. I.

    2011-12-01

    Like many karst aquifers, the Barton Springs segment of the Edwards aquifer, in central Texas, is in an area undergoing rapid growth in population, and there is concern as to how increased amounts of wastewater might affect groundwater quality. We measured concentrations and estimated loads of nitrogen (N) species in recharge to and discharge from the Barton Springs segment of the Edwards aquifer, central Texas, to evaluate processes affecting the transport and fate of N species in groundwater. Water samples were collected during 17 months (November 2008-March 2010) from five streams that contribute about 85% of recharge to the aquifer segment and from Barton Springs, the principal point of discharge from the segment. The sampling period spanned a range of climatic conditions from exceptional drought to above-normal rainfall. Samples were analyzed for N species (organic N + ammonia, ammonia, nitrate + nitrite, nitrite); loads of organic N and nitrate were estimated with LOADEST, a regression-based model that uses a time series of streamflow and measured constituent concentrations to estimate constituent loads. Concentrations of organic nitrogen and dissolved oxygen were higher and concentrations of nitrate were lower in surface water than in spring discharge, consistent with conversion of organic nitrogen to nitrate and associated consumption of dissolved oxygen in the aquifer. During the period of the study, the estimated load of organic N in recharge from streams (average daily load [adl] of 39 kg/d) was about 10 times that in Barton Springs discharge (adl of 9.4 kg/d), whereas the estimated load of nitrate in recharge from streams (adl of 123 kg/d) was slightly less than that in Barton Springs discharge (adl of 148 kg/d). The total average N load in recharge from streams and discharge from Barton Springs was not significantly different (adl of 162 and 157 kg/d, respectively), indicating that surface-water recharge can account for all of the N in Barton Springs

  13. Nitrogen and hydrophosphate affects glycolipids composition in microalgae

    PubMed Central

    Wang, Xin; Shen, Zhouyuan; Miao, Xiaoling

    2016-01-01

    Glycolipids had received increasing attention because of their uses in various industries like cosmetics, pharmaceuticals, food and machinery manufacture. Microalgae were competitive organisms to accumulate metabolic substance. However, using microalgae to produce glycolipid was rare at present. In this study, glycolipid content of Chlorella pyrenoidosa and Synechococcus sp. under different nitrate and hydrophosphate levels were investigated. The highest glycolipid contents of 24.61% for C. pyrenoidosa and 15.37% for Synechococcus sp. were obtained at nitrate absence, which were 17.19% for C. pyrenoidosa and 10.99% for Synechococcus sp. at 0.01 and 0 g L−1 hydrophosphate, respectively. Glycolipid productivities of two microalgae could reach at more than 10.59 mg L−1 d−1. Nitrate absence induced at least 8.5% increase in MGDG, DGDG and SQDG, while hydrophosphate absence resulted in over 21.2% increase in DGDG and over 48.4% increase in SQDG and more than 22.2% decrease in MGDG in two microalgae. Simultaneous nitrate and hydrophosphate limitation could make further improvement of glycolipid accumulation, which was more than 25% for C. pyrenoidosa and 21% for Synechococcus sp. These results suggest that nitrogen and phosphorus limitation or starvation should be an efficient way to improve microalgal glycolipid accumulation. PMID:27440670

  14. Two novel herbicide candidates affect Arabidopsis thaliana growth by inhibiting nitrogen and phosphate absorption.

    PubMed

    Sun, Chongchong; Jin, Yujian; He, Haifeng; Wang, Wei; He, Hongwu; Fu, Zhengwei; Qian, Haifeng

    2015-09-01

    Both 2-[(2,4-dichlorophenoxy)acetoxy](methy)lmethyl-5,5-dimethyl-1,3,2-dioxaphosphinan-2-one (termed as IIa) and 2-[(4-chloro-2-methyl-phenoxy)-acetoxy](methyl)methyl-5,5-dimethyl-1,3,2-dioxaphosphinan-2-one (termed as IIr) are novel herbicide candidates that positively affect herbicidal activity via the introduction of a phosphorus-containing heterocyclic ring. This report investigated the mechanism of IIa and IIr on weed control in the model plant Arabidopsis thaliana at physiological, ultrastructural and molecular levels. IIa and IIr significantly inhibited the growth of A. thaliana and altered its root structure by inhibiting energy metabolism and lipid or protein biosynthesis. These compounds also significantly affected the absorption of nitrogen and phosphorus by down-regulating the transcripts of nitrate transporter-related genes, ammonium transporter-related genes and phosphorus transporter-related genes.

  15. Nitrogen Metabolism of Lemna minor. I. Growth, Nitrogen Sources and Amino Acid Inhibition 1

    PubMed Central

    Joy, K. W.

    1969-01-01

    Lemna minor grown in sterile culture on a minerals-sucrose medium can utilize as nitrogen source, in order of increasing growth rate: ammonia, nitrate, a mixture of glutamic and aspartic acids plus arginine, or a balanced mixture of amino acids (hydrolyzed casein). Maximum growth is found with nitrate plus hydrolyzed casein. Many synthetic mixtures of amino acids are unable to support growth. Many single amino acids are inhibitory, and when added (at 2 mm or less) to cultures, growing in the presence of nitrate, cause a decrease in growth rate or even death of the plants (e.g. with alanine, valine, methionine or leucine). Some of these inhibitory effects are also found when the amino acid is added to cultures growing on ammonia or hydrolyzed casein. Arginine was the only amino acid of those tested which gave a marked stimulation of growth when added to cultures growing with inorganic nitrogen. The rapid rate of growth, sterile nature of tissue, decreased biological variation of samples containing many plants and ability to utilize different culture media make this an attractive organism for studies on higher plant metabolism. PMID:5799046

  16. Biological soil crusts emit large amounts of NO and HONO affecting the nitrogen cycle in drylands

    NASA Astrophysics Data System (ADS)

    Tamm, Alexandra; Wu, Dianming; Ruckteschler, Nina; Rodríguez-Caballero, Emilio; Steinkamp, Jörg; Meusel, Hannah; Elbert, Wolfgang; Behrendt, Thomas; Sörgel, Matthias; Cheng, Yafang; Crutzen, Paul J.; Su, Hang; Pöschl, Ulrich; Weber, Bettina

    2016-04-01

    Dryland systems currently cover ˜40% of the world's land surface and are still expanding as a consequence of human impact and global change. In contrast to that, information on their role in global biochemical processes is limited, probably induced by the presumption that their sparse vegetation cover plays a negligible role in global balances. However, spaces between the sparse shrubs are not bare, but soils are mostly covered by biological soil crusts (biocrusts). These biocrust communities belong to the oldest life forms, resulting from an assembly between soil particles and cyanobacteria, lichens, bryophytes, and algae plus heterotrophic organisms in varying proportions. Depending on the dominating organism group, cyanobacteria-, lichen-, and bryophyte-dominated biocrusts are distinguished. Besides their ability to restrict soil erosion they fix atmospheric carbon and nitrogen, and by doing this they serve as a nutrient source in strongly depleted dryland ecosystems. In this study we show that a fraction of the nitrogen fixed by biocrusts is metabolized and subsequently returned to the atmosphere in the form of nitric oxide (NO) and nitrous acid (HONO). These gases affect the radical formation and oxidizing capacity within the troposphere, thus being of particular interest to atmospheric chemistry. Laboratory measurements using dynamic chamber systems showed that dark cyanobacteria-dominated crusts emitted the largest amounts of NO and HONO, being ˜20 times higher than trace gas fluxes of nearby bare soil. We showed that these nitrogen emissions have a biogenic origin, as emissions of formerly strongly emitting samples almost completely ceased after sterilization. By combining laboratory, field, and satellite measurement data we made a best estimate of global annual emissions amounting to ˜1.1 Tg of NO-N and ˜0.6 Tg of HONO-N from biocrusts. This sum of 1.7 Tg of reactive nitrogen emissions equals ˜20% of the soil release under natural vegetation according

  17. Influences of lead (II) chloride on the nitrogen metabolism of spinach.

    PubMed

    Wu, Xiao; Xiao, Wu; Liu, Chao; Chao, Liu; Qu, Chunxiang; Chunxiang, Qu; Huang, Hao; Hao, Huang; Liu, Xiaoqing; Xiaoqing, Liu; Chen, Liang; Liang, Chen; Su, Mingyu; Mingyu, Su; Hong, Fashui; Fashui, Hong

    2008-03-01

    Lead (Pb(2+)) is a well-known highly toxic element. The mechanisms of the Pb(2+) toxicity are not well understood for nitrogen metabolism of higher plants. In this paper, we studied the effects of various concentrations of PbCl(2) on the nitrogen metabolism of growing spinach. The experimental results showed that Pb(2+) treatments significantly decreased the nitrate nitrogen (NO(-)(3)-N) absorption and inhibited the activities of nitrate reductase, glutamate dehydrogenase, glutamine synthase, and glutamic-pyruvic transaminase of spinach, and inhibited the synthesis of organic nitrogen compounds such as protein and chlorophyll. However, Pb(2+) treatments increased the accumulation of ammonium nitrogen NH(+)(4)-N)in spinach cell. It implied that Pb(2+) could inhibit inorganic nitrogen to be translated into organic nitrogen in spinach, thus led to the reduction in spinach growth.

  18. Nitrogen metabolism in pepper plants applied with different bioregulators.

    PubMed

    Ruiz, J M; Castilla, N; Romero, L

    2000-07-01

    Certain bioregulators were studied in relation to nitrogen metabolism of pepper plants (Capsicum annuum L. cv. Lamuyo). Plants were grown under controlled conditions and submitted to regular fertilization with macro- and micronutrients. Treatments were as follows: nontreated control (T0); fosfonutren [essential amino acids and micronutrients (46.9 mg L(-)(1))] (T1); biozyme [GA(3) (32.2 mg L(-)(1)) plus IAA (32.2 mg L(-)(1)) plus zeatin (83.2 mg L(-)(1)) plus chelated micronutrients] (T2); and GA(3) [16 mg L(-)(1)] (T3). The concentrations of NO(3)(-), organic N, amino acids, and proteins, the activities of nitrate reductase (NR) and nitrite reductase (NiR), and finally the foliar dry weight and yield were analyzed. The results indicated that the application of certain bioregulators, such as fosfonutren (T1), which contain amino acids can cause a negative effect on the efficiency and utilization of NO(3)(-), resulting in a drastic loss in growth and yield, even under the control treatment, in which no bioregulator was applied. On the contrary, the application of certain bioregulators based principally on the combination of different hormones, as in the case of biozyme (T2), increased NO(3)(-) assimilation under our experimental conditions, due possibly to a greater availability of these bioregulators in the leaves and increased NR and NiR activities. This appears to explain why the T2 treatment gave the greatest foliar dry weight and fruit yield per plant in the experiment.

  19. Nitrogen metabolism in plants under low oxygen stress.

    PubMed

    Limami, Anis M; Diab, Houssein; Lothier, Jérémy

    2014-03-01

    More frequent flooding and waterlogging events due to more heavy precipitation are expected worldwide in the context of climate change. Accordingly, adaptation of plants to oxygen limitation at both cellular and whole plant levels should be investigated thoroughly, that derived knowledge could be taken into account in breeding programs and agronomical practices for saving plant fitness, growth and development even when oxygen availability is low. In the present review, we highlight current knowledge on essential aspects of low oxygen stress-induced changes in nitrogen metabolism. The involvement of two possible pathways for NO production either via the reaction catalyzed by nitrate reductase or at Complex III or IV of the mitochondrial electron transport chain, thus contributing to ATP synthesis via the so-called nitrite-NO respiration, is discussed. NO is proposed to be scavenged by non-symbiotic hemoglobin (Hb) in a Hb/NO cycle, in which NAD(P)H is oxidized for the conversion of NO into NO3(-). The investigation of an additional adaptation to the decrease in oxygen availability via transcriptional and posttranslational regulation of amino acid synthesis pathways, using publicly available transcriptome and translatome data for Arabidopsis thaliana and rice is also discussed.

  20. Leucine metabolism regulates TRI6 expression and affects deoxynivalenol production and virulence in Fusarium graminearum.

    PubMed

    Subramaniam, Rajagopal; Narayanan, Swara; Walkowiak, Sean; Wang, Li; Joshi, Manisha; Rocheleau, Hélène; Ouellet, Thérèse; Harris, Linda J

    2015-11-01

    TRI6 is a positive regulator of the trichothecene gene cluster and the production of trichothecene mycotoxins [deoxynivalenol (DON)] and acetylated forms such as 15-Acetyl-DON) in the cereal pathogen Fusarium graminearum. As a global transcriptional regulator, TRI6 expression is modulated by nitrogen-limiting conditions, sources of nitrogen and carbon, pH and light. However, the mechanism by which these diverse environmental factors affect TRI6 expression remains underexplored. In our effort to understand how nutrients affect TRI6 regulation, comparative digital expression profiling was performed with a wild-type F. graminearum and a Δtri6 mutant strain, grown in nutrient-rich conditions. Analysis showed that TRI6 negatively regulates genes of the branched-chain amino acid (BCAA) metabolic pathway. Feeding studies with deletion mutants of MCC, encoding methylcrotonyl-CoA-carboxylase, one of the key enzymes of leucine metabolism, showed that addition of leucine specifically down-regulated TRI6 expression and reduced 15-ADON accumulation. Constitutive expression of TRI6 in the Δmcc mutant strain restored 15-ADON production. A combination of cellophane breach assays and pathogenicity experiments on wheat demonstrated that disrupting the leucine metabolic pathway significantly reduced disease. These findings suggest a complex interaction between one of the primary metabolic pathways with a global regulator of mycotoxin biosynthesis and virulence in F. graminearum.

  1. 40 CFR Table 2 to Subpart Fff of... - Nitrogen Oxides Requirements for Affected Facilities

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 8 2010-07-01 2010-07-01 false Nitrogen Oxides Requirements for... Before September 20, 1994 Pt. 62, Subpt. FFF, Table 2 Table 2 to Subpart FFF of Part 62—Nitrogen Oxides Requirements for Affected Facilities Municipal waste combustor technology Nitrogen oxides emission limit...

  2. 40 CFR Table 2 to Subpart Fff of... - Nitrogen Oxides Requirements for Affected Facilities

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 9 2013-07-01 2013-07-01 false Nitrogen Oxides Requirements for... Before September 20, 1994 Pt. 62, Subpt. FFF, Table 2 Table 2 to Subpart FFF of Part 62—Nitrogen Oxides Requirements for Affected Facilities Municipal waste combustor technology Nitrogen oxides emission limit...

  3. 40 CFR Table 2 to Subpart Fff of... - Nitrogen Oxides Requirements for Affected Facilities

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 9 2012-07-01 2012-07-01 false Nitrogen Oxides Requirements for... Before September 20, 1994 Pt. 62, Subpt. FFF, Table 2 Table 2 to Subpart FFF of Part 62—Nitrogen Oxides Requirements for Affected Facilities Municipal waste combustor technology Nitrogen oxides emission limit...

  4. 40 CFR Table 2 to Subpart Fff of... - Nitrogen Oxides Requirements for Affected Facilities

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 9 2014-07-01 2014-07-01 false Nitrogen Oxides Requirements for... Before September 20, 1994 Pt. 62, Subpt. FFF, Table 2 Table 2 to Subpart FFF of Part 62—Nitrogen Oxides Requirements for Affected Facilities Municipal waste combustor technology Nitrogen oxides emission limit...

  5. 40 CFR Table 2 to Subpart Fff of... - Nitrogen Oxides Requirements for Affected Facilities

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 8 2011-07-01 2011-07-01 false Nitrogen Oxides Requirements for... Before September 20, 1994 Pt. 62, Subpt. FFF, Table 2 Table 2 to Subpart FFF of Part 62—Nitrogen Oxides Requirements for Affected Facilities Municipal waste combustor technology Nitrogen oxides emission limit...

  6. Deciphering the role of aspartate and prephenate aminotransferase activities in plastid nitrogen metabolism.

    PubMed

    de la Torre, Fernando; El-Azaz, Jorge; Avila, Concepción; Cánovas, Francisco M

    2014-01-01

    Chloroplasts and plastids of nonphotosynthetic plant cells contain two aspartate (Asp) aminotransferases: a eukaryotic type (Asp5) and a prokaryotic-type bifunctional enzyme displaying Asp and prephenate aminotransferase activities (PAT). We have identified the entire Asp aminotransferase gene family in Nicotiana benthamiana and isolated and cloned the genes encoding the isoenzymes with plastidic localization: NbAsp5 and NbPAT. Using a virus-induced gene silencing approach, we obtained N. benthamiana plants silenced for NbAsp5 and/or NbPAT. Phenotypic and metabolic analyses were conducted in silenced plants to investigate the specific roles of these enzymes in the biosynthesis of essential amino acids within the plastid. The NbAsp5 silenced plants had no changes in phenotype, exhibiting similar levels of free Asp and glutamate as control plants, but contained diminished levels of asparagine and much higher levels of lysine. In contrast, the suppression of NbPAT led to a severe reduction in growth and strong chlorosis symptoms. NbPAT silenced plants exhibited extremely reduced levels of asparagine and were greatly affected in their phenylalanine metabolism and lignin deposition. Furthermore, NbPAT suppression triggered a transcriptional reprogramming in plastid nitrogen metabolism. Taken together, our results indicate that NbPAT has an overlapping role with NbAsp5 in the biosynthesis of Asp and a key role in the production of phenylalanine for the biosynthesis of phenylpropanoids. The analysis of NbAsp5/NbPAT cosilenced plants highlights the central role of both plastidic aminotransferases in nitrogen metabolism; however, only NbPAT is essential for plant growth and development.

  7. Oral MSG administration alters hepatic expression of genes for lipid and nitrogen metabolism in suckling piglets.

    PubMed

    Chen, Gang; Zhang, Jun; Zhang, Yuzhe; Liao, Peng; Li, Tiejun; Chen, Lixiang; Yin, Yulong; Wang, Jinquan; Wu, Guoyao

    2014-01-01

    This experiment was conducted to investigate the effects of oral administration of monosodium glutamate (MSG) on expression of genes for hepatic lipid and nitrogen metabolism in piglets. A total of 24 newborn pigs were assigned randomly into one of four treatments (n = 6/group). The doses of oral MSG administration, given at 8:00 and 18:00 to sow-reared piglets between 0 and 21 days of age, were 0 (control), 0.06 (low dose), 0.5 (intermediate dose), and 1 (high dose) g/kg body weight/day. At the end of the 3-week treatment, serum concentrations of total protein and high-density lipoprotein cholesterol in the intermediate dose group were elevated than those in the control group (P < 0.05). Hepatic mRNA levels for fatty acid synthase, acetyl-coA carboxylase, insulin-like growth factor-1, glutamate-oxaloacetate transaminase, and glutamate-pyruvate transaminase were higher in the middle-dose group (P < 0.05), compared with the control group. MSG administration did not affect hepatic mRNA levels for hormone-sensitive lipase or carnitine palmitoyl transferase-1. We conclude that oral MSG administration alters hepatic expression of certain genes for lipid and nitrogen metabolism in suckling piglets.

  8. Effect of ammonia stress on nitrogen metabolism of Ceratophyllum demersum.

    PubMed

    Gao, Jingqing; Li, Linshuai; Hu, Zhiyuan; Yue, Hui; Zhang, Ruiqin; Xiong, Zhiting

    2016-01-01

    The objective of the present study was to determine the effect of total ammonia N concentration and pH on N metabolism of Ceratophyllum demersum and to evaluate stress as a result of inorganic N enrichment in the water column on submerged macrophytes. Carefully controlled pH values distinguished between the effects of un-ionized NH3 and ionized NH4(+). The results showed that the most obvious consequence of ammonia addition was an overall increase in ammonia content and decrease in nitrate content in all tissues of fertilized plants. The activities of nitrate reductase and glutamine synthetase were inhibited by long-term ammonia addition. At the same time, ammonia addition significantly decreased soluble protein content and increased free amino acid content in all treatments. Another clear effect of ammonia addition was a decrease in carbon reserves. Therefore, the authors concluded that increased ammonia availability could affect plant survival and lead to a decline in C. demersum proliferation through a decrease in their carbon reserves. This interaction between N and C metabolism helps to explain changes in benthic vegetation as a result of steadily increasing coastal water eutrophication.

  9. Nitrogen Addition Significantly Affects Forest Litter Decomposition under High Levels of Ambient Nitrogen Deposition

    PubMed Central

    Chen, Gang; Peng, Yong; Xiao, Yin-long; Hu, Ting-xing; Zhang, Jian; Li, Xian-wei; Liu, Li; Tang, Yi

    2014-01-01

    Background Forest litter decomposition is a major component of the global carbon (C) budget, and is greatly affected by the atmospheric nitrogen (N) deposition observed globally. However, the effects of N addition on forest litter decomposition, in ecosystems receiving increasingly higher levels of ambient N deposition, are poorly understood. Methodology/Principal Findings We conducted a two-year field experiment in five forests along the western edge of the Sichuan Basin in China, where atmospheric N deposition was up to 82–114 kg N ha–1 in the study sites. Four levels of N treatments were applied: (1) control (no N added), (2) low-N (50 kg N ha–1 year–1), (3) medium-N (150 kg N ha–1 year–1), and (4) high-N (300 kg N ha–1 year–1), N additions ranging from 40% to 370% of ambient N deposition. The decomposition processes of ten types of forest litters were then studied. Nitrogen additions significantly decreased the decomposition rates of six types of forest litters. N additions decreased forest litter decomposition, and the mass of residual litter was closely correlated to residual lignin during the decomposition process over the study period. The inhibitory effect of N addition on litter decomposition can be primarily explained by the inhibition of lignin decomposition by exogenous inorganic N. The overall decomposition rate of ten investigated substrates exhibited a significant negative linear relationship with initial tissue C/N and lignin/N, and significant positive relationships with initial tissue K and N concentrations; these relationships exhibited linear and logarithmic curves, respectively. Conclusions/Significance This study suggests that the expected progressive increases in N deposition may have a potential important impact on forest litter decomposition in the study area in the presence of high levels of ambient N deposition. PMID:24551152

  10. A Network Flow Analysis of the Nitrogen Metabolism in Beijing, China.

    PubMed

    Zhang, Yan; Lu, Hanjing; Fath, Brian D; Zheng, Hongmei; Sun, Xiaoxi; Li, Yanxian

    2016-08-16

    Rapid urbanization results in high nitrogen flows and subsequent environmental consequences. In this study, we identified the main metabolic components (nitrogen inputs, flows, and outputs) and used ecological network analysis to track the direct and integral (direct + indirect) metabolic flows of nitrogen in Beijing, China, from 1996 to 2012 and to quantify the structure of Beijing's nitrogen metabolic processes. We found that Beijing's input of new reactive nitrogen (Q, which represents nitrogen obtained from the atmosphere or nitrogen-containing materials used in production and consumption to support human activities) increased from 431 Gg in 1996 to 507 Gg in 2012. Flows to the industry, atmosphere, and household, and components of the system were clearly largest, with total integrated inputs plus outputs from these nodes accounting for 31, 29, and 15%, respectively, of the total integral flows for all paths. The flows through the sewage treatment and transportation components showed marked growth, with total integrated inputs plus outputs increasing to 3.7 and 5.2 times their 1996 values, respectively. Our results can help policymakers to locate the key nodes and pathways in an urban nitrogen metabolic system so they can monitor and manage these components of the system.

  11. Niche differentiation in nitrogen metabolism among methanotrophs within an operational taxonomic unit

    PubMed Central

    2014-01-01

    Background The currently accepted thesis on nitrogenous fertilizer additions on methane oxidation activity assumes niche partitioning among methanotrophic species, with activity responses to changes in nitrogen content being dependent on the in situ methanotrophic community structure Unfortunately, widely applied tools for microbial community assessment only have a limited phylogenetic resolution mostly restricted to genus level diversity, and not to species level as often mistakenly assumed. As a consequence, intragenus or intraspecies metabolic versatility in nitrogen metabolism was never evaluated nor considered among methanotrophic bacteria as a source of differential responses of methane oxidation to nitrogen amendments. Results We demonstrated that fourteen genotypically different Methylomonas strains, thus distinct below the level at which most techniques assign operational taxonomic units (OTU), show a versatile physiology in their nitrogen metabolism. Differential responses, even among strains with identical 16S rRNA or pmoA gene sequences, were observed for production of nitrite and nitrous oxide from nitrate or ammonium, nitrogen fixation and tolerance to high levels of ammonium, nitrate, and hydroxylamine. Overall, reduction of nitrate to nitrite, nitrogen fixation, higher tolerance to ammonium than nitrate and tolerance and assimilation of nitrite were general features. Conclusions Differential responses among closely related methanotrophic strains to overcome inhibition and toxicity from high nitrogen loads and assimilation of various nitrogen sources yield competitive fitness advantages to individual methane-oxidizing bacteria. Our observations proved that community structure at the deepest phylogenetic resolution potentially influences in situ functioning. PMID:24708438

  12. Dissolved Organic Nitrogen Inputs from Wastewater Treatment Plant Effluents Increase Responses of Planktonic Metabolic Rates to Warming.

    PubMed

    Vaquer-Sunyer, Raquel; Conley, Daniel J; Muthusamy, Saraladevi; Lindh, Markus V; Pinhassi, Jarone; Kritzberg, Emma S

    2015-10-06

    Increased anthropogenic pressures on coastal marine ecosystems in the last century are threatening their biodiversity and functioning. Global warming and increases in nutrient loadings are two major stressors affecting these systems. Global warming is expected to increase both atmospheric and water temperatures and increase precipitation and terrestrial runoff, further increasing organic matter and nutrient inputs to coastal areas. Dissolved organic nitrogen (DON) concentrations frequently exceed those of dissolved inorganic nitrogen in aquatic systems. Many components of the DON pool have been shown to supply nitrogen nutrition to phytoplankton and bacteria. Predictions of how global warming and eutrophication will affect metabolic rates and dissolved oxygen dynamics in the future are needed to elucidate their impacts on biodiversity and ecosystem functioning. Here, we experimentally determine the effects of simultaneous DON additions and warming on planktonic community metabolism in the Baltic Sea, the largest coastal area suffering from eutrophication-driven hypoxia. Both bacterioplankton community composition and metabolic rates changed in relation to temperature. DON additions from wastewater treatment plant effluents significantly increased the activation energies for community respiration and gross primary production. Activation energies for community respiration were higher than those for gross primary production. Results support the prediction that warming of the Baltic Sea will enhance planktonic respiration rates faster than it will for planktonic primary production. Higher increases in respiration rates than in production may lead to the depletion of the oxygen pool, further aggravating hypoxia in the Baltic Sea.

  13. Glycemic index of starch affects nitrogen retention in grower pigs.

    PubMed

    Drew, M D; Schafer, T C; Zijlstra, R T

    2012-04-01

    Three studies were performed to examine the effect of starch and protein digestion rates on N retention in grower pigs. In Exp. 1, the glycemic index (GI) of corn, a malting barley, and a slow-rumen-degradable barley (SRD-barley) were measured using 6 barrows (BW = 18.0 ± 0.5 kg). The GI of malting barley was greater (P < 0.05) than that of SRD-barley (71.1 vs. 49.4), and the GI of both barley cultivars was less (P < 0.05) than that of corn (104.8). In Exp. 2, the standardized ileal digestibility of AA and DE content of the 3 ingredients were determined using 5 ileal-cannulated barrows (BW = 20.7 ± 2.3). The apparent total-tract energy digestibility values of corn (86.1%) and malting barley (85.7%) were greater (P < 0.05) than that of SRD-barley (82.3%). The standardized ileal digestibility of Lys was 94.0, 92.6, and 92.4% for corn, malting barley, and SRD-barley, respectively, and did not differ among grains. In Exp. 3, 6 diets were formulated to equal DE (3.40 Mcal/kg), standardized ileal digestibility of Lys (8.6 g/kg), starch (424.9 g/kg), and digestible CP (180.0 g/kg) using the values obtained in Exp. 2. Three GI [high (corn), medium (malting barley), and low (SRD-barley)] and 2 rates of protein digestion [rapid (soy protein hydrolysate) and slow (soy protein isolate)] were tested in a 3 × 2 factorial arrangement with 36 barrows (BW = 32.2 ± 2.5 kg). Pigs were fed 3.0 times the maintenance energy requirement daily in 2 meals for 2 wk and were housed in metabolic crates to collect feces and urine separately. At the end of the study, intestinal contents were collected from 4 equal-length segments of the small intestine. The percentage of unabsorbed CP in segment 1 relative to dietary CP was greater (P < 0.05) for the soy protein isolate diet than for the soy protein hydrolysate diet (170.3 vs. 116.5%). The percentages of unabsorbed starch in segments 1 and 2 were greater (P < 0.05) for the SRD-barley diet than for the malting barley or corn diet. Nitrogen

  14. Deciphering the metabolic response of M ycobacterium tuberculosis to nitrogen stress

    PubMed Central

    Williams, Kerstin J.; Jenkins, Victoria A.; Barton, Geraint R.; Bryant, William A.; Krishnan, Nitya

    2015-01-01

    Summary A key component to the success of M ycobacterium tuberculosis as a pathogen is the ability to sense and adapt metabolically to the diverse range of conditions encountered in vivo, such as oxygen tension, environmental pH and nutrient availability. Although nitrogen is an essential nutrient for every organism, little is known about the genes and pathways responsible for nitrogen assimilation in M . tuberculosis. In this study we have used transcriptomics and chromatin immunoprecipitation and high‐throughput sequencing to address this. In response to nitrogen starvation, a total of 185 genes were significantly differentially expressed (96 up‐regulated and 89 down regulated; 5% genome) highlighting several significant areas of metabolic change during nitrogen limitation such as nitrate/nitrite metabolism, aspartate metabolism and changes in cell wall biosynthesis. We identify GlnR as a regulator involved in the nitrogen response, controlling the expression of at least 33 genes in response to nitrogen limitation. We identify a consensus GlnR binding site and relate its location to known transcriptional start sites. We also show that the GlnR response regulator plays a very different role in M . tuberculosis to that in non‐pathogenic mycobacteria, controlling genes involved in nitric oxide detoxification and intracellular survival instead of genes involved in nitrogen scavenging. PMID:26077160

  15. How inhibiting nitrification affects nitrogen cycle and reduces environmental impacts of anthropogenic nitrogen input.

    PubMed

    Qiao, Chunlian; Liu, Lingli; Hu, Shuijin; Compton, Jana E; Greaver, Tara L; Li, Quanlin

    2015-03-01

    Anthropogenic activities, and in particular the use of synthetic nitrogen (N) fertilizer, have doubled global annual reactive N inputs in the past 50-100 years, causing deleterious effects on the environment through increased N leaching and nitrous oxide (N2 O) and ammonia (NH3 ) emissions. Leaching and gaseous losses of N are greatly controlled by the net rate of microbial nitrification. Extensive experiments have been conducted to develop ways to inhibit this process through use of nitrification inhibitors (NI) in combination with fertilizers. Yet, no study has comprehensively assessed how inhibiting nitrification affects both hydrologic and gaseous losses of N and plant nitrogen use efficiency. We synthesized the results of 62 NI field studies and evaluated how NI application altered N cycle and ecosystem services in N-enriched systems. Our results showed that inhibiting nitrification by NI application increased NH3 emission (mean: 20%, 95% confidential interval: 33-67%), but reduced dissolved inorganic N leaching (-48%, -56% to -38%), N2 O emission (-44%, -48% to -39%) and NO emission (-24%, -38% to -8%). This amounted to a net reduction of 16.5% in the total N release to the environment. Inhibiting nitrification also increased plant N recovery (58%, 34-93%) and productivity of grain (9%, 6-13%), straw (15%, 12-18%), vegetable (5%, 0-10%) and pasture hay (14%, 8-20%). The cost and benefit analysis showed that the economic benefit of reducing N's environmental impacts offsets the cost of NI application. Applying NI along with N fertilizer could bring additional revenues of $163 ha(-1)  yr(-1) for a maize farm, equivalent to 8.95% increase in revenues. Our findings showed that NIs could create a win-win scenario that reduces the negative impact of N leaching and greenhouse gas production, while increases the agricultural output. However, NI's potential negative impacts, such as increase in NH3 emission and the risk of NI contamination, should be fully

  16. Abnormal folate metabolism in foetuses affected by neural tube defects.

    PubMed

    Dunlevy, Louisa P E; Chitty, Lyn S; Burren, Katie A; Doudney, Kit; Stojilkovic-Mikic, Taita; Stanier, Philip; Scott, Rosemary; Copp, Andrew J; Greene, Nicholas D E

    2007-04-01

    Folic acid supplementation can prevent many cases of neural tube defects (NTDs), whereas suboptimal maternal folate status is a risk factor, suggesting that folate metabolism is a key determinant of susceptibility to NTDs. Despite extensive genetic analysis of folate cycle enzymes, and quantification of metabolites in maternal blood, neither the protective mechanism nor the relationship between maternal folate status and susceptibility are understood in most cases. In order to investigate potential abnormalities in folate metabolism in the embryo itself, we derived primary fibroblastic cell lines from foetuses affected by NTDs and subjected them to the dU suppression test, a sensitive metabolic test of folate metabolism. Significantly, a subset of NTD cases exhibited low scores in this test, indicative of abnormalities in folate cycling that may be causally linked to the defect. Susceptibility to NTDs may be increased by suppression of the methylation cycle, which is interlinked with the folate cycle. However, reduced efficacy in the dU suppression test was not associated with altered abundance of the methylation cycle intermediates, s-adenosylmethionine and s-adenosylhomocysteine, suggesting that a methylation cycle defect is unlikely to be responsible for the observed abnormality of folate metabolism. Genotyping of samples for known polymorphisms in genes encoding folate-associated enzymes did not reveal any correlation between specific genotypes and the observed abnormalities in folate metabolism. These data suggest that as yet unrecognized genetic variants result in embryonic abnormalities of folate cycling that may be causally related to NTDs.

  17. Computational modeling to predict nitrogen balance during acute metabolic decompensation in patients with urea cycle disorders.

    PubMed

    MacLeod, Erin L; Hall, Kevin D; McGuire, Peter J

    2016-01-01

    Nutritional management of acute metabolic decompensation in amino acid inborn errors of metabolism (AA IEM) aims to restore nitrogen balance. While nutritional recommendations have been published, they have never been rigorously evaluated. Furthermore, despite these recommendations, there is a wide variation in the nutritional strategies employed amongst providers, particularly regarding the inclusion of parenteral lipids for protein-free caloric support. Since randomized clinical trials during acute metabolic decompensation are difficult and potentially dangerous, mathematical modeling of metabolism can serve as a surrogate for the preclinical evaluation of nutritional interventions aimed at restoring nitrogen balance during acute decompensation in AA IEM. A validated computational model of human macronutrient metabolism was adapted to predict nitrogen balance in response to various nutritional interventions in a simulated patient with a urea cycle disorder (UCD) during acute metabolic decompensation due to dietary non-adherence or infection. The nutritional interventions were constructed from published recommendations as well as clinical anecdotes. Overall, dextrose alone (DEX) was predicted to be better at restoring nitrogen balance and limiting nitrogen excretion during dietary non-adherence and infection scenarios, suggesting that the published recommended nutritional strategy involving dextrose and parenteral lipids (ISO) may be suboptimal. The implications for patients with AA IEM are that the medical course during acute metabolic decompensation may be influenced by the choice of protein-free caloric support. These results are also applicable to intensive care patients undergoing catabolism (postoperative phase or sepsis), where parenteral nutritional support aimed at restoring nitrogen balance may be more tailored regarding metabolic fuel selection.

  18. Nitrogen dioxide assimilation as affected by light level

    SciTech Connect

    Srivastava, H. ); Ormond, D.; Marie, B. )

    1989-04-01

    The air pollutant NO{sub 2} is absorbed and assimilated by plants to serve as a source of nitrogen but only to a limited extent. The objective of this research was to identify the constraints on NO{sub 2} assimilation. Differential light levels were used to manipulate carbohydrate metabolites available for nitrogen assimilation. Bean plants were grown at four light levels with or without nutrient nitrate and exposed to 0.25 ppm NO{sub 2} for 6h each day. Growth of roots and shoots was inhibited by NO{sub 2} in both the presence and absence of nutrient nitrate. The inhibition was most pronounced at the lowest light level. Light level similarly influenced the effect of nitrate and of NO{sub 2} on soluble protein, nitrate nitrogen and Kjeldahl nitrogen in the root and shoot tissues. Two experiments demonstrated that the injurious effects of NO{sub 2} are more pronounced at low light than at high light and that more NO{sub 2} is assimilated into soluble shoot protein at higher light levels.

  19. Low vapour pressure deficit affects nitrogen nutrition and foliar metabolites in silver birch

    PubMed Central

    Lihavainen, Jenna; Ahonen, Viivi; Keski-Saari, Sarita; Kontunen-Soppela, Sari; Oksanen, Elina; Keinänen, Markku

    2016-01-01

    Air humidity indicated as vapour pressure deficit (VPD) is directly related to transpiration and stomatal function of plants. We studied the effects of VPD and nitrogen (N) supply on leaf metabolites, plant growth, and mineral nutrition with young micropropagated silver birches (Betula pendula Roth.) in a growth chamber experiment. Plants that were grown under low VPD for 26 d had higher biomass, larger stem diameter, more leaves, fewer fallen leaves, and larger total leaf area than plants that were grown under high VPD. Initially, low VPD increased height growth rate and stomatal conductance; however, the effect was transient and the differences between low and high VPD plants became smaller with time. Metabolic adjustment to low VPD reflected N deficiency. The concentrations of N, iron, chlorophyll, amino acids, and soluble carbohydrates were lower and the levels of starch, quercetin glycosides, and raffinose were higher in the leaves that had developed under low VPD compared with high VPD. Additional N supply did not fully overcome the negative effect of low VPD on nutrient status but it diminished the effects of low VPD on leaf metabolism. Thus, with high N supply, the glutamine to glutamate ratio and starch production under low VPD became comparable with the levels under high VPD. The present study demonstrates that low VPD affects carbon and nutrient homeostasis and modifies N allocation of plants. PMID:27259554

  20. Plant growth is influenced by glutamine synthetase-catalyzed nitrogen metabolism

    SciTech Connect

    Langston-Unkefer, P.J.

    1991-06-11

    Ammonia assimilation has been implicated as participating in regulation of nitrogen fixation in free-living bacteria. In fact, these simple organisms utilize an integrated regulation of carbon and nitrogen metabolism; we except to observe an integration of nitrogen and carbon fixation in plants; how could these complex systems grow efficiently and compete in the ecosystem without coordinating these two crucial activities We have been investigating the role of ammonia assimilation regulating the complex symbiotic nitrogen fixation of legumes. Just as is observed in the simple bacterial systems, perturbation of ammonia assimilation in legumes results in increased overall nitrogen fixation. The perturbed plants have increased growth and total nitrogen fixation capability. Because we have targeted the first enyzme in ammonia assimilation, glutamine synthetase, this provides a marker that could be used to assist selection or screening for increased biomass yield. 45 refs., 4 tabs.

  1. Deletion of Type I glutamine synthetase deregulates nitrogen metabolism and increases ethanol production in Clostridium thermocellum.

    PubMed

    Rydzak, Thomas; Garcia, David; Stevenson, David M; Sladek, Margaret; Klingeman, Dawn M; Holwerda, Evert K; Amador-Noguez, Daniel; Brown, Steven D; Guss, Adam M

    2017-04-08

    Clostridium thermocellum rapidly deconstructs cellulose and ferments resulting hydrolysis products into ethanol and other products, and is thus a promising platform organism for the development of cellulosic biofuel production via consolidated bioprocessing. While recent metabolic engineering strategies have targeted eliminating canonical fermentation products (acetate, lactate, formate, and H2), C. thermocellum also secretes amino acids, which has limited ethanol yields in engineered strains to approximately 70% of the theoretical maximum. To investigate approaches to decrease amino acid secretion, we attempted to reduce ammonium assimilation by deleting the Type I glutamine synthetase (glnA) in an essentially wild type strain of C. thermocellum. Deletion of glnA reduced levels of secreted valine and total amino acids by 53% and 44% respectively, and increased ethanol yields by 53%. RNA-seq analysis revealed that genes encoding the RNF-complex were more highly expressed in ΔglnA and may have a role in improving NADH-availability for ethanol production. While a significant up-regulation of genes involved in nitrogen assimilation and urea uptake suggested that deletion of glnA induces a nitrogen starvation response, metabolomic analysis showed an increase in intracellular glutamine levels indicative of nitrogen-rich conditions. We propose that deletion of glnA causes deregulation of nitrogen metabolism, leading to overexpression of nitrogen metabolism genes and, in turn, elevated glutamine levels. Here we demonstrate that perturbation of nitrogen assimilation is a promising strategy to redirect flux from the production of nitrogenous compounds toward biofuels in C. thermocellum.

  2. Characterizing the Network of Drugs and Their Affected Metabolic Subpathways

    PubMed Central

    Li, Jing; Han, Junwei; Wang, Shuyuan; Yao, Qianlan; Wang, Yingying; Zhang, Yunpeng; Zhang, Chunlong; Xu, Yanjun; Jiang, Wei; Li, Xia

    2012-01-01

    A fundamental issue in biology and medicine is illustration of the overall drug impact which is always the consequence of changes in local regions of metabolic pathways (subpathways). To gain insights into the global relationship between drugs and their affected metabolic subpathways, we constructed a drug–metabolic subpathway network (DRSN). This network included 3925 significant drug–metabolic subpathway associations representing drug dual effects. Through analyses based on network biology, we found that if drugs were linked to the same subpathways in the DRSN, they tended to share the same indications and side effects. Furthermore, if drugs shared more subpathways, they tended to share more side effects. We then calculated the association score by integrating drug-affected subpathways and disease-related subpathways to quantify the extent of the associations between each drug class and disease class. The results showed some close drug–disease associations such as sex hormone drugs and cancer suggesting drug dual effects. Surprisingly, most drugs displayed close associations with their side effects rather than their indications. To further investigate the mechanism of drug dual effects, we classified all the subpathways in the DRSN into therapeutic and non-therapeutic subpathways representing drug therapeutic effects and side effects. Compared to drug side effects, the therapeutic effects tended to work through tissue-specific genes and these genes tend to be expressed in the adrenal gland, liver and kidney; while drug side effects always occurred in the liver, bone marrow and trachea. Taken together, the DRSN could provide great insights into understanding the global relationship between drugs and metabolic subpathways. PMID:23112813

  3. Influences of nano-anatase TiO2 on the nitrogen metabolism of growing spinach.

    PubMed

    Yang, Fan; Hong, Fashui; You, Wenjuan; Liu, Chao; Gao, Fengqing; Wu, Cheng; Yang, Ping

    2006-05-01

    Previous research showed that nano-TiO2 could significantly promote photosynthesis and greatly improve growth of spinach, but we also speculated that an increase of spinach growth by nano-TiO2 treatment might be closely related to the change of nitrogen metabolism. The effects of nanoanatase TiO2 on the nitrogen metabolism of growing spinach were studied by treating them with nano-anatase TiO2. The results showed that nano-anatase TiO2 treatment could obviously increase the activities of nitrate reductase, glutamate dehydrogenase, glutamine synthase, and glutamic-pyruvic transaminase during the growing stage. Nano-anatase TiO2 treatment could also promote spinach to absorb nitrate, accelerate inorganic nitrogen (such as NO3--N and NH4+-N) to be translated into organic nitrogen (such as protein and chlorophyll), and enhance the fresh weight and dry weights.

  4. FACTORS AFFECTING SENSITIVITY OF CHEMICAL AND ECOLOGICAL RESPONSES OF MARINE EMBAYMEMTS TO NITROGEN LOADING

    EPA Science Inventory

    This paper summarizes an ongoing examination of the primary factors that affect sensitivity of marine embayment responses to nitrogen loading. Included is a discussion of two methods for using these factors: classification of embayments into discrete sensitivity classes and norma...

  5. Novel Metabolic Attributes of the Genus Cyanothece, Comprising a Group of Unicellular Nitrogen-Fixing Cyanobacteria

    PubMed Central

    Bandyopadhyay, Anindita; Elvitigala, Thanura; Welsh, Eric; Stöckel, Jana; Liberton, Michelle; Min, Hongtao; Sherman, Louis A.; Pakrasi, Himadri B.

    2011-01-01

    ABSTRACT The genus Cyanothece comprises unicellular cyanobacteria that are morphologically diverse and ecologically versatile. Studies over the last decade have established members of this genus to be important components of the marine ecosystem, contributing significantly to the nitrogen and carbon cycle. System-level studies of Cyanothece sp. ATCC 51142, a prototypic member of this group, revealed many interesting metabolic attributes. To identify the metabolic traits that define this class of cyanobacteria, five additional Cyanothece strains were sequenced to completion. The presence of a large, contiguous nitrogenase gene cluster and the ability to carry out aerobic nitrogen fixation distinguish Cyanothece as a genus of unicellular, aerobic nitrogen-fixing cyanobacteria. Cyanothece cells can create an anoxic intracellular environment at night, allowing oxygen-sensitive processes to take place in these oxygenic organisms. Large carbohydrate reserves accumulate in the cells during the day, ensuring sufficient energy for the processes that require the anoxic phase of the cells. Our study indicates that this genus maintains a plastic genome, incorporating new metabolic capabilities while simultaneously retaining archaic metabolic traits, a unique combination which provides the flexibility to adapt to various ecological and environmental conditions. Rearrangement of the nitrogenase cluster in Cyanothece sp. strain 7425 and the concomitant loss of its aerobic nitrogen-fixing ability suggest that a similar mechanism might have been at play in cyanobacterial strains that eventually lost their nitrogen-fixing ability. PMID:21972240

  6. Cerium relieves the inhibition of nitrogen metabolism of spinach caused by magnesium deficiency.

    PubMed

    Yin, Sitao; Ze, Yuguan; Liu, Chao; Li, Na; Zhou, Min; Duan, Yanmei; Hong, Fashui

    2009-12-01

    Magnesium is one of the essential elements for plant growth and cerium is a beneficial element for plant growth. However, the effects of the fact that cerium improves the nitrogen metabolism of plants under magnesium deficiency is poorly understood. The main aim of the study was to determine the role of cerium in the amelioration of magnesium-deficiency effects in spinach plants. Spinach plants were cultivated in Hoagland's solution. They were subjected to magnesium deficiency and to cerium chloride administered in the magnesium-present media and magnesium-deficient media. Spinach plants grown in the magnesium-present media and magnesium-deficient media were measured for key enzyme activities involved in nitrogen metabolism such as nitrate reductase, nitrite reductase, glutamate dehydrogenase, glutamate synthase, urease, glutamic–pyruvic transaminase, and glutamic–oxaloace protease transaminase. As the nitrogen metabolism in spinach was significantly inhibited by magnesium deficiency, it caused a significant reduction of spinach plant weight, leaf turning chlorosis. However, cerium treatment grown in magnesium-deficiency media significantly promoted the activities of the key enzymes as well as the contents of the free amino acids, chlorophyll, soluble protein, and spinach growth. It implied that Ce3+ could partly substitute for magnesium to facilitate the transformation from inorganic nitrogen to organic nitrogen, leading to the improvement of spinach growth, although the metabolism needs to be investigated further.

  7. Metabolomics Reveals Cryptic Interactive Effects of Species Interactions and Environmental Stress on Nitrogen and Sulfur Metabolism in Seagrass.

    PubMed

    Hasler-Sheetal, Harald; Castorani, Max C N; Glud, Ronnie N; Canfield, Donald E; Holmer, Marianne

    2016-11-01

    Eutrophication of estuaries and coastal seas is accelerating, increasing light stress on subtidal marine plants and changing their interactions with other species. To date, we have limited understanding of how such variations in environmental and biological stress modify the impact of interactions among foundational species and eventually affect ecosystem health. Here, we used metabolomics to assess the impact of light reductions on interactions between the seagrass Zostera marina, an important habitat-forming marine plant, and the abundant and commercially important blue mussel Mytilus edulis. Plant performance varied with light availability but was unaffected by the presence of mussels. Metabolomic analysis, on the other hand, revealed an interaction between light availability and presence of M. edulis on seagrass metabolism. Under high light, mussels stimulated seagrass nitrogen and energy metabolism. Conversely, in low light mussels impeded nitrogen and energy metabolism, and enhanced responses against sulfide toxicity, causing inhibited oxidative energy metabolism and tissue degradation. Metabolomic analysis thereby revealed cryptic changes to seagrass condition that could not be detected by traditional approaches. Our findings suggest that coastal eutrophication and associated reductions in light may shift seagrass-bivalve interactions from mutualistic to antagonistic, which is important for conservation management of seagrass meadows.

  8. The nature of the nitrogen source added to nitrogen depleted vinifications conducted by a Saccharomyces cerevisiae strain in synthetic must affects gene expression and the levels of several volatile compounds.

    PubMed

    Jiménez-Martí, Elena; Aranda, Agustín; Mendes-Ferreira, Alexandra; Mendes-Faia, Arlete; del Olmo, Marcel Lí

    2007-07-01

    Nitrogen starvation may lead to stuck and sluggish fermentations. These undesirable situations result in wines with high residual sugar, longer vinification times, and risks of microbial contamination. The typical oenological method to prevent these problems is the early addition of ammonium salts to the grape juice, although excessive levels of these compounds may lead to negative consequences for the final product. This addition reduces the overall fermentation time, regardless of the time of addition, but the effect is more significant when nitrogen is added during the yeast exponential phase. In this work we analysed the effect of adding different nitrogen sources (ammonia, amino acids or a combination of both) under nitrogen depletion in order to understand yeast metabolic changes that lead to the adaptation to the new conditions. These studies were carried out in a synthetic must that mimics the composition of the natural must. Furthermore, we studied how this addition affects fermentative behaviour, the levels of several yeast volatile compounds in the final product, arginase activity, and the expression of several genes involved in stress response and nitrogen metabolism during vinification. We found that the nature of the nitrogen source added during yeast late exponential growth phase introduces changes to the volatile compounds profile and to the gene expression. On the other hand, arginase activity and the expression of the stress response gene ACA1 are useful to monitor nitrogen depletion/addition during growth of the wine yeast considered under our vinification conditions.

  9. Nitrogen fertilizer rate affects root exudation, the rhizosphere microbiome and nitrogen-use-efficiency of maize

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The composition and function of microbial communities present in the rhizosphere of crops has been linked to edaphic factors and root exudate composition. In this paper, we examined the effect of N fertilizer rate on maize root exudation, the associated rhizosphere community, and nitrogen-use-effici...

  10. Rearrangement of nitrogen metabolism in rice (Oryza sativa L.) under salt stress.

    PubMed

    Xu, Jianwen; Huang, Xi; Lan, Hongxia; Zhang, Hongsheng; Huang, Ji

    2016-01-01

    Salt stress is an important environmental condition limiting the agricultural production. The reprogram of protein expression is one of the strategies of plants to cope with salt stress. We have previously analyzed the photosynthesis, antioxidant and oxidative phosphorylation involved in the carbon metabolism and the redox metabolism in rice seedlings under salt stress. Here, we focused on the proteins involved in nitrogen metabolic response. As it was reported that the nitrite uptake was enhanced in Arabidopsis PII knock-out mutants, the down-regulation of P-II nitrogen sensing protein in rice probably contributes to the accumulation of amino acids under stress. In addition, the protein synthesis is limited by the decrease of related proteins, and more amino acids could be used as the compatible solute. Hence, our study indicates that the rearrangement of nitrogen metabolism under salt stress could accumulate more amino acids as the compatible solute rather than the components of proteins. This study provides information for an improved understanding of nitrogen metabolic response to salt stress in rice.

  11. Evolutionary convergence and nitrogen metabolism in Blattabacterium strain Bge, primary endosymbiont of the cockroach Blattella germanica.

    PubMed

    López-Sánchez, Maria J; Neef, Alexander; Peretó, Juli; Patiño-Navarrete, Rafael; Pignatelli, Miguel; Latorre, Amparo; Moya, Andrés

    2009-11-01

    Bacterial endosymbionts of insects play a central role in upgrading the diet of their hosts. In certain cases, such as aphids and tsetse flies, endosymbionts complement the metabolic capacity of hosts living on nutrient-deficient diets, while the bacteria harbored by omnivorous carpenter ants are involved in nitrogen recycling. In this study, we describe the genome sequence and inferred metabolism of Blattabacterium strain Bge, the primary Flavobacteria endosymbiont of the omnivorous German cockroach Blattella germanica. Through comparative genomics with other insect endosymbionts and free-living Flavobacteria we reveal that Blattabacterium strain Bge shares the same distribution of functional gene categories only with Blochmannia strains, the primary Gamma-Proteobacteria endosymbiont of carpenter ants. This is a remarkable example of evolutionary convergence during the symbiotic process, involving very distant phylogenetic bacterial taxa within hosts feeding on similar diets. Despite this similarity, different nitrogen economy strategies have emerged in each case. Both bacterial endosymbionts code for urease but display different metabolic functions: Blochmannia strains produce ammonia from dietary urea and then use it as a source of nitrogen, whereas Blattabacterium strain Bge codes for the complete urea cycle that, in combination with urease, produces ammonia as an end product. Not only does the cockroach endosymbiont play an essential role in nutrient supply to the host, but also in the catabolic use of amino acids and nitrogen excretion, as strongly suggested by the stoichiometric analysis of the inferred metabolic network. Here, we explain the metabolic reasons underlying the enigmatic return of cockroaches to the ancestral ammonotelic state.

  12. Effect of Chromium(VI) Toxicity on Enzymes of Nitrogen Metabolism in Clusterbean (Cyamopsis tetragonoloba L.)

    PubMed Central

    Sangwan, Punesh; Joshi, U. N.

    2014-01-01

    Heavy metals are the intrinsic component of the environment with both essential and nonessential types. Their excessive levels pose a threat to plant growth and yield. Also, some heavy metals are toxic to plants even at very low concentrations. The present investigation (a pot experiment) was conducted to determine the affects of varying chromium(VI) levels (0.0, 0.5, 1.0, 2.0, and 4.0 mg chromium(VI) kg−1 soil in the form of potassium dichromate) on the key enzymes of nitrogen metabolism in clusterbean. Chromium treatment adversely affect nitrogenase, nitrate reductase, nitrite reductase, glutamine synthetase, and glutamate dehydrogenase in various plant organs at different growth stages as specific enzyme activity of these enzymes decreased with an increase in chromium(VI) levels from 0 to 2.0 mg chromium(VI) kg−1 soil and 4.0 mg chromium(VI) kg−1 soil was found to be lethal to clusterbean plants. In general, the enzyme activity increased with advancement of growth to reach maximum at flowering stage and thereafter decreased at grain filling stage. PMID:24744916

  13. Influence of vitamin B auxotrophy on nitrogen metabolism in eukaryotic phytoplankton

    PubMed Central

    Bertrand, Erin M.; Allen, Andrew E.

    2012-01-01

    While nitrogen availability is known to limit primary production in large parts of the ocean, vitamin starvation amongst eukaryotic phytoplankton is becoming increasingly recognized as an oceanographically relevant phenomenon. Cobalamin (B12) and thiamine (B1) auxotrophy are widespread throughout eukaryotic phytoplankton, with over 50% of cultured isolates requiring B12 and 20% requiring B1. The frequency of vitamin auxotrophy in harmful algal bloom species is even higher. Instances of colimitation between nitrogen and B vitamins have been observed in marine environments, and interactions between these nutrients have been shown to impact phytoplankton species composition. This review surveys available data, including relevant gene expression patterns, to evaluate the potential for interactive effects of nitrogen and vitamin B12 and B1 starvation in eukaryotic phytoplankton. B12 plays essential roles in amino acid and one-carbon metabolism, while B1 is important for primary carbohydrate and amino acid metabolism and likely useful as an anti-oxidant. Here we will focus on three potential metabolic interconnections between vitamin, nitrogen, and sulfur metabolism that may have ramifications for the role of vitamin and nitrogen scarcities in driving ocean productivity and species composition. These include: (1) B12, B1, and N starvation impacts on osmolyte and antioxidant production, (2) B12 and B1 starvation impacts on polyamine biosynthesis, and (3) influence of B12 and B1 starvation on the diatom urea cycle and amino acid recycling through impacts on the citric acid cycle. We evaluate evidence for these interconnections and identify oceanographic contexts in which each may impact rates of primary production and phytoplankton community composition. Major implications include that B12 and B1 deprivation may impair the ability of phytoplankton to recover from nitrogen starvation and that changes in vitamin and nitrogen availability may synergistically impact harmful

  14. Metabolic and morphological changes of an oil accumulating trebouxiophycean alga in nitrogen-deficient conditions.

    PubMed

    Ito, Takuro; Tanaka, Miho; Shinkawa, Haruka; Nakada, Takashi; Ano, Yoshitaka; Kurano, Norihide; Soga, Tomoyoshi; Tomita, Masaru

    2013-03-01

    Oil-rich algae have promising potential for a next-generation biofuel feedstock. Pseudochoricystis ellipsoidea MBIC 11204, a novel unicellular green algal strain, accumulates a large amount of oil (lipids) in nitrogen-deficient (-N) conditions. Although the oil bodies are easily visualized by lipophilic staining in the cells, little is known about how oil bodies are metabolically synthesized. Clarifying the metabolic profiles in -N conditions is important to understand the physiological mechanisms of lipid accumulations and will be useful to optimize culture conditions efficiently produce industrial oil. Metabolome and lipidome profiles were obtained, respectively, using capillary electrophoresis- and liquid chromatography-mass spectrometry from P. ellipsoidea in both nitrogen-rich (+N; rapid growth) and -N conditions. Relative quantities of more than 300 metabolites were systematically compared between these two conditions. Amino acids in nitrogen assimilation and N-transporting metabolisms were decreased to 1/20 the amount, or less, in -N conditions. In lipid metabolism, the quantities of neutral lipids increased greatly in -N conditions; however, quantities of nearly all the other lipids either decreased or only changed slightly. The morphological changes in +N and -N conditions were also provided by microscopy, and we discuss their relationship to the metabolic changes. This is the first approach to understand the novel algal strain's metabolism using a combination of wide-scale metabolome analysis and morphological analysis.

  15. A Natural Light/Dark Cycle Regulation of Carbon-Nitrogen Metabolism and Gene Expression in Rice Shoots.

    PubMed

    Li, Haixing; Liang, Zhijun; Ding, Guangda; Shi, Lei; Xu, Fangsen; Cai, Hongmei

    2016-01-01

    Light and temperature are two particularly important environmental cues for plant survival. Carbon and nitrogen are two essential macronutrients required for plant growth and development, and cellular carbon and nitrogen metabolism must be tightly coordinated. In order to understand how the natural light/dark cycle regulates carbon and nitrogen metabolism in rice plants, we analyzed the photosynthesis, key carbon-nitrogen metabolites, and enzyme activities, and differentially expressed genes and miRNAs involved in the carbon and nitrogen metabolic pathway in rice shoots at the following times: 2:00, 6:00, 10:00, 14:00, 18:00, and 22:00. Our results indicated that more CO2 was fixed into carbohydrates by a high net photosynthetic rate, respiratory rate, and stomatal conductance in the daytime. Although high levels of the nitrate reductase activity, free ammonium and carbohydrates were exhibited in the daytime, the protein synthesis was not significantly facilitated by the light and temperature. In mRNA sequencing, the carbon and nitrogen metabolism-related differentially expressed genes were obtained, which could be divided into eight groups: photosynthesis, TCA cycle, sugar transport, sugar metabolism, nitrogen transport, nitrogen reduction, amino acid metabolism, and nitrogen regulation. Additionally, a total of 78,306 alternative splicing events have been identified, which primarily belong to alternative 5' donor sites, alternative 3' acceptor sites, intron retention, and exon skipping. In sRNA sequencing, four carbon and nitrogen metabolism-related miRNAs (osa-miR1440b, osa-miR2876-5p, osa-miR1877 and osa-miR5799) were determined to be regulated by natural light/dark cycle. The expression level analysis showed that the four carbon and nitrogen metabolism-related miRNAs negatively regulated their target genes. These results may provide a good strategy to study how natural light/dark cycle regulates carbon and nitrogen metabolism to ensure plant growth and

  16. Integration of Carbon, Nitrogen, and Oxygen Metabolism in Escherichia coli

    DTIC Science & Technology

    2012-10-22

    environmental fluctuations. As growth can be limited by the scarcity of any one nutrient, the rate at which each nutrient is assimilated must be...multiple nutrient systems. We discovered that the carbonaceous substrate of nitrogen assimilation , α-ketoglutarate, directly inhibits glucose uptake and...at which each nutrient is  assimilated  must be sensitive not only to  its own availability, but also to that of other nutrients. Remarkably, across

  17. The form of nitrogen nutrition affects resistance against Pseudomonas syringae pv. phaseolicola in tobacco

    PubMed Central

    Gupta, Kapuganti J.; Mur, Luis A. J.

    2013-01-01

    Different forms of nitrogen (N) fertilizer affect disease development; however, this study investigated the effects of N forms on the hypersensitivity response (HR)—a pathogen-elicited cell death linked to resistance. HR-eliciting Pseudomonas syringae pv. phaseolicola was infiltrated into leaves of tobacco fed with either or . The speed of cell death was faster in -fed compared with -fed plants, which correlated, respectively, with increased and decreased resistance. Nitric oxide (NO) can be generated by nitrate reductase (NR) to influence the formation of the HR. NO generation was reduced in -fed plants where N assimilation bypassed the NR step. This was similar to that elicited by the disease-forming P. syringae pv. tabaci strain, further suggesting that resistance was compromised with feeding. PR1a is a biomarker for the defence signal salicylic acid (SA), and expression was reduced in -fed compared with fed plants at 24h after inoculation. This pattern correlated with actual SA measurements. Conversely, total amino acid, cytosolic and apoplastic glucose/fructose and sucrose were elevated in - treated plants. Gas chromatography/mass spectroscopy was used to characterize metabolic events following different N treatments. Following nutrition, polyamine biosynthesis was predominant, whilst after nutrition, flux appeared to be shifted towards the production of 4-aminobutyric acid. The mechanisms whereby feeding enhances SA, NO, and polyamine-mediated HR-linked defence whilst these are compromised with , which also increases the availability of nutrients to pathogens, are discussed. PMID:23230025

  18. Nitrous oxide emissions affected by biochar and nitrogen stabilizers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Both biochar and N fertilizer stabilizers (N transformation inhibitors) are potential strategies to reduce nitrous oxide (N2O) emissions from fertilization, but the mechanisms and/or N transformation processes affecting the N dynamics are not fully understood. This research investigated N2O emission...

  19. Arginine supplementation does not alter nitrogen metabolism of beef steers during a lipopolysaccharide challenge

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Demand for arginine (Arg) is reported to increase during immune challenges. This study evaluated effects of lipopolysaccharide (LPS) and abomasal Arg infusion on nitrogen (N) metabolism and immune response of 20 ruminally cannulated steers (369 ± 46 kg BW) in a randomized block design. Each block co...

  20. Prochlorococcus Genetic Transformation and the Genomics of Nitrogen Metabolism

    DTIC Science & Technology

    2005-09-01

    expression of rbp-2 RNAi (Table 2) (18). rbp-2 might spe - tothenate kinases in C. elegans , the rate-limit- each gene and to determine whether life-span...genes to and from Prochlorococcus viruses ...... 82-87 Appendix III Daf-16 Target genes that control C. elegans life-span and metabolism ...... 88-91... mutations in the host chromosome. Transposon mutagenesis has been widely used in other cyanobacteria as a means to randomly inactivate gene function

  1. Rapid peptide metabolism: A major component of soil nitrogen cycling?

    NASA Astrophysics Data System (ADS)

    Farrell, Mark; Hill, Paul W.; Wanniarachchi, Sudas D.; Farrar, John; Bardgett, Richard D.; Jones, Davey L.

    2011-09-01

    Proteinaceous and peptidic nitrogen is a potential direct nutrient source for both plants and microbes in the soil, without prior degradation to amino acids and mineralization. We used a series of five sites along an elevation gradient from 15 m a.s.l. to 710 m a.s.l. along which primary productivity decreases to investigate peptide utilization rates by soil microbes. Using 14C-labeled L-alanine, L-dialanine, and L-trialanine in a series of incubation experiments, we show that peptides are directly and rapidly assimilated by soil microbes, and that they are utilized for both biomass production and respiration. Alanine, dialanine, and trialanine were mineralized rapidly by soil microbes from the five sites along the gradient. Across all five sites, dialanine and trialanine were mineralized faster than alanine. In competition experiments, a 100-fold excess of alanine had no effect on the rate of trialanine mineralization in four of the five sites, and the same excess of trialanine had no effect on alanine mineralization. This is indicative of uptake of the intact peptide by the soil microbial community. Our findings have implications for understanding terrestrial nitrogen cycling because they point to a short-circuit whereby large peptides and proteins need only be extracellularly cleaved to short chain length peptides before direct assimilation by microbes.

  2. Exogenously applied nitrate improves the photosynthetic performance and nitrogen metabolism in tomato (Solanumlycopersicum L. cv Pusa Rohini) under arsenic (V) toxicity.

    PubMed

    Agnihotri, Ashish; Seth, Chandra Shekhar

    2016-07-01

    Tomato (Solanum lycopersicum L.) being a widespread and most commonly consumed vegetable all over the world has an important economic value for its producers and related food industries. It is a serious matter of concern as its production is affected by arsenic present in soil. So, the present study, investigated the toxicity of As(V) on photosynthetic performance along with nitrogen metabolism and its alleviation by exogenous application of nitrate. Plants were grown under natural conditions using soil spiked with 25 mg and 20 mM, As(V) and nitrate, respectively. Our results revealed that plant growth indices, photosynthetic pigments, and other major photosynthetic parameters like net photosynthetic rate and maximum quantum efficiency (Fv/Fm ) of photosystem II (PSII) were significantly (P ≤ 0.05) reduced under As(V) stress. However, nitrate application significantly (P ≤ 0.05) alleviated As(V) toxicity by improving the aforesaid plant responses and also restored the abnormal shape of guard cells. Nitrogen metabolism was assessed by studying the key nitrogen-metabolic enzymes. Exogenous nitrate revamped nitrogen metabolism through a major impact on activities of NR, NiR, GS and GOGAT enzymes and also enhanced the total nitrogen and NO content while malondialdehyde content, and membrane electrolytic leakage were remarkably reduced. Our study suggested that exogenous nitrate application could be considered as a cost effective approach in ameliorating As(V) toxicity.

  3. Respiration, metabolic balance, and attention in affective picture processing.

    PubMed

    Gomez, Patrick; Shafy, Samiha; Danuser, Brigitta

    2008-05-01

    The respiratory behavior during affective states is not completely understood. We studied breathing pattern responses to picture series in 37 participants. We also measured end-tidal pCO2 (EtCO2) to determine if ventilation is in balance with metabolic demands and spontaneous eye-blinking to investigate the link between respiration and attention. Minute ventilation (MV) and inspiratory drive increased with self-rated arousal. These relationships reflected increases in inspiratory volume rather than shortening of the time parameters. EtCO2 covaried with pleasantness but not arousal. Eye-blink rate decreased with increasing unpleasantness in line with a negativity bias in attention. This study confirms that respiratory responses to affective stimuli are organized to a certain degree along the dimensions of valence and arousal. It shows, for the first time, that during picture viewing, ventilatory increases with increasing arousal are in balance with metabolic activity and that inspiratory volume is modulated by arousal. MV emerges as the most reliable respiratory index of self-perceived arousal.

  4. Interactions between dietary boron and thiamine affect lipid metabolism

    SciTech Connect

    Herbel, J.L.; Hunt, C.D. )

    1991-03-15

    An experiment was designed to test the hypothesis that dietary boron impacts upon the function of various coenzymes involved in energy metabolism. In a 2 {times} 7 factorially-arranged experiment, weanling, vitamin D{sub 3}-deprived rats were fed a ground corn-casein-corn oil based diet supplemented with 0 or 2 mg boron/kg and 50% of the requirement for thiamine (TM), riboflavin (RF), pantothenic acid (PA) or pyridoxine (PX); 0% for folic acid (FA) or nicotinic acid (NA). All vitamins were supplemented in adequate amounts in the control diet. At 8 weeks of age, the TM dietary treatment was the one most affected by supplemental dietary boron (SDB). In rats that were fed 50% TM, SDB increased plasma concentrations of triglyceride (TG) and activity of alanine transaminase (ALT), and the liver to body weight (L/B) ratio. However, in the SDB animals, adequate amounts of TM decreased the means of those variables to near that observed in non-SDB rats fed 50% TM. The findings suggest that an interaction between dietary boron and TM affects lipid metabolism.

  5. Osteoid osteoma is an osteocalcinoma affecting glucose metabolism.

    PubMed

    Confavreux, C B; Borel, O; Lee, F; Vaz, G; Guyard, M; Fadat, C; Carlier, M-C; Chapurlat, R; Karsenty, G

    2012-05-01

    Osteocalcin is a hormone secreted by osteoblasts, which regulates energy metabolism by increasing β-cell proliferation, insulin secretion, insulin sensitivity, and energy expenditure. This has been demonstrated in mice, but to date, the evidence implicating osteocalcin in the regulation of energy metabolism in humans are indirect. To address this question more directly, we asked whether a benign osteoblastic tumor, such as osteoma osteoid in young adults, may secrete osteocalcin. The study was designed to assess the effect of surgical resection of osteoid osteoma on osteocalcin and blood glucose levels in comparison with patients undergoing knee surgery and healthy volunteers. Blood collections were performed the day of surgery and the following morning after overnight fasting. Patients and controls were recruited in the orthopedic surgery department of New York Presbiterian Hospital, NY-USA and Hospices Civils de Lyon, France. Seven young males were included in the study: two had osteoid osteoma, two underwent knee surgery, and three were healthy volunteers. After resection of the osteoid osteomas, we observed a decrease of osteocalcin by 62% and 30% from the initial levels. Simultaneously, blood glucose increased respectively by 32% and 15%. Bone turnover markers were not affected. This case study shows for the first time that osteocalcin in humans affects blood glucose level. This study also suggests that ostoid osteoma may be considered, at least in part, as an osteocalcinoma.

  6. SO(2) protects the amino nitrogen metabolism of Saccharomyces cerevisiae under thermal stress.

    PubMed

    Ancín-Azpilicueta, Carmen; Barriuso-Esteban, Blanca; Nieto-Rojo, Rodrigo; Aristizábal-López, Nerea

    2012-09-01

    Thermal stress conditions during alcoholic fermentation modify yeasts' plasma membrane since they become more hyperfluid, which results in a loss of bilayer integrity. In this study, the influence of elevated temperatures on nitrogen metabolism of a Saccharomyces cerevisiae strain was studied, as well as the effect of different concentrations of SO(2) on nitrogen metabolism under thermal stress conditions. The results obtained revealed that amino nitrogen consumption was lower in the fermentation sample subjected to thermal stress than in the control, and differences in amino acid consumption preferences were also detected, especially at the beginning of the fermentation. Under thermal stress conditions, among the three doses of SO(2) studied (0, 35, 70 mg l(-1) SO(2) ), the highest dose was observed to favour amino acid utilization during the fermentative process, whereas sugar consumption presented higher rates at medium doses.

  7. Remodeling of intermediate metabolism in the diatom Phaeodactylum tricornutum under nitrogen stress

    PubMed Central

    Levitan, Orly; Dinamarca, Jorge; Zelzion, Ehud; Lun, Desmond S.; Guerra, L. Tiago; Kim, Min Kyung; Kim, Joomi; Van Mooy, Benjamin A. S.; Bhattacharya, Debashish; Falkowski, Paul G.

    2015-01-01

    Diatoms are unicellular algae that accumulate significant amounts of triacylglycerols as storage lipids when their growth is limited by nutrients. Using biochemical, physiological, bioinformatics, and reverse genetic approaches, we analyzed how the flux of carbon into lipids is influenced by nitrogen stress in a model diatom, Phaeodactylum tricornutum. Our results reveal that the accumulation of lipids is a consequence of remodeling of intermediate metabolism, especially reactions in the tricarboxylic acid and the urea cycles. Specifically, approximately one-half of the cellular proteins are cannibalized; whereas the nitrogen is scavenged by the urea and glutamine synthetase/glutamine 2-oxoglutarate aminotransferase pathways and redirected to the de novo synthesis of nitrogen assimilation machinery, simultaneously, the photobiological flux of carbon and reductants is used to synthesize lipids. To further examine how nitrogen stress triggers the remodeling process, we knocked down the gene encoding for nitrate reductase, a key enzyme required for the assimilation of nitrate. The strain exhibits 40–50% of the mRNA copy numbers, protein content, and enzymatic activity of the wild type, concomitant with a 43% increase in cellular lipid content. We suggest a negative feedback sensor that couples photosynthetic carbon fixation to lipid biosynthesis and is regulated by the nitrogen assimilation pathway. This metabolic feedback enables diatoms to rapidly respond to fluctuations in environmental nitrogen availability. PMID:25548193

  8. Carbon and Nitrogen Provisions Alter the Metabolic Flux in Developing Soybean Embryos1[W][OA

    PubMed Central

    Allen, Doug K.; Young, Jamey D.

    2013-01-01

    Soybean (Glycine max) seeds store significant amounts of their biomass as protein, levels of which reflect the carbon and nitrogen received by the developing embryo. The relationship between carbon and nitrogen supply during filling and seed composition was examined through a series of embryo-culturing experiments. Three distinct ratios of carbon to nitrogen supply were further explored through metabolic flux analysis. Labeling experiments utilizing [U-13C5]glutamine, [U-13C4]asparagine, and [1,2-13C2]glucose were performed to assess embryo metabolism under altered feeding conditions and to create corresponding flux maps. Additionally, [U-14C12]sucrose, [U-14C6]glucose, [U-14C5]glutamine, and [U-14C4]asparagine were used to monitor differences in carbon allocation. The analyses revealed that: (1) protein concentration as a percentage of total soybean embryo biomass coincided with the carbon-to-nitrogen ratio; (2) altered nitrogen supply did not dramatically impact relative amino acid or storage protein subunit profiles; and (3) glutamine supply contributed 10% to 23% of the carbon for biomass production, including 9% to 19% of carbon to fatty acid biosynthesis and 32% to 46% of carbon to amino acids. Seed metabolism accommodated different levels of protein biosynthesis while maintaining a consistent rate of dry weight accumulation. Flux through ATP-citrate lyase, combined with malic enzyme activity, contributed significantly to acetyl-coenzyme A production. These fluxes changed with plastidic pyruvate kinase to maintain a supply of pyruvate for amino and fatty acids. The flux maps were independently validated by nitrogen balancing and highlight the robustness of primary metabolism. PMID:23314943

  9. Oxygenation of Earth's atmosphere and its impact on the evolution of nitrogen-based metabolisms

    NASA Astrophysics Data System (ADS)

    Papineau, D.; Mojzsis, S. J.

    2002-12-01

    The evolution of metabolic pathways is closely linked to the evolution of the redox state of the terrestrial atmosphere. Nitrogen has been an essential biological element since the emergence of life when reduced nitrogen compounds (e.g. ammonia) were utilized in the prebiotic synthesis of proteins and nucleic acids. The nitrogen isotopic composition of sediments has been used to trace the origin of sedimentary organic matter in the rock record. Nitrogen is therefore suitable as a biosignature to trace the emergence of life on Earth or other planetary bodies as well as to follow the subsequent evolution of the biosphere in response to global redox changes. Evidence is strong that biological nitrogen fixation evolved very early in the history of life. The Last Common Ancestor (LCA) on Earth was most likely capable of nitrogen fixation as seen from the phylogenetic distribution of nitrogen-fixing organisms in both the domains of Bacteria and Archaea. Phylogenetic trees plotted with nitrogen-fixing gene (Nif) sequences from lineages of Bacteria and Archaea suggest that the Nif genes originated in a common ancestor of the two domains. Other phylogenetic analyses have also demonstrated that the paralogous duplication of the nifDK and nifEN operons, central to nitrogen fixation, predated the divergence of Archaea from Bacteria and therefore occurred prior to the emergence of the LCA. Although the same may be true for denitrification, this metabolic pathway probably did not become dominant until atmospheric pO2 increased between ~2.4 to 1.9 Ga during the Great Oxygenation Event (GOE). Recent work has shown a general depletion in 15N content of Archean (pre-2.5 Ga) relative to Phanerozoic (<540 Ma) kerogens. Studies have shown that the distribution of the δ15N values in kerogens shift from negative values in the Early Archean (from -6 to +6‰ with an average near 0‰ ) to approximately contemporary positive values (from +2 to +10‰ with an average at +6‰ ) by the

  10. Characterizing bacterial gene expression in nitrogen cycle metabolism with RT-qPCR.

    PubMed

    Graham, James E; Wantland, Nicholas B; Campbell, Mark; Klotz, Martin G

    2011-01-01

    Recent advances in DNA sequencing have greatly accelerated our ability to obtain the raw information needed to recognize both known and potential novel modular microbial genomic capacity for nitrogen metabolism. With PCR-based approaches to quantifying microbial mRNA expression now mainstream in most laboratories, researchers can now more efficiently propose and test hypotheses on the contributions of individual microbes to the biological accessibility of nitrogen upon which all other life depends. We review known microbial roles in these key nitrogen transformations, and describe the necessary steps in carrying out relevant gene expression studies. An example experimental design is then provided characterizing Nitrosococcus oceani mRNA expression in cultures responding to ammonia. The approach described, that of assessing microbial genome inventory and testing putative modular gene expression by mRNA quantification, is likely to remain an important tool in understanding individual microbial contributions within microbial community activities that maintain the Earth's nitrogen balance.

  11. The pleiotropic transcriptional regulator NlpR contributes to the modulation of nitrogen metabolism, lipogenesis and triacylglycerol accumulation in oleaginous rhodococci.

    PubMed

    Hernández, Martín A; Lara, Julia; Gago, Gabriela; Gramajo, Hugo; Alvarez, Héctor M

    2017-01-01

    The regulatory mechanisms involved in lipogenesis and triacylglycerol (TAG) accumulation are largely unknown in oleaginous rhodococci. In this study a regulatory protein (here called NlpR: Nitrogen lipid Regulator), which contributes to the modulation of nitrogen metabolism, lipogenesis and triacylglycerol accumulation in oleaginous rhodococci was identified. Under nitrogen deprivation conditions, in which TAG accumulation is stimulated, the nlpR gene was significantly upregulated, whereas a significant decrease of its expression and TAG accumulation occurred when cerulenin was added. The nlpR disruption negatively affected the nitrate/nitrite reduction as well as lipid biosynthesis under nitrogen-limiting conditions. In contrast, its overexpression increased TAG production during cultivation of cells in nitrogen-rich media. A putative 'NlpR-binding motif' upstream of several genes related to nitrogen and lipid metabolisms was found. The nlpR disruption in RHA1 strain led to a reduced transcription of genes involved in nitrate/nitrite assimilation, as well as in fatty acid and TAG biosynthesis. Purified NlpR was able to bind to narK, nirD, fasI, plsC and atf3 promoter regions. It was suggested that NlpR acts as a pleiotropic transcriptional regulator by activating of nitrate/nitrite assimilation genes and others genes involved in fatty acid and TAG biosynthesis, in response to nitrogen deprivation.

  12. Elevated ozone and nitrogen deposition affect nitrogen pools of subalpine grassland.

    PubMed

    Bassin, Seraina; Käch, David; Valsangiacomo, Alain; Mayer, Jochen; Oberholzer, Hans-Rudolf; Volk, Matthias; Fuhrer, Jürg

    2015-06-01

    In a free-air fumigation experiment with subalpine grassland, we studied long-term effects of elevated ozone (O3) and nitrogen (N) deposition on ecosystem N pools and on the fate of anthropogenic N. At three times during the seventh year of exposure, N pools and recovery of a stable isotope tracer ((15)N) were determined in above- and belowground plant parts, and in the soil. Plants were much better competitors for (15)N than soil microorganisms. Plant N pools increased by 30-40% after N addition, while soil pools remained unaffected, suggesting that most of the extra N was taken up and stored in plant biomass, thus preventing the ecosystem from acquiring characteristics of eutrophication. Elevated O3 caused an increase of N in microbial biomass and in stabilized soil N, probably resulting from increased litter input and lower litter quality. Different from individual effects, the interaction between the pollutants remained partly unexplained.

  13. Effects of nitrogen underfeeding and energy source on nitrogen ruminal metabolism, digestion, and nitrogen partitioning in dairy cows.

    PubMed

    Fanchone, A; Nozière, P; Portelli, J; Duriot, B; Largeau, V; Doreau, M

    2013-02-01

    This work aimed to investigate the effects of 2 levels of N (low or high) and 2 energy sources (starch or fiber) on N partitioning, N ruminal metabolism, and digestion in dairy cows. Four Holstein cows were used in a 4 × 4 Latin square design. The 4 cows (on average, 662 ± 62 kg and at 71 ± 10 d in milk at the beginning of the experiment) were fitted with rumen, proximal duodenum, and terminal ileum cannula. The cows received 4 diets having the same forage proportion on a DM basis. The high level of N supply met 110% of the protein requirements of cows with an adequate supply in rumen-degradable N. The low level covered 80% of these requirements with a shortage in rumen-degradable N. Energy sources differed by their nature (i.e., starch from barley, corn, and wheat or fiber from soybean hulls and dehydrated beet pulp). Duodenal digesta flow was determined using YbCl3 as a marker. Microbial duodenal N flow was determined using purine and pyrimidine bases as markers from liquid-associated bacteria and mixed bacteria samples. Microbial N flow and efficiency of microbial protein synthesis, calculated using mixed bacteria as a reference microbial sample, were not significantly modified by the N level (P = 0.19 and 0.29, respectively) and the energy source of the diet (P = 0.11 and 0.08, respectively). Total tract apparent digestibility of OM and total tact digestibility of NDF were lower at the low N level (P = 0.006 and 0.007, respectively). Total tract apparent digestibility of OM tended to be greater (P = 0.08) with high-starch diets than with high-fiber diets. Total tact digestibility of NDF was greater (P < 0.001) with high-fiber diets than with high-starch diets. Duodenal N flow was less (P = 0.001) at the low N level than high N level and tended to be greater (P = 0.06) with high-starch diets than with high-fiber diets. Daily output of N in urine was less (P < 0.001) at the low N level than at the high N level. Daily output of N in feces did not differ between

  14. How inhibiting nitrification affects nitrogen cycle and reduces environmental impacts of anthropogenic nitrogen input

    EPA Science Inventory

    We conducted a meta-analysis of 103 nitrification inhibitor (NI) studies, and evaluated how NI application affects crop productivity and other ecosystem services in agricultural systems. Our results showed that, compared to conventional fertilizer practice, applications of NI alo...

  15. Impact of chronic renal failure on nitrogen metabolism.

    PubMed

    Maroni, B J

    1998-01-01

    Evidence indicates that both nephrotic and nonnephrotic chronic renal failure (CRF) patients can activate normal compensatory responses when dietary protein intake is restricted and that their protein and energy requirements are similar to normal subjects. When properly implemented, low-protein diets are safe and the benefits include the amelioration of uremic symptoms and some of their metabolic complications and possibly a reduction in the rate of progression of renal failure. To ensure dietary adequacy and compliance, patients should be monitored when treated with low-protein diets. Recent evidence that the protein intake of patients with progressive CRF declines when they consume unrestricted diets should not be considered as an argument against the use of low-protein diets. Rather, it is a persuasive argument in favor of restricting dietary protein intake to minimize the complications of renal failure.

  16. The Choice of Euthanasia Method Affects Metabolic Serum Biomarkers.

    PubMed

    Paula, Pierozan; Fredrik, Jernerén; Yusuf, Ransome; Oskar, Karlsson

    2017-02-28

    The impact of euthanasia methods on endocrine and metabolic parameters in rodent tissues and biological fluids is highly relevant for the accuracy and reliability of the data collected. However, few studies concerning this issue are found in the literature. We compared the effects of three euthanasia methods currently used in animal experimentation (i.e. decapitation, CO2 inhalation, and pentobarbital injection) on the serum levels of corticosterone, insulin, glucose, triglycerides, cholesterol and a range of free fatty acids in rats. The corticosterone and insulin levels were not significantly affected by the euthanasia protocol used. However, euthanasia by an overdose of pentobarbital (120 mg/kg intraperitoneal injection) increased the serum levels of glucose, and decreased cholesterol, stearic and arachidonic acids levels compared with euthanasia by CO2 inhalation and decapitation. CO2 inhalation appears to increase the serum levels of triglycerides, while euthanasia by decapitation induced no individual discrepant biomarker level. We conclude that choice of the euthanasia methods are critical for the reliability of serum biomarkers and indicate the importance of selecting adequate euthanasia methods for metabolic analysis in rodents. Decapitation without anaesthesia may be the most adequate method of euthanasia when taking both animal welfare and data quality in consideration. This article is protected by copyright. All rights reserved.

  17. Foliar δ15N is affected by foliar nitrogen uptake, soil nitrogen, and mycorrhizae along a nitrogen deposition gradient.

    PubMed

    Vallano, Dena M; Sparks, Jed P

    2013-05-01

    Foliar nitrogen isotope (δ(15)N) composition patterns have been linked to soil N, mycorrhizal fractionation, and within-plant fractionations. However, few studies have examined the potential importance of the direct foliar uptake of gaseous reactive N on foliar δ(15)N. Using an experimental set-up in which the rate of mycorrhizal infection was reduced using a fungicide, we examined the influence of mycorrhizae on foliar δ(15)N in potted red maple (Acer rubrum) seedlings along a regional N deposition gradient in New York State. Mycorrhizal associations altered foliar δ(15)N values in red maple seedlings from 0.06 to 0.74 ‰ across sites. At the same sites, we explored the predictive roles of direct foliar N uptake, soil δ(15)N, and mycorrhizae on foliar δ(15)N in adult stands of A. rubrum, American beech (Fagus grandifolia), black birch (Betula lenta), and red oak (Quercus rubra). Multiple regression analysis indicated that ambient atmospheric nitrogen dioxide (NO2) concentration explained 0, 69, 23, and 45 % of the variation in foliar δ(15)N in American beech, red maple, red oak, and black birch, respectively, after accounting for the influence of soil δ(15)N. There was no correlation between foliar δ(13)C and foliar %N with increasing atmospheric NO2 concentration in most species. Our findings suggest that total canopy uptake, and likely direct foliar N uptake, of pollution-derived atmospheric N deposition may significantly impact foliar δ(15)N in several dominant species occurring in temperate forest ecosystems.

  18. Effects of nitrogen metabolism on growth and aflatoxin biosynthesis in Aspergillus flavus.

    PubMed

    Wang, Bin; Han, Xiaoyun; Bai, Youhuang; Lin, Zhenguo; Qiu, Mengguang; Nie, Xinyi; Wang, Sen; Zhang, Feng; Zhuang, Zhenhong; Yuan, Jun; Wang, Shihua

    2017-02-15

    Aflatoxins (AFs), produced mainly by Aspergillus flavus and Aspergillus parasiticus, are strongly toxic and carcinogenic. Here, we showed that glutamine is the optimal nitrogen source for AF-production in A. flavus grown in Czapek Dox medium. Additionally, 4mM glutamine was the threshold for high production of aflatoxin B1. However, no significant impact of glutamine synthetase inhibitor was detected for on AF biosynthesis. In contrast, rapamycin could significantly suppress the glutamine inducing effect on AFs production, simultaneously inhibiting the fungal growth and conidiation. To identify the genes and regulatory networks involved in AFs biosynthesis, especially concerning the nitrogen source metabolism pathway and the target of rapamycin (TOR) signaling pathway, we obtained transcriptomes for A. flavus under treatment of three nitrogen sources by RNA-sequencing. We identified 1429 differentially expressed genes. Through GO and KEGG pathway analyses, the relationship between nitrogen metabolism and AFs biosynthesis was revealed, and the effects of TOR inhibitor were confirmed. Additionally, the quantitative real-time PCR results verified the credibility and reliability of the RNA-seq data, and were consistent with the other experimental results. Our research laid the foundation for a primary study on the involvement of the nitrogen regulatory network and TOR signaling pathway in AF biosynthesis.

  19. Nitrogen deficiency in barley (Hordeum vulgare) seedlings induces molecular and metabolic adjustments that trigger aphid resistance.

    PubMed

    Comadira, Gloria; Rasool, Brwa; Karpinska, Barbara; Morris, Jenny; Verrall, Susan R; Hedley, Peter E; Foyer, Christine H; Hancock, Robert D

    2015-06-01

    Agricultural nitrous oxide (N2O) pollution resulting from the use of synthetic fertilizers represents a significant contribution to anthropogenic greenhouse gas emissions, providing a rationale for reduced use of nitrogen (N) fertilizers. Nitrogen limitation results in extensive systems rebalancing that remodels metabolism and defence processes. To analyse the regulation underpinning these responses, barley (Horedeum vulgare) seedlings were grown for 7 d under N-deficient conditions until net photosynthesis was 50% lower than in N-replete controls. Although shoot growth was decreased there was no evidence for the induction of oxidative stress despite lower total concentrations of N-containing antioxidants. Nitrogen-deficient barley leaves were rich in amino acids, sugars and tricarboxylic acid cycle intermediates. In contrast to N-replete leaves one-day-old nymphs of the green peach aphid (Myzus persicae) failed to reach adulthood when transferred to N-deficient barley leaves. Transcripts encoding cell, sugar and nutrient signalling, protein degradation and secondary metabolism were over-represented in N-deficient leaves while those associated with hormone metabolism were similar under both nutrient regimes with the exception of mRNAs encoding proteins involved in auxin metabolism and responses. Significant similarities were observed between the N-limited barley leaf transcriptome and that of aphid-infested Arabidopsis leaves. These findings not only highlight significant similarities between biotic and abiotic stress signalling cascades but also identify potential targets for increasing aphid resistance with implications for the development of sustainable agriculture.

  20. Nitrogen deficiency in barley (Hordeum vulgare) seedlings induces molecular and metabolic adjustments that trigger aphid resistance

    PubMed Central

    Comadira, Gloria; Rasool, Brwa; Karpinska, Barbara; Morris, Jenny; Verrall, Susan R.; Hedley, Peter E.; Foyer, Christine H.; Hancock, Robert D.

    2015-01-01

    Agricultural nitrous oxide (N2O) pollution resulting from the use of synthetic fertilizers represents a significant contribution to anthropogenic greenhouse gas emissions, providing a rationale for reduced use of nitrogen (N) fertilizers. Nitrogen limitation results in extensive systems rebalancing that remodels metabolism and defence processes. To analyse the regulation underpinning these responses, barley (Horedeum vulgare) seedlings were grown for 7 d under N-deficient conditions until net photosynthesis was 50% lower than in N-replete controls. Although shoot growth was decreased there was no evidence for the induction of oxidative stress despite lower total concentrations of N-containing antioxidants. Nitrogen-deficient barley leaves were rich in amino acids, sugars and tricarboxylic acid cycle intermediates. In contrast to N-replete leaves one-day-old nymphs of the green peach aphid (Myzus persicae) failed to reach adulthood when transferred to N-deficient barley leaves. Transcripts encoding cell, sugar and nutrient signalling, protein degradation and secondary metabolism were over-represented in N-deficient leaves while those associated with hormone metabolism were similar under both nutrient regimes with the exception of mRNAs encoding proteins involved in auxin metabolism and responses. Significant similarities were observed between the N-limited barley leaf transcriptome and that of aphid-infested Arabidopsis leaves. These findings not only highlight significant similarities between biotic and abiotic stress signalling cascades but also identify potential targets for increasing aphid resistance with implications for the development of sustainable agriculture. PMID:26038307

  1. Maternal metabolic stress may affect oviduct gatekeeper function.

    PubMed

    Jordaens, Lies; Van Hoeck, Veerle; Maillo, Veronica; Gutierrez-Adan, Alfonso; Marei, Waleed Fawzy A; Vlaeminck, Bruno; Thys, Sofie; Sturmey, Roger G S; Bols, Peter; Leroy, Jo

    2017-03-03

    We hypothesized that elevated non-esterified fatty acids (NEFA) modify in vitro bovine oviduct epithelial cell (BOEC) metabolism and barrier function. Hereto, BOECs were studied in a polarized system with 24h-treatments at day 9: 1) CONTROL (0µM NEFA + 0%EtOH), 2) SOLVENT CONTROL (0µM NEFA + 0.45%EtOH), 3) BASAL NEFA (720µM NEFA + 0.45%EtOH in the basal compartment), 4) APICAL NEFA (720µM NEFA + 0.45%EtOH in the apical compartment). FITC-albumin was used for monolayer permeability assessment, and related to Transepithelial Electric Resistance (TER). Fatty acid (FA), glucose, lactate and pyruvate concentrations were measured in spent medium. Intracellular lipid droplets (LD) and FA-uptake were studied using Bodipy 493/503 and immunolabelling of FA-transporters (FAT/CD36, FABP3 and caveolin1). BOEC-mRNA was retrieved for qRT-PCR. Results revealed that APICAL NEFA reduced relative TER-increase (46.85%) during treatment, and increased FITC-albumin flux (27.59%) compared to other treatments. In BASAL NEFA, FAs were transferred to the apical compartment as free FAs: mostly palmitic and oleic acid increased, respectively 56.0 % and 33.5% of initial FA-concentrations. APICAL NEFA allowed no FA-transfer, but induced LD-accumulation and upregulated FA-transporter expression (↑CD36, ↑FABP3, ↑CAV1-protein-expression). Gene expression in APICAL NEFA indicated increased anti-apoptotic (↑BCL2) and anti-oxidative (↑SOD1) capacity, upregulated lipid metabolism (↑CPT1, ↑ACSL1 and ↓ACACA), and FA-uptake (↑CAV1). All treatments had similar carbohydrate metabolism and oviduct function specific gene expression (=OVGP1, ESR1, FOXJ1). Overall, elevated NEFAs affected BOEC-metabolism and barrier function differently depending on NEFA-exposure side. Data substantiate the concept of the oviduct as a gatekeeper that may actively alter early embryonic developmental conditions.

  2. Evolutionary Convergence and Nitrogen Metabolism in Blattabacterium strain Bge, Primary Endosymbiont of the Cockroach Blattella germanica

    PubMed Central

    López-Sánchez, Maria J.; Neef, Alexander; Peretó, Juli; Patiño-Navarrete, Rafael; Pignatelli, Miguel; Latorre, Amparo; Moya, Andrés

    2009-01-01

    Bacterial endosymbionts of insects play a central role in upgrading the diet of their hosts. In certain cases, such as aphids and tsetse flies, endosymbionts complement the metabolic capacity of hosts living on nutrient-deficient diets, while the bacteria harbored by omnivorous carpenter ants are involved in nitrogen recycling. In this study, we describe the genome sequence and inferred metabolism of Blattabacterium strain Bge, the primary Flavobacteria endosymbiont of the omnivorous German cockroach Blattella germanica. Through comparative genomics with other insect endosymbionts and free-living Flavobacteria we reveal that Blattabacterium strain Bge shares the same distribution of functional gene categories only with Blochmannia strains, the primary Gamma-Proteobacteria endosymbiont of carpenter ants. This is a remarkable example of evolutionary convergence during the symbiotic process, involving very distant phylogenetic bacterial taxa within hosts feeding on similar diets. Despite this similarity, different nitrogen economy strategies have emerged in each case. Both bacterial endosymbionts code for urease but display different metabolic functions: Blochmannia strains produce ammonia from dietary urea and then use it as a source of nitrogen, whereas Blattabacterium strain Bge codes for the complete urea cycle that, in combination with urease, produces ammonia as an end product. Not only does the cockroach endosymbiont play an essential role in nutrient supply to the host, but also in the catabolic use of amino acids and nitrogen excretion, as strongly suggested by the stoichiometric analysis of the inferred metabolic network. Here, we explain the metabolic reasons underlying the enigmatic return of cockroaches to the ancestral ammonotelic state. PMID:19911043

  3. Neurochemistry of Pressure-Induced Nitrogen and Metabolically Inert Gas Narcosis in the Central Nervous System.

    PubMed

    Rostain, Jean-Claude; Lavoute, Cécile

    2016-06-13

    Gases that are not metabolized by the organism are thus chemically inactive under normal conditions. Such gases include the "noble gases" of the Periodic Table as well as hydrogen and nitrogen. At increasing pressure, nitrogen induces narcosis at 4 absolute atmospheres (ATAs) and more in humans and at 11 ATA and more in rats. Electrophysiological and neuropharmacological studies suggest that the striatum is a target of nitrogen narcosis. Glutamate and dopamine release from the striatum in rats are decreased by exposure to nitrogen at a pressure of 31 ATA (75% of the anesthetic threshold). Striatal dopamine levels decrease during exposure to compressed argon, an inert gas more narcotic than nitrogen, or to nitrous oxide, an anesthetic gas. Inversely, striatal dopamine levels increase during exposure to compressed helium, an inert gas with a very low narcotic potency. Exposure to nitrogen at high pressure does not change N-methyl-d-aspartate (NMDA) glutamate receptor activities in Substantia Nigra compacta and striatum but enhances gama amino butyric acidA (GABAA) receptor activities in Substantia Nigra compacta. The decrease in striatal dopamine levels in response to hyperbaric nitrogen exposure is suppressed by recurrent exposure to nitrogen narcosis, and dopamine levels increase after four or five exposures. This change, the lack of improvement of motor disturbances, the desensitization of GABAA receptors on dopamine cells during recurrent exposures and the long-lasting decrease of glutamate coupled with the higher sensitivity of NMDA receptors, suggest a nitrogen toxicity induced by repetitive exposures to narcosis. These differential changes in different neurotransmitter receptors would support the binding protein theory. © 2016 American Physiological Society. Compr Physiol 6:1579-1590, 2016.

  4. Nitrogen fertilizer and gender effects on the secondary metabolism of yaupon, a caffeine-containing North American holly.

    PubMed

    Palumbo, Matthew J; Putz, Francis E; Talcott, Stephen T

    2007-02-01

    Yaupon (Ilex vomitoria) is a caffeine-containing dioecious shrub native to the southeastern United States that was historically brewed into a stimulating beverage. We tested predictions of the carbon/nutrient balance (CNB) hypothesis by determining whether nitrogen availability and gender influence production of caffeine and related alkaloids as well as phenolic compounds in leaves of pot-grown yaupon plants fertilized with ammonium nitrate. The CNB hypothesis predicts that additional nitrogen should result in increased alkaloid concentrations and decreased phenolic concentrations. An extension of the CNB hypothesis to dioecious plants predicts that females have higher C/N ratios and therefore higher phenolic concentrations and lower alkaloid concentrations than male conspecifics. In our study, caffeine and total alkaloid concentrations were 5-10 times higher in fertilized than control plants but did not vary by gender. Nevertheless, an observed interaction between gender and fertilization suggests that females respond more to fertilization than males in caffeine production. In addition, fertilized plants not only contained higher concentrations of alkaloids and total nitrogen but also allocated a larger proportion of their nitrogen to alkaloid production than control plants. Total phenolic concentrations were higher in control females than control males as predicted by the CNB hypothesis, but did not vary by treatment nor were there differences by gender among fertilized plants. We also found high correlations between antioxidant capacity and both classes of phenolic compounds detected in our study (cinnamic acid derivatives and flavonoids) indicating that in addition to their putative defensive function against herbivores, phenolics protect yaupon from oxidative stress. Explanation of the inconsistencies between our data and predictions of the CNB hypothesis may benefit from a re-appraisal of the physiological mechanisms by which resource availability affects

  5. Plant water use affects competition for nitrogen: why drought favors invasive species in California.

    PubMed

    Everard, Katherine; Seabloom, Eric W; Harpole, W Stanley; de Mazancourt, Claire

    2010-01-01

    Abstract: Classic resource competition theory typically treats resource supply rates as independent; however, nutrient supplies can be affected by plants indirectly, with important consequences for model predictions. We demonstrate this general phenomenon by using a model in which competition for nitrogen is mediated by soil moisture, with competitive outcomes including coexistence and multiple stable states as well as competitive exclusion. In the model, soil moisture regulates nitrogen availability through soil moisture dependence of microbial processes, leaching, and plant uptake. By affecting water availability, plants also indirectly affect nitrogen availability and may therefore alter the competitive outcome. Exotic annual species from the Mediterranean have displaced much of the native perennial grasses in California. Nitrogen and water have been shown to be potentially limiting in this system. We parameterize the model for a Californian grassland and show that soil moisture-mediated competition for nitrogen can explain the annual species' dominance in drier areas, with coexistence expected in wetter regions. These results are concordant with larger biogeographic patterns of grassland invasion in the Pacific states of the United States, in which annual grasses have invaded most of the hot, dry grasslands in California but perennial grasses dominate the moister prairies of northern California, Oregon, and Washington.

  6. Nitrogen stress affects the turnover and size of nitrogen pools supplying leaf growth in a grass.

    PubMed

    Lehmeier, Christoph Andreas; Wild, Melanie; Schnyder, Hans

    2013-08-01

    The effect of nitrogen (N) stress on the pool system supplying currently assimilated and (re)mobilized N for leaf growth of a grass was explored by dynamic ¹⁵N labeling, assessment of total and labeled N import into leaf growth zones, and compartmental analysis of the label import data. Perennial ryegrass (Lolium perenne) plants, grown with low or high levels of N fertilization, were labeled with ¹⁵NO₃⁻/¹⁴NO₃⁻ from 2 h to more than 20 d. In both treatments, the tracer time course in N imported into the growth zones fitted a two-pool model (r² > 0.99). This consisted of a "substrate pool," which received N from current uptake and supplied the growth zone, and a recycling/mobilizing "store," which exchanged with the substrate pool. N deficiency halved the leaf elongation rate, decreased N import into the growth zone, lengthened the delay between tracer uptake and its arrival in the growth zone (2.2 h versus 0.9 h), slowed the turnover of the substrate pool (half-life of 3.2 h versus 0.6 h), and increased its size (12.4 μg versus 5.9 μg). The store contained the equivalent of approximately 10 times (low N) and approximately five times (high N) the total daily N import into the growth zone. Its turnover agreed with that of protein turnover. Remarkably, the relative contribution of mobilization to leaf growth was large and similar (approximately 45%) in both treatments. We conclude that turnover and size of the substrate pool are related to the sink strength of the growth zone, whereas the contribution of the store is influenced by partitioning between sinks.

  7. Nitrogen metabolism of two contrasting poplar species during acclimation to limiting nitrogen availability.

    PubMed

    Luo, Jie; Li, Hong; Liu, Tongxian; Polle, Andrea; Peng, Changhui; Luo, Zhi-Bin

    2013-11-01

    To investigate N metabolism of two contrasting Populus species in acclimation to low N availability, saplings of slow-growing species (Populus popularis, Pp) and a fast-growing species (Populus alba × Populus glandulosa, Pg) were exposed to 10, 100, or 1000 μM NH4NO3. Despite greater root biomass and fine root surface area in Pp, lower net influxes of NH4(+) and NO3(-) at the root surface were detected in Pp compared to those in Pg, corresponding well to lower NH4(+) and NO3(-) content and total N concentration in Pp roots. Meanwhile, higher stable N isotope composition (δ(15)N) in roots and stronger responsiveness of transcriptional regulation of 18 genes involved in N metabolism were found in roots and leaves of Pp compared to those of Pg. These results indicate that the N metabolism of Pp is more sensitive to decreasing N availability than that of Pg. In both species, low N treatments decreased net influxes of NH4(+) and NO3(-), root NH4(+) and foliar NO3(-) content, root NR activities, total N concentration in roots and leaves, and transcript levels of most ammonium (AMTs) and nitrate (NRTs) transporter genes in leaves and genes involved in N assimilation in roots and leaves. Low N availability increased fine root surface area, foliar starch concentration, δ(15)N in roots and leaves, and transcript abundance of several AMTs (e.g. AMT1;2) and NRTs (e.g. NRT1;2 and NRT2;4B) in roots of both species. These data indicate that poplar species slow down processes of N acquisition and assimilation in acclimation to limiting N supply.

  8. Nitrogen fixation and metabolism by groundwater-dependent perennial plants in a hyperarid desert.

    PubMed

    Arndt, Stefan K; Kahmen, Ansgar; Arampatsis, Christina; Popp, Marianne; Adams, Mark

    2004-11-01

    The Central Asian Taklamakan desert is characterized by a hyperarid climate with less than 50 mm annual precipitation but a permanent shallow groundwater table. The perched groundwater (2-16 m) could present a reliable and constant source of nitrogen throughout the growing season and help overcome temporal nitrogen limitations that are common in arid environments. We investigated the importance of groundwater and nitrogen fixation in the nitrogen metabolism of desert plants by assessing the possible forms and availability of soil N and atmospheric N and the seasonal variation in concentration as well as isotopic composition of plant N. Water availability was experimentally modified in the desert foreland through simulated flooding to estimate the contribution of surface water and temporally increased soil moisture for nutrient uptake and plant-water relations. The natural vegetation of the Taklamakan desert is dominated by plants with high foliar nitrogen concentrations (2-3% DM) and leaf nitrate reductase activity (NRA) (0.2-1 micromol NO2- g(-1) FW h(-1)). There is little evidence that nitrogen is a limiting resource as all perennial plants exhibited fast rates of growth. The extremely dry soil conditions preclude all but minor contributions of soil N to total plant N so that groundwater is suggested as the dominant source of N with concentrations of 100 microM NO3-. Flood irrigation had little beneficial effect on nitrogen metabolism and growth, further confirming the dependence on groundwater. Nitrogen fixation was determined by the 15N natural abundance method and was a significant component of the N-requirement of the legume Alhagi, the average contribution of biologically fixed nitrogen in Alhagi was 54.8%. But nitrogen fixing plants had little ecological advantage owing to the more or less constant supply of N available from groundwater. From our data we conclude that the perennial species investigated have adapted to the environmental conditions through

  9. Metabolic streamlining in an open-ocean nitrogen-fixing cyanobacterium.

    PubMed

    Tripp, H James; Bench, Shellie R; Turk, Kendra A; Foster, Rachel A; Desany, Brian A; Niazi, Faheem; Affourtit, Jason P; Zehr, Jonathan P

    2010-03-04

    Nitrogen (N(2))-fixing marine cyanobacteria are an important source of fixed inorganic nitrogen that supports oceanic primary productivity and carbon dioxide removal from the atmosphere. A globally distributed, periodically abundant N(2)-fixing marine cyanobacterium, UCYN-A, was recently found to lack the oxygen-producing photosystem II complex of the photosynthetic apparatus, indicating a novel metabolism, but remains uncultivated. Here we show, from metabolic reconstructions inferred from the assembly of the complete UCYN-A genome using massively parallel pyrosequencing of paired-end reads, that UCYN-A has a photofermentative metabolism and is dependent on other organisms for essential compounds. We found that UCYN-A lacks a number of major metabolic pathways including the tricarboxylic acid cycle, but retains sufficient electron transport capacity to generate energy and reducing power from light. Unexpectedly, UCYN-A has a reduced genome (1.44 megabases) that is structurally similar to many chloroplasts and some bacteria, in that it contains inverted repeats of ribosomal RNA operons. The lack of biosynthetic pathways for several amino acids and purines suggests that this organism depends on other organisms, either in close association or in symbiosis, for critical nutrients. However, size fractionation experiments using natural populations have so far not provided evidence of a symbiotic association with another microorganism. The UCYN-A cyanobacterium is a paradox in evolution and adaptation to the marine environment, and is an example of the tight metabolic coupling between microorganisms in oligotrophic oceanic microbial communities.

  10. Plastidial metabolite transporters integrate photorespiration with carbon, nitrogen, and sulfur metabolism.

    PubMed

    Eisenhut, Marion; Hocken, Nadine; Weber, Andreas P M

    2015-07-01

    Plant photorespiration is an essential prerequisite for oxygenic photosynthesis. This metabolic repair pathway bestrides four compartments, which poses the requirement for several metabolites transporters for pathway function. However, in contrast to the well-studied enzymatic steps of the core photorespiratory cycle, only few photorespiratory translocators have been identified to date. In this review, we give an overview of established and unknown plastidic transport proteins involved in photorespiration and intertwined nitrogen and sulfur metabolism, respectively. Furthermore, we discuss the evolutionary origin of the dicarboxylate translocators and the recently identified glycolate glycerate translocator.

  11. An ecological and evolutionary context for integrated nitrogen metabolism and related signaling pathways in marine diatoms.

    PubMed

    Allen, Andrew E; Vardi, Assaf; Bowler, Chris

    2006-06-01

    Whole-genome sequence analysis has revealed that diatoms contain genes and pathways that are novel in photosynthetic eukaryotes. More generally, the unique evolutionary footprint of the chromalveolates, which includes a genome fusion between a heterotrophic protist and a red alga in addition to a major prokaryotic influence, has fostered their inheritance of a unique complement of metabolic capabilities. Many aspects of nitrogen metabolism and cell signaling appear to be linked in diatoms. This new perspective provides a basis for understanding the ecological dominance of diatoms in contemporary oceans.

  12. Multiple dietary supplements do not affect metabolic and cardiovascular health

    PubMed Central

    Holloszy, John O.; Fontana, Luigi

    2014-01-01

    Dietary supplements are widely used for health purposes. However, little is known about the metabolic and cardiovascular effects of combinations of popular over-the-counter supplements, each of which has been shown to have anti-oxidant, anti-inflammatory and pro-longevity properties in cell culture or animal studies. This study was a 6-month randomized, single-blind controlled trial, in which 56 non-obese (BMI 21.0-29.9 kg/m2) men and women, aged 38 to 55 yr, were assigned to a dietary supplement (SUP) group or control (CON) group, with a 6-month follow-up. The SUP group took 10 dietary supplements each day (100 mg of resveratrol, a complex of 800 mg each of green, black, and white tea extract, 250 mg of pomegranate extract, 650 mg of quercetin, 500 mg of acetyl-l-carnitine, 600 mg of lipoic acid, 900 mg of curcumin, 1 g of sesamin, 1.7 g of cinnamon bark extract, and 1.0 g fish oil). Both the SUP and CON groups took a daily multivitamin/mineral supplement. The main outcome measures were arterial stiffness, endothelial function, biomarkers of inflammation and oxidative stress, and cardiometabolic risk factors. Twenty-four weeks of daily supplementation with 10 dietary supplements did not affect arterial stiffness or endothelial function in nonobese individuals. These compounds also did not alter body fat measured by DEXA, blood pressure, plasma lipids, glucose, insulin, IGF-1, and markers of inflammation and oxidative stress. In summary, supplementation with a combination of popular dietary supplements has no cardiovascular or metabolic effects in non-obese relatively healthy individuals. PMID:24659610

  13. Deciphering the Role of Aspartate and Prephenate Aminotransferase Activities in Plastid Nitrogen Metabolism1[C][W][OPEN

    PubMed Central

    de la Torre, Fernando; El-Azaz, Jorge; Ávila, Concepción; Cánovas, Francisco M.

    2014-01-01

    Chloroplasts and plastids of nonphotosynthetic plant cells contain two aspartate (Asp) aminotransferases: a eukaryotic type (Asp5) and a prokaryotic-type bifunctional enzyme displaying Asp and prephenate aminotransferase activities (PAT). We have identified the entire Asp aminotransferase gene family in Nicotiana benthamiana and isolated and cloned the genes encoding the isoenzymes with plastidic localization: NbAsp5 and NbPAT. Using a virus-induced gene silencing approach, we obtained N. benthamiana plants silenced for NbAsp5 and/or NbPAT. Phenotypic and metabolic analyses were conducted in silenced plants to investigate the specific roles of these enzymes in the biosynthesis of essential amino acids within the plastid. The NbAsp5 silenced plants had no changes in phenotype, exhibiting similar levels of free Asp and glutamate as control plants, but contained diminished levels of asparagine and much higher levels of lysine. In contrast, the suppression of NbPAT led to a severe reduction in growth and strong chlorosis symptoms. NbPAT silenced plants exhibited extremely reduced levels of asparagine and were greatly affected in their phenylalanine metabolism and lignin deposition. Furthermore, NbPAT suppression triggered a transcriptional reprogramming in plastid nitrogen metabolism. Taken together, our results indicate that NbPAT has an overlapping role with NbAsp5 in the biosynthesis of Asp and a key role in the production of phenylalanine for the biosynthesis of phenylpropanoids. The analysis of NbAsp5/NbPAT cosilenced plants highlights the central role of both plastidic aminotransferases in nitrogen metabolism; however, only NbPAT is essential for plant growth and development. PMID:24296073

  14. Effects of Lys and His supplementations on the regulation of nitrogen metabolism in lager yeast.

    PubMed

    Lei, Hongjie; Li, Huipin; Mo, Fen; Zheng, Liye; Zhao, Haifeng; Zhao, Mouming

    2013-10-01

    Significant positive correlations between wort fermentability and the assimilation of Lys and His under normal-gravity and high-gravity conditions indicated that Lys and His were the key amino acids for lager yeast during beer brewing. In order to obtain insight into the roles of Lys and His in nitrogen regulation, the influences of Lys, His and their mixture supplementations on the fermentation performance and nitrogen metabolism in lager yeast during high-gravity fermentation were further investigated in the present study. Results showed that Lys and His supplementations improved yeast growth, wort fermentability, ethanol yield and the formation of flavor volatiles. Lys supplementation up-regulated Ssy1p-Ptr3p-Ssy5p (SPS)-regulated genes (LYP1, HIP1, BAP2 and AGP1) dramatically compared to nitrogen catabolite repression (NCR)-sensitive genes (GAP1 and MEP2), whereas His supplementation activated SPS-regulated genes slightly in exponential phase, and repressed NCR-sensitive genes significantly throughout the fermentation. Lys and His supplementations increased the consumption of Glu and Phe, and decreased the consumption of Ser, Trp and Arg. Moreover, Lys and His supplementations exhibited similar effects on the fermentation performance, and were more effective than their mixture supplementation when the same dose was kept. These results demonstrate that both Lys and His are important amino acids for yeast nitrogen metabolism and fermentation performance.

  15. Sirtuin-dependent reversible lysine acetylation of glutamine synthetases reveals an autofeedback loop in nitrogen metabolism

    PubMed Central

    You, Di; Yin, Bin-Cheng; Li, Zhi-Hai; Zhou, Ying; Yu, Wen-Bang; Zuo, Peng; Ye, Bang-Ce

    2016-01-01

    In cells of all domains of life, reversible lysine acetylation modulates the function of proteins involved in central cellular processes such as metabolism. In this study, we demonstrate that the nitrogen regulator GlnR of the actinomycete Saccharopolyspora erythraea directly regulates transcription of the acuA gene (SACE_5148), which encodes a Gcn5-type lysine acetyltransferase. We found that AcuA acetylates two glutamine synthetases (GlnA1 and GlnA4) and that this lysine acetylation inactivated GlnA4 (GSII) but had no significant effect on GlnA1 (GSI-β) activity under the conditions tested. Instead, acetylation of GlnA1 led to a gain-of-function that modulated its interaction with the GlnR regulator and enhanced GlnR–DNA binding. It was observed that this regulatory function of acetylated GSI-β enzymes is highly conserved across actinomycetes. In turn, GlnR controls the catalytic and regulatory activities (intracellular acetylation levels) of glutamine synthetases at the transcriptional and posttranslational levels, indicating an autofeedback loop that regulates nitrogen metabolism in response to environmental change. Thus, this GlnR-mediated acetylation pathway provides a signaling cascade that acts from nutrient sensing to acetylation of proteins to feedback regulation. This work presents significant new insights at the molecular level into the mechanisms underlying the regulation of protein acetylation and nitrogen metabolism in actinomycetes. PMID:27247389

  16. Protein and Nitrogen Metabolism Changes Following Closed Head Injury or Cardiothoracic Surgery in Pediatric Patients

    PubMed Central

    Hak, Emily B.; Rogers, David A.; Storm, Michael C.; Helms, Richard A.

    2005-01-01

    OBJECTIVE We compared markers of protein metabolism between children who had a controlled injury and an acute traumatic event. Significant protein catabolism occurs after acute severe injury. During surgery the injury is controlled and the degree of subsequent catabolism may be blunted. METHODS This was a prospective, unblinded observational study in 10 children 2 to 12 years old with a closed head injury (CHI) and an admission Physiologic Stability Index of ≥ 10 and in 10 children who underwent elective cardiothoracic surgery (CTS). Nutrient intake, nitrogen balance, serum albumin and prealbumin, urinary 3-methylhistidine excretion, and 3-methylhistidine to creatinine ratios were evaluated on days 1, 2, 3, 4, and 10 after injury. RESULTS Nutrient intake was similar in both groups on study days 1–4 and did not meet estimated needs. By day 10, 7 patients in the CTS group and 2 patients in the CHI group had been discharged home. The 3 CTS patients were still in the ICU while the 8 hospitalized CHI patients had been transferred to the floor. Compared to the CTS group, nitrogen balance in the CHI group was lower on day 1. On day 10, nitrogen balance and prealbumin were greater in the CHI group than in the CTS group, consistent with recovery and increased nutrient intake. CONCLUSIONS Markers of protein metabolism follow similar patterns after CTS or CHI in children. However, markers of protein metabolism indicate more severe catabolism soon after injury in CHI. PMID:23118637

  17. Emersion induces nitrogen release and alteration of nitrogen metabolism in the intertidal genus Porphyra.

    PubMed

    Kim, Jang K; Kraemer, George P; Yarish, Charles

    2013-01-01

    We investigated emersion-induced nitrogen (N) release from Porphyra umbilicalis Kütz. Thallus N concentration decreased during 4 h of emersion. Tissue N and soluble protein contents of P. umbilicalis were positively correlated and decreased during emersion. Growth of P. umbilicalis did not simply dilute the pre-emersion tissue N concentration. Rather, N was lost from tissues during emersion. We hypothesize that emersion-induced N release occurs when proteins are catabolized. While the δ(15)N value of tissues exposed to emersion was higher than that of continuously submerged tissues, further discrimination of stable N isotopes did not occur during the 4 h emersion. We conclude that N release from Porphyra during emersion did not result from bacterial denitrification, but possibly as a consequence of photorespiration. The release of N by P. umbilicalis into the environment during emersion suggests a novel role of intertidal seaweeds in the global N cycle. Emersion also altered the physiological function (nitrate uptake, nitrate reductase and glutamine synthetase activity, growth rate) of P. umbilicalis and the co-occurring upper intertidal species P. linearis Grev., though in a seasonally influenced manner. Individuals of the year round perennial species P. umbilicalis were more tolerant of emersion than ephemeral, cold temperate P. linearis in early winter. However, the mid-winter populations of both P. linearis and P. umbilicalis, had similar temporal physiological patterns during emersion.

  18. Photoperiod length paces the temporal orchestration of cell cycle and carbon-nitrogen metabolism in Crocosphaera watsonii.

    PubMed

    Dron, Anthony; Rabouille, Sophie; Claquin, Pascal; Talec, Amélie; Raimbault, Virginie; Sciandra, Antoine

    2013-12-01

    We analysed the effect of photoperiod length (PPL) (16:8 and 8:16 h of light-dark regime, named long and short PPL, respectively) on the temporal orchestration of the two antagonistic, carbon and nitrogen acquisitions in the unicellular, diazotrophic cyanobacterium Crocosphaera watsonii strain WH8501 growing diazotrophically. Carbon and nitrogen metabolism were monitored at high frequency, and their patterns were compared with the cell cycle progression. The oxygen-sensitive N2 fixation process occurred mainly during the dark period, where photosynthesis cannot take place, inducing a light-dark cycle of cellular C : N ratio. Examination of circadian patterns in the cell cycle revealed that cell division occurred during the midlight period, (8 h and 4 h into the light in the long and short PPL conditions, respectively), thus timely separated from the energy-intensive diazotrophic process. Results consistently show a nearly 5 h time lag between the end of cell division and the onset of N2 fixation. Shorter PPLs affected DNA compaction of C. watsonii cells and also led to a decrease in the cell division rate. Therefore, PPL paces the growth of C. watsonii: a long PPL enhances cell division while a short PPL favours somatic growth (biomass production) with higher carbon and nitrogen cell contents.

  19. Nickel Availability in Soil as Influenced by Liming and Its Role in Soybean Nitrogen Metabolism

    PubMed Central

    de Macedo, Fernando G.; Bresolin, Joana D.; Santos, Elcio F.; Furlan, Felipe; Lopes da Silva, Wilson T.; Polacco, Joe C.; Lavres, José

    2016-01-01

    Nickel (Ni) availability in soil varies as a function of pH. Plants require Ni in small quantities for normal development, especially in legumes due its role in nitrogen (N) metabolism. This study investigated the effect of soil base saturation, and Ni amendments on Ni uptake, N accumulation in the leaves and grains, as well as to evaluate organic acids changes in soybean. In addition, two N assimilation enzymes were assayed: nitrate reductase (NR) and Ni-dependent urease. Soybean plants inoculated with Bradyrhizobium japonicum were cultivated in soil-filled pots under two base-cation saturation (BCS) ratios (50 and 70%) and five Ni rates – 0.0; 0.1; 0.5; 1.0; and 10.0 mg dm-3 Ni. At flowering (R1 developmental stage), plants for each condition were evaluated for organic acids (oxalic, malonic, succinic, malic, tartaric, fumaric, oxaloacetic, citric and lactic) levels as well as the activities of urease and NR. At the end of the growth period (R7 developmental stage – grain maturity), grain N and Ni accumulations were determined. The available soil-Ni in rhizosphere extracted by DTPA increased with Ni rates, notably in BCS50. The highest concentrations of organic acid and N occurred in BCS70 and 0.5 mg dm-3 of Ni. There were no significant differences for urease activity taken on plants grown at BSC50 for Ni rates, except for the control treatment, while plants cultivated at soil BCS70 increased the urease activity up to 0.5 mg dm-3 of Ni. In addition, the highest values for urease activities were reached from the 0.5 mg dm-3 of Ni rate for both BCS treatments. The NR activity was not affected by any treatment indicating good biological nitrogen fixation (BNF) for all plants. The reddish color of the nodules increased with Ni rates in both BCS50 and 70, also confirms the good BNF due to Ni availability. The optimal development of soybean occurs in BCS70, but requires an extra Ni supply for the production of organic acids and for increased N-shoot and grain

  20. Regulation of nitrate and methylamine metabolism by multiple nitrogen sources in the methylotrophic yeast Candida boidinii.

    PubMed

    Shiraishi, Kosuke; Oku, Masahide; Uchida, Daichi; Yurimoto, Hiroya; Sakai, Yasuyoshi

    2015-11-01

    The methylotrophic yeast Candida boidinii, which is capable of growth on methanol as a sole carbon source, can proliferate on the leaf surface of Arabidopsis thaliana. Previously, we demonstrated that adaptation to a change in the major available nitrogen source from nitrate to methylamine during the host plant aging was crucial for yeast survival on the leaf environment. In this report, we investigated the regulatory profile of nitrate and methylamine metabolism in the presence of multiple nitrogen sources in C. boidinii. The transcript level of nitrate reductase (Ynr1) gene was induced by nitrate and nitrite, and was not repressed by the coexistence with other nitrogen sources. In contrast, the transcript level of amine oxidase (Amo1) gene, which was induced by methylamine, was significantly repressed by the coexistence with ammonium or glutamine. In addition, we investigated the intracellular dynamics of Ynr1 during the nitrogen source shift from nitrate to other compounds. Under these tested conditions, Ynr1 was effectively transported to the vacuole via selective autophagy only during the shift from nitrate to methylamine. Moreover, Ynr1 was subject to degradation after the shift from nitrate to nitrate plus methylamine medium even though nitrate was still available. These regulatory profiles may reflect life style of nitrogen utilization in this yeast living in the phyllosphere.

  1. Integration of Carbon, Nitrogen, and Oxygen Metabolism in Escherichia coli--Final Report

    SciTech Connect

    Rabinowitz, Joshua D; Wingreen, Ned s; Rabitz, Herschel A; Xu, Yifan

    2012-10-22

    A key challenge for living systems is balancing utilization of multiple elemental nutrients, such as carbon, nitrogen, and oxygen, whose availability is subject to environmental fluctuations. As growth can be limited by the scarcity of any one nutrient, the rate at which each nutrient is assimilated must be sensitive not only to its own availability, but also to that of other nutrients. Remarkably, across diverse nutrient conditions, E. coli grows nearly optimally, balancing effectively the conversion of carbon into energy versus biomass. To investigate the link between the metabolism of different nutrients, we quantified metabolic responses to nutrient perturbations using LC-MS based metabolomics and built differential equation models that bridge multiple nutrient systems. We discovered that the carbonaceous substrate of nitrogen assimilation, -ketoglutarate, directly inhibits glucose uptake and that the upstream glycolytic metabolite, fructose-1,6-bisphosphate, ultrasensitively regulates anaplerosis to allow rapid adaptation to changing carbon availability. We also showed that NADH controls the metabolic response to changing oxygen levels. Our findings support a general mechanism for nutrient integration: limitation for a nutrient other than carbon leads to build-up of the most closely related product of carbon metabolism, which in turn feedback inhibits further carbon uptake.

  2. The Assimilation of Diazotroph-Derived Nitrogen by Scleractinian Corals Depends on Their Metabolic Status.

    PubMed

    Bednarz, Vanessa N; Grover, Renaud; Maguer, Jean-François; Fine, Maoz; Ferrier-Pagès, Christine

    2017-01-10

    Tropical corals are associated with a diverse community of dinitrogen (N2)-fixing prokaryotes (diazotrophs) providing the coral an additional source of bioavailable nitrogen (N) in oligotrophic waters. The overall activity of these diazotrophs changes depending on the current environmental conditions, but to what extent it affects the assimilation of diazotroph-derived N (DDN) by corals is still unknown. Here, in a series of (15)N2 tracer experiments, we directly quantified DDN assimilation by scleractinian corals from the Red Sea exposed to different environmental conditions. We show that DDN assimilation strongly varied with the corals' metabolic status or with phosphate availability in the water. The very autotrophic shallow-water (~5 m) corals showed low or no DDN assimilation, which significantly increased under elevated phosphate availability (3 µM). Corals that depended more on heterotrophy (i.e., bleached and deep-water [~45 m] corals) assimilated significantly more DDN, which contributed up to 15% of the corals' N demand (compared to 1% in shallow corals). Furthermore, we demonstrate that a substantial part of the DDN assimilated by deep corals was likely obtained from heterotrophic feeding on fixed N compounds and/or diazotrophic cells in the mucus. Conversely, in shallow corals, the net release of mucus, rich in organic carbon compounds, likely enhanced diazotroph abundance and activity and thereby the release of fixed N to the pelagic and benthic reef community. Overall, our results suggest that DDN assimilation by corals varies according to the environmental conditions and is likely linked to the capacity of the coral to acquire nutrients from seawater.

  3. The Assimilation of Diazotroph-Derived Nitrogen by Scleractinian Corals Depends on Their Metabolic Status

    PubMed Central

    Grover, Renaud; Maguer, Jean-François; Fine, Maoz; Ferrier-Pagès, Christine

    2017-01-01

    ABSTRACT Tropical corals are associated with a diverse community of dinitrogen (N2)-fixing prokaryotes (diazotrophs) providing the coral an additional source of bioavailable nitrogen (N) in oligotrophic waters. The overall activity of these diazotrophs changes depending on the current environmental conditions, but to what extent it affects the assimilation of diazotroph-derived N (DDN) by corals is still unknown. Here, in a series of 15N2 tracer experiments, we directly quantified DDN assimilation by scleractinian corals from the Red Sea exposed to different environmental conditions. We show that DDN assimilation strongly varied with the corals’ metabolic status or with phosphate availability in the water. The very autotrophic shallow-water (~5 m) corals showed low or no DDN assimilation, which significantly increased under elevated phosphate availability (3 µM). Corals that depended more on heterotrophy (i.e., bleached and deep-water [~45 m] corals) assimilated significantly more DDN, which contributed up to 15% of the corals’ N demand (compared to 1% in shallow corals). Furthermore, we demonstrate that a substantial part of the DDN assimilated by deep corals was likely obtained from heterotrophic feeding on fixed N compounds and/or diazotrophic cells in the mucus. Conversely, in shallow corals, the net release of mucus, rich in organic carbon compounds, likely enhanced diazotroph abundance and activity and thereby the release of fixed N to the pelagic and benthic reef community. Overall, our results suggest that DDN assimilation by corals varies according to the environmental conditions and is likely linked to the capacity of the coral to acquire nutrients from seawater. PMID:28074021

  4. New insight into the strategy for nitrogen metabolism in plant cells.

    PubMed

    Wang, Min; Shen, Qirong; Xu, Guohua; Guo, Shiwei

    2014-01-01

    Nitrogen (N) is one of the most important mineral nutrients required by higher plants. Primary N absorbed by higher plants includes nitrate (NO3(-)), ammonium (NH4(+)), and organic N. Plants have developed several mechanisms for regulating their N metabolism in response to N availability and environmental conditions. Numerous transporters have been characterized and the mode of N movement within plants has been demonstrated. For further assimilation of N, various enzymes are involved in the key processes of NO3(-) or NH4(+) assimilation. N and carbon (C) metabolism are tightly coordinated in the fundamental biochemical pathway that permits plant growth. As N and C metabolism are the fundamental constituents of plant life, understanding N regulation is essential for growing plants and improving crop production. Regulation of N metabolism at the transcriptional and posttranscriptional levels provides important perceptions in the complex regulatory network of plants to adapt to changing N availability. In this chapter, recent advances in elucidating molecular mechanisms of N metabolism processes and regulation strategy, as well as interactions between C and N, are discussed. This review provides new insights into the strategy for studying N metabolism at the cellular level for optimum plant growth in different environments.

  5. A Natural Light/Dark Cycle Regulation of Carbon-Nitrogen Metabolism and Gene Expression in Rice Shoots

    PubMed Central

    Li, Haixing; Liang, Zhijun; Ding, Guangda; Shi, Lei; Xu, Fangsen; Cai, Hongmei

    2016-01-01

    Light and temperature are two particularly important environmental cues for plant survival. Carbon and nitrogen are two essential macronutrients required for plant growth and development, and cellular carbon and nitrogen metabolism must be tightly coordinated. In order to understand how the natural light/dark cycle regulates carbon and nitrogen metabolism in rice plants, we analyzed the photosynthesis, key carbon-nitrogen metabolites, and enzyme activities, and differentially expressed genes and miRNAs involved in the carbon and nitrogen metabolic pathway in rice shoots at the following times: 2:00, 6:00, 10:00, 14:00, 18:00, and 22:00. Our results indicated that more CO2 was fixed into carbohydrates by a high net photosynthetic rate, respiratory rate, and stomatal conductance in the daytime. Although high levels of the nitrate reductase activity, free ammonium and carbohydrates were exhibited in the daytime, the protein synthesis was not significantly facilitated by the light and temperature. In mRNA sequencing, the carbon and nitrogen metabolism-related differentially expressed genes were obtained, which could be divided into eight groups: photosynthesis, TCA cycle, sugar transport, sugar metabolism, nitrogen transport, nitrogen reduction, amino acid metabolism, and nitrogen regulation. Additionally, a total of 78,306 alternative splicing events have been identified, which primarily belong to alternative 5′ donor sites, alternative 3′ acceptor sites, intron retention, and exon skipping. In sRNA sequencing, four carbon and nitrogen metabolism-related miRNAs (osa-miR1440b, osa-miR2876-5p, osa-miR1877 and osa-miR5799) were determined to be regulated by natural light/dark cycle. The expression level analysis showed that the four carbon and nitrogen metabolism-related miRNAs negatively regulated their target genes. These results may provide a good strategy to study how natural light/dark cycle regulates carbon and nitrogen metabolism to ensure plant growth and

  6. [Vertical transporting risk of nitrogen in purple soil affected by surfactant].

    PubMed

    Chen, Yu-cheng; Yang, Zhi-min; Jiang, Ling; Chen, Qing-hu; Gao, Meng

    2010-07-01

    The simulated leaching experiment was conducted to determine the effects of surfactant of sodium dodecyl benzene sulphonate (SDBS) on vertical transporting of nitrogen in purple soil. SDBS could reduce NH4+ -N loss from soil, and the higher concentration of SDBS, the less loss. SDBS could increase NO3- -N loss from soil, and the order of accumulation loss is SDBS100 > SDBS40 > SDBS0 > SDBS5. Lower concentration SDBS decrease TKN loss, but higher concentration SDBS had a reverse effect, and compared with SDBS0, the accumulation loss TKN of SDBS40, SDBS100 increased by 16.8%, 22.36%, respectively. SDBS could affect vertical transporting of nitrogen in purple soil, that is, the significant down-transporting of nitrogen was observed after leaching with SDBS, and the higher concentration of SDBS, the more obviously transporting trend.

  7. Does iodine biofortification affect oxidative metabolism in lettuce plants?

    PubMed

    Blasco, Begoña; Ríos, Juan Jose; Leyva, Rocío; Cervilla, Luis Miguel; Sánchez-Rodríguez, Eva; Rubio-Wilhelmi, María Mar; Rosales, Miguel Angel; Ruiz, Juan Manuel; Romero, Luis

    2011-09-01

    Plants produce low levels of reactive oxygen species (ROS), which form part of basic cell chemical communication; however, different types of stress can lead to an overexpression of ROS that can damage macromolecules essential for plant growth and development. Iodine is vital to human health, and iodine biofortification programs help improve the human intake through plant consumption. This biofortification process has been shown to influence the antioxidant capacity of lettuce plants, suggesting that the oxidative metabolism of the plant may be affected. The results of this study demonstrate that the response to oxidative stress is variable and depends on the form of iodine applied. Application of iodide (I(-)) to lettuce plants produces a reduction in superoxide dismutase (SOD) activity and an increase in catalase (CAT) and L-galactono dehydrogenase enzyme activities and in the activity of antioxidant compounds such as ascorbate (AA) and glutathione. This did not prove a very effective approach since a dose of 80 μM produced a reduction in the biomass of the plants. For its part, application of iodate (IO (3) (-) ) produced an increase in the activities of SOD, ascorbate peroxidase, and CAT, the main enzymes involved in ROS detoxification; it also increased the concentration of AA and the regenerative activities of the Halliwell-Asada cycle. These data confirm the non-phytotoxicity of IO (3) (-) since there is no lipid peroxidation or biomass reduction. According to our results, the ability of IO (3) (-) to induce the antioxidant system indicates that application of this form of iodine may be an effective strategy to improve the response of plants to different types of stress.

  8. Metabolism of reactive oxygen species and reactive nitrogen species in pepper (Capsicum annuum L.) plants under low temperature stress.

    PubMed

    Airaki, Morad; Leterrier, Marina; Mateos, Rosa M; Valderrama, Raquel; Chaki, Mounira; Barroso, Juan B; Del Río, Luis A; Palma, José M; Corpas, Francisco J

    2012-02-01

    Low temperature is an environmental stress that affects crop production and quality and regulates the expression of many genes, and the level of a number of proteins and metabolites. Using leaves from pepper (Capsicum annum L.) plants exposed to low temperature (8 °C) for different time periods (1 to 3 d), several key components of the metabolism of reactive nitrogen and oxygen species (RNS and ROS, respectively) were analysed. After 24 h of exposure at 8 °C, pepper plants exhibited visible symptoms characterized by flaccidity of stems and leaves. This was accompanied by significant changes in the metabolism of RNS and ROS with an increase of both protein tyrosine nitration (NO(2) -Tyr) and lipid peroxidation, indicating that low temperature induces nitrosative and oxidative stress. During the second and third days at low temperature, pepper plants underwent cold acclimation by adjusting their antioxidant metabolism and reverting the observed nitrosative and oxidative stress. In this process, the levels of the soluble non-enzymatic antioxidants ascorbate and glutathione, and the activity of the main NADPH-generating dehydrogenases were significantly induced. This suggests that ascorbate, glutathione and the NADPH-generating dehydrogenases have a role in the process of cold acclimation through their effect on the redox state of the cell.

  9. Relationship between photosynthetic capacity, nitrogen assimilation and nodule metabolism in alfalfa (Medicago sativa) grown with sewage sludge.

    PubMed

    Antolín, M Carmen; Fiasconaro, M Laura; Sánchez-Díaz, Manuel

    2010-10-15

    Sewage sludge has been used as N fertilizer because it contains some of inorganic N, principally as nitrate and ammonium ions. However, sewage sludge addition to legumes could result in impaired nodule metabolism due to the presence of inorganic N from sludge. A greenhouse experiment was conducted to examine the effects of sewage sludge on growth, photosynthesis, nitrogen assimilation and nodule metabolism in alfalfa (Medicago sativa L. cv. Aragón). Plants were grown in pots with a mixture of perlite and vermiculite (2:1, v/v). The experiment included three treatments: (1) plants inoculated with rhizobia and amended with sewage sludge at rate of 10% (w/w) (RS); (2) plants inoculated with rhizobia without any amendment (R); and (3) non-inoculated plants fed with ammonium nitrate (N). N(2)-fixing plants had lower growth and sucrose phosphate synthase activity but higher photosynthesis than nitrate-fed plants because they compensated the carbon cost of the rhizobia. However, sewage sludge-treated plants evidenced a loss of carbon sink strength due to N(2) fixation by means of decreased photosynthetic capacity, leaf chlorophylls and N concentration in comparison to untreated plants. Sewage sludge did no affect nodulation but decreased nodule enzyme activities involved in carbon and N metabolisms that may lead to accumulation of toxic N-compounds.

  10. Sulfite Oxidase Activity Is Essential for Normal Sulfur, Nitrogen and Carbon Metabolism in Tomato Leaves

    PubMed Central

    Brychkova, Galina; Yarmolinsky, Dmitry; Batushansky, Albert; Grishkevich, Vladislav; Khozin-Goldberg, Inna; Fait, Aaron; Amir, Rachel; Fluhr, Robert; Sagi, Moshe

    2015-01-01

    Plant sulfite oxidase [SO; E.C.1.8.3.1] has been shown to be a key player in protecting plants against exogenous toxic sulfite. Recently we showed that SO activity is essential to cope with rising dark-induced endogenous sulfite levels in tomato plants (Lycopersicon esculentum/Solanum lycopersicum Mill. cv. Rheinlands Ruhm). Here we uncover the ramifications of SO impairment on carbon, nitrogen and sulfur (S) metabolites. Current analysis of the wild-type and SO-impaired plants revealed that under controlled conditions, the imbalanced sulfite level resulting from SO impairment conferred a metabolic shift towards elevated reduced S-compounds, namely sulfide, S-amino acids (S-AA), Co-A and acetyl-CoA, followed by non-S-AA, nitrogen and carbon metabolite enhancement, including polar lipids. Exposing plants to dark-induced carbon starvation resulted in a higher degradation of S-compounds, total AA, carbohydrates, polar lipids and total RNA in the mutant plants. Significantly, a failure to balance the carbon backbones was evident in the mutants, indicated by an increase in tricarboxylic acid cycle (TCA) cycle intermediates, whereas a decrease was shown in stressed wild-type plants. These results indicate that the role of SO is not limited to a rescue reaction under elevated sulfite, but SO is a key player in maintaining optimal carbon, nitrogen and sulfur metabolism in tomato plants. PMID:27135342

  11. Nitrogen

    USGS Publications Warehouse

    Apodaca, Lori E.

    2013-01-01

    The article presents an overview of the nitrogen chemical market as of July 2013, including the production of ammonia compounds. Industrial uses for ammonia include fertilizers, explosives, and plastics. Other topics include industrial capacity of U.S. ammonia producers CF Industries Holdings Inc., Koch Nitrogen Co., PCS Nitrogen, Inc., and Agrium Inc., the impact of natural gas prices on the nitrogen industry, and demand for corn crops for ethanol production.

  12. [Effect of ATP and glutaminic acid on carbohydrate-energy and nitrogen metabolism in the rat brain and liver under the effect of pulsed electromagnetic field].

    PubMed

    Mishchenko, L I; Kolodub, F A

    1975-01-01

    Oxidative phosphorylation, content of lactate, creatine phosphate, ammonia and glutamine were studied as affected by ATP and glutaminic acid in the brain and liver of rat subjected to the action of the pulsed electromagnetic field of 7 kHz frequency (72 kA/m, 15 seances). ATP (1 mg per 100 g of weight) was found to have a normalizing effect on the processes of nitrogen metabolism in the rat brain, ATP increasing the intenstiy of the oxidative phosphorylation in the tissues of intact rats, has no analogous influence on the irradiated animals. With administration of glutaminic acid (5 mg per 100 g of weight) the processes of oxidative phosphorylation and nitrogen metabolism, disturbed under the effect of the pulsed electromagnetic field are normalized.

  13. Disruption of MRG19 results in altered nitrogen metabolic status and defective pseudohyphal development in Saccharomyces cerevisiae.

    PubMed

    Das, Maitreyi; Bhat, Paike Jayadeva

    2005-01-01

    It was previously shown that MRG19 downregulates carbon metabolism in Saccharomyces cerevisiae upon glucose exhaustion, and that the gene is glucose repressed. Here, it is shown that glucose repression of MRG19 is overcome upon nitrogen withdrawal, suggesting that MRG19 is a regulator of carbon and nitrogen metabolism. beta-Galactosidase activity fostered by the promoter of GDH1/3, which encode anabolic enzymes of nitrogen metabolism, was altered in an MRG19 disruptant. As compared to the wild-type strain, the MRG19 disruptant showed a decrease in the ratio of 2-oxoglutarate to glutamate under nitrogen-limited conditions. MRG19 disruptants showed reduced pseudohyphal formation and enhanced sporulation, a phenomenon that occurs under conditions of both nitrogen and carbon withdrawal. These studies revealed that MRG19 regulates carbon and nitrogen metabolism, as well as morphogenetic changes, suggesting that MRG19 is a component of the link between the metabolic status of the cell and the corresponding developmental pathway.

  14. Flooding affects uptake and distribution of carbon and nitrogen in citrus seedlings.

    PubMed

    Martínez-Alcántara, Belén; Jover, Sara; Quiñones, Ana; Forner-Giner, María Ángeles; Rodríguez-Gamir, Juan; Legaz, Francisco; Primo-Millo, Eduardo; Iglesias, Domingo J

    2012-08-15

    Soil flooding has been widely reported to affect large areas of the world. In this work, we investigated the effect of waterlogging on citrus carbon and nitrogen pools and partitioning. Influence on their uptake and translocation was also studied through ¹⁵N and ¹³C labeling to provide insight into the physiological mechanisms underlying the responses. The data indicated that flooding severely reduced photosynthetic activity and affected growth and biomass partitioning. Total nitrogen content and concentration in the plant also progressively decreased throughout the course of the experiment. After 36 days of treatment, nitrogen content of flooded plants had decreased more than 2.3-fold compared to control seedlings, and reductions in nitrogen concentration ranged from 21 to 55% (in roots and leaves, respectively). Specific absorption rate and transport were also affected, leading to important changes in the distribution of this element inside the plant. Additionally, experiments involving labeled nitrogen revealed that ¹⁵N uptake rate and accumulation were drastically decreased at the end of the experiment (93% and 54%, respectively). ¹³CO₂ assimilation into the plant was strongly reduced by flooding, with δ¹³C reductions ranging from 22 to 37% in leaves and roots, respectively. After 36 days, the relative distribution of absorbed ¹³C was also altered. Thus, ¹³C recovery in flooded leaves increased compared to controls, whereas roots exhibited the opposite pattern. Interestingly, when carbohydrate partitioning was examined, the data revealed that sucrose concentration was augmented significantly in roots (37-56%), whereas starch was reduced. In leaves, a marked increase in sucrose was detected from the first sampling onwards (36-66%), and the same patter was observed for starch. Taken together, these results indicate that flooding altered carbon and nitrogen pools and partitioning in citrus. On one hand, reduced nitrogen concentration appears to

  15. The CCAAT box-binding factor stimulates ammonium assimilation in Saccharomyces cerevisiae, defining a new cross-pathway regulation between nitrogen and carbon metabolisms.

    PubMed

    Dang, V D; Bohn, C; Bolotin-Fukuhara, M; Daignan-Fornier, B

    1996-04-01

    In Saccharomyces cerevisiae, carbon and nitrogen metabolisms are connected via the incorporation of ammonia into glutamate; this reaction is catalyzed by the NADP-dependent glutamate dehydrogenase (NADP-GDH) encoded by the GDH1 gene. In this report, we show that the GDH1 gene requires the CCAAT box-binding activator (HAP complex) for optimal expression. This conclusion is based on several lines of evidence: (1) overexpression of GDH1 can correct the growth defect of hap2 and hap3 mutants on ammonium sulfate as a nitrogen source, (ii) Northern (RNA) blot analysis shows that the steady-state level of GDH1 mRNA is strongly lowered in a hap2 mutant, (iii) expression of a GDH1-lacZ fusion is drastically reduced in hap mutants, (iv) NADP-GDH activity is several times lower in the hap mutants compared with that in the isogenic wild-type strain, and finally, (v) site-directed mutagenesis of two consensual HAP binding sites in the GDH1 promoter strongly reduces expression of GDH1 and makes it HAP independent. Expression of GDH1 is also regulated by the carbon source, i.e., expression is higher on lactate than on ethanol, glycerol, or galactose, with the lowest expression being found on glucose. Finally, we show that a hap2 mutation does not affect expression of other genes involved in nitrogen metabolism (GDH2, GLN1, and GLN3 encoding, respectively, the NAD-GDH, glutamine synthetase, and a general activator of several nitrogen catabolic genes). The HAP complex is known to regulate expression of several genes involved in carbon metabolism; its role in the control of GDH1 gene expression, therefore, provides evidence for a cross-pathway regulation between carbon and nitrogen metabolisms.

  16. Diurnal Variations in Photosynthetic Products and Nitrogen Metabolism in Expanding Leaves

    PubMed Central

    Steer, Barrie T.

    1973-01-01

    Expanding leaves of Capsicum frutescens L. cv. California Wonder, Cucumis melo L. cv. Hales Best, and Citrus sinensis L. Osbeck cv. Washington Navel showed a marked diurnal periodicity in the incorporation of 14C from photosynthetically fixed 14CO2 into amino acids. Incorporation was virtually nil at the beginning of the photoperiod, reached a maximum in the 6th to 7th hour and decreased during the latter part of the photoperiod. In Capsicum frutescens this was apparently a reflection of the availability of reduced nitrogen controlled by the activity of nitrate reductase in the leaves. This also controlled the periodicity of the incorporation of 14C into fraction I protein. Possible control mechanisms and the relation of nitrogen metabolism to the periodicity of leaf expansion growth are discussed. PMID:16658402

  17. Application of nitrogen metabolism in autotrophic bacteria to chemosynthetic bioregeneration in space missions, supplement

    NASA Technical Reports Server (NTRS)

    Wixom, R. L.

    1974-01-01

    The chemolithotroph, Hydrogenomonas eutropha, was considered as a life support, bioregenerative system. This project focuses on several metabolic functions that are related to the proposed nitrogen cycle between man and this microbe. Specifically this organism has the capability to utilize as the sole nitrogen source such urine components as urea and fifteen individual amino acids, but not nine other amino acids. The effectiveness of utilization was high for many amino acids. Several specific growth inhibitions were also observed. The enzyme that catalyzes the incorporation of ammonia in the medium into amino acids was identified as a NADP-specific, L-glutamate dehydrogenase. This enzyme has a constitutive nature. This organism can synthesize all of its amino acids from carbon dioxide and ammonia. Therefore with the background literature of multiple pathways of individual amino acid biosyntheses, our evidence to date is consistent with the Hydrogeneomonas group having the same pathway of valine-isoleucine formation as the classical E. coli.

  18. Direct Involvement of the Master Nitrogen Metabolism Regulator GlnR in Antibiotic Biosynthesis in Streptomyces.

    PubMed

    He, Juan-Mei; Zhu, Hong; Zheng, Guo-Song; Liu, Pan-Pan; Wang, Jin; Zhao, Guo-Ping; Zhu, Guo-Qiang; Jiang, Wei-Hong; Lu, Yin-Hua

    2016-12-16

    GlnR, an OmpR-like orphan two-component system response regulator, is a master regulator of nitrogen metabolism in the genus Streptomyces In this work, evidence that GlnR is also directly involved in the regulation of antibiotic biosynthesis is provided. In the model strain Streptomyces coelicolor M145, an in-frame deletion of glnR resulted in markedly increased actinorhodin (ACT) production but reduced undecylprodigiosin (RED) biosynthesis when exposed to R2YE culture medium. Transcriptional analysis coupled with DNA binding studies revealed that GlnR represses ACT but activates RED production directly via the pathway-specific activator genes actII-ORF4 and redZ, respectively. The precise GlnR-binding sites upstream of these two target genes were defined. In addition, the direct involvement of GlnR in antibiotic biosynthesis was further identified in Streptomyces avermitilis, which produces the important anthelmintic agent avermectin. We found that S. avermitilis GlnR (GlnRsav) could stimulate avermectin but repress oligomycin production directly through the respective pathway-specific activator genes, aveR and olmRI/RII To the best of our knowledge, this report describes the first experimental evidence demonstrating that GlnR regulates antibiotic biosynthesis directly through pathway-specific regulators in Streptomyces Our results suggest that GlnR-mediated regulation of antibiotic biosynthesis is likely to be universal in streptomycetes. These findings also indicate that GlnR is not only a master nitrogen regulator but also an important controller of secondary metabolism, which may help to balance nitrogen metabolism and antibiotic biosynthesis in streptomycetes.

  19. [Soil enzyme activities under two forest types as affected by different levels of nitrogen deposition].

    PubMed

    Zhao, Yu-tao; Li, Xue-feng; Han, Shi-jie; Hu, Yan-ling

    2008-12-01

    A simulation test was conducted to study the change trends of soil cellulase, polyphenol oxidase, and sucrase activities under natural broadleaf-Korean pine (Pinus koraiensis) and secondary poplar (Populus davidiana) -birch (Betula platyphylla) mixed forests as affected by 0, 25, and 50 kg x hm(-2) x a(-1) of N deposition. The results showed that the effects of elevated N deposition on test enzyme activities varied with forest type, and short-term nitrogen addition could significantly affect the test enzyme activities. High N deposition decreased soil polyphyneol oxidase activity, and correspondingly, soil cellulase and sucrase activities also had a trend of decrease.

  20. Metabolic Flux Analysis of the Synechocystis sp. PCC 6803 ΔnrtABCD Mutant Reveals a Mechanism for Metabolic Adaptation to Nitrogen-Limited Conditions.

    PubMed

    Nakajima, Tsubasa; Yoshikawa, Katsunori; Toya, Yoshihiro; Matsuda, Fumio; Shimizu, Hiroshi

    2017-03-01

    Metabolic flux redirection during nitrogen-limited growth was investigated in the Synechocystis sp. PCC 6803 glucose-tolerant (GT) strain under photoautotrophic conditions by isotopically non-stationary metabolic flux analysis (INST-MFA). A ΔnrtABCD mutant of Synechocystis sp. PCC 6803 was constructed to reproduce phenotypes arising during nitrogen starvation. The ΔnrtABCD mutant and the wild-type GT strain were cultured under photoautotrophic conditions by a photobioreactor. Intracellular metabolites were labeled over a time course using NaH13CO3 as a carbon source. Based on these data, the metabolic flux distributions in the wild-type and ΔnrtABCD cells were estimated by INST-MFA. The wild-type GT and ΔnrtABCD strains displayed similar distribution patterns, although the absolute levels of metabolic flux were lower in ΔnrtABCD. Furthermore, the relative flux levels for glycogen metabolism, anaplerotic reactions and the oxidative pentose phosphate pathway were increased in ΔnrtABCD. This was probably due to the increased expression of enzyme genes that respond to nitrogen depletion. Additionally, we found that the ratio of ATP/NADPH demand increased slightly in the ΔnrtABCD mutant. These results indicated that futile ATP consumption increases under nitrogen-limited conditions because the Calvin-Benson cycle and the oxidative pentose phosphate pathway form a metabolic futile cycle that consumes ATP without CO2 fixation and NADPH regeneration.

  1. Ionizing Radiation Impairs T Cell Activation by Affecting Metabolic Reprogramming.

    PubMed

    Li, Heng-Hong; Wang, Yi-Wen; Chen, Renxiang; Zhou, Bin; Ashwell, Jonathan D; Fornace, Albert J

    2015-01-01

    Ionizing radiation has a variety of acute and long-lasting adverse effects on the immune system. Whereas measureable effects of radiation on immune cell cytotoxicity and population change have been well studied in human and animal models, little is known about the functional alterations of the surviving immune cells after ionizing radiation. The objective of this study was to delineate the effects of radiation on T cell function by studying the alterations of T cell receptor activation and metabolic changes in activated T cells isolated from previously irradiated animals. Using a global metabolomics profiling approach, for the first time we demonstrate that ionizing radiation impairs metabolic reprogramming of T cell activation, which leads to substantial decreases in the efficiency of key metabolic processes required for activation, such as glucose uptake, glycolysis, and energy metabolism. In-depth understanding of how radiation impacts T cell function highlighting modulation of metabolism during activation is not only a novel approach to investigate the pivotal processes in the shift of T cell homeostasis after radiation, it also may lead to new targets for therapeutic manipulation in the combination of radiotherapy and immune therapy. Given that appreciable effects were observed with as low as 10 cGy, our results also have implications for low dose environmental exposures.

  2. Arsenic induces structural and compositional colonic microbiome change and promotes host nitrogen and amino acid metabolism.

    PubMed

    Dheer, Rishu; Patterson, Jena; Dudash, Mark; Stachler, Elyse N; Bibby, Kyle J; Stolz, Donna B; Shiva, Sruti; Wang, Zeneng; Hazen, Stanley L; Barchowsky, Aaron; Stolz, John F

    2015-12-15

    Chronic exposure to arsenic in drinking water causes cancer and non-cancer diseases. However, mechanisms for chronic arsenic-induced pathogenesis, especially in response to lower exposure levels, are unclear. In addition, the importance of health impacts from xeniobiotic-promoted microbiome changes is just being realized and effects of arsenic on the microbiome with relation to disease promotion are unknown. To investigate impact of arsenic exposure on both microbiome and host metabolism, the stucture and composition of colonic microbiota, their metabolic phenotype, and host tissue and plasma metabolite levels were compared in mice exposed for 2, 5, or 10weeks to 0, 10 (low) or 250 (high) ppb arsenite (As(III)). Genotyping of colonic bacteria revealed time and arsenic concentration dependent shifts in community composition, particularly the Bacteroidetes and Firmicutes, relative to those seen in the time-matched controls. Arsenic-induced erosion of bacterial biofilms adjacent to the mucosal lining and changes in the diversity and abundance of morphologically distinct species indicated changes in microbial community structure. Bacterical spores increased in abundance and intracellular inclusions decreased with high dose arsenic. Interestingly, expression of arsenate reductase (arsA) and the As(III) exporter arsB, remained unchanged, while the dissimilatory nitrite reductase (nrfA) gene expression increased. In keeping with the change in nitrogen metabolism, colonic and liver nitrite and nitrate levels and ratios changed with time. In addition, there was a concomitant increase in pathogenic arginine metabolites in the mouse circulation. These data suggest that arsenic exposure impacts the microbiome and microbiome/host nitrogen metabolism to support disease enhancing pathogenic phenotypes.

  3. Quantitative Relationships between Photosynthetic, Nitrogen Fixing, and Fermentative H2 Metabolism in a Photosynthetic Microbial Mat

    NASA Technical Reports Server (NTRS)

    Hoehler, Tori M.; Albert, Daniel B.; Bebout, Brad M.; Turk, Kendra A.; DesMarais, David J.

    2004-01-01

    The ultimate potential of any microbial ecosystem to contribute chemically to its environment - and therefore, to impact planetary biogeochemistry or to generate recognizable biosignatures - depends not only on the individual metabolic capabilities of constituent organisms, but also on how those capabilities are expressed through interactions with neighboring organisms. This is particularly important for microbial mats, which compress an extremely broad range of metabolic potential into a small and dynamic system. H2 participates in many of these metabolic processes, including the major elemental cycling processes of photosynthesis, nitrogen fixation, sulfate reduction, and fermentation, and may therefore serve as a mediator of microbial interactions within the mat system. Collectively, the requirements of energy, electron transfer, and biomass element stoichiometry suggest quantitative relationships among the major element cycling processes, as regards H2 metabolism We determined experimentally the major contributions to 32 cycling in hypersaline microbial mats from Baja California, Mexico, and compared them to predicted relationships. Fermentation under dark, anoxic conditions is quantitatively the most important mechanism of H2 production, consistent with expectations for non-heterocystous mats such as those under study. Up to 16% of reducing equivalents fixed by photosynthesis during the day may be released by this mechanism. The direct contribution of nitrogen fixation to H2 production is small in comparison, but this process may indirectly stimulate substantial H2 generation, by requiring higher rates of fermentation. Sulfate reduction, aerobic consumption, diffusive and ebulitive loss, and possibly H2-based photoreduction of CO2 serve as the principal H2 sinks. Collectively, these processes interact to create an orders-of-magnitude daily variation in H2 concentrations and fluxes, and thereby in the oxidation-reduction potential that is imposed on microbial

  4. Arsenic induces structural and compositional colonic microbiome change and promotes host nitrogen and amino acid metabolism

    PubMed Central

    Dheer, Rishu; Patterson, Jena; Dudash, Mark; Stachler, Elyse N.; Bibby, Kyle J.; Stolz, Donna B.; Shiva, Sruti; Wang, Zeneng; Hazen, Stanley L.; Barchowsky, Aaron; Stolz, John F.

    2015-01-01

    Chronic exposure to arsenic in drinking water causes cancer and non-cancer diseases. However, mechanisms for chronic arsenic-induced pathogeneis, especially in response to lower exposure levels, are unclear. In addition, the importance of health impacts from xeniobiotic-promoted microbiome changes is just being realized and effects of arsenic on the microbiome with relation to disease promotion are unknown. To investigate impact of arsenic exposure on both microbiome and host metabolism, the stucture and composition of colonic microbiota, their metabolic phenotype, and host tissue and plasma metabolite levels were compared in mice exposed for 2, 5, or 10 weeks to 0, 10 (low) or 250 (high) ppb arsenite (As(III)). Genotyping of colonic bacteria revealed time and arsenic concentration dependent shifts in community composition, particularly the Bacteroidetes and Firmicutes, relative to those seen in the time-matched controls. Arsenic-induced erosion of bacterial biofilms adjacent to the mucosal lining and changes in the diversity and abundance of morphologically distinct species indicated changes in microbial community structure. Bacterical spores increased in abundance and intracellular inclusions decreased with high dose arsenic. Interestingly, expression of arsenate reductase (arsA) and the As(III) exporter arsB, remained unchanged, while the dissimilatory nitrite reductase (nrfA) gene expression increased. In keeping with the change in nitrogen metabolism, colonic and liver nitrite and nitrate levels and ratios changed with time. In addition, there was a concomitant increase in pathogenic arginine metabolites in the mouse circulation. These data suggest that arsenic exposure impacts the microbiome and microbiome/host nitrogen metabolism to support disease enhancing pathogenic phenotypes. PMID:26529668

  5. METABOLIC ENGINEERING TO DEVELOP A PATHWAY FOR THE SELECTIVE CLEAVAGE OF CARBON-NITROGEN BONDS

    SciTech Connect

    John J. Kilbane II

    2004-10-01

    The objective of the project is to develop biochemical pathways for the selective cleavage of C-N bonds in molecules found in petroleum. The initial phase of the project was focused on the isolation or development of an enzyme capable of cleaving the C-N bond in aromatic amides, specifically 2-aminobiphenyl. The objective of the second phase of the research will be to construct a biochemical pathway for the selective removal of nitrogen from carbazole by combining the carA genes from Sphingomonas sp. GTIN11 with the gene(s) encoding an appropriate deaminase. The objective of the final phase of the project will be to develop derivative C-N bond cleaving enzymes that have broader substrate ranges and to demonstrate the use of such strains to selectively remove nitrogen from petroleum. During the first year of the project (October, 2002-September, 2003) enrichment culture experiments resulted in the isolation of microbial cultures that utilize aromatic amides as sole nitrogen sources, several amidase genes were cloned and were included in directed evolution experiments to obtain derivatives that can cleave C-N bonds in aromatic amides, and the carA genes from Sphingomonas sp. GTIN11, and Pseudomonas resinovorans CA10 were cloned in vectors capable of replicating in Escherichia coli. During the second year of the project (October, 2003-September, 2004) enrichment culture experiments succeeded in isolating a mixed bacterial culture that can utilize 2-aminobiphenyl as a sole nitrogen source, directed evolution experiments were focused on the aniline dioxygenase enzyme that is capable of deaminating aniline, and expression vectors were constructed to enable the expression of genes encoding C-N bond cleaving enzymes in Rhodococcus hosts. The construction of a new metabolic pathway to selectively remove nitrogen from carbazole and other molecules typically found in petroleum should lead to the development of a process to improve oil refinery efficiency by reducing the

  6. Natural toxins that affect plant amino acid metabolism

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A diverse range of natural compounds interfere with the synthesis and other aspects of amino acid metabolism. Some are amino acid analogues, but most are not. This review covers a number of specific natural phytotoxic compounds by molecular target site. Inhibition of glutamine synthetase is of part...

  7. Does nitrogen gas bubbled through a low density polymer gel dosimeter solution affect the polymerization process?

    PubMed Central

    Shahbazi-Gahrouei, Daryoush; Gholami, Mehrdad; Pourfallah, Tayyeb Allahverdi; Keshtkar, Mohammad

    2015-01-01

    Background: On account of the lower electron density in the lung tissue, the dose distribution in the lung cannot be verified with the existing polymer gel dosimeters. Thus, the aims of this study are to make a low density polymer gel dosimeter and investigate the effect of nitrogen gas bubbles on the R2 responses and its homogeneity. Materials and Methods: Two different types of low density polymer gel dosimeters were prepared according to a composition proposed by De Deene, with some modifications. In the first type, no nitrogen gas was perfused through the gel solution and water. In the second type, to expel the dissolved oxygen, nitrogen gas was perfused through the water and gel solution. The post-irradiation times in the gels were 24 and 5 hours, respectively, with and without perfusion of nitrogen gas through the water and gel solution. Results: In the first type of gel, there was a linear correlation between the doses and R2 responses from 0 to 12 Gy. The fabricated gel had a higher dynamic range than the other low density polymer gel dosimeter; but its background R2 response was higher. In the second type, no difference in R2 response was seen in the dose ranges from 0 to 18 Gy. Both gels had a mass density between 0.35 and 0.45 g.cm-3 and CT values of about -650 to -750 Hounsfield units. Conclusion: It appeared that reactions between gelatin-free radicals and monomers, due to an increase in the gel temperature during rotation in the household mixer, led to a higher R2-background response. In the second type of gel, it seemed that the collapse of the nitrogen bubbles was the main factor that affected the R2-responses. PMID:26015914

  8. Factors affecting energy and nitrogen efficiency of dairy cows: a meta-analysis.

    PubMed

    Phuong, H N; Friggens, N C; de Boer, I J M; Schmidely, P

    2013-01-01

    A meta-analysis was performed to explore the correlation between energy and nitrogen efficiency of dairy cows, and to study nutritional and animal factors that influence these efficiencies, as well as their relationship. Treatment mean values were extracted from 68 peer-reviewed studies, including 306 feeding trials. The main criterion for inclusion of a study in the meta-analysis was that it reported, or permitted calculation of, energy efficiency (Eeff; energy in milk/digestible energy intake) and nitrogen efficiency (Neff; nitrogen in milk/digestible nitrogen intake) at the digestible level (digestible energy or digestible protein). The effect of nutritional and animal variables, including neutral detergent fiber, acid detergent fiber (ADF), digestible energy, digestible protein, proportion of concentrate (PCO), dry matter intake, milk yield, days in milk, and body weight, on Eeff, Neff, and the Neff:Eeff ratio was analyzed using mixed models. The interstudy correlation between Eeff and Neff was 0.62, whereas the intrastudy correlation was 0.30. The higher interstudy correlation was partly due to milk yield and dry matter intake being present in both Eeff and Neff. We, therefore, also explored the Neff:Eeff ratio. Energy efficiency was negatively associated with ADF and PCO, whereas Neff was negatively associated with ADF and digestible energy. The Neff:Eeff ratio was affected by ADF and PCO only. In conclusion, the results indicate a possibility to maximize feed efficiency in terms of both energy and nitrogen at the same time. In other words, an improvement in Eeff would also mean an improvement in Neff. The current study also shows that these types of transverse data are not sufficient to study the effect of animal factors, such as days in milk, on feed efficiency. Longitudinal measurements per animal would probably be more appropriate.

  9. Mineral and nitrogen balance study - Results of metabolic observations on Skylab II 28-day orbital mission

    NASA Technical Reports Server (NTRS)

    Whedon, G. D.; Lutwak, L.; Reid, J.; Rambaut, P.; Whittle, M.; Smith, M.; Leach, C.

    1975-01-01

    The prediction that various stresses of flight, particularly weightlessness, would bring about significant derangements in the metabolism of the musculoskeletal system has been based on various balance-study observations of long-term immobilized or inactive bed rest. The three astronauts of Skylab II consumed a planned dietary intake of major metabolic elements in mixed foods and beverages and provided virtually complete collections of excreta for 31 days preflight, 28 days inflight, and 17 days postflight. Analyses showed that, in varying degree among the crewmen, urinary calcium increased gradually during flight in a pattern similar to that observed in bed-rest studies. Fecal calcium excretion did not change significantly, but calcium balance, owing to the urinary calcium rise, became either negative or less positive than in preflight measurement. Increased excretion and negative nitrogen and phosphorus balances inflight indicated appreciable loss of muscle tissue in all three crewmen. Significant losses also occurred inflight in potassium, sodium, and magnesium. Based on the similarity in pattern and degree between these observations of calcium, phosphorus, and nitrogen loss, musculoskeletal integrity would not be threatened in space flights of up to at least 3 months. However, if similar changes occur in the planed Skylab flights for considerably more than 28 days, concern for capable musculoskeletal function should be serious for flights of very many months' duration.

  10. Nitrogen metabolism and kidney function in the Nubian ibex (Capra ibex nubiana).

    PubMed

    Choshniak, I; Arnon, H

    1985-01-01

    The nitrogen economy of the Nubian ibex (Capra ibex nubiana), a ruminant that inhabits harsh deserts, was studied in the laboratory when fed three diets of different quality. Even on the low quality roughage (wheat straw) the ibex was found capable of balancing its nitrogen economy. On feeds low in protein, recycling of urea played a major role in helping the ibex maintaining a balanced nitrogen metabolism. When on wheat straw, the ibex recycled 71.6% of the urea synthesized in its liver. When on feeds lower in protein, blood urea concentration dropped (from 11.4 mM when on alfalfa hay to 3.2 mM when on wheat straw). GFR that amounted to 44.28 ml/min when on alfalfa hay decreased to 28.97 ml/min when on wheat straw. Reabsorption of urea amounted to 48% of the urea filtered when on alfalfa hay and increased to 78.8% on wheat straw.

  11. Comparison of Nitrogen Oxide Metabolism among Diverse Ammonia-Oxidizing Bacteria

    PubMed Central

    Kozlowski, Jessica A.; Kits, K. Dimitri; Stein, Lisa Y.

    2016-01-01

    Ammonia-oxidizing bacteria (AOB) have well characterized genes that encode and express nitrite reductases (NIR) and nitric oxide reductases (NOR). However, the connection between presence or absence of these and other genes for nitrogen transformations with the physiological production of nitric oxide (NO) and nitrous oxide (N2O) has not been tested across AOB isolated from various trophic states, with diverse phylogeny, and with closed genomes. It is therefore unclear if genomic content for nitrogen oxide metabolism is predictive of net N2O production. Instantaneous microrespirometry experiments were utilized to measure NO and N2O emitted by AOB during active oxidation of ammonia (NH3) or hydroxylamine (NH2OH) and through a period of anoxia. This data was used in concert with genomic content and phylogeny to assess whether taxonomic factors were predictive of nitrogen oxide metabolism. Results showed that two oligotrophic AOB strains lacking annotated NOR-encoding genes released large quantities of NO and produced N2O abiologically at the onset of anoxia following NH3-oxidation. Furthermore, high concentrations of N2O were measured during active O2-dependent NH2OH oxidation by the two oligotrophic AOB in contrast to non-oligotrophic strains that only produced N2O at the onset of anoxia. Therefore, complete nitrifier denitrification did not occur in the two oligotrophic strains, but did occur in meso- and eutrophic strains, even in Nitrosomonas communis Nm2 that lacks an annotated NIR-encoding gene. Regardless of mechanism, all AOB strains produced measureable N2O under tested conditions. This work further confirms that AOB require NOR activity to enzymatically reduce NO to N2O in the nitrifier denitrification pathway, and also that abiotic reactions play an important role in N2O formation, in oligotrophic AOB lacking NOR activity. PMID:27462312

  12. Growth versus metabolic tissue replacement in mouse tissues determined by stable carbon and nitrogen isotope analysis

    NASA Astrophysics Data System (ADS)

    Macavoy, S. E.; Jamil, T.; Macko, S. A.; Arneson, L. S.

    2003-12-01

    Stable isotope analysis is becoming an extensively used tool in animal ecology. The isotopes most commonly used for analysis in terrestrial systems are those of carbon and nitrogen, due to differential carbon fractionation in C3 and C4 plants, and the approximately 3‰ enrichment in 15N per trophic level. Although isotope signatures in animal tissues presumably reflect the local food web, analysis is often complicated by differential nutrient routing and fractionation by tissues, and by the possibility that large organisms are not in isotopic equilibrium with the foods available in their immediate environment. Additionally, the rate at which organisms incorporate the isotope signature of a food through both growth and metabolic tissue replacement is largely unknown. In this study we have assessed the rate of carbon and nitrogen isotopic turnover in liver, muscle and blood in mice following a diet change. By determining growth rates, we were able to determine the proportion of tissue turnover caused by growth versus that caused by metabolic tissue replacement. Growth was found to account for approximately 10% of observed tissue turnover in sexually mature mice (Mus musculus). Blood carbon was found to have the shortest half-life (16.9 days), followed by muscle (24.7 days). Liver carbon turnover was not as well described by the exponential decay equations as other tissues. However, substantial liver carbon turnover was observed by the 28th day after diet switch. Surprisingly, these tissues primarily reflect the carbon signature of the protein, rather than carbohydrate, source in their diet. The nitrogen signature in all tissues was enriched by 3 - 5‰ over their dietary protein source, depending on tissue type, and the isotopic turnover rates were comparable to those observed in carbon.

  13. Fusion and metabolism of plant cells as affected by microgravity.

    PubMed

    Hampp, R; Hoffmann, E; Schönherr, K; Johann, P; De Filippis, L

    1997-01-01

    Plant cell protoplasts derived from leaf tissue of two different tobacco species (Nicotiana tabacum., N. rustica L.) were exposed to short-term (sounding rocket experiments) and long-term (spacelab) microgravity environments in order to study both (electro) cell fusion and cell metabolism during early and later stages of tissue regeneration. The period of exposure to microgravity varied from 10 min (sounding rocket) to 10 d (space shuttle). The process of electro fusion of protoplasts was improved under conditions of microgravity: the time needed to establish close membrane contact between protoplasts (alignment time) was reduced (5 as compared to 15 s under 1 g) and numbers of fusion products between protoplasts of different specific density were increased by a factor of about 10. In addition, viability of fusion products, as shown by the ability to form callus, increased from about 60% to more than 90%. Regenerated fusion products obtained from both sounding-rocket and spacelab experiments showed a wide range of intermediate properties between the two parental plants. This was verified by isozyme analysis and random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). In order to address potential metabolic responses, more general markers such as the overall energy state (ATP/ADP ratio), the redox charge of the diphosphopyridine nucleotide system (NADH/NAD ratio), and the pool size of fructose-2,6-bisphosphate (Fru 2,6 bisp), a regulator of the balance between glycolysis and gluconeogenesis, were determined. Responses of these parameters were different with regard to short-term and long-term exposure. Shortly after transition to reduced gravitation (sounding rocket) ratios of ATP/ADP exhibited strong fluctuation while the pool size of NAD decreased (indicating an increased NADH/NAD ratio) and that of Fru 2,6 bisp increased. As similar changes can be observed under stress conditions, this response is probably indicative of a metabolic stress

  14. Infectious, inflammatory, and metabolic diseases affecting the athlete's spine.

    PubMed

    Metz, Lionel N; Wustrack, Rosanna; Lovell, Alberto F; Sawyer, Aenor J

    2012-07-01

    Sports and weight-bearing activities can have a positive effect on bone health in the growing, mature, or aging athlete. However, certain athletic activities and training regimens may place the athlete at increased risk for stress fractures in the spine. In addition, some athletes have an underlying susceptibility to fracture due to either systemic or focal abnormalities. It is important to identify and treat these athletes in order to prevent stress fractures and reduce the risk of osteoporosis in late adulthood. Therefore, the pre-participation physical examination offers a unique opportunity to screen athletes for metabolic bone disease through the history and physical examination. Positive findings warrant a thorough workup including a metabolic bone laboratory panel, and possibly a DEXA scan, which includes a lateral spine view.

  15. Protein-based biorefining: metabolic engineering for production of chemicals and fuel with regeneration of nitrogen fertilizers.

    PubMed

    Wernick, David G; Liao, James C

    2013-02-01

    Threats to stable oil supplies and concerns over environmental emissions have pushed for renewable biofuel developments to minimize dependence on fossil resources. Recent biofuel progress has moved towards fossil resource-independent carbon cycles, but environmental issues regarding use of nitrogen fertilizers have not been addressed on a global scale. The recently demonstrated conversion of waste protein biomass into advanced biofuels and renewable chemicals, while recycling nitrogen fertilizers, offers a glimpse of the efforts needed to balance the nitrogen cycle at scale. In general, the catabolism of protein into biofuels is challenging because of physiological regulation and thermodynamic limitations. This conversion became possible with metabolic engineering around ammonia assimilation, intracellular nitrogen flux, and quorum sensing. This review highlights the metabolic engineering solutions in transforming those cellular processes into driving forces for the high yield of chemical products from protein.

  16. Corn silage management III: effects of hybrid, maturity, and processing on nitrogen metabolism and ruminal fermentation.

    PubMed

    Johnson, L M; Harrison, J H; Davidson, D; Swift, M; Mahanna, W C; Shinners, K

    2002-11-01

    Two experiments were conducted to evaluate the effects of maturity and mechanical processing of two hybrids of whole plant corn silage on DM and OM digestibility, nitrogen metabolism, ruminal fermentation, and milk production and composition in lactating Holstein cows. In the first experiment, Pioneer hybrid 3845 whole plant corn was harvested at hard dough, one-third milkline, and two-thirds milkline with a theoretical length-of-cut of 6.4 mm. At each stage of maturity, corn was harvested with (1-mm roll clearance) and without (15.9-mm roll clearance) mechanical processing using a John Deere 5830 harvester with an on-board kernel processor. In the second experiment, Pioneer hybrids 3845 and Quanta were harvested at one-third milkline, two-thirds milkline, and blackline stages of maturity with and without mechanical processing. The theoretical length-of-cut was 12.7 mm. Total tract DM and OM digestibilities were lower for cows fed diets containing processed corn silage in experiment 1, and tended to be lower for cows fed diets containing unprocessed corn silage in experiment 2. Ruminal acetate concentrations were greater and ruminal propionate concentrations were lower 2 and 6 h after feeding for cows fed diets containing corn silage harvested at physiological maturity in experiment 2. This was due to decreased digestion of starch at advanced maturities in experiment 2. Ruminal pH tended to decline rapidly after feeding for cows fed hybrid Quanta (2 h) compared to hybrid 3845 (5 h) corn silage based diets. Ruminal acetate concentrations decreased and ruminal propionate concentrations increased 2 and 6 h after feeding for cows fed diets containing hybrid Quanta corn silage compared to hybrid 3845 corn silage. This was related to a greater starch concentration in the corn silage, greater starch intake, and increased rate of starch digestion for cows fed hybrid Quanta corn silage-based diets. Microbial nitrogen flow was lower and feed nitrogen flow was greater for

  17. Metatranscriptomics reveal differences in in situ energy and nitrogen metabolism among hydrothermal vent snail symbionts

    PubMed Central

    Sanders, J G; Beinart, R A; Stewart, F J; Delong, E F; Girguis, P R

    2013-01-01

    Despite the ubiquity of chemoautotrophic symbioses at hydrothermal vents, our understanding of the influence of environmental chemistry on symbiont metabolism is limited. Transcriptomic analyses are useful for linking physiological poise to environmental conditions, but recovering samples from the deep sea is challenging, as the long recovery times can change expression profiles before preservation. Here, we present a novel, in situ RNA sampling and preservation device, which we used to compare the symbiont metatranscriptomes associated with Alviniconcha, a genus of vent snail, in which specific host–symbiont combinations are predictably distributed across a regional geochemical gradient. Metatranscriptomes of these symbionts reveal key differences in energy and nitrogen metabolism relating to both environmental chemistry (that is, the relative expression of genes) and symbiont phylogeny (that is, the specific pathways employed). Unexpectedly, dramatic differences in expression of transposases and flagellar genes suggest that different symbiont types may also have distinct life histories. These data further our understanding of these symbionts' metabolic capabilities and their expression in situ, and suggest an important role for symbionts in mediating their hosts' interaction with regional-scale differences in geochemistry. PMID:23619306

  18. Differences in nitrogen metabolism between Cryptococcus neoformans and C. gattii, the two etiologic agents of cryptococcosis.

    PubMed

    Ngamskulrungroj, Popchai; Chang, Yun; Roh, Jamin; Kwon-Chung, Kyung J

    2012-01-01

    Two members of the Cryptococcus neoformans-gattii species complex, the etiologic agents of cryptococcosis, can be differentiated by biological, biochemical, serological and molecular typing techniques. Based on their differences in carbon and nitrogen utilization patterns, cost effective and very specific diagnostic tests using D-proline and canvanine-glycine-bromthymol blue (CGB) media have been formulated and are widely used for identification of the two species. However, these methods have yet to be tested for strains with confirmed molecular types to assess the degree of specificity for each molecular type in the two species. We collected global isolates of every major molecular type available and tested their patterns of nitrogen utilization. We confirmed specificity of the CGB test to be 100% regardless of molecular type while the D-proline test yielded 8-38% false negative results in three of the four C. gattii molecular types, VGI-VGIII. The utilization pattern of a new set of amino acids: D-alanine, L-tryptophan and L-phenylalanine, showed species specificity comparable to that of D-proline. We discovered that the transcription factor Gat1 (Are1) regulates the utilization of nitrogen differently between C. neoformans and C. gattii strains. Unlike in C. neoformans, expression of the genes encoding glycine decarboxylase complex in C. gatti was only partially suppressed by nitrogen catabolite repression in the presence of ammonium. GAT1 in C. neoformans controlled the induction of three of the four genes encoding the glycine decarboxylase complex when glycine was used as the sole nitrogen source while in C. gattii its regulation of these genes was less stringent. Moreover, while virulence of C. neoformans strains in mice was not affected by Gat1, the transcription factor positively influenced the virulence of C. gattii strain.

  19. How aneuploidy affects metabolic control and causes cancer.

    PubMed Central

    Rasnick, D; Duesberg, P H

    1999-01-01

    The complexity and diversity of cancer-specific phenotypes, including de-differentiation, invasiveness, metastasis, abnormal morphology and metabolism, genetic instability and progression to malignancy, have so far eluded explanation by a simple, coherent hypothesis. However, an adaptation of Metabolic Control Analysis supports the 100-year-old hypothesis that aneuploidy, an abnormal number of chromosomes, is the cause of cancer. The results demonstrate the currently counter-intuitive principle that it is the fraction of the genome undergoing differential expression, not the magnitude of the differential expression, that controls phenotypic transformation. Transforming the robust normal phenotype into cancer requires a twofold increase in the expression of thousands of normal gene products. The massive change in gene dose produces highly non-linear (i.e. qualitative) changes in the physiology and metabolism of cells and tissues. Since aneuploidy disrupts the natural balance of mitosis proteins, it also explains the notorious genetic instability of cancer cells as a consequence of the perpetual regrouping of chromosomes. In view of this and the existence of non-cancerous aneuploidy, we propose that cancer is the phenotype of cells above a certain threshold of aneuploidy. This threshold is reached either by the gradual, stepwise increase in the level of aneuploidy as a consequence of the autocatalysed genetic instability of aneuploid cells or by tetraploidization followed by a gradual loss of chromosomes. Thus the initiation step of carcinogenesis produces aneuploidy below the threshold for cancer, and the promotion step increases the level of aneuploidy above this threshold. We conclude that aneuploidy offers a simple and coherent explanation for all the cancer-specific phenotypes. Accordingly, the gross biochemical abnormalities, abnormal cellular size and morphology, the appearance of tumour-associated antigens, the high levels of secreted proteins responsible for

  20. Elucidating Sources and Factors Affecting Delivery of Nitrogen to Surface Waters of New York State

    NASA Astrophysics Data System (ADS)

    Golden, H. E.; Boyer, E. W.; Burns, D. A.; Elliott, E.; Kendall, C.; Butler, T.

    2005-12-01

    Rapid changes in power generation, transportation, and agriculture have appreciably altered nitrogen (N) cycling at regional scales, increasing N inputs to landscapes and surface waters. Numerous studies have linked this surplus N to a host of concerns, including eutrophication and violations in drinking water standards. Inputs of N nation-wide have increased during recent decades, primarily from the production and use of fertilizers, the planting of N-fixing crops, and the combustion of fossil fuels. The role of atmospheric N sources is of particular concern in New York, as rates of atmospheric N deposition in the northeast are among the highest in the nation. Our work aims to quantify nitrogen sources and fate in watersheds throughout the state. Further, we intend to elucidate factors controlling the retention and release of N to surface waters. We quantify nitrogen inputs through both measurement data (e.g., from wet and dry atmospheric deposition, precipitation, streamflow, water quality, and isotopic tracers) and from synoptic spatial databases (e.g., of terrain, land use, and fertilizer inputs). We present preliminary results from large catchments in contrasting spatial settings across the state (different land use configurations and atmospheric deposition gradients), illustrating the contribution of nitrogen sources to each region and factors affecting delivery to surface waters. Further, we present 30 years of temporal data from a large watershed (Fall Creek) in the Finger Lakes region of the state to demonstrate how hydrological and biogeochemical factors, over seasons and under varying hydrological regimes, combine to control N dynamics in surface waters. Our collective work provides information that is necessary to develop sound strategies for understanding and managing nutrients at regional scales.

  1. Seasonal Temperature Changes Do Not Affect Cardiac Glucose Metabolism

    PubMed Central

    Schildt, Jukka; Loimaala, Antti; Hippeläinen, Eero; Nikkinen, Päivi; Ahonen, Aapo

    2015-01-01

    FDG-PET/CT is widely used to diagnose cardiac inflammation such as cardiac sarcoidosis. Physiological myocardial FDG uptake often creates a problem when assessing the possible pathological glucose metabolism of the heart. Several factors, such as fasting, blood glucose, and hormone levels, influence normal myocardial glucose metabolism. The effect of outdoor temperature on myocardial FDG uptake has not been reported before. We retrospectively reviewed 29 cancer patients who underwent PET scans in warm summer months and again in cold winter months. We obtained myocardial, liver, and mediastinal standardized uptake values (SUVs) as well as quantitative cardiac heterogeneity and the myocardial FDG uptake pattern. We also compared age and body mass index to other variables. The mean myocardial FDG uptake showed no significant difference between summer and winter months. Average outdoor temperature did not correlate significantly with myocardial SUVmax in either summer or winter. The heterogeneity of myocardial FDG uptake did not differ significantly between seasons. Outdoor temperature seems to have no significant effect on myocardial FDG uptake or heterogeneity. Therefore, warming the patients prior to attending cardiac PET studies in order to reduce physiological myocardial FDG uptake seems to be unnecessary. PMID:26858844

  2. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2006-01-01

    In 2005, ammonia was produced by 15 companies at 26 plants in 16 states in the United States. Of the total ammonia production capacity, 55% was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas. US producers operated at 66% of their rated capacity. In descending order, Koch Nitrogen, Terra Industries, CF Industries, Agrium and PCS Nitrogen accounted for 81% of the US ammonia production capacity.

  3. Loading-induced changes in synovial fluid affect cartilage metabolism.

    PubMed

    van de Lest, C H; van den Hoogen, B M; van Weeren, P R

    2000-01-01

    The object of this study was to determine whether changes in the synovial fluid (SF) induced by in vivo loading can alter the metabolic activity of chondrocytes in vitro, and, if so, whether insulin-like growth factor-I (IGF-I) is responsible for this effect. Therefore, SF was collected from ponies after a period of box rest and after they had been exercised for a week. Normal, unloaded articular cartilage explants were cultured in 20% solutions of these SFs for 4 days and chondrocyte bioactivity was determined by glycosaminoglycan (GAG) turnover (i.e., the incorporation of 35SO4 into GAG and the release of GAG into the medium). Furthermore, the extent to which the bioactivity is IGF-I-dependent was determined in a cartilage explant culture in 20% SF, in the presence and absence of anti-IGF-I antibodies. In explants cultured in post-exercise SF, GAG synthesis was enhanced and GAG release was diminished when compared to cultures in pre-exercise SF. SF analysis showed that IGF-I and IGFBP-3 levels were increased in post-exercise SF. There was a positive correlation between IGF-I levels and proteoglycan synthesis, but no correlation between IGF-I levels and proteoglycan release. Addition of anti-IGF-I antibodies significantly inhibited stimulation of proteoglycan synthesis in explants cultured in SF with 40%. However, there was no difference in inhibition of proteoglycan synthesis between pre- and post-exercise SF which indicated that the relative contribution of IGF-I in the stimulating effect of SF did not change. Proteoglycan release was not influenced by the presence of anti-IGF-I antibodies. It is concluded that chondrocyte metabolic activity is at least partially regulated by changes in the SF induced by in vivo loading. Exercise altered the SF in a way that it had a favourable effect on cartilage PG content by enhancing the PG synthesis and reducing the PG breakdown. IGF-I is an important contributor to the overall stimulating effect of SF on cartilage

  4. Improvement of nitrogen accumulation and metabolism in rice (Oryza sativa L.) by the endophyte Phomopsis liquidambari.

    PubMed

    Yang, Bo; Ma, Hai-Yan; Wang, Xiao-Mi; Jia, Yong; Hu, Jing; Li, Xia; Dai, Chuan-Chao

    2014-09-01

    The fungal endophyte Phomopsis liquidambari can enhance nitrogen (N) uptake and metabolism of rice plants under hydroponic conditions. To investigate the effects of P. liquidambari on N accumulation and metabolism in rice (Oryza sativa L.) under field conditions during the entire growing season (S1, the seedling stage; S2, the tillering stage; S3, the heading stage; S4, the ripening stage), we utilized pot experiments to examine metabolic and physiological levels in both shoot and root tissues of rice, with endophyte (E+) and without endophyte (E-), in response to three different N levels. We found that under low-N treatment, P. liquidambari symbiosis increased the rice yield and N use efficiency by 12% and by 11.59%, respectively; that the total N contents in E+ rice plants at the four growth stages were separately increased by 29.05%, 14.65%, 21.06% and 18.38%, respectively; and that the activities of nitrate reductase and glutamine synthetase in E+ rice roots and shoots were significantly increased by fungal infection during the S1 to S3 stages. Moreover, P. liquidambari significantly increased the free NH4(+), NO3(-), amino acid and soluble protein contents in infected rice tissues under low-N treatment during the S1 to S3 stages. The obtained results offer novel data concerning the systemic changes induced by P. liquidambari in rice during the entire growth period and confirm the hypothesis that the rice-P. liquidambari interaction improved the N accumulation and metabolism of rice plants, consequently increasing rice N utilization in nutrient-limited soil.

  5. Can Cholesterol Metabolism Modulation Affect Brain Function and Behavior?

    PubMed

    Cartocci, Veronica; Servadio, Michela; Trezza, Viviana; Pallottini, Valentina

    2017-02-01

    Cholesterol is an important component for cell physiology. It regulates the fluidity of cell membranes and determines the physical and biochemical properties of proteins. In the central nervous system, cholesterol controls synapse formation and function and supports the saltatory conduction of action potential. In recent years, the role of cholesterol in the brain has caught the attention of several research groups since a breakdown of cholesterol metabolism has been associated with different neurodevelopmental and neurodegenerative diseases, and interestingly also with psychiatric conditions. The aim of this review is to summarize the current knowledge about the connection between cholesterol dysregulation and various neurologic and psychiatric disorders based on clinical and preclinical studies. J. Cell. Physiol. 232: 281-286, 2017. © 2016 Wiley Periodicals, Inc.

  6. How does fish metamorphosis affect aromatic amino acid metabolism?

    PubMed

    Pinto, Wilson; Figueira, Luís; Dinis, Maria Teresa; Aragão, Cláudia

    2009-02-01

    Aromatic amino acids (AAs, phenylalanine and tyrosine) may be specifically required during fish metamorphosis, since they are the precursors of thyroid hormones which regulate this process. This project attempted to evaluate aromatic AA metabolism during the ontogenesis of fish species with a marked (Senegalese sole; Solea senegalensis) and a less accentuated metamorphosis (gilthead seabream; Sparus aurata). Fish were tube-fed with three L-[U-14C] AA solutions at pre-metamorphic, metamorphic and post-metamorphic stages of development: controlled AA mixture (Mix), phenylalanine (Phe) and tyrosine (Tyr). Results showed a preferential aromatic AA retention during the metamorphosis of Senegalese sole, rather than in gilthead seabream. Senegalese sole's highly accentuated metamorphosis seems to increase aromatic AA physiological requirements, possibly for thyroid hormone production. Thus, Senegalese sole seems to be especially susceptible to dietary aromatic AA deficiencies during the metamorphosis period, and these findings may be important for physiologists, fish nutritionists and the flatfish aquaculture industry.

  7. Ghrelin: a metabolic signal affecting the reproductive system.

    PubMed

    Lorenzi, Teresa; Meli, Rosaria; Marzioni, Daniela; Morroni, Manrico; Baragli, Alessandra; Castellucci, Mario; Gualillo, Oreste; Muccioli, Giampiero

    2009-04-01

    Ghrelin, an acylated 28 amino acid gastric peptide, was isolated from the stomach as an endogenous ligand for growth hormone (GH) secretagogue receptor in 1999. Circulating ghrelin is mainly produced by specific cells in the stomach's oxyntic glands. Ghrelin potently stimulates GH release and food intake and exhibits diverse effects, including ones on glucose metabolism and on secretion and motility of the gastrointestinal tract. Besides these effects on food intake and energy homeostasis, ghrelin is also involved in controlling reproductive functions, and a role for it as a novel regulator of the hypothalamic-pituitary gonadal axis is clearly emerging. We review recent ghrelin research with emphasis on its roles in the reproductive axis.

  8. NITROGEN DEPOSITION AND ORGANIC MATTER MANIPULATIONS AFFECT GROSS AND NET NITROGEN TRANSFORMATIONS IN TWO TEMPERATE FORESTS SOILS

    EPA Science Inventory

    Soil nitrogen transformations are intricately linked to carbon transformations. We utilized two existing organic matter manipulation sites in western Oregon, USA and Hungary to investigate these linkages. Our questions were: 1) Does the quantity and quality of organic matter af...

  9. Genomic deletions disrupt nitrogen metabolism pathways of a cyanobacterial diatom symbiont.

    PubMed

    Hilton, Jason A; Foster, Rachel A; Tripp, H James; Carter, Brandon J; Zehr, Jonathan P; Villareal, Tracy A

    2013-01-01

    Diatoms with symbiotic N₂-fixing cyanobacteria are often abundant in the oligotrophic open ocean gyres. The most abundant cyanobacterial symbionts form heterocysts (specialized cells for N₂ fixation) and provide nitrogen (N) to their hosts, but their morphology, cellular locations and abundances differ depending on the host. Here we show that the location of the symbiont and its dependency on the host are linked to the evolution of the symbiont genome. The genome of Richelia (found inside the siliceous frustule of Hemiaulus) is reduced and lacks ammonium transporters, nitrate/nitrite reductases and glutamine:2-oxoglutarate aminotransferase. In contrast, the genome of the closely related Calothrix (found outside the frustule of Chaetoceros) is more similar to those of free-living heterocyst-forming cyanobacteria. The genome of Richelia is an example of metabolic streamlining that has implications for the evolution of N₂-fixing symbiosis and potentially for manipulating plant-cyanobacterial interactions.

  10. Modeling the role of covalent enzyme modification in Escherichia coli nitrogen metabolism

    NASA Astrophysics Data System (ADS)

    Kidd, Philip B.; Wingreen, Ned S.

    2010-03-01

    In the bacterium Escherichia coli, the enzyme glutamine synthetase (GS) converts ammonium into the amino acid glutamine. GS is principally active when the cell is experiencing nitrogen limitation, and its activity is regulated by a bicyclic covalent modification cascade. The advantages of this bicyclic-cascade architecture are poorly understood. We analyze a simple model of the GS cascade in comparison to other regulatory schemes and conclude that the bicyclic cascade is suboptimal for maintaining metabolic homeostasis of the free glutamine pool. Instead, we argue that the lag inherent in the covalent modification of GS slows the response to an ammonium shock and thereby allows GS to transiently detoxify the cell, while maintaining homeostasis over longer times.

  11. Metabolic differences in temperamental Brahman cattle can affect productivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many factors may adversely affect the growth and productivity of livestock. These include stressors associated with management practices, such as weaning, handling relative to transportation, and vaccination, that can modulate growth through the production of stress-related hormones (i.e., cortisol,...

  12. On-line modeling intracellular carbon and energy metabolism of Nannochloropsis sp. in nitrogen-repletion and nitrogen-limitation cultures.

    PubMed

    Zhang, Dongmei; Yan, Fei; Sun, Zhongliang; Zhang, Qinghua; Xue, Shengzhang; Cong, Wei

    2014-07-01

    In this study, a photobioreactor cultivation system and a calculation method for on-line monitoring of carbon and energy metabolism of microalgae were developed using Nannochloropsis sp. in nitrogen-repletion and nitrogen-limitation cultures. Only 30-60% of carbon fixed in Calvin cycle was used for biomass and the rest was lost in light respiration. The net fixed carbon was assumed to be incorporated into protein, lipids, carbohydrates, and nucleic acids, whose contents calculated on-line fitted well with the experimental measurements. Intracellular ATPs were quantitatively divided for biomass production and cell maintenance, and the result is in accordance with known reports. Due to light limitation induced by high cell concentration in batch cultures, the proportion of CO2 loss in light respiration and the proportion of energy for maintenance rapidly increased in culturing process. Nitrogen starvation reduced the light respiration, thus decreasing CO2 loss and maintenance energy, but no effect on ATP requirement for cell growth.

  13. Static magnetic field treatment of seeds improves carbon and nitrogen metabolism under salinity stress in soybean.

    PubMed

    Baghel, Lokesh; Kataria, Sunita; Guruprasad, Kadur Narayan

    2016-10-01

    The effectiveness of magnetopriming was assessed for alleviation of salt-induced adverse effects on soybean growth. Soybean seeds were pre-treated with static magnetic field (SMF) of 200 mT for 1 h to evaluate the effect of magnetopriming on growth, carbon and nitrogen metabolism, and yield of soybean plants under different salinity levels (0, 25, and 50 mM NaCl). The adverse effect of NaCl-induced salt stress was found on growth, yield, and various physiological attributes of soybeans. Results indicate that SMF pre-treatment significantly increased plant growth attributes, number of root nodules, nodules, fresh weight, biomass accumulation, and photosynthetic performance under both non-saline and saline conditions as compared to untreated seeds. Polyphasic chlorophyll a fluorescence (OJIP) transients from magnetically treated plants gave a higher fluorescence yield at J-I-P phase. Nitrate reductase activity, PIABS , photosynthetic pigments, and net rate of photosynthesis were also higher in plants that emerged from SMF pre-treated seeds as compared to untreated seeds. Leghemoglobin content and hemechrome content in root nodules were also increased by SMF pre-treatment. Thus pre-sowing exposure of seeds to SMF enhanced carbon and nitrogen metabolism and improved the yield of soybeans in terms of number of pods, number of seeds, and seed weight under saline as well as non-saline conditions. Consequently, SMF pre-treatment effectively mitigated adverse effects of NaCl on soybeans. It indicates that magnetopriming of dry soybean seeds can be effectively used as a pre-sowing treatment for alleviating salinity stress. Bioelectromagnetics. 37:455-470, 2016. © 2016 Wiley Periodicals, Inc.

  14. The mechansims by which solute nitrogen affects phase transformations and mechanical properties of automotive dual-phase sheet steel

    NASA Astrophysics Data System (ADS)

    Brown, Tyson W.

    Dual-phase steels have seen increased use in automotive applications in recent years, in order to meet the goals of weight reduction and occupant safety. Variations in nitrogen content that may be encountered in steel sourced from a basic oxygen furnace process compared to an electric arc furnace process require that dual-phase steel producers understand the ways that nitrogen affects processing and properties. In the current work, the distribution of nitrogen was investigated in a dual-phase steel with a base chemistry of 0.1 C, 2.0 Mn, 0.2 Cr, 0.2 Mo (wt pct) across a range of nitrogen contents (30-159 ppm) with Al (0.2 and 0.08 wt pct), and Ti (0.02 wt pct) additions used for precipitation control of nitrogen amounts. The distribution of nitrogen amongst trapping sites, including precipitates, grain boundaries, dislocations, and interstitial sites (away from other types of defects) was determined from a combination of electrolytic dissolution, internal friction, and three-dimensional atom probe tomography experiments. Various mechanisms by which different amounts and locations of nitrogen affect phase transformations and mechanical properties were identified from quantitative metallography, dilatometric measurement of phase transformations, tensile testing, and nanoindentation hardness testing. Results indicate nitrogen that is not precipitated with Ti or Al (free nitrogen) partitions to austenite (and thus martensite) during typical intercritical annealing treatments, and is mostly contained in Cottrell atmospheres in martensite. Due to the austenite stabilizing effect of nitrogen, the presence of free nitrogen during intercritical annealing leads to a higher austenite fraction in certain conditions. Thus, the presence of free nitrogen in a dual-phase microstructure will lead to an increase in tensile and yield strengths from both an increase in martensite fraction, and an increase in martensite hardness due to solid solution strengthening. Despite the presence

  15. Metagenomic analysis of nitrogen metabolism genes in the surface of marine sediments

    NASA Astrophysics Data System (ADS)

    Reyes, Carolina; Schneider, Dominik; Thürmer, Andrea; Dellwig, Olaf; Lipka, Marko; Daniel, Rolf; Böttcher, Michael E.; Friedrich, Michael W.

    2016-04-01

    In this study, we analysed metagenomes along with biogeochemical profiles from Skagerrak (North Sea) and Bothnian Bay (Baltic Sea) sediments, to trace the prevailing nitrogen pathways. NO3- was present in the top 5 cm below the sediment-water interface at both sites. NH4+ increased with depth below 5 cm where it overlapped with the NO3- zone. Steady state modelling of NO3- and NH4+ porewater profiles indicates zones of net nitrogen species transformations. Protease, peptidase, urease and deaminase ammonification genes were detected in metagenomes. Genes involved in ammonia oxidation (amo, hao), nitrite oxidation (nxr), denitrification (nar, nir, nor) and dissimilatory NO3- reduction to NH4+ (nap, nfr and otr) were also present. 16S rRNA gene analysis showed that the nitrifying group Nitrosopumilales and other groups involved in nitrification and denitrification (Nitrobacter, Nitrosomonas, Nitrospira, Nitrosococcus, and Nitrosonomas) appeared less abundant in Skagerrak sediments compared to Bothnian Bay sediments. Beggiatoa and Thiothrix 16S rRNA genes were also present suggesting chemolithoautotrophic NO3- reduction to NO2- or NH4+ as a possible pathway. Although anammox planctomycetes 16S rRNA genes were present in metagenomes, anammox protein-coding genes were not detected. Our results show the metabolic potential for ammonification, nitrification, NO3- reduction, and denitrification activities in Skagerrak and Bothnian Bay sediments.

  16. [Metabolic studies in brothers affected by alcaptonuria (ochronosis)].

    PubMed

    Pugge, H R; Orozco, M; Toledo, A; Ripoll, J; Katz, J; Toledo, I; Pellanda, R

    1978-01-01

    The case of two brothers affected by alcaptonurie is reported. The activity of the homogenthisycasa enzyme has been determined by the material obtained through percutaneous biopsy. Concentrations of the aminoacids producing fenilalanina and thiroxina in their parents' blood have been investigated, the tests showing lack of liver enzyme and normal concentration of the amount of aminoacids in blood. Some aspects of skin lesion have been briefly reported and methods for treatment presented.

  17. Loading-induced changes in synovial fluid affect cartilage metabolism.

    PubMed

    Van den Hoogen, B M; van de Lest, C H; van Weeren, P R; Lafeber, F P; Lopes-Cardozo, M; van Golde, L M; Barneveld, A

    1998-06-01

    The purpose of this study was to determine whether changes in the synovial fluid (SF) induced by in vivo loading can induce an alteration in the metabolic activity of chondrocytes in vitro. Therefore, SF was collected from ponies after a period of box rest and after they had exercise for a week. Normal, unloaded articular cartilage explants were cultured in 20% solutions of these SFs for 4 days and chondrocyte activity was determined by glycosaminoglycan (GAG) turnover. In explants cultured in post-exercise SF, GAG synthesis was enhanced and GAG release was diminished when compared to cultures in pre-exercise SF. SF analysis showed that levels of insulin-like growth factors (IGF-I and IGF-II) tended to be higher in post-exercise SF, while no differences were found in metalloproteinase activity, hyaluronic acid and protein concentrations. This study showed that anabolic effects of joint loading on cartilage are, at least partially, mediated by alterations in the SF.

  18. Effect of water stress and foliar boron application on seed protein oil fatty acids and nitrogen metabolism in soybean

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of water stress and foliar boron (FB) application on soybean (Glycine max (L) Merr.) seed composition and nitrogen metabolism have not been well investigated. Therefore, the objective of this study was to investigate the effects of water stress and FB on seed protein, oil, fatty acids, nitra...

  19. Genome-wide association study of carbon and nitrogen metabolism in the maize nested association mapping population

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Carbon (C) and nitrogen (N) metabolism are critical to plant growth and development and at the basis of yield and adaptation. We have applied high throughput metabolite analyses to over 12,000 diverse field grown samples from the maize nested association mapping population. This allowed us to identi...

  20. Predicting nitrogen loading with land-cover composition: how can watershed size affect model performance?

    PubMed

    Zhang, Tao; Yang, Xiaojun

    2013-01-01

    Watershed-wide land-cover proportions can be used to predict the in-stream non-point source pollutant loadings through regression modeling. However, the model performance can vary greatly across different study sites and among various watersheds. Existing literature has shown that this type of regression modeling tends to perform better for large watersheds than for small ones, and that such a performance variation has been largely linked with different interwatershed landscape heterogeneity levels. The purpose of this study is to further examine the previously mentioned empirical observation based on a set of watersheds in the northern part of Georgia (USA) to explore the underlying causes of the variation in model performance. Through the combined use of the neutral landscape modeling approach and a spatially explicit nutrient loading model, we tested whether the regression model performance variation over the watershed groups ranging in size is due to the different watershed landscape heterogeneity levels. We adopted three neutral landscape modeling criteria that were tied with different similarity levels in watershed landscape properties and used the nutrient loading model to estimate the nitrogen loads for these neutral watersheds. Then we compared the regression model performance for the real and neutral landscape scenarios, respectively. We found that watershed size can affect the regression model performance both directly and indirectly. Along with the indirect effect through interwatershed heterogeneity, watershed size can directly affect the model performance over the watersheds varying in size. We also found that the regression model performance can be more significantly affected by other physiographic properties shaping nitrogen delivery effectiveness than the watershed land-cover heterogeneity. This study contrasts with many existing studies because it goes beyond hypothesis formulation based on empirical observations and into hypothesis testing to

  1. Nitrate and Ammonium Contribute to the Distinct Nitrogen Metabolism of Populus simonii during Moderate Salt Stress

    PubMed Central

    Meng, Sen; Su, Li; Li, Yiming; Wang, Yinjuan; Zhang, Chunxia; Zhao, Zhong

    2016-01-01

    Soil salinity is a major abiotic stressor affecting plant growth. Salinity affects nitrification and ammonification in the soil, however, limited information is available on the influence of different N sources on N metabolism during salt stress. To understand the N metabolism changes in response to different N sources during moderate salt stress, we investigated N uptake, assimilation and the transcript abundance of associated genes in Populus simonii seedlings treated with moderate salt stress (75mM NaCl) under hydroponic culture conditions with nitrate (NO3-) or ammonium (NH4+). Salt stress negatively affected plant growth in both NH4+-fed and NO3--fed plants. Both NH4+ uptake and the total N concentration were significantly increased in the roots of the NH4+-fed plants during salt stress. However, the NO3- uptake and nitrate reductase (NR) and nitrite reductase (NiR) activity primarily depended on the NO3- supply and was not influenced by salt stress. Salt stress decreased glutamine synthetase (GS) and glutamate synthase (GOGAT) activity in the roots and leaves. Most genes associated with NO3-uptake, reduction and N metabolism were down-regulated or remained unchanged; while two NH4+ transporter genes closely associated with NH4+ uptake (AMT1;2 and AMT1;6) were up-regulated in response to salt stress in the NH4+-fed plants. The accumulation of different amino acid compounds was observed in the NH4+- and NO3-- fed plants during salt treatment. The results suggested that N metabolism in P. simonii plants exposed to salt enhanced salt resistance in the plants that were fed with NO3- instead of NH4+ as the sole N source. PMID:26950941

  2. Nitrogen

    USGS Publications Warehouse

    Apodaca, L.E.

    2012-01-01

    Ammonia was produced by 12 companies at 27 plants in 15 states in the United States during 2011. Sixty-one percent of total U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of those states' large reserves of natural gas, the dominant domestic feedstock. In 2011, U.S. producers operated at about 84 percent of their rated capacity (excluding plants that were idle for the entire year). Four companies — CF Industries Holdings Inc.; Koch Nitrogen Co.; PCS Nitrogen Inc. and Agrium Inc., in descending order — accounted for 77 percent of the total U.S. ammonia production capacity.

  3. Comparison of environmental and isolate Sulfobacillus genomes reveals diverse carbon, sulfur, nitrogen, and hydrogen metabolisms

    SciTech Connect

    Justice, Nicholas B.; Norman, Anders; Brown, Christopher T.; Singh, Andrea; Thomas, Brian C.; Banfield, Jillian F.

    2014-12-15

    Bacteria of the genus Sulfobacillus are found worldwide as members of microbial communities that accelerate sulfide mineral dissolution in acid mine drainage environments (AMD), acid-rock drainage environments (ARD), as well as in industrial bioleaching operations. Despite their frequent identification in these environments, their role in biogeochemical cycling is poorly understood. Here we report draft genomes of five species of the Sulfobacillus genus (AMDSBA1-5) reconstructed by cultivation-independent sequencing of biofilms sampled from the Richmond Mine (Iron Mountain, CA). Three of these species (AMDSBA2, AMDSBA3, and AMDSBA4) have no cultured representatives while AMDSBA1 is a strain of S. benefaciens, and AMDSBA5 a strain of S. thermosulfidooxidans. We analyzed the diversity of energy conservation and central carbon metabolisms for these genomes and previously published Sulfobacillus genomes. Pathways of sulfur oxidation vary considerably across the genus, including the number and type of subunits of putative heterodisulfide reductase complexes likely involved in sulfur oxidation. The number and type of nickel-iron hydrogenase proteins varied across the genus, as does the presence of different central carbon pathways. Only the AMDSBA3 genome encodes a dissimilatory nitrate reducatase and only the AMDSBA5 and S. thermosulfidooxidans genomes encode assimilatory nitrate reductases. Lastly, within the genus, AMDSBA4 is unusual in that its electron transport chain includes a cytochrome bc type complex, a unique cytochrome c oxidase, and two distinct succinate dehydrogenase complexes. Overall, the results significantly expand our understanding of carbon, sulfur, nitrogen, and hydrogen metabolism within the Sulfobacillus genus.

  4. Local inhibition of nitrogen fixation and nodule metabolism in drought-stressed soybean

    PubMed Central

    Gil-Quintana, Erena; Larrainzar, Estíbaliz; Seminario, Amaia; Díaz-Leal, Juan Luis; Alamillo, Josefa M.; Pineda, Manuel; Arrese-Igor, Cesar; Wienkoop, Stefanie; González, Esther M.

    2013-01-01

    Drought stress is a major factor limiting symbiotic nitrogen fixation (NF) in soybean crop production. However, the regulatory mechanisms involved in this inhibition are still controversial. Soybean plants were symbiotically grown in a split-root system (SRS), which allowed for half of the root system to be irrigated at field capacity while the other half remained water deprived. NF declined in the water-deprived root system while nitrogenase activity was maintained at control values in the well-watered half. Concomitantly, amino acids and ureides accumulated in the water-deprived belowground organs regardless of transpiration rates. Ureide accumulation was found to be related to the decline in their degradation activities rather than increased biosynthesis. Finally, proteomic analysis suggests that plant carbon metabolism, protein synthesis, amino acid metabolism, and cell growth are among the processes most altered in soybean nodules under drought stress. Results presented here support the hypothesis of a local regulation of NF taking place in soybean and downplay the role of ureides in the inhibition of NF. PMID:23580751

  5. Unusual respiratory capacity and nitrogen metabolism in a Parcubacterium (OD1) of the Candidate Phyla Radiation

    PubMed Central

    Castelle, Cindy J.; Brown, Christopher T.; Thomas, Brian C.; Williams, Kenneth H.; Banfield, Jillian F.

    2017-01-01

    The Candidate Phyla Radiation (CPR) is a large group of bacteria, the scale of which approaches that of all other bacteria. CPR organisms are inferred to depend on other community members for many basic cellular building blocks and all appear to be obligate anaerobes. To date, there has been no evidence for any significant respiratory capacity in an organism from this radiation. Here we report a curated draft genome for ‘Candidatus Parcunitrobacter nitroensis’ a member of the Parcubacteria (OD1) superphylum of the CPR. The genome encodes versatile energy pathways, including fermentative and respiratory capacities, nitrogen and fatty acid metabolism, as well as the first complete electron transport chain described for a member of the CPR. The sequences of all of these enzymes are highly divergent from sequences found in other organisms, suggesting that these capacities were not recently acquired from non-CPR organisms. Although the wide respiration-based repertoire points to a different lifestyle compared to other CPR bacteria, we predict similar obligate dependence on other organisms or the microbial community. The results substantially expand the known metabolic potential of CPR bacteria, although sequence comparisons indicate that these capacities are very rare in members of this radiation. PMID:28067254

  6. Changes in transcript abundance in Chlamydomonas reinhardtii following nitrogen deprivation predict diversion of metabolism.

    PubMed

    Miller, Rachel; Wu, Guangxi; Deshpande, Rahul R; Vieler, Astrid; Gärtner, Katrin; Li, Xiaobo; Moellering, Eric R; Zäuner, Simone; Cornish, Adam J; Liu, Bensheng; Bullard, Blair; Sears, Barbara B; Kuo, Min-Hao; Hegg, Eric L; Shachar-Hill, Yair; Shiu, Shin-Han; Benning, Christoph

    2010-12-01

    Like many microalgae, Chlamydomonas reinhardtii forms lipid droplets rich in triacylglycerols when nutrient deprived. To begin studying the mechanisms underlying this process, nitrogen (N) deprivation was used to induce triacylglycerol accumulation and changes in developmental programs such as gametogenesis. Comparative global analysis of transcripts under induced and noninduced conditions was applied as a first approach to studying molecular changes that promote or accompany triacylglycerol accumulation in cells encountering a new nutrient environment. Towards this goal, high-throughput sequencing technology was employed to generate large numbers of expressed sequence tags of eight biologically independent libraries, four for each condition, N replete and N deprived, allowing a statistically sound comparison of expression levels under the two tested conditions. As expected, N deprivation activated a subset of control genes involved in gametogenesis while down-regulating protein biosynthesis. Genes for components of photosynthesis were also down-regulated, with the exception of the PSBS gene. N deprivation led to a marked redirection of metabolism: the primary carbon source, acetate, was no longer converted to cell building blocks by the glyoxylate cycle and gluconeogenesis but funneled directly into fatty acid biosynthesis. Additional fatty acids may be produced by membrane remodeling, a process that is suggested by the changes observed in transcript abundance of putative lipase genes. Inferences on metabolism based on transcriptional analysis are indirect, but biochemical experiments supported some of these deductions. The data provided here represent a rich source for the exploration of the mechanism of oil accumulation in microalgae.

  7. Sitona lineatus (Coleoptera: Curculionidae) Larval Feeding on Pisum sativum L. Affects Soil and Plant Nitrogen.

    PubMed

    Cárcamo, Héctor A; Herle, Carolyn E; Lupwayi, Newton Z

    2015-01-01

    Adults of Sitona lineatus (pea leaf weevil, PLW) feed on foliage of several Fabaceae species but larvae prefer to feed on nodules of Pisum sativum L. and Vicia faba L. Indirectly, through their feeding on rhizobia, weevils can reduce soil and plant available nitrogen (N). However, initial soil N can reduce nodulation and damage by the weevil and reduce control requirements. Understanding these interactions is necessary to make integrated pest management recommendations for PLW. We conducted a greenhouse study to quantify nodulation, soil and plant N content, and nodule damage by weevil larvae in relation to soil N amendment with urea, thiamethoxam insecticide seed coating and crop stage. PLWs reduced the number of older tumescent (multilobed) nodules and thiamethoxam addition increased them regardless of other factors. Nitrogen amendment significantly increased soil available N (>99% nitrate) as expected and PLW presence was associated with significantly lower levels of soil N. PLW decreased plant N content at early flower and thiamethoxam increased it, particularly at late flower. The study illustrated the complexity of interactions that determine insect herbivory effects on plant and soil nutrition for invertebrates that feed on N-fixing root nodules. We conclude that effects of PLW on nodulation and subsequent effects on plant nitrogen are more pronounced during the early growth stages of the plant. This suggests the importance of timing of PLW infestation and may explain the lack of yield depression in relation to this pest observed in many field studies. Also, pea crops in soils with high levels of soil N are unlikely to be affected by this herbivore and should not require insecticide inputs.

  8. Sitona lineatus (Coleoptera: Curculionidae) Larval Feeding on Pisum sativum L. Affects Soil and Plant Nitrogen

    PubMed Central

    Cárcamo, Héctor A.; Herle, Carolyn E.; Lupwayi, Newton Z.

    2015-01-01

    Adults of Sitona lineatus (pea leaf weevil, PLW) feed on foliage of several Fabaceae species but larvae prefer to feed on nodules of Pisum sativum L. and Vicia faba L. Indirectly, through their feeding on rhizobia, weevils can reduce soil and plant available nitrogen (N). However, initial soil N can reduce nodulation and damage by the weevil and reduce control requirements. Understanding these interactions is necessary to make integrated pest management recommendations for PLW. We conducted a greenhouse study to quantify nodulation, soil and plant N content, and nodule damage by weevil larvae in relation to soil N amendment with urea, thiamethoxam insecticide seed coating and crop stage. PLWs reduced the number of older tumescent (multilobed) nodules and thiamethoxam addition increased them regardless of other factors. Nitrogen amendment significantly increased soil available N (>99% nitrate) as expected and PLW presence was associated with significantly lower levels of soil N. PLW decreased plant N content at early flower and thiamethoxam increased it, particularly at late flower. The study illustrated the complexity of interactions that determine insect herbivory effects on plant and soil nutrition for invertebrates that feed on N-fixing root nodules. We conclude that effects of PLW on nodulation and subsequent effects on plant nitrogen are more pronounced during the early growth stages of the plant. This suggests the importance of timing of PLW infestation and may explain the lack of yield depression in relation to this pest observed in many field studies. Also, pea crops in soils with high levels of soil N are unlikely to be affected by this herbivore and should not require insecticide inputs. PMID:26106086

  9. Childhood obesity affects adult metabolic syndrome and diabetes.

    PubMed

    Liang, Yajun; Hou, Dongqing; Zhao, Xiaoyuan; Wang, Liang; Hu, Yuehua; Liu, Junting; Cheng, Hong; Yang, Ping; Shan, Xinying; Yan, Yinkun; Cruickshank, J Kennedy; Mi, Jie

    2015-09-01

    We seek to observe the association between childhood obesity by different measures and adult obesity, metabolic syndrome (MetS), and diabetes. Thousand two hundred and nine subjects from "Beijing Blood Pressure Cohort Study" were followed 22.9 ± 0.5 years in average from childhood to adulthood. We defined childhood obesity using body mass index (BMI) or left subscapular skinfold (LSSF), and adult obesity as BMI ≥ 28 kg/m(2). MetS was defined according to the joint statement of International Diabetes Federation and American Heart Association with modified waist circumference (≥ 90/85 cm for men/women). Diabetes was defined as fasting plasma glucose ≥ 7.0 mmol/L or blood glucose 2 h after oral glucose tolerance test ≥ 11.1 mmol/L or currently using blood glucose-lowering agents. Multiple linear and logistic regression models were used to assess the association. The incidence of adult obesity was 13.4, 60.0, 48.3, and 65.1 % for children without obesity, having obesity by BMI only, by LSSF only, and by both, respectively. Compared to children without obesity, children obese by LSSF only or by both had higher risk of diabetes. After controlling for adult obesity, childhood obesity predicted independently long-term risks of diabetes (odds ratio 2.8, 95 % confidence interval 1.2-6.3) or abdominal obesity (2.7, 1.6-4.7) other than MetS as a whole (1.2, 0.6-2.4). Childhood obesity predicts long-term risk of adult diabetes, and the effect is independent of adult obesity. LSSF is better than BMI in predicting adult diabetes.

  10. METABOLIC ENGINEERING TO DEVELOP A PATHWAY FOR THE SELECTIVE CLEAVAGE OF CARBON-NITROGEN BONDS

    SciTech Connect

    John J. Kilbane III

    2003-12-01

    . The construction of a new metabolic pathway to selectively remove nitrogen from carbazole and other molecules typically found in petroleum should lead to the development of a process to improve oil refinery efficiency by reducing the poisoning, by nitrogen, of catalysts used in the hydrotreating and catalytic cracking of petroleum.

  11. Microbial metabolic potential for carbon degradation and nutrient (nitrogen and phosphorus) acquisition in an ombrotrophic peatland.

    PubMed

    Lin, Xueju; Tfaily, Malak M; Green, Stefan J; Steinweg, J Megan; Chanton, Patrick; Imvittaya, Aopeau; Chanton, Jeffrey P; Cooper, William; Schadt, Christopher; Kostka, Joel E

    2014-06-01

    This study integrated metagenomic and nuclear magnetic resonance (NMR) spectroscopic approaches to investigate microbial metabolic potential for organic matter decomposition and nitrogen (N) and phosphorus (P) acquisition in soils of an ombrotrophic peatland in the Marcell Experimental Forest (MEF), Minnesota, USA. This analysis revealed vertical stratification in key enzymatic pathways and taxa containing these pathways. Metagenomic analyses revealed that genes encoding laccases and dioxygenases, involved in aromatic compound degradation, declined in relative abundance with depth, while the relative abundance of genes encoding metabolism of amino sugars and all four saccharide groups increased with depth in parallel with a 50% reduction in carbohydrate content. Most Cu-oxidases were closely related to genes from Proteobacteria and Acidobacteria, and type 4 laccase-like Cu-oxidase genes were >8 times more abundant than type 3 genes, suggesting an important and overlooked role for type 4 Cu-oxidase in phenolic compound degradation. Genes associated with sulfate reduction and methanogenesis were the most abundant anaerobic respiration genes in these systems, with low levels of detection observed for genes of denitrification and Fe(III) reduction. Fermentation genes increased in relative abundance with depth and were largely affiliated with Syntrophobacter. Methylocystaceae-like small-subunit (SSU) rRNA genes, pmoA, and mmoX genes were more abundant among methanotrophs. Genes encoding N2 fixation, P uptake, and P regulons were significantly enriched in the surface peat and in comparison to other ecosystems, indicating N and P limitation. Persistence of inorganic orthophosphate throughout the peat profile in this P-limiting environment indicates that P may be bound to recalcitrant organic compounds, thus limiting P bioavailability in the subsurface. Comparative metagenomic analysis revealed a high metabolic potential for P transport and starvation, N2 fixation, and

  12. Microbial Metabolic Potential for Carbon Degradation and Nutrient (Nitrogen and Phosphorus) Acquisition in an Ombrotrophic Peatland

    PubMed Central

    Tfaily, Malak M.; Green, Stefan J.; Steinweg, J. Megan; Chanton, Patrick; Imvittaya, Aopeau; Chanton, Jeffrey P.; Cooper, William; Schadt, Christopher

    2014-01-01

    This study integrated metagenomic and nuclear magnetic resonance (NMR) spectroscopic approaches to investigate microbial metabolic potential for organic matter decomposition and nitrogen (N) and phosphorus (P) acquisition in soils of an ombrotrophic peatland in the Marcell Experimental Forest (MEF), Minnesota, USA. This analysis revealed vertical stratification in key enzymatic pathways and taxa containing these pathways. Metagenomic analyses revealed that genes encoding laccases and dioxygenases, involved in aromatic compound degradation, declined in relative abundance with depth, while the relative abundance of genes encoding metabolism of amino sugars and all four saccharide groups increased with depth in parallel with a 50% reduction in carbohydrate content. Most Cu-oxidases were closely related to genes from Proteobacteria and Acidobacteria, and type 4 laccase-like Cu-oxidase genes were >8 times more abundant than type 3 genes, suggesting an important and overlooked role for type 4 Cu-oxidase in phenolic compound degradation. Genes associated with sulfate reduction and methanogenesis were the most abundant anaerobic respiration genes in these systems, with low levels of detection observed for genes of denitrification and Fe(III) reduction. Fermentation genes increased in relative abundance with depth and were largely affiliated with Syntrophobacter. Methylocystaceae-like small-subunit (SSU) rRNA genes, pmoA, and mmoX genes were more abundant among methanotrophs. Genes encoding N2 fixation, P uptake, and P regulons were significantly enriched in the surface peat and in comparison to other ecosystems, indicating N and P limitation. Persistence of inorganic orthophosphate throughout the peat profile in this P-limiting environment indicates that P may be bound to recalcitrant organic compounds, thus limiting P bioavailability in the subsurface. Comparative metagenomic analysis revealed a high metabolic potential for P transport and starvation, N2 fixation, and

  13. Effects of urban stream burial on nitrogen uptake and ecosystem metabolism: implications for watershed nitrogen and carbon fluxes

    EPA Science Inventory

    Urbanization has resulted in extensive burial and channelization of headwater streams, yet little is known about impacts on stream ecosystem functions critical for reducing downstream nitrogen pollution. To characterize the biogeochemical impact of stream burial, we measured NO3...

  14. Sonoran Desert winter annuals affected by density of red brome and soil nitrogen

    USGS Publications Warehouse

    Salo, L.F.; McPherson, G.R.; Williams, D.G.

    2005-01-01

    Red brome [Bromus madritensis subsp. rubens (L.) Husn.] is a Mediterranean winter annual grass that has invaded Southwestern USA deserts. This study evaluated interactions among 13 Sonoran Desert annual species at four densities of red brome from 0 to the equivalent of 1200 plants ma??2. We examined these interactions at low (3 I?g) and high (537 I?g NO3a?? g soila??1) nitrogen (N) to evaluate the relative effects of soil N level on survival and growth of native annuals and red brome. Red brome did not affect emergence or survival of native annuals, but significantly reduced growth of natives, raising concerns about effects of this exotic grass on the fecundity of these species. Differences in growth of red brome and of the three dominant non nitrogen-fixing native annuals at the two levels of soil N were similar. Total species biomass of red brome was reduced by 83% at low, compared to high, N levels, whereas that of the three native species was reduced by from 42 to 95%. Mean individual biomass of red brome was reduced by 87% at low, compared to high, N levels, whereas that of the three native species was reduced by from 72 to 89%.

  15. Metabolic and transcriptional response of central metabolism affected by root endophytic fungus Piriformospora indica under salinity in barley.

    PubMed

    Ghaffari, Mohammad Reza; Ghabooli, Mehdi; Khatabi, Behnam; Hajirezaei, Mohammad Reza; Schweizer, Patrick; Salekdeh, Ghasem Hosseini

    2016-04-01

    The root endophytic fungus Piriformospora indica enhances plant adaptation to environmental stress based on general and non-specific plant species mechanisms. In the present study, we integrated the ionomics, metabolomics, and transcriptomics data to identify the genes and metabolic regulatory networks conferring salt tolerance in P. indica-colonized barley plants. To this end, leaf samples were harvested at control (0 mM NaCl) and severe salt stress (300 mM NaCl) in P. indica-colonized and non-inoculated barley plants 4 weeks after fungal inoculation. The metabolome analysis resulted in an identification of a signature containing 14 metabolites and ions conferring tolerance to salt stress. Gene expression analysis has led to the identification of 254 differentially expressed genes at 0 mM NaCl and 391 genes at 300 mM NaCl in P. indica-colonized compared to non-inoculated samples. The integration of metabolome and transcriptome analysis indicated that the major and minor carbohydrate metabolism, nitrogen metabolism, and ethylene biosynthesis pathway might play a role in systemic salt-tolerance in leaf tissue induced by the root-colonized fungus.

  16. Lactobacillus acidophilus NCFM affects vitamin E acetate metabolism and intestinal bile acid signature in monocolonized mice.

    PubMed

    Roager, Henrik M; Sulek, Karolina; Skov, Kasper; Frandsen, Henrik L; Smedsgaard, Jørn; Wilcks, Andrea; Skov, Thomas H; Villas-Boas, Silas G; Licht, Tine R

    2014-01-01

    Monocolonization of germ-free (GF) mice enables the study of specific bacterial species in vivo. Lactobacillus acidophilus NCFM(TM) (NCFM) is a probiotic strain; however, many of the mechanisms behind its health-promoting effect remain unknown. Here, we studied the effects of NCFM on the metabolome of jejunum, cecum, and colon of NCFM monocolonized (MC) and GF mice using liquid chromatography coupled to mass-spectrometry (LC-MS). The study adds to existing evidence that NCFM in vivo affects the bile acid signature of mice, in particular by deconjugation. Furthermore, we confirmed that carbohydrate metabolism is affected by NCFM in the mouse intestine as especially the digestion of oligosaccharides (penta- and tetrasaccharides) was increased in MC mice. Additionally, levels of α-tocopherol acetate (vitamin E acetate) were higher in the intestine of GF mice than in MC mice, suggesting that NCFM affects the vitamin E acetate metabolism. NCFM did not digest vitamin E acetate in vitro, suggesting that direct bacterial metabolism was not the cause of the altered metabolome in vivo. Taken together, our results suggest that NCFM affects intestinal carbohydrate metabolism, bile acid metabolism and vitamin E metabolism, although it remains to be investigated whether this effect is unique to NCFM.

  17. Targeting MUC1-Mediated Tumor-Stromal Metabolic Interaction in Triple-Negative Breast Cancer

    DTIC Science & Technology

    2016-11-01

    significant enrichment of multiple pathways. Figs 2-3 identify the top 10 affected pathways, ordered by impact factor. Nitrogen metabolism and Aminoacyl...biosynthesis, D-Glutamine and D-glutamate metabolism, Nicotinate and nicotinamide metabolism, and Nitrogen metabolism were amongst the redundant...pathways identified in MDA- MB-468 (Fig 3). Nitrogen metabolism and D-Glutamine and D-glutamate metabolism pathways were filtered out as potential

  18. PII Overexpression in Lotus japonicus Affects Nodule Activity in Permissive Low-Nitrogen Conditions and Increases Nodule Numbers in High Nitrogen Treated Plants.

    PubMed

    D'Apuzzo, Enrica; Valkov, Vladimir Totev; Parlati, Aurora; Omrane, Selim; Barbulova, Ani; Sainz, Maria Martha; Lentini, Marco; Esposito, Sergio; Rogato, Alessandra; Chiurazzi, Maurizio

    2015-04-01

    We report here the first characterization of a GLNB1 gene coding for the PII protein in leguminous plants. The main purpose of this work was the investigation of the possible roles played by this multifunctional protein in nodulation pathways. The Lotus japonicus LjGLB1 gene shows a significant transcriptional regulation during the light-dark cycle and different nitrogen availability, conditions that strongly affect nodule formation, development, and functioning. We also report analysis of the spatial profile of expression of LjGLB1 in root and nodule tissues and of the protein's subcellular localization. Transgenic L. japonicus lines overexpressing the PII protein were obtained and tested for the analysis of the symbiotic responses in different conditions. The uncoupling of PII from its native regulation affects nitrogenase activity and nodule polyamine content. Furthermore, our results suggest the involvement of PII in the signaling of the nitrogen nutritional status affecting the legumes' predisposition for nodule formation.

  19. The reallocation of carbon in P deficient lupins affects biological nitrogen fixation.

    PubMed

    Kleinert, Aleysia; Venter, Mauritz; Kossmann, Jens; Valentine, Alexander

    2014-11-01

    It is not known how phosphate (P) deficiency affects the allocation of carbon (C) to biological nitrogen fixation (BNF) in legumes. The alteration of the respiratory and photosynthetic C costs of BNF was investigated under P deficiency. Although BNF can impose considerable sink stimulation on host respiratory and photosynthetic C, it is not known how the change in the C and energy allocation during P deficiency may affect BNF. Nodulated Lupinus luteus plants were grown in sand culture, using a modified Long Ashton nutrient solution containing no nitrogen (N) for ca. four weeks, after which one set was exposed to a P-deficient nutrient medium, while the other set continued growing on a P-sufficient nutrient medium. Phosphorus stress was measured at 20 days after onset of P-starvation. During P stress the decline in nodular P levels was associated with lower BNF and nodule growth. There was also a shift in the balance of photosynthetic and respiratory C toward a loss of C during P stress. Below-ground respiration declined under limiting P conditions. However, during this decline there was also a shift in the proportion of respiratory energy from maintenance toward growth respiration. Under P stress, there was an increased allocation of C toward root growth, thereby decreasing the amount of C available for maintenance respiration. It is therefore possible that the decline in BNF under P deficiency may be due to this change in resource allocation away from respiration associated with direct nutrient uptake, but rather toward a long term nutrient acquisition strategy of increased root growth.

  20. Compost may affect volatile and semi-volatile plant emissions through nitrogen supply and chlorophyll fluorescence.

    PubMed

    Ormeño, Elena; Olivier, Romain; Mévy, Jean Philippe; Baldy, Virginie; Fernandez, Catherine

    2009-09-01

    The use of composted biosolids as an amendment for forest regeneration in degraded ecosystems is growing since sewage-sludge dumping has been banned in the European Community. Its consequences on plant terpenes are however unknown. Terpene emissions of both Rosmarinus officinalis (a terpene-storing species) and Quercus coccifera (a non-storing species) and terpene content of the former, were studied after a middle-term exposure to compost at intermediate (50tha(-1): D50) and high (100tha(-1): D100) compost rates, in a seven-year-old post-fire shrubland ecosystem. Some chlorophyll fluorescence parameters (Fv/Fm, ETR, Phi(PSII)), soil and plant enrichment in phosphorus (P) and nitrogen (N) were monitored simultaneously in amended and non-amended plots in order to establish what factors were responsible for possible compost effect on terpenes. Compost affected all studied parameters with the exception of Fv/Fm and terpene content. For both species, mono- and sesquiterpene basal emissions were intensified solely under D50 plots. On the contrary leaf P, leaf N levels reached in D50 were partly responsible of terpene changes, suggesting that optimal N conditions occurred therein. N also affected ETR and Phi(PSII) which were, in turn, robustly correlated to terpene emissions. These results imply that emissions of terpene-storing and non-storing species were under nitrogen and chlorophyll fluorescence control, and that a correct management of compost rates applied on soil may modify terpene emission rate of plants, which in turn has consequences in air quality and plant defense mechanisms.

  1. Growth-promoting nitrogen nutrition affects flavonoid biosynthesis in young apple (Malus domestica Borkh.) leaves.

    PubMed

    Strissel, T; Halbwirth, H; Hoyer, U; Zistler, C; Stich, K; Treutter, D

    2005-11-01

    Enhanced shoot growth and a decrease in flavonoid concentration in apple trees grown under high nitrogen (N) supply was observed in previous studies, along with increasing scab susceptibility of cultivar "Golden Delicious" after high N nutrition. Several hypotheses have suggested that there is a trade-off between primary and secondary metabolism because of competition for common substrates, but nothing is known about regulation at the enzyme level. In this study, a set of experiments was performed to elucidate the effect of N nutrition on the activities of key enzymes involved in flavonoid biosynthesis (phenylalanine ammonia-lyase [PAL], chalcone synthase/chalcone isomerase [CHS/CHI}, flavanone 3-hydroxylase [FHT], flavonol synthase [FLS], dihydroflavonol 4-reductase [DFR]) and the accumulation of different groups of phenylpropanoids. The inhibition of flavonoid accumulation by high N nutrition could be confirmed, but the influence of N supply on the flavonoid enzymes CHS/CHI, FHT, DFR, and FLS was not evident. However, PAL activity seems to be downregulated, thus forming a bottleneck resulting in a generally decreased flavonoid accumulation. Furthermore, the response of the scab-resistant cultivar "Rewena" to high N nutrition was not as strong as that of the susceptible cultivar "Golden Delicious".

  2. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2007-01-01

    Ammonia was produced by 15 companies at 25 plants in 16 states in the United States during 2006. Fifty-seven percent of U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas, the dominant domestic feedstock. In 2006, U.S. producers operated at about 72 percent of their rated capacity (excluding plants that were idle for the entire year). Five companies, Koch Nitrogen, Terra Industries, CF Industries, PCS Nitro-gen, and Agrium, in descending order, accounted for 79 percent U.S. ammonia production capacity. The United States was the world's fourth-ranked ammonia producer and consumer following China, India and Russia. Urea, ammonium nitrate, ammonium phosphates, nitric acid and ammonium sulfate were the major derivatives of ammonia in the United States, in descending order of importance.

  3. Plastidial Glycolytic Glyceraldehyde-3-Phosphate Dehydrogenase Is an Important Determinant in the Carbon and Nitrogen Metabolism of Heterotrophic Cells in Arabidopsis.

    PubMed

    Anoman, Armand D; Muñoz-Bertomeu, Jesús; Rosa-Téllez, Sara; Flores-Tornero, María; Serrano, Ramón; Bueso, Eduardo; Fernie, Alisdair R; Segura, Juan; Ros, Roc

    2015-11-01

    This study functionally characterizes the Arabidopsis (Arabidopsis thaliana) plastidial glycolytic isoforms of glyceraldehyde-3-phosphate dehydrogenase (GAPCp) in photosynthetic and heterotrophic cells. We expressed the enzyme in gapcp double mutants (gapcp1gapcp2) under the control of photosynthetic (Rubisco small subunit RBCS2B [RBCS]) or heterotrophic (phosphate transporter PHT1.2 [PHT]) cell-specific promoters. Expression of GAPCp1 under the control of RBCS in gapcp1gapcp2 had no significant effect on the metabolite profile or growth in the aerial part (AP). GAPCp1 expression under the control of the PHT promoter clearly affected Arabidopsis development by increasing the number of lateral roots and having a major effect on AP growth and metabolite profile. Our results indicate that GAPCp1 is not functionally important in photosynthetic cells but plays a fundamental role in roots and in heterotrophic cells of the AP. Specifically, GAPCp activity may be required in root meristems and the root cap for normal primary root growth. Transcriptomic and metabolomic analyses indicate that the lack of GAPCp activity affects nitrogen and carbon metabolism as well as mineral nutrition and that glycerate and glutamine are the main metabolites responding to GAPCp activity. Thus, GAPCp could be an important metabolic connector of glycolysis with other pathways, such as the phosphorylated pathway of serine biosynthesis, the ammonium assimilation pathway, or the metabolism of γ-aminobutyrate, which in turn affect plant development.

  4. Plastidial Glycolytic Glyceraldehyde-3-Phosphate Dehydrogenase Is an Important Determinant in the Carbon and Nitrogen Metabolism of Heterotrophic Cells in Arabidopsis1

    PubMed Central

    Anoman, Armand D.; Muñoz-Bertomeu, Jesús; Rosa-Téllez, Sara; Flores-Tornero, María; Serrano, Ramón; Bueso, Eduardo; Fernie, Alisdair R.; Segura, Juan; Ros, Roc

    2015-01-01

    This study functionally characterizes the Arabidopsis (Arabidopsis thaliana) plastidial glycolytic isoforms of glyceraldehyde-3-phosphate dehydrogenase (GAPCp) in photosynthetic and heterotrophic cells. We expressed the enzyme in gapcp double mutants (gapcp1gapcp2) under the control of photosynthetic (Rubisco small subunit RBCS2B [RBCS]) or heterotrophic (phosphate transporter PHT1.2 [PHT]) cell-specific promoters. Expression of GAPCp1 under the control of RBCS in gapcp1gapcp2 had no significant effect on the metabolite profile or growth in the aerial part (AP). GAPCp1 expression under the control of the PHT promoter clearly affected Arabidopsis development by increasing the number of lateral roots and having a major effect on AP growth and metabolite profile. Our results indicate that GAPCp1 is not functionally important in photosynthetic cells but plays a fundamental role in roots and in heterotrophic cells of the AP. Specifically, GAPCp activity may be required in root meristems and the root cap for normal primary root growth. Transcriptomic and metabolomic analyses indicate that the lack of GAPCp activity affects nitrogen and carbon metabolism as well as mineral nutrition and that glycerate and glutamine are the main metabolites responding to GAPCp activity. Thus, GAPCp could be an important metabolic connector of glycolysis with other pathways, such as the phosphorylated pathway of serine biosynthesis, the ammonium assimilation pathway, or the metabolism of γ-aminobutyrate, which in turn affect plant development. PMID:26134167

  5. Nitrogen

    USGS Publications Warehouse

    Apodaca, L.E.

    2010-01-01

    Ammonia was produced by 13 companies at 23 plants in 16 states during 2009. Sixty percent of all U.S. ammonia production capacity was centered in Louisiana. Oklahoma and Texas because of those states' large reserves of natural gas, the dominant domestic feedstock. In 2009, U.S. producers operated at about 83 percent of their rated capacity (excluding plants that were idle for the entire year). Five companies — Koch Nitrogen Co.; Terra Industries Inc.; CF Industries Inc.; PCS Nitrogen Inc. and Agrium Inc., in descending order — accounted for 80 percent of the total U.S. ammonia production capacity. U.S. production was estimated to be 7.7 Mt (8.5 million st) of nitrogen (N) content in 2009 compared with 7.85 Mt (8.65 million st) of N content in 2008. Apparent consumption was estimated to have decreased to 12.1 Mt (13.3 million st) of N, a 10-percent decrease from 2008. The United States was the world's fourth-ranked ammonia producer and consumer following China, India and Russia. Urea, ammonium nitrate, ammonium phosphates, nitric acid and ammonium sulfate were the major derivatives of ammonia in the United States, in descending order of importance.

  6. Metabolism of a nitrogen-enriched coastal marine lagoon during the summertime

    USGS Publications Warehouse

    Howarth, Robert W.; Hayn, Melanie; Marino, Roxanne M.; Ganju, Neil; Foreman, Kenneth H.; McGlathery, Karen; Giblin, Anne E.; Berg, Peter; Walker, Jeffrey D.

    2014-01-01

    We measured metabolism rates in a shallow, nitrogen-enriched coastal marine ecosystem on Cape Cod (MA, USA) during seven summers using an open-water diel oxygen method. We compared two basins, one directly receiving most of the nitrogen (N) load (“Snug Harbor”) and another further removed from the N load and better flushed (“Outer Harbor”). Both dissolved oxygen and pH varied greatly over the day, increasing in daylight and decreasing at night. The more N-enriched basin frequently went hypoxic during the night, and the pH in both basins was low (compared to standard seawater) when the oxygen levels were low, due to elevated carbon dioxide. Day-to-day variation in gross primary production (GPP) was high and linked in part to variation in light. Whole-ecosystem respiration tended to track this short-term variation in GPP, suggesting that respiration by the primary producers often dominated whole-system respiration. GPP was higher in the more N-loaded Snug Harbor. Seagrasses covered over 60 % of the area of the better-flushed, Outer Harbor throughout our study and were the major contributors to GPP there. Seagrasses covered 20 % of the area in Snug Harbor for the first 5 years of our study, and their contribution to GPP was relatively small. The seagrasses in Snug Harbor died off completely in the 6th year, but GPP remained high then and in the subsequent year. Overall, rates of phytoplankton GPP were relatively low, suggesting that benthic micro- and macro-algae may be the dominant primary producers in Snug Harbor in most years. Net ecosystem production in both Snug Harbor and the Outer Harbor was variable from year to year, showing net heterotrophy in some years and net autotrophy in others, with a trend towards increasing autotrophy over the 7 years reported here.

  7. Dissimilatory Metabolism of Nitrogen Oxides in Bacteria:Comparative Reconstruction of Transcriptional Networks

    SciTech Connect

    Rodionov, Dmitry A.; Dubchak, Inna L.; Arkin, Adam P.; Alm, EricJ.; Gelfand, Mikhail S.

    2005-09-01

    Bacterial response to nitric oxide (NO) is of major importance since NO is an obligatory intermediate of the nitrogen cycle. Transcriptional regulation of the dissimilatory nitric oxides metabolism in bacteria is diverse and involves FNR-like transcription factors HcpR, DNR and NnrR, two-component systems NarXL and NarQP, NO-responsive activator NorR, and nitrite sensitive repressor NsrR. Using comparative genomics approaches we predict DNA-binding signals for these transcriptional factors and describe corresponding regulons in available bacterial genomes. Within the FNR family of regulators, we observed a correlation of two specificity-determining amino acids and contacting bases in corresponding DNA signal. Highly conserved regulon HcpR for the hybrid cluster protein and some other redox enzymes is present in diverse anaerobic bacteria including Clostridia, Thermotogales and delta-proteobacteria. NnrR and DNR control denitrification in alpha- and beta-proteobacteria, respectively. Sigma-54-dependent NorR regulon found in some gamma- and beta-proteobacteria contains various enzymes involved in the NO detoxification. Repressor NsrR, which was previously known to control only nitrite reductase operon in Nitrosomonas spp., appears to be the master regulator of the nitric oxides metabolism not only in most gamma- and beta-proteobacteria (including well-studied species like Escherichia coli), but also in Gram-positive Bacillus and Streptomyces species. Positional analysis and comparison of regulatory regions of NO detoxification genes allows us to propose the candidate NsrR-binding signal. The most conserved member of the predicted NsrR regulon is the NO-detoxifying flavohemoglobin Hmp. In enterobacteria, the regulon includes also two nitrite-responsive loci, nipAB (hcp-hcr) and nipC(dnrN), thus confirming the identity of the effector, i.e., nitrite. The proposed NsrR regulons in Neisseria and some other species are extended to include denitrification genes. As the

  8. Zeolite Soil Application Method Affects Inorganic Nitrogen, Moisture, and Corn Growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adoption of new management techniques which improve soil water storage and soil nitrogen plant availability yet limit nitrogen leaching may help improve environmental quality. A benchtop study was conducted to determine the influence of a single urea fertilizer rate (224 kilograms of Nitrogen per ...

  9. Long-term monitoring reveals carbon–nitrogen metabolism key to microcystin production in eutrophic lakes

    PubMed Central

    Beversdorf, Lucas J.; Miller, Todd R.; McMahon, Katherine D.

    2015-01-01

    The environmental drivers contributing to cyanobacterial dominance in aquatic systems have been extensively studied. However, understanding of toxic vs. non-toxic cyanobacterial population dynamics and the mechanisms regulating cyanotoxin production remain elusive, both physiologically and ecologically. One reason is the disconnect between laboratory and field-based studies. Here, we combined 3 years of temporal data, including microcystin (MC) concentrations, 16 years of long-term ecological research, and 10 years of molecular data to investigate the potential factors leading to the selection of toxic Microcystis and MC production. Our analysis revealed that nitrogen (N) speciation and inorganic carbon (C) availability might be important drivers of Microcystis population dynamics and that an imbalance in cellular C: N ratios may trigger MC production. More specifically, precipitous declines in ammonium concentrations lead to a transitional period of N stress, even in the presence of high nitrate concentrations, that we call the “toxic phase.” Following the toxic phase, temperature and cyanobacterial abundance remained elevated but MC concentrations drastically declined. Increases in ammonium due to lake turnover may have led to down regulation of MC synthesis or a shift in the community from toxic to non-toxic species. While total phosphorus (P) to total N ratios were relatively low over the time-series, MC concentrations were highest when total N to total P ratios were also highest. Similarly, high C: N ratios were also strongly correlated to the toxic phase. We propose a metabolic model that corroborates molecular studies and reflects our ecological observations that C and N metabolism may regulate MC production physiologically and ecologically. In particular, we hypothesize that an imbalance between 2-oxoglutarate and ammonium in the cell regulates MC synthesis in the environment. PMID:26029192

  10. Comparison of environmental and isolate Sulfobacillus genomes reveals diverse carbon, sulfur, nitrogen, and hydrogen metabolisms

    DOE PAGES

    Justice, Nicholas B.; Norman, Anders; Brown, Christopher T.; ...

    2014-12-15

    Bacteria of the genus Sulfobacillus are found worldwide as members of microbial communities that accelerate sulfide mineral dissolution in acid mine drainage environments (AMD), acid-rock drainage environments (ARD), as well as in industrial bioleaching operations. Despite their frequent identification in these environments, their role in biogeochemical cycling is poorly understood. Here we report draft genomes of five species of the Sulfobacillus genus (AMDSBA1-5) reconstructed by cultivation-independent sequencing of biofilms sampled from the Richmond Mine (Iron Mountain, CA). Three of these species (AMDSBA2, AMDSBA3, and AMDSBA4) have no cultured representatives while AMDSBA1 is a strain of S. benefaciens, and AMDSBA5 amore » strain of S. thermosulfidooxidans. We analyzed the diversity of energy conservation and central carbon metabolisms for these genomes and previously published Sulfobacillus genomes. Pathways of sulfur oxidation vary considerably across the genus, including the number and type of subunits of putative heterodisulfide reductase complexes likely involved in sulfur oxidation. The number and type of nickel-iron hydrogenase proteins varied across the genus, as does the presence of different central carbon pathways. Only the AMDSBA3 genome encodes a dissimilatory nitrate reducatase and only the AMDSBA5 and S. thermosulfidooxidans genomes encode assimilatory nitrate reductases. Lastly, within the genus, AMDSBA4 is unusual in that its electron transport chain includes a cytochrome bc type complex, a unique cytochrome c oxidase, and two distinct succinate dehydrogenase complexes. Overall, the results significantly expand our understanding of carbon, sulfur, nitrogen, and hydrogen metabolism within the Sulfobacillus genus.« less

  11. Realistic diversity loss and variation in soil depth independently affect community-level plant nitrogen use.

    PubMed

    Selmants, Paul C; Zavaleta, Erika S; Wolf, Amelia A

    2014-01-01

    Numerous experiments have demonstrated that diverse plant communities use nitrogen (N) more completely and efficiently, with implications for how species conservation efforts might influence N cycling and retention in terrestrial ecosystems. However, most such experiments have randomly manipulated species richness and minimized environmental heterogeneity, two design aspects that may reduce applicability to real ecosystems. Here we present results from an experiment directly comparing how realistic and randomized plant species losses affect plant N use across a gradient of soil depth in a native-dominated serpentine grassland in California. We found that the strength of the species richness effect on plant N use did not increase with soil depth in either the realistic or randomized species loss scenarios, indicating that the increased vertical heterogeneity conferred by deeper soils did not lead to greater complementarity among species in this ecosystem. Realistic species losses significantly reduced plant N uptake and altered N-use efficiency, while randomized species losses had no effect on plant N use. Increasing soil depth positively affected plant N uptake in both loss order scenarios but had a weaker effect on plant N use than did realistic species losses. Our results illustrate that realistic species losses can have functional consequences that differ distinctly from randomized losses, and that species diversity effects can be independent of and outweigh those of environmental heterogeneity on ecosystem functioning. Our findings also support the value of conservation efforts aimed at maintaining biodiversity to help buffer ecosystems against increasing anthropogenic N loading.

  12. Metabolism of organic acids, nitrogen and amino acids in chlorotic leaves of 'Honeycrisp' apple (Malus domestica Borkh) with excessive accumulation of carbohydrates.

    PubMed

    Wang, Huicong; Ma, Fangfang; Cheng, Lailiang

    2010-07-01

    Metabolite profiles and activities of key enzymes in the metabolism of organic acids, nitrogen and amino acids were compared between chlorotic leaves and normal leaves of 'Honeycrisp' apple to understand how accumulation of non-structural carbohydrates affects the metabolism of organic acids, nitrogen and amino acids. Excessive accumulation of non-structural carbohydrates and much lower CO(2) assimilation were found in chlorotic leaves than in normal leaves, confirming feedback inhibition of photosynthesis in chlorotic leaves. Dark respiration and activities of several key enzymes in glycolysis and tricarboxylic acid (TCA) cycle, ATP-phosphofructokinase, pyruvate kinase, citrate synthase, aconitase and isocitrate dehydrogenase were significantly higher in chlorotic leaves than in normal leaves. However, concentrations of most organic acids including phosphoenolpyruvate (PEP), pyruvate, oxaloacetate, 2-oxoglutarate, malate and fumarate, and activities of key enzymes involved in the anapleurotic pathway including PEP carboxylase, NAD-malate dehydrogenase and NAD-malic enzyme were significantly lower in chlorotic leaves than in normal leaves. Concentrations of soluble proteins and most free amino acids were significantly lower in chlorotic leaves than in normal leaves. Activities of key enzymes in nitrogen assimilation and amino acid synthesis, including nitrate reductase, glutamine synthetase, ferredoxin and NADH-dependent glutamate synthase, and glutamate pyruvate transaminase were significantly lower in chlorotic leaves than in normal leaves. It was concluded that, in response to excessive accumulation of non-structural carbohydrates, glycolysis and TCA cycle were up-regulated to "consume" the excess carbon available, whereas the anapleurotic pathway, nitrogen assimilation and amino acid synthesis were down-regulated to reduce the overall rate of amino acid and protein synthesis.

  13. Nitrogen-induced metabolic changes and molecular determinants of carbon allocation in Dunaliella tertiolecta

    PubMed Central

    Tan, Kenneth Wei Min; Lin, Huixin; Shen, Hui; Lee, Yuan Kun

    2016-01-01

    Certain species of microalgae are natural accumulators of lipids, while others are more inclined to store starch. However, what governs the preference to store lipids or starch is not well understood. In this study, the microalga Dunaliella tertiolecta was used as a model to study the global gene expression profile regulating starch accumulation in microalgae. D. tertiolecta, when depleted of nitrogen, produced only 1% of dry cell weight (DCW) in neutral lipids, while starch was rapidly accumulated up to 46% DCW. The increased in starch content was accompanied by a coordinated overexpression of genes shunting carbon towards starch synthesis, a response not seen in the oleaginous microalgae Nannochloropsis oceanica, Chlamydomonas reinhardtii or Chlorella vulgaris. Genes in the central carbon metabolism pathways, particularly those of the tricarboxylic acid cycle, were also simultaneously upregulated, indicating a robust interchange of carbon skeletons for anabolic and catabolic processes. In contrast, fatty acid and triacylglycerol synthesis genes were downregulated or unchanged, suggesting that lipids are not a preferred form of storage in these cells. This study reveals the transcriptomic influence behind storage reserve allocation in D. tertiolecta and provides valuable insights into the possible manipulation of genes for engineering microorganisms to synthesize products of interest. PMID:27849022

  14. Effects of UV-B and heavy metals on nitrogen and phosphorus metabolism in three cyanobacteria.

    PubMed

    Yadav, Shivam; Prajapati, Rajesh; Atri, Neelam

    2016-01-01

    Cyanobacteria sp. (diazotrophic and planktonic) hold a major position in ecosystem, former one due to their intrinsic capability of N2-fixation and later because of mineralization of organic matter. Unfortunately, their exposure to variety of abiotic stresses is unavoidable. Comparative analysis of interactive effect of UV-B and heavy metals (Cd/Zn) on nitrogen and phosphorus metabolism of three cyanobacteria (Anabaena, Microcystis, Nostoc) revealed additive inhibition (χ(2) significant p < 0.05) of NH4(+) and PO4(3-) uptake whereas increase in nitrate uptake upon UV-B + heavy metal exposure. Glutamine synthetase and Alkaline phosphatase activity was reduced after all treatments whereas Nitrate reductase activity showed slight stimulation in UV-B and UV-B + heavy metals treatment. Combination of UV-B and metals seems more detrimental to the NH4(+), PO4(3-) uptake, GS and APA activity. A significant stimulation in NO3(-) uptake and NR activity following exposure to UV-B in all the three cyanobacteria suggests UV-B-induced structural change(s) in the enzyme/carriers. Metals seem to compete for the binding sites of the enzymes and carriers; as noticed for Anabaena and Microcystis showing change in Km while no change in the Km value of Nostoc suggests non-competitive nutrient uptake. Higher accumulation and more adverse effect on Na(+) and K(+) efflux proposes Cd as more toxic compared to Zn.

  15. CO2 enrichment modulates ammonium nutrition in tomato adjusting carbon and nitrogen metabolism to stomatal conductance.

    PubMed

    Vega-Mas, Izargi; Marino, Daniel; Sánchez-Zabala, Joseba; González-Murua, Carmen; Estavillo, Jose María; González-Moro, María Begoña

    2015-12-01

    Ammonium (NH4(+)) toxicity typically occurs in plants exposed to high environmental NH4(+) concentration. NH4(+) assimilating capacity may act as a biochemical mechanism avoiding its toxic accumulation but requires a fine tuning between nitrogen assimilating enzymes and carbon anaplerotic routes. In this work, we hypothesized that extra C supply, exposing tomato plants cv. Agora Hybrid F1 to elevated atmospheric CO2, could improve photosynthetic process and thus ameliorate NH4(+) assimilation and tolerance. Plants were grown under nitrate (NO3(-)) or NH4(+) as N source (5-15mM), under two atmospheric CO2 levels, 400 and 800ppm. Growth and gas exchange parameters, (15)N isotopic signature, C and N metabolites and enzymatic activities were determined. Plants under 7.5mM N equally grew independently of the N source, while higher ammonium supply resulted toxic for growth. However, specific stomatal closure occurred in 7.5mM NH4(+)-fed plants under elevated CO2 improving water use efficiency (WUE) but compromising plant N status. Elevated CO2 annulled the induction of TCA anaplerotic enzymes observed at non-toxic NH4(+) nutrition under ambient CO2. Finally, CO2 enrichment benefited tomato growth under both nutritions, and although it did not alleviate tomato NH4(+) tolerance it did differentially regulate plant metabolism in N-source and -dose dependent manner.

  16. Nitrogen-induced metabolic changes and molecular determinants of carbon allocation in Dunaliella tertiolecta.

    PubMed

    Tan, Kenneth Wei Min; Lin, Huixin; Shen, Hui; Lee, Yuan Kun

    2016-11-16

    Certain species of microalgae are natural accumulators of lipids, while others are more inclined to store starch. However, what governs the preference to store lipids or starch is not well understood. In this study, the microalga Dunaliella tertiolecta was used as a model to study the global gene expression profile regulating starch accumulation in microalgae. D. tertiolecta, when depleted of nitrogen, produced only 1% of dry cell weight (DCW) in neutral lipids, while starch was rapidly accumulated up to 46% DCW. The increased in starch content was accompanied by a coordinated overexpression of genes shunting carbon towards starch synthesis, a response not seen in the oleaginous microalgae Nannochloropsis oceanica, Chlamydomonas reinhardtii or Chlorella vulgaris. Genes in the central carbon metabolism pathways, particularly those of the tricarboxylic acid cycle, were also simultaneously upregulated, indicating a robust interchange of carbon skeletons for anabolic and catabolic processes. In contrast, fatty acid and triacylglycerol synthesis genes were downregulated or unchanged, suggesting that lipids are not a preferred form of storage in these cells. This study reveals the transcriptomic influence behind storage reserve allocation in D. tertiolecta and provides valuable insights into the possible manipulation of genes for engineering microorganisms to synthesize products of interest.

  17. Adjustment of growth and central metabolism to a mild but sustained nitrogen-limitation in Arabidopsis.

    PubMed

    Tschoep, Hendrik; Gibon, Yves; Carillo, Petronia; Armengaud, Patrick; Szecowka, Marek; Nunes-Nesi, Adriano; Fernie, Alisdair R; Koehl, Karin; Stitt, Mark

    2009-03-01

    We have established a simple soil-based experimental system that allows a small and sustained restriction of growth of Arabidopsis by low nitrogen (N). Plants were grown in a large volume of a peat-vermiculite mix that contained very low levels of inorganic N. As a control, inorganic N was added in solid form to the peat-vermiculite mix, or plants were grown in conventional nutrient-rich solids. The low N growth regime led to a sustained 20% decrease of the relative growth rate over a period of 2 weeks, resulting in a two- to threefold decrease in biomass in 35- to 40-day-old plants. Plants in the low N regime contained lower levels of nitrate, lower nitrate reductase activity, lower levels of malate, fumarate and other organic acids and slightly higher levels of starch, as expected from published studies of N-limited plants. However, their rosette protein content was unaltered, and total and many individual amino acid levels increased compared with N-replete plants. This metabolic phenotype reveals that Arabidopsis responds adaptively to low N by decreasing the rate of growth, while maintaining the overall protein content, and maintaining or even increasing the levels of many amino acids.

  18. Metabolic Engineering to Develop a Pathway for the Selective Cleavage of Carbon-Nitrogen Bonds

    SciTech Connect

    John J. Kilbane II

    2005-10-01

    The objective of the project is to develop a biochemical pathway for the selective cleavage of C-N bonds in molecules found in petroleum. Specifically a novel biochemical pathway will be developed for the selective cleavage of C-N bonds in carbazole. The cleavage of the first C-N bond in carbazole is accomplished by the enzyme carbazole dioxygenase, that catalyzes the conversion of carbazole to 2-aminobiphenyl-2,3-diol. The genes encoding carbazole dioxygenase were cloned from Sphingomonas sp. GTIN11 and from Pseudomonas resinovorans CA10. The selective cleavage of the second C-N bond has been challenging, and efforts to overcome that challenge have been the focus of recent research in this project. Enrichment culture experiments succeeded in isolating bacterial cultures that can metabolize 2-aminobiphenyl, but no enzyme capable of selectively cleaving the C-N bond in 2-aminobiphenyl has been identified. Aniline is very similar to the structure of 2-aminobiphenyl and aniline dioxygenase catalyzes the conversion of aniline to catechol and ammonia. For the remainder of the project the emphasis of research will be to simultaneously express the genes for carbazole dioxygenase and for aniline dioxygenase in the same bacterial host and then to select for derivative cultures capable of using carbazole as the sole source of nitrogen.

  19. Molecular insight into the dynamic central metabolic pathways of Achromobacter xylosoxidans CF-S36 during heterotrophic nitrogen removal processes.

    PubMed

    Padhi, Soumesh Kumar; Maiti, Nikhil Kumar

    2017-01-01

    Organic carbon sources play a significant role in heterotrophic nitrogen consumption. This quintessential exploration is focused on carbon and nitrogen biogeochemical cycles in heterotrophic bacteria, capable of simultaneous nitrification and denitrification (SND). A heterotrophic bacterial strain Achromobacter xylosoxidans CF-S36 isolated from domestic wastewater efficiently eliminated ammonia, nitrate and nitrite by utilizing different carbon sources. The type of carbon utilized by strain CF-S36 determined the rate of heterotrophic nitrogen removal. Quantitative real-time PCR (qRT-PCR) analysis of genes of central carbon and nitrogen metabolism, signal transduction, electron transport chain (ETC) pathways and assays of enzymes of denitrification processes revealed the existence of well-coordinated link between carbon utilization and nitrogen elimination in bacterial cell. The most preferred carbon source for nitrification was succinate followed by glucose and acetate. Inhibitory effect of nitrite on glycolytic pathway and nitrogen assimilation genes attributes glucose as unfavorable carbon source for denitrification process in strain CF-S36. Acetate served as efficient carbon source for utilizing nitrite through denitrification process. The study demonstrated here might be useful to biogeochemical engineer to understand the involvement of heterotrophic bacteria in global biogeochemical cycle and to gain further insight into the diversified application of these microorganisms.

  20. Quantitative proteomics reveals the importance of nitrogen source to control glucosinolate metabolism in Arabidopsis thaliana and Brassica oleracea

    PubMed Central

    Marino, Daniel; Ariz, Idoia; Lasa, Berta; Santamaría, Enrique; Fernández-Irigoyen, Joaquín; González-Murua, Carmen; Aparicio Tejo, Pedro M.

    2016-01-01

    Accessing different nitrogen (N) sources involves a profound adaptation of plant metabolism. In this study, a quantitative proteomic approach was used to further understand how the model plant Arabidopsis thaliana adjusts to different N sources when grown exclusively under nitrate or ammonium nutrition. Proteome data evidenced that glucosinolate metabolism was differentially regulated by the N source and that both TGG1 and TGG2 myrosinases were more abundant under ammonium nutrition, which is generally considered to be a stressful situation. Moreover, Arabidopsis plants displayed glucosinolate accumulation and induced myrosinase activity under ammonium nutrition. Interestingly, these results were also confirmed in the economically important crop broccoli (Brassica oleracea var. italica). Moreover, these metabolic changes were correlated in Arabidopsis with the differential expression of genes from the aliphatic glucosinolate metabolic pathway. This study underlines the importance of nitrogen nutrition and the potential of using ammonium as the N source in order to stimulate glucosinolate metabolism, which may have important applications not only in terms of reducing pesticide use, but also for increasing plants’ nutritional value. PMID:27085186

  1. Metabolic syndrome - the consequence of lifelong treatment of bipolar affective disorder.

    PubMed

    Dadić-Hero, Elizabeta; Ruzić, Klementina; Grahovac, Tanja; Petranović, Duska; Graovac, Mirjana; Palijan, Tija Zarković

    2010-06-01

    Mood disturbances are characteristic and dominant feature of Mood disorders. Bipolar Affective Disorder (BAD) is a mood disorder which occurs equally in both sexes. BAD may occur in co morbidity with other mental diseases and disorders such as: Anorexia Nervosa, Bulimia Nervosa, Attention Deficit, Panic Disorder and Social Phobia. However, medical disorders (one or more) can also coexist with BAD. Metabolic syndrome is a combination of metabolic disorders that increase the risk of developing cardiovascular disease. A 61-year old female patient has been receiving continuous and systematic psychiatric treatment for Bipolar Affective Disorder for the last 39 years. The first episode was a depressive one and it occurred after a child delivery. Seventeen years ago the patient developed diabetes (diabetes type II), and twelve years ago arterial hypertension was diagnosed. High cholesterol and triglyceride levels as well as weight gain were objective findings. During the last nine years she has been treated for lower leg ulcer. Since metabolic syndrome includes abdominal obesity, hypertension, diabetes mellitus, increased cholesterol and serum triglyceride levels, the aforesaid patient can be diagnosed with Metabolic Syndrome. When treating Bipolar Affective Disorder, the antipsychotic drug choice should be careful and aware of its side-effects in order to avoid the development or aggravation of metabolic syndrome.

  2. Overexpressing of OsAMT1-3, a High Affinity Ammonium Transporter Gene, Modifies Rice Growth and Carbon-Nitrogen Metabolic Status

    PubMed Central

    Bao, Aili; Liang, Zhijun; Zhao, Zhuqing; Cai, Hongmei

    2015-01-01

    AMT1-3 encodes the high affinity NH4+ transporter in rice roots and is predominantly expressed under nitrogen starvation. In order to evaluate the effect of AMT1-3 gene on rice growth, nitrogen absorption and metabolism, we generated AMT1-3-overexpressing plants and analyzed the growth phenotype, yield, carbon and nitrogen metabolic status, and gene expression profiles. Although AMT1-3 mRNA accumulated in transgenic plants, these plants displayed significant decreases in growth when compared to the wild-type plants. The nitrogen uptake assay using a 15N tracer revealed poor nitrogen uptake ability in AMT1-3-overexpressing plants. We found significant decreases in AMT1-3-overexpressing plant leaf carbon and nitrogen content accompanied with a higher leaf C/N ratio. Significant changes in soluble proteins and carbohydrates were also observed in AMT1-3-overexpressing plants. In addition, metabolite profile analysis demonstrated significant changes in individual sugars, organic acids and free amino acids. Gene expression analysis revealed distinct expression patterns of genes that participate in carbon and nitrogen metabolism. Additionally, the correlation between the metabolites and gene expression patterns was consistent in AMT1-3-overexpressing plants under both low and high nitrogen growth conditions. Therefore, we hypothesized that the carbon and nitrogen metabolic imbalance caused by AMT1-3 overexpressing attributed to the poor growth and yield of transgenic plants. PMID:25915023

  3. Overexpressing of OsAMT1-3, a High Affinity Ammonium Transporter Gene, Modifies Rice Growth and Carbon-Nitrogen Metabolic Status.

    PubMed

    Bao, Aili; Liang, Zhijun; Zhao, Zhuqing; Cai, Hongmei

    2015-04-23

    AMT1-3 encodes the high affinity NH₄⁺ transporter in rice roots and is predominantly expressed under nitrogen starvation. In order to evaluate the effect of AMT1-3 gene on rice growth, nitrogen absorption and metabolism, we generated AMT1-3-overexpressing plants and analyzed the growth phenotype, yield, carbon and nitrogen metabolic status, and gene expression profiles. Although AMT1-3 mRNA accumulated in transgenic plants, these plants displayed significant decreases in growth when compared to the wild-type plants. The nitrogen uptake assay using a 15N tracer revealed poor nitrogen uptake ability in AMT1-3-overexpressing plants. We found significant decreases in AMT1-3-overexpressing plant leaf carbon and nitrogen content accompanied with a higher leaf C/N ratio. Significant changes in soluble proteins and carbohydrates were also observed in AMT1-3-overexpressing plants. In addition, metabolite profile analysis demonstrated significant changes in individual sugars, organic acids and free amino acids. Gene expression analysis revealed distinct expression patterns of genes that participate in carbon and nitrogen metabolism. Additionally, the correlation between the metabolites and gene expression patterns was consistent in AMT1-3-overexpressing plants under both low and high nitrogen growth conditions. Therefore, we hypothesized that the carbon and nitrogen metabolic imbalance caused by AMT1-3 overexpressing attributed to the poor growth and yield of transgenic plants.

  4. Growth, nitrogen uptake and flow in maize plants affected by root growth restriction.

    PubMed

    Xu, Liangzheng; Niu, Junfang; Li, Chunjian; Zhang, Fusuo

    2009-07-01

    The objective of the present study was to investigate the influence of a reduced maize root-system size on root growth and nitrogen (N) uptake and flow within plants. Restriction of shoot-borne root growth caused a strong decrease in the absorption of root: shoot dry weight ratio and a reduction in shoot growth. On the other hand, compensatory growth and an increased N uptake rate in the remaining roots were observed. Despite the limited long-distance transport pathway in the mesocotyl with restriction of shoot-borne root growth, N cycling within these plants was higher than those in control plants, implying that xylem and phloem flow velocities via the mesocotyl were considerably higher than in plants with an intact root system. The removal of the seminal roots in addition to restricting shoot-borne root development did not affect whole plant growth and N uptake, except for the stronger compensatory growth of the primary roots. Our results suggest that an adequate N supply to maize plant is maintained by compensatory growth of the remaining roots, increased N uptake rate and flow velocities within the xylem and phloem via the mesocotyl, and reduction in the shoot growth rate.

  5. Fungal endophyte Phomopsis liquidambari affects nitrogen transformation processes and related microorganisms in the rice rhizosphere

    PubMed Central

    Yang, Bo; Wang, Xiao-Mi; Ma, Hai-Yan; Yang, Teng; Jia, Yong; Zhou, Jun; Dai, Chuan-Chao

    2015-01-01

    The endophytic fungus Phomopsis liquidambari performs an important ecosystem service by assisting its host with acquiring soil nitrogen (N), but little is known regarding how this fungus influences soil N nutrient properties and microbial communities. In this study, we investigated the impact of P. liquidambari on N dynamics, the abundance and composition of N cycling genes in rhizosphere soil treated with three levels of N (urea). Ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB) and diazotrophs were assayed using quantitative real-time polymerase chain reaction and denaturing gradient gel electrophoresis at four rice growing stages (S0: before planting, S1: tillering stage, S2: grain filling stage, and S3: ripening stage). A significant increase in the available nitrate and ammonium contents was found in the rhizosphere soil of endophyte-infected rice under low N conditions. Moreover, P. liquidambari significantly increased the potential nitrification rates, affected the abundance and community structure of AOA, AOB, and diazotrophs under low N conditions in the S1 and S2 stages. The root exudates were determined due to their important role in rhizosphere interactions. P. liquidambari colonization altered the exudation of organic compounds by rice roots and P. liquidambari increased the concentration of soluble saccharides, total free amino acids and organic acids in root exudates. Plant-soil feedback mechanisms may be mediated by the rice-endophyte interaction, especially in nutrient-limited soil. PMID:26441912

  6. Nitrogen multitemporal monitoring through mosses in urban areas affected by mud volcanoes around Mt. Etna, Italy.

    PubMed

    Bonanno, Giuseppe

    2013-10-01

    Nitrogen emissions were assessed by using mosses as bioindicators in a densely inhabited area affected by mud volcanoes. Such volcanoes, locally called Salinelle, are phenomena that occur around Mt. Etna (Sicily, Italy), and are interpreted as the surface outflow of a hydrothermal system located below Mt. Etna, which releases sedimentary fluids (hydrocarbons and Na-Cl brines) along with magmatic gases (mainly CO2 and He). To date, N emissions from such mud volcanoes have been only quantitatively assessed, and no biomonitoring campaigns are reported about the cumulative effects of these emissions. This study analyzed N concentrations in moss, water and soil samples, collected in a 4-year monitoring campaign. The bryophyte Bryum argenteum, a species widely adopted in surveys of atmospheric pollution, was used as a biological indicator. N concentrations in biomonitors showed relatively low values in the study sites. However, the results of this study suggest that N emissions from Salinelle may have an impact on surrounding ecosystems because N values in moss and water showed a significant correlation. N oxides, in particular, contribute to acidification of ecosystems, thus multitemporal biomonitoring is recommended, especially in those areas where N emitting sources are anthropogenic and natural.

  7. Grazing intensity significantly affects belowground carbon and nitrogen cycling in grassland ecosystems: a meta-analysis.

    PubMed

    Zhou, Guiyao; Zhou, Xuhui; He, Yanghui; Shao, Junjiong; Hu, Zhenhong; Liu, Ruiqiang; Zhou, Huimin; Hosseinibai, Shahla

    2017-03-01

    Livestock grazing activities potentially alter ecosystem carbon (C) and nitrogen (N) cycles in grassland ecosystems. Despite the fact that numerous individual studies and a few meta-analyses had been conducted, how grazing, especially its intensity, affects belowground C and N cycling in grasslands remains unclear. In this study, we performed a comprehensive meta-analysis of 115 published studies to examine the responses of 19 variables associated with belowground C and N cycling to livestock grazing in global grasslands. Our results showed that, on average, grazing significantly decreased belowground C and N pools in grassland ecosystems, with the largest decreases in microbial biomass C and N (21.62% and 24.40%, respectively). In contrast, belowground fluxes, including soil respiration, soil net N mineralization and soil N nitrification increased by 4.25%, 34.67% and 25.87%, respectively, in grazed grasslands compared to ungrazed ones. More importantly, grazing intensity significantly affected the magnitude (even direction) of changes in the majority of the assessed belowground C and N pools and fluxes, and C : N ratio as well as soil moisture. Specifically,light grazing contributed to soil C and N sequestration whereas moderate and heavy grazing significantly increased C and N losses. In addition, soil depth, livestock type and climatic conditions influenced the responses of selected variables to livestock grazing to some degree. Our findings highlight the importance of the effects of grazing intensity on belowground C and N cycling, which may need to be incorporated into regional and global models for predicting effects of human disturbance on global grasslands and assessing the climate-biosphere feedbacks.

  8. Spatial gradient in nitrogen deposition affects plant species frequency in acidic grasslands.

    PubMed

    Pannek, A; Duprè, C; Gowing, D J G; Stevens, C J; Diekmann, M

    2015-01-01

    Anthropogenic eutrophication impacts ecosystems worldwide. Here, we use a vegetation dataset from semi-natural grasslands on acidic soils sampled along a gradient in north-western Europe to examine the response of species frequency to nitrogen (N) deposition, controlling for the effects of other environmental variables. A second dataset of acidic grasslands from Germany and the Netherlands containing plots from different time periods was analysed to examine whether the results of the spatial gradient approach coincided with temporal changes in the abundance of species. Out of 44 studied species, 16 were affected by N deposition, 12 of them negatively. Soil pH and phosphorus (P) influenced 24 and 14 species, respectively, predominantly positively. Fewer species were related to the soil contents of NO3(-) or NH4(+), with no significant differences between the number of positive and negative effects. Whereas the temporal change of species was unrelated to their responses to pH, species responding negatively to N deposition, soil P and NO3(-) showed a significant decline over time in both countries. Species that were negatively affected by high N deposition and/or high soil P also showed a negative temporal trend and could be characterised by short stature and slow growth. The results confirm the negative role of N deposition for many plant species in semi-natural acidic grasslands. The negative temporal trends of species sensitive to high N deposition and soil P values clearly show a need for maintaining low soil nutrient status and for restoring the formerly infertile conditions in nutrient-enriched grasslands.

  9. Do Forest Age and Soil Depth Affect Carbon and Nitrogen Adsorption in Mineral Horizons?

    NASA Astrophysics Data System (ADS)

    Spina, P. G.; Lovett, G. M.; Fuss, C. B.; Goodale, C. L.; Lang, A.; Fahey, T.

    2015-12-01

    Mineral soils retain large amounts of organic matter through sorption on the surfaces of mineral soils, the largest pools of carbon (C) and nitrogen (N) in the forests of the northeastern U.S. In addition to determining organic matter storage, adsorption and desorption processes are important controllers of runoff chemistry. We are studying adsorption dynamics of mineral soils collected from a chronosequence of hardwood forest sites in the White Mountains, NH to determine how soils vary in their DOM adsorption capacities as a function of effective C and N saturation. We hypothesize that forest age determines proximity to saturation because young forests may need to mine soil organic matter (SOM) in mineral soils to obtain nitrogen to meet growth demands, while the soils of older forests have had time to reaccumulate SOM, eventually reaching C and N saturation. Consequently, we expect adsorption capacities to first increase with forest age in young forests, as the trees mine C and N from mineral surfaces. They will then decrease with forest age in older forests as mining slows and C and N begin to re-accumulate. Batch experiments were conducted with mineral soil samples and dilutions of forest floor leachate. However, preliminary results from a mature forest site (about 100 years old), which we predicted to be a low point of C and N saturation from decades of mining, contradict expectations. Dissolved organic carbon (DOC) adsorption in its shallow mineral soil layers (0-3 cm below E or A horizons) are lower than younger sites ranging from 20 to about 40 years old. In addition to forest age, soil depths also affect N retention dynamics in forest soils. We hypothesized that deeper mineral soils might have greater adsorption capacities due to the fact that they are exposed to less DOC and DON leaching from organic layers and therefore less saturated. Results from the same mature forest site confirm this. Soils from 3-10 cm depth have more potential to adsorb DOC and

  10. The cockroach Blattella germanica obtains nitrogen from uric acid through a metabolic pathway shared with its bacterial endosymbiont.

    PubMed

    Patiño-Navarrete, Rafael; Piulachs, Maria-Dolors; Belles, Xavier; Moya, Andrés; Latorre, Amparo; Peretó, Juli

    2014-07-01

    Uric acid stored in the fat body of cockroaches is a nitrogen reservoir mobilized in times of scarcity. The discovery of urease in Blattabacterium cuenoti, the primary endosymbiont of cockroaches, suggests that the endosymbiont may participate in cockroach nitrogen economy. However, bacterial urease may only be one piece in the entire nitrogen recycling process from insect uric acid. Thus, in addition to the uricolytic pathway to urea, there must be glutamine synthetase assimilating the released ammonia by the urease reaction to enable the stored nitrogen to be metabolically usable. None of the Blattabacterium genomes sequenced to date possess genes encoding for those enzymes. To test the host's contribution to the process, we have sequenced and analysed Blattella germanica transcriptomes from the fat body. We identified transcripts corresponding to all genes necessary for the synthesis of uric acid and its catabolism to urea, as well as for the synthesis of glutamine, asparagine, proline and glycine, i.e. the amino acids required by the endosymbiont. We also explored the changes in gene expression with different dietary protein levels. It appears that the ability to use uric acid as a nitrogen reservoir emerged in cockroaches after its age-old symbiotic association with bacteria.

  11. Nitrogen metabolism in Sinorhizobium meliloti-alfalfa symbiosis: dissecting the role of GlnD and PII proteins.

    PubMed

    Yurgel, Svetlana N; Rice, Jennifer; Kahn, Michael L

    2012-03-01

    To contribute nitrogen for plant growth and establish an effective symbiosis with alfalfa, Sinorhizobium meliloti Rm1021 needs normal operation of the GlnD protein, a bifunctional uridylyltransferase/uridylyl-cleavage enzyme that measures cellular nitrogen status and initiates a nitrogen stress response (NSR). However, the only two known targets of GlnD modification in Rm1021, the PII proteins GlnB and GlnK, are not necessary for effectiveness. We introduced a Tyr→Phe variant of GlnB, which cannot be uridylylated, into a glnBglnK background to approximate the expected state in a glnD-sm2 mutant, and this strain was effective. These results suggested that unmodified PII does not inhibit effectiveness. We also generated a glnBglnK-glnD triple mutant and used this and other mutants to dissect the role of these proteins in regulating the free-living NSR and nitrogen metabolism in symbiosis. The glnD-sm2 mutation was dominant to the glnBglnK mutations in symbiosis but recessive in some free-living phenotypes. The data show that the GlnD protein has a role in free-living growth and in symbiotic nitrogen exchange that does not depend on the PII proteins, suggesting that S. meliloti GlnD can communicate with the cell by alternate mechanisms.

  12. Absence of cumulus cells during in vitro maturation affects lipid metabolism in bovine oocytes.

    PubMed

    Auclair, Sylvain; Uzbekov, Rustem; Elis, Sébastien; Sanchez, Laura; Kireev, Igor; Lardic, Lionel; Dalbies-Tran, Rozenn; Uzbekova, Svetlana

    2013-03-15

    Cumulus cells (CC) surround the oocyte and are coupled metabolically through regulation of nutrient intake. CC removal before in vitro maturation (IVM) decreases bovine oocyte developmental competence without affecting nuclear meiotic maturation. The objective was to investigate the influence of CC on oocyte cytoplasmic maturation in relation to energy metabolism. IVM with either cumulus-enclosed (CEO) or -denuded (DO) oocytes was performed in serum-free metabolically optimized medium. Transmission electron microscopy revealed different distribution of membrane-bound vesicles and lipid droplets between metaphase II DO and CEO. By Nile Red staining, a significant reduction in total lipid level was evidenced in DO. Global transcriptomic analysis revealed differential expression of genes regulating energy metabolism, transcription, and translation between CEO and DO. By Western blot, fatty acid synthase (FAS) and hormone-sensitive phospholipase (HSL) proteins were detected in oocytes and in CC, indicating a local lipogenesis and lypolysis. FAS protein was significantly less abundant in DO that in CEO and more highly expressed in CC than in the oocytes. On the contrary, HSL protein was more abundant in oocytes than in CC. In addition, active Ser⁵⁶³-phosphorylated HSL was detected in the oocytes only after IVM, and its level was similar in CEO and DO. In conclusion, absence of CC during IVM affected lipid metabolism in the oocyte and led to suboptimal cytoplasmic maturation. Thus, CC may influence the oocyte by orienting the consumption of nutritive storage via regulation of local fatty acid synthesis and lipolysis to provide energy for maturation.

  13. Effect of a compost and its water-soluble fractions on key enzymes of nitrogen metabolism in maize seedlings.

    PubMed

    Vaccaro, Silvia; Muscolo, Adele; Pizzeghello, Diego; Spaccini, Riccado; Piccolo, Alessandro; Nardi, Serenella

    2009-12-09

    The growing concern on long-term productivity of agroecosystems has emphasized the need to develop management strategies to maintain and protect soil resources, particularly soil organic matter (SOM). Among these, the composting process allows both recycling of the increasing amount of organic waste materials and restoration of the content of organic matter in soil. A sequential chemical fractionation into structurally unbound (SU), weakly bound (WB) and strongly bound (SB) compounds was applied to a bulk compost, and its soluble fractions were extracted in water, either after oxidation of compost suspension with an oxygen flux (TEA), or without oxidation but separated into hydrophilic (HiDOM) and hydrophobic (HoDOM) components. The ratio of hydrophilic over hydrophobic compounds decreased in the order HiDOM > TEA > compost > HoDOM, while TEA and compost showed the largest content of SU and WB components, respectively. Such chemically characterized bulk compost and fractions were tested on maize seedlings grown in sand and in hydroponic conditions, and the effects on plant growth and nitrogen metabolism were measured. The structurally complex bulk compost and the hydrophobic HoDOM fraction negatively affected plant growth, whereas the hydrophilic and less-structured fractions (HiDOM and TEA) showed large positive effects on both growth and enzymatic activities of plants. These results suggest that composted organic matter can become useful to stimulate plant growth if the content of potentially bioavailable hydrophilic and poorly structured components is large. These components may be progressively separated from the compost matrix and contribute to the dynamics of natural organic matter in soil.

  14. Stretching Your Energetic Budget: How Tendon Compliance Affects the Metabolic Cost of Running

    PubMed Central

    Uchida, Thomas K.; Hicks, Jennifer L.; Dembia, Christopher L.; Delp, Scott L.

    2016-01-01

    Muscles attach to bones via tendons that stretch and recoil, affecting muscle force generation and metabolic energy consumption. In this study, we investigated the effect of tendon compliance on the metabolic cost of running using a full-body musculoskeletal model with a detailed model of muscle energetics. We performed muscle-driven simulations of running at 2–5 m/s with tendon force–strain curves that produced between 1 and 10% strain when the muscles were developing maximum isometric force. We computed the average metabolic power consumed by each muscle when running at each speed and with each tendon compliance. Average whole-body metabolic power consumption increased as running speed increased, regardless of tendon compliance, and was lowest at each speed when tendon strain reached 2–3% as muscles were developing maximum isometric force. When running at 2 m/s, the soleus muscle consumed less metabolic power at high tendon compliance because the strain of the tendon allowed the muscle fibers to operate nearly isometrically during stance. In contrast, the medial and lateral gastrocnemii consumed less metabolic power at low tendon compliance because less compliant tendons allowed the muscle fibers to operate closer to their optimal lengths during stance. The software and simulations used in this study are freely available at simtk.org and enable examination of muscle energetics with unprecedented detail. PMID:26930416

  15. Lysine biosynthesis and nitrogen metabolism in quinoa (Chenopodium quinoa): study of enzymes and nitrogen-containing compounds.

    PubMed

    Varisi, Vanderlei A; Camargos, Liliane S; Aguiar, Leandro F; Christofoleti, Renata M; Medici, Leonardo O; Azevedo, Ricardo A

    2008-01-01

    Aspartate kinase (AK, EC 2.7.2.4), homoserine dehydrogenase (HSDH, EC 1.1.1.3) and dihydrodipicolinate synthase (DHDPS, EC 4.2.1.52) were isolated and partially purified from immature Chenopodium quinoa Willd seeds. Enzyme activities were studied in the presence of the aspartate-derived amino acids lysine, threonine and methionine and also the lysine analogue S-2-aminoethyl-l-cysteine (AEC), at 1 mM and 5 mM. The results confirmed the existence of, at least, two AK isoenzymes, one inhibited by lysine and the other inhibited by threonine, the latter being predominant in quinoa seeds. HSDH activity was also shown to be partially inhibited by threonine, whereas some of the activity was resistant to the inhibitory effect, indicating the presence of two isoenzymes, one resistant and another sensitive to threonine inhibition. Only one DHDPS isoenzyme highly sensitive to lysine inhibition was detected. The results suggest that the high concentration of lysine observed in quinoa seeds is possibly due to a combined effect of increased lysine synthesis and accumulation in the soluble form and/or as protein lysine. Nitrogen assimilation was also investigated and based on nitrate content, nitrate reductase activity, amino acid distribution and ureide content, the leaves were identified as the predominant site of nitrate reduction in this plant species. The amino acid profile analysis in leaves and roots also indicated an important role of soluble glutamine as a nitrogen transporting compound.

  16. Xylitol affects the intestinal microbiota and metabolism of daidzein in adult male mice.

    PubMed

    Tamura, Motoi; Hoshi, Chigusa; Hori, Sachiko

    2013-12-10

    This study examined the effects of xylitol on mouse intestinal microbiota and urinary isoflavonoids. Xylitol is classified as a sugar alcohol and used as a food additive. The intestinal microbiota seems to play an important role in isoflavone metabolism. Xylitol feeding appears to affect the gut microbiota. We hypothesized that dietary xylitol changes intestinal microbiota and, therefore, the metabolism of isoflavonoids in mice. Male mice were randomly divided into two groups: those fed a 0.05% daidzein with 5% xylitol diet (XD group) and those fed a 0.05% daidzein-containing control diet (CD group) for 28 days. Plasma total cholesterol concentrations were significantly lower in the XD group than in the CD group (p < 0.05). Urinary amounts of equol were significantly higher in the XD group than in the CD group (p < 0.05). The fecal lipid contents (% dry weight) were significantly greater in the XD group than in the CD group (p < 0.01). The cecal microbiota differed between the two dietary groups. The occupation ratios of Bacteroides were significantly greater in the CD than in the XD group (p < 0.05). This study suggests that xylitol has the potential to affect the metabolism of daidzein by altering the metabolic activity of the intestinal microbiota and/or gut environment. Given that equol affects bone health, dietary xylitol plus isoflavonoids may exert a favorable effect on bone health.

  17. Relationship between efficiency of nitrogen utilization and isotopic nitrogen fractionation in dairy cows: contribution of digestion v. metabolism?

    PubMed

    Cantalapiedra-Hijar, G; Fouillet, H; Huneau, J F; Fanchone, A; Doreau, M; Nozière, P; Ortigues-Marty, I

    2016-02-01

    Animal tissues are naturally 15N enriched relative to their diet and the extent of this difference (Δ15Nanimal-diet) has been correlated to the efficiency of N assimilation in different species. The rationale is that transamination and deamination enzymes, involved in amino acid metabolism are likely to preferentially convert amino groups containing 14N over 15N. However, in ruminants the contribution of rumen bacterial metabolism relative to animal tissues metabolism to naturally enrich animal proteins in terms of 15N has been not assessed yet. The objective of this study was to assess the impact of rumen and digestion processes on the relationship between Δ15Nanimal-diet and efficiency of N utilization for milk protein yield (milk N efficiency (MNE); milk N yield/N intake) as well as the relationship between the 15N natural abundance of rumen bacteria and the efficiency of N use at the rumen level. Solid- and liquid-associated rumen bacteria, duodenal digesta, feces and plasma proteins were obtained (n=16) from four lactating Holstein cows fed four different diets formulated at two metabolizable protein supplies (80% v. 110% of protein requirements) crossed by two different dietary energy source (diets rich in starch v. fiber). We measured the isotopic N fractionation between animal and diet (Δ15Nanimal-diet) in these different body pools. The Δ15Nanimal-diet was negatively correlated with MNE when measured in solid-associated rumen bacteria, duodenal digesta, feces and plasma proteins, with the strongest correlation found for the latter. However, our results showed a very weak 15N enrichment of duodenal digesta (Δ15Nduodenal digesta-diet mean value=0.42) compared with that observed in plasma proteins (Δ15Nplasma protein-diet mean value=2.41). These data support the idea that most of the isotopic N fractionation observed in ruminant proteins (Δ15Nplasma protein-diet) has a metabolic origin with very little direct impact of the overall digestion process on

  18. Xylella fastidiosa disturbs nitrogen metabolism and causes a stress response in sweet orange Citrus sinensis cv. Pera.

    PubMed

    Purcino, Rúbia P; Medina, Camilo Lázaro; Martins de Souza, Daniel; Winck, Flávia Vischi; Machado, Eduardo Caruso; Novello, José Camilo; Machado, Marcos Antonio; Mazzafera, Paulo

    2007-01-01

    Xylella fastidiosa (Xf) is a fastidious bacterium that grows exclusively in the xylem of several important crop species, including grape and sweet orange (Citrus sinensis L. Osb.) causing Pierce disease and citrus variegated chlorosis (CVC), respectively. The aim of this work was to study the nitrogen metabolism of a highly susceptible variety of sweet orange cv. 'Pêra' (C. sinensis L. Osbeck) infected with Xf. Plants were artificially infected and maintained in the greenhouse until they have developed clear disease symptoms. The content of nitrogen compounds and enzymes of the nitrogen metabolism and proteases in the xylem sap and leaves of diseased (DP) and uninfected healthy (HP) plants was studied. The activity of nitrate reductase in leaves did not change in DP, however, the activity of glutamine synthetase was significantly higher in these leaves. Although amino acid concentration was slightly higher in the xylem sap of DP, the level dropped drastically in the leaves. The protein contents were lower in the sap and in leaves of DP. DP and HP showed the same amino acid profiles, but different proportions were observed among them, mainly for asparagine, glutamine, and arginine. The polyamine putrescine was found in high concentrations only in DP. Protease activity was higher in leaves of DP while, in the xylem sap, activity was detected only in DP. Bidimensional electrophoresis showed a marked change in the protein pattern in DP. Five differentially expressed proteins were identified (2 from HP and 3 from DP), but none showed similarity with the genomic (translated) and proteomic database of Xf, but do show similarity with the proteins thaumatin, mucin, peroxidase, ABC-transporter, and strictosidine synthase. These results showed that significant changes take place in the nitrogen metabolism of DP, probably as a response to the alterations in the absorption, assimilation and distribution of N in the plant.

  19. Metabolic plasticity of nitrogen assimilation by Porphyra umbilicalis (Linnaeus) Kützing

    NASA Astrophysics Data System (ADS)

    Kim, Jang K.; Kraemer, George P.; Yarish, Charles

    2012-12-01

    The physical stresses associated with emersion have long been considered major factors determining the vertical zonation of intertidal seaweeds. We examined Porphyra umbilicalis (Linnaeus) Kützing thalli from the vertical extremes in elevation of an intertidal population ( i.e. upper and lower intertidal zones) to determine whether Porphyra thalli acclimate to different vertical elevations on the shore with different patterns of nitrate uptake and nitrate reductase (NR) and glutamine synthetase (GS) activities in response to different degrees of emersion stress. We found that the nitrate uptake and NR recovery in the emersed tissues took longer in lower intertidal sub-population than in upper intertidal sub-population; and GS activity was also significantly affected by emersion and, interestingly, such an activity was enhanced by emersion of thalli from both upper and lower intertidal zones. These results suggested that intra-population variability in post-emersion recovery of physiological functions such as nutrient uptake and NR activity enables local adaptation and contributes to the wide vertical distribution of P. umbilicalis. The high GS activity during periodic emersion stress may be a protective mechanism enabling P. umbilicalis to assimilate nitrogen quickly when it again becomes available, and may also be an evidence of photorespiration during emersion.

  20. Role of soil erodibility in affecting available nitrogen and phosphorus losses under simulated rainfall

    NASA Astrophysics Data System (ADS)

    Wang, Guoqiang; Wu, Binbin; Zhang, Lei; Jiang, Hong; Xu, Zongxue

    2014-06-01

    The loss of available nutrients and the effects of soil erodibility on available nutrients losses were rarely researched. Here, laboratory simulation experiments were conducted to determine the soil erodibility effects on the available nitrogen (AN) and phosphorus (AP) losses. The impacts of rainfall intensity and slope on AN and AP losses were also studied. Two contrasting agricultural soils (Burozems and Cinnamon) that occur throughout the northern erosion region of China were selected. Two rainfall intensities (60 and 120 mm h-1) and two slopes (10% and 20%) were studied. Overall, greater runoff, sediment and available nutrient losses occurred from the Cinnamon soil due to its greater soil erodibility, which was approximately 2.8 times greater than that of the Burozems soil. The influence of runoff on sediment was positively linear. The absolute slope of the regression line between runoff rate and sediment yield rate was suitable as a soil erodibility indicator. Runoff-associated AN and AP losses were mainly controlled by runoff rate, and were weakly affected by soil erodibility (p > 0.05). However, soil erodibility significantly influenced the sediment-associated AN and AP losses (p < 0.01), and a positive logarithmic correlation best described their relationships. Since the runoff-associated AN and AP losses dominated the total AN and AP losses for both soils, soil erodibility also exhibited negligible influence on the total AN and AP losses (p > 0.05). Increasing rainfall intensity and slope generally increased the runoff, sediment, and available nutrient losses for both soils, but had no significant influences on their relationships. Our results provide a better understanding of soil and nutrient loss mechanisms.

  1. [Factors affecting formation of THMs during dissolved organic nitrogen acetamide chlorination in drinking water].

    PubMed

    Chu, Wen-Hai; Gao, Nai-Yun; Zhao, Shi-Jia; Li, Qing-Song

    2009-05-15

    Chlorination disinfection greatly reduced bacteria and virus in drinking water. However, there is an unintended consequence of disinfection, the generation of chemical disinfection by-products (DBPs). Dissolved organic nitrogen (DON) as the important precursor of DBPs is of current concern. As acetamide (AcAm) occur in important bimolecular, we studied formation pathways for THMs during chlorination of model AcAm. The experiments are designed by Plackett-Burman and Box-Behnken methods. Factors affecting formation of THMs such as AcAm initial concentration, chlorine dosage, pH, temperature, Br(-) concentration and contact time were investigated. The results indicate that AcAm initial concentration, pH and temperature have little effects on formation of THMs. On the contrary, three other factors have important effects on formation of THMs, especially Br(-) concentration. The capacity of THMs generation varies very little when Br(-) has a constant concentration. Generation amount of THMs attach maximum under the condition that dosage of active chlorine, Br(-) concentration and contact time is 8.77 mg/L, 0.77 mg/L and 6.20 h respectively. Bromine ion plays a catalysis role on THMs formation. Controlling the concentration of bromine ion can reduce total generation amount of THMs via AcAm. Bromine partition coefficient tends to increasing along with contact time lapse. Controlling chlorination reaction time can lower the cancer risk. At last, the pathway is proposed for THMs formation via AcAm, and the catalysis mechanism of Br(-) was addressed.

  2. Ammonium-related metabolic changes affect somatic embryogenesis in pumpkin (Cucurbita pepo L.).

    PubMed

    Mihaljević, Snježana; Radić, Sandra; Bauer, Nataša; Garić, Rade; Mihaljević, Branka; Horvat, Gordana; Leljak-Levanić, Dunja; Jelaska, Sibila

    2011-11-01

    Somatic embryogenesis in pumpkin can be induced on auxin-containing medium and also on hormone-free medium containing 1mM ammonium (NH(4)(+)) as the sole source of nitrogen. Growth of NH(4)(+)-induced embryogenic tissue was slow and caused considerable acidification of the culture medium. Small spherical cells with dense cytoplasma formed proembryogenic cell clusters that could not develop into late stage embryos. Buffering of NH(4)(+) medium with 25mM 2-(N-morpholino)-ethane-sulfonic acid enhanced tissue proliferation, but no further differentiation was observed. Later stage embryos developed only after re-supply of nitrogen in form of nitrate or l-glutamine. Effects of nitrogen status and pH of culture media on ammonium assimilation were analyzed by following the activity of glutamine synthetase (GS) in relation to phenylalanine ammonia-lyase (PAL). Increased activity of GS and PAL in NH(4)(+) induced tissue coincided with significantly higher activity of stress-related enzymes superoxide dismutase (SOD) and soluble peroxidase (POD), indicating oxidative stress response of embryogenic tissue to NH(4)(+) as the sole source of nitrogen. In addition, considerable increase was observed in callose accumulation and esterase activity, the early markers of somatic embryogenesis. Activity of stress-related enzymes decreased after the re-supply of nitrate (20mM) or Gln (10mM) in combination with NH(4)(+) (1mM), which subsequently triggered globular embryo development. Together, these results suggest that stress responses, as affected by nitrogen supply, contribute to the regulation of embryogenic competence in pumpkin.

  3. Effect of the Ratio of Non-fibrous Carbohydrates to Neutral Detergent Fiber and Protein Structure on Intake, Digestibility, Rumen Fermentation, and Nitrogen Metabolism in Lambs.

    PubMed

    Ma, T; Tu, Y; Zhang, N F; Deng, K D; Diao, Q Y

    2015-10-01

    This study aimed to investigate the effect of the ratio of non-fibrous carbohydrates to neutral detergent fibre (NFC/NDF) and undegraded dietary protein (UDP) on rumen fermentation and nitrogen metabolism in lambs. Four Dorper×thin-tailed Han crossbred lambs, averaging 62.3±1.9 kg of body weight and 10 mo of age, were randomly assigned to four dietary treatments of combinations of two levels of NFC/NDF (1.0 and 1.7) and two levels of UDP (35% and 50% of crude protein [CP]). Duodenal nutrient flows were measured with dual markers of Yb and Co, and microbial N (MN) synthesis was estimated using (15)N. High UDP decreased organic matter (OM) intake (p = 0.002) and CP intake (p = 0.005). Ruminal pH (p<0.001), ammonia nitrogen (NH3-N; p = 0.008), and total volatile fatty acids (p<0.001) were affected by dietary NFC/NDF. The ruminal concentration of NH3-N was also affected by UDP (p<0.001). The duodenal flow of total MN (p = 0.007) was greater for lambs fed the high NFC/NDF diet. The amount of metabolisable N increased with increasing dietary NFC:NDF (p = 0.02) or UDP (p = 0.04). In conclusion, the diets with high NFC/NDF (1.7) and UDP (50% of CP) improved metabolisable N supply to lambs.

  4. Transcription Interference and ORF Nature Strongly Affect Promoter Strength in a Reconstituted Metabolic Pathway

    PubMed Central

    Carquet, Marie; Pompon, Denis; Truan, Gilles

    2015-01-01

    Fine tuning of individual enzyme expression level is necessary to alleviate metabolic imbalances in synthetic heterologous pathways. A known approach consists of choosing a suitable combination of promoters, based on their characterized strengths in model conditions. We questioned whether each step of a multiple-gene synthetic pathway could be independently tunable at the transcription level. Three open reading frames, coding for enzymes involved in a synthetic pathway, were combinatorially associated to different promoters on an episomal plasmid in Saccharomyces cerevisiae. We quantified the mRNA levels of the three genes in each strain of our generated combinatorial metabolic library. Our results evidenced that the ORF nature, position, and orientation induce strong discrepancies between the previously reported promoters’ strengths and the observed ones. We conclude that, in the context of metabolic reconstruction, the strength of usual promoters can be dramatically affected by many factors. Among them, transcriptional interference and ORF nature seem to be predominant. PMID:25767795

  5. Effects of feeding and confinement on nitrogen metabolism and excretion in the gulf toadfish Opsanus beta

    PubMed

    Walsh; Milligan

    1995-01-01

    In order to elucidate further the cues for, and the biochemical mechanisms of, the transition to ureogenesis in the gulf toadfish Opsanus beta, experiments on the effects of feeding (i.e. nitrogen loading) were carried out. Baseline nitrogen excretion rates were first measured on solitary toadfish in large water volumes (i.e. unconfined conditions). These nitrogen excretion rates were higher, and had a higher proportion as ammonia (61 %), than previously published 'control' measurements. Feeding of unconfined toadfish elevated total nitrogen excretion approximately threefold, with little change in the proportion of urea versus ammonia. During the first 24 h of confinement of unfed toadfish, absolute levels of urea excretion remained constant while ammonia excretion rates fell to near zero, so that toadfish became 90 % ureotelic. When fed prior to confinement, urea excretion rates remained constant for the first 24 h, and the bulk of the nitrogen was excreted as ammonia (80 %); excretion of the excess dietary nitrogen took up to 48 h to complete. If pre-adapted to confinement and then fed, toadfish excreted only about 55 % of their nitrogenous waste as ammonia, and excretion of excess dietary nitrogen was completed by 24 h. Elevations of hepatic glutamine synthetase (GNS) activities accompanied confinement and were shown to be almost exclusively in the cytosolic compartment and to be correlated with a decrease in the ratio of hepatic levels of glutamate:glutamine. These GNS activity increases also appear to account in part for the decrease in the percentage of ammoniotely in toadfish under conditions of nitrogen loading after confinement. However, additional means of regulating total nitrogen excretion (e.g. changes in protein turnover rates) and the degree of ureogenesis versus ammoniogenesis (e.g. N-acetylglutamate stimulation of carbamoylphosphate synthetase) must be postulated to account fully for changes in nitrogen excretion rates and activation of ureogenesis

  6. How interacting fungal species and mineral nitrogen inputs affect transfer of nitrogen from litter via arbuscular mycorrhizal mycelium.

    PubMed

    He, Yuejun; Cornelissen, J Hans C; Zhong, Zhangcheng; Dong, Ming; Jiang, Changhong

    2017-04-01

    In the karst landscape, widespread in the world including southern China, soil nutrient supply is strongly constrained. In such environments, arbuscular mycorrhizal (AM) fungi may facilitate plant nutrient uptake. However, the possible role of different AM fungal species, and their interactions, especially in transferring nitrogen (N) from litter to plant, is poorly understood. We conducted two microcosm experiments to investigate the role that two karst soil AM fungi, Glomus etunicatum and Glomus mosseae, play in the transfer of N from decomposing litter to the host plant and to determine how N availability influences these processes. In experiment 1, Cinnamomum camphora tree seedlings were grown in compartments inoculated with G. etunicatum. Lolium perenne leaf litter labeled with δ(15)N was added to the soil in unplanted compartments. Compartments containing the δ(15)N labeled litter were either accessible to hyphae but not to seedling roots or were not accessible to hyphae or roots. The addition of mineral N to one of the host compartments at the start of the experiment significantly increased the biomass of the C. camphora seedlings, N content and N:P ratio, AM mycelium length, and soil microbial biomass carbon and N. However, significantly, more δ(15)N was acquired, from the leaf litter by the AM hyphae and transferred to the host when mineral N was not added to the soil. In experiment 2, in which C. camphora seedlings were inoculated with both G. etunicatum and G. mosseae rather than with G. mosseae alone, there was a significant increase in mycelial growth (50.21%), in soil microbial biomass carbon (417.73%) in the rhizosphere, and in the amount of δ(15)N that was transferred to the host. These findings suggest that maintaining AM fungal diversity in karst soils could be important for mediating N transfer from organic material to host plants in N-poor soils.

  7. Olanzapine and aripiprazole differentially affect glucose uptake and energy metabolism in human mononuclear blood cells.

    PubMed

    Stapel, Britta; Kotsiari, Alexandra; Scherr, Michaela; Hilfiker-Kleiner, Denise; Bleich, Stefan; Frieling, Helge; Kahl, Kai G

    2017-05-01

    The use of antipsychotics carries the risk of metabolic side effects, such as weight gain and new onset type-2 diabetes mellitus. The mechanisms of the observed metabolic alterations are not fully understood. We compared the effects of two atypical antipsychotics, one known to favor weight gain (olanzapine), the other not (aripiprazole), on glucose metabolism. Primary human peripheral blood mononuclear cells (PBMC) were isolated and stimulated with olanzapine or aripiprazole for 72 h. Cellular glucose uptake was analyzed in vitro by 18F-FDG uptake. Further measurements comprised mRNA expression of glucose transporter (GLUT) 1 and 3, GLUT1 protein expression, DNA methylation of GLUT1 promoter region, and proteins involved in downstream glucometabolic processes. We observed a 2-fold increase in glucose uptake after stimulation with aripiprazole. In contrast, olanzapine stimulation decreased glucose uptake by 40%, accompanied by downregulation of the cellular energy sensor AMP activated protein kinase (AMPK). GLUT1 protein expression increased, GLUT1 mRNA expression decreased, and GLUT1 promoter was hypermethylated with both antipsychotics. Pyruvat-dehydrogenase (PDH) complex activity decreased with olanzapine only. Our findings suggest that the atypical antipsychotics olanzapine and aripiprazole differentially affect energy metabolism in PBMC. The observed decrease in glucose uptake in olanzapine stimulated PBMC, accompanied by decreased PDH point to a worsening in cellular energy metabolism not compensated by AMKP upregulation. In contrast, aripiprazole stimulation lead to increased glucose uptake, while not affecting PDH complex expression. The observed differences may be involved in the different metabolic profiles observed in aripiprazole and olanzapine treated patients.

  8. Calcium involved in the poly(γ-glutamic acid)-mediated promotion of Chinese cabbage nitrogen metabolism.

    PubMed

    Xu, Zongqi; Lei, Peng; Feng, Xiaohai; Xu, Xianju; Liang, Jinfeng; Chi, Bo; Xu, Hong

    2014-07-01

    Plant growth can reportedly be promoted by poly(γ-glutamic acid) (γ-PGA). However, the underlying mechanism is unknown. To reveal the mechanism of γ-PGA, we designed an experiment that investigated the effect of γ-PGA on the nitrogen metabolism of Chinese cabbage hydroponic cultured at different calcium (Ca) levels and varied exogenous Ca(2+) inhibitors. The results showed that nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase, and glutamate dehydrogenase activities in leaves and roots were obviously enhanced by γ-PGA at the normal Ca(2+) level (4.0 mM). Meanwhile, γ-PGA increased the content of total nitrogen, soluble protein, and soluble amino acids in leaves. However, the promotional effect of γ-PGA on fresh weight weakened when Ca(2+) was inadequate. Moreover, γ-PGA not only induced the influx of extracellular Ca(2+) and Ca(2+) in organelles into cytoplasm, but also increased the Ca(2+)-ATPase level to modify Ca(2+) homeostasis in plant cells. In addition, exogenous Ca(2+) inhibitors significantly suppressed the γ-PGA-mediated promotion of cytoplasmic free Ca(2+) level, calmodulin (CaM) content, GS and glutamate dehydrogenase activities. In summary, γ-PGA accelerated the nitrogen metabolism of plants through the Ca(2+)/CaM signaling pathway, thereby improving the growth of the plant.

  9. Metabolite Profiling and Integrative Modeling Reveal Metabolic Constraints for Carbon Partitioning under Nitrogen Starvation in the Green Algae Haematococcus pluvialis*

    PubMed Central

    Recht, Lee; Töpfer, Nadine; Batushansky, Albert; Sikron, Noga; Gibon, Yves; Fait, Aaron; Nikoloski, Zoran; Boussiba, Sammy; Zarka, Aliza

    2014-01-01

    The green alga Hematococcus pluvialis accumulates large amounts of the antioxidant astaxanthin under inductive stress conditions, such as nitrogen starvation. The response to nitrogen starvation and high light leads to the accumulation of carbohydrates and fatty acids as well as increased activity of the tricarboxylic acid cycle. Although the behavior of individual pathways has been well investigated, little is known about the systemic effects of the stress response mechanism. Here we present time-resolved metabolite, enzyme activity, and physiological data that capture the metabolic response of H. pluvialis under nitrogen starvation and high light. The data were integrated into a putative genome-scale model of the green alga to in silico test hypotheses of underlying carbon partitioning. The model-based hypothesis testing reinforces the involvement of starch degradation to support fatty acid synthesis in the later stages of the stress response. In addition, our findings support a possible mechanism for the involvement of the increased activity of the tricarboxylic acid cycle in carbon repartitioning. Finally, the in vitro experiments and the in silico modeling presented here emphasize the predictive power of large scale integrative approaches to pinpoint metabolic adjustment to changing environments. PMID:25183014

  10. Metabolite profiling and integrative modeling reveal metabolic constraints for carbon partitioning under nitrogen starvation in the green algae Haematococcus pluvialis.

    PubMed

    Recht, Lee; Töpfer, Nadine; Batushansky, Albert; Sikron, Noga; Gibon, Yves; Fait, Aaron; Nikoloski, Zoran; Boussiba, Sammy; Zarka, Aliza

    2014-10-31

    The green alga Hematococcus pluvialis accumulates large amounts of the antioxidant astaxanthin under inductive stress conditions, such as nitrogen starvation. The response to nitrogen starvation and high light leads to the accumulation of carbohydrates and fatty acids as well as increased activity of the tricarboxylic acid cycle. Although the behavior of individual pathways has been well investigated, little is known about the systemic effects of the stress response mechanism. Here we present time-resolved metabolite, enzyme activity, and physiological data that capture the metabolic response of H. pluvialis under nitrogen starvation and high light. The data were integrated into a putative genome-scale model of the green alga to in silico test hypotheses of underlying carbon partitioning. The model-based hypothesis testing reinforces the involvement of starch degradation to support fatty acid synthesis in the later stages of the stress response. In addition, our findings support a possible mechanism for the involvement of the increased activity of the tricarboxylic acid cycle in carbon repartitioning. Finally, the in vitro experiments and the in silico modeling presented here emphasize the predictive power of large scale integrative approaches to pinpoint metabolic adjustment to changing environments.

  11. Carbon and nitrogen provisions alter the metabolic flux in developing soybean embryos

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybeans store approximately 40% of their biomass in the form of protein. Protein concentrations reflect the carbon and nitrogen levels received by the developing embryo. The relationship between carbon and nitrogen supply and seed composition during filling was examined through a series of embryo c...

  12. Nitrogen Fertilizer Dependency and Its Contradictions: A Theoretical Exploration of Social-Ecological Metabolism

    ERIC Educational Resources Information Center

    Mancus, Philip

    2007-01-01

    The global agro-food system relies heavily on inorganic nitrogenous fertilizers. In addition to consuming enormous amounts of energy, this manufactured input contributes to the accumulation of reactive nitrogen in the biosphere and undermines the biological basis of agricultural production itself. While technological inefficiency and population…

  13. Cardiac Metabolic Pathways Affected in the Mouse Model of Barth Syndrome

    PubMed Central

    Huang, Yan; Powers, Corey; Madala, Satish K.; Greis, Kenneth D.; Haffey, Wendy D.; Towbin, Jeffrey A.; Purevjav, Enkhsaikhan; Javadov, Sabzali; Strauss, Arnold W.; Khuchua, Zaza

    2015-01-01

    Cardiolipin (CL) is a mitochondrial phospholipid essential for electron transport chain (ETC) integrity. CL-deficiency in humans is caused by mutations in the tafazzin (Taz) gene and results in a multisystem pediatric disorder, Barth syndrome (BTHS). It has been reported that tafazzin deficiency destabilizes mitochondrial respiratory chain complexes and affects supercomplex assembly. The aim of this study was to investigate the impact of Taz-knockdown on the mitochondrial proteomic landscape and metabolic processes, such as stability of respiratory chain supercomplexes and their interactions with fatty acid oxidation enzymes in cardiac muscle. Proteomic analysis demonstrated reduction of several polypeptides of the mitochondrial respiratory chain, including Rieske and cytochrome c1 subunits of complex III, NADH dehydrogenase alpha subunit 5 of complex I and the catalytic core-forming subunit of F0F1-ATP synthase. Taz gene knockdown resulted in upregulation of enzymes of folate and amino acid metabolic pathways in heart mitochondria, demonstrating that Taz-deficiency causes substantive metabolic remodeling in cardiac muscle. Mitochondrial respiratory chain supercomplexes are destabilized in CL-depleted mitochondria from Taz knockdown hearts resulting in disruption of the interactions between ETC and the fatty acid oxidation enzymes, very long-chain acyl-CoA dehydrogenase and long-chain 3-hydroxyacyl-CoA dehydrogenase, potentially affecting the metabolic channeling of reducing equivalents between these two metabolic pathways. Mitochondria-bound myoglobin was significantly reduced in Taz-knockdown hearts, potentially disrupting intracellular oxygen delivery to the oxidative phosphorylation system. Our results identify the critical pathways affected by the Taz-deficiency in mitochondria and establish a future framework for development of therapeutic options for BTHS. PMID:26030409

  14. Cardiac metabolic pathways affected in the mouse model of barth syndrome.

    PubMed

    Huang, Yan; Powers, Corey; Madala, Satish K; Greis, Kenneth D; Haffey, Wendy D; Towbin, Jeffrey A; Purevjav, Enkhsaikhan; Javadov, Sabzali; Strauss, Arnold W; Khuchua, Zaza

    2015-01-01

    Cardiolipin (CL) is a mitochondrial phospholipid essential for electron transport chain (ETC) integrity. CL-deficiency in humans is caused by mutations in the tafazzin (Taz) gene and results in a multisystem pediatric disorder, Barth syndrome (BTHS). It has been reported that tafazzin deficiency destabilizes mitochondrial respiratory chain complexes and affects supercomplex assembly. The aim of this study was to investigate the impact of Taz-knockdown on the mitochondrial proteomic landscape and metabolic processes, such as stability of respiratory chain supercomplexes and their interactions with fatty acid oxidation enzymes in cardiac muscle. Proteomic analysis demonstrated reduction of several polypeptides of the mitochondrial respiratory chain, including Rieske and cytochrome c1 subunits of complex III, NADH dehydrogenase alpha subunit 5 of complex I and the catalytic core-forming subunit of F0F1-ATP synthase. Taz gene knockdown resulted in upregulation of enzymes of folate and amino acid metabolic pathways in heart mitochondria, demonstrating that Taz-deficiency causes substantive metabolic remodeling in cardiac muscle. Mitochondrial respiratory chain supercomplexes are destabilized in CL-depleted mitochondria from Taz knockdown hearts resulting in disruption of the interactions between ETC and the fatty acid oxidation enzymes, very long-chain acyl-CoA dehydrogenase and long-chain 3-hydroxyacyl-CoA dehydrogenase, potentially affecting the metabolic channeling of reducing equivalents between these two metabolic pathways. Mitochondria-bound myoglobin was significantly reduced in Taz-knockdown hearts, potentially disrupting intracellular oxygen delivery to the oxidative phosphorylation system. Our results identify the critical pathways affected by the Taz-deficiency in mitochondria and establish a future framework for development of therapeutic options for BTHS.

  15. Bromochloromethane, a Methane Analogue, Affects the Microbiota and Metabolic Profiles of the Rat Gastrointestinal Tract

    PubMed Central

    Yang, Yu-Xiang; Mu, Chun-Long; Luo, Zhen

    2015-01-01

    Bromochloromethane (BCM), an inhibitor of methanogenesis, has been used in animal production. However, little is known about its impact on the intestinal microbiota and metabolic patterns. The present study aimed to investigate the effect of BCM on the colonic bacterial community and metabolism by establishing a Wistar rat model. Twenty male Wistar rats were randomly divided into two groups (control and treated with BCM) and raised for 6 weeks. Bacterial fermentation products in the cecum were determined, and colonic methanogens and sulfate-reducing bacteria (SRB) were quantified. The colonic microbiota was analyzed by pyrosequencing of the 16S rRNA genes, and metabolites were profiled by gas chromatography and mass spectrometry. The results showed that BCM did not affect body weight and feed intake, but it did significantly change the intestinal metabolic profiles. Cecal protein fermentation was enhanced by BCM, as methylamine, putrescine, phenylethylamine, tyramine, and skatole were significantly increased. Colonic fatty acid and carbohydrate concentrations were significantly decreased, indicating the perturbation of lipid and carbohydrate metabolism by BCM. BCM treatment decreased the abundance of methanogen populations, while SRB were increased in the colon. BCM did not affect the total colonic bacterial counts but significantly altered the bacterial community composition by decreasing the abundance of actinobacteria, acidobacteria, and proteobacteria. The results demonstrated that BCM treatment significantly altered the microbiotic and metabolite profiles in the intestines, which may provide further information on the use of BCM in animal production. PMID:26567308

  16. ADP-glucose pyrophosphorylase-deficient pea embryos reveal specific transcriptional and metabolic changes of carbon-nitrogen metabolism and stress responses.

    PubMed

    Weigelt, Kathleen; Küster, Helge; Rutten, Twan; Fait, Aaron; Fernie, Alisdair R; Miersch, Otto; Wasternack, Claus; Emery, R J Neil; Desel, Christine; Hosein, Felicia; Müller, Martin; Saalbach, Isolde; Weber, Hans

    2009-01-01

    We present a comprehensive analysis of ADP-glucose pyrophosphorylase (AGP)-repressed pea (Pisum sativum) seeds using transcript and metabolite profiling to monitor the effects that reduced carbon flow into starch has on carbon-nitrogen metabolism and related pathways. Changed patterns of transcripts and metabolites suggest that AGP repression causes sugar accumulation and stimulates carbohydrate oxidation via glycolysis, tricarboxylic acid cycle, and mitochondrial respiration. Enhanced provision of precursors such as acetyl-coenzyme A and organic acids apparently support other pathways and activate amino acid and storage protein biosynthesis as well as pathways fed by cytosolic acetyl-coenzyme A, such as cysteine biosynthesis and fatty acid elongation/metabolism. As a consequence, the resulting higher nitrogen (N) demand depletes transient N storage pools, specifically asparagine and arginine, and leads to N limitation. Moreover, increased sugar accumulation appears to stimulate cytokinin-mediated cell proliferation pathways. In addition, the deregulation of starch biosynthesis resulted in indirect changes, such as increased mitochondrial metabolism and osmotic stress. The combined effect of these changes is an enhanced generation of reactive oxygen species coupled with an up-regulation of energy-dissipating, reactive oxygen species protection, and defense genes. Transcriptional activation of mitogen-activated protein kinase pathways and oxylipin synthesis indicates an additional activation of stress signaling pathways. AGP-repressed embryos contain higher levels of jasmonate derivatives; however, this increase is preferentially in nonactive forms. The results suggest that, although metabolic/osmotic alterations in iAGP pea seeds result in multiple stress responses, pea seeds have effective mechanisms to circumvent stress signaling under conditions in which excessive stress responses and/or cellular damage could prematurely initiate senescence or apoptosis.

  17. How Subduction Settings can Affect Planetary Nitrogen Cycle: An Experimental Insight

    NASA Astrophysics Data System (ADS)

    Cedeno, D. G.; Conceicao, R. V.; Wilbert de Souza, M. R.; Carniel, L. C.; Schmitz Quinteiro, R. V.

    2015-12-01

    Nitrogen is one of the main building blocks of life on Earth and its elemental cycle is deeply connected with organic matter and the biological system. It is known that nitrogen can be stored in mantellic phases (such as clinopyroxenes) or in metallic alloys under high pressures, meaning that Earth's mantle, and even the core, could be efficient nitrogen reservoirs. Probably, nitrogen is present in these deep Earth systems since the formation of our planet. Nevertheless, it is possible that superficial nitrogen can be reintroduced in the mantle through tectonic processes along Earth history. This is reinforced by d15N values in inclusions in diamonds and other deep mantle phases. We believe that subduction zones are efficient enough to transport nitrogen from surface to mantle. Clay minerals with high charge exchange capacity (CEC) are good candidates to convey nitrogen in subduction zones, especially when we take into account the similarities between K+ and NH4+. To simulate the high-pressure high-temperature conditions found in subduction zones, we performed a series of experiments with montmorillonite clay mineral undergone to high pressure and high temperature produced by a hydraulic press coupled with toroidal chambers, in pressures ranging from 2.5 to 7.7 GPa and temperatures up to 700oC. We used ex situ XRD analysis to accompany the main montmorillonite structural changes and FTIR analysis to determine quantitatively the presence of nitrogen. So far, our results show that the main structural transition in montmorillonite happens at ~350oC at room pressure and ~450oC at 2.5 and 4.0 GPa and consists in the transformation of an open clay structure to a closed mica structure (tobelite). FTIR data show the presence of nitrogen in all the analysed experiments. With the data obtained, we can presume that clay minerals carried in subduction zones can successfully transport nitrogen and other volatiles to the mantle. However, only cold subduction systems have the

  18. Visualizing Single Cell Biology: Nanosims Studies of Carbon and Nitrogen Metabolism in Diazotrophic Cyanobacteria

    NASA Astrophysics Data System (ADS)

    Pett-Ridge, J.; Finzi, J. A.; Capone, D. G.; Popa, R.; Nealson, K. H.; Ng, W.; Spormann, A. M.; Hutcheon, I. D.; Weber, P. K.

    2007-12-01

    Filamentous nitrogen fixing (diazotrophic) cyanobacteria are key players in global nutrient cycling, but the relationship between CO2- and N2-fixation and intercellular exchange of these elements remains poorly understood in many genera. These bacteria are faced with the challenge of isolating regions of N-fixation (O2 inhibited) and photosynthetic (O2 producing) activity. We used isotope labeling in conjunction with a high-resolution isotope and elemental mapping technique (NanoSIMS) to quantitatively describe 13C and 15N uptake and transport in two aquatic cyanobacteria grown on NaH13CO3 and 15N2. The technical challenges of tracing isotopes within individual bacteria can be overcome with high resolution Secondary Ion Mass Spectrometry (NanoSIMS). In NanoSIMS analysis, samples are sputtered with an energetic primary beam (Cs+, O-) liberating secondary ions that are separated by the mass spectrometer and detected in a suite of electron multipliers. Five isotopic species may be analyzed concurrently with spatial resolution as fine as 50nm. A high sensitivity isotope ratio 'map' can then be generated for the analyzed area. Using sequentially harvested cyanobacteria in conjunction with enriched H13CO3 and 15N2 incubations, we measured temporal enrichment patterns that evolve over the course of a day's growth and suggest tightly regulated changes in fixation kinetics. With a combination of TEM, SEM and NanoSIMS analyses, we also mapped the distribution of C, N and Mo (a critical nitrogenase co-factor) isotopes in intact cells. Our results suggest that NanoSIMS mapping of metal enzyme co-factors may be a powerful method of identifying physiological and morphological characteristics within individual bacterial cells, and could be used to provide a 3-dimensional context for more traditional analyses such as immunogold labeling. Finally, we resolved patterns of isotope enrichment at multiple spatial scales: sub-cellular variation, cell-cell differences along filaments

  19. Nitrogen and carbon source balance determines longevity, independently of fermentative or respiratory metabolism in the yeast Saccharomyces cerevisiae.

    PubMed

    Santos, Júlia; Leitão-Correia, Fernanda; Sousa, Maria João; Leão, Cecília

    2016-04-26

    Dietary regimens have proven to delay aging and age-associated diseases in several eukaryotic model organisms but the input of nutritional balance to longevity regulation is still poorly understood. Here, we present data on the role of single carbon and nitrogen sources and their interplay in yeast longevity. Data demonstrate that ammonium, a rich nitrogen source, decreases chronological life span (CLS) of the prototrophic Saccharomyces cerevisiae strain PYCC 4072 in a concentration-dependent manner and, accordingly, that CLS can be extended through ammonium restriction, even in conditions of initial glucose abundance. We further show that CLS extension depends on initial ammonium and glucose concentrations in the growth medium, as long as other nutrients are not limiting. Glutamine, another rich nitrogen source, induced CLS shortening similarly to ammonium, but this effect was not observed with the poor nitrogen source urea. Ammonium decreased yeast CLS independently of the metabolic process activated during aging, either respiration or fermentation, and induced replication stress inhibiting a proper cell cycle arrest in G0/G1 phase. The present results shade new light on the nutritional equilibrium as a key factor on cell longevity and may contribute for the definition of interventions to promote life span and healthy aging.

  20. A comparison of nitrogen utilization and urea metabolism between Tibetan and fine-wool sheep.

    PubMed

    Zhou, J W; Mi, J D; Titgemeyer, E C; Guo, X S; Ding, L M; Wang, H C; Qiu, Q; Li, Z P; Long, R J

    2015-06-01

    To study metabolic adaptation to harsh foraging conditions, an experiment was conducted to characterize and quantify N utilization efficiency and urea metabolism in Tibetan and fine-wool sheep fed 4 levels of dietary N (11.0, 16.7, 23.1, and 29.2 g N/kg DM) in 2 concurrent 4 × 4 Latin square designs. Urea kinetics were determined using continuous intrajugular infusions of 15N15N-urea. Urinary excretions of total N and urea N increased linearly (P < 0.001) with dietary N and were not different between breeds (P ≥ 0.37). Fecal N excretion increased with dietary N for Tibetan sheep but not for fine-wool sheep (linear dietary N × breed; P < 0.05). Nitrogen retention (both amount per day and percentage of N intake) increased with increasing dietary N concentration (P < 0.001), and the rates of increase were greater in fine-wool than in Tibetan sheep (linear dietary N × breed and cubic dietary N × breed; P < 0.05). In Tibetan sheep, N retention as a percentage of intake was greatest for diets containing 16.7 g N/kg DM, whereas it was maximal for fine-wool sheep when the diet contained 23.1 g N/kg DM. Urea N entry rate, urea N recycled to the gastrointestinal tract (GIT), and urea N returned to the ornithine cycle all increased with dietary N (P < 0.05), and all were greater in Tibetan than fine-wool sheep for the 11.0 g N/kg DM diet but were greater in fine-wool than Tibetan sheep for the diet with 29.2 g N/kg DM (linear dietary N × breed; P < 0.05). Urea N excreted in feces, both amount and fraction of GIT entry rate, was less in Tibetan than fine-wool sheep for the 11.0 and 16.7 g N/kg DM diets but similar for diets with 23.1 or 29.2 g N/kg DM (linear dietary N × breed; P < 0.01). For the lowest-protein diet, the fraction of urea N production recycled to the GIT was greater in the Tibetan than fine-wool sheep (88% vs. 82%), but for the diet with 29.2 g N/kg DM it was greater for fine-wool than Tibetan sheep (46% vs. 39%; linear dietary N × breed; P < 0

  1. Respiratory nitrogen metabolism and nitrosative stress defence in ϵ-proteobacteria: the role of NssR-type transcription regulators.

    PubMed

    Kern, Melanie; Winkler, Christine; Simon, Jörg

    2011-01-01

    ϵ-Proteobacteria form a globally ubiquitous group of ecologically significant organisms and comprise a diverse range of host-associated and free-living species. To grow by anaerobic respiration, many ϵ-proteobacteria reduce nitrate to nitrite followed by either nitrite ammonification or denitrification. Using the ammonifying model organisms Wolinella succinogenes and Campylobacter jejuni, the electron transport chains of nitrate respiration, respiratory nitrite ammonification and even N2O (nitrous oxide) respiration have been characterized in recent years, but knowledge on nitrosative stress defence, nitrogen compound-sensing and corresponding signal transduction pathways is limited. The potentially dominant role of NssR (nitrosative stress-sensing regulator)-type transcription regulators in ϵ-proteobacterial nitrogen metabolism is discussed.

  2. Nitrification-driven forms of nitrogen metabolism in microbial mat communities thriving along an ammonium-enriched subsurface geothermal stream

    NASA Astrophysics Data System (ADS)

    Nishizawa, Manabu; Koba, Keisuke; Makabe, Akiko; Yoshida, Naohiro; Kaneko, Masanori; Hirao, Shingo; Ishibashi, Jun-ichiro; Yamanaka, Toshiro; Shibuya, Takazo; Kikuchi, Tohru; Hirai, Miho; Miyazaki, Junichi; Nunoura, Takuro; Takai, Ken

    2013-07-01

    We report here the concurrence and interaction among forms of nitrogen metabolism in thermophilic microbial mat communities that developed in an ammonium-abundant subsurface geothermal stream. First, the physical and chemical conditions of the stream water at several representative microbial mat habitats (including upper, middle and downstream sites) were characterized. A thermodynamic calculation using these physical and chemical conditions predicted that nitrification consisting of ammonia and nitrite oxidations would provide one of the largest energy yields of chemolithotrophic metabolisms. Second, near-complete prokaryotic 16S rRNA gene clone analysis was conducted for representative microbial mat communities at the upper, middle and downstream sites. The results indicated a dynamic shift in the 16S rRNA gene phylotype composition through physical and chemical variations of the stream water. The predominant prokaryotic components varied from phylotypes related to hydrogeno (H2)- and thio (S)-trophic Aquificales, thermophilic methanotrophs and putative ammonia-oxidizing Archaea (AOA) located upstream (72 °C) to the phylotypes affiliated with putative AOA and nitrite-oxidizing bacteria (NOB) located at the middle and downstream sites (65 and 57 °C, respectively). In addition, the potential in situ metabolic activities of different forms of nitrogen metabolism were estimated through laboratory experiments using bulk microbial mat communities. Finally, the compositional and isotopic variation in nitrogen compounds was investigated in the stream water flowing over the microbial mats and in the interstitial water inside the mats. Although the stream water was characterized by a gradual decrease in the total ammonia concentration (ΣNH3: the sum of ammonia and ammonium concentrations) and a gradual increase in the total concentration of nitrite and nitrate (NO2- + NO3-), the total inorganic nitrogen concentration (TIN: the sum of ΣNH3, NO2- and NO3- concentrations

  3. A NAC for regulating metabolism: the nitrogen assimilation control protein (NAC) from Klebsiella pneumoniae.

    PubMed

    Bender, Robert A

    2010-10-01

    The nitrogen assimilation control protein (NAC) is a LysR-type transcriptional regulator (LTTR) that is made under conditions of nitrogen-limited growth. NAC's synthesis is entirely dependent on phosphorylated NtrC from the two-component Ntr system and requires the unusual sigma factor σ54 for transcription of the nac gene. NAC activates the transcription of σ70-dependent genes whose products provide the cell with ammonia or glutamate. NAC represses genes whose products use ammonia and also represses its own transcription. In addition, NAC also subtly adjusts other cellular functions to keep pace with the supply of biosynthetically available nitrogen.

  4. Visible injury and nitrogen metabolism of rice leaves under ozone stress, and effect on sugar and protein contents in grain

    NASA Astrophysics Data System (ADS)

    Huang, Y. Z.; Sui, L. H.; Wang, W.; Geng, C. M.; Yin, B. H.

    2012-12-01

    Effect of ozone on the visible injury, nitrogen metabolism of rice leaves, and sugar and protein contents in rice grain was carried out by the open-top chamber. The results indicated that ozone stress caused obvious injury in rice leaves. The increase in ozone concentration had significant influence on the nitrate reductase activity in rice leaves. At the ozone concentration of 40, 80 and 120 nL L-1, the nitrate reductase activities in rice leaves in the tillering stage, the jointing stage, the heading stage and milk stage were separately reduced by 25.3-86.3%, 57.4-97.8%, 91.0-99.3% and 89.5-96.7% compared with those in the control treatment. As ozone concentration increased, the contents of ammonium nitrogen and nitrate nitrogen in rice leaves were obviously reduced. Ozone stress also had an influence on the contents of sugar and protein in rice grain. The stress of high ozone concentration (120 nL L-1) caused the starch content in grain to reduce by 15.8% than that in the control treatment, but total soluble sugars in grain was actually enhanced by 47.5% compared to that in the control treatment. The contents of albumin and glutenin in rice grain increased with increasing the ozone concentration, and prolamin and crude protein contents in rice grain increased only at the higher ozone concentration. Under ozone concentration of 120 nL L-1, the contents of albumin, glutenin and crude protein in rice grain were increased respectively by 23.1%, 21.0% and 21.1% compared with those in the control treatment. The result suggested that ozone tress has an influence on nitrogen metabolism of rice leaves and grain quality.

  5. Impaired glycogen synthesis causes metabolic overflow reactions and affects stress responses in the cyanobacterium Synechocystis sp. PCC 6803.

    PubMed

    Gründel, Marianne; Scheunemann, Ramon; Lockau, Wolfgang; Zilliges, Yvonne

    2012-12-01

    The biosynthesis of glycogen or starch is one of the main strategies developed by living organisms for the intracellular storage of carbon and energy. In phototrophic organisms, such polyglucans accumulate due to carbon fixation during photosynthesis and are used to provide maintenance energy for cell integrity, function and viability in dark periods. Moreover, it is assumed that glycogen enables cyanobacteria to cope with transient starvation conditions, as observed in most micro-organisms. Here, glycogen accumulates when an appropriate carbon source is available in sufficient amounts but growth is inhibited by lack of other nutrients. In this study, the role of glycogen in energy and carbon metabolism of phototrophic cyanobacteria was first analysed via a comparative physiological and metabolic characterization of knockout mutants defective in glycogen synthesis. We first proved the role of glycogen as a respiratory substrate in periods of darkness, the role of glycogen as a reserve to survive starvation periods such as nitrogen depletion and the role of glycogen synthesis as an ameliorator of carbon excess conditions in the model organism Synechocystis sp. PCC 6803. We provide striking new insights into the complex carbon and nitrogen metabolism of non-diazotrophic cyanobacteria: a phenotype of sensitivity to photomixotrophic conditions and of reduced glucose uptake, a non-bleaching phenotype based on an impaired acclimation response to nitrogen depletion and furthermore a phenotype of energy spilling. This study shows that the analysis of deficiencies in glycogen metabolism is a valuable tool for the identification of metabolic regulatory principles and signals.

  6. Climate change affects key nitrogen-fixing bacterial populations on coral reefs.

    PubMed

    Santos, Henrique F; Carmo, Flávia L; Duarte, Gustavo; Dini-Andreote, Francisco; Castro, Clovis B; Rosado, Alexandre S; van Elsas, Jan Dirk; Peixoto, Raquel S

    2014-11-01

    Coral reefs are at serious risk due to events associated with global climate change. Elevated ocean temperatures have unpredictable consequences for the ocean's biogeochemical cycles. The nitrogen cycle is driven by complex microbial transformations, including nitrogen fixation. This study investigated the effects of increased seawater temperature on bacteria able to fix nitrogen (diazotrophs) that live in association with the mussid coral Mussismilia harttii. Consistent increases in diazotroph abundances and diversities were found at increased temperatures. Moreover, gradual shifts in the dominance of particular diazotroph populations occurred as temperature increased, indicating a potential future scenario of climate change. The temperature-sensitive diazotrophs may provide useful bioindicators of the effects of thermal stress on coral reef health, allowing the impact of thermal anomalies to be monitored. In addition, our findings support the development of research on different strategies to improve the fitness of corals during events of thermal stress, such as augmentation with specific diazotrophs.

  7. Climate change affects key nitrogen-fixing bacterial populations on coral reefs

    PubMed Central

    Santos, Henrique F; Carmo, Flávia L; Duarte, Gustavo; Dini-Andreote, Francisco; Castro, Clovis B; Rosado, Alexandre S; van Elsas, Jan Dirk; Peixoto, Raquel S

    2014-01-01

    Coral reefs are at serious risk due to events associated with global climate change. Elevated ocean temperatures have unpredictable consequences for the ocean's biogeochemical cycles. The nitrogen cycle is driven by complex microbial transformations, including nitrogen fixation. This study investigated the effects of increased seawater temperature on bacteria able to fix nitrogen (diazotrophs) that live in association with the mussid coral Mussismilia harttii. Consistent increases in diazotroph abundances and diversities were found at increased temperatures. Moreover, gradual shifts in the dominance of particular diazotroph populations occurred as temperature increased, indicating a potential future scenario of climate change. The temperature-sensitive diazotrophs may provide useful bioindicators of the effects of thermal stress on coral reef health, allowing the impact of thermal anomalies to be monitored. In addition, our findings support the development of research on different strategies to improve the fitness of corals during events of thermal stress, such as augmentation with specific diazotrophs. PMID:24830827

  8. Genetic Variability in Nodulation and Root Growth Affects Nitrogen Fixation and Accumulation in Pea

    PubMed Central

    Bourion, Virginie; Laguerre, Gisele; Depret, Geraldine; Voisin, Anne-Sophie; Salon, Christophe; Duc, Gerard

    2007-01-01

    Background and Aims Legume nitrogen is derived from two different sources, symbiotically fixed atmospheric N2 and soil N. The effect of genetic variability of root and nodule establishment on N acquisition and seed protein yield was investigated under field conditions in pea (Pisum sativum). In addition, these parameters were related to the variability in preference for rhizobial genotypes. Methods Five different spring pea lines (two hypernodulating mutants and three cultivars), previously identified in artificial conditions as contrasted for both root and nodule development, were characterized under field conditions. Root and nodule establishment was examined from the four-leaf stage up to the beginning of seed filling and was related to the patterns of shoot dry matter and nitrogen accumulation. The genetic structure of rhizobial populations associated with the pea lines was obtained by analysis of nodule samples. The fraction of nitrogen derived from symbiotic fixation was estimated at the beginning of seed filling and at physiological maturity, when seed protein content and yield were determined. Key Results The hypernodulating mutants established nodules earlier and maintained them longer than was the case for the three cultivars, whereas their root development and nitrogen accumulation were lower. The seed protein yield was higher in ‘Athos’ and ‘Austin’, the two cultivars with increased root development, consistent with their higher N absorption during seed filling. Conclusion The hypernodulating mutants did not accumulate more nitrogen, probably due to the C cost for nodulation being higher than for root development. Enhancing exogenous nitrogen supply at the end of the growth cycle, by increasing the potential for root N uptake from soil, seems a good option for improving pea seed filling. PMID:17670753

  9. Performance and energy metabolism in restrictively fed weanling pigs are not affected by feeding either fermented cereals or their end-products.

    PubMed

    Bruininx, E M A M; Binnendijk, G P; Zandstra, T; Heetkamp, M J W; Van Der Peet-Schwering, C M C; Gerrits, W J J

    2010-12-01

    To study the effects of feeding fermented cereals or just fermentation end-products on performance and energy metabolism, 18 restrictedly fed groups of eight pigs each were assigned to one of three dietary treatments: (i) a liquid control diet (C) containing 40% of a mixture of barley and wheat; or (ii) a liquid diet (F) containing 40% fermented barley and wheat; or (iii) a liquid diet as C with the addition of some important fermentation end-products (FP; organic acids and ethanol) in concentrations similar to those in the fermented F-diet. Energy and nitrogen balances, heat production, and performance traits were measured during two consecutive periods (days 1-5 and days 6-14). There was a considerable increase in average dry matter intake that tended (p = 0.06) to be higher in the FP-group than in the other groups. Apparent fecal digestibility of dry matter, ash, nitrogen and energy during period 2 were not affected (p > 0.1). Averaged over both periods, none of the energy metabolism parameters were affected by the diets (p > 0.1). However, there were diet × period interactions for metabolizable energy-intake (p = 0.07), energy retention (p < 0.05), the respiratory quotient (RQ; p < 0.01) and activity-related heat production (H(ACT,) p = 0.05). Additionally, there were some differences between the diets in the average hourly patterns in RQ and H(ACT). In conclusion, restricted feeding of either 40% fermented cereals nor their fermentation end-products affected performance and energy metabolism traits in weanling pigs. Nevertheless, lower postprandial activity-related heat production by pigs given the fermented cereals suggest a stimulating effect of fermented cereals on short term satiety that was not seen in pigs given fermentation end-products only.

  10. Genetic modification of iron metabolism in mice affects the gut microbiota.

    PubMed

    Buhnik-Rosenblau, Keren; Moshe-Belizowski, Shirly; Danin-Poleg, Yael; Meyron-Holtz, Esther G

    2012-10-01

    The composition of the gut microbiota is affected by environmental factors as well as host genetics. Iron is one of the important elements essential for bacterial growth, thus we hypothesized that changes in host iron homeostasis, may affect the luminal iron content of the gut and thereby the composition of intestinal bacteria. The iron regulatory protein 2 (Irp2) and one of the genes mutated in hereditary hemochromatosis Hfe , are both proteins involved in the regulation of systemic iron homeostasis. To test our hypothesis, fecal metal content and a selected spectrum of the fecal microbiota were analyzed from Hfe-/-, Irp2-/- and their wild type control mice. Elevated levels of iron as well as other minerals in feces of Irp2-/- mice compared to wild type and Hfe-/- mice were observed. Interestingly significant variation in the general fecal-bacterial population-patterns was observed between Irp2-/- and Hfe-/- mice. Furthermore the relative abundance of five species, mainly lactic acid bacteria, was significantly different among the mouse lines. Lactobacillus (L.) murinus and L. intestinalis were highly abundant in Irp2-/- mice, Enterococcus faecium species cluster and a species most similar to Olsenella were highly abundant in Hfe-/- mice and L. johnsonii was highly abundant in the wild type mice. These results suggest that deletion of iron metabolism genes in the mouse host affects the composition of its intestinal bacteria. Further studying the relationship between gut microbiota and genetic mutations affecting systemic iron metabolism in human should lead to clinical implications.

  11. Zinc oxide nanoparticles affect carbon and nitrogen mineralization of Phoenix dactylifera leaf litter in a sandy soil.

    PubMed

    Rashid, Muhammad Imtiaz; Shahzad, Tanvir; Shahid, Muhammad; Ismail, Iqbal M I; Shah, Ghulam Mustafa; Almeelbi, Talal

    2017-02-15

    We investigated the impact of zinc oxide nanoparticles (ZnO NPs; 1000mgkg(-1) soil) on soil microbes and their associated soil functions such as date palm (Phoenix dactylifera) leaf litter (5gkg(-1) soil) carbon and nitrogen mineralization in mesocosms containing sandy soil. Nanoparticles application in litter-amended soil significantly decreased the cultivable heterotrophic bacterial and fungal colony forming units (cfu) compared to only litter-amended soil. The decrease in cfu could be related to lower microbial biomass carbon in nanoparticles-litter amended soil. Likewise, ZnO NPs also reduced CO2 emission by 10% in aforementioned treatment but this was higher than control (soil only). Labile Zn was only detected in the microbial biomass of nanoparticles-litter applied soil indicating that microorganisms consumed this element from freely available nutrients in the soil. In this treatment, dissolved organic carbon and mineral nitrogen were 25 and 34% lower respectively compared to litter-amended soil. Such toxic effects of nanoparticles on litter decomposition resulted in 130 and 122% lower carbon and nitrogen mineralization efficiency respectively. Hence, our results entail that ZnO NPs are toxic to soil microbes and affect their function i.e., carbon and nitrogen mineralization of applied litter thus confirming their toxicity to microbial associated soil functions.

  12. The soil carbon/nitrogen ratio and moisture affect microbial community structures in alkaline permafrost-affected soils with different vegetation types on the Tibetan plateau.

    PubMed

    Zhang, Xinfang; Xu, Shijian; Li, Changming; Zhao, Lin; Feng, Huyuan; Yue, Guangyang; Ren, Zhengwei; Cheng, Guogdong

    2014-01-01

    In the Tibetan permafrost region, vegetation types and soil properties have been affected by permafrost degradation, but little is known about the corresponding patterns of their soil microbial communities. Thus, we analyzed the effects of vegetation types and their covariant soil properties on bacterial and fungal community structure and membership and bacterial community-level physiological patterns. Pyrosequencing and Biolog EcoPlates were used to analyze 19 permafrost-affected soil samples from four principal vegetation types: swamp meadow (SM), meadow (M), steppe (S) and desert steppe (DS). Proteobacteria, Acidobacteria, Bacteroidetes and Actinobacteria dominated bacterial communities and the main fungal phyla were Ascomycota, Basidiomycota and Mucoromycotina. The ratios of Proteobacteria/Acidobacteria decreased in the order: SM>M>S>DS, whereas the Ascomycota/Basidiomycota ratios increased. The distributions of carbon and nitrogen cycling bacterial genera detected were related to soil properties. The bacterial communities in SM/M soils degraded amines/amino acids very rapidly, while polymers were degraded rapidly by S/DS communities. UniFrac analysis of bacterial communities detected differences among vegetation types. The fungal UniFrac community patterns of SM differed from the others. Redundancy analysis showed that the carbon/nitrogen ratio had the main effect on bacteria community structures and their diversity in alkaline soil, whereas soil moisture was mainly responsible for structuring fungal communities. Thus, microbial communities and their functioning are probably affected by soil environmental change in response to permafrost degradation.

  13. Summer legume 'green' nitrogen crops affect winter wheat forage in continuous rotations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Costs for inorganic nitrogen (N) fertilizers in the southern Great Plains (SGP) have increased in recent years with the rise in oil prices. In response, producers have become interested in the potential merits of using annual legumes as N sources. This study described the influence of two summer for...

  14. Green manures in continuous wheat systems affect grain yield and nitrogen content

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Continuous winter wheat (Triticum aestivum L. em Thell.) is the foundation for most U.S. southern Great Plains (SGP) agriculture. Inorganic nitrogen (N) fertilizers are important to wheat production, but increasing N prices have caused farmers to reconsider growing legumes during summer fallow for ‘...

  15. CARBON QUALITY AND QUANTITY AFFECT THE RETENTION AND MICROBIAL PROCESSING OF APPLIED NITROGEN

    EPA Science Inventory

    Excess nitrogen (N) from fertilizer or atmospheric deposition can have harmful effects on the environment and human health. Remediative methods of controlling N leaching and limiting other undesirable effects of excess N need to be explored if N inputs can not be reduced or bett...

  16. Performance of low-input turfgrass species as affected by mowing and nitrogen fertilization in Minnesota

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In Minnesota, most lawns and higher cut turfgrass areas consist primarily of species such as Kentucky bluegrass (Poa pratensis L.) and perennial ryegrass (Lolium perenne L.) that require significant management inputs such as frequent mowing and nitrogen fertility. Several studies have shown that oth...

  17. MINERALIZATION OF NITROGEN FROM BROILER LITTER AS AFFECTED BY SOIL TEXTURE IN THE SOUTHEASTERN COASTAL PLAIN

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A field study was conducted during 2004-2005 to determine nitrogen (N) mineralization of broiler litter (BL) in two Coastal Plain soils of differing texture, sandy or clayey. The soils were a Tifton loamy sand (fine-loamy, siliceous, thermic, Plinthic Kandiudults) and a Greenville sandy clay loam (...

  18. Rhynchophorus ferrugineus attack affects a group of compounds rather than rearranging Phoenix canariensis metabolic pathways.

    PubMed

    Giovino, Antonio; Martinelli, Federico; Saia, Sergio

    2016-04-01

    The red palm weevil (RPW; Rhynchophorus ferrugineus) is spreading worldwide and severely harming many palm species. However, most studies on RPW focused on insect biology, and little information is available about the plant response to the attack. In the present experiment, we used metabolomics to study the alteration of the leaf metabolome of Phoenix canariensis at initial (1st stage) or advanced (2nd stage) attack by RPW compared with healthy (unattacked) plants. The leaf metabolome significantly varied among treatments. At the 1st stage of attack, plants showed a reprogramming of carbohydrate and organic acid metabolism; in contrast, peptides and lipid metabolic pathways underwent more changes during the 2nd than 1st stage of attack. Enrichment metabolomics analysis indicated that RPW attack mostly affected a particular group of compounds rather than rearranging plant metabolic pathways. Some compounds selectively affected during the 1st rather than 2nd stage (e.g. phenylalanine; tryptophan; cellobiose; xylose; quinate; xylonite; idonate; and iso-threonate; cellobiotol and arbutine) are upstream events in the phenylpropanoid, terpenoid and alkaloid biosynthesis. These compounds could be designated as potential markers of initial RPW attack. However, further investigation is needed to determine efficient early screening methods of RPW attack based on the concentrations of these molecules.

  19. Epigallocatechin gallate affects glucose metabolism and increases fitness and lifespan in Drosophila melanogaster.

    PubMed

    Wagner, Anika E; Piegholdt, Stefanie; Rabe, Doerte; Baenas, Nieves; Schloesser, Anke; Eggersdorfer, Manfred; Stocker, Achim; Rimbach, Gerald

    2015-10-13

    In this study, we tested whether a standardized epigallocatechin-3-gallate (EGCG) rich green tea extract (comprising > 90% EGCG) affects fitness and lifespan as well as parameters of glucose metabolism and energy homeostasis in the fruit fly, Drosophila melanogaster. Following the application of the green tea extract a significant increase in the mean lifespan (+ 3.3 days) and the 50% survival (+ 4.3 days) as well as improved fitness was detected. These effects went along an increased expression of Spargel, the homolog of mammalian PGC1α, which has been reported to affect lifespan in flies. Intriguingly, in flies, treatment with the green tea extract decreased glucose concentrations, which were accompanied by an inhibition of α-amylase and α-glucosidase activity. Computational docking analysis proved the potential of EGCG to dock into the substrate binding pocket of α-amylase and to a greater extent into α-glucosidase. Furthermore, we demonstrate that EGCG downregulates insulin-like peptide 5 and phosphoenolpyruvate carboxykinase, major regulators of glucose metabolism, as well as the Drosophila homolog of leptin, unpaired 2. We propose that a decrease in glucose metabolism in connection with an upregulated expression of Spargel contribute to the better fitness and the extended lifespan in EGCG-treated flies.

  20. Silver nanoparticles affect glucose metabolism in hepatoma cells through production of reactive oxygen species

    PubMed Central

    Lee, Mi Jin; Lee, Seung Jun; Yun, Su Jin; Jang, Ji-Young; Kang, Hangoo; Kim, Kyongmin; Choi, In-Hong; Park, Sun

    2016-01-01

    The silver nanoparticle (AgNP) is a candidate for anticancer therapy because of its effects on cell survival and signaling. Although numerous reports are available regarding their effect on cell death, the effect of AgNPs on metabolism is not well understood. In this study, we investigated the effect of AgNPs on glucose metabolism in hepatoma cell lines. Lactate release from both HepG2 and Huh7 cells was reduced with 5 nm AgNPs as early as 1 hour after treatment, when cell death did not occur. Treatment with 5 nm AgNPs decreased glucose consumption in HepG2 cells but not in Huh7 cells. Treatment with 5 nm AgNPs reduced nuclear factor erythroid 2-like 2 expression in both cell types without affecting its activation at the early time points after AgNPs’ treatment. Increased reactive oxygen species (ROS) production was detected 1 hour after 5 nm AgNPs’ treatment, and lactate release was restored in the presence of an ROS scavenger. Our results suggest that 5 nm AgNPs affect glucose metabolism by producing ROS. PMID:26730190

  1. Epigallocatechin gallate affects glucose metabolism and increases fitness and lifespan in Drosophila melanogaster

    PubMed Central

    Wagner, Anika E.; Piegholdt, Stefanie; Rabe, Doerte; Baenas, Nieves; Schloesser, Anke; Eggersdorfer, Manfred; Stocker, Achim; Rimbach, Gerald

    2015-01-01

    In this study, we tested whether a standardized epigallocatechin-3-gallate (EGCG) rich green tea extract (comprising > 90% EGCG) affects fitness and lifespan as well as parameters of glucose metabolism and energy homeostasis in the fruit fly, Drosophila melanogaster. Following the application of the green tea extract a significant increase in the mean lifespan (+ 3.3 days) and the 50% survival (+ 4.3 days) as well as improved fitness was detected. These effects went along an increased expression of Spargel, the homolog of mammalian PGC1α, which has been reported to affect lifespan in flies. Intriguingly, in flies, treatment with the green tea extract decreased glucose concentrations, which were accompanied by an inhibition of α-amylase and α-glucosidase activity. Computational docking analysis proved the potential of EGCG to dock into the substrate binding pocket of α-amylase and to a greater extent into α-glucosidase. Furthermore, we demonstrate that EGCG downregulates insulin-like peptide 5 and phosphoenolpyruvate carboxykinase, major regulators of glucose metabolism, as well as the Drosophila homolog of leptin, unpaired 2. We propose that a decrease in glucose metabolism in connection with an upregulated expression of Spargel contribute to the better fitness and the extended lifespan in EGCG-treated flies. PMID:26375250

  2. Antimicrobial drug resistance affects broad changes in metabolomic phenotype in addition to secondary metabolism

    PubMed Central

    Derewacz, Dagmara K.; Goodwin, Cody R.; McNees, C. Ruth; McLean, John A.; Bachmann, Brian O.

    2013-01-01

    Bacteria develop resistance to many classes of antibiotics vertically, by engendering mutations in genes encoding transcriptional and translational apparatus. These severe adaptations affect global transcription, translation, and the correspondingly affected metabolism. Here, we characterize metabolome scale changes in transcriptional and translational mutants in a genomically characterized Nocardiopsis, a soil-derived actinomycete, in stationary phase. Analysis of ultra-performance liquid chromatography–ion mobility–mass spectrometry metabolomic features from a cohort of streptomycin- and rifampicin-resistant mutants grown in the absence of antibiotics exhibits clear metabolomic speciation, and loadings analysis catalogs a marked change in metabolic phenotype. Consistent with derepression, up to 311 features are observed in antibiotic-resistant mutants that are not detected in their progenitors. Mutants demonstrate changes in primary metabolism, such as modulation of fatty acid composition and the increased production of the osmoprotectant ectoine, in addition to the presence of abundant emergent potential secondary metabolites. Isolation of three of these metabolites followed by structure elucidation demonstrates them to be an unusual polyketide family with a previously uncharacterized xanthene framework resulting from sequential oxidative carbon skeletal rearrangements. Designated as “mutaxanthenes,” this family can be correlated to a type II polyketide gene cluster in the producing organism. Taken together, these data suggest that biosynthetic pathway derepression is a general consequence of some antibiotic resistance mutations. PMID:23341601

  3. Silver nanoparticles affect glucose metabolism in hepatoma cells through production of reactive oxygen species.

    PubMed

    Lee, Mi Jin; Lee, Seung Jun; Yun, Su Jin; Jang, Ji-Young; Kang, Hangoo; Kim, Kyongmin; Choi, In-Hong; Park, Sun

    2016-01-01

    The silver nanoparticle (AgNP) is a candidate for anticancer therapy because of its effects on cell survival and signaling. Although numerous reports are available regarding their effect on cell death, the effect of AgNPs on metabolism is not well understood. In this study, we investigated the effect of AgNPs on glucose metabolism in hepatoma cell lines. Lactate release from both HepG2 and Huh7 cells was reduced with 5 nm AgNPs as early as 1 hour after treatment, when cell death did not occur. Treatment with 5 nm AgNPs decreased glucose consumption in HepG2 cells but not in Huh7 cells. Treatment with 5 nm AgNPs reduced nuclear factor erythroid 2-like 2 expression in both cell types without affecting its activation at the early time points after AgNPs' treatment. Increased reactive oxygen species (ROS) production was detected 1 hour after 5 nm AgNPs' treatment, and lactate release was restored in the presence of an ROS scavenger. Our results suggest that 5 nm AgNPs affect glucose metabolism by producing ROS.

  4. An assessment of landscape characteristics affecting estuarine nitrogen loading in an urban watershed.

    PubMed

    Yang, Xiaojun

    2012-02-01

    Exploring the quantitative association between landscape characteristics and the ecological conditions of receiving waters has recently become an emerging area for eco-environmental research. While the landscape-water relationship research has largely targeted on inland aquatic systems, there has been an increasing need to develop methods and techniques that can better work with coastal and estuarine ecosystems. In this paper, we present a geospatial approach to examine the quantitative relationship between landscape characteristics and estuarine nitrogen loading in an urban watershed. The case study site is in the Pensacola estuarine drainage area, home of the city of Pensacola, Florida, USA, where vigorous urban sprawling has prompted growing concerns on the estuarine ecological health. Central to this research is a remote sensor image that has been used to extract land use/cover information and derive landscape metrics. Several significant landscape metrics are selected and spatially linked with the nitrogen loading data for the Pensacola bay area. Landscape metrics and nitrogen loading are summarized by equal overland flow-length rings, and their association is examined by using multivariate statistical analysis. And a stepwise model-building protocol is used for regression designs to help identify significant variables that can explain much of the variance in the nitrogen loading dataset. It is found that using landscape composition or spatial configuration alone can explain most of the nitrogen loading variability. Of all the regression models using metrics derived from a single land use/cover class as the independent variables, the one from the low density urban gives the highest adjusted R-square score, suggesting the impact of the watershed-wide urban sprawl upon this sensitive estuarine ecosystem. Measures towards the reduction of non-point source pollution from urban development are necessary in the area to protect the Pensacola bay ecosystem and its

  5. The master regulator PhoP coordinates phosphate and nitrogen metabolism, respiration, cell differentiation and antibiotic biosynthesis: comparison in Streptomyces coelicolor and Streptomyces avermitilis.

    PubMed

    Martín, Juan F; Rodríguez-García, Antonio; Liras, Paloma

    2017-03-15

    Phosphate limitation is important for production of antibiotics and other secondary metabolites in Streptomyces. Phosphate control is mediated by the two-component system PhoR-PhoP. Following phosphate depletion, PhoP stimulates expression of genes involved in scavenging, transport and mobilization of phosphate, and represses the utilization of nitrogen sources. PhoP reduces expression of genes for aerobic respiration and activates nitrate respiration genes. PhoP activates genes for teichuronic acid formation and reduces expression of genes for phosphate-rich teichoic acid biosynthesis. In Streptomyces coelicolor, PhoP repressed several differentiation and pleiotropic regulatory genes, which affects development and indirectly antibiotic biosynthesis. A new bioinformatics analysis of the putative PhoP-binding sequences in Streptomyces avermitilis was made. Many sequences in S. avermitilis genome showed high weight values and were classified according to the available genetic information. These genes encode phosphate scavenging proteins, phosphate transporters and nitrogen metabolism genes. Among of the genes highlighted in the new studies was aveR, located in the avermectin gene cluster, encoding a LAL-type regulator, and afsS, which is regulated by PhoP and AfsR. The sequence logo for S. avermitilis PHO boxes is similar to that of S. coelicolor, with differences in the weight value for specific nucleotides in the sequence.The Journal of Antibiotics advance online publication, 15 March 2017; doi:10.1038/ja.2017.19.

  6. Leucine-nitrogen metabolism in the brain of conscious rats: its role as a nitrogen carrier in glutamate synthesis in glial and neuronal metabolic compartments.

    PubMed

    Sakai, Ryosei; Cohen, David M; Henry, Joseph F; Burrin, Douglas G; Reeds, Peter J

    2004-02-01

    The source of nitrogen (N) for the de novo synthesis of brain glutamate, glutamine and GABA remains controversial. Because leucine is readily transported into the brain and the brain contains high activities of branched-chain aminotransferase (BCAT), we hypothesized that leucine is the predominant N-precursor for brain glutamate synthesis. Conscious and unstressed rats administered with [U-13C] and/or [15N]leucine as additions to the diet were killed at 0-9 h of continuous feeding. Plasma and brain leucine equilibrated rapidly and the brain leucine-N turnover was more than 100%/min. The isotopic dilution of [U-13C]leucine (brain/plasma ratio 0.61 +/- 0.06) and [15N]leucine (0.23 +/- 0.06) differed markedly, suggesting that 15% of cerebral leucine-N turnover derived from proteolysis and 62% from leucine synthesis via reverse transamination. The rate of glutamate synthesis from leucine was 5 micro mol/g/h and at least 50% of glutamate-N originally derived from leucine. The enrichment of [5-15N]glutamine was higher than [15N]ammonia in the brain, indicating glial ammonia generation from leucine via glutamate. The enrichment of [15N]GABA, [15N]aspartate, [15N]glutamate greater than [2-15N]glutamine suggests direct incorporation of leucine-N into both glial and neuronal glutamate. These findings provide a new insight for the role of leucine as N-carrier from the plasma pool and within the cerebral compartments.

  7. Early life antibiotic exposure affects pancreatic islet development and metabolic regulation

    PubMed Central

    Li, Jiaying; Yang, Kaiyuan; Ju, Tingting; Ho, Tracy; McKay, Catharine A.; Gao, Yanhua; Forget, Shay K.; Gartner, Stephanie R.; Field, Catherine J.; Chan, Catherine B.; Willing, Benjamin P.

    2017-01-01

    Childhood antibiotic exposure has been recently linked with increased risk of metabolic disease later in life. A better understanding of this association would potentially provide strategies to reduce the childhood chronic disease epidemic. Therefore, we explored the underlying mechanisms using a swine model that better mimics human infants than rodents, and demonstrated that early life antibiotic exposure affects glucose metabolism 5 weeks after antibiotic withdrawal, which was associated with changes in pancreatic development. Antibiotics exerted a transient impact on postnatal gut microbiota colonization and microbial metabolite production, yet changes in the expression of key genes involved in short-chain fatty acid signaling and pancreatic development were detected in later life. These findings suggest a programming effect of early life antibiotic exposure that merits further investigation. PMID:28150721

  8. Dietary electrolyte balance affects growth performance, amylase activity and metabolic response in the meagre (Argyrosomus regius).

    PubMed

    Magnoni, Leonardo J; Salas-Leiton, Emilio; Peixoto, Maria-João; Pereira, Luis; Silva-Brito, Francisca; Fontinha, Filipa; Gonçalves, José F M; Wilson, Jonathan M; Schrama, Johan W; Ozório, Rodrigo O A

    2017-03-16

    Dietary ion content is known to alter the acid-base balance in freshwater fish. The current study investigated the metabolic impact of acid-base disturbances produced by differences in dietary electrolyte balance (DEB) in the meagre (Argyrosomus regius), an euryhaline species. Changes in fish performance, gastric chyme characteristics, pH and ion concentrations in the bloodstream, digestive enzyme activities and metabolic rates were analyzed in meagre fed ad libitum two experimental diets (DEB 200 or DEB 700mEq/kg) differing in the Na2CO3 content for 69days. Fish fed the DEB 200 diet had 60-66% better growth performance than the DEB 700 group. Meagre consuming the DEB 200 diet were 90-96% more efficient than fish fed the DEB 700 diet at allocating energy from feed into somatic growth. The pH values in blood were significantly lower in the DEB 700 group 2h after feeding when compared to DEB 200, indicating that acid-base balance in meagre was affected by electrolyte balance in diet. Osmolality, and Na(+) and K(+) concentrations in plasma did not vary with the dietary treatment. Gastric chyme in the DEB 700 group had higher pH values, dry matter, protein and energy contents, but lower lipid content than in the DEB 200 group. Twenty-four hours after feeding, amylase activity was higher in the gastrointestinal tract of DEB 700 group when compared to the DEB 200 group. DEB 700 group had lower routine metabolic (RMR) and standard metabolic (SMR) rates, indicating a decrease in maintenance energy expenditure 48h after feeding the alkaline diet. The current study demonstrates that feeding meagre with an alkaline diet not only causes acid-base imbalance, but also negatively affects digestion and possibly nutrient assimilation, resulting in decreased growth performance.

  9. Relationship between potassium fertilization and nitrogen metabolism in the leaf subtending the cotton (Gossypium hirsutum L.) boll during the boll development stage.

    PubMed

    Hu, Wei; Zhao, Wenqing; Yang, Jiashuo; Oosterhuis, Derrick M; Loka, Dimitra A; Zhou, Zhiguo

    2016-04-01

    The nitrogen (N) metabolism of the leaf subtending the cotton boll (LSCB) was studied with two cotton (Gossypium hirsutum L.) cultivars (Simian 3, low-K tolerant; Siza 3, low-K sensitive) under three levels of potassium (K) fertilization (K0: 0 g K2O plant(-1), K1: 4.5 K2O plant(-1) and K2: 9.0 g K2O plant(-1)). The results showed that total dry matter increased by 13.1-27.4% and 11.2-18.5% under K supply for Simian 3 and Siza 3. Boll biomass and boll weight also increased significantly in K1 and K2 treatments. Leaf K content, leaf N content and nitrate (NO3(-)) content increased with increasing K rates, and leaf N content or NO3(-) content had a significant positive correlation with leaf K content. Free amino acid content increased in the K0 treatment for both cultivars, due to increased protein degradation caused by higher protease and peptidase activities, resulting in lower protein content in the K0 treatment. The critical leaf K content for free amino acid and soluble protein content were 14 mg g(-1) and 15 mg g(-1) in Simian 3, and 17 mg g(-1) and 18 mg g(-1) in Siza 3, respectively. Nitrate reductase (NR), glutamic-oxaloace transaminase (GOT) and glutamic-pyruvic transaminase (GPT) activities increased in the K1 and K2 treatments for both cultivars, while glutamine synthetase (GS) and glutamate synthase (GOGAT) activities increased under K supply treatments only for Siza 3, and were not affected in Simian 3, indicating that this was the primary difference in nitrogen-metabolizing enzymes activities for the two cultivars with different sensitivity to low-K.

  10. Differential Role of Glutamate Dehydrogenase in Nitrogen Metabolism of Maize Tissues 1

    PubMed Central

    Loyola-Vargas, Victor Manuel; de Jimenez, Estela Sanchez

    1984-01-01

    Both calli and plantlets of maize (Zea mays L. var Tuxpeño 1) were exposed to specific nitrogen sources, and the aminative (NADH) and deaminative (NAD+) glutamate dehydrogenase activities were measured at various periods of time in homogenates of calli, roots, and leaves. A differential effect of the nitrogen sources on the tissues tested was observed. In callus tissue, glutamate, ammonium, and urea inhibited glutamate dehydrogenase (GDH) activity. The amination and deamination reactions also showed different ratios of activity under different nitrogen sources. In roots, ammonium and glutamine produced an increase in GDH-NADH activity whereas the same metabolites were inhibitory of this activity in leaves. These data suggest the presence of isoenzymes or conformers of GDH, specific for each tissue, whose activities vary depending on the nutritional requirements of the tissue and the state of differentiation. PMID:16663876

  11. Select nutrients, progesterone, and interferon tau affect conceptus metabolism and development.

    PubMed

    Bazer, Fuller W; Kim, Jingyoung; Song, Gwonhwa; Ka, Hakhyun; Tekwe, Carmen D; Wu, Guoyao

    2012-10-01

    Interferon tau (IFNT), a novel multifunctional type I interferon secreted by trophectoderm, is the pregnancy recognition signal in ruminants that also has antiviral, antiproliferative, and immunomodulatory bioactivities. IFNT, with progesterone, affects availability of the metabolic substrate in the uterine lumen by inducing expression of genes for transport of select nutrients into the uterine lumen that activate mammalian target of rapamycin (mTOR) cell signaling responsible for proliferation, migration, and protein synthesis by conceptus trophectoderm. As an immunomodulatory protein, IFNT induces an anti-inflammatory state affecting metabolic events that decrease adiposity and glutamine:fructose-6-phosphate amidotransferase 1 activity, while increasing insulin sensitivity, nitric oxide production by endothelial cells, and brown adipose tissue in rats. This short review focuses on effects of IFNT and progesterone affecting transport of select nutrients into the uterine lumen to stimulate mTOR cell signaling required for conceptus development, as well as effects of IFNT on the immune system and adiposity in rats with respect to its potential therapeutic value in reducing obesity.

  12. Aging of myelinating glial cells predominantly affects lipid metabolism and immune response pathways.

    PubMed

    Verdier, Valérie; Csárdi, Gábor; de Preux-Charles, Anne-Sophie; Médard, Jean-Jacques; Smit, August B; Verheijen, Mark H G; Bergmann, Sven; Chrast, Roman

    2012-05-01

    Both the central and the peripheral nervous systems are prone to multiple age-dependent neurological deficits, often attributed to still unknown alterations in the function of myelinating glia. To uncover the biological processes affected in glial cells by aging, we analyzed gene expression of the Schwann cell-rich mouse sciatic nerve at 17 time points throughout life, from day of birth until senescence. By combining these data with the gene expression data of myelin mouse mutants carrying deletions of either Pmp22, SCAP, or Lpin1, we found that the majority of age-related transcripts were also affected in myelin mutants (54.4%) and were regulated during PNS development (59.5%), indicating a high level of overlap in implicated molecular pathways. The expression profiles in aging copied the direction of transcriptional changes observed in neuropathy models; however, they had the opposite direction when compared with PNS development. The most significantly altered biological processes in aging involved the inflammatory/immune response and lipid metabolism. Interestingly, both these pathways were comparably changed in the aging optic nerve, suggesting that similar biological processes are affected in aging of glia-rich parts of the central and peripheral nervous systems. Our comprehensive comparison of gene expression in three distinct biological conditions including development, aging, and myelin disease thus revealed a previously unanticipated relationship among themselves and identified lipid metabolism and inflammatory/immune response pathways as potential therapeutical targets to prevent or delay so far incurable age-related and inherited forms of neuropathies.

  13. Evidence for efficacy of drugs affecting bone metabolism in preventing hip fracture.

    PubMed Central

    Kanis, J. A.; Johnell, O.; Gullberg, B.; Allander, E.; Dilşen, G.; Gennari, C.; Lopes Vaz, A. A.; Lyritis, G. P.; Mazzuoli, G.; Miravet, L.

    1992-01-01

    OBJECTIVE--To examine the effects of taking drugs affecting bone metabolism on the risk of hip fracture in women aged over 50 years. DESIGN--Retrospective, population based, case-control study by questionnaire. SETTING--14 centres in six countries in southern Europe. SUBJECTS--2086 women with hip fracture and 3532 control women matched for age. MAIN OUTCOME MEASURES--Number of drugs affecting bone metabolism taken and length taken for. RESULTS--Women taking drugs affecting bone metabolism had a significantly decreased risk of hip fracture. After adjustment for differences in other risk factors, the relative risk of hip fractures was 0.55 (95% confidence interval 0.31 to 0.85) in women taking oestrogens, 0.75 (0.60 to 0.94) in those taking calcium, and 0.69 (0.51 to 0.92) in those taking calcitonin. The fall in risk was not significant for anabolic steroids (0.6 (0.29 to 1.22)). Neither vitamin D nor fluorides were associated with a significant decrease in the risk of hip fracture. The effect on hip fracture risk increased significantly with increasing duration of exposure (risk ratio 0.8 (0.61 to 1.05) for less than median exposure v 0.66 (0.5 to 0.88) for greater than median exposure). Drugs were equally effective in older and younger women, with the exception of oestrogen. CONCLUSIONS--Oestrogen, calcium, and calcitonins significantly decrease the risk of hip fracture. Short term intervention late in the natural course of osteoporosis may have significant effects on the incidence of hip fracture. PMID:1463947

  14. Dissimilatory nitrate reduction to ammonium conserves nitrogen in anthropogenically affected subtropical mangrove sediments in Southeast China.

    PubMed

    Cao, Wenzhi; Yang, Jingxin; Li, Ying; Liu, Baoli; Wang, Feifei; Chang, Changtang

    2016-09-15

    In this study, basic sediment properties, nutrient flux, and nitrogen cycle (including denitrification, anaerobic ammonium oxidation [anammox], nitrification, and dissimilatory nitrate reduction to ammonium [DNRA]) were investigated at two sampling sites with different tree ages in the mangrove region of the Jiulong River Estuary, China. The results show that sediments at mangrove flat area have relatively strong capability to reduce NO3(-), in which the DNRA rate is relatively high (204.53±48.32μmolNm(-2)h(-1)), which is approximately 75.7-85.9% of the total NO3(-) reduction, while the denitrification and anammox rates are relatively low - only approximately 5.6-9.5% and 8.5-14.8% of the total NO3(-) reduction, respectively. Thus, in the nitrogen-enriched subtropical mangrove system, DNRA is the main pathway to reduce NO3(-), and most of the input nitrogen is conserved as NH4(+) in the system, which assures high productivity of the mangrove system.

  15. Proteins associated with heat-induced leaf senescence in creeping bentgrass as affected by foliar application of nitrogen, cytokinins, and an ethylene inhibitor.

    PubMed

    Jespersen, David; Huang, Bingru

    2015-02-01

    Heat stress causes premature leaf senescence in cool-season grass species. The objective of this study was to identify proteins regulated by nitrogen, cytokinins, and ethylene inhibitor in relation to heat-induced leaf senescence in creeping bentgrass (Agrostis stolonifera). Plants (cv. Penncross) were foliar sprayed with 18 mM carbonyldiamide (N source), 25 μM aminoethoxyvinylglycine (AVG, ethylene inhibitor), 25 μM zeatin riboside (ZR, cytokinin), or a water control, and then exposed to 20/15°C (day/night) or 35/30°C (heat stress) in growth chambers. All treatments suppressed heat-induced leaf senescence, as shown by higher turf quality and chlorophyll content, and lower electrolyte leakage in treated plants compared to the untreated control. A total of 49 proteins were responsive to N, AVG, or ZR under heat stress. The abundance of proteins in photosynthesis increased, with ribulose-1,5-bisphosphate carboxylase/oxygenase affected by all three treatments, chlorophyll a/b-binding protein by AVG and N or Rubisco activase by AVG. Proteins for amino acid metabolism were upregulated, including alanine aminotransferase by three treatments and ferredoxin-dependent glutamate synthase by AVG and N. Upregulated proteins also included catalase by AVG and N and heat shock protein by ZR. Exogenous applications of AVG, ZR, or N downregulated proteins in respiration (enolase, glyceraldehyde 3-phosphate dehydrogenase, and succinate dehygrogenase) under heat stress. Alleviation of heat-induced senescence by N, AVG, or ZR was associated with enhanced protein abundance in photosynthesis and amino acid metabolism and stress defense systems (heat shock protection and antioxidants), as well as suppression of those imparting respiration metabolism.

  16. Metabolic pathways for lipid synthesis under nitrogen stress in Chlamydomonas and Nannochloropsis.

    PubMed

    Banerjee, Avik; Maiti, Subodh K; Guria, Chandan; Banerjee, Chiranjib

    2017-01-01

    Microalgae are currently being considered as a clean, sustainable and renewable energy source. Enzymes that catalyse the metabolic pathways for biofuel production are specific and require strict regulation and co-ordination. Thorough knowledge of these key enzymes along with their regulatory molecules is essential to enable rational metabolic engineering, to drive the metabolic flux towards the desired metabolites of importance. This paper reviews two key enzymes that play their role in production of bio-oil: DGAT (acyl-CoA:diacylglycerol acyltransferase) and PDAT (phospholipid:diacylglycerol acyltransferase). It also deals with the transcription factors that control the enzymes while cell undergoes a metabolic shift under stress. The paper also discusses the association of other enzymes and pathways that provide substrates and precursors for oil accumulation. Finally a futuristic solution has been proposed about a synthetic algal cell platform that would be committed towards biofuel synthesis.

  17. Hal4 and Hal5 protein kinases are required for general control of carbon and nitrogen uptake and metabolism.

    PubMed

    Pérez-Valle, Jorge; Rothe, Jessica; Primo, Cecilia; Martínez Pastor, Mar; Ariño, Joaquin; Pascual-Ahuir, Amparo; Mulet, José Miguel; Serrano, Ramón; Yenush, Lynne

    2010-12-01

    The yeast protein kinases Sat4/Hal4 and Hal5 are required for the plasma membrane stability of the K(+) transporter Trk1 and some amino acid and glucose permeases. The transcriptomic analysis presented here indicates alterations in the general control of the metabolism of both nitrogen and carbon. Accordingly, we observed reduced uptake of methionine and leucine in the hal4 hal5 mutant. This decrease correlates with activation of the Gcn2-Gcn4 pathway, as measured by expression of the lacZ gene under the control of the GCN4 promoter. However, with the exception of methionine biosynthetic genes, few amino acid biosynthetic genes are induced in the hal4 hal5 mutant, whereas several genes involved in amino acid catabolism are repressed. Concerning glucose metabolism, we found that this mutant exhibits derepression of respiratory genes in the presence of glucose, leading to an increased activity of mitochondrial enzymes, as measured by succinate dehydrogenase (SDH) activity. In addition, the reduced glucose consumption in the hal4 hal5 mutant correlates with a more acidic intracellular pH and with low activity of the plasma membrane H(+)-ATPase. As a compensatory mechanism for the low glycolytic rate, the hal4 hal5 mutant overexpresses the HXT4 high-affinity glucose transporter and the hexokinase genes. These results indicate that the hal4 hal5 mutant presents defects in the general control of nitrogen and carbon metabolism, which correlate with reduced transport of amino acids and glucose, respectively. A more acidic intracellular pH may contribute to some defects of this mutant.

  18. Draft Genome Sequences of Eight Obligate Methane Oxidizers Occupying Distinct Niches Based on Their Nitrogen Metabolism

    PubMed Central

    De Vos, Paul; Vekeman, Bram

    2016-01-01

    The genome sequences of Methylomonas methanica (NCIMB 11130T, R-45363, and R-45371), Methylomonas koyamae (R-45378, R-45383, and R-49807), Methylomonas lenta (R-45370), and Methylosinus sp. (R-45379) were obtained. These aerobic methanotrophs were isolated from terrestrial ecosystems, and their distinct phenotypes related to nitrogen assimilation and dissimilation were previously reported. PMID:27491982

  19. Carboxylation of osteocalcin affects its association with metabolic parameters in healthy children.

    PubMed

    Prats-Puig, Anna; Mas-Parareda, Marta; Riera-Pérez, Elena; González-Forcadell, Dolors; Mier, Concepció; Mallol-Guisset, Montserrat; Díaz, Marta; Bassols, Judit; de Zegher, Francis; Ibáñez, Lourdes; López-Bermejo, Abel

    2010-03-01

    OBJECTIVE Osteocalcin (OC), a bone-derived protein, was recently shown to regulate metabolic pathways in mice. Undercarboxylated OC (ucOC), but not carboxylated OC (cOC), increases adiponectin and insulin secretion. It is unclear if carboxylation of OC affects its association with metabolic parameters in humans. RESEARCH DESIGN AND METHODS The associations between ucOC, cOC, total and high-molecular-weight (HMW) adiponectin, and insulin secretion (homeostasis model assessment [HOMA]-beta) were investigated in a population-based sample of healthy prepubertal children (n = 103; 49 boys and 54 girls). RESULTS Weight-dependent associations were observed between the different forms of OC and metabolic parameters. Higher cOC was related to lower HMW adiponectin (with a stronger association in leaner children; P < 0.001). Higher ucOC-to-cOC ratio was associated with higher HOMA-beta (P < 0.01) in leaner children and associated with higher HMW adiponectin (P < 0.001) in heavier children. CONCLUSIONS In a weight-dependent manner, cOC and the proportion of ucOC are differentially related to HMW adiponectin and insulin secretion in healthy children.

  20. Carboxylation of Osteocalcin Affects Its Association With Metabolic Parameters in Healthy Children

    PubMed Central

    Prats-Puig, Anna; Mas-Parareda, Marta; Riera-Pérez, Elena; González-Forcadell, Dolors; Mier, Concepció; Mallol-Guisset, Montserrat; Díaz, Marta; Bassols, Judit; de Zegher, Francis; Ibáñez, Lourdes; López-Bermejo, Abel

    2010-01-01

    OBJECTIVE Osteocalcin (OC), a bone-derived protein, was recently shown to regulate metabolic pathways in mice. Undercarboxylated OC (ucOC), but not carboxylated OC (cOC), increases adiponectin and insulin secretion. It is unclear if carboxylation of OC affects its association with metabolic parameters in humans. RESEARCH DESIGN AND METHODS The associations between ucOC, cOC, total and high-molecular-weight (HMW) adiponectin, and insulin secretion (homeostasis model assessment [HOMA]-β) were investigated in a population-based sample of healthy prepubertal children (n = 103; 49 boys and 54 girls). RESULTS Weight-dependent associations were observed between the different forms of OC and metabolic parameters. Higher cOC was related to lower HMW adiponectin (with a stronger association in leaner children; P < 0.001). Higher ucOC-to-cOC ratio was associated with higher HOMA-β (P < 0.01) in leaner children and associated with higher HMW adiponectin (P < 0.001) in heavier children. CONCLUSIONS In a weight-dependent manner, cOC and the proportion of ucOC are differentially related to HMW adiponectin and insulin secretion in healthy children. PMID:20009098

  1. Cannibalism Affects Core Metabolic Processes in Helicoverpa armigera Larvae—A 2D NMR Metabolomics Study

    PubMed Central

    Vergara, Fredd; Shino, Amiu; Kikuchi, Jun

    2016-01-01

    Cannibalism is known in many insect species, yet its impact on insect metabolism has not been investigated in detail. This study assessed the effects of cannibalism on the metabolism of fourth-instar larvae of the non-predatory insect Helicoverpa armigera (Lepidotera: Noctuidea). Two groups of larvae were analyzed: one group fed with fourth-instar larvae of H. armigera (cannibal), the other group fed with an artificial plant diet. Water-soluble small organic compounds present in the larvae were analyzed using two-dimensional nuclear magnetic resonance (NMR) and principal component analysis (PCA). Cannibalism negatively affected larval growth. PCA of NMR spectra showed that the metabolic profiles of cannibal and herbivore larvae were statistically different with monomeric sugars, fatty acid- and amino acid-related metabolites as the most variable compounds. Quantitation of 1H-13C HSQC (Heteronuclear Single Quantum Coherence) signals revealed that the concentrations of glucose, glucono-1,5-lactone, glycerol phosphate, glutamine, glycine, leucine, isoleucine, lysine, ornithine, proline, threonine and valine were higher in the herbivore larvae. PMID:27598144

  2. The fungicide triadimefon affects beer flavor and composition by influencing Saccharomyces cerevisiae metabolism.

    PubMed

    Kong, Zhiqiang; Li, Minmin; An, Jingjing; Chen, Jieying; Bao, Yuming; Francis, Frédéric; Dai, Xiaofeng

    2016-09-15

    Despite the fact that beer is produced on a large scale, the effects of pesticide residues on beer have been rarely investigated. In this study, we used micro-brewing settings to determine the effect of triadimefon on the growth of Saccharomyces cerevisiae and beer flavor. The yeast growth in medium was significantly inhibited (45%) at concentrations higher than 5 mg L(-1), reaching 80% and 100% inhibition at 10 mg L(-1) and 50 mg L(-1), respectively. There were significant differences in sensory quality between beer samples fermented with and without triadimefon based on data obtained with an electronic tongue and nose. Such an effect was most likely underlain by changes in yeast fermentation activity, including decreased utilization of maltotriose and most amino acids, reduced production of isobutyl and isoamyl alcohols, and increased ethyl acetate content in the fungicide treated samples. Furthermore, yeast metabolic profiling by phenotype microarray and UPLC/TOF-MS showed that triadimefon caused significant changes in the metabolism of glutathione, phenylalanine and sphingolipids, and in sterol biosynthesis. Thus, triadimefon negatively affects beer sensory qualities by influencing the metabolic activity of S. cerevisiae during fermentation, emphasizing the necessity of stricter control over fungicide residues in brewing by the food industry.

  3. L-carnosine affects the growth of Saccharomyces cerevisiae in a metabolism-dependent manner.

    PubMed

    Cartwright, Stephanie P; Bill, Roslyn M; Hipkiss, Alan R

    2012-01-01

    The dipeptide L-carnosine (β-alanyl-L-histidine) has been described as enigmatic: it inhibits growth of cancer cells but delays senescence in cultured human fibroblasts and extends the lifespan of male fruit flies. In an attempt to understand these observations, the effects of L-carnosine on the model eukaryote, Saccharomyces cerevisiae, were examined on account of its unique metabolic properties; S. cerevisiae can respire aerobically, but like some tumor cells, it can also exhibit a metabolism in which aerobic respiration is down regulated. L-Carnosine exhibited both inhibitory and stimulatory effects on yeast cells, dependent upon the carbon source in the growth medium. When yeast cells were not reliant on oxidative phosphorylation for energy generation (e.g. when grown on a fermentable carbon source such as 2% glucose), 10-30 mM L-carnosine slowed growth rates in a dose-dependent manner and increased cell death by up to 17%. In contrast, in media containing a non-fermentable carbon source in which yeast are dependent on aerobic respiration (e.g. 2% glycerol), L-carnosine did not provoke cell death. This latter observation was confirmed in the respiratory yeast, Pichia pastoris. Moreover, when deletion strains in the yeast nutrient-sensing pathway were treated with L-carnosine, the cells showed resistance to its inhibitory effects. These findings suggest that L-carnosine affects cells in a metabolism-dependent manner and provide a rationale for its effects on different cell types.

  4. The fungicide triadimefon affects beer flavor and composition by influencing Saccharomyces cerevisiae metabolism

    NASA Astrophysics Data System (ADS)

    Kong, Zhiqiang; Li, Minmin; An, Jingjing; Chen, Jieying; Bao, Yuming; Francis, Frédéric; Dai, Xiaofeng

    2016-09-01

    Despite the fact that beer is produced on a large scale, the effects of pesticide residues on beer have been rarely investigated. In this study, we used micro-brewing settings to determine the effect of triadimefon on the growth of Saccharomyces cerevisiae and beer flavor. The yeast growth in medium was significantly inhibited (45%) at concentrations higher than 5 mg L‑1, reaching 80% and 100% inhibition at 10 mg L‑1 and 50 mg L‑1, respectively. There were significant differences in sensory quality between beer samples fermented with and without triadimefon based on data obtained with an electronic tongue and nose. Such an effect was most likely underlain by changes in yeast fermentation activity, including decreased utilization of maltotriose and most amino acids, reduced production of isobutyl and isoamyl alcohols, and increased ethyl acetate content in the fungicide treated samples. Furthermore, yeast metabolic profiling by phenotype microarray and UPLC/TOF-MS showed that triadimefon caused significant changes in the metabolism of glutathione, phenylalanine and sphingolipids, and in sterol biosynthesis. Thus, triadimefon negatively affects beer sensory qualities by influencing the metabolic activity of S. cerevisiae during fermentation, emphasizing the necessity of stricter control over fungicide residues in brewing by the food industry.

  5. Central Metabolic Responses to Ozone and Herbivory Affect Photosynthesis and Stomatal Closure1[OPEN

    PubMed Central

    Khaling, Eliezer; Lassueur, Steve

    2016-01-01

    Plants have evolved adaptive mechanisms that allow them to tolerate a continuous range of abiotic and biotic stressors. Tropospheric ozone (O3), a global anthropogenic pollutant, directly affects living organisms and ecosystems, including plant-herbivore interactions. In this study, we investigate the stress responses of Brassica nigra (wild black mustard) exposed consecutively to O3 and the specialist herbivore Pieris brassicae. Transcriptomics and metabolomics data were evaluated using multivariate, correlation, and network analyses for the O3 and herbivory responses. O3 stress symptoms resembled those of senescence and phosphate starvation, while a sequential shift from O3 to herbivory induced characteristic plant defense responses, including a decrease in central metabolism, induction of the jasmonic acid/ethylene pathways, and emission of volatiles. Omics network and pathway analyses predicted a link between glycerol and central energy metabolism that influences the osmotic stress response and stomatal closure. Further physiological measurements confirmed that while O3 stress inhibited photosynthesis and carbon assimilation, sequential herbivory counteracted the initial responses induced by O3, resulting in a phenotype similar to that observed after herbivory alone. This study clarifies the consequences of multiple stress interactions on a plant metabolic system and also illustrates how omics data can be integrated to generate new hypotheses in ecology and plant physiology. PMID:27758847

  6. The fungicide triadimefon affects beer flavor and composition by influencing Saccharomyces cerevisiae metabolism

    PubMed Central

    Kong, Zhiqiang; Li, Minmin; An, Jingjing; Chen, Jieying; Bao, Yuming; Francis, Frédéric; Dai, Xiaofeng

    2016-01-01

    Despite the fact that beer is produced on a large scale, the effects of pesticide residues on beer have been rarely investigated. In this study, we used micro-brewing settings to determine the effect of triadimefon on the growth of Saccharomyces cerevisiae and beer flavor. The yeast growth in medium was significantly inhibited (45%) at concentrations higher than 5 mg L−1, reaching 80% and 100% inhibition at 10 mg L−1 and 50 mg L−1, respectively. There were significant differences in sensory quality between beer samples fermented with and without triadimefon based on data obtained with an electronic tongue and nose. Such an effect was most likely underlain by changes in yeast fermentation activity, including decreased utilization of maltotriose and most amino acids, reduced production of isobutyl and isoamyl alcohols, and increased ethyl acetate content in the fungicide treated samples. Furthermore, yeast metabolic profiling by phenotype microarray and UPLC/TOF-MS showed that triadimefon caused significant changes in the metabolism of glutathione, phenylalanine and sphingolipids, and in sterol biosynthesis. Thus, triadimefon negatively affects beer sensory qualities by influencing the metabolic activity of S. cerevisiae during fermentation, emphasizing the necessity of stricter control over fungicide residues in brewing by the food industry. PMID:27629523

  7. Community metabolism of aquatic Closed Ecological Systems: Effects of nitrogen sources

    NASA Astrophysics Data System (ADS)

    Taub, Frieda B.

    2009-10-01

    To investigate the effect of nitrogen sources on Closed Ecological Systems (CESs), three nitrogen sources (NaNO 3, sodium nitrate; NH 4Cl, ammonium chloride; and NH 4NO 3, ammonium nitrate) were each tested in freshwater CESs consisting of a chemically defined medium, three species of green algae ( Ankistrodesmus, S cenedesmus, and Selenastrum), the grazer Daphnia magna, and associated microbes, under 12 h light/12 h dark cycles. It had been hypothesized that the development of high pH in earlier CESs was the result of nitrate utilization, and that ammonium might result in acid conditions, while ammonium nitrate might result in more moderate pH. The three nitrogen sources supported similar densities of algae (estimated by in vivo fluorescence) and similar Daphnia populations. The experiments showed that pH levels rapidly increased when grazers were absent or at low abundances irrespective of the nitrogen source. Consequently, it is hypothesized that carbon cycles, rather than nitrogen sources, are responsible for the pH dynamics. Oxygen diurnal (light:dark) cycles tended to come into balance more quickly than pH. It may be more feasible to convert O 2 data to energy units (using "oxycalorific" values) than CO 2 data since CO 2 dynamics may include other chemical reactions than just photosynthesis and respiration. The feasibility of sustaining grazer populations for at least several weeks in small, simple CESs was demonstrated, along with the ability to monitor algae-grazer dynamics, and the recording of O 2 and pH measurements.

  8. Bowman-Birk inhibitor affects pathways associated with energy metabolism in Drosophila melanogaster.

    PubMed

    Li, H-M; Sun, L; Mittapalli, O; Muir, W M; Xie, J; Wu, J; Schemerhorn, B J; Jannasch, A; Chen, J Y; Zhang, F; Adamec, J; Murdock, L L; Pittendrigh, B R

    2010-06-01

    Bowman-Birk inhibitor (BBI) is toxic when fed to certain insects, including the fruit fly, Drosophila melanogaster. Dietary BBI has been demonstrated to slow growth and increase insect mortality by inhibiting the digestive enzymes trypsin and chymotrypsin, resulting in a reduced supply of amino acids. In mammals, BBI influences cellular energy metabolism. Therefore, we tested the hypothesis that dietary BBI affects energy-associated pathways in the D. melanogaster midgut. Through microarray and metabolomic analyses, we show that dietary BBI affects energy utilization pathways in the midgut cells of D. melanogaster. In addition, ultrastructure studies indicate that microvilli are significantly shortened in BBI-fed larvae. These data provide further insights into the complex cellular response of insects to dietary protease inhibitors.

  9. The Stable Level of Glutamine synthetase 2 Plays an Important Role in Rice Growth and in Carbon-Nitrogen Metabolic Balance

    PubMed Central

    Bao, Aili; Zhao, Zhuqing; Ding, Guangda; Shi, Lei; Xu, Fangsen; Cai, Hongmei

    2015-01-01

    Glutamine synthetase 2 (GS2) is a key enzyme involved in the ammonium metabolism in plant leaves. In our previous study, we obtained GS2-cosuppressed plants, which displayed a normal growth phenotype at the seedling stage, while at the tillering stage they showed a chlorosis phenotype. In this study, to investigate the chlorosis mechanism, we systematically analyzed the plant growth, carbon-nitrogen metabolism and gene expressions between the GS2-cosuppressed rice and wild-type plants. The results revealed that the GS2-cosuppressed plants exhibited a poor plant growth phenotype and a poor nitrogen transport ability, which led to nitrogen accumulation and a decline in the carbon/nitrogen ratio in the stems. Interestingly, there was a higher concentration of soluble proteins and a lower concentration of carbohydrates in the GS2-cosuppressed plants at the seedling stage, while a contrasting result was displayed at the tillering stage. The analysis of the metabolic profile showed a significant increase of sugars and organic acids. Additionally, gene expression patterns were different in root and leaf of GS2-cosuppressed plants between the seedling and tillering stage. These results indicated the important role of a stable level of GS2 transcription during normal rice development and the importance of the carbon-nitrogen metabolic balance in rice growth. PMID:26053400

  10. The Stable Level of Glutamine synthetase 2 Plays an Important Role in Rice Growth and in Carbon-Nitrogen Metabolic Balance.

    PubMed

    Bao, Aili; Zhao, Zhuqing; Ding, Guangda; Shi, Lei; Xu, Fangsen; Cai, Hongmei

    2015-06-04

    Glutamine synthetase 2 (GS2) is a key enzyme involved in the ammonium metabolism in plant leaves. In our previous study, we obtained GS2-cosuppressed plants, which displayed a normal growth phenotype at the seedling stage, while at the tillering stage they showed a chlorosis phenotype. In this study, to investigate the chlorosis mechanism, we systematically analyzed the plant growth, carbon-nitrogen metabolism and gene expressions between the GS2-cosuppressed rice and wild-type plants. The results revealed that the GS2-cosuppressed plants exhibited a poor plant growth phenotype and a poor nitrogen transport ability, which led to nitrogen accumulation and a decline in the carbon/nitrogen ratio in the stems. Interestingly, there was a higher concentration of soluble proteins and a lower concentration of carbohydrates in the GS2-cosuppressed plants at the seedling stage, while a contrasting result was displayed at the tillering stage. The analysis of the metabolic profile showed a significant increase of sugars and organic acids. Additionally, gene expression patterns were different in root and leaf of GS2-cosuppressed plants between the seedling and tillering stage. These results indicated the important role of a stable level of GS2 transcription during normal rice development and the importance of the carbon-nitrogen metabolic balance in rice growth.

  11. Do the noncaffeine ingredients of energy drinks affect metabolic responses to heavy exercise?

    PubMed

    Pettitt, Robert W; Niemeyer, JoLynne D; Sexton, Patrick J; Lipetzky, Amanda; Murray, Steven R

    2013-07-01

    Energy drinks (EDs) such as Red Bull (RB) are marketed to enhance metabolism. Secondary ingredients of EDs (e.g., taurine) have been purported to improve time trial performance; however, little research exists on how such secondary ingredients affect aerobic metabolism during heavy exercise. The purpose of this study was to investigate the effect of the secondary ingredients of RB on aerobic metabolism during and subsequent to heavy exercise. In double-blind, counterbalanced, and crossover fashion, 8 recreationally trained individuals completed a graded exercise test to determine the gas exchange threshold (GET). Subjects returned on 2 separate occasions and ingested either a 245 ml serving of RB or a control (CTRL) drink with the equivalent caffeine before engaging in two 10-minute constant-load cycling bouts, at an intensity equivalent to GET, with 3 minutes of rest between bouts. Accumulated liters of O2 (10 minutes) were higher for the first bout (17.1 ± 3.5 L) vs. the second bout (16.7 ± 3.5 L) but did not differ between drinks. Similarly, excess postexercise oxygen consumption was higher after the initial bout (RB mean, 2.6 ± 0.85 L; CTRL mean, 2.9 ± 0.90 L) vs. the second bout (RB mean, 1.5 ± 0.85 L; CTRL mean, 1.9 ± 0.87 L) but did not differ between drinks. No differences occurred between drinks for measures of heart rate or rating of perceived exertion. These results indicate that the secondary ingredients contained in a single serving of RB do not augment aerobic metabolism during or subsequent to heavy exercise.

  12. Dietary carbohydrate and lipid source affect cholesterol metabolism of European sea bass (Dicentrarchus labrax) juveniles.

    PubMed

    Castro, Carolina; Corraze, Geneviève; Pérez-Jiménez, Amalia; Larroquet, Laurence; Cluzeaud, Marianne; Panserat, Stéphane; Oliva-Teles, Aires

    2015-10-28

    Plant feedstuffs (PF) are rich in carbohydrates, which may interact with lipid metabolism. Thus, when considering dietary replacement of fishery by-products with PF, knowledge is needed on how dietary lipid source (LS) and carbohydrates affect lipid metabolism and other metabolic pathways. For that purpose, a 73-d growth trial was performed with European sea bass juveniles (IBW 74 g) fed four diets differing in LS (fish oil (FO) or a blend of vegetable oils (VO)) and carbohydrate content (0 % (CH-) or 20 % (CH+) gelatinised starch). At the end of the trial no differences among diets were observed on growth and feed utilisation. Protein efficiency ratio was, however, higher in the CH+ groups. Muscle and liver fatty acid profiles reflected the dietary LS. Dietary carbohydrate promoted higher plasma cholesterol and phospholipids (PL), whole-body and hepatic (mainly 16 : 0) lipids and increased muscular and hepatic glycogen. Except for PL, which were higher in the FO groups, no major alterations between FO and VO groups were observed on plasma metabolites (glucose, TAG, cholesterol, PL), liver and muscle glycogen, and lipid and cholesterol contents. Activities of glucose-6-phosphate dehydrogenase and malic enzyme - lipogenesis-related enzymes - increased with carbohydrate intake. Hepatic expression of genes involved in cholesterol metabolism was up-regulated with carbohydrate (HMGCR and CYP3A27) and VO (HMGCR and CYP51A1) intake. No dietary regulation of long-chain PUFA biosynthesis at the transcriptional level was observed. Overall, very few interactions between dietary carbohydrates and LS were observed. However, important insights on the direct relation between dietary carbohydrate and the cholesterol biosynthetic pathway in European sea bass were demonstrated.

  13. Oxygen Affects Gut Bacterial Colonization and Metabolic Activities in a Gnotobiotic Cockroach Model

    PubMed Central

    Tegtmeier, Dorothee; Thompson, Claire L.; Schauer, Christine

    2015-01-01

    The gut microbiota of termites and cockroaches represents complex metabolic networks of many diverse microbial populations. The distinct microenvironmental conditions within the gut and possible interactions among the microorganisms make it essential to investigate how far the metabolic properties of pure cultures reflect their activities in their natural environment. We established the cockroach Shelfordella lateralis as a gnotobiotic model and inoculated germfree nymphs with two bacterial strains isolated from the guts of conventional cockroaches. Fluorescence microscopy revealed that both strains specifically colonized the germfree hindgut. In diassociated cockroaches, the facultatively anaerobic strain EbSL (a new species of Enterobacteriaceae) always outnumbered the obligately anaerobic strain FuSL (a close relative of Fusobacterium varium), irrespective of the sequence of inoculation, which showed that precolonization by facultatively anaerobic bacteria does not necessarily favor colonization by obligate anaerobes. Comparison of the fermentation products of the cultures formed in vitro with those accumulated in situ indicated that the gut environment strongly affected the metabolic activities of both strains. The pure cultures formed the typical products of mixed-acid or butyrate fermentation, whereas the guts of gnotobiotic cockroaches accumulated mostly lactate and acetate. Similar shifts toward more-oxidized products were observed when the pure cultures were exposed to oxygen, which corroborated the strong effects of oxygen on the metabolic fluxes previously observed in termite guts. Oxygen microsensor profiles of the guts of germfree, gnotobiotic, and conventional cockroaches indicated that both gut tissue and microbiota contribute to oxygen consumption and suggest that the oxygen status influences the colonization success. PMID:26637604

  14. Oxygen Affects Gut Bacterial Colonization and Metabolic Activities in a Gnotobiotic Cockroach Model.

    PubMed

    Tegtmeier, Dorothee; Thompson, Claire L; Schauer, Christine; Brune, Andreas

    2015-12-04

    The gut microbiota of termites and cockroaches represents complex metabolic networks of many diverse microbial populations. The distinct microenvironmental conditions within the gut and possible interactions among the microorganisms make it essential to investigate how far the metabolic properties of pure cultures reflect their activities in their natural environment. We established the cockroach Shelfordella lateralis as a gnotobiotic model and inoculated germfree nymphs with two bacterial strains isolated from the guts of conventional cockroaches. Fluorescence microscopy revealed that both strains specifically colonized the germfree hindgut. In diassociated cockroaches, the facultatively anaerobic strain EbSL (a new species of Enterobacteriaceae) always outnumbered the obligately anaerobic strain FuSL (a close relative of Fusobacterium varium), irrespective of the sequence of inoculation, which showed that precolonization by facultatively anaerobic bacteria does not necessarily favor colonization by obligate anaerobes. Comparison of the fermentation products of the cultures formed in vitro with those accumulated in situ indicated that the gut environment strongly affected the metabolic activities of both strains. The pure cultures formed the typical products of mixed-acid or butyrate fermentation, whereas the guts of gnotobiotic cockroaches accumulated mostly lactate and acetate. Similar shifts toward more-oxidized products were observed when the pure cultures were exposed to oxygen, which corroborated the strong effects of oxygen on the metabolic fluxes previously observed in termite guts. Oxygen microsensor profiles of the guts of germfree, gnotobiotic, and conventional cockroaches indicated that both gut tissue and microbiota contribute to oxygen consumption and suggest that the oxygen status influences the colonization success.

  15. Cold Stress and Nitrogen Deficiency Affected Protein Expression of Psychrotrophic Dyadobacter psychrophilus B2 and Pseudomonas jessenii MP1.

    PubMed

    Suyal, Deep C; Kumar, Saurabh; Yadav, Amit; Shouche, Yogesh; Goel, Reeta

    2017-01-01

    Nitrogen (N) deficiency and low temperature conditions are the prominent facet of Western Himalayan agro-ecosystems. A slight change in the environment alters the protein expression of the microorganisms. Therefore, proteomes of the two psychrotrophs Dyadobacter psychrophilus B2 and Pseudomonas jessenii MP1 were analyzed using two dimensional electrophoresis and MALDI-TOF-MS, to determine the physiological response of altitudinally different but indigenous microorganisms in response to cold stress under N depleting conditions. Functional assessment of 150 differentially expressed proteins from both the psychrotrophs revealed several mechanisms might be involved in cold stress adaptation, protein synthesis/modifications, energy metabolism, cell growth/maintenance, etc. In both the proteomes, abundance of the proteins related to energy production and stress were significantly increased while, proteins related to biosynthesis and energy consuming processes decreased. ATP synthase subunit alpha, beta, ATP-dependent Clp protease, Enolase, groL HtpG and N(2)-fixation sustaining protein CowN proteins were found to be expressed in both B2 and MP1, similarly to previously studied diazotrophs under low temperature N2 fixing conditions and therefore, can be considered as a biomarker for monitoring the nitrogen fixation in cold niches. Nevertheless, in both the diazotrophs, a good fraction of the proteins were related to hypothetical proteins which are still uncharacterized, thereby, suggesting the need for in-depth studies on cold adapted diazotrophs and their adaptive mechanisms.

  16. Cold Stress and Nitrogen Deficiency Affected Protein Expression of Psychrotrophic Dyadobacter psychrophilus B2 and Pseudomonas jessenii MP1

    PubMed Central

    Suyal, Deep C.; Kumar, Saurabh; Yadav, Amit; Shouche, Yogesh; Goel, Reeta

    2017-01-01

    Nitrogen (N) deficiency and low temperature conditions are the prominent facet of Western Himalayan agro-ecosystems. A slight change in the environment alters the protein expression of the microorganisms. Therefore, proteomes of the two psychrotrophs Dyadobacter psychrophilus B2 and Pseudomonas jessenii MP1 were analyzed using two dimensional electrophoresis and MALDI–TOF–MS, to determine the physiological response of altitudinally different but indigenous microorganisms in response to cold stress under N depleting conditions. Functional assessment of 150 differentially expressed proteins from both the psychrotrophs revealed several mechanisms might be involved in cold stress adaptation, protein synthesis/modifications, energy metabolism, cell growth/maintenance, etc. In both the proteomes, abundance of the proteins related to energy production and stress were significantly increased while, proteins related to biosynthesis and energy consuming processes decreased. ATP synthase subunit alpha, beta, ATP-dependent Clp protease, Enolase, groL HtpG and N(2)-fixation sustaining protein CowN proteins were found to be expressed in both B2 and MP1, similarly to previously studied diazotrophs under low temperature N2 fixing conditions and therefore, can be considered as a biomarker for monitoring the nitrogen fixation in cold niches. Nevertheless, in both the diazotrophs, a good fraction of the proteins were related to hypothetical proteins which are still uncharacterized, thereby, suggesting the need for in-depth studies on cold adapted diazotrophs and their adaptive mechanisms. PMID:28352263

  17. Overexpression of the CC-type glutaredoxin, OsGRX6 affects hormone and nitrogen status in rice plants

    PubMed Central

    El-Kereamy, Ashraf; Bi, Yong-Mei; Mahmood, Kashif; Ranathunge, Kosala; Yaish, Mahmoud W.; Nambara, Eiji; Rothstein, Steven J.

    2015-01-01

    Glutaredoxins (GRXs) are small glutathione dependent oxidoreductases that belong to the Thioredoxin (TRX) superfamily and catalyze the reduction of disulfide bonds of their substrate proteins. Plant GRXs include three different groups based on the motif sequence, namely CPYC, CGFS, and CC-type proteins. The rice CC-type proteins, OsGRX6 was identified during the screening for genes whose expression changes depending on the level of available nitrate. Overexpression of OsGRX6 in rice displayed a semi-dwarf phenotype. The OsGRX6 overexpressors contain a higher nitrogen content than the wild type, indicating that OsGRX6 plays a role in homeostatic regulation of nitrogen use. Consistent with this, OsGRX6 overexpressors displayed delayed chlorophyll degradation and senescence compared to the wild type plants. To examine if the growth defect of these transgenic lines attribute to disturbed plant hormone actions, plant hormone levels were measured. The levels of two cytokinins (CKs), 2-isopentenyladenine and trans-zeatin, and gibberellin A1 (GA1) were increased in these lines. We also found that these transgenic lines were less sensitive to exogenously applied GA, suggesting that the increase in GA1 is a result of the feedback regulation. These data suggest that OsGRX6 affects hormone signaling and nitrogen status in rice plants. PMID:26579177

  18. Integrated Metabolomics, Transcriptomics and Proteomics Identifies Metabolic Pathways Affected by Anaplasma phagocytophilum Infection in Tick Cells*

    PubMed Central

    Villar, Margarita; Ayllón, Nieves; Alberdi, Pilar; Moreno, Andrés; Moreno, María; Tobes, Raquel; Mateos-Hernández, Lourdes; Weisheit, Sabine; Bell-Sakyi, Lesley; de la Fuente, José

    2015-01-01

    Anaplasma phagocytophilum is an emerging zoonotic pathogen that causes human granulocytic anaplasmosis. These intracellular bacteria establish infection by affecting cell function in both the vertebrate host and the tick vector, Ixodes scapularis. Previous studies have characterized the tick transcriptome and proteome in response to A. phagocytophilum infection. However, in the postgenomic era, the integration of omics datasets through a systems biology approach allows network-based analyses to describe the complexity and functionality of biological systems such as host–pathogen interactions and the discovery of new targets for prevention and control of infectious diseases. This study reports the first systems biology integration of metabolomics, transcriptomics, and proteomics data to characterize essential metabolic pathways involved in the tick response to A. phagocytophilum infection. The ISE6 tick cells used in this study constitute a model for hemocytes involved in pathogen infection and immune response. The results showed that infection affected protein processing in endoplasmic reticulum and glucose metabolic pathways in tick cells. These results supported tick–Anaplasma co-evolution by providing new evidence of how tick cells limit pathogen infection, while the pathogen benefits from the tick cell response to establish infection. Additionally, ticks benefit from A. phagocytophilum infection by increasing survival while pathogens guarantee transmission. The results suggested that A. phagocytophilum induces protein misfolding to limit the tick cell response and facilitate infection but requires protein degradation to prevent ER stress and cell apoptosis to survive in infected cells. Additionally, A. phagocytophilum may benefit from the tick cell's ability to limit bacterial infection through PEPCK inhibition leading to decreased glucose metabolism, which also results in the inhibition of cell apoptosis that increases infection of tick cells. These

  19. Integrated Metabolomics, Transcriptomics and Proteomics Identifies Metabolic Pathways Affected by Anaplasma phagocytophilum Infection in Tick Cells.

    PubMed

    Villar, Margarita; Ayllón, Nieves; Alberdi, Pilar; Moreno, Andrés; Moreno, María; Tobes, Raquel; Mateos-Hernández, Lourdes; Weisheit, Sabine; Bell-Sakyi, Lesley; de la Fuente, José

    2015-12-01

    Anaplasma phagocytophilum is an emerging zoonotic pathogen that causes human granulocytic anaplasmosis. These intracellular bacteria establish infection by affecting cell function in both the vertebrate host and the tick vector, Ixodes scapularis. Previous studies have characterized the tick transcriptome and proteome in response to A. phagocytophilum infection. However, in the postgenomic era, the integration of omics datasets through a systems biology approach allows network-based analyses to describe the complexity and functionality of biological systems such as host-pathogen interactions and the discovery of new targets for prevention and control of infectious diseases. This study reports the first systems biology integration of metabolomics, transcriptomics, and proteomics data to characterize essential metabolic pathways involved in the tick response to A. phagocytophilum infection. The ISE6 tick cells used in this study constitute a model for hemocytes involved in pathogen infection and immune response. The results showed that infection affected protein processing in endoplasmic reticulum and glucose metabolic pathways in tick cells. These results supported tick-Anaplasma co-evolution by providing new evidence of how tick cells limit pathogen infection, while the pathogen benefits from the tick cell response to establish infection. Additionally, ticks benefit from A. phagocytophilum infection by increasing survival while pathogens guarantee transmission. The results suggested that A. phagocytophilum induces protein misfolding to limit the tick cell response and facilitate infection but requires protein degradation to prevent ER stress and cell apoptosis to survive in infected cells. Additionally, A. phagocytophilum may benefit from the tick cell's ability to limit bacterial infection through PEPCK inhibition leading to decreased glucose metabolism, which also results in the inhibition of cell apoptosis that increases infection of tick cells. These results

  20. Macroalgae δ15N values in well-mixed estuaries: Indicator of anthropogenic nitrogen input or macroalgae metabolism?

    NASA Astrophysics Data System (ADS)

    Raimonet, Mélanie; Guillou, Gaël; Mornet, Françoise; Richard, Pierre

    2013-03-01

    Although nitrogen stable isotope ratio (δ15N) in macroalgae is widely used as a bioindicator of anthropogenic nitrogen inputs to the coastal zone, recent studies suggest the possible role of macroalgae metabolism in δ15N variability. Simultaneous determinations of δ15N of dissolved inorganic nitrogen (DIN) along the land-sea continuum, inter-species variability of δ15N and its sensitivity to environmental factors are necessary to confirm the efficiency of macroalgae δ15N in monitoring nitrogen origin in mixed-use watersheds. In this study, δ15N of annual and perennial macroalgae (Ulva sp., Enteromorpha sp., Fucus vesiculosus and Fucus serratus) are compared to δ15N-DIN along the Charente Estuary, after characterizing δ15N of the three main DIN sources (i.e. cultivated area, pasture, sewage treatment plant outlet). During late winter and spring, when human activities produce high DIN inputs, DIN sources exhibit distinct δ15N signals in nitrate (NO) and ammonium (NH): cultivated area (+6.5 ± 0.6‰ and +9.0 ± 11.0‰), pasture (+9.2 ± 1.8‰ and +12.4‰) and sewage treatment plant discharge (+16.9 ± 8.7‰ and +25.4 ± 5.9‰). While sources show distinct δN- in this multiple source catchment, the overall mixture of NO sources - generally >95% DIN - leads to low variations of δN-NO at the mouth of the estuary (+7.7 to +8.4‰). Even if estuarine δN-NO values are not significantly different from pristine continental and oceanic site (+7.3‰ and +7.4‰), macroalgae δ15N values are generally higher at the mouth of the estuary. This highlights high anthropogenic DIN inputs in the estuary, and enhanced contribution of 15N-depleted NH in oceanic waters. Although seasonal variations in δN-NO are low, the same temporal trends in macroalgae δ15N values at estuarine and oceanic sites, and inter-species differences in δ15N values, suggest that macroalgae δ15N values might be modified by the metabolic response of macroalgae to environmental parameters (e

  1. Irradiance heterogeneity within crown affects photosynthetic capacity and nitrogen distribution of leaves in Cedrela sinensis.

    PubMed

    Yoshimura, Kenichi

    2010-05-01

    Because light conditions in the forest understory are highly heterogeneous, photosynthetic acclimation to spatially variable irradiance within a crown is important for crown-level carbon assimilation. The effect of variation in irradiance within the crown on leaf nitrogen content and photosynthetic rate was examined for pinnate compound leaves in saplings of Cedrela sinensis, a pioneer deciduous tree. Five shading treatments, in which 0, 25, 50, 75 and 100% of leaves were shaded, were established by artificial heavy shading using shade screen umbrellas with 25% transmittance. Although the nitrogen content of leaves was constant regardless of shading treatment, ribulose 1.5-bisphosphate carboxylase/oxygenase (Rubisco) content and light-saturated photosynthetic capacity were lower in shade leaves within partially shaded crowns than within fully shaded crowns. Shade leaves within partially shaded crowns contained higher amount of amino acids. Most shade leaves died in partially shaded crowns, whereas more than half of shade leaves survived in totally shaded crowns. Assumptions on photosynthetic acclimation to local light conditions cannot explain why shade leaves have different photosynthetic capacities and survival rates in between partially and totally shaded crowns. Irradiance heterogeneity within the crown causes a distinct variation in photosynthetic activity between sun and shaded leaves within the crown.

  2. Role of NAD-linked glutamate dehydrogenase in nitrogen metabolism in Saccharomyces cerevisiae.

    PubMed Central

    Miller, S M; Magasanik, B

    1990-01-01

    We cloned GDH2, the gene that encodes the NAD-linked glutamate dehydrogenase in the yeast Saccharomyces cerevisiae, by purifying the enzyme, making polyclonal antibodies to it, and using the antibodies to screen a lambda gt11 yeast genomic library. A yeast strain with a deletion-disruption allele of GDH2 which replaced the wild-type gene grew very poorly with glutamate as a nitrogen source, but growth improved significantly when the strain was also provided with adenine or other nitrogenous compounds whose biosynthesis requires glutamine. Our results indicate that the NAD-linked glutamate dehydrogenase catalyzes the major, but not sole, pathway for generation of ammonia from glutamate. We also isolated yeast mutants that lacked glutamate synthase activity and present evidence which shows that normally NAD-linked glutamate dehydrogenase is not involved in glutamate biosynthesis, but that if the enzyme is overexpressed, it may function reversibly in intact cells. PMID:1975578

  3. Excessive nitrogen application dampens antioxidant capacity and grain filling in wheat as revealed by metabolic and physiological analyses

    PubMed Central

    Kong, Lingan; Xie, Yan; Hu, Ling; Si, Jisheng; Wang, Zongshuai

    2017-01-01

    In this study, field-grown wheat (Triticum aestivum L.) was treated with normal (Nn) and excessive (Ne) levels of fertilizer N. Results showed that Ne depressed the activity of superoxide dismutase and peroxidase and increased the accumulation of reactive oxygen species (ROS) and malondialdehyde. The normalized difference vegetation index (NDVI) was higher under Ne at anthesis and medium milk but similar at the early dough stage and significantly lower at the hard dough stage than that under Nn. The metabolomics analysis of the leaf responses to Ne during grain filling showed 99 metabolites that were different between Ne and Nn treatments, including phenolic and flavonoid compounds, amino acids, organic acids and lipids, which are primarily involved in ROS scavenging, N metabolism, heat stress adaptation and disease resistance. Organic carbon (C) and total N contents were affected by the Ne treatment, with lower C/N ratios developing after medium milk. Ultimately, grain yields decreased with Ne. Based on these data, compared with the normal N fertilizer treatment, we concluded that excessive N application decreased the ability to scavenge ROS, increased lipid peroxidation and caused significant metabolic changes disturbing N metabolism, secondary metabolism and lipid metabolism, which led to reduced grain filling in wheat. PMID:28233811

  4. Nitrogen-metabolism related genes in barley - haplotype diversity, linkage mapping and associations with malting and kernel quality parameters

    PubMed Central

    2013-01-01

    Background Several studies report about intra-specific trait variation of nitrogen-metabolism related traits, such as N(itrogen)-use efficiency, protein content, N-storage and remobilization in barley and related grass species. The goal of this study was to assess the intra-specific genetic diversity present in primary N-metabolism genes of barley and to investigate the associations of the detected haplotype diversity with malting and kernel quality related traits. Results Partial sequences of five genes related to N-metabolism in barley (Hordeum vulgare L.) were obtained, i.e. nitrate reductase 1, glutamine synthetase 2, ferredoxin-dependent glutamate synthase, aspartate aminotransferase and asparaginase. Two to five haplotypes in each gene were discovered in a set of 190 various varieties. The development of 33 SNP markers allowed the genotyping of all these barley varieties consisting of spring and winter types. Furthermore, these markers could be mapped in several doubled haploid populations. Cluster analysis based on haplotypes revealed a more uniform pattern of the spring barleys as compared to the winter barleys. Based on linear model approaches associations to several malting and kernel quality traits including soluble N and protein were identified. Conclusions A study was conducted to investigate the presence of sequence variation of several genes related to the primary N-metabolism in barley. The detected diversity could be related to particular phenotypic traits. Specific differences between spring and winter barleys most likely reflect different breeding aims. The developed markers can be used as tool for further genetic studies and marker-assisted selection during breeding of barley. PMID:24007272

  5. Arginine supplementation does not alter nitrogen metabolism of beef steers during a lipopolysaccharide challenge

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Demand for Arg is reported to increase during immune challenge. This study evaluated the effects of lipopolysaccharide (LPS) and abomasal Arg infusion on N metabolism and immune response of 20 ruminally cannulated steers (369 ± 46 kg BW) in a randomized block design. Each block was 20 d and consiste...

  6. Effects of arsenic on nitrogen metabolism in arsenic hyperaccumulator and non-hyperaccumulator ferns

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study investigated the effects of arsenic on the in vitro activities of the enzymes (nitrate reductase and nitrite reductase) involved in nitrate metabolism in the roots, rhizomes, and fronds of two four-month old fern plants, Pteris vittata, an arsenic-hyperaccumulator, and Pteris ensiformis, ...

  7. Quantifying Ruminal Nitrogen Metabolism Using the Omasal Sampling Technique in Cattle--A Meta-Analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mixed model analysis of data from 32 studies (122 diets) was used to validate omasal sampling for quantifying ruminal-N metabolism and to assess the relationships between nonammonia-N flow at the omasal canal and milk protein yield. Data were derived from experiments in cattle fed North American die...

  8. Influence of solar UV radiation on the nitrogen metabolism in needles of Scots pine (Pinus sylvestris L.).

    PubMed

    Krywult, Marek; Smykla, Jerzy; Kinnunen, Heli; Martz, Françoise; Sutinen, Marja-Liisa; Lakkala, Kaisa; Turunen, Minna

    2008-12-01

    Needles of 20-year-old Scots pine (Pinus sylvestris L.) saplings were studied in an ultraviolet (UV) exclusion field experiment (from 2000 to 2002) in northern Finland (67 degrees N). The chambers held filters that excluded both UV-B and UV-A, excluded UV-B only, transmitted all UV (control), or lacked filters (ambient). UV-B/UV-A exclusion decreased nitrate reductase (NR) activity of 1-year-old needles of Scots pines compared to the controls. The proportion of free amino acids varied in the range 1.08-1.94% of total proteins, and was significantly higher in needles of saplings grown under UV-B/UV-A exclusion compared to the controls or UV-B exclusion. NR activity correlated with air temperature, indicating a "chamber effect". The study showed that both UV irradiance and increasing temperature are significant modulators of nitrogen (N) metabolism in Scots pine needles.

  9. Small genetic differences between ericoid mycorrhizal fungi affect nitrogen uptake by Vaccinium.

    PubMed

    Grelet, Gwen-Aëlle; Meharg, Andrew A; Duff, Elizabeth I; Anderson, Ian C; Alexander, Ian J

    2009-01-01

    Ericoid mycorrhizal fungi have been shown to differ in their pattern of nitrogen (N) use in pure culture. Here, we investigate whether this functional variation is maintained in symbiosis using three ascomycetes from a clade not previously shown to include ericoid mycorrhizal taxa. Vaccinium macrocarpon and Vaccinium vitis-idaea were inoculated with three fungal strains known to form coils in Vaccinium roots, which differed in their patterns of N use in liquid culture. (15)N was used to trace the uptake of -N, -N and glutamine-N into shoots. (15)N transfer differed among the three fungal strains, including two that had identical internal transcribed spacer (ITS) sequences, and was quantitatively related to fungal growth in liquid culture at low carbon availability. These results demonstrate that functional differences among closely related ericoid mycorrhizal fungi are maintained in symbiosis with their hosts, and suggest that N transfer to plant shoots in ericoid mycorrhizas is under fungal control.

  10. Soil Fauna Affects Dissolved Carbon and Nitrogen in Foliar Litter in Alpine Forest and Alpine Meadow.

    PubMed

    Liao, Shu; Yang, Wanqin; Tan, Yu; Peng, Yan; Li, Jun; Tan, Bo; Wu, Fuzhong

    2015-01-01

    Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) are generally considered important active biogeochemical pools of total carbon and nitrogen. Many studies have documented the contributions of soil fauna to litter decomposition, but the effects of the soil fauna on labile substances (i.e., DOC and TDN) in litter during early decomposition are not completely clear. Therefore, a field litterbag experiment was carried out from 13th November 2013 to 23rd October 2014 in an alpine forest and an alpine meadow located on the eastern Tibetan Plateau. Litterbags with different mesh sizes were used to provide access to or prohibit the access of the soil fauna, and the concentrations of DOC and TDN in the foliar litter were measured during the winter (the onset of freezing, deep freezing and thawing stage) and the growing season (early and late). After one year of field incubation, the concentration of DOC in the litter significantly decreased, whereas the TDN concentration in the litter increased. Similar dynamic patterns were detected under the effects of the soil fauna on both DOC and TDN in the litter between the alpine forest and the alpine meadow. The soil fauna showed greater positive effects on decreasing DOC concentration in the litter in the winter than in the growing season. In contrast, the dynamics of TND in the litter were related to seasonal changes in environmental factors, rather than the soil fauna. In addition, the soil fauna promoted a decrease in litter DOC/TDN ratio in both the alpine forest and the alpine meadow throughout the first year of decomposition, except for in the late growing season. These results suggest that the soil fauna can promote decreases in DOC and TDN concentrations in litter, contributing to early litter decomposition in these cold biomes.

  11. Soil Fauna Affects Dissolved Carbon and Nitrogen in Foliar Litter in Alpine Forest and Alpine Meadow

    PubMed Central

    Liao, Shu; Yang, Wanqin; Tan, Yu; Peng, Yan; Li, Jun; Tan, Bo; Wu, Fuzhong

    2015-01-01

    Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) are generally considered important active biogeochemical pools of total carbon and nitrogen. Many studies have documented the contributions of soil fauna to litter decomposition, but the effects of the soil fauna on labile substances (i.e., DOC and TDN) in litter during early decomposition are not completely clear. Therefore, a field litterbag experiment was carried out from 13th November 2013 to 23rd October 2014 in an alpine forest and an alpine meadow located on the eastern Tibetan Plateau. Litterbags with different mesh sizes were used to provide access to or prohibit the access of the soil fauna, and the concentrations of DOC and TDN in the foliar litter were measured during the winter (the onset of freezing, deep freezing and thawing stage) and the growing season (early and late). After one year of field incubation, the concentration of DOC in the litter significantly decreased, whereas the TDN concentration in the litter increased. Similar dynamic patterns were detected under the effects of the soil fauna on both DOC and TDN in the litter between the alpine forest and the alpine meadow. The soil fauna showed greater positive effects on decreasing DOC concentration in the litter in the winter than in the growing season. In contrast, the dynamics of TND in the litter were related to seasonal changes in environmental factors, rather than the soil fauna. In addition, the soil fauna promoted a decrease in litter DOC/TDN ratio in both the alpine forest and the alpine meadow throughout the first year of decomposition, except for in the late growing season. These results suggest that the soil fauna can promote decreases in DOC and TDN concentrations in litter, contributing to early litter decomposition in these cold biomes. PMID:26406249

  12. [Effect of the active nitrogen and oxygen metabolities on the level of cGMP in uterus myocytes].

    PubMed

    Danylovych, Iu V; Tuhaĭ, V A

    2006-01-01

    The level of cGMP in myocytes of uterus of rats at an action active metabolities of nitrogen and oxygen (NO, NO2- and H2O2) in the conditions of influence of progesteron on myocytes was studied. Cell suspension was selected with the use of collagenase and soy-bean inhibitor of tripsin. Determining the amount of cGMP was conducted with the use of standard kit produced by "Amersham" (Great Britain). The basal level of cGMP in unactivated myocytes made 1.5 +/- 0.17 pmol cGMP/mg of protein (n = 5). It is shown that incubation of myocytes with 0.1 mM acetylcholin during 1 hour resulted in 2 times growth of cGMP content in suspension approximately, this increase is fully supressed in the presenced 0.1 mM methilene blue, that specifies activity of soluble cGMP in myocytes. Treatment of cells with 10 nM progesteron during 1 hour did not cause substantial changes in the level of cGMP. At the same time addition of 0.1 mM sodium nitroprussid or 10 nM H2O2 to suspension resulted in such conditions in the increase of level of cGMP to 3.1 +/- 0.6 and 6.8 +/- 0.4 pmol cGMP/mg of protein. Poor penetration of NO2- (10 nM) to the cells did not cause changes in the level of cGMP. The results got by us testify that the long-term influence of active metabolities of nitrogen and oxygen, instead of progesteron, provides the increase of the level of cGMP in the myometrium.

  13. Metabolic Regulation of “Ca. Methylacidiphilum Fumariolicum” SolV Cells Grown Under Different Nitrogen and Oxygen Limitations

    PubMed Central

    Khadem, Ahmad F.; Pol, Arjan; Wieczorek, Adam S.; Jetten, Mike S. M.; Op den Camp, Huub J. M.

    2012-01-01

    Aerobic methanotrophic bacteria can use methane as their sole energy source. The discovery of “Ca. Methylacidiphilum fumariolicum” strain SolV and other verrucomicrobial methanotrophs has revealed that the ability of bacteria to oxidize CH4 is much more diverse than has previously been assumed in terms of ecology, phylogeny, and physiology. A remarkable characteristic of the methane-oxidizing Verrucomicrobia is their extremely acidophilic phenotype, growing even below pH 1. In this study we used RNA-Seq to analyze the metabolic regulation of “Ca. M. fumariolicum” SolV cells growing at μmax in batch culture or under nitrogen fixing or oxygen limited conditions in chemostats, all at pH 2. The analysis showed that two of the three pmoCAB operons each encoding particulate methane monoxygenases were differentially expressed, probably regulated by the available oxygen. The hydrogen produced during N2 fixation is apparently recycled as demonstrated by the upregulation of the genes encoding a Ni/Fe-dependent hydrogenase. These hydrogenase genes were also upregulated under low oxygen conditions. Handling of nitrosative stress was shown by the expression of the nitric oxide reductase encoding genes norB and norC under all conditions tested, the upregulation of nitrite reductase nirK under oxygen limitation and of hydroxylamine oxidoreductase hao in the presence of ammonium. Unraveling the gene regulation of carbon and nitrogen metabolism helps to understand the underlying physiological adaptations of strain SolV in view of the harsh conditions of its natural ecosystem. PMID:22848206

  14. Metabolic Impacts of Using Nitrogen and Copper-Regulated Promoters to Regulate Gene Expression in Neurospora crassa.

    PubMed

    Ouyang, Shouqiang; Beecher, Consuelo N; Wang, Kang; Larive, Cynthia K; Borkovich, Katherine A

    2015-07-20

    The filamentous fungus Neurospora crassa is a long-studied eukaryotic microbial system amenable to heterologous expression of native and foreign proteins. However, relatively few highly tunable promoters have been developed for this species. In this study, we compare the tcu-1 and nit-6 promoters for controlled expression of a GFP reporter gene in N. crassa. Although the copper-regulated tcu-1 has been previously characterized, this is the first investigation exploring nitrogen-controlled nit-6 for expression of heterologous genes in N. crassa. We determined that fragments corresponding to 1.5-kb fragments upstream of the tcu-1 and nit-6 open reading frames are needed for optimal repression and expression of GFP mRNA and protein. nit-6 was repressed using concentrations of glutamine from 2 to 20 mM and induced in medium containing 0.5-20 mM nitrate as the nitrogen source. Highest levels of expression were achieved within 3 hr of induction for each promoter and GFP mRNA could not be detected within 1 hr after transfer to repressing conditions using the nit-6 promoter. We also performed metabolic profiling experiments using proton NMR to identify changes in metabolite levels under inducing and repressing conditions for each promoter. The results demonstrate that conditions used to regulate tcu-1 do not significantly change the primary metabolome and that the differences between inducing and repressing conditions for nit-6 can be accounted for by growth under nitrate or glutamine as a nitrogen source. Our findings demonstrate that nit-6 is a tunable promoter that joins tcu-1 as a choice for regulation of gene expression in N. crassa.

  15. A consortium of non-rhizobial endophytic microbes from Typha angustifolia functions as probiotic in rice and improves nitrogen metabolism.

    PubMed

    Saha, C; Mukherjee, G; Agarwal-Banka, P; Seal, A

    2016-11-01

    Endophytic microbes isolated from plants growing in nutrient-deficient environments often possess properties that improve nutrition of agriculturally important plants. A consortium of non-rhizobial endophytic microbes isolated from a macrophyte Typha angustifolia growing in the marginal wetlands associated with a Uranium mine was characterized for their beneficial effect on rice and the mechanisms of growth promotion were investigated. The microbes were identified and characterized for their potential plant growth promoting (PGP) properties. Effect of these microbes on nitrogen (N)-metabolism of rice was tested as Typha endophytes were predominantly (N)-fixing. Relative N-use efficiency and expression of genes involved in N-uptake and assimilation were investigated in treated plants. Evidence of horizontal gene transfer (HGT) of dinitrogen reductase gene was observed within the consortium from a Pseudomonas stutzeri strain. The consortium behaved as plant probiotic and showed substantial growth benefits to Typha, their natural host as well as to rice. Typha endophytes colonized rice endosphere significantly increasing biomass, shoot length and chlorophyll content in rice plants both under N-sufficient and N-deficient conditions. N-uptake and assimilation genes were upregulated in plants treated with the endophytes even after three weeks post infection. Our results suggested, HGT of nitrogen-fixation trait to be highly prevalent among endophytes isolated from nutrient-poor habitats of the uranium mine. A long-term nitrogen deficiency response in the treated plants was elicited by the consortium improving N-uptake, assimilation and relative N-use efficiency of rice plants. This appeared to be at least one of the main strategies of plant growth promotion.

  16. UV-B induced differential effect on growth and nitrogen metabolism in two cyanobacteria under copper toxicity.

    PubMed

    Singh, V P; Srivastava, P K; Prasad, S M

    2012-12-22

    In the present study, impact of low (UV-B(L): 0.1 μmol m(-2) s(-1)) and high (UV-BH: 1.0 μmol m(-2) s(-1)) fluence rates of ultraviolet-B on growth and nitrogen metabolism in two cyanobacteria: Phormidium foveolarum and Nostoc muscorum under copper toxicity (2 and 5 μM) was investigated after 24 and 72 h of experiments. Copper and UV-BH treatment suppressed growth but more in N. muscorum which was accompanied by significant accumulation of Cu. Nitrate and nitrite uptake rates and activities of nitrogen assimilating enzymes i.e. nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS) and glutamate synthase (GOGAT) except glutamate dehydrogenase activity (GDH; aminating) were decreased following treatments of Cu and UV-BH, and under combined treatments the effect was greater. On contrary, UV-BL declined Cu toxicity significantly. The study concludes that Cu and UV-BH suppressed the activity of NR, NiR, GS and GOGAT (except GDH) hence decreased growth. However, UV-BL showed cross tolerance in test organisms against Cu toxicity up to certain extent. Phormidium foveolarum is comparatively less sensitive against UV-BH and excess Cu, a situation likely exists in nature, hence it may be used as a biofertilizer for sustainable agriculture.

  17. Integration of carbon and nitrogen metabolism with energy production is crucial to light acclimation in the cyanobacterium Synechocystis.

    PubMed

    Singh, Abhay K; Elvitigala, Thanura; Bhattacharyya-Pakrasi, Maitrayee; Aurora, Rajeev; Ghosh, Bijoy; Pakrasi, Himadri B

    2008-09-01

    Light drives the production of chemical energy and reducing equivalents in photosynthetic organisms required for the assimilation of essential nutrients. This process also generates strong oxidants and reductants that can be damaging to the cellular processes, especially during absorption of excess excitation energy. Cyanobacteria, like other oxygenic photosynthetic organisms, respond to increases in the excitation energy, such as during exposure of cells to high light (HL) by the reduction of antenna size and photosystem content. However, the mechanism of how Synechocystis sp. PCC 6803, a cyanobacterium, maintains redox homeostasis and coordinates various metabolic processes under HL stress remains poorly understood. In this study, we have utilized time series transcriptome data to elucidate the global responses of Synechocystis to HL. Identification of differentially regulated genes involved in the regulation, protection, and maintenance of redox homeostasis has offered important insights into the optimized response of Synechocystis to HL. Our results indicate a comprehensive integrated homeostatic interaction between energy production (photosynthesis) and energy consumption (assimilation of carbon and nitrogen). In addition, measurements of physiological parameters under different growth conditions showed that integration between the two processes is not a consequence of limitations in the external carbon and nitrogen levels available to the cells. We have also discovered the existence of a novel glycosylation pathway, to date known as an important nutrient sensor only in eukaryotes. Up-regulation of a gene encoding the rate-limiting enzyme in the hexosamine pathway suggests a regulatory role for protein glycosylation in Synechocystis under HL.

  18. Dietary protein source affects lipid metabolism in the European seabass (Dicentrarchus labrax).

    PubMed

    Dias, J; Alvarez, M J; Arzel, J; Corraze, G; Diez, A; Bautista, J M; Kaushik, S J

    2005-09-01

    The study was undertaken to evaluate the effects of dietary protein sources on lipogenesis and fat deposition in a marine teleost, the European seabass (Dicentrarchus labrax). Four isonitrogenous (crude protein (CP, Nx6.25), 44% DM) and isoenergetic (22-23 kJ/g DM) diets were formulated to contain one of the following as the major protein source: fish meal (FM), one of two soy protein concentrates (SPC) and corn gluten meal (CGM). Apparent digestibility coefficients of the diets and raw ingredients, as well as soluble nitrogen (ammonia and urea) and phosphorus excretion were measured. Growth rates of seabass fed plant protein-based diets were significantly lower than those fed fish meal based diet. The protein utilisation was strongly correlated to the dietary essential amino acids index. Measurements of N excretion (ammonia and urea nitrogen) confirmed these data. Daily fat gain at the whole body level ranged between 1.1 to 1.7 g/kg BW, with the highest values being recorded in fish fed the fish meal based diet. Levels of plasma triglycerides and cholesterol were lower in fish fed soy protein diets than in those fed the diet solely based on fish meal. Soy protein rich diets decreased the activities of selected hepatic lipogenic enzymes (glucose 6-phosphate dehydrogenase, malic enzyme, ATP-citrate lysase, acetylcoenzyme A carboxylase and fatty acid synthetase). Highest lipogenic enzyme activities where found in fish fed the fish meal diet, except for fatty acid synthetase which was increased in seabass fed the corn-gluten meal based diets. Overall data suggest that dietary protein sources affects fat deposition and the lipogenic potential in European seabass.

  19. Potato Snakin-1 Gene Silencing Affects Cell Division, Primary Metabolism, and Cell Wall Composition1[W

    PubMed Central

    Nahirñak, Vanesa; Almasia, Natalia Inés; Fernandez, Paula Virginia; Hopp, Horacio Esteban; Estevez, José Manuel; Carrari, Fernando; Vazquez-Rovere, Cecilia

    2012-01-01

    Snakin-1 (SN1) is an antimicrobial cysteine-rich peptide isolated from potato (Solanum tuberosum) that was classified as a member of the Snakin/Gibberellic Acid Stimulated in Arabidopsis protein family. In this work, a transgenic approach was used to study the role of SN1 in planta. Even when overexpressing SN1, potato lines did not show remarkable morphological differences from the wild type; SN1 silencing resulted in reduced height, which was accompanied by an overall reduction in leaf size and severe alterations of leaf shape. Analysis of the adaxial epidermis of mature leaves revealed that silenced lines had 70% to 90% increases in mean cell size with respect to wild-type leaves. Consequently, the number of epidermal cells was significantly reduced in these lines. Confocal microscopy analysis after agroinfiltration of Nicotiana benthamiana leaves showed that SN1-green fluorescent protein fusion protein was localized in plasma membrane, and bimolecular fluorescence complementation assays revealed that SN1 self-interacted in vivo. We further focused our study on leaf metabolism by applying a combination of gas chromatography coupled to mass spectrometry, Fourier transform infrared spectroscopy, and spectrophotometric techniques. These targeted analyses allowed a detailed examination of the changes occurring in 46 intermediate compounds from primary metabolic pathways and in seven cell wall constituents. We demonstrated that SN1 silencing affects cell division, leaf primary metabolism, and cell wall composition in potato plants, suggesting that SN1 has additional roles in growth and development beyond its previously assigned role in plant defense. PMID:22080603

  20. SIRT1 stimulation by polyphenols is affected by their stability and metabolism.

    PubMed

    de Boer, Vincent C J; de Goffau, Marcus C; Arts, Ilja C W; Hollman, Peter C H; Keijer, Jaap

    2006-07-01

    Silent information regulator two ortholog 1 (SIRT1) is the human ortholog of the yeast sir2 protein; one of the most important regulators of lifespan extension by caloric restriction in several organisms. Dietary polyphenols, abundant in vegetables, fruits, cereals, wine and tea, were reported to stimulate the deacetylase activity of recombinant SIRT1 protein and could therefore be potential regulators of aging associated processes. However, inconsistent data between effects of polyphenols on the recombinant SIRT1 and on in vivo SIRT1, led us to investigate the influence of (1) stability of polyphenols under experimental conditions and (2) metabolism of polyphenols in human HT29 cells, on stimulation of SIRT1. With an improved SIRT1 deacetylation assay we found three new polyphenolic stimulators. Epigallocatechin galate (EGCg, 1.76-fold), epicatechin galate (ECg, 1.85-fold) and myricetin (3.19-fold) stimulated SIRT1 under stabilizing conditions, whereas without stabilization, these polyphenols strongly inhibited SIRT1, probably due to H2O2 formation. Using metabolically active HT29 cells we were able to show that quercetin (a stimulator of recombinant SIRT1) could not stimulate intracellular SIRT1. The major quercetin metabolite in humans, quercetin 3-O-glucuronide, slightly inhibited the recombinant SIRT1 activity which explains the lack of stimulatory action of quercetin in HT29 cells. This study shows that the stimulation of SIRT1 is strongly affected by polyphenol stability and metabolism, therefore extrapolation of in vitro SIRT1 stimulation results to physiological effects should be done with caution.

  1. Arachidonic Acid and Eicosapentaenoic Acid Metabolism in Juvenile Atlantic Salmon as Affected by Water Temperature

    PubMed Central

    Norambuena, Fernando; Morais, Sofia; Emery, James A.; Turchini, Giovanni M.

    2015-01-01

    Salmons raised in aquaculture farms around the world are increasingly subjected to sub-optimal environmental conditions, such as high water temperatures during summer seasons. Aerobic scope increases and lipid metabolism changes are known plasticity responses of fish for a better acclimation to high water temperature. The present study aimed at investigating the effect of high water temperature on the regulation of fatty acid metabolism in juvenile Atlantic salmon fed different dietary ARA/EPA ratios (arachidonic acid, 20:4n-6/ eicosapentaenoic acid, 20:5n-3), with particular focus on apparent in vivo enzyme activities and gene expression of lipid metabolism pathways. Three experimental diets were formulated to be identical, except for the ratio EPA/ARA, and fed to triplicate groups of Atlantic salmon (Salmo salar) kept either at 10°C or 20°C. Results showed that fatty acid metabolic utilisation, and likely also their dietary requirements for optimal performance, can be affected by changes in their relative levels and by environmental temperature in Atlantic salmon. Thus, the increase in temperature, independently from dietary treatment, had a significant effect on the β-oxidation of a fatty acid including EPA, as observed by the apparent in vivo enzyme activity and mRNA expression of pparα -transcription factor in lipid metabolism, including β-oxidation genes- and cpt1 -key enzyme responsible for the movement of LC-PUFA from the cytosol into the mitochondria for β-oxidation-, were both increased at the higher water temperature. An interesting interaction was observed in the transcription and in vivo enzyme activity of Δ5fad–time-limiting enzyme in the biosynthesis pathway of EPA and ARA. Such, at lower temperature, the highest mRNA expression and enzyme activity was recorded in fish with limited supply of dietary EPA, whereas at higher temperature these were recorded in fish with limited ARA supply. In consideration that fish at higher water temperature

  2. Food odors trigger an endocrine response that affects food ingestion and metabolism.

    PubMed

    Lushchak, Oleh V; Carlsson, Mikael A; Nässel, Dick R

    2015-08-01

    Food odors stimulate appetite and innate food-seeking behavior in hungry animals. The smell of food also induces salivation and release of gastric acid and insulin. Conversely, sustained odor exposure may induce satiation. We demonstrate novel effects of food odors on food ingestion, metabolism and endocrine signaling in Drosophila melanogaster. Acute exposure to attractive vinegar odor triggers a rapid and transient increase in circulating glucose, and a rapid upregulation of genes encoding the glucagon-like hormone adipokinetic hormone (AKH), four insulin-like peptides (DILPs) and some target genes in peripheral tissues. Sustained exposure to food odors, however, decreases food intake. Hunger-induced strengthening of synaptic signaling from olfactory sensory neurons (OSNs) to brain neurons increases food-seeking behavior, and conversely fed flies display reduced food odor sensitivity and feeding. We show that increasing the strength of OSN signaling chronically by genetic manipulation of local peptide neuromodulation reduces feeding, elevates carbohydrates and diminishes lipids. Furthermore, constitutively strengthened odor sensitivity altered gene transcripts for AKH, DILPs and some of their targets. Thus, we show that food odor can induce a transient anticipatory endocrine response, and that boosted sensitivity to this odor affects food intake, as well as metabolism and hormonal signaling.

  3. Rice Debranching Enzyme Isoamylase3 Facilitates Starch Metabolism and Affects Plastid Morphogenesis

    PubMed Central

    Yun, Min-Soo; Umemoto, Takayuki; Kawagoe, Yasushi

    2011-01-01

    Debranching enzymes, which hydrolyze α-1 and 6-glucosidic linkages in α-polyglucans, play a dual role in the synthesis and degradation of starch in plants. A transposon-inserted rice mutant of isoamylase3 (isa3) contained an increased amount of starch in the leaf blade at the end of the night, indicating that ISA3 plays a role in the degradation of transitory starch during the night. An epitope-tagged ISA3 expressed in Escherichia coli exhibited hydrolytic activity on β-limit dextrin and amylopectin. We investigated whether ISA3 plays a role in amyloplast development and starch metabolism in the developing endosperm. ISA3–green fluorescent protein (GFP) fusion protein expressed under the control of the rice ISA3 promoter was targeted to the amyloplast stroma in the endosperm. Overexpression of ISA3 in the sugary1 mutant, which is deficient in ISA1 activity, did not convert water-soluble phytoglycogen to starch granules, indicating that ISA1 and ISA3 are not functionally redundant. Both overexpression and loss of function of ISA3 in the endosperm generated pleomorphic amyloplasts and starch granules. Furthermore, chloroplasts in the leaf blade of isa3 seedlings were large and pleomorphic. These results suggest that ISA3 facilitates starch metabolism and affects morphological characteristics of plastids in rice. PMID:21551159

  4. Provenance, life span, and phylogeny do not affect grass species' responses to nitrogen and phosphorus.

    PubMed

    Seabloom, Eric W; Benfield, Cara D; Borer, Elizabeth T; Stanley, Amanda G; Kaye, Thomas N; Dunwiddie, Peter W

    2011-09-01

    Successful conservation management requires an understanding of how species respond to intervention. Native and exotic species may respond differently to management interventions due to differences arising directly from their origin (i.e., provenance) or indirectly due to biased representations of different life history types (e.g., annual vs. perennial life span) or phylogenetic lineages among provenance (i.e., native or exotic origin) groups. Thus, selection of a successful management regime requires knowledge of the life history and provenance-bias in the local flora and an understanding of the interplay between species characteristics across existing environmental gradients in the landscape. Here we tested whether provenance, phylogeny, and life span interact to determine species distributions along natural gradients of soil chemistry (e.g., soil nitrogen and phosphorus) in 10 upland prairie sites along a 600-km latitudinal transect running from southern Vancouver Island in British Columbia, Canada, to the Willamette Valley in Oregon, USA. We found that soil nitrate, phosphorus, and pH exerted strong control over community composition. However, species distributions along environmental gradients were unrelated to provenance, life span, or phylogenetic groupings. We then used a greenhouse experiment to more precisely measure the response of common grass species to nitrogen and phosphorus supply. As with the field data, species responses to nutrient additions did not vary as a function of provenance, life span, or phylogeny. Native and exotic species differed strongly in the relationship between greenhouse-measured tolerance of low nutrients and field abundance. Native species with the greatest ability to maintain biomass production at low nutrient supply rates were most abundant in field surveys, as predicted by resource competition theory. In contrast, there was no relationship between exotic-species biomass at low nutrient levels and field abundance. The

  5. The effect of zilpaterol hydrochloride supplementation on energy metabolism and nitrogen and carbon retention of steers fed at maintenance and fasting intake levels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An indirect calorimetry trial examined energy metabolism, apparent nutrient digestibility (appND), carbon retention (CR) and nitrogen retention (NR) of cattle supplemented with zilpaterol hydrochloride (Z). Beef steers (n=20; 463 ± 14 kg) blocked (n=5) by weight and source were individually fed and ...

  6. Nitrogen Assimilation and Protein Synthesis in Wheat Seedlings as Affected by Mineral Nutrition. II. Micronutrients 1

    PubMed Central

    Harper, James E.; Paulsen, Gary M.

    1969-01-01

    Activity of nitrate reductase from Triticum aestivum L. seedlings was decreased by deficiencies of molybdenum, zinc, and chlorine. Nitrate accumulated in molybdenum-deficient seedlings, declined in zinc-deficient seedlings, and was unaffected by the other micronutrient treatments. Glutamic acid dehydrogenase activity was decreased by deficiency of molybdenum, the only nutrient that affected the enzyme. Glutamine synthetase activity was decreased only by copper deficiency, and glutamic-oxaloacetic transaminase was not affected by any micronutrient deficiencies. Incorporation of 14C-leucine into protein by wheat seedlings was increased by molybdenum deficiency, apparently because of decreased inhibition from endogenous amino acids, and was decreased by copper deficiency. Protein content was not affected significantly by the micronutrient treatments. PMID:16657114

  7. Regulation of nitrogen metabolism is altered in a glnB mutant strain of Rhizobium leguminosarum.

    PubMed

    Amar, M; Patriarca, E J; Manco, G; Bernard, P; Riccio, A; Lamberti, A; Defez, R; Iaccarino, M

    1994-02-01

    We isolated a Rhizobium leguminosarum mutant strain altered in the glnB gene. This event, which has never been described in the Rhizobiaceae, is rare in comparison to mutants isolated in the contiguous gene, glnA. The glnB mutation removes the glnBA promoter but in vivo does not prevent glnA expression from its own promoter, which is not nitrogen regulated. The glnB mutant strain does not grow on nitrate as a sole nitrogen source and it is Nod+, Fix+. Two -24/-12 promoters, for the glnII and glnBA genes, are constitutively expressed in the glnB mutant, while two -35/-10-like promoters for glnA and ntrBC are unaffected. We propose that the glnB gene product, the PII protein, plays a negative role in the ability of NtrC to activate transcription from its target promoters and a positive role in the mechanism of nitrate utilization.

  8. Does nitrogen fertilizer application rate to corn affect nitrous oxide emissions from the rotated soybean crop?

    PubMed

    Iqbal, Javed; Mitchell, David C; Barker, Daniel W; Miguez, Fernando; Sawyer, John E; Pantoja, Jose; Castellano, Michael J

    2015-05-01

    Little information exists on the potential for N fertilizer application to corn ( L.) to affect NO emissions during subsequent unfertilized crops in a rotation. To determine if N fertilizer application to corn affects NO emissions during subsequent crops in rotation, we measured NO emissions for 3 yr (2011-2013) in an Iowa, corn-soybean [ (L.) Merr.] rotation with three N fertilizer rates applied to corn (0 kg N ha, the recommended rate of 135 kg N ha, and a high rate of 225 kg N ha); soybean received no N fertilizer. We further investigated the potential for a winter cereal rye ( L.) cover crop to interact with N fertilizer rate to affect NO emissions from both crops. The cover crop did not consistently affect NO emissions. Across all years and irrespective of cover crop, N fertilizer application above the recommended rate resulted in a 16% increase in mean NO flux rate during the corn phase of the rotation. In 2 of the 3 yr, N fertilizer application to corn (0-225 kg N ha) did not affect mean NO flux rates from the subsequent unfertilized soybean crop. However, in 1 yr after a drought, mean NO flux rates from the soybean crops that received 135 and 225 kg N ha N application in the corn year were 35 and 70% higher than those from the soybean crop that received no N application in the corn year. Our results are consistent with previous studies demonstrating that cover crop effects on NO emissions are not easily generalizable. When N fertilizer affects NO emissions during a subsequent unfertilized crop, it will be important to determine if total fertilizer-induced NO emissions are altered or only spread across a greater period of time.

  9. Fatty acid metabolism during maturation affects glucose uptake and is essential to oocyte competence.

    PubMed

    Paczkowski, M; Schoolcraft, W B; Krisher, R L

    2014-10-01

    Fatty acid β-oxidation (FAO) is essential for oocyte maturation in mice. The objective of this study was to determine the effect of etomoxir (a FAO inhibitor; 100 μM), carnitine (1 mM), and palmitic acid (1 or 100 μM) during maturation on metabolism and gene expression of the oocyte and cumulus cells, and subsequent embryo development in the mouse. Carnitine significantly increased embryo development, while there was a decrease in development following maturation with 100 μM palmitic acid or etomoxir (P<0.05) treatment. Glucose consumption per cumulus-oocyte complex (COC) was decreased after treatment with carnitine and increased following etomoxir treatment (P<0.05). Intracellular oocyte lipid content was decreased after carnitine or etomoxir exposure (P<0.05). Abundance of Slc2a1 (Glut1) was increased after etomoxir treatment in the oocyte and cumulus cells (P<0.05), suggesting stimulation of glucose transport and potentially the glycolytic pathway for energy production when FAO is inhibited. Abundance of carnitine palmitoyltransferase 2 (Cpt2) tended to increase in oocytes (P=0.1) after treatment with 100 μM palmitic acid and in cumulus cells after exposure to 1 μM palmitic acid (P=0.07). Combined with carnitine, 1 μM palmitic acid increased the abundance of Acsl3 (P<0.05) and Cpt2 tended to increase (P=0.07) in cumulus cells, suggesting FAO was increased during maturation in response to stimulators and fatty acids. In conclusion, fatty acid and glucose metabolism are related to the mouse COC, as inhibition of FAO increases glucose consumption. Stimulation of FAO decreases glucose consumption and lipid stores, positively affecting subsequent embryo development, while an overabundance of fatty acid or reduced FAO negatively affects oocyte quality.

  10. Glucoraphasatin and glucoraphenin, a redox pair of glucosinolates of brassicaceae, differently affect metabolizing enzymes in rats.

    PubMed

    Barillari, Jessica; Iori, Renato; Broccoli, Massimiliano; Pozzetti, Laura; Canistro, Donatella; Sapone, Andrea; Bonamassa, Barbara; Biagi, Gian Luigi; Paolini, Moreno

    2007-07-11

    Brassica vegetables are an important dietary source of glucosinolates (GLs), whose breakdown products exhibit anticancer activity. The protective properties of Brassicaceae are believed to be due to the inhibition of Phase-I or induction of Phase-II xenobiotic metabolizing enzymes (XMEs), thus enhancing carcinogen clearance. To study whether GLs affect XMEs and the role of their chemical structure, we focused on two alkylthio GLs differing in the oxidation degree of the side chain sulfur. Male Sprague-Dawley rats were supplemented (per oral somministration by gavage) with either glucoraphasatin (4-methylthio-3-butenyl GL; GRH) or glucoraphenin (4-methylsulfinyl-3-butenyl GL; GRE), at 24 or 120 mg/kg body weight in a single or repeated fashion (daily for four consecutive days), and hepatic microsomes were prepared for XME analyses. Both GLs were able to induce XMEs, showing different induction profiles. While the inductive effect was stronger after multiple administration of the higher GRH dosage, the single lower GRE dose was the most effective in boosting cytochrome P-450 (CYP)-associated monooxygenases and the postoxidative metabolism. CYP3A1/2 were the most affected isoforms by GRH treatment, whereas GRE induced mainly CYP1A2 supported oxidase. Glutathione S-transferase increased up to approximately 3.2-fold after a single (lower) GRE dose and UDP-glucuronosyl transferase up to approximately 2-fold after four consecutive (higher) GRH doses. In conclusion, the induction profile of these GLs we found is not in line with the chemopreventive hypothesis. Furthermore, the oxidation degree of the side chain sulfur of GLs seems to exert a crucial role on XME modulation.

  11. Proteomic analysis revealed nitrogen-mediated metabolic, developmental, and hormonal regulation of maize (Zea mays L.) ear growth.

    PubMed

    Liao, Chengsong; Peng, Yunfeng; Ma, Wei; Liu, Renyi; Li, Chunjian; Li, Xuexian

    2012-09-01

    Optimal nitrogen (N) supply is critical for achieving high grain yield of maize. It is well established that N deficiency significantly reduces grain yield and N oversupply reduces N use efficiency without significant yield increase. However, the underlying proteomic mechanism remains poorly understood. The present field study showed that N deficiency significantly reduced ear size and dry matter accumulation in the cob and grain, directly resulting in a significant decrease in grain yield. The N content, biomass accumulation, and proteomic variations were further analysed in young ears at the silking stage under different N regimes. N deficiency significantly reduced N content and biomass accumulation in young ears of maize plants. Proteomic analysis identified 47 proteins with significant differential accumulation in young ears under different N treatments. Eighteen proteins also responded to other abiotic and biotic stresses, suggesting that N nutritional imbalance triggered a general stress response. Importantly, 24 proteins are involved in regulation of hormonal metabolism and functions, ear development, and C/N metabolism in young ears, indicating profound impacts of N nutrition on ear growth and grain yield at the proteomic level.

  12. Mineral and nitrogen metabolic studies on Skylab flights and comparison with effects of earth long-term recumbency

    NASA Technical Reports Server (NTRS)

    Whedon, G. D.; Reid, J.; Lutwak, L.; Rambaut, P.; Whittle, M.; Leach, C.; Smith, M.

    1976-01-01

    A metabolic study of the effects of space flight on various chemical elements, particularly those with special relevance to the musculo-skeletal system, was carried out on the nine astronauts who participated in the three Skylab flights of 28, 59 and 84 days in 1973-1974. The study required of the cooperating crewmen constant dietary intake, continuous 24-hour urine collections and total fecal collections for 21-31 days before each flight, throughout each flight and for 17-18 days post-flight. Increases in urinary calcium and negative calcium balances during space flight were generally similar to those found in previous immobilization and bedrest studies. The persistence of these alterations in calcium metabolism throughout the flights suggested that calcium losses would continue in weightlessness for a very long time. Significant losses of nitrogen and phosphorus occurred, associated with observed reduction in muscle tissue. Both mineral and muscle losses occurred despite rigorous exercise regimens in flight. It was concluded that unless protective measures can be developed, capable musculo-skeletal function is likely to be impaired in space flights, ultimately to be conducted to Mars, of 1-1/2 to 3 years duration.

  13. Mineral and nitrogen metabolic studies on Skylab flights and comparison with effects of earth long-term recumbency.

    PubMed

    Whedon, G D; Lutwak, L; Rambaut, P; Whittle, M; Leach, C; Reid, J; Smith, M

    1976-01-01

    A metabolic study of the effects of space flight on various chemical elements, particularly those with special relevance to the musculo-skeletal system, was carried out on the nine astronauts who participated in the three Skylab flights of 28, 59 and 84 days in 1973-1974. The study required of the cooperating crewmen constant dietary intake, continuous 24-hour urine collections and total fecal collections for 21-31 days before each flight, throughout each flight and for 17-18 days post-flight. Increases in urinary calcium and negative calcium balances during space flight were generally similar to those found in previous immobilization and bedrest studies. The persistence of these alterations in calcium metabolism throughout the flights suggested that calcium losses would continue in weightlessness for a very long time. Significant losses of nitrogen and phosphorus occurred, associated with observed reduction in muscle tissue. Both mineral and muscle losses occurred despite vigorous exercise regimens in flight. It was concluded that unless protective measures can be developed, capable musculo-skeletal function is likely to be impaired in space flights, ultimately to be conducted to Mars, of 11/2 to 3 years duration.

  14. Biodegradation study of crop residues as affected by exogenous inorganic nitrogen and fungal inoculants.

    PubMed

    Gaind, Sunita; Pandey, Alok Kumar; Lata

    2005-01-01

    The comparative decomposition of chickpea residue, and chopped and unchopped wheat straw was investigated in pits for 120 days. Microbial biomass, humus, C/N ratio, pH, Electrical conductivity (EC), dehydrogenase, alkaline phosphatase, cellulase, xylanase, total phenol and soluble protein were determined to assess their response to the addition of inorganic nitrogen and mixed fungal inoculum of Aspergillus nidulans, Phanerochaete chrysosporium and Trichoderma viride. The evaluation of physico-chemical parameters (organic matter, organic carbon, N, C/N, pH, EC, microbial biomass) revealed that by supplementing unchopped wheat straw with 1% urea and mixed fungal inoculum, a lowest C/N ratio of 10.7, lowest biomass of 9.54 and highest humus content of 13% can be achieved within 3 months. Germination of Lepidium sativum (cress seeds) showed a germination index >60%, in this treatment. The enzyme assay for dehydrogenase indicated highest microbial activity in uninoculated treatments compared to fungal inoculated counterparts, in the second month sampling (active phase of composting). However, cellulase and xylanase activity showed an upward trend during curing phase of composting. Chickpea residue compost, though resulted in a C/N ratio of 17.3, but its germination index was less than 60%. The rapid quality tests conducted for H2S, NH3, NO3 and starch confirmed the stability and maturity of finished compost prepared from wheat straw through microbial inoculants.

  15. A global analysis of fine root production as affected by soil nitrogen and phosphorus.

    PubMed

    Yuan, Z Y; Chen, Han Y H

    2012-09-22

    Fine root production is the largest component of belowground production and plays substantial roles in the biogeochemical cycles of terrestrial ecosystems. The increasing availability of nitrogen (N) and phosphorus (P) due to human activities is expected to increase aboveground net primary production (ANNP), but the response of fine root production to N and P remains unclear. If roots respond to nutrients as ANNP, fine root production is anticipated to increase with increasing soil N and P. Here, by synthesizing data along the nutrient gradient from 410 natural habitats and from 469 N and/or P addition experiments, we showed that fine root production increased in terrestrial ecosystems with an average increase along the natural N gradient of up to 0.5 per cent with increasing soil N. Fine root production also increased with soil P in natural conditions, particularly at P < 300 mg kg(-1). With N, P and combined N + P addition, fine root production increased by a global average of 27, 21 and 40 per cent, respectively. However, its responses differed among ecosystems and soil types. The global average increases in fine root production are lower than those of ANNP, indicating that above- and belowground counterparts are coupled, but production allocation shifts more to aboveground with higher soil nutrients. Our results suggest that the increasing fertilizer use and combined N deposition at present and in the future will stimulate fine root production, together with ANPP, probably providing a significant influence on atmospheric CO(2) emissions.

  16. Long-term trends of changes in pine and oak foliar nitrogen metabolism in response to chronic nitrogen amendments at Harvard Forest, MA.

    PubMed

    Minocha, Rakesh; Turlapati, Swathi A; Long, Stephanie; McDowell, William H; Minocha, Subhash C

    2015-08-01

    We evaluated the long-term (1995-2008) trends in foliar and sapwood metabolism, soil solution chemistry and tree mortality rates in response to chronic nitrogen (N) additions to pine and hardwood stands at the Harvard Forest Long Term Ecological Research (LTER) site. Common stress-related metabolites like polyamines (PAs), free amino acids (AAs) and inorganic elements were analyzed for control, low N (LN, 50 kg NH4NO3 ha(-1) year(-1)) and high N (HN, 150 kg NH4NO3 ha(-1) year(-1)) treatments. In the pine stands, partitioning of excess N into foliar PAs and AAs increased with both N treatments until 2002. By 2005, several of these effects on N metabolites disappeared for HN, and by 2008 they were mostly observed for LN plot. A significant decline in foliar Ca and P was observed mostly with HN for a few years until 2005. However, sapwood data actually showed an increase in Ca, Mg and Mn and no change in PAs in the HN plot for 2008, while AAs data revealed trends that were generally similar to foliage for 2008. Concomitant with these changes, mortality data revealed a large number of dead trees in HN pine plots by 2002; the mortality rate started to decline by 2005. Oak trees in the hardwood plot did not exhibit any major changes in PAs, AAs, nutrients and mortality rate with LN treatment, indicating that oak trees were able to tolerate the yearly doses of 50 kg NH4NO3 ha(-1) year(-1). However, HN trees suffered from physiological and nutritional stress along with increased mortality in 2008. In this case also, foliar data were supported by the sapwood data. Overall, both low and high N applications resulted in greater physiological stress to the pine trees than the oaks. In general, the time course of changes in metabolic data are in agreement with the published reports on changes in soil chemistry and microbial community structure, rates of soil carbon sequestration and production of woody biomass for this chronic N study. This correspondence of selected metabolites

  17. Processes affecting the transport of nitrogen in groundwater and factors related to slope position

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrate (NO3-) pollution of water resources has been a major problem for years, causing contaminated water supplies, harmful effects on human health, and widespread eutrophication of fresh water resources. The main objectives of this study were to: 1) understand the processes affecting NO3- transpor...

  18. Stand age affects fertilizer nitrogen response in first-year corn following alfalfa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The amount of N that alfalfa (Medicago sativa L.) provides to subsequent first-year corn (Zea mays L.) depends, in part, on the age of alfalfa at termination. Our objective was to determine how alfalfa stand age affects N availability and fertilizer N requirements for first-year corn. Fertilizer N w...

  19. Effects of hypoxia on the energy status and nitrogen metabolism of African lungfish during aestivation in a mucus cocoon.

    PubMed

    Loong, A M; Ang, S F; Wong, W P; Pörtner, H O; Bock, C; Wittig, R; Bridges, C R; Chew, S F; Ip, Y K

    2008-09-01

    We examined the energy status, nitrogen metabolism and hepatic glutamate dehydrogenase activity in the African lungfish Protopterus annectens during aestivation in normoxia (air) or hypoxia (2% O(2) in N(2)), with tissues sampled on day 3 (aerial exposure with preparation for aestivation), day 6 (entering into aestivation) or day 12 (undergoing aestivation). There was no accumulation of ammonia in tissues of fish exposed to normoxia or hypoxia throughout the 12-day period. Ammonia toxicity was avoided by increased urea synthesis and/or decreased endogenous N production (as ammonia), but the dependency on these two mechanisms differed between the normoxic and the hypoxic fish. The rate of urea synthesis increased 2.4-fold, with only a 12% decrease in the rate of N production in the normoxic fish. By contrast, the rate of N production in the hypoxic fish decreased by 58%, with no increase in the rate of urea synthesis. Using in vivo (31)P NMR spectroscopy, it was demonstrated that hypoxia led to significantly lower ATP concentration on day 12 and significantly lower creatine phosphate concentration on days 1, 6, 9 and 12 in the anterior region of the fish as compared with normoxia. Additionally, the hypoxic fish had lower creatine phosphate concentration in the middle region than the normoxic fish on day 9. Hence, lowering the dependency on increased urea synthesis to detoxify ammonia, which is energy intensive by reducing N production, would conserve cellular energy during aestivation in hypoxia. Indeed, there were significant increases in glutamate concentrations in tissues of fish aestivating in hypoxia, which indicates decreases in its degradation and/or transamination. Furthermore, there were significant increases in the hepatic glutamate dehydrogenase (GDH) amination activity, the amination/deamination ratio and the dependency of the amination activity on ADP activation in fish on days 6 and 12 in hypoxia, but similar changes occurred only in the normoxic fish

  20. Dietary L-carnitine affects periparturient nutrient metabolism and lactation in multiparous cows.

    PubMed

    Carlson, D B; McFadden, J W; D'Angelo, A; Woodworth, J C; Drackley, J K

    2007-07-01

    The objectives of this study were to determine the effects of dietary L-carnitine supplementation on liver lipid accumulation, hepatic nutrient metabolism, and lactation in multiparous cows during the periparturient period. Cows were assigned to treatments at d -25 relative to expected calving date and remained on the experiment until 56 d in milk. Treatments were 4 amounts of supplemental dietary carnitine: control (0 g/d of L-carnitine; n = 14); low carnitine (LC, 6 g/d; n = 11); medium carnitine (MC, 50 g/d; n = 12); and high carnitine (HC, 100 g/d; n = 12). Carnitine was supplied by mixing a feed-grade carnitine supplement with 113.5 g of ground corn and 113.5 g of dried molasses, which was then fed twice daily as a topdress to achieve desired daily carnitine intakes. Carnitine supplementation began on d -14 relative to expected calving and continued until 21 d in milk. Liver and muscle carnitine concentrations were markedly increased by MC and HC treatments. Milk carnitine concentrations were elevated by all amounts of carnitine supplementation, but were greater for MC and HC than for LC during wk 2 of lactation. Dry matter intake and milk yield were decreased by the HC treatment. The MC and HC treatments increased milk fat concentration, although milk fat yield was unaffected. All carnitine treatments decreased liver total lipid and triacylglycerol accumulation on d 10 after calving. In addition, carnitine-supplemented cows had higher liver glycogen during early lactation. In general, carnitine supplementation increased in vitro palmitate beta-oxidation by liver slices, with MC and HC treatments affecting in vitro palmitate metabolism more potently than did LC. In vitro conversion of Ala to glucose by liver slices was increased by carnitine supplementation independent of dose. The concentration of nonesterified fatty acids in serum was not affected by carnitine. As a result of greater hepatic fatty acid beta-oxidation, plasma beta-hydroxybutyric acid was

  1. Symbiosis between nitrogen-fixing bacteria and Medicago truncatula is not significantly affected by silver and silver sulfide nanomaterials.

    PubMed

    Judy, Jonathan D; Kirby, Jason K; McLaughlin, Mike J; McNear, David; Bertsch, Paul M

    2016-07-01

    Silver (Ag) engineered nanomaterials (ENMs) are being released into waste streams and are being discharged, largely as Ag2S aged-ENMs (a-ENMs), into agroecosystems receiving biosolids amendments. Recent research has demonstrated that biosolids containing an environmentally relevant mixture of ZnO, TiO2, and Ag ENMs and their transformation products, including Ag2S a-ENMs, disrupted the symbiosis between nitrogen-fixing bacteria and legumes. However, this study was unable to unequivocally determine which ENM or combination of ENMs and a-ENMs was responsible for the observed inhibition. Here, we examined further the effects of polyvinylpyrollidone (PVP) coated pristine Ag ENMs (PVP-Ag), Ag2S a-ENMs, and soluble Ag (as AgSO4) at 1, 10, and 100 mg Ag kg(-1) on the symbiosis between the legume Medicago truncatula and the nitrogen-fixing bacterium, Sinorhizobium melliloti in biosolids-amended soil. Nodulation frequency, nodule function, glutathione reductase production, and biomass were not significantly affected by any of the Ag treatments, even at 100 mg kg(-1), a concentration analogous to a worst-case scenario resulting from long-term, repeated biosolids amendments. Our results provide additional evidence that the disruption of the symbiosis between nitrogen-fixing bacteria and legumes in response to a mixture of ENMs in biosolids-amended soil reported previously may not be attributable to Ag ENMs or their transformation end-products. We anticipate these findings will provide clarity to regulators and industry regarding potential unintended consequences to terrestrial ecosystems resulting from of the use of Ag ENMs in consumer products.

  2. Sensitivity of bacterioplankton nitrogen metabolism to eutrophication in sub-tropical coastal waters of Key West, Florida.

    PubMed

    Hoch, Matthew P; Dillon, Kevin S; Coffin, Richard B; Cifuentes, Luis A

    2008-05-01

    Expression of intracellular ammonium assimilation enzymes were used to assess the response of nitrogen (N) metabolism in bacterioplankton to N-loading of sub-tropical coastal waters of Key West, Florida. Specific activities of glutamine synthetase (GS) and total glutamate dehydrogenase (GDHT) were measured on the bacterial size fraction (<0.8 microm) to assess N-deplete versus N-replete metabolic states, respectively. Enzyme results were compared to concentrations of dissolved organic matter and nutrients and to the biomass and production of phytoplankton and bacteria. Concentrations of dissolved inorganic N (DIN), dissolved organic N (DON), and dissolved organic carbon (DOC) positively correlated with specific activities of GDHT and negatively correlated with that of GS. Total dissolved N (TDN) concentration explained 81% of variance in bacterioplankton GDHT:GS activity ratio. The GDHT:GS ratio, TDN, DOC, and bacterial parameters decreased in magnitude along a tidally dynamic trophic gradient from north of Key West to south at the reef tract, which is consistent with the combined effects of localized coastal eutrophication and tidal exchange of seawater from the Southwest Florida Shelf and Florida Strait. The N-replete bacterioplankton north of Key West can regenerate ammonium which sustains primary production transported south to the reef. The range in GDHT:GS ratios was 5-30 times greater than that for commonly used indicators of planktonic eutrophication, which emphasizes the sensitivity of bacterioplankton N-metabolism to changes in N-bioavailability caused by nutrient pollution in sub-tropical coastal waters and utility of GDHT:GS ratio as an bioindicator of N-replete conditions.

  3. Role of nitrogen oxides in the metabolism of ammonia-oxidizing bacteria.

    PubMed

    Kampschreur, M J; Tan, N C G; Picioreanu, C; Jetten, M S M; Schmidt, I; van Loosdrecht, M C M

    2006-02-01

    Ammonia-oxidizing bacteria (AOB) can use oxygen and nitrite as electron acceptors. Nitrite reduction by Nitrosomonas is observed under three conditions: (i) hydrogen-dependent denitrification, (ii) anoxic ammonia oxidation with nitrogen dioxide (NO(2)) and (iii) NO(x)-induced aerobic ammonia oxidation. NO(x) molecules play an important role in the conversion of ammonia and nitrite by AOB. Absence of nitric oxide (NO), which is generally detectable during ammonia oxidation, severely impairs ammonia oxidation by AOB. The lag phase of recovery of aerobic ammonia oxidation was significantly reduced by NO(2) addition. Acetylene inhibition tests showed that NO(2)-dependent and oxygen-dependent ammonia oxidation can be distinguished. Addition of NO(x) increased specific activity of ammonia oxidation, growth rate and denitrification capacity. Together, these findings resulted in a hypothetical model on the role of NO(x) in ammonia oxidation: the NO(x) cycle.

  4. Swine effluent application timing and rate affect nitrogen use efficiency in common bermudagrass.

    PubMed

    Read, J J; Brink, G E; Adeli, A; McGowen, S L

    2008-01-01

    Bermudagrass [Cynodon dactylon (L.) Pers.] hay production is integral to manure management on southeastern swine farms. But swine effluent timing must be synchronized with crop nitrogen (N) demands to decrease the potential for soil N accumulation and nitrate (NO(3)) leaching. Field studies were conducted on a Prentiss sandy loam (coarse-loamy, siliceous, semiactive, thermic Glossic Fragiudult) to determine N-use efficiency (NUE) and residual soil NO(3)-N. Two rates of 10 and 20 cm yr(- 1) ( approximately 260 and 480 kg ha(-1) N, respectively) were applied in four timing treatments: April to September (full season), April to May, June to July, and August to September. Plots were harvested every 7 to 9 wk beginning in June, and soil was sampled in fall after a killing frost and the following spring. Annual uptake of N and P were least in the August to September timing treatment. Doubling the effluent rate increased N uptake 112% in 2000 (from 130 to 276 kg ha(-1)) and 53% in 2001 (from 190 to 290 kg ha(-1)), suggesting 10-cm did not meet crop N demands. Due to low rainfall and decreased forage yield in 2000, doubling the effluent rate led to increased soil NO(3)-N to 30-cm depth in fall 2000 and spring 2001. Averaged across timing treatments, soil NO(3)-N at 5-cm depth ranged from 8.5 mg kg(-1) in non-irrigated controls to 39.6 mg kg(-1) with 20-cm effluent. Results indicate low NUE in the order of 30 to 38% for applications in August to September increase the risk to surface and ground water quality from excess N remaining in soil.

  5. Nutrient addition differentially affects ecological processes of Avicennia germinans in nitrogen versus phosphorus limited mangrove ecosystems

    USGS Publications Warehouse

    Feller, Ilka C.; Lovelock, C.E.; McKee, K.L.

    2007-01-01

    Nutrient over-enrichment is a major threat to marine environments, but system-specific attributes of coastal ecosystems may result in differences in their sensitivity and susceptibility to eutrophication. We used fertilization experiments in nitrogen (N)- and phosphorus (P)-limited mangrove forests to test the hypothesis that alleviating different kinds of nutrient limitation may have different effects on ecosystem structure and function in natural systems. We compared a broad range of ecological processes to determine if these systems have different thresholds where shifts might occur in nutrient limitation. Growth responses indicated N limitation in Avicennia germinans (black mangrove) forests in the Indian River Lagoon (IRL), Florida, and P limitation at Twin Cays, Belize. When nutrient deficiency was relieved, A. germinans grew out of its stunted form by increasing wood relative to leaf biomass and shoot length relative to lateral growth. At the P-limited site, P enrichment (+P) increased specific leaf area, N resorption, and P uptake, but had no effect on P resorption. At the N-limited site, +N increased both N and P resorption, but did not alter biomass allocation. Herbivory was greater at the P-limited site and was unaffected by +P, whereas +N led to increased herbivory at the N-limited site. The responses to nutrient enrichment depended on the ecological process and limiting nutrient and suggested that N- versus P-limited mangroves do have different thresholds. +P had a greater effect on more ecological processes at Twin Cays than did +N at the IRL, which indicated that the P-limited site was more sensitive to nutrient loading. Because of this sensitivity, eutrophication is more likely to cause a shift in nutrient limitation at P-limited Twin Cays than N-limited IRL. ?? 2007 Springer Science+Business Media, LLC.

  6. Particulate Organic Matter Affects Soil Nitrogen Mineralization under Two Crop Rotation Systems.

    PubMed

    Bu, Rongyan; Lu, Jianwei; Ren, Tao; Liu, Bo; Li, Xiaokun; Cong, Rihuan

    2015-01-01

    Changes in the quantity and/or quality of soil labile organic matter between and after different types of cultivation system could play a dominant role in soil nitrogen (N) mineralization. The quantity and quality of particulate organic matter (POM) and potentially mineralizable-N (PMN) contents were measured in soils from 16 paired rice-rapeseed (RR)/cotton-rapeseed (CR) rotations sites in Hubei province, central China. Then four paired soils encompassing low (10th percentile), intermediate (25th and 75th percentiles), and high (90th percentile) levels of soil PMN were selected to further study the effects of POM on soil N mineralization by quantifying the net N mineralization in original soils and soils from which POM was removed. Both soil POM carbon (POM-C) and N (POM-N) contents were 45.8% and 55.8% higher under the RR rotation compared to the CR rotation, respectively. The PMN contents were highly correlated with the POM contents. The PMN and microbial biomass N (MBN) contents concurrently and significantly decreased when POM was removed. The reduction rate of PMN was positively correlated with changes in MBN after the removal of POM. The reduction rates of PMN and MBN after POM removal are lower under RR rotations (38.0% and 16.3%, respectively) than CR rotations (45.6% and 19.5%, respectively). Furthermore, infrared spectroscopy indicated that compounds with low-bioavailability accumulated (e.g., aromatic recalcitrant materials) in the soil POM fraction under the RR rotation but not under the CR rotation. The results of the present study demonstrated that POM plays a vital role in soil N mineralization under different rotation systems. The discrepancy between POM content and composition resulting from different crop rotation systems caused differences in N mineralization in soils.

  7. Cyanobacterial extracts containing microcystins affect the growth, nodulation process and nitrogen uptake of faba bean (Vicia faba L., Fabaceae).

    PubMed

    Lahrouni, Majida; Oufdou, Khalid; Faghire, Mustapha; Peix, Alvaro; El Khalloufi, Fatima; Vasconcelos, Vitor; Oudra, Brahim

    2012-04-01

    The use of irrigation water containing cyanobacterial toxins may generate a negative impact in both yield and quality of agricultural crops causing significant economic losses. We evaluated the effects of microcystins (MC) on the growth, nodulation process and nitrogen uptake of a Faba bean cultivar (Vicia faba L., Fabaceae), particularly the effect of MC on rhizobia-V. faba symbiosis. Three rhizobial strains (RhOF4, RhOF6 and RhOF21), isolated from nodules of local V. faba were tested. The exposure of rhizobia to MC showed that the toxins had a negative effect on the rhizobial growth especially at the highest concentrations of 50 and 100 μg/l. The germination of faba bean seeds was also affected by cyanotoxins. We registered germination rates of 75 and 68.75% at the toxin levels of 50 and 100 μg/l as compared to the control (100%). The obtained results also showed there was a negative effect of MC on plants shoot, root (dry weight) and total number of nodules per plant. Cyanotoxins exposure induced a significant effect on nitrogen assimilation by faba bean seedlings inoculated with selected rhizobial strains RhOF6 and RhOF21, while the effect was not significant on beans seedling inoculated with RhOF4. This behavior of tolerant rhizobia-legumes symbioses may constitute a very important pathway to increase soil fertility and quality and can represent a friendly biotechnological way to remediate cyanotoxins contamination in agriculture.

  8. Critical factors affecting field-scale losses of nitrogen and phosphorus in spring snowmelt runoff in the canadian prairies.

    PubMed

    Liu, Kui; Elliott, Jane A; Lobb, David A; Flaten, Don N; Yarotski, Jim

    2013-01-01

    A long-term, field-scale study in southern Manitoba, Canada, was used to identify the critical factors controlling yearly transport of nitrogen (N) and phosphorus (P) by snowmelt runoff. Flow monitoring and water sampling for total and dissolved N and P were performed at the edge of field. The flow-weighted mean concentrations and loads of N and P for the early (the first half of yearly total volume of snowmelt runoff), late (the second half of yearly total volume of snowmelt runoff), and yearly snowmelt runoff were calculated as response variables. A data set of management practices, weather variables, and hydrologic variables was generated and used as predictor variables. Partial least squares regression analysis indicated that critical factors affecting the water chemistry of snowmelt runoff depended on the water quality variable and stage of runoff. Management practices within each year, such as nitrogen application rate, number of tillage passes, and residue burial ratio, were critical factors for flow-weighted mean concentration of N, but not for P concentration or nutrient loads. However, the most important factors controlling nutrient concentrations and loads were those related to the volume of runoff, including snow water equivalent, flow rate, and runoff duration. The critical factors identified for field-scale yearly snowmelt losses provide the basis for modeling of nutrient losses in southern Manitoba and potentially throughout areas with similar climate in the northern Great Plains region, and will aid in the design of effective practices to reduce agricultural nonpoint nutrient pollution in downstream waters.

  9. Diet affects resting, but not basal metabolic rate of normothermic Siberian hamsters acclimated to winter.

    PubMed

    Gutowski, Jakub P; Wojciechowski, Michał S; Jefimow, Małgorzata

    2011-12-01

    We examined the effect of different dietary supplements on seasonal changes in body mass (m(b)), metabolic rate (MR) and nonshivering thermogenesis (NST) capacity in normothermic Siberian hamsters housed under semi-natural conditions. Once a week standard hamster food was supplemented with either sunflower and flax seeds, rich in polyunsaturated fatty acids (FA), or mealworms, rich in saturated and monounsaturated FA. We found that neither of these dietary supplements affected the hamsters' normal winter decrease in m(b) and fat content nor their basal MR or NST capacity. NST capacity of summer-acclimated hamsters was lower than that of winter-acclimated ones. The composition of total body fat reflected the fat composition of the dietary supplements. Resting MR below the lower critical temperature of the hamsters, and their total serum cholesterol concentration were lower in hamsters fed a diet supplemented with mealworms than in hamsters fed a diet supplemented with seeds. These results indicate that in mealworm-fed hamsters energy expenditure in the cold is lower than in animals eating a seed-supplemented diet, and that the degree of FA unsaturation of diet affects energetics of heterotherms, not only during torpor, but also during normothermy.

  10. Soy processing affects metabolism and disposition of dietary isoflavones in ovariectomized BALB/c mice.

    PubMed

    Allred, Clinton D; Twaddle, Nathan C; Allred, Kimberly F; Goeppinger, Tracy S; Churchwell, Mona I; Ju, Young H; Helferich, William G; Doerge, Daniel R

    2005-11-02

    Soy foods and nutritional supplements are widely consumed for potential health benefits. It was previously shown that isoflavone-supplemented diets, which contained equal genistein equivalents, differentially stimulated mammary tumor growth in athymic mice based on the degree of processing. This paper reports plasma pharmacokinetic analysis and metabolite identification using the parental mouse strain fed the same diets, which contained genistin, mixed isoflavones, Novasoy, soy molasses, or soy flour plus mixed isoflavones. Whereas the degree of soy processing did affect several parameters reflecting isoflavone bioavailability and gut microflora metabolism of daidzein to equol, stimulation of tumor growth correlated significantly with only the plasma concentration of aglycon genistein produced by the diets. This conclusion is consistent with the known estrogen agonist activity of genistein aglycon on mammary tumor growth. Conversely, plasma equol concentration was inversely correlated with the degree of soy processing. Although antagonism of genistein-stimulated tumor growth by equol could explain this result, the very low concentration of aglycon equol in plasma (12-fold lower relative to genistein) is inconsistent with any effect. These findings underscore the importance of food processing, which can remove non-nutritive components from soy, on the pharmacokinetics and pharmacodynamics of isoflavones. Such changes in diet composition affect circulating, and presumably target tissue, concentrations of genistein aglycon, which initiates estrogen receptor-mediated processes required for the stimulation of tumor growth in a mouse model for postmenopausal breast cancer.

  11. Cadmium at high dose perturbs growth, photosynthesis and nitrogen metabolism while at low dose it up regulates sulfur assimilation and antioxidant machinery in garden cress (Lepidium sativum L.).

    PubMed

    Gill, Sarvajeet Singh; Khan, Nafees A; Tuteja, Narendra

    2012-01-01

    Metal contamination of soils has become a worldwide problem and great environmental threat, as these metals accumulate in soils and plants in excess, and enter the food chain. Increased cadmium (Cd) uptake from contaminated soils leads to altered plant metabolism and limits the crop productivity. The experimental crop, Lepidium sativum L. (Garden Cress, Family: Brassicaceae) is a medicinally and economically important plant. An experiment was conducted to examine the effect of different concentrations of Cd (0, 25, 50 or 100 mg kg(-1) soil) on the performance of L. sativum. Cd accumulation in roots and leaves (roots>leaves) increased with the increaseing Cd concentration in soil. High Cd concentration (100mg Cd kg(-1) soil) inhibited the leaf area and plant dry mass and significant decline in net photosynthetic rate (P(N)), stomatal conductance (gs), intercellular CO(2) (Ci), chlorophyll (Chl a, Chl b, total Chl) content, carbonic anhydrase (CA; E.C. 4.2.1.1) activity, nitrate reductase (NR; E.C. 1.6.6.1) activity and nitrogen (N) content was also observed. However, ATP-sulfurylase (ATP-S; EC. 2.7.7.4) activity, sulfur (S) content and activities of antioxidant enzymes such as superoxide dismutase (SOD; E.C. 1.15.1.1); catalase (CAT; E.C. 1.11.1.6); ascorbate peroxidase (APX; E.C. 1.11.1.11) and glutathione reductase (GR; E.C. 1.6.4.2) and glutathione (GSH) content were increased. Specifically, the decrease in NR activity and N content showed that Cd affects N metabolism negatively; whereas, the increase in ATP-S activity and S content suggests the up-regulation of S assimilation pathway for possible Cd tolerance in coordination with enhanced activities of antioxidant enzymes and GSH. High Cd concentration (100mg Cd kg(-1) soil) perturbs the L. sativum growth by interfering with the photosynthetic machinery and disrupting the coordination between carbon, N and S metabolism. On the other hand, at low Cd concentration (25mg Cd kg(-1) soil) co-ordination of S and N

  12. Sulfate resupply accentuates protein synthesis in coordination with nitrogen metabolism in sulfur deprived Brassica napus.

    PubMed

    Zhang, Qian; Lee, Bok-Rye; Park, Sang-Hyun; Zaman, Rashed; Avice, Jean-Christophe; Ourry, Alain; Kim, Tae-Hwan

    2015-02-01

    To investigate the regulatory interactions between S assimilation and N metabolism in Brassica napus, de novo synthesis of amino acids and proteins was quantified by (15)N and (34)S tracing, and the responses of transporter genes, assimilatory enzymes and metabolites pool involving in nitrate and sulfate metabolism were assessed under continuous sulfur supply, sulfur deprivation and sulfate resupply after 3 days of sulfur (S) deprivation. S-deprived plants were characterized by a strong induction of sulfate transporter genes, ATP sulfurylase (ATPS) and adenosine 5'-phosphosulfate reductase (APR), and by a repressed activity of nitrate reductase (NR) and glutamine synthetase (GS). Sulfate resupply to the S-deprived plants strongly increased cysteine, amino acids and proteins concentration. The increase in sulfate and cysteine concentration caused by sulfate resupply was not matched with the expression of sulfate transporters and the activity of ATPS and APR which were rapidly decreased by sulfate resupply. A strong induction of O-acetylserine(thiol)lyase (OASTL), NR and GS upon sulfate resupply was accompanied with the increase in cysteine, amino acids and proteins pool. Sulfate resupply resulted in a strong increase in de novo synthesis of amino acids and proteins, as evidenced by the increases in N and S incorporation into amino acids (1.8- and 2.4-fold increase) and proteins (2.2-and 6.3-fold increase) when compared to S-deprived plants. The results thus indicate that sulfate resupply followed by S-deprivation accelerates nitrate assimilation for protein synthesis.

  13. Spatiotemporal variations and factors affecting soil nitrogen in the purple hilly area of Southwest China during the 1980s and the 2010s.

    PubMed

    Li, Qiquan; Luo, Youlin; Wang, Changquan; Li, Bing; Zhang, Xin; Yuan, Dagang; Gao, Xuesong; Zhang, Hao

    2016-03-15

    Determination of soil nitrogen distributions and the factors affecting them is critical for nitrogen fertilizer management and prevention of nitrogen pollution. In this paper, the spatiotemporal variations of soil nitrogen and the relative importance of their affecting factors were analysed at a county scale in the purple hilly area of the mid-Sichuan Basin in Southwest China based on soil data collected in 1981 and 2012. Statistical results showed that soil total nitrogen (TN) increased from 0.88 g kg(-1) in 1981 to 1.12 g kg(-1) in 2012, whereas available nitrogen (AN) decreased from 84.22 mg kg(-1) to 74.35 mg kg(-1). In particular, AN showed a significant decrease in agricultural ecosystems but remained stable in woodland and grassland. Correspondingly, most of the study area exhibited increased TN content and decreased AN content in space. The nugget/sill ratios of TN and AN increased from 0.419 to 0.608 and from 0.733 to 0.790, whereas spatial correlation distances decreased from 12.00 km to 9.50 km and from 9.50 km to 9.00 km, respectively, suggesting that the spatial dependence of soil nitrogen became weaker and that the extrinsic factors played increasingly important roles in affecting the soil nitrogen distribution. Soil group and land use type were the two dominant factors in 1981, followed by topographic factors, vegetation coverage and parent material, whereas land use type became the most important factor in 2012, and the relative contribution of topographic factors declined markedly. The results suggested that land use related to cultivation management and fertilizer application was the decisive factor for soil nitrogen change. The increase in TN content and the decrease in AN content over the study period also suggested improper use of nitrogen fertilizer, which can result in nitrogen loss through increasing nitrification rates. Thus, effective measures should be taken to increase the uptake rate of nitrogen and prevent nitrogen pollution.

  14. Effects of high CO2 on growth and metabolism of Arabidopsis seedlings during growth with a constantly limited supply of nitrogen.

    PubMed

    Takatani, Nobuyuki; Ito, Takuro; Kiba, Takatoshi; Mori, Marie; Miyamoto, Tetsuro; Maeda, Shin-Ichi; Omata, Tatsuo

    2014-02-01

    Elevated CO2 has been reported to stimulate plant growth under nitrogen-sufficient conditions, but the effects of CO2 on growth in a constantly nitrogen-limited state, which is relevant to most natural habitats of plants, remain unclear. Here, we maintained Arabidopsis seedlings under such conditions by growing a mutant with reduced nitrate uptake activity on a medium containing nitrate as the sole nitrogen source. Under nitrogen-sufficient conditions (i.e. in the presence of ammonium), growth of shoots and roots of both the wild type (WT) and the mutant was increased approximately 2-fold by elevated CO2. Growth stimulation of shoots and roots by elevated CO2 was observed in the WT growing with nitrate as the sole nitrogen source, but in the mutant grown with nitrate, the high-CO2 conditions stimulated only the growth of roots. In the mutant, elevated CO2 caused well-known symptoms of nitrogen-starved plants, including decreased shoot/root ratio, reduced nitrate content and accumulation of anthocyanin, but also had an increased Chl content in the shoot, which was contradictory to the known effect of nitrogen depletion. A high-CO2-responsive change specific to the mutant was not observed in the levels of the major metabolites, although CO2 responses were observed in the WT and the mutant. These results indicated that elevated CO2 causes nitrogen limitation in the seedlings grown with a constantly limited supply of nitrogen, but the Chl content and the root biomass of the plant increase to enhance the activities of both photosynthesis and nitrogen uptake, while maintaining normal metabolism and response to high CO2.

  15. Soluble carbohydrate allocation to roots, photosynthetic rate of leaves, and nitrate assimilation as affected by nitrogen stress and irradiance

    NASA Technical Reports Server (NTRS)

    Henry, L. T.; Raper, C. D. Jr

    1991-01-01

    Upon resupply of exogenous nitrogen to nitrogen-stressed plants, uptake rate of nitrogen is enhanced relative to nonstressed plants. Absorption of nitrogen presumably is dependent on availability of carbohydrates in the roots. A buildup in soluble carbohydrates thus should occur in roots of nitrogen-stressed plants, and upon resupply of exogenous nitrogen the increased uptake rate should be accompanied by a rapid decline in carbohydrates to prestress levels. To evaluate this relationship, three sets of tobacco plants growing in a complete hydroponic solution containing 1.0 mM NO3- were either continued in the complete solution for 21 d, transferred to a minus-nitrogen solution for 21 d, or transferred to a minus-nitrogen solution for 8-9 d and then returned to the 1.0 mM NO3- solution. These nitrogen treatments were imposed upon plants growing at photosynthetic photon flux densities of 700 and 350 micromoles m-2 s-1. Soluble carbohydrate levels in roots increased during onset of nitrogen stress to levels that were fourfold greater than in roots of non-stressed plants. Following resupply of external nitrogen, a rapid resumption of nitrogen uptake was accompanied by a decline in soluble carbohydrates in roots to levels characteristic of nonstressed plants. This pattern of soluble carbohydrate levels in roots during onset of and recovery from nitrogen stress occurred at both irradiance levels. The response of net photosynthetic rate to nitrogen stress could be expressed as a nonlinear function of concentration of reduced nitrogen in leaves. The net photosynthetic rate at a given concentration of reduced nitrogen, however, averaged 10% less at the lower than at the higher irradiance. The decline in net photosynthetic rate per unit of reduced nitrogen in leaves at the lower irradiance was accompanied by an increase in the nitrate fraction of total nitrogen in leaves from 20% at the higher irradiance to 38% at the lower irradiance.

  16. Effect of sulphur deprivation on osmotic potential components and nitrogen metabolism in oilseed rape leaves: identification of a new early indicator.

    PubMed

    Sorin, Elise; Etienne, Philippe; Maillard, Anne; Zamarreño, Angel-Mari; Garcia-Mina, José-Maria; Arkoun, Mustapha; Jamois, Frank; Cruz, Florence; Yvin, Jean-Claude; Ourry, Alain

    2015-10-01

    Identification of early sulphur (S) deficiency indicators is important for species such as Brassica napus, an S-demanding crop in which yield and the nutritional quality of seeds are negatively affected by S deficiency. Because S is mostly stored as SO4 (2-) in leaf cell vacuoles and can be mobilized during S deficiency, this study investigated the impact of S deprivation on leaf osmotic potential in order to identify compensation processes. Plants were exposed for 28 days to S or to chlorine deprivation in order to differentiate osmotic and metabolic responses. While chlorine deprivation had no significant effects on growth, osmotic potential and nitrogen metabolism, Brassica napus revealed two response periods to S deprivation. The first one occurred during the first 13 days during which plant growth was maintained as a result of vacuolar SO4 (2-) mobilization. In the meantime, leaf osmotic potential of S-deprived plants remained similar to control plants despite a reduction in the SO4 (2-) osmotic contribution, which was fully compensated by an increase in NO3 (-), PO4 (3-) and Cl(-) accumulation. The second response occurred after 13 days of S deprivation with a significant reduction in growth, leaf osmotic potential, NO3 (-) uptake and NO3 (-) reductase activity, whereas amino acids and NO3 (-) were accumulated. This kinetic analysis of S deprivation suggested that a ([Cl(-)]+[NO3 (-)]+[PO4 (3-)]):[SO4 (2-)] ratio could provide a relevant indicator of S deficiency, modified nearly as early as the over-expression of genes encoding SO4 (2-) tonoplastic or plasmalemmal transporters, with the added advantage that it can be easily quantified under field conditions.

  17. Drought effects on carbon and nitrogen metabolism of pea nodules can be mimicked by paraquat: evidence for the occurrence of two regulation pathways under oxidative stresses.

    PubMed

    Marino, Daniel; González, Esther M; Arrese-Igor, Cesar

    2006-01-01

    Biological nitrogen fixation (BNF) is dramatically affected by environmental constraints such as water stress or heavy metals. It has been reported that these stresses induce the over-production of reactive oxygen species (ROS) and, in turn, oxidative stress that may be responsible for the above-mentioned BNF decline at the molecular level. Oxidative stress, occurring under different environmental stresses, has been widely related to physiological damage. However, a direct relationship between oxidative stress and the decline of BNF, independently from any other cellular damage resulting from adverse environmental situations, has yet to be demonstrated. In order to study the likely in vivo relationship between ROS and BNF inhibition in the legume-Rhizobium symbiosis, two paraquat (PQ) doses, 1 (LPQ) and 10 (HPQ) mmol m(-3), were applied to pea roots for 96 h in order to exacerbate ROS production. Whole-plant physiology and nodule metabolism parameters were determined every 24 h to monitor the evolution of plant responses to ROS. LPQ provoked BNF decline, which was preceded by a prior decrease in sucrose synthase (SS) activity. However, HPQ gave rise to a faster and more pronounced BNF inhibition, which coincided with a decline in SS and also with a reduction in leghaemoglobin (Lb) content. These results indicate a likely involvement of ROS in the effects of environmental stresses on BNF. Furthermore, these results support the occurrence of two regulation pathways for BNF under oxidative stress, one of these involving carbon shortage and the other involving Lb/oxygen flux.

  18. Modulation of Glycosaminoglycans Affects PrPSc Metabolism but Does Not Block PrPSc Uptake

    PubMed Central

    Wolf, Hanna; Graßmann, Andrea; Bester, Romina; Hossinger, André; Möhl, Christoph; Paulsen, Lydia; Groschup, Martin H.; Schätzl, Hermann

    2015-01-01

    ABSTRACT Mammalian prions are unconventional infectious agents composed primarily of the misfolded aggregated host prion protein PrP, termed PrPSc. Prions propagate by the recruitment and conformational conversion of cellular prion protein into abnormal prion aggregates on the cell surface or along the endocytic pathway. Cellular glycosaminoglycans have been implicated as the first attachment sites for prions and cofactors for cellular prion replication. Glycosaminoglycan mimetics and obstruction of glycosaminoglycan sulfation affect prion replication, but the inhibitory effects on different strains and different stages of the cell infection have not been thoroughly addressed. We examined the effects of a glycosaminoglycan mimetic and undersulfation on cellular prion protein metabolism, prion uptake, and the establishment of productive infections in L929 cells by two mouse-adapted prion strains. Surprisingly, both treatments reduced endogenous sulfated glycosaminoglycans but had divergent effects on cellular PrP levels. Chemical or genetic manipulation of glycosaminoglycans did not prevent PrPSc uptake, arguing against their roles as essential prion attachment sites. However, both treatments effectively antagonized de novo prion infection independently of the prion strain and reduced PrPSc formation in chronically infected cells. Our results demonstrate that sulfated glycosaminoglycans are dispensable for prion internalization but play a pivotal role in persistently maintained PrPSc formation independent of the prion strain. IMPORTANCE Recently, glycosaminoglycans (GAGs) became the focus of neurodegenerative disease research as general attachment sites for cell invasion by pathogenic protein aggregates. GAGs influence amyloid formation in vitro. GAGs are also found in intra- and extracellular amyloid deposits. In light of the essential role GAGs play in proteinopathies, understanding the effects of GAGs on protein aggregation and aggregate dissemination is crucial

  19. Parameters of Glucose and Lipid Metabolism Affect the Occurrence of Colorectal Adenomas Detected by Surveillance Colonoscopies

    PubMed Central

    Kim, Nam Hee; Suh, Jung Yul; Park, Jung Ho; Park, Dong Il; Cho, Yong Kyun; Sohn, Chong Il; Choi, Kyuyong

    2017-01-01

    Purpose Limited data are available regarding the associations between parameters of glucose and lipid metabolism and the occurrence of metachronous adenomas. We investigated whether these parameters affect the occurrence of adenomas detected on surveillance colonoscopy. Materials and Methods This longitudinal study was performed on 5289 subjects who underwent follow-up colonoscopy between 2012 and 2013 among 62171 asymptomatic subjects who underwent an initial colonoscopy for a health check-up between 2010 and 2011. The risk of adenoma occurrence was assessed using Cox proportional hazards modeling. Results The mean interval between the initial and follow-up colonoscopy was 2.2±0.6 years. The occurrence of adenomas detected by the follow-up colonoscopy increased linearly with the increasing quartiles of fasting glucose, hemoglobin A1c (HbA1c), insulin, homeostasis model assessment of insulin resistance (HOMA-IR), and triglycerides measured at the initial colonoscopy. These associations persisted after adjusting for confounding factors. The adjusted hazard ratios for adenoma occurrence comparing the fourth with the first quartiles of fasting glucose, HbA1c, insulin, HOMA-IR, and triglycerides were 1.50 [95% confidence interval (CI), 1.26–1.77; ptrend<0.001], 1.22 (95% CI, 1.04–1.43; ptrend=0.024), 1.22 (95% CI, 1.02–1.46; ptrend=0.046), 1.36 (95% CI, 1.14–1.63; ptrend=0.004), and 1.19 (95% CI, 0.99–1.42; ptrend=0.041), respectively. In addition, increasing quartiles of low-density lipoprotein-cholesterol and apolipoprotein B were associated with an increasing occurrence of adenomas. Conclusion The levels of parameters of glucose and lipid metabolism were significantly associated with the occurrence of adenomas detected on surveillance colonoscopy. Improving the parameters of glucose and lipid metabolism through lifestyle changes or medications may be helpful in preventing metachronous adenomas. PMID:28120565

  20. Nitrogen Metabolism and Growth Enhancement in Tomato Plants Challenged with Trichoderma harzianum Expressing the Aspergillus nidulans Acetamidase amdS Gene.

    PubMed

    Domínguez, Sara; Rubio, M Belén; Cardoza, Rosa E; Gutiérrez, Santiago; Nicolás, Carlos; Bettiol, Wagner; Hermosa, Rosa; Monte, Enrique

    2016-01-01

    Trichoderma is a fungal genus that includes species that are currently being used as biological control agents and/or as biofertilizers. In addition to the direct application of Trichoderma spp. as biocontrol agents in plant protection, recent studies have focused on the beneficial responses exerted on plants, stimulating the growth, activating the defenses, and/or improving nutrient uptake. The amdS gene, encoding an acetamidase of Aspergillus, has been used as a selectable marker for the transformation of filamentous fungi, including Trichoderma spp., but the physiological effects of the introduction of this gene into the genome of these microorganisms still remains unexplored. No evidence of amdS orthologous genes has been detected within the Trichoderma spp. genomes and the amdS heterologous expression in Trichoderma harzianum T34 did not affect the growth of this fungus in media lacking acetamide. However, it did confer the ability for the fungus to use this amide as a nitrogen source. Although a similar antagonistic behavior was observed for T34 and amdS transformants in dual cultures against Rhizoctonia solani, Botrytis cinerea, and Fusarium oxysporum, a significantly higher antifungal activity was detected in amdS transformants against F. oxysporum, compared to that of T34, in membrane assays on media lacking acetamide. In Trichoderma-tomato interaction assays, amdS transformants were able to promote plant growth to a greater extent than the wild-type T34, although compared with this strain the transformants showed similar capability to colonize tomato roots. Gene expression patterns from aerial parts of 3-week-old tomato plants treated with T34 and the amdS transformants have also been investigated using GeneChip Tomato Genome Arrays. The downregulation of defense genes and the upregulation of carbon and nitrogen metabolism genes observed in the microarrays were accompanied by (i) enhanced growth, (ii) increased carbon and nitrogen levels, and (iii) a

  1. Nitrogen Metabolism and Growth Enhancement in Tomato Plants Challenged with Trichoderma harzianum Expressing the Aspergillus nidulans Acetamidase amdS Gene

    PubMed Central

    Domínguez, Sara; Rubio, M. Belén; Cardoza, Rosa E.; Gutiérrez, Santiago; Nicolás, Carlos; Bettiol, Wagner; Hermosa, Rosa; Monte, Enrique

    2016-01-01

    Trichoderma is a fungal genus that includes species that are currently being used as biological control agents and/or as biofertilizers. In addition to the direct application of Trichoderma spp. as biocontrol agents in plant protection, recent studies have focused on the beneficial responses exerted on plants, stimulating the growth, activating the defenses, and/or improving nutrient uptake. The amdS gene, encoding an acetamidase of Aspergillus, has been used as a selectable marker for the transformation of filamentous fungi, including Trichoderma spp., but the physiological effects of the introduction of this gene into the genome of these microorganisms still remains unexplored. No evidence of amdS orthologous genes has been detected within the Trichoderma spp. genomes and the amdS heterologous expression in Trichoderma harzianum T34 did not affect the growth of this fungus in media lacking acetamide. However, it did confer the ability for the fungus to use this amide as a nitrogen source. Although a similar antagonistic behavior was observed for T34 and amdS transformants in dual cultures against Rhizoctonia solani, Botrytis cinerea, and Fusarium oxysporum, a significantly higher antifungal activity was detected in amdS transformants against F. oxysporum, compared to that of T34, in membrane assays on media lacking acetamide. In Trichoderma-tomato interaction assays, amdS transformants were able to promote plant growth to a greater extent than the wild-type T34, although compared with this strain the transformants showed similar capability to colonize tomato roots. Gene expression patterns from aerial parts of 3-week-old tomato plants treated with T34 and the amdS transformants have also been investigated using GeneChip Tomato Genome Arrays. The downregulation of defense genes and the upregulation of carbon and nitrogen metabolism genes observed in the microarrays were accompanied by (i) enhanced growth, (ii) increased carbon and nitrogen levels, and (iii) a

  2. Increased iron availability resulting from increased CO2 enhances carbon and nitrogen metabolism in the economical marine red macroalga Pyropia haitanensis (Rhodophyta).

    PubMed

    Chen, Binbin; Zou, Dinghui; Yang, Yufeng

    2017-04-01

    Ocean acidification caused by rising CO2 is predicted to increase the concentrations of dissolved species of Fe(II) and Fe(III), leading to the enhanced photosynthetic carbon sequestration in some algal species. In this study, the carbon and nitrogen metabolism in responses to increased iron availability under two CO2 levels (390 μL L(-1) and 1000 μL L(-1)), were investigated in the maricultivated macroalga Pyropia haitanensis (Rhodophyta). The results showed that, elevated CO2 increased soluble carbonhydrate (SC) contents, resulting from enhanced photosynthesis and photosynthetic pigment synthesis in this algae, but declined its soluble protein (SP) contents, resulting in increased ratio of SC/SP. This enhanced photosynthesis performance and carbon accumulation was more significant under iron enrichment condition in seawater, with higher iron uptake rate at high CO2 level. As a key essential biogenic element for algae, Fe-replete functionally contributed to P. haitanensis photosynthesis. Increased SC fundamentally provided carbon skeletons for nitrogen assimilation. The significant increase of carbon and nitrogen assimilation finally contributed to enhanced growth in this alga. This was also intuitively reflected by respiration that provided energy for cellular metabolism and algal growth. We propose that, in the predicted scenario of rising atmospheric CO2, P. haitanensis is capable to adjust its physiology by increasing its carbon and nitrogen metabolism to acclimate the acidified seawater, at the background of global climate change and simultaneously increased iron concentration due to decreased pH levels.

  3. Modelling Plant and Soil Nitrogen Feedbacks Affecting Forest Carbon Gain at High CO2

    NASA Astrophysics Data System (ADS)

    McMurtrie, R. E.; Norby, R. J.; Franklin, O.; Pepper, D. A.

    2007-12-01

    Short-term, direct effects of elevated atmospheric CO2 concentrations on plant carbon gain are relatively well understood. There is considerable uncertainty, however, about longer-term effects, which are influenced by various plant and ecosystem feedbacks. A key feedback in terrestrial ecosystems occurs through changes in plant carbon (C) allocation patterns. For instance, if high CO2 were to increase C allocation to roots, then plants may experience positive feedback through improved plant nutrition. A second type of feedback, associated with decomposition of soil-organic matter, may reduce soil-nutrient availability at high CO2. This paper will consider mechanistic models of both feedbacks. Effects of high CO2 on plant C allocation will be investigated using a simple model of forest net primary production (NPP) that incorporates the primary mechanisms of plant carbon and nitrogen (N) balance. The model called MATE (Model Any Terrestrial Ecosystem) includes an equation for annual C balance that depends on light- saturated photosynthetic rate and therefore on [CO2], and an equation for N balance incorporating an expression for N uptake as a function of root mass. The C-N model is applied to a Free Air CO2 Exchange (FACE) experiment at Oak Ridge National Laboratory (ORNL) in Tennessee, USA, where closed-canopy, monoculture stands of the deciduous hardwood sweetgum ( Liquidambar styraciflua) have been growing at [CO2] of 375 and 550 ppm for ten years. Features of this experiment are that the annual NPP response to elevated CO2 has averaged approximately 25% over seven years, but that annual fine-root production has almost doubled on average, with especially large increases in later years of the experiment (Norby et al. 2006). The model provides a simple graphical approach for analysing effects of elevated CO2 and N supply on leaf/root/wood C allocation and productivity. It simulates increases in NPP and fine-root production at the ORNL FACE site that are consistent

  4. Carbon and nitrogen tracers of land use effects on net ecosystem metabolism in mangrove estuaries, southwest Florida

    NASA Astrophysics Data System (ADS)

    Dvorak, Matthew; Mora, Germán; Graniero, Lauren; Surge, Donna

    2016-11-01

    Four estuaries in southwest Florida with different land-use characteristics in their watersheds were chosen to investigate the effects of anthropogenic land use on estuarine biogeochemical cycling. We compared C:N ratios, concentrations of dissolved inorganic carbon (DIC), chlorophyll-a (chl-a) and particulate organic carbon (POC), stable isotope ratios of DIC (δ13CDIC) and POC (δ13CPOC), and nitrogen isotope ratios of particulate organic nitrogen (δ15NPON) among these estuaries. Values of δ13CDIC ranged from -14.1 to +0.9‰. The more negative values occurred upstream, resulting from DIC inputs derived from both the degradation of organic carbon and dissolution of carbonates. Upstream DIC concentrations were as high as 8066 μmol L-1, suggesting high respiration rates. Further, a comparison of DIC values to a conservative mixing model indicates net heterotrophic metabolic state in all four estuaries. Supporting this interpretation, low δ13CPOC values suggest that terrestrial plants were the main source of POC in the upstream sampling points. However, C:N ratios ranged from 7.2 to 13.4, and were consistent with the decomposition of both terrestrial and aquatic sources. Chl-a concentrations were variable and typically below 20 μg L-1, indicating moderate to low levels of autotrophy in all estuaries. Elevated chl-a concentrations indicative of increased primary productivity occurred at intermediate salinities, and were possibly caused by the mixing front at mid-estuary locations. There were no apparent differences in δ15NPON among estuaries, suggesting that the N sources to these estuaries are comparable. The combined results show no differences between near-natural and anthropogenically influenced estuaries, indicating a minimal effect of anthropogenic activities on the parameters measured, possibly as a result of the filtering capacity of the extensive surrounding mangrove vegetation.

  5. Are carbon and nitrogen exchange between fungi and the orchid Goodyera repens affected by irradiance?

    PubMed Central

    Liebel, Heiko T.; Bidartondo, Martin I.; Gebauer, Gerhard

    2015-01-01

    Background and Aims The green orchid Goodyera repens has been shown to transfer carbon to its mycorrhizal partner, and this flux may therefore be affected by light availability. This study aimed to test whether the C and N exchange between plant and fungus is dependent on light availability, and in addition addressed the question of whether flowering and/or fruiting individuals of G. repens compensate for changes in leaf chlorophyll concentration with changes in C and N flows from fungus to plant. Methods The natural abundances of stable isotopes of plant C and N were used to infer changes in fluxes between orchid and fungus across natural gradients of irradiance at five sites. Mycorrhizal fungi in the roots of G. repens were identified by molecular analyses. Chlorophyll concentrations in the leaves of the orchid and of reference plants were measured directly in the field. Key Results Leaf δ13C values of G. repens responded to changes in light availability in a similar manner to autotrophic reference plants, and different mycorrhizal fungal associations also did not affect the isotope abundance patterns of the orchid. Flowering/fruiting individuals had lower leaf total N and chlorophyll concentrations, which is most probably explained by N investments to form flowers, seeds and shoot. Conclusions The results indicate that mycorrhizal physiology is relatively fixed in G. repens, and changes in the amount and direction of C flow between plant and fungus were not observed to depend on light availability. The orchid may instead react to low-light sites through increased clonal growth. The orchid does not compensate for low leaf total N and chlorophyll concentrations by using a 13C- and 15N-enriched fungal source. PMID:25538109

  6. Low protein provision during the first year of life, but not during foetal life, affects metabolic traits, organ mass development and growth in male mink (Neovison vison).

    PubMed

    Vesterdorf, K; Blache, D; Harrison, A; Matthiesen, C F; Tauson, A-H

    2014-04-01

    Low protein provision in utero and post-partum may induce metabolic disorders in adulthood. Studies in mink have mainly focused on short-term consequences of low protein provision in utero whereas the long-term responses to low protein (LP) provision in metabolically programmed mink are unknown. We investigated whether low protein provision in utero affects the long-term response to adequate (AP) or LP provision after weaning in male mink. Eighty-six male mink were exposed to low (19% of ME from CP; crude protein) or adequate (31% of ME from CP) protein provision in utero, and to LP (~20% of ME from CP) or AP (30-42% of ME from CP) provision post-weaning. Being metabolically programmed by low protein provision in utero did not affect the response to post-weaning diets. Dietary protein content in the LP feed after weaning was below requirements; evidenced by lower nitrogen retention (p < 0.001) preventing LP mink from attaining their growth potential (p < 0.02). LP mink had a lower liver, pancreas and kidney weight (p < 0.05) as well as lower plasma IGF-1 concentrations at 8 and 25 (p < 0.05) weeks, and a higher incidence of hepatic lipidosis at 25 weeks (p < 0.05). Furthermore, LP mink had a higher body fat (p < 0.05) and lower body CP content (p < 0.05) at 50 weeks of age. It is concluded that some effects of low protein provision in utero can be alleviated by an adequate nutrient supply post-partum. However, long-term exposure to low protein provision in mink reduces their growth potential and induces transient hepatic lipidosis and modified body composition.

  7. Genome Analysis Coupled with Physiological Studies Reveals a Diverse Nitrogen Metabolism in Methylocystis sp. Strain SC2

    PubMed Central

    Blom, Jochen; Liesack, Werner

    2013-01-01

    Background Methylocystis sp. strain SC2 can adapt to a wide range of methane concentrations. This is due to the presence of two isozymes of particulate methane monooxygenase exhibiting different methane oxidation kinetics. To gain insight into the underlying genetic information, its genome was sequenced and found to comprise a 3.77 Mb chromosome and two large plasmids. Principal Findings We report important features of the strain SC2 genome. Its sequence is compared with those of seven other methanotroph genomes, comprising members of the Alphaproteobacteria, Gammaproteobacteria, and Verrucomicrobia. While the pan-genome of all eight methanotroph genomes totals 19,358 CDS, only 154 CDS are shared. The number of core genes increased with phylogenetic relatedness: 328 CDS for proteobacterial methanotrophs and 1,853 CDS for the three alphaproteobacterial Methylocystaceae members, Methylocystis sp. strain SC2 and strain Rockwell, and Methylosinus trichosporium OB3b. The comparative study was coupled with physiological experiments to verify that strain SC2 has diverse nitrogen metabolism capabilities. In correspondence to a full complement of 34 genes involved in N2 fixation, strain SC2 was found to grow with atmospheric N2 as the sole nitrogen source, preferably at low oxygen concentrations. Denitrification-mediated accumulation of 0.7 nmol 30N2/hr/mg dry weight of cells under anoxic conditions was detected by tracer analysis. N2 production is related to the activities of plasmid-borne nitric oxide and nitrous oxide reductases. Conclusions/Perspectives Presence of a complete denitrification pathway in strain SC2, including the plasmid-encoded nosRZDFYX operon, is unique among known methanotrophs. However, the exact ecophysiological role of this pathway still needs to be elucidated. Detoxification of toxic nitrogen compounds and energy conservation under oxygen-limiting conditions are among the possible roles. Relevant features that may stimulate further research are

  8. Nitrogen metabolism responses to water deficit act through both abscisic acid (ABA)-dependent and independent pathways in Medicago truncatula during post-germination.

    PubMed

    Planchet, Elisabeth; Rannou, Olivier; Ricoult, Claudie; Boutet-Mercey, Stéphanie; Maia-Grondard, Alessandra; Limami, Anis M

    2011-01-01

    The modulation of primary nitrogen metabolism by water deficit through ABA-dependent and ABA-independent pathways was investigated in the model legume Medicago truncatula. Growth and glutamate metabolism were followed in young seedlings growing for short periods in darkness and submitted to a moderate water deficit (simulated by polyethylene glycol; PEG) or treated with ABA. Water deficit induced an ABA accumulation, a reduction of axis length in an ABA-dependent manner, and an inhibition of water uptake/retention in an ABA-independent manner. The PEG-induced accumulation of free amino acids (AA), principally asparagine and proline, was mimicked by exogenous ABA treatment. This suggests that AA accumulation under water deficit may be an ABA-induced osmolyte accumulation contributing to osmotic adjustment. Alternatively, this accumulation could be just a consequence of a decreased nitrogen demand caused by reduced extension, which was triggered by water deficit and exogenous ABA treatment. Several enzyme activities involved in glutamate metabolism and genes encoding cytosolic glutamine synthetase (GS1b; EC 6.3.1.2.), glutamate dehydrogenase (GDH3; EC 1.4.1.1.), and asparagine synthetase (AS; EC 6.3.1.1.) were up-regulated by water deficit but not by ABA, except for a gene encoding Δ(1)-pyrroline-5-carboxylate synthetase (P5CS; EC not assigned). Thus, ABA-dependent and ABA-independent regulatory systems would seem to exist, differentially controlling development, water content, and nitrogen metabolism under water deficit.

  9. Does temperature of charcoal creation affect subsequent mineralization of soil carbon and nitrogen?

    NASA Astrophysics Data System (ADS)

    Pelletier-Bergeron, S.; Bradley, R.; Munson, A. D.

    2012-04-01

    Forest fire is the most common form of natural disturbance of boreal forest ecosystems and has primordial influence on successional processes. This may be due in part to the pre-disturbance vegetation development stage and species composition, but these successional pathways could also vary with differences in fire behavior and consequently in fire intensity, defined as the energy released during various phases of a fire. Fire intensity may also affect soil C and N cycling by affecting the quality of the charcoal that is produced. For example, the porosity of coal tends to increase with increasing temperature at which it is produced Higher porosity would logically increase the surface area to which dissolved soil molecules, such as tannins and other phenolics, may be adsorbed. We report on a microcosm study in which mineral and organic soils were jointly incubated for eight weeks with a full factorial array of treatments that included the addition of Kalmia tannins, protein, and wood charcoal produced at five different temperatures. A fourth experimental factor comprised the physical arrangement of the material (stratified vs. mixed), designed to simulate the effect of soil scarification after fire and salvage harvest. We examined the effects of these treatments on soil C and N mineralisation and soil microbial biomass. The furnace temperature at which the charcoal was produced had a significant effect on its physico-chemical properties; increasing furnace temperatures corresponded to a significant increase in % C (P<0.001), and a significant decrease in %O (P<0.001) and %H (P<0.001). Temperature also had significant impacts on microporosity (surface area and volume). Temperature of production had no effect (P=0.1355) on soil microbial biomass. We observed a linear decreasing trend (P<0.001) in qCO2 with increasing temperature of production, which was mainly reflected in a decline in basal respiration. Finally, we found a significant interaction (P=0.010) between

  10. The use of nickel to probe the role of hydrogen metabolism in cyanobacterial nitrogen fixation.

    PubMed

    Pederson, D M; Daday, A; Smith, G D

    1986-01-01

    The hydrogenase activities of the heterocystous cyanobacteria Anabaena cylindrica and Mastigocladus laminosus are nickel dependent, based on their inability to consume hydrogen with various electron acceptors or produce hydrogen with dithionite-reduced methyl viologen, after growth in nickel-depleted medium. Upon addition of nickel ions to nickel-deficient cultures of A. cylindrica, the hydrogenase activity recovered in a manner which was protein synthesis-dependent, the recovery being inhibited by chloramphenicol. We have used the nickel dependence of the hydrogenase as a probe of the possible roles of H2 consumption in enhancing nitrogen fixation, and particularly for protecting nitrogenase against oxygen inhibition. Although at the usual growth temperatures (25 degrees for A. cylindrica and 40 degrees for M. laminosus), the cells consume H2 vigorously in an oxyhydrogen reaction after growth in the presence of nickel ions, we have not found that the reaction confers any significant additional protection of nitrogenase, either at aerobic pO2 (for both organisms) or at elevated pO2 (for A. cylindrica). However, at elevated temperatures (e.g., 40 degrees for A. cylindrica and 48 degrees for M. laminosus) a definite protective effect was observed. At these temperatures both organisms rapidly lost acetylene reduction activity under aerobic conditions. When hydrogen gas (10%) was present, the cells retained approximately 50% of the nitrogenase activity observed under anaerobic conditions (argon gas phase). No such protection by hydrogen gas was observed with nickel-deficient cells. Studies with cell-free extracts of A. cylindrica showed that the predominant effect of temperature was not due to thermal inactivation of nitrogenase.

  11. Excretory nitrogen metabolism in the juvenile axolotl Ambystoma mexicanum: differences in aquatic and terrestrial environments.

    PubMed

    Loong, Ai M; Chew, Shit F; Ip, Yuen K

    2002-01-01

    The fully grown but nonmetamorphosed (juvenile) axolotl Ambystoma mexicanum was ureogenic and primarily ureotelic in water. A complete ornithine-urea cycle (OUC) was present in the liver. Aerial exposure impeded urea (but not ammonia) excretion, leading to a decrease in the percentage of nitrogen excreted as urea in the first 24 h. However, urea and not ammonia accumulated in the muscle, liver, and plasma during aerial exposure. By 48 h, the rate of urea excretion recovered fully, probably due to the greater urea concentration gradient in the kidney. It is generally accepted that an increase in carbamoyl phosphate synthetase activity is especially critical in the developmental transition from ammonotelism to ureotelism in the amphibian. Results from this study indicate that such a transition in A. mexicanum would have occurred before migration to land. Aerial exposure for 72 h exhibited no significant effect on carbamoyl phosphate synthetase-I activity or that of other OUC enzymes (with the exception of ornithine transcarbamoylase) from the liver of the juvenile A. mexicanum. This supports our hypothesis that the capacities of OUC enzymes present in the liver of the aquatic juvenile axolotl were adequate to prepare it for its invasion of the terrestrial environment. The high OUC capacity was further supported by the capability of the juvenile A. mexicanum to survive in 10 mM NH(4)Cl without accumulating amino acids in its body. The majority of the accumulating endogenous and exogenous ammonia was detoxified to urea, which led to a greater than twofold increase in urea levels in the muscle, liver, and plasma and a significant increase in urea excretion by hour 96. Hence, it can be concluded that the juvenile axolotl acquired ureotelism while submerged in water, and its hepatic capacity of urea synthesis was more than adequate to handle the toxicity of endogenous ammonia during migration to land.

  12. Signatures of nitrogen limitation in the elemental composition of the proteins involved in the metabolic apparatus.

    PubMed

    Acquisti, Claudia; Kumar, Sudhir; Elser, James J

    2009-07-22

    Nitrogen (N) is a fundamental component of nucleotides and amino acids and is often a limiting nutrient in natural ecosystems. Thus, study of the N content of biomolecules may establish important connections between ecology and genomics. However, while significant differences in the elemental composition of whole organisms are well documented, how the flux of nutrients in the cell has shaped the evolution of different cellular processes remains poorly understood. By examining the elemental composition of major functional classes of proteins in four multicellular eukaryotic model organisms, we find that the catabolic machinery shows substantially lower N content than the anabolic machinery and the rest of the proteome. This pattern suggests that ecological selection for N conservation specifically targets cellular components that are highly expressed in response to nutrient limitation. We propose that the RNA component of the anabolic machineries is the mechanistic force driving the elemental imbalance we found, and that RNA functions as an intracellular nutrient reservoir that is degraded and recycled during starvation periods. A comparison of the elemental composition of the anabolic and catabolic machineries in species that have experienced different levels of N limitation in their evolutionary history (animals versus plants) suggests that selection for N conservation has preferentially targeted the catabolic machineries of plants, resulting in a lower N content of the proteins involved in their catabolic processes. These findings link the composition of major cellular components to the environmental factors that trigger the activation of those components, suggesting that resource availability has constrained the atomic composition and the molecular architecture of the biotic processes that enable cells to respond to reduced nutrient availability.

  13. Waste nitrogen metabolism and excretion in zebrafish embryos: effects of light, ammonia, and nicotinamide.

    PubMed

    Bucking, Carol; Lemoine, Christophe M R; Walsh, Patrick J

    2013-08-01

    Bony fish primarily excrete ammonia as adults however the persistence of urea cycle genes may reflect a beneficial role for urea production during embryonic stages in protecting the embryo from toxic effects of ammonia produced from a highly nitrogenous yolk. This study aimed to examine the dynamic scope for changes in rates of urea synthesis and excretion in one such species (zebrafish, Danio rerio) by manipulating the intrinsic developmental rate (by alteration of light:dark cycles), as well as by direct chemical manipulation via ammonia injection (to potentially activate urea production) and nicotinamide exposure (to potentially inhibit urea production). Continuous dark exposure delayed development in embryos as evidenced by delayed appearance of hallmark anatomical features (heartbeat, eye pigmentation, body pigmentation, lateral line, fin buds) at 30 and 48 hr post-fertilization, as well by a lower hatching rate compared to embryos reared in continuous light. Both ammonia and urea excretion were similarly effected and were generally higher in embryos continuously exposed to light. Ammonia injection resulted in significant increases (up to fourfold) of urea N excretion and no changes to ammonia excretion rates along with modest increases in yolk ammonia content during 2-6 hr post-injection. Nicotinamide (an inhibitor of urea synthesis in mammals) reduced the ammonia-induced increase in urea excretion and led to retention of ammonia in the yolk and body of the embryo. Our results indicate that there is a relatively rapid and large scope for increases in urea production/excretion rates in developing embryos. Potential mechanisms for these increases are discussed.

  14. Metabolic effects of artificial environments

    NASA Technical Reports Server (NTRS)

    Jordan, J. P.

    1973-01-01

    Effects of diluent gases on the metabolism of animals breathing nitrogen-oxygen, argon-oxygen, and helium-oxygen mixtures were studied. Results show that helium actually affected the mean free path of oxygen across the alveoli and increased metabolic rate. It is speculated that it might be necessary to keep an astronaut in a depressed metabolic state during prolonged space flight by using an argon-oxygen or a xenon-nitrogen mixture for breathing. Replacement of the depressant gases during periods requiring critical spacecraft maneuvers by neon-oxygen mixtures would insure maximal performance.

  15. DMPP-added nitrogen fertilizer affects soil N2O emission and microbial activity in Southern Italy

    NASA Astrophysics Data System (ADS)

    Vitale, Luca; De Marco, Anna; Maglione, Giuseppe; Polimeno, Franca; Di Tommasi, Paul; Magliulo, Vincenzo

    2014-05-01

    Arable sites contributes to global N2O emission due to massive utilization of nitrogen fertilizers. N2O derives from the biological processes such as nitrification and denitrification influenced by soil nitrogen availability. The use of nitrogen fertilizers added with nitrification inhibitors represents one among the proposed strategy to reduce soil N2O emission form arable sites. The aim of this work was to evaluate the effects of 3,4-dimethylphyrazole phosphate (DMPP), a nitrification inhibitor, on N2O emission and microbial activity of a soil cropped to potato in Southern Italy. The experiment was a randomized block design with two treatments applied and three replicates: control (C) and DMPP (Entec®, K+S Nitrogen) plots, both supplied with the same amount of ammonium nitrate. The nitrogen fertilizer was supplied in three events: at 0 Day After Sowing (DAS; 100 kg N ha-1), at 57 DAS (30 kg N ha-1), and at 71 DAS (30 kg N ha-1). Soil N2O emission was monitored by both dynamic and static chambers. Static chambers were located both on hills and furrows whereas dynamic chambers were located on furrows. Air samples were collected from chambers at different times and analysed by a gas chromatograph (SRI 8610C, Gas Chromatograph). Fluxes were estimated as a linear interpolation of N2O changes over a 30 min time. Microbial biomass and basal respiration were determined as CO2 evolution, analysed by means of an IRGA (Li6200, Licor), on 2 g of fresh soil over a 4h incubation time. Microbial biomass was determined by Substrate Induced Respiration method. Data show no statistical differences in N2O fluxes measured with either dynamic chambers between C and DMPP plots in studied period. However, after the first fertilization event, when the fertilizer was applied as 100 kg N ha-1, the average N2O fluxes measured with static chambers were higher in DMPP plots compared to C plots. In the same period, the microbial biomass significantly decreased in DMPP plots as compared to C

  16. Nitrogen Redox Metabolism of a Heterotrophic, Nitrifying-Denitrifying Alcaligenes sp. from Soil

    PubMed Central

    Castignetti, Domenic; Hollocher, Thomas C.

    1982-01-01

    Metabolic characteristics of a heterotrophic, nitrifier-denitrifier Alcaligenes sp. isolated from soil were further characterized. Pyruvic oxime and hydroxylamine were oxidized to nitrite aerobically by nitrification-adapted cells with specific activities (Vmax) of 0.066 and 0.003 μmol of N × min−1 × mg of protein−1, respectively, at 22°C. Km values were 15 and 42 μM for pyruvic oxime and hydroxylamine, respectively. The greater pyruvic oxime oxidation activity relative to hydroxylamine oxidation activity indicates that pyruvic oxime was a specific substrate and was not oxidized appreciably via its hydrolysis product, hydroxylamine. When grown as a denitrifier on nitrate, the bacterium could not aerobically oxidize pyruvic oxime or hydroxylamine to nitrite. However, hydroxylamine was converted to nearly equimolar amounts of ammonium ion and nitrous oxide, and the nature of this reaction is discussed. Cells grown as heterotrophic nitrifiers on pyruvic oxime contained two enzymes of denitrification, nitrate reductase and nitric oxide reductase. The nitrate reductase was the dissimilatory type, as evidenced by its extreme sensitivity to inhibition by azide and by its ability to be reversibly inhibited by oxygen. Cells grown aerobically on organic carbon sources other than pyruvic oxime contained none of the denitrifying enzymes surveyed but were able to oxidize pyruvic oxime to nitrite and reduce hydroxylamine to ammonium ion. PMID:16346117

  17. Dietary arginine affects energy metabolism through polyamine turnover in juvenile Atlantic salmon (Salmo salar).

    PubMed

    Andersen, Synne M; Holen, Elisabeth; Aksnes, Anders; Rønnestad, Ivar; Zerrahn, Jens-Erik; Espe, Marit

    2013-12-14

    In the present study, quadruplicate groups of juvenile Atlantic salmon (Salmo salar) were fed plant protein-based diets with increasing arginine inclusions (range 28·8-37·4 g/kg DM) to investigate whether arginine supplementation affects growth and lipid accumulation through an elevated polyamine turnover. Dietary lysine was held at a constant concentration, just below the requirement. All other amino acids were balanced and equal in the diets. Arginine supplementation increased protein and fat accretion, without affecting the hepatosomatic or visceralsomatic indices. Dietary arginine correlated with putrescine in the liver (R 0·78, P= 0·01) and with ornithine in the muscle, liver and plasma (P= 0·0002, 0·003 and 0·0002, respectively). The mRNA of ornithine decarboxylase, the enzyme producing putrescine, was up-regulated in the white adipose tissue of fish fed the high-arginine inclusion compared with those fed the low-arginine diet. Concomitantly, spermidine/spermine-(N1)-acetyltransferase, the rate-limiting enzyme for polyamine turnover that consumes acetyl-CoA, showed an increased activity in the liver of fish fed the arginine-supplemented diets. In addition, lower acetyl-CoA concentrations were observed in the liver of fish fed the high-arginine diet, while ATP, which is used in the process of synthesising spermidine and spermine, did not show a similar trend. Gene expression of the rate-limiting enzyme for β-oxidation of long-chain fatty acids, carnitine palmitoyl transferase-1, was up-regulated in the liver of fish fed the high-arginine diet. Taken together, the data support that increased dietary arginine activates polyamine turnover and β-oxidation in the liver of juvenile Atlantic salmon and may act to improve the metabolic status of the fish.

  18. Argon does not affect cerebral circulation or metabolism in male humans

    PubMed Central

    Kazmaier, Stephan; Hoeks, Sanne Elisabeth; Stolker, Robert Jan; Coburn, Marc; Weyland, Andreas

    2017-01-01

    Objective Accumulating data have recently underlined argon´s neuroprotective potential. However, to the best of our knowledge, no data are available on the cerebrovascular effects of argon (Ar) in humans. We hypothesized that argon inhalation does not affect mean blood flow velocity of the middle cerebral artery (Vmca), cerebral flow index (FI), zero flow pressure (ZFP), effective cerebral perfusion pressure (CPPe), resistance area product (RAP) and the arterio-jugular venous content differences of oxygen (AJVDO2), glucose (AJVDG), and lactate (AJVDL) in anesthetized patients. Materials and methods In a secondary analysis of an earlier controlled cross-over trial we compared parameters of the cerebral circulation under 15 minutes exposure to 70%Ar/30%O2 versus 70%N2/30%O2 in 29 male patients under fentanyl-midazolam anaesthesia before coronary surgery. Vmca was measured by transcranial Doppler sonography. ZFP and RAP were estimated by linear regression analysis of pressure-flow velocity relationships of the middle cerebral artery. CPPe was calculated as the difference between mean arterial pressure and ZFP. AJVDO2, AJVDG and AJVDL were calculated as the differences in contents between arterial and jugular-venous blood of oxygen, glucose, and lactate. Statistical analysis was done by t-tests and ANOVA. Results Mechanical ventilation with 70% Ar did not cause any significant changes in mean arterial pressure, Vmca, FI, ZFP, CPPe, RAP, AJVDO2, AJVDG, and AJVDL. Discussion Short-term inhalation of 70% Ar does not affect global cerebral circulation or metabolism in male humans under general anaesthesia. PMID:28207907

  19. Land-use and hydroperiod affect kettle hole sediment carbon and nitrogen biogeochemistry.

    PubMed

    Nitzsche, Kai Nils; Kalettka, Thomas; Premke, Katrin; Lischeid, Gunnar; Gessler, Arthur; Kayler, Zachary Eric

    2017-01-01

    Kettle holes are glaciofluvially created depressional wetlands that collect organic matter (OM) and nutrients from their surrounding catchment. Kettle holes mostly undergo pronounced wet-dry cycles. Fluctuations in water table, land-use, and management can affect sediment biogeochemical transformations and perhaps threaten the carbon stocks of these unique ecosystems. We investigated sediment and water of 51 kettle holes in NE Germany that differ in hydroperiod (i.e. the duration of the wet period of a kettle hole) and land-use. Our objectives were 1) to test if hydroperiod and land management were imprinted on the isotopic values (δ(13)C, δ(15)N) and C:N ratios of the sediment OM, and 2) to characterize water loss dynamics and kettle hole-groundwater connectivity by measuring the stable δ(18)O and δD isotope values of kettle hole water over several years. We found the uppermost sediment layer reflected recent OM inputs and short-term processes in the catchment, including land-use and management effects. Deeper sediments recorded the degree to which OM is processed within the kettle hole related to the hydroperiod. We see clear indications for the effects of wet-dry cycles for all kettle holes, which can lead to the encroachment of terrestrial plants. We found that the magnitude of evaporation depended on the year, season, and land-use type, that kettle holes are temporarily coupled to shallow ground water, and, as such, kettle holes are described best as partially-closed to open systems.

  20. Alkyl-methylimidazolium ionic liquids affect the growth and fermentative metabolism of Clostridium sp

    SciTech Connect

    Nancharaiah, Y.V.; Francis, A.

    2011-06-01

    In this study, the effect of ionic liquids, 1-ethyl-3-methylimidazolium acetate [EMIM][Ac], 1-ethyl-3-methylimidazolium diethylphosphate [EMIM][DEP], and 1-methyl-3-methylimidazolium dimethylphosphate [MMIM][DMP] on the growth and glucose fermentation of Clostridium sp. was investigated. Among the three ionic liquids tested, [MMIM][DMP] was found to be least toxic. Growth of Clostridium sp. was not inhibited up to 2.5, 4 and 4 g L{sup -1} of [EMIM][Ac], [EMIM][DEP] and [MMIM][DMP], respectively. [EMIM][Ac] at <2.5 g L{sup -1}, showed hormetic effect and stimulated the growth and fermentation by modulating medium pH. Total organic acid production increased in the presence of 2.5 and 2 g L{sup -1} of [EMIM][Ac] and [MMIM][DMP]. Ionic liquids had no significant influence on alcohol production at <2.5 g L{sup -1}. Total gas production was affected by ILs at {ge}2.5 g L{sup -1} and varied with type of methylimidazolium IL. Overall, the results show that the growth and fermentative metabolism of Clostridium sp. is not impacted by ILs at concentrations below 2.5 g L{sup -1}.

  1. Perturbations of amino acid metabolism associated with glyphosate-dependent inhibition of shikimic acid metabolism affect cellular redox homeostasis and alter the abundance of proteins involved in photosynthesis and photorespiration.

    PubMed

    Vivancos, Pedro Diaz; Driscoll, Simon P; Bulman, Christopher A; Ying, Liu; Emami, Kaveh; Treumann, Achim; Mauve, Caroline; Noctor, Graham; Foyer, Christine H

    2011-09-01

    The herbicide glyphosate inhibits the shikimate pathway of the synthesis of amino acids such as phenylalanine, tyrosine, and tryptophan. However, much uncertainty remains concerning precisely how glyphosate kills plants or affects cellular redox homeostasis and related processes in glyphosate-sensitive and glyphosate-resistant crop plants. To address this issue, we performed an integrated study of photosynthesis, leaf proteomes, amino acid profiles, and redox profiles in the glyphosate-sensitive soybean (Glycine max) genotype PAN809 and glyphosate-resistant Roundup Ready Soybean (RRS). RRS leaves accumulated much more glyphosate than the sensitive line but showed relatively few changes in amino acid metabolism. Photosynthesis was unaffected by glyphosate in RRS leaves, but decreased abundance of photosynthesis/photorespiratory pathway proteins was observed together with oxidation of major redox pools. While treatment of a sensitive genotype with glyphosate rapidly inhibited photosynthesis and triggered the appearance of a nitrogen-rich amino acid profile, there was no evidence of oxidation of the redox pools. There was, however, an increase in starvation-associated and defense proteins. We conclude that glyphosate-dependent inhibition of soybean leaf metabolism leads to the induction of defense proteins without sustained oxidation. Conversely, the accumulation of high levels of glyphosate in RRS enhances cellular oxidation, possibly through mechanisms involving stimulation of the photorespiratory pathway.

  2. Perturbations of Amino Acid Metabolism Associated with Glyphosate-Dependent Inhibition of Shikimic Acid Metabolism Affect Cellular Redox Homeostasis and Alter the Abundance of Proteins Involved in Photosynthesis and Photorespiration1[W][OA

    PubMed Central

    Vivancos, Pedro Diaz; Driscoll, Simon P.; Bulman, Christopher A.; Ying, Liu; Emami, Kaveh; Treumann, Achim; Mauve, Caroline; Noctor, Graham; Foyer, Christine H.

    2011-01-01

    The herbicide glyphosate inhibits the shikimate pathway of the synthesis of amino acids such as phenylalanine, tyrosine, and tryptophan. However, much uncertainty remains concerning precisely how glyphosate kills plants or affects cellular redox homeostasis and related processes in glyphosate-sensitive and glyphosate-resistant crop plants. To address this issue, we performed an integrated study of photosynthesis, leaf proteomes, amino acid profiles, and redox profiles in the glyphosate-sensitive soybean (Glycine max) genotype PAN809 and glyphosate-resistant Roundup Ready Soybean (RRS). RRS leaves accumulated much more glyphosate than the sensitive line but showed relatively few changes in amino acid metabolism. Photosynthesis was unaffected by glyphosate in RRS leaves, but decreased abundance of photosynthesis/photorespiratory pathway proteins was observed together with oxidation of major redox pools. While treatment of a sensitive genotype with glyphosate rapidly inhibited photosynthesis and triggered the appearance of a nitrogen-rich amino acid profile, there was no evidence of oxidation of the redox pools. There was, however, an increase in starvation-associated and defense proteins. We conclude that glyphosate-dependent inhibition of soybean leaf metabolism leads to the induction of defense proteins without sustained oxidation. Conversely, the accumulation of high levels of glyphosate in RRS enhances cellular oxidation, possibly through mechanisms involving stimulation of the photorespiratory pathway. PMID:21757634

  3. Central Role of Glutamate Metabolism in the Maintenance of Nitrogen Homeostasis in Normal and Hyperammonemic Brain

    PubMed Central

    Cooper, Arthur J. L.; Jeitner, Thomas M.

    2016-01-01

    carboxylase. Here, we suggest that glutamate may constitute a buffer or bulwark against changes in cerebral amine and ammonia nitrogen. Although the glutamate transporters are briefly discussed, the major emphasis of the present review is on the enzymology contributing to the maintenance of glutamate levels under normal and hyperammonemic conditions. Emphasis will also be placed on the central role of glutamate in the glutamine-glutamate and glutamine-GABA neurotransmitter cycles between neurons and astrocytes. Finally, we provide a brief and selective discussion of neuropathology associated with altered cerebral glutamate levels. PMID:27023624

  4. Nitrate Starvation Induced Changes in Root System Architecture, Carbon:Nitrogen Metabolism, and miRNA Expression in Nitrogen-Responsive Wheat Genotypes.

    PubMed

    Sinha, Subodh Kumar; Rani, Manju; Bansal, Niketa; Gayatri; Venkatesh, K; Mandal, P K

    2015-11-01

    Improvement of nutrient use efficiency in cereal crops is highly essential not only to reduce the cost of cultivation but also to save the environmental pollution, reduce energy consumption for production of these chemical fertilizers, improve soil health, and ultimately help in mitigating climate change. In the present investigation, we have studied the morphological (with special emphasis on root system architecture) and biochemical responses (in terms of assay of the key enzymes involved in N assimilation) of two N-responsive wheat genotypes, at the seedling stage, under nitrate-optimum and nitrate-starved conditions grown in hydroponics. Expression profile of a few known wheat micro RNAs (miRNAs) was also studied in the root tissue. Total root size, primary root length, and first- and second-order lateral root numbers responded significantly under nitrate-starved condition. Morphological parameters in terms of root and shoot length and fresh and dry weight of roots and shoots have also been observed to be significant between N-optimum and N-starved condition for each genotypes. Nitrate reductase (NR), glutamine synthatase (GS), and glutamate dehydrogenase (GDH) activity significantly decreased under N-starved condition. Glutamine oxoglutarate amino transferase (GOGAT) and pyruvate kinase (PK) activity was found to be genotype dependent. Most of the selected miRNAs were expressed in root tissues, and some of them showed their differential N-responsive expression. Our studies indicate that one of the N-responsive genotype (NP-890) did not get affected significantly under nitrogen starvation at seedling stage.

  5. Root-zone acidity affects relative uptake of nitrate and ammonium from mixed nitrogen sources

    NASA Technical Reports Server (NTRS)

    Vessey, J. K.; Henry, L. T.; Chaillou, S.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

    1990-01-01

    Soybean plants (Glycine max [L.] Merr. cv Ransom) were grown for 21 days on 4 sources of N (1.0 mM NO3-, 0.67 mM NO3- plus 0.33 mM NH4+, 0.33 mM NO3- plus 0.67 mM NH4+, and 1.0 mM NH4+) in hydroponic culture with the acidity of the nutrient solution controlled at pH 6.0, 5.5, 5.0, and 4.5. Dry matter and total N accumulation of the plants was not significantly affected by N-source at any of the pH levels except for decreases in these parameters in plants supplied solely with NH4+ at pH 4.5. Shoot-to-root ratios increased in plants which had an increased proportion [correction of proporiton] of NH4(+)-N in their nutrient solutions at all levels of root-zone pH. Uptake of NO3- and NH4+ was monitored daily by ion chromatography as depletion of these ions from the replenished hydroponic solutions. At all pH levels the proportion of either ion that was absorbed increased as the ratio of that ion increased in the nutrient solution. In plants which were supplied with sources of NO3- plus NH4+, NH4+ was absorbed at a ratio of 2:1 over NO3- at pH 6.0. As the pH of the root-zone declined, however, NH4+ uptake decreased and NO3- uptake increased. Thus, the NH4+ to NO3- uptake ratio declined with decreases in root-zone pH. The data indicate a negative effect of declining root-zone pH on NH4+ uptake and supports a hypothesis that the inhibition of growth of plants dependent on NH4(+)-N at low pH is due to a decline in NH4+ uptake and a consequential limitation of growth by N stress.

  6. [Effects of high temperature on Bt protein content and nitrogen metabolic physiology in boll wall of Bt cotton].

    PubMed

    Wang, Jun; Abidallah, Eltayib H M A; Hua, Ming-ming; Heng, Li; Lyu, Chun-hua; Chen, De-hua

    2015-10-01

    Bt cotton cultivar Sikang 1 (a conventional cultivar) and Sikang 3 (a hybrid cultivar) from China, and 99B (a conventional cultivar) and Daiza 1 (a hybrid cultivar) from USA were selected as experimental materials, the ball wall Bt protein content and nitrogen metabolic physiology were investigated under different high temperature levels at peak boll stage. The results showed that the Bt protein content of boll wall decreased with the increasing temperature. Compared with the control (32 °C, the boll wall Bt protein content decreased significantly when the temperature was above 38 °C for the conventional cultivars and above 40 °C for the hybrid cultivars. The Bt protein contents of cultivar Sikang 1 and 99B decreased by 53.0% and 69.5% respectively with the temperature at 38 °C, and that of cultivar Sikang 3 and Daiza 1 decreased by 64.8% and 54.1% respectively with the temperature at 40 °C. Greater reductions in the boll wall soluble protein contents and GPT activities, larger increments for the boll wall free amino acid contents and proteinsase activities were also observed when the boll wall Bt protein content was significantly reduced. Therefore, high temperature resulted in the reduction of Bt protein synthesis and increase of the insecticidal protein degradation in the boll wall significantly, which caused the reductions in boll wall Bt protein content and insect resistance.

  7. Nitrogen metabolism and gas exchange parameters associated with zinc stress in tobacco expressing an ipt gene for cytokinin synthesis.

    PubMed

    Pavlíková, Daniela; Pavlík, Milan; Procházková, Dagmar; Zemanová, Veronika; Hnilička, František; Wilhelmová, Naďa

    2014-04-15

    Increased endogenous plant cytokinin (CK) content through transformation with an isopentyl transferase (ipt) gene has been associated with improved plant stress tolerance. The impact of zinc (tested levels Zn1=250, Zn2=500, Zn3=750mgkg(-1)soil) on gas exchange parameters (net photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO2 concentration) and nitrogen utilization by plants resulted in changes of free amino acid concentrations (glutamic acid, glutamine, asparagine, aspartate, glycine, serine, cystein) and differed for transformed and non-transformed tobacco plants. For pot experiments, tobacco plants (Nicotiana tabacum L., cv. Wisconsin 38) transformed with a construct consisting of SAG12 promoter fused with the ipt gene for cytokinin synthesis (SAG plants) and its wild type (WT plants as a control) were used. Physiological analyses confirmed that SAG plants had improved zinc tolerance compared with the WT plants. The enhanced Zn tolerance of SAG plants was associated with the maintenance of accumulation of amino acids and with lower declines of photosynthetic and transpiration rates. In comparison to WT plants, SAG plants exposed to the highest Zn concentration accumulated lower concentrations of asparagine, which is a major metabolic product during senescence.

  8. Metabolism

    MedlinePlus

    Metabolism refers to all the physical and chemical processes in the body that convert or use energy, ... Tortora GJ, Derrickson BH. Metabolism. In: Tortora GJ, Derrickson ... Physiology . 14th ed. Hoboken, NJ: John Wiley & Sons; 2014:chap ...

  9. Metabolism

    MedlinePlus

    ... El metabolismo Metabolism Basics Our bodies get the energy they need from food through metabolism, the chemical ... that convert the fuel from food into the energy needed to do everything from moving to thinking ...

  10. Response of oxidative enzyme activities to nitrogen deposition affects soil concentrations of dissolved organic carbon

    USGS Publications Warehouse

    Waldrop, M.P.; Zak, D.R.

    2006-01-01

    Recent evidence suggests that atmospheric nitrate (NO3- ) deposition can alter soil carbon (C) storage by directly affecting the activity of lignin-degrading soil fungi. In a laboratory experiment, we studied the direct influence of increasing soil NO 3- concentration on microbial C cycling in three different ecosystems: black oak-white oak (BOWO), sugar maple-red oak (SMRO), and sugar maple-basswood (SMBW). These ecosystems span a broad range of litter biochemistry and recalcitrance; the BOWO ecosystem contains the highest litter lignin content, SMRO had intermediate lignin content, and SMBW leaf litter has the lowest lignin content. We hypothesized that increasing soil solution NO 3- would reduce lignolytic activity in the BOWO ecosystem, due to a high abundance of white-rot fungi and lignin-rich leaf litter. Due to the low lignin content of litter in the SMBW, we further reasoned that the NO3- repression of lignolytic activity would be less dramatic due to a lower relative abundance of white-rot basidiomycetes; the response in the SMRO ecosystem should be intermediate. We increased soil solution NO3- concentrations in a 73-day laboratory incubation and measured microbial respiration and soil solution dissolved organic carbon (DOC) and phenolics concentrations. At the end of the incubation, we measured the activity of ??-glucosidase, N-acetyl-glucosaminidase, phenol oxidase, and peroxidase, which are extracellular enzymes involved with cellulose and lignin degradation. We quantified the fungal biomass, and we also used fungal ribosomal intergenic spacer analysis (RISA) to gain insight into fungal community composition. In the BOWO ecosystem, increasing NO 3- significantly decreased oxidative enzyme activities (-30% to -54%) and increased DOC (+32% upper limit) and phenolic (+77% upper limit) concentrations. In the SMRO ecosystem, we observed a significant decrease in phenol oxidase activity (-73% lower limit) and an increase in soluble phenolic concentrations

  11. Impact of the Carbon and Nitrogen Supply on Relationships and Connectivity between Metabolism and Biomass in a Broad Panel of Arabidopsis Accessions1[W][OA

    PubMed Central

    Sulpice, Ronan; Nikoloski, Zoran; Tschoep, Hendrik; Antonio, Carla; Kleessen, Sabrina; Larhlimi, Abdelhalim; Selbig, Joachim; Ishihara, Hirofumi; Gibon, Yves; Fernie, Alisdair R.; Stitt, Mark

    2013-01-01

    Natural genetic diversity provides a powerful tool to study the complex interrelationship between metabolism and growth. Profiling of metabolic traits combined with network-based and statistical analyses allow the comparison of conditions and identification of sets of traits that predict biomass. However, it often remains unclear why a particular set of metabolites is linked with biomass and to what extent the predictive model is applicable beyond a particular growth condition. A panel of 97 genetically diverse Arabidopsis (Arabidopsis thaliana) accessions was grown in near-optimal carbon and nitrogen supply, restricted carbon supply, and restricted nitrogen supply and analyzed for biomass and 54 metabolic traits. Correlation-based metabolic networks were generated from the genotype-dependent variation in each condition to reveal sets of metabolites that show coordinated changes across accessions. The networks were largely specific for a single growth condition. Partial least squares regression from metabolic traits allowed prediction of biomass within and, slightly more weakly, across conditions (cross-validated Pearson correlations in the range of 0.27–0.58 and 0.21–0.51 and P values in the range of <0.001–<0.13 and <0.001–<0.023, respectively). Metabolic traits that correlate with growth or have a high weighting in the partial least squares regression were mainly condition specific and often related to the resource that restricts growth under that condition. Linear mixed-model analysis using the combined metabolic traits from all growth conditions as an input indicated that inclusion of random effects for the conditions improves predictions of biomass. Thus, robust prediction of biomass across a range of conditions requires condition-specific measurement of metabolic traits to take account of environment-dependent changes of the underlying networks. PMID:23515278

  12. Effects of phosphorus application on photosynthetic carbon and nitrogen metabolism, water use efficiency and growth of dwarf bamboo (Fargesia rufa) subjected to water deficit.

    PubMed

    Liu, Chenggang; Wang, Yanjie; Pan, Kaiwen; Jin, Yanqiang; Li, Wei; Zhang, Lin

    2015-11-01

    Dwarf bamboo (Fargesia rufa Yi), one of the staple foods for the endangered giant pandas, is highly susceptible to water deficit due to its shallow roots. In the face of climate change, maintenance and improvement in its productivity is very necessary for the management of the giant pandas' habitats. However, the regulatory mechanisms underlying plant responses to water deficit are poorly known. To investigate the effects of P application on photosynthetic C and N metabolism, water use efficiency (WUE) and growth of dwarf bamboo under water deficit, a completely randomized design with two factors of two watering (well-watered and water-stressed) and two P regimes (with and without P fertilization) was arranged. P application hardly changed growth, net CO2 assimilation rate (P(n)) and WUE in well-watered plants but significantly increased relative growth rate (RGR) and P(n) in water-stressed plants. The effect of P application on RGR under water stress was mostly associated with physiological adjustments rather than with differences in biomass allocation. P application maintained the balance of C metabolism in well-watered plants, but altered the proportion of nitrogenous compounds in N metabolism. By contrast, P application remarkably increased sucrose-metabolizing enzymes activities with an obvious decrease in sucrose content in water-stressed plants, suggesting an accelerated sucrose metabolism. Activation of nitrogen-metabolizing enzymes in water-stressed plants was attenuated after P application, thus slowing nitrate reduction and ammonium assimilation. P application hardly enlarged the phenotypic plasticity of dwarf bamboo in response to water in the short term. Generally, these examined traits of dwarf bamboo displayed weak or negligible responses to water-P interaction. In conclusion, P application could accelerate P(n) and sucrose metabolism and slow N metabolism in water-stressed dwarf bamboo, and as a result improved RGR and alleviated damage from soil

  13. Nitrogen-Fixing Nodules Are an Important Source of Reduced Sulfur, Which Triggers Global Changes in Sulfur Metabolism in Lotus japonicus.

    PubMed

    Kalloniati, Chrysanthi; Krompas, Panagiotis; Karalias, Georgios; Udvardi, Michael K; Rennenberg, Heinz; Herschbach, Cornelia; Flemetakis, Emmanouil

    2015-09-01

    We combined transcriptomic and biochemical approaches to study rhizobial and plant sulfur (S) metabolism in nitrogen (N) fixing nodules (Fix(+)) of Lotus japonicus, as well as the link of S-metabolism to symbiotic nitrogen fixation and the effect of nodules on whole-plant S-partitioning and metabolism. Our data reveal that N-fixing nodules are thiol-rich organs. Their high adenosine 5'-phosphosulfate reductase activity and strong (35)S-flux into cysteine and its metabolites, in combination with the transcriptional upregulation of several rhizobial and plant genes involved in S-assimilation, highlight the function of nodules as an important site of S-assimilation. The higher thiol content observed in nonsymbiotic organs of N-fixing plants in comparison to uninoculated plants could not be attributed to local biosynthesis, indicating that nodules are an important source of reduced S for the plant, which triggers whole-plant reprogramming of S-metabolism. Enhanced thiol biosynthesis in nodules and their impact on the whole-plant S-economy are dampened in plants nodulated by Fix(-) mutant rhizobia, which in most respects metabolically resemble uninoculated plants, indicating a strong interdependency between N-fixation and S-assimilation.

  14. [Effects of exogenous spermidine on the nitrogen metabolism and main mineral elements contents of tomato seedlings under saline-alkali stress].

    PubMed

    Zhang, Yi; Shi, Yu; Hu, Xiao-Hui; Zou, Zhi-Rong; Cao, Kai; Zhang, Hao

    2013-05-01

    Taking two tomato cultivars Zhongza No. 9 and Jinpengchaoguan as test objects, a hydroponic experiment was conducted to study the effects of exogenous spermidine (Spd) on the tomato seedling nitrogen metabolism and main mineral elements contents under saline-alkali stress. Under the stress, the seedling dry biomass decreased significantly, and the plant growth was inhibited. The activities of nitrate reductase (NR), glutamine synthetase (GS), and glutamate synthase (GOGAT) and the contents of nitrate nitrogen (NO3(-)-N) and total N, K, Ca2+, and Mg2+ in leaves and roots decreased significantly, while the contents of ammonium nitrogen (NH4(+)-N), and Na+ had a significant increase. The activity of glutamate dehydrogenase (GDH) in the leaves of the two cultivars and in the roots of Zhongza No. 9 increased significantly, but that in the roots of Jinpengchaoguan had less change. The total P content in the leaves of the two cultivars decreased significantly, while that in the roots of Jinpengchaoguan and Zhongza No. 9 had a significant increase and less change, respectively. Applying exogenous Spd increased the assimilation of NH4+ by the plants through increasing the NR, GS and GOGAT activities, alleviated the nitrogen metabolic disturbance caused by the saline-alkali stress, and further, promoted the absorption, release, or transportation of P, K, Ca, Mg, and Na in different organs, maintained a proper balance among the nutrients, and improved the plant saline-alkali resistance. Zhongza No. 9 was more sensitive to the saline-alkali stress than Jinpengchaoguan, and the alleviation effect of exogenous Spd on the nitrogen metabolic disturbance and nutritional out-of-balance of Zhongza No. 9 was more obvious.

  15. Macronutrient digestibility, nitrogen balance, plasma indicators of protein metabolism and mineral absorption in horses fed a ration rich in sugar beet pulp.

    PubMed

    Olsman, A F S; Huurdeman, C M; Jansen, W L; Haaksma, J; Sloet van Oldruitenborgh-Oosterbaan, M M; Beynen, A C

    2004-10-01

    In a cross-over study with six mature horses, the effect of iso-energetic replacement of dietary glucose by beet pulp on macronutrient digestibility, nitrogen metabolism and mineral absorption was studied. The test ration contained 25% beet pulp in the total dietary dry matter. Beet pulp feeding significantly lowered crude fat and non-structural carbohydrate digestibility, but had no significant effect on digestibility of other macronutrients, faecal and urinary nitrogen excretion and the faecal to urinary nitrogen excretion quotient. However, on the beet pulp diet, plasma ammonia and creatinin concentrations were significantly lower than on the glucose diet. No diet effect on magnesium absorption was observed. It is suggested that dietary beet pulp stimulates the conversion of ammonia into urea.

  16. Metabolic Profiling with Gas Chromatography-Mass Spectrometry and Capillary Electrophoresis-Mass Spectrometry Reveals the Carbon-Nitrogen Status of Tobacco Leaves Across Different Planting Areas.

    PubMed

    Zhao, Jieyu; Zhao, Yanni; Hu, Chunxiu; Zhao, Chunxia; Zhang, Junjie; Li, Lili; Zeng, Jun; Peng, Xiaojun; Lu, Xin; Xu, Guowang

    2016-02-05

    The interaction between carbon (C) and nitrogen (N) metabolism can reflect plant growth status and environmental factors. Little is known regarding the connections between C-N metabolism and growing regions under field conditions. To comprehensively investigate the relationship in mature tobacco leaves, we established metabolomics approaches based on gas chromatography-mass spectrometry (GC-MS) and capillary electrophoresis-time-of-flight-mass spectrometry (CE-TOF-MS). Approximately 240 polar metabolites were determined. Multivariate statistical analysis revealed that the growing region greatly influenced the metabolic profiles of tobacco leaves. A metabolic correlation network and related pathway maps were used to reveal the global overview of the alteration of C-N metabolism across three typical regions. In Yunnan, sugars and tricarboxylic acid (TCA) cycle intermediates were closely correlated with amino acid pools. Henan tobacco leaves showed positive correlation between the pentose phosphate pathway (PPP) intermediates and C-rich secondary metabolism. In Guizhou, the proline and asparagine had significant links with TCA cycle intermediates and urea cycle, and antioxidant accumulation was observed in response to drought. These results demonstrate that combined analytical approaches have great potential to detect polar metabolites and provide information on C-N metabolism related to planting regional characteristics.

  17. Obesity, but not Metabolic Syndrome, Negatively Affects Outcome in Bipolar Disorder

    PubMed Central

    McElroy, Susan L; Kemp, David E; Friedman, Edward S; Reilly-Harrington, Noreen A; Sylvia, Louisa G; Calabrese, Joseph R; Rabideau, Dustin J; Ketter, Terence A; Thase, Michael E; Singh, Vivek; Tohen, Mauricio; Bowden, Charles L; Bernstein, Emily E; Brody, Benjamin D; Deckersbach, Thilo; Kocsis, James H; Kinrys, Gustavo; Bobo, William V; Kamali, Masoud; McInnis, Melvin G; Leon, Andrew C.; Faraone, Stephen; Nierenberg, Andrew A; Shelton, Richard C

    2016-01-01

    Objective Examine the effects of obesity and metabolic syndrome on outcome in bipolar disorder. Method The Comparative Effectiveness of a Second Generation Antipsychotic Mood Stabilizer and a Classic Mood Stabilizer for Bipolar Disorder (Bipolar CHOICE) study randomized 482 participants with bipolar disorder in a six-month trial comparing lithium- and quetiapine-based treatment. Baseline variables were compared between groups with and without obesity, with and without abdominal obesity, and with and without metabolic syndrome, respectively. The effects of baseline obesity, abdominal obesity, and metabolic syndrome on outcomes were examined using mixed effects linear regression models. Results At baseline, 44.4% of participants had obesity, 48.0% had abdominal obesity, and 27.3% had metabolic syndrome; neither obesity, nor abdominal obesity, nor metabolic syndrome were associated with increased global severity, mood symptoms, or suicidality, or with poorer functioning or life satisfaction. Treatment groups did not differ on prevalence of obesity, abdominal obesity, or metabolic syndrome. By contrast, among the entire cohort, obesity was associated with less global improvement and less improvement in total mood and depressive symptoms, suicidality, functioning, and life satisfaction after six months of treatment. Abdominal obesity was associated with similar findings. Metabolic syndrome had no effect on outcome. Conclusion Obesity and abdominal obesity, but not metabolic syndrome, were associated with less improvement after six months of lithium- or quetiapine-based treatment. PMID:26114830

  18. Effect of amino acid composition of parenteral solutions on nitrogen retention and metabolic response in very-low-birth weight infants.

    PubMed

    Chessex, P; Zebiche, H; Pineault, M; Lepage, D; Dallaire, L

    1985-01-01

    To evaluate the influence of amino acid preparations on the metabolic response of parenterally fed immature newborn infants, nitrogen retention and plasma amino acid concentrations were compared in very-low-birth-weight infants given two parenteral regimens differing only by the composition of the infused amino acids (Travasol 10% blend B and Vamin 7%). The intakes of fluid, nitrogen, and calories were comparable. The nitrogen retention was 72% +/- 7% with Vamin and 65% +/- 6% with Travasol. The differences in plasma amino acid concentrations were consistent with the composition of the amino acid solutions. During the infusion of Vamin the increased intake of aromatic amino acids resulted in high plasma levels of tyrosine (256 +/- 233 mumol/L, range 67 to 894 mumol/L). The infusion of Travasol resulted in high plasma levels of methionine (114 +/- 39 mumol/L, range 53 to 260 mumol/L) and an elevated load of glycine, which was accompanied by an abnormally high urinary loss of this amino acid. Despite these metabolic imbalances, the growth rate over the whole study was adequate. These results emphasize the importance of the composition of amino acid solutions on the metabolic response of the very immature preterm infant.

  19. The use of metabolomics integrated with transcriptomic and proteomic studies for identifying key steps involved in the control of nitrogen metabolism in crops such as maize.

    PubMed

    Amiour, Nardjis; Imbaud, Sandrine; Clément, Gilles; Agier, Nicolas; Zivy, Michel; Valot, Benoît; Balliau, Thierry; Armengaud, Patrick; Quilleré, Isabelle; Cañas, Rafael; Tercet-Laforgue, Thérèse; Hirel, Bertrand

    2012-09-01

    Linking plant phenotype to gene and protein expression and also to metabolite synthesis and accumulation is one of the main challenges for improving agricultural production worldwide. Such a challenge is particularly relevant to crop nitrogen use efficiency (NUE). Here, the differences in leaf gene transcript, protein, and metabolite accumulation in maize subjected to long-term nitrogen (N)-deficient growth conditions at two important stages of plant development have been studied. The impact of N deficiency was examined at the transcriptomic, proteomic, and metabolomic levels. It was found that a number of key plant biological functions were either up- or down-regulated when N was limiting, including major alterations to photosynthesis, carbon (C) metabolism, and, to a lesser extent, downstream metabolic pathways. It was also found that the impact of the N deficiency stress resembled the response of plants to a number of other biotic and abiotic stresses, in terms of transcript, protein, and metabolite accumulation. The genetic and metabolic alterations were different during the N assimilation and the grain-filling period, indicating that plant development is an important component for identifying the key elements involved in the control of plant NUE. It was also found that integration of the three 'omics' studies is not straightforward, since different levels of regulation seem to occur in a stepwise manner from gene expression to metabolite accumulation. The potential use of these 'omics' studies is discussed with a view to improve our understanding of whole plant nitrogen economics, which should have applications in breeding and agronomy.

  20. Sugar Allocation to Metabolic Pathways is Tightly Regulated and Affects the Virulence of Streptococcus mutans

    PubMed Central

    Kawada-Matsuo, Miki; Oogai, Yuichi; Komatsuzawa, Hitoshi

    2016-01-01

    Bacteria take up and metabolize sugar as a carbohydrate source for survival. Most bacteria can utilize many sugars, including glucose, sucrose, and galactose, as well as amino sugars, such as glucosamine and N-acetylglucosamine. After entering the cytoplasm, the sugars are mainly allocated to the glycolysis pathway (energy production) and to various bacterial component biosynthesis pathways, including the cell wall, nucleic acids and amino acids. Sugars are also utilized to produce several virulence factors, such as capsule and lipoteichoic acid. Glutamine-fructose-6-phosphate aminotransferase (GlmS) and glucosamine-6-phosphate deaminase (NagB) have crucial roles in sugar distribution to the glycolysis pathway and to cell wall biosynthesis. In Streptococcus mutans, a cariogenic pathogen, the expression levels of glmS and nagB are coordinately regulated in response to the presence or absence of amino sugars. In addition, the disruption of this regulation affects the virulence of S. mutans. The expression of nagB and glmS is regulated by NagR in S. mutans, but the precise mechanism underlying glmS regulation is not clear. In Staphylococcus aureus and Bacillus subtilis, the mRNA of glmS has ribozyme activity and undergoes self-degradation at the mRNA level. However, there is no ribozyme activity region on glmS mRNA in S. mutans. In this review article, we summarize the sugar distribution, particularly the coordinated regulation of GlmS and NagB expression, and its relationship with the virulence of S. mutans. PMID:28036052

  1. Temperature-induced elevation of basal metabolic rate does not affect testis growth in great tits.

    PubMed

    Caro, Samuel P; Visser, Marcel E

    2009-07-01

    The timing of reproduction varies from year to year in many bird species. To adjust their timing to the prevailing conditions of that year, birds use cues from their environment. However, the relative importance of these cues, such as the initial predictive (e.g. photoperiod) and the supplemental factors (e.g. temperature), on the seasonal sexual development are difficult to distinguish. In particular, the fine-tuning effect of temperature on gonadal growth is not well known. One way temperature may affect timing is via its strong effect on energy expenditure as gonadal growth is an energy-demanding process. To study the interaction of photoperiod and temperature on gonadal development, we first exposed 35 individually housed male great tits (Parus major) to mid-long days (after 6 weeks of 8 h L:16 h D at 15 degrees C, photoperiod was set to 13 h L:11 h D at 15 degrees C). Two weeks later, for half of the males the temperature was set to 8 degrees C, and for the other half to 22 degrees C. Unilateral laparotomies were performed at weeks 5 (i.e one week before the birds were transferred to mid-long days), 8 and 11 to measure testis size. Two measures of basal metabolic rate (BMR) were performed at the end of the experiment (weeks 11 and 12). Testis size increased significantly during the course of the experiment, but independently of the temperature treatment. BMR was significantly higher in birds exposed to the cold treatment. These results show that temperature-related elevation of BMR did not impair the long-day-induced testis growth in great tits. As a consequence, temperature may not be a crucial cue and/or constraint factor in the fine-tuning of the gonadal recrudescence in male great tits, and testis growth is not a high energy-demanding seasonal process.

  2. Bole girdling affects metabolic properties and root, trunk and branch hydraulics of young ponderosa pine trees.

    PubMed

    Domec, Jean-Christophe; Pruyn, Michele L

    2008-10-01

    Effects of trunk girdling on seasonal patterns of xylem water status, water transport and woody tissue metabolic properties were investigated in ponderosa pine (Pinus ponderosa Dougl. ex P. Laws.) trees. At the onset of summer, there was a sharp decrease in stomatal conductance (g(s)) in girdled trees followed by a full recovery after the first major rainfall in September. Eliminating the root as a carbohydrate sink by girdling induced a rapid reversible reduction in g(s). Respiratory potential (a laboratory measure of tissue-level respiration) increased above the girdle (branches and upper trunk) and decreased below the girdle (lower trunk and roots) relative to control trees during the growing season, but the effect was reversed after the first major rainfall. The increase in branch respiratory potential induced by girdling suggests that the decrease in g(s) was caused by the accumulation of carbohydrates above the girdle, which is consistent with an observed increase in leaf mass per area in the girdled trees. Trunk girdling did not affect native xylem embolism or xylem conductivity. Both treated and control trunks experienced loss of xylem conductivity ranging from 10% in spring to 30% in summer. Girdling reduced xylem growth and sapwood to leaf area ratio, which in turn reduced branch leaf specific conductivity (LSC). The girdling-induced reductions in g(s) and transpiration were associated with a decrease in leaf hydraulic conductance. Two years after girdling, when root-to-shoot phloem continuity had been restored, girdled trees had a reduced density of new wood, which increased xylem conductivity and whole-tree LSC, but also vulnerability to embolism.

  3. Analysis of the Metabolic Pathways Affected by Poly(γ-glutamic Acid) in Arabidopsis thaliana Based on GeneChip Microarray.

    PubMed

    Xu, Zongqi; Lei, Peng; Feng, Xiaohai; Li, Sha; Xu, Hong

    2016-08-17

    Plant growth is promoted by poly(γ-glutamic acid) (γ-PGA). However, the molecular mechanism underlying such promotion is not yet well understood. Therefore, we used GeneChip microarrays to explore the effects of γ-PGA on gene transcription in Arabidopsis thaliana. Our results revealed 299 genes significantly regulated by γ-PGA. These differently expressed genes participate mainly in metabolic and cellular processes and in stimuli responses. The metabolic pathways linked to these differently expressed genes were also investigated. A total of 64 of the 299 differently expressed genes were shown to be directly involved in 24 pathways such as brassinosteroid biosynthesis, α-linolenic acid metabolism, phenylpropanoid biosynthesis, and nitrogen metabolism, all of which were influenced by γ-PGA. The analysis demonstrated that γ-PGA promoted nitrogen assimilation and biosynthesis of brassinosteroids, jasmonic acid, and lignins, providing a better explanation for why γ-PGA promotes growth and enhances stress tolerance in plants.

  4. Water deficit alters differentially metabolic pathways affecting important flavor and quality traits in grape berries of Cabernet Sauvignon and Chardonnay

    PubMed Central

    Deluc, Laurent G; Quilici, David R; Decendit, Alain; Grimplet, Jérôme; Wheatley, Matthew D; Schlauch, Karen A; Mérillon, Jean-Michel; Cushman, John C; Cramer, Grant R

    2009-01-01

    Background Water deficit has significant effects on grape berry composition resulting in improved wine quality by the enhancement of color, flavors, or aromas. While some pathways or enzymes affected by water deficit have been identified, little is known about the global effects of water deficit on grape berry metabolism. Results The effects of long-term, seasonal water deficit on berries of Cabernet Sauvignon, a red-wine grape, and Chardonnay, a white-wine grape were analyzed by integrated transcript and metabolite profiling. Over the course of berry development, the steady-state transcript abundance of approximately 6,000 Unigenes differed significantly between the cultivars and the irrigation treatments. Water deficit most affected the phenylpropanoid, ABA, isoprenoid, carotenoid, amino acid and fatty acid metabolic pathways. Targeted metabolites were profiled to confirm putative changes in specific metabolic pathways. Water deficit activated the expression of numerous transcripts associated with glutamate and proline biosynthesis and some committed steps of the phenylpropanoid pathway that increased anthocyanin concentrations in Cabernet Sauvignon. In Chardonnay, water deficit activated parts of the phenylpropanoid, energy, carotenoid and isoprenoid metabolic pathways that contribute to increased concentrations of antheraxanthin, flavonols and aroma volatiles. Water deficit affected the ABA metabolic pathway in both cultivars. Berry ABA concentrations were highly correlated with 9-cis-epoxycarotenoid dioxygenase (NCED1) transcript abundance, whereas the mRNA expression of other NCED genes and ABA catabolic and glycosylation processes were largely unaffected. Water deficit nearly doubled ABA concentrations within berries of Cabernet Sauvignon, whereas it decreased ABA in Chardonnay at véraison and shortly thereafter. Conclusion The metabolic responses of grapes to water deficit varied with the cultivar and fruit pigmentation. Chardonnay berries, which lack any

  5. New Features on the Environmental Regulation of Metabolism Revealed by Modeling the Cellular Proteomic Adaptations Induced by Light, Carbon, and Inorganic Nitrogen in Chlamydomonas reinhardtii

    PubMed Central

    Gérin, Stéphanie; Leprince, Pierre; Sluse, Francis E.; Franck, Fabrice; Mathy, Grégory

    2016-01-01

    Microalgae are currently emerging to be very promising organisms for the production of biofuels and high-added value compounds. Understanding the influence of environmental alterations on their metabolism is a crucial issue. Light, carbon and nitrogen availability have been reported to induce important metabolic adaptations. So far, the influence of these variables has essentially been studied while varying only one or two environmental factors at the same time. The goal of the present work was to model the cellular proteomic adaptations of the green microalga Chlamydomonas reinhardtii upon the simultaneous changes of light intensity, carbon concentrations (CO2 and acetate), and inorganic nitrogen concentrations (nitrate and ammonium) in the culture medium. Statistical design of experiments (DOE) enabled to define 32 culture conditions to be tested experimentally. Relative protein abundance was quantified by two dimensional differential in-gel electrophoresis (2D-DIGE). Additional assays for respiration, photosynthesis, and lipid and pigment concentrations were also carried out. A hierarchical clustering survey enabled to partition biological variables (proteins + assays) into eight co-regulated clusters. In most cases, the biological variables partitioned in the same cluster had already been reported to participate to common biological functions (acetate assimilation, bioenergetic processes, light harvesting, Calvin cycle, and protein metabolism). The environmental regulation within each cluster was further characterized by a series of multivariate methods including principal component analysis and multiple linear regressions. This metadata analysis enabled to highlight the existence of a clear regulatory pattern for every cluster and to mathematically simulate the effects of light, carbon, and nitrogen. The influence of these environmental variables on cellular metabolism is described in details and thoroughly discussed. This work provides an overview of the

  6. Changes in the salinity tolerance of sweet pepper plants as affected by nitrogen form and high CO2 concentration.

    PubMed

    Piñero, María C; Pérez-Jiménez, Margarita; López-Marín, Josefa; Del Amor, Francisco M

    2016-08-01

    The assimilation and availability of nitrogen in its different forms can significantly affect the response of primary productivity under the current atmospheric alteration and soil degradation. An elevated CO2 concentration (e[CO2]) triggers changes in the efficiency and efficacy of photosynthetic processes, water use and product yield, the plant response to stress being altered with respect to ambient CO2 conditions (a[CO2]). Additionally, NH4(+) has been related to improved plant responses to stress, considering both energy efficiency in N-assimilation and the overcoming of the inhibition of photorespiration at e[CO2]. Therefore, the aim of this work was to determine the response of sweet pepper plants (Capsicum annuum L.) receiving an additional supply of NH4(+) (90/10 NO3(-)/NH4(+)) to salinity stress (60mM NaCl) under a[CO2] (400μmolmol(-1)) or e[CO2] (800μmolmol(-1)). Salt-stressed plants grown at e[CO2] showed DW accumulation similar to that of the non-stressed plants at a[CO2]. The supply of NH4(+) reduced growth at e[CO2] when salinity was imposed. Moreover, NH4(+) differentially affected the stomatal conductance and water use efficiency and the leaf Cl(-), K(+), and Na(+) concentrations, but the extent of the effects was influenced by the [CO2]. An antioxidant-related response was prompted by salinity, the total phenolics and proline concentrations being reduced by NH4(+) at e[CO2]. Our results show that the effect of NH4(+) on plant salinity tolerance should be globally re-evaluated as e[CO2] can significantly alter the response, when compared with previous studies at a[CO2].

  7. Light-dark (12:12) cycle of carbon and nitrogen metabolism in Crocosphaera watsonii WH8501: relation to the cell cycle.

    PubMed

    Dron, Anthony; Rabouille, Sophie; Claquin, Pascal; Le Roy, Bertrand; Talec, Amélie; Sciandra, Antoine

    2012-04-01

    This study provides with original data sets on the physiology of the unicellular diazotrophic cyanobacterium Crocosphaera watsonii WH8501, maintained in continuous culture in conditions of obligate diazotrophy. Cultures were exposed to a 12:12 light-dark regime, representative of what they experience in nature and where growth is expected to be balanced. Nitrogen and carbon metabolism were monitored at high frequency and their dynamics was compared with the cell cycle. Results reveal a daily cycle in the physiological and biochemical parameters, tightly constrained by the timely decoupled processes of N(2) fixation and carbon acquisition. The cell division rate increased concomitantly to carbon accumulation and peaked 6 h into the light. The carbon content reached a maximum at the end of the light phase. N(2) fixation occurred mostly during the dark period and peaked between 9 and 10 h into the night, while DNA synthesis, reflected by DNA fluorescence, increased until the end of the night. Consequently, cells in G1- and S-phases present a marked decrease in their C:N ratio. Nitrogen acquisition through N(2) fixation exceeded 1.3- to 3-fold the nitrogen requirements for growth, suggesting that important amounts of nitrogen are excreted even under conditions supposed to favour balanced, carbon and nitrogen acquisitions.

  8. Size-fraction partitioning of community gene transcription and nitrogen metabolism in a marine oxygen minimum zone

    PubMed Central

    Ganesh, Sangita; Bristow, Laura A; Larsen, Morten; Sarode, Neha; Thamdrup, Bo; Stewart, Frank J

    2015-01-01

    The genetic composition of marine microbial communities varies at the microscale between particle-associated (PA; >1.6 μm) and free-living (FL; 0.2–1.6 μm) niches. It remains unclear, however, how metabolic activities differ between PA and FL fractions. We combined rate measurements with metatranscriptomics to quantify PA and FL microbial activity in the oxygen minimum zone (OMZ) of the Eastern Tropical North Pacific, focusing on dissimilatory processes of the nitrogen (N) cycle. Bacterial gene counts were 8- to 15-fold higher in the FL compared with the PA fraction. However, rates of all measured N cycle processes, excluding ammonia oxidation, declined significantly following particle (>1.6 μm) removal. Without particles, rates of nitrate reduction to nitrite (1.5–9.4nMNd−1) fell to zero and N2 production by denitrification (0.5–1.7nMNd−1) and anammox (0.3–1.9nMNd−1) declined by 53–85%. The proportional representation of major microbial taxa and N cycle gene transcripts in metatranscriptomes followed fraction-specific trends. Transcripts encoding nitrate reductase were uniform among PA and FL fractions, whereas anammox-associated transcripts were proportionately enriched up to 15-fold in the FL fraction. In contrast, transcripts encoding enzymes for N2O and N2 production by denitrification were enriched up to 28-fold in PA samples. These patterns suggest that the majority of N cycle activity, excluding N2O and N2 production by denitrification, is confined to a FL majority that is critically dependent on access to particles, likely as a source of organic carbon and inorganic N. Variable particle distributions may drive heterogeneity in N cycle activity and gene expression in OMZs. PMID:25848875

  9. Nitrogen fertilization rate affects feeding, larval performance, and oviposition preference of the beet armyworm, Spodoptera exigua, on cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrogen (N) is one of the most critical chemical elements for plant and animal growth. Development and oviposition of the beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) was studied in relation to varying nitrogen levels in cotton, Gossypium hirsutum L. The development of S. exig...

  10. C1 Metabolism Inhibition and Nitrogen Deprivation Trigger Triacylglycerol Accumulation in Arabidopsis thaliana Cell Cultures and Highlight a Role of NPC in Phosphatidylcholine-to-Triacylglycerol Pathway

    PubMed Central

    Meï, Coline E.; Cussac, Mathilde; Haslam, Richard P.; Beaudoin, Frédéric; Wong, Yung-Sing; Maréchal, Eric; Rébeillé, Fabrice

    2017-01-01

    Triacylglycerol (TAG) accumulation often occurs in growth limiting conditions such as nutrient deprivations. We analyzed and compared the lipid contents of Arabidopsis cells grown under two conditions that inhibited growth as a way to study interactions between membrane and storage lipids. In order to inhibit C1 metabolism, the first condition utilized methotrexate (MTX), a drug that inhibits methyl transfer reactions and potentially reduces Pi-choline synthesis, the polar head of phosphatidylcholine (PC). MTX-treated cells displayed a 10- to 15-fold increase in TAG compared to that found in control cells. This corresponded to a net increase of lipids as the total amount of membrane glycerolipids was minimally affected. Under this condition, PC homeostasis appeared tightly regulated and not strictly dependent on the rate of Pi-choline synthesis. The second condition we investigated involved nitrogen deprivation. Here, we observed a 40-fold increase of TAG. In these cells, the overall lipid content remained unchanged, but membrane lipids decreased by a factor of two suggesting a reduction of the membrane network and a rerouting of membrane lipids to storage lipids. Under all conditions, fatty acid (FA) analyses showed that the FA composition of TAG was comparable to that in PC, but different from that in acyl-CoA, suggesting that TAG accumulation involved PC-derived DAG moieties. In agreement, analyses by qPCR of genes coding for TAG synthesis showed a strong increase of non-specific phospholipase C (NPC) expressions, and experiments using labeled (fluorescent) PC indicated higher rates of PC-to-TAG conversion under both situations. These results highlight a role for NPC in plant cell oil production. PMID:28101097

  11. Activity affects intraspecific body-size scaling of metabolic rate in ectothermic animals.

    PubMed

    Glazier, Douglas Stewart

    2009-10-01

    Metabolic rate is commonly thought to scale with body mass (M) to the 3/4 power. However, the metabolic scaling exponent (b) may vary with activity state, as has been shown chiefly for interspecific relationships. Here I use a meta-analysis of literature data to test whether b changes with activity level within species of ectothermic animals. Data for 19 species show that b is usually higher during active exercise (mean +/- 95% confidence limits = 0.918 +/- 0.038) than during rest (0.768 +/- 0.069). This significant upward shift in b to near 1 is consistent with the metabolic level boundaries hypothesis, which predicts that maximal metabolic rate during exercise should be chiefly influenced by volume-related muscular power production (scaling as M (1)). This dependence of b on activity level does not appear to be a simple temperature effect because body temperature in ectotherms changes very little during exercise.

  12. Vertical Chlorophyll Canopy Structure Affects the Remote Sensing Based Predictability of LAI, Chlorophyll and Leaf Nitrogen in Agricultural Fields

    NASA Astrophysics Data System (ADS)

    Boegh, E.; Houborg, R.; Bienkowski, J.; Braban, C. F.; Dalgaard, T.; van Dijk, N.; Dragosits, U.; Holmes, E.; Magliulo, V.; Schelde, K.; Di Tommasi, P.; Vitale, L.; Theobald, M.; Cellier, P.; Sutton, M.

    2012-12-01

    Leaf nitrogen and leaf surface area influence the exchange of gases between terrestrial ecosystems and the atmosphere, and they play a significant role in the global cycles of carbon, nitrogen and water. Remote sensing can be used to estimate leaf area index (LAI), chlorophyll content (CHL) and leaf nitrogen (N), but methods are often developed using plot-scale data and not verified over extended regions characterized by variations in environmental boundary conditions (soil, atmosphere) and canopy structures. Estimation of N can be indirect due to its association with CHL, however N is also included in pigments such as carotenoids and anthocyanin which have different spectral signatures than CHL. Photosynthesis optimization theory suggests that plants will distribute their N resources in proportion to the light gradient within the canopy. Such vertical variation in CHL and N complicates the evaluation of remote sensing-based methods. Typically remote sensing studies measure CHL of the upper leaf, which is then multiplied by the green LAI to represent canopy chlorophyll content, or random sampling is used. In this study, field measurements and high spatial resolution (10-20 m) remote sensing images acquired from the HRG and HRVIR sensors aboard the SPOT satellites were used to assess the predictability of LAI, CHL and N in five European agricultural landscapes located in Denmark, Scotland (United Kingdom), Poland, The Netherlands and Italy . All satellite images were atmospherically using the 6SV1 model with atmospheric inputs estimated by MODIS and AIRS data. Five spectral vegetation indices (SVIs) were calculated (the Normalized Difference Vegetation index, the Simple Ratio, the Enhanced Vegetation Index-2, the Green Normalized Difference Vegetation Index, and the green Chlorophyll Index), and an image-based inverse canopy radiative transfer modelling system, REGFLEC (REGularized canopy reFLECtance) was applied to each of the five European landscapes. While the

  13. Use of transcriptomics and co-expression networks to analyze the interconnections between nitrogen assimilation and photorespiratory metabolism

    PubMed Central

    Pérez-Delgado, Carmen M.; Moyano, Tomás C.; García-Calderón, Margarita; Canales, Javier; Gutiérrez, Rodrigo A.; Márquez, Antonio J.; Betti, Marco

    2016-01-01

    Nitrogen is one of the most important nutrients for plants and, in natural soils, its availability is often a major limiting factor for plant growth. Here we examine the effect of different forms of nitrogen nutrition and of photorespiration on gene expression in the model legume Lotus japonicus with the aim of identifying regulatory candidate genes co-ordinating primary nitrogen assimilation and photorespiration. The transcriptomic changes produced by the use of different nitrogen sources in leaves of L. japonicus plants combined with the transcriptomic changes produced in the same tissue by different photorespiratory conditions were examined. The results obtained provide novel information on the possible role of plastidic glutamine synthetase in the response to different nitrogen sources and in the C/N balance of L. japonicus plants. The use of gene co-expression networks establishes a clear relationship between photorespiration and primary nitrogen assimilation and identifies possible transcription factors connected to the genes of both routes. PMID:27117340

  14. Dietary copper level affects copper metabolism during lipopolysaccharide-induced immunological stress in chicks.

    PubMed

    Koh, T S; Peng, R K; Klasing, K C

    1996-07-01

    Two experiments were conducted to examine the effect of dietary Cu level on Cu metabolism during the acute phase response in broiler chicks with adequate (Experiment 1) or deficient (Experiment 2) Cu. Diets based on cornstarch and isolated soybean protein were used to formulate a basal diet, and basal diet plus either 5, 10, or 15 mg/kg additional Cu as either CuO or CuSO4. Each diet was fed to six pens of five chicks per pen (Experiment 1) or eight pens of five chicks (Experiment 2). Half of the chicks on each diet were injected with Salmonella typhymurium lipopolysaccharide (LPS) on alternate days. In Experiment 1, LPS significantly decreased daily gain, feed intake, and feed efficiency (P < 0.01) and increased the concentration of Cu in blood plasma (P < 0.01). In the uninjected birds, adding 5, 10, or 15 mg/kg Cu as CuO or 15 mg/kg Cu as CuSO4 increased the rate of gain over that of chicks fed the basal diet. In the birds challenged with LPS, 10 mg/kg Cu as CuO increased the rate of gain and efficiency compared to those of chicks fed the basal diet. Addition of CuSO4 to the diet of chicks challenged with LPS did not affect gain, intake, or feed efficiency compared to those of chicks fed the basal diet. Ceruloplasmin levels were higher in chicks challenged with LPS than in control chicks (P = 0.03), and this difference tended to be greater in chickens fed CuO than in chickens fed CuSO4 (P = 0.07). In chicks challenged with LPS, feeding CuO at all levels and feeding CuSO4 to give 10 or 15 mg/kg Cu increased ceruloplasmin levels above that of chicks fed the basal diet. Hepatic Mn superoxide dismutase (SOD) and Cu/Zn SOD were not influenced by dietary Cu level or source or LPS. Results of Experiment 2 were similar to those of Experiment 1 except that supplemental CuSO4 and CuO gave similar increases in gain and CuSO4 was more effective at increasing ceruloplasmin levels. Chicks given supplemental Cu had higher ceruloplasmin levels following challenge with LPS than

  15. Bisphenol A affects early bovine embryo development and metabolism that is negated by an oestrogen receptor inhibitor