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Sample records for nitrogen affects cluster

  1. 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

  2. Do cluster properties affect the quenching rate?

    NASA Astrophysics Data System (ADS)

    Raichoor, A.; Andreon, S.

    2014-10-01

    The quenching rate is known to depend on galaxy stellar mass and environment, however, possible dependences on the hosting halo properties, such as mass, richness, and dynamical status, are still debated. The determination of these dependences is hampered by systematics, induced by noisy estimates of cluster mass or by the lack of control on galaxy stellar mass, which may mask existing trends or introduce fake trends. We studied a sample of local clusters (20 with 0.02 < z < 0.1 and log (M200/M⊙) ≳ 14), selected independent of the galaxy properties under study, having homogeneous optical photometry and X-ray estimated properties. Using those top quality measurements of cluster mass, hence of cluster scale, richness, iron abundance, and cooling time/presence of a cool-core, we study the simultaneous dependence of quenching on these cluster properties on galaxy stellar mass M and normalised cluster-centric distance r/r200. We found that the quenching rate can be completely described by two variables only, galaxy stellar mass and normalised cluster-centric distance, and is independent of halo properties (mass, richness, iron abundance, and central cooling time/presence of a cool-core). These halo properties change, in most cases, by less than 3% the probability that a galaxy is quenched, once the mass-size (M200 - r200) scaling relation is accounted for through cluster-centric distance normalisation. Appendix A is available in electronic form at http://www.aanda.org

  3. Carbon and nitrogen abundance variations in globular cluster red giants

    NASA Astrophysics Data System (ADS)

    Martell, Sarah L.

    2008-06-01

    This dissertation describes investigations into two of the persistent questions of elemental abundances in Galactic globular clusters: the phenomenon of deep mixing, observed through the progressive depletion of surface carbon abundance as stars evolve along the red giant branch, and abundance bimodality, a phenomenon observed only in globular clusters, in which a subset of stars in a given globular cluster have a distinctive pattern of elemental enhancements and depletions relative to the Solar pattern. The first chapter gives an introduction to the history of globular cluster abundance studies, with particular focus on low-resolution spectroscopy. For both deep mixing and abundance bimodality, the leading theoretical models and the data which support and challenge them are laid out. Each section ends with a description of presently-unanswered questions; these are the motivation for the various projects contained in this dissertation. The second chapter describes the use of molecular handstrengths for determining elemental abundances from low-resolution spectra, and introduces a new CH bandstrength index that is designed to be sensitive to carbon abundance and insensitive to nitrogen abundance in Pop. II red giants over a wide range of metallicity. Various CH indices defined elsewhere in the literature are also discussed, and are shown to have comparable accuracy to the new index only over a limited range of stellar properties. Carbon abundances determined using the new CH index are compared to literature abundances for a few stars, and general concordance with published abundances is found. The third chapter contains a large-scale application of the new CH index: a survey of present-day carbon abundances and calculated carbon depletion rates in bright red giants belonging to eleven Galactic globular clusters spanning the full metallicity range of halo globular clusters. Targets were selected with similar evolutionary states, were observed with one instrument on

  4. How clustering dark energy affects matter perturbations

    NASA Astrophysics Data System (ADS)

    Mehrabi, A.; Basilakos, S.; Pace, F.

    2015-09-01

    The rate of structure formation in the Universe is different in homogeneous and clustered dark energy models. The degree of dark energy clustering depends on the magnitude of its effective sound speed c2_eff and for c2_eff=0 dark energy clusters in a similar fashion to dark matter while for c2_eff=1 it stays (approximately) homogeneous. In this paper we consider two distinct equations of state for the dark energy component, wd = const and w_d=w_0+w_1(z/1+z) with c2_eff as a free parameter and we try to constrain the dark energy effective sound speed using current available data including Type Ia supernovae, baryon acoustic oscillation, cosmic microwave background shift parameter (Planck and WMAP), Hubble parameter, big bang nucleosynthesis and the growth rate of structures fσ8(z). At first we derive the most general form of the equations governing dark matter and dark energy clustering under the assumption that c2_eff=const. Finally, performing an overall likelihood analysis we find that the likelihood function peaks at c2_eff=0; however, the dark energy sound speed is degenerate with respect to the cosmological parameters, namely Ωm and wd.

  5. Co-regulation of the nitrogen-assimilatory gene cluster in Clostridium saccharobutylicum.

    PubMed

    Stutz, Helen E; Quixley, Keith W M; McMaster, Lynn D; Reid, Sharon J

    2007-09-01

    Nitrogen assimilation is important during solvent production by Clostridium saccharobutylicum NCP262, as acetone and butanol yields are significantly affected by the nitrogen source supplied. Growth of this bacterium was dependent on the concentration of organic nitrogen supplied and the expression of the assimilatory enzymes, glutamine synthetase (GS) and glutamate synthase (GOGAT), was shown to be induced in nitrogen-limiting conditions. The regions flanking the gene encoding GS, glnA, were isolated from C. saccharobutylicum genomic DNA, and DNA sequencing revealed that the structural genes encoding the GS (glnA) and GOGAT (gltA and gltB) enzymes were clustered together with the nitR gene in the order glnA-nitR-gltAB. RNA analysis showed that the glnA-nitR and the gltAB genes were co-transcribed on 2.3 and 6.2 kb RNA transcripts respectively, and that all four genes were induced under the same nitrogen-limiting conditions. Complementation of an Escherichia coli gltD mutant, lacking a GOGAT small subunit, was achieved only when both the C. saccharobutylicum gltA and gltB genes were expressed together under anaerobic conditions. This is believed to be the first functional analysis of a gene cluster encoding the key enzymes of nitrogen assimilation, GS and GOGAT. A similar gene arrangement is seen in Clostridium beijerinckii NCIMB 8052, and based on the common regulatory features of the promoter regions upstream of the glnA operons in both species, we suggest a model for their co-ordinated regulation by an antitermination mechanism as well as antisense RNA. PMID:17768251

  6. A cluster analysis of affective states before and during competition.

    PubMed

    Martinent, Guillaume; Nicolas, Michel; Gaudreau, Patrick; Campo, Mickaël

    2013-12-01

    The purposes of the current study were to identify affective profiles of athletes both before and during the competition and to examine differences between these profiles on coping and attainment of sport goals among a sample of 306 athletes. The results of hierarchical (Ward's method) and nonhierarchical (k means) cluster analyses revealed four different clusters both before and during the competition. The four clusters were very similar at the two measurement occasions: high positive affect facilitators (n = 88 and 81), facilitators (n = 75 and 25), low affect debilitators (n = 83 and 127), and high negative affect debilitators (n = 60 and 73). Results of MANOVAs revealed that coping and attainment of sport achievement goal significantly differed across the affective profiles. Results are discussed in terms of current research on positive and negative affective states. PMID:24334321

  7. 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

  8. Assessing the distinguishable cluster approximation based on the triple bond-breaking in the nitrogen molecule

    NASA Astrophysics Data System (ADS)

    Rishi, Varun; Perera, Ajith; Bartlett, Rodney J.

    2016-03-01

    Obtaining the correct potential energy curves for the dissociation of multiple bonds is a challenging problem for ab initio methods which are affected by the choice of a spin-restricted reference function. Coupled cluster (CC) methods such as CCSD (coupled cluster singles and doubles model) and CCSD(T) (CCSD + perturbative triples) correctly predict the geometry and properties at equilibrium but the process of bond dissociation, particularly when more than one bond is simultaneously broken, is much more complicated. New modifications of CC theory suggest that the deleterious role of the reference function can be diminished, provided a particular subset of terms is retained in the CC equations. The Distinguishable Cluster (DC) approach of Kats and Manby [J. Chem. Phys. 139, 021102 (2013)], seemingly overcomes the deficiencies for some bond-dissociation problems and might be of use in quasi-degenerate situations in general. DC along with other approximate coupled cluster methods such as ACCD (approximate coupled cluster doubles), ACP-D45, ACP-D14, 2CC, and pCCSD(α, β) (all defined in text) falls under a category of methods that are basically obtained by the deletion of some quadratic terms in the double excitation amplitude equation for CCD/CCSD (coupled cluster doubles model/coupled cluster singles and doubles model). Here these approximate methods, particularly those based on the DC approach, are studied in detail for the nitrogen molecule bond-breaking. The N2 problem is further addressed with conventional single reference methods but based on spatial symmetry-broken restricted Hartree-Fock (HF) solutions to assess the use of these references for correlated calculations in the situation where CC methods using fully symmetry adapted SCF solutions fail. The distinguishable cluster method is generalized: 1) to different orbitals for different spins (unrestricted HF based DCD and DCSD), 2) by adding triples correction perturbatively (DCSD(T)) and iteratively (DCSDT

  9. Assessing the distinguishable cluster approximation based on the triple bond-breaking in the nitrogen molecule.

    PubMed

    Rishi, Varun; Perera, Ajith; Bartlett, Rodney J

    2016-03-28

    Obtaining the correct potential energy curves for the dissociation of multiple bonds is a challenging problem for ab initio methods which are affected by the choice of a spin-restricted reference function. Coupled cluster (CC) methods such as CCSD (coupled cluster singles and doubles model) and CCSD(T) (CCSD + perturbative triples) correctly predict the geometry and properties at equilibrium but the process of bond dissociation, particularly when more than one bond is simultaneously broken, is much more complicated. New modifications of CC theory suggest that the deleterious role of the reference function can be diminished, provided a particular subset of terms is retained in the CC equations. The Distinguishable Cluster (DC) approach of Kats and Manby [J. Chem. Phys. 139, 021102 (2013)], seemingly overcomes the deficiencies for some bond-dissociation problems and might be of use in quasi-degenerate situations in general. DC along with other approximate coupled cluster methods such as ACCD (approximate coupled cluster doubles), ACP-D45, ACP-D14, 2CC, and pCCSD(α, β) (all defined in text) falls under a category of methods that are basically obtained by the deletion of some quadratic terms in the double excitation amplitude equation for CCD/CCSD (coupled cluster doubles model/coupled cluster singles and doubles model). Here these approximate methods, particularly those based on the DC approach, are studied in detail for the nitrogen molecule bond-breaking. The N2 problem is further addressed with conventional single reference methods but based on spatial symmetry-broken restricted Hartree-Fock (HF) solutions to assess the use of these references for correlated calculations in the situation where CC methods using fully symmetry adapted SCF solutions fail. The distinguishable cluster method is generalized: 1) to different orbitals for different spins (unrestricted HF based DCD and DCSD), 2) by adding triples correction perturbatively (DCSD(T)) and iteratively (DCSDT

  10. 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...

  11. 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...

  12. 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...

  13. 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...

  14. 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...

  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. Climate variability and nitrogen rate interactions affecting corn nitrogen use efficiency in Alabama

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrogen (N) fertilization is an important practice to increase yield; however, plant–soil interactions to in-season changes in climatic conditions result on site-specific responses of corn to nitrogen rates. The objective of this study was to evaluate the effect of different climatic conditions and...

  17. 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.

  18. Identification of Nitrogen-Fixing Genes and Gene Clusters from Metagenomic Library of Acid Mine Drainage

    PubMed Central

    Yin, Huaqun; Liang, Yili; Cong, Jing; Liu, Xueduan

    2014-01-01

    Biological nitrogen fixation is an essential function of acid mine drainage (AMD) microbial communities. However, most acidophiles in AMD environments are uncultured microorganisms and little is known about the diversity of nitrogen-fixing genes and structure of nif gene cluster in AMD microbial communities. In this study, we used metagenomic sequencing to isolate nif genes in the AMD microbial community from Dexing Copper Mine, China. Meanwhile, a metagenome microarray containing 7,776 large-insertion fosmids was constructed to screen novel nif gene clusters. Metagenomic analyses revealed that 742 sequences were identified as nif genes including structural subunit genes nifH, nifD, nifK and various additional genes. The AMD community is massively dominated by the genus Acidithiobacillus. However, the phylogenetic diversity of nitrogen-fixing microorganisms is much higher than previously thought in the AMD community. Furthermore, a 32.5-kb genomic sequence harboring nif, fix and associated genes was screened by metagenome microarray. Comparative genome analysis indicated that most nif genes in this cluster are most similar to those of Herbaspirillum seropedicae, but the organization of the nif gene cluster had significant differences from H. seropedicae. Sequence analysis and reverse transcription PCR also suggested that distinct transcription units of nif genes exist in this gene cluster. nifQ gene falls into the same transcription unit with fixABCX genes, which have not been reported in other diazotrophs before. All of these results indicated that more novel diazotrophs survive in the AMD community. PMID:24498417

  19. Identifying At-Risk Students in General Chemistry via Cluster Analysis of Affective Characteristics

    ERIC Educational Resources Information Center

    Chan, Julia Y. K.; Bauer, Christopher F.

    2014-01-01

    The purpose of this study is to identify academically at-risk students in first-semester general chemistry using affective characteristics via cluster analysis. Through the clustering of six preselected affective variables, three distinct affective groups were identified: low (at-risk), medium, and high. Students in the low affective group…

  20. 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...

  1. Cultivar and nitrogen fertilizer rate affect yield and nitrogen use efficiency in irrigated durum wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Optimizing nitrogen (N) management and using cultivars with high N use efficiency (NUE) are of great importance for durum wheat (Triticum durum L.) producers in irrigated desert production systems. Field experiments with six durum wheat cultivars (Ocotillo, Orita, Kronos, Havasu, Duraking, and Toppe...

  2. Nitrogen, stover and tillage management affect nitrogen use efficiency in continuous corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improving nitrogen use efficiency (NUE) in corn (Zea mays L.) is critical for optimizing yield and reducing environmental impact. Stover removal in continuous corn (CC) for biofuel production, coupled with reduced-tillage systems, could alter NUE and residual soil nitrate-N. Experiments were conduct...

  3. 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...

  4. 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

  5. Nitrogen and hydrophosphate affects glycolipids composition in microalgae.

    PubMed

    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

  6. Physics of Galaxy Clusters and How it Affects Cosmological Tests

    NASA Technical Reports Server (NTRS)

    Vikhlinin, Alexey; Oliversen, Ronald J. (Technical Monitor)

    2002-01-01

    We have worked on the analysis of the Chandra observations of the nearby and distant clusters of galaxies, and on the expansion of the sample of distant X-ray clusters based on the archival ROSAT PSPC data. Some of the scientific results are discussed.

  7. How the Clustering of Phonological Neighbors Affects Visual Word Recognition

    ERIC Educational Resources Information Center

    Yates, Mark

    2013-01-01

    In recent years, a new scientific field known as network science has been emerging. Network science is concerned with understanding the structure and properties of networks. One concept that is commonly used in describing a network is how the nodes in the network cluster together. The current research applied the idea of clustering to the study of…

  8. Sensory Clusters of Toddlers with Autism Spectrum Disorders: Differences in Affective Symptoms

    ERIC Educational Resources Information Center

    Ben-Sasson, A.; Cermak, S. A.; Orsmond, G. I.; Tager-Flusberg, H.; Kadlec, M. B.; Carter, A. S.

    2008-01-01

    Background: Individuals with autism spectrum disorders (ASDs) show variability in their sensory behaviors. In this study we identified clusters of toddlers with ASDs who shared sensory profiles and examined differences in affective symptoms across these clusters. Method: Using cluster analysis 170 toddlers with ASDs were grouped based on parent…

  9. Spatial variability of soil nitrogen in a hilly valley: Multiscale patterns and affecting factors.

    PubMed

    Zhang, Shirong; Xia, Chunlan; Li, Ting; Wu, Chungui; Deng, Ouping; Zhong, Qinmei; Xu, Xiaoxun; Li, Yun; Jia, Yongxia

    2016-09-01

    Estimating the spatial distribution of soil nitrogen at different scales is crucial for improving soil nitrogen use efficiency and controlling nitrogen pollution. We evaluated the spatial variability of soil total nitrogen (TN) and available nitrogen (AN) in the Fujiang River Valley, a typical hilly region composed of low, medium and high hills in the central Sichuan Basin, China. We considered the two N forms at single hill, landscape and valley scales using a combined method of classical statistics, geostatistics and a geographic information system. The spatial patterns and grading areas of soil TN and AN were different among hill types and different scales. The percentages of higher grades of the two nitrogen forms decreased from low, medium to high hills. Hill type was a major factor determining the spatial variability of the two nitrogen forms across multiple scales in the valley. The main effects of general linear models indicated that the key affecting factors of soil TN and AN were hill type and fertilization at the single hill scale, hill type and soil type at the landscape scale, and hill type, slope position, parent material, soil type, land use and fertilization at the valley scale. Thus, the effects of these key factors on the two soil nitrogen forms became more significant with upscaling. PMID:27135562

  10. Physics of Galaxy Clusters and How it Affects Cosmological Tests

    NASA Technical Reports Server (NTRS)

    Oliversen, Ronald J. (Technical Monitor); Vikhlinin, Alexey

    2004-01-01

    The main activities in 2004 were focused on completion of the new 400 square degrees ROSAT PSPC survey for distant galaxy clusters. We observed and reduced optical spectra for all X-ray candidates and now we have complete identification for a statistically complete sample of distant 283 clusters. The papers describing the cluster catalog and first science results are in preparation and will be submitted in early 2005. We also completed a project to measure temperature and density profiles at large radii using Chandra observations of a 11 well exposed low-redshift clusters. We were able to demonstrate that the density, temperature, and total mass profiles are self-similar at large radii. This analysis has led to significant improvements in determination of the cluster baryon fraction as well as cosmologically important scaling relations, such as Mtot-T. The paper describing these results is submitted to ApJ in November, 2004. We continued to study evolution of the cluster scaling relations at high redshifts using Chandra and XMM data. We developed code for image and spectral deconvolution of the XMM observations. This code was used to reconstruct the distribution of baryons and total mass from observations of distant clusters which suffer from the finite size of the XMM PSF. This study allowed us to derive a high-redshift relation between cluster temperature and mass and compare it with the local relation obtained. The paper describing the first results is submitted to the ApJ. However, the project is still on-going as more distant cluster observations enter XMh4 and Chandra public data archives. We continued our work on improving techniques for accurate measurements of the cluster mass function and obtaining cosmological constraints from such observations. We published (ApJ, 601, 610) a study in which we derived the baryon mass function for a complete sample of low-redshift clusters. These papers argued that it was an excellent proxy for the total mass function

  11. 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

  12. 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...

  13. Bonding of nitrogen atoms on Cu/001/ surfaces - A cluster approach

    NASA Technical Reports Server (NTRS)

    Yu, H. L.; Whiting, E. E.

    1979-01-01

    A study of the chemisorption of nitrogen atoms on a copper surface has been performed, based on an analysis of the electronic structure of the Cu5N cluster obtained from self-consistent-field X-alpha scattered-wave calculations. Calculations show that the chemisorption of nitrogen on Cu(001) surfaces induces peaks below and above the Cu d-band region in the total density of states curve. The bonding orbitals formed between the N 2p and the Cu valence orbitals are generally found near the bottom of the Cu d-band region, while the antibonding orbitals formed between the N 2p and Cu orbitals are found to lie above the Cu d-band region. These hybridized orbitals involving the N 2p orbital gave a satisfactory interpretation of the adsorbate-induced structure reported in N/Cu(001) ultraviolet photoemission studies.

  14. Nitrogen and water affect direct and indirect plant systemic induced defense in cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We tested the affects of nitrogen levels and water availability on the ability of cotton plants to deter feeding by Spodoptera exigua larvae through induction of anti-feedant chemicals by the cotton plant, and to attract the biological control agent, Micropitis crociepes through induction of chemica...

  15. Photoelectron spectroscopy of the nitrogen dimer (N2)2 and clusters (N2)n: N2 dimer revealed as the chromophore in photoionization of condensed nitrogen

    NASA Astrophysics Data System (ADS)

    Carnovale, Frank; Peel, J. Barrie; Rothwell, Richard G.

    1988-01-01

    The He i photoelectron spectra of gas-phase nitrogen dimer and nitrogen clusters have been measured in a pulsed cluster beam. The dimer (N2)2 is characterized by broad bands with vertical ionization energies which are 0.3±0.1 eV lower than for N2 monomer. The bands observed for a mixture of small clusters, estimated to be of average size N¯=10, are identical to the dimer bands except for further shifts of 0.3 eV to lower ionization energies. The clusters bandwidths and band shapes are virtually the same as measured for thin films of condensed N2, indicating that the nitrogen dimer (N2)2 is the ionization chromophore in each case. This offers support for Haberland's hypothesis that ionization of any Mn cluster produces the ion M+2Mn-2 provided M is a closed-shell atom or molecule. The theory of electronic relaxation polarization of the dielectric medium, which explains the gas-to-solid ionization energy shifts, is modified for the case of finite clusters and to account for dimer ion formation.

  16. Greenhouse tomato limited cluster production systems: crop management practices affect yield

    NASA Technical Reports Server (NTRS)

    Logendra, L. S.; Gianfagna, T. J.; Specca, D. R.; Janes, H. W.

    2001-01-01

    Limited-cluster production systems may be a useful strategy to increase crop production and profitability for the greenhouse tomato (Lycopersicon esculentum Mill). In this study, using an ebb-and-flood hydroponics system, we modified plant architecture and spacing and determined the effects on fruit yield and harvest index at two light levels. Single-cluster plants pruned to allow two leaves above the cluster had 25% higher fruit yields than did plants pruned directly above the cluster; this was due to an increase in fruit weight, not fruit number. Both fruit yield and harvest index were greater for all single-cluster plants at the higher light level because of increases in both fruit weight and fruit number. Fruit yield for two-cluster plants was 30% to 40% higher than for single-cluster plants, and there was little difference in the dates or length of the harvest period. Fruit yield for three-cluster plants was not significantly different from that of two-cluster plants; moreover, the harvest period was delayed by 5 days. Plant density (5.5, 7.4, 9.2 plants/m2) affected fruit yield/plant, but not fruit yield/unit area. Given the higher costs for materials and labor associated with higher plant densities, a two-cluster crop at 5.5 plants/m2 with two leaves above the cluster was the best of the production system strategies tested.

  17. Vibronic structure of the cyclopentadienyl radical and its nonrigid van der Waals cluster with nitrogen

    NASA Astrophysics Data System (ADS)

    Sun, S.; Bernstein, E. R.

    1995-09-01

    Fluorescence excitation and two color mass resolved excitation spectroscopy are employed to study the D1(2A2″)←D0(2E1″) vibronic transitions of the cyclopentadienyl radical (cpd) and its van der Waals cluster with nitrogen. The radical is created by photolysis of the cyclopentadiene dimer and cooled by expansion from a supersonic nozzle. The cpd(N2)1 cluster is generated in this cooling process. Mass resolved excitation spectra of cpd are obtained for the first 1200 cm-1 of the D1←D0 transition. The excitation spectrum of cpd(N2)1 shows a complicated structure for the origin transition. With the application of hole burning spectroscopy, we are able to assign all the cluster transitions to a single isomer. The features are assigned to a 55 cm-1 out-of-plane van der Waals mode stretch and contortional (rotational) motions of the N2 molecule with respect to the cpd radical. Empirical potential energy calculations are used to predict the properties of this cluster and yield the following results: (1) the N2 molecular axis is perpendicular to the cpd fivefold axis and parallel to the plane of the cpd ring with the two molecular centers of mass lying on the fivefold ring axis; (2) the binding energy of cpd(N2)1 is 434 cm-1; and (3) the rotational motion of the N2 molecule is essentially unhindered about the cpd fivefold axis. The molecular symmetry group D5h(MS) is applied to the nonrigid cluster, and optical selection rules exclude even↔odd transitions (Δn=0, ±2, ±4,... allowed) between the different contortional levels. Tentative assignments are given to the observed contortional features based on these considerations. The barrier to internal rotation is also small in the excited state. The results for the cpd(N2)1 van der Waals cluster are compared to those for the benzene (N2)1 and benzyl radical (N2)1 clusters.

  18. Gephyrin expression and clustering affects the size of glutamatergic synaptic contacts

    PubMed Central

    Yu, Wendou; De Blas, Angel L.

    2009-01-01

    We have recently shown that disrupting the expression and postsynaptic clustering of gephyrin in cultured hippocampal pyramidal cells, by either gephyrin RNAi (RNA interference) or overexpression of a dominant negative gephyrin-EGFP fusion protein, leads to decreased number of postsynaptic gephyrin and GABAA receptor clusters and to reduced GABAergic innervation of these cells. On the other hand, increasing gephyrin expression led to a small increase in the number of gephyrin and GABAA receptor clusters and to little or no effect on GABAergic innervation. We are now reporting that altering gephyrin expression and clustering affects the size but not the density of glutamatergic synaptic contacts. Knocking down gephyrin with gephyrin RNAi, or preventing gephyrin clustering by overexpression of the dominant negative gephyrin-EGFP fusion protein, leads to larger postsynaptic PSD-95 clusters and larger presynaptic glutamatergic terminals. On the other hand, overexpression of gephyrin leads to slightly smaller PSD-95 clusters and presynaptic glutamatergic terminals. The change in size of PSD-95 clusters were accompanied by a parallel change in the size of NR2-NMDA receptor clusters. It is concluded that the levels of expression and clustering of gephyrin, a protein that concentrates at the postsynaptic complex of the inhibitory synapses, not only has homotypic effects on GABAergic synaptic contacts, but also has heterotypic effects on glutamatergic synaptic contacts. We are proposing that gephyrin is a counterpart of the postsynaptic glutamatergic scaffold protein PSD-95 in regulating the number and/or size of the excitatory and inhibitory synaptic contacts. PMID:18199120

  19. 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. PMID:27555847

  20. 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

  1. Familial Clustering of Executive Functioning in Affected Sibling Pair Families with ADHD

    ERIC Educational Resources Information Center

    Slaats-Willemse, Dorine; Swaab-Barneveld, Hanna; De Sonneville, Leo; Buitelaar, Jan

    2005-01-01

    Objective: To investigate familial clustering of executive functioning (i.e., response inhibition, fine visuomotor functioning, and attentional control) in attention-deficit/hyperactivity disorder (ADHD)-affected sibling pairs. Method: Fifty-two affected sibling pairs aged 6 to 18 years and diagnosed with ADHD according to DSM-IV performed the…

  2. 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 worl&dacute;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

  3. 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

  4. The liquid nitrogen fill level meter for the AGATA triple cluster detector

    NASA Astrophysics Data System (ADS)

    Lersch, Daniel; Pascovici, Gheorghe; Birkenbach, Benedikt; Bruyneel, Bart; Eberth, Jürgen; Hess, Herbert; Reiter, Peter; Wiens, Andreas; Georg Thomas, Heinz; Agata Collaboration

    2011-06-01

    A novel liquid nitrogen fill level meter has been put into operation for the all-position dewar of the triple cluster detector of the Advanced GAmma Tracking Array. The new device is based on a capacitance measurement between a metallic cylindrical tube inside the dewar and the inner wall of the cryostat. The fill level dependent capacitance is converted by a C/ V-transducer into a DC voltage signal. Direct monitoring of the LN 2 level inside the detector dewar has been performed with several AGATA detectors at various inclinations and rotation angles of the detector axis. The time-dependent LN 2 consumption is an additional quantity used to survey the status of the cryostat. Supplementary results are the investigations of the LN 2 consumption and the heat loss of the detector during different modes of operation.

  5. A Minimal Nitrogen Fixation Gene Cluster from Paenibacillus sp. WLY78 Enables Expression of Active Nitrogenase in Escherichia coli

    PubMed Central

    Zhao, Dehua; Liu, Xiaomeng; Zhang, Bo; Xie, Jianbo; Hong, Yuanyuan; Li, Pengfei; Chen, Sanfeng; Dixon, Ray; Li, Jilun

    2013-01-01

    Most biological nitrogen fixation is catalyzed by molybdenum-dependent nitrogenase, an enzyme complex comprising two component proteins that contains three different metalloclusters. Diazotrophs contain a common core of nitrogen fixation nif genes that encode the structural subunits of the enzyme and components required to synthesize the metalloclusters. However, the complement of nif genes required to enable diazotrophic growth varies significantly amongst nitrogen fixing bacteria and archaea. In this study, we identified a minimal nif gene cluster consisting of nine nif genes in the genome of Paenibacillus sp. WLY78, a gram-positive, facultative anaerobe isolated from the rhizosphere of bamboo. We demonstrate that the nif genes in this organism are organized as an operon comprising nifB, nifH, nifD, nifK, nifE, nifN, nifX, hesA and nifV and that the nif cluster is under the control of a σ70 (σA)-dependent promoter located upstream of nifB. To investigate genetic requirements for diazotrophy, we transferred the Paenibacillus nif cluster to Escherichia coli. The minimal nif gene cluster enables synthesis of catalytically active nitrogenase in this host, when expressed either from the native nifB promoter or from the T7 promoter. Deletion analysis indicates that in addition to the core nif genes, hesA plays an important role in nitrogen fixation and is responsive to the availability of molybdenum. Whereas nif transcription in Paenibacillus is regulated in response to nitrogen availability and by the external oxygen concentration, transcription from the nifB promoter is constitutive in E. coli, indicating that negative regulation of nif transcription is bypassed in the heterologous host. This study demonstrates the potential for engineering nitrogen fixation in a non-nitrogen fixing organism with a minimum set of nine nif genes. PMID:24146630

  6. COIL power extraction enhanced by reducing/eliminating iodine clusters in a high Mach number nitrogen mixing nozzle

    NASA Astrophysics Data System (ADS)

    Marshall, J.; Healey, K.; Croker, B.; Kendrick, K.; Yang, T. T.; Hsia, Y. C.; Dickerson, R. A.; Forman, L.

    2006-02-01

    Heterogeneous iodine cluster formation has been identified as the responsible factor resulting in large iodine titration requirements for Boeing's first high Mach number nitrogen ejector nozzle. A solution employing geometrically produced aerodynamic heating in the flow was envisioned to break up these clusters. Horizontal and vertical wire arrays (cluster busters) placed downstream of the nozzle exit plane (NEP) have been shown to significantly reduce the optimal iodine titration and to greatly improve the power extraction efficiency of the Chemical Oxygen-Iodine Laser utilizing this first generation ejector nozzle.

  7. The chemistry of nitrogen oxides on small size-selected cobalt clusters, Co{sub n}{sup +}

    SciTech Connect

    Anderson, Marie L.; Lacz, Agnieszka; Drewello, Thomas; Derrick, Peter J.; Woodruff, D. Phil; Mackenzie, Stuart R.

    2009-02-14

    Fourier transform ion cyclotron resonance mass spectrometry has been employed to study the reactions of gas-phase cationic cobalt clusters, Co{sub n}{sup +} (n=4-30), with nitric oxide, NO, and nitrous oxide, N{sub 2}O, under single collision conditions. Isolation of the initial cluster permits detailed investigation of fragmentation channels which characterize the reactions of all but the largest clusters studied. In reaction with N{sub 2}O, most clusters generate the monoxides Co{sub n}O{sup +} without fragmentation, cobalt atom loss accompanying only subsequent reactions. By contrast, chemisorption of even a single NO molecule is accompanied by fragmentation of the cluster. The measured rate coefficients for the Co{sub n}{sup +}+N{sub 2}O reaction as a function of cluster size are significantly smaller than those calculated using the surface charge capture model, while for NO the rates are comparable. The reactions have been studied under high coverage conditions by storing clusters for extended periods to permit multiple reactions to occur. This leads to interesting chemistry on the surface of the cluster resulting in the formation of stable oxide clusters and/or the decomposition of nitric oxide on the cluster with the resulting loss of molecular nitrogen.

  8. Atomic-scale magnetometry of distant nuclear spin clusters via nitrogen-vacancy spin in diamond.

    PubMed

    Zhao, Nan; Hu, Jian-Liang; Ho, Sai-Wah; Wan, Jones T K; Liu, R B

    2011-04-01

    The detection of single nuclear spins is an important goal in magnetic resonance spectroscopy. Optically detected magnetic resonance can detect single nuclear spins that are strongly coupled to an electron spin, but the detection of distant nuclear spins that are only weakly coupled to the electron spin has not been considered feasible. Here, using the nitrogen-vacancy centre in diamond as a model system, we numerically demonstrate that it is possible to detect two or more distant nuclear spins that are weakly coupled to a centre electron spin if these nuclear spins are strongly bonded to each other in a cluster. This cluster will stand out from other nuclear spins by virtue of characteristic oscillations imprinted onto the electron spin decoherence profile, which become pronounced under dynamical decoupling control. Under many-pulse dynamical decoupling, the centre electron spin coherence can be used to measure nuclear magnetic resonances of single molecules. This atomic-scale magnetometry should improve the performance of magnetic resonance spectroscopy for applications in chemical, biological, medical and materials research, and could also have applications in solid-state quantum computing. PMID:21358646

  9. 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

  10. Cysteine 295 indirectly affects Ni coordination of carbon monoxide dehydrogenase-II C-cluster

    SciTech Connect

    Inoue, Takahiro; Takao, Kyosuke; Yoshida, Takashi; Wada, Kei; Daifuku, Takashi; Yoneda, Yasuko; Fukuyama, Keiichi; Sako, Yoshihiko

    2013-11-08

    Highlights: •CODH-II harbors a unique [Ni-Fe-S] cluster. •We substituted the ligand residues of Cys{sup 295} and His{sup 261}. •Dramatic decreases in Ni content upon substitutions were observed. •All substitutions did not affect Fe-S clusters assembly. •CO oxidation activity was decreased by the substitutions. -- Abstract: A unique [Ni–Fe–S] cluster (C-cluster) constitutes the active center of Ni-containing carbon monoxide dehydrogenases (CODHs). His{sup 261}, which coordinates one of the Fe atoms with Cys{sup 295}, is suggested to be the only residue required for Ni coordination in the C-cluster. To evaluate the role of Cys{sup 295}, we constructed CODH-II variants. Ala substitution for the Cys{sup 295} substitution resulted in the decrease of Ni content and didn’t result in major change of Fe content. In addition, the substitution had no effect on the ability to assemble a full complement of [Fe–S] clusters. This strongly suggests Cys{sup 295} indirectly and His{sup 261} together affect Ni-coordination in the C-cluster.

  11. Nitrogen abundances and multiple stellar populations in the globular clusters of the Fornax dSph

    SciTech Connect

    Larsen, Søren S.; Strader, Jay

    2014-12-10

    We use measurements of nitrogen abundances in red giants to search for multiple stellar populations in the four most metal-poor globular clusters (GCs) in the Fornax dwarf spheroidal galaxy (Fornax 1, 2, 3, and 5). New imaging in the F343N filter, obtained with the Wide Field Camera 3 on the Hubble Space Telescope, is combined with archival F555W and F814W observations to determine the strength of the NH band near 3370 Å. After accounting for observational errors, the spread in the F343N-F555W colors of red giants in the Fornax GCs is similar to that in M15 and corresponds to an abundance range of Δ[N/Fe] ∼ 2 dex, as observed also in several Galactic GCs. The spread in F555W-F814W is, instead, fully accounted for by observational errors. The stars with the reddest F343N-F555W colors (indicative of N-enhanced composition) have more centrally concentrated radial distributions in all four clusters, although the difference is not highly statistically significant within any individual cluster. From double-Gaussian fits to the color distributions, we find roughly equal numbers of 'N-normal' and 'N-enhanced' stars (formally ∼40% N-normal stars in Fornax 1, 3, and 5 and ∼60% in Fornax 2). We conclude that GC formation, in particular, regarding the processes responsible for the origin of multiple stellar populations, appears to have operated similarly in the Milky Way and in the Fornax dSph. Combined with the high ratio of metal-poor GCs to field stars in the Fornax dSph, this places an important constraint on scenarios for the origin of multiple stellar populations in GCs.

  12. 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.

  13. Nitrogen and phosphorus additions negatively affect tree species diversity in tropical forest regrowth trajectories.

    PubMed

    Siddique, Ilyas; Vieira, Ima Célia Guimarães; Schmidt, Susanne; Lamb, David; Carvalho, Cláudio José Reis; Figueiredo, Ricardo de Oliveira; Blomberg, Simon; Davidson, Eric A

    2010-07-01

    Nutrient enrichment is increasingly affecting many tropical ecosystems, but there is no information on how this affects tree biodiversity. To examine dynamics in vegetation structure and tree species biomass and diversity, we annually remeasured tree species before and for six years after repeated additions of nitrogen (N) and phosphorus (P) in permanent plots of abandoned pasture in Amazonia. Nitrogen and, to a lesser extent, phosphorus addition shifted growth among woody species. Nitrogen stimulated growth of two common pioneer tree species and one common tree species adaptable to both high- and low-light environments, while P stimulated growth only of the dominant pioneer tree Rollinia exsucca (Annonaceae). Overall, N or P addition reduced tree assemblage evenness and delayed tree species accrual over time, likely due to competitive monopolization of other resources by the few tree species responding to nutrient enrichment with enhanced establishment and/or growth rates. Absolute tree growth rates were elevated for two years after nutrient addition. However, nutrient-induced shifts in relative tree species growth and reduced assemblage evenness persisted for more than three years after nutrient addition, favoring two nutrient-responsive pioneers and one early-secondary tree species. Surprisingly, N + P effects on tree biomass and species diversity were consistently weaker than N-only and P-only effects, because grass biomass increased dramatically in response to N + P addition. The resulting intensified competition probably prevented an expected positive N + P synergy in the tree assemblage. Thus, N or P enrichment may favor unknown tree functional response types, reduce the diversity of coexisting species, and delay species accrual during structurally and functionally complex tropical rainforest secondary succession. PMID:20715634

  14. Too Little, Too Late: How the Tidal Evolution of Hot Jupiters Affects Transit Surveys of Clusters

    NASA Technical Reports Server (NTRS)

    Debes, John H.; Jackson, Brian

    2010-01-01

    The tidal evolution of hot Jupiters may change the efficiency of transit surveys of stellar clusters. The orbital decay that hot Jupiters suffer may result in their destruction, leaving fewer transiting planets in older clusters. We calculate the impact tidal evolution has for different assumed stellar populations, including that of 47 Tuc, a globular cluster that was the focus of an intense HST search for transits. We find that in older clusters one expects to detect fewer transiting planets by a factor of two for surveys sensitive to Jupiter-like planets in orbits out to 0.5 AU, and up to a factor of 25 for surveys sensitive to Jupiter-like planets in orbits out to 0.08 AU. Additionally, tidal evolution affects the distribution of transiting planets as a function of semi-major axis, producing larger orbital period gaps for transiting planets as the age of the cluster increases. Tidal evolution can explain the lack of detected exoplanets in 47 Tuc without invoking other mechanisms. Four open clusters residing within the Kepler fields of view have ages that span 0.4-8 Gyr-if Kepler can observe a significant number of planets in these clusters, it will provide key tests for our tidal evolution hypothesis. Finally, our results suggest that observers wishing to discover transiting planets in clusters must have sufficient accuracy to detect lower mass planets, search larger numbers of cluster members, or have longer observation windows to be confident that a significant number of transits will occur for a population of stars.

  15. 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...

  16. 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.

  17. 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

  18. Ring opening of strained-ring heterocycles containing nitrogen by an osmium cluster complex

    SciTech Connect

    Adams, R.D.; Chen, Gong

    1992-11-01

    The osmium cluster complex Os{sub 3}(CO){sub 10}({mu}-NCH{sub 2}CH{sub 2}CH{sub 2})({mu}-H) (1) was obtained in 34% yield from the reaction of Os{sub 3}(CO){sub 10}(NCMe){sub 2} with azetidine. Complex 1 was characterized crystallographically and shown to contain a four-membered NCH{sub 2}CH{sub 2}CH{sub 2} ring bridging two of the metal atoms via the nitrogen atom. When heated to 125{degrees}C, 1 was transformed to the new complex Os{sub 3}(CO){sub 10}[{mu}-N=C(H)Et]({mu}-H) (2; 27% yield) by an opening of the four-membered ring and a hydrogen shift. Crystal data: for 1, space group P2{sub 1}/c, a = 8.793 (2) A, b = 16.265 (2) A, c = 13.766 (4) A, {Beta} = 110.56 (1){degrees}, Z = 4, 1872 reflections, R = 0.039; for 2, space group P1, a = 92.73 (2){degrees}, {Beta} = 99.03 (2){degrees}, {gamma} = 81.52 (2){degrees}, Z = 6, 4862 reflections, R = 0.024. 16 refs. 2 figs.

  19. Receptor clustering affects signal transduction at the membrane level in the reaction-limited regime

    NASA Astrophysics Data System (ADS)

    Caré, Bertrand R.; Soula, Hédi A.

    2013-01-01

    Many types of membrane receptors are found to be organized as clusters on the cell surface. We investigate the potential effect of such receptor clustering on the intracellular signal transduction stage. We consider a canonical pathway with a membrane receptor (R) activating a membrane-bound intracellular relay protein (G). We use Monte Carlo simulations to recreate biochemical reactions using different receptor spatial distributions and explore the dynamics of the signal transduction. Results show that activation of G by R is severely impaired by R clustering, leading to an apparent blunted biological effect compared to control. Paradoxically, this clustering decreases the half maximal effective dose (ED50) of the transduction stage, increasing the apparent affinity. We study an example of inter-receptor interaction in order to account for possible compensatory effects of clustering and observe the parameter range in which such interactions slightly counterbalance the loss of activation of G. The membrane receptors’ spatial distribution affects the internal stages of signal amplification, suggesting a functional role for membrane domains and receptor clustering independently of proximity-induced receptor-receptor interactions.

  20. 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. PMID:26106086

  1. 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

  2. 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%.

  3. Use of Nitrogen-15 Isotope Method in Soils and Ground Water to Determine Potential Nitrogen Sources Affecting a Municipal Water Supply in Kansas, USA

    NASA Astrophysics Data System (ADS)

    Townsend, M. A.; Macko, S. A.

    2004-12-01

    Nitrate-N concentrations have increased to greater than 10 mg/L in a municipal water supply in western Kansas from 1995 to 2002. A study was done by the Kansas Geological Survey using the nitrogen-15 natural abundance isotope method to determine potential sources for the increasing nitrate concentrations. Preliminary results of the isotope analyses on water samples suggest that animal waste and/or denitrification enrichment has affected the water supply. Soil samples from areas near the wells that were not treated with manure show a general increase of nitrogen-15 signature (+9 to +15 \\permil) to a depth of 5 m. Soils are silt loams with measurable carbonate (0.8 to 2 % by weight) in the profile, which may permit volatilization enrichment to occur in the soil profile. Wells in the area range from 11 to 20 m in alluvial deposits with depth to water at approximately 9 m). Nitrate-N values range from 8 to 26 mg/L. Nitrogen-15 values range from (+17 to +28 \\permil) with no obvious source of animal waste near the well sites. There are potential nearby long-term sources of animal waste - an abandoned sewage treatment plant and an agricultural testing farm. One well has a reducing chemistry with a nitrate value of 0.9 mg/L and a nitrogen-15 value of +17 \\permil suggesting that alluvial sediment variation also has an impact on the water quality in the study area. The other wells show values of nitrate and nitrogen-15 that are much greater than the associated soils. The use of nitrogen-15 alone permited limited evaluation of sources of nitrate to ground water particularly in areas with carbonate in the soils. Use of oxygen-18 on nitrate will permit the delineation of the processes affecting the nitrogen in the soil profile and determination of the probable sources and the processes that have affected the nitrogen in the ground water. Final results of the nitrogen-15 and oxygen-18 analyses will be presented.

  4. Affective Dispositions and PTSD Symptom Clusters in Female Interpersonal Trauma Survivors.

    PubMed

    Brown, Wilson J; Bruce, Steven E; Buchholz, Katherine R; Artime, Tiffany M; Hu, Emily; Sheline, Yvette I

    2016-02-01

    Interpersonal trauma (IPT) against women can have dire psychological consequences including persistent maladaptive changes in the subjective experience of affect. Contemporary literature has firmly established heightened negative affect (NA) as a risk and maintenance factor for posttraumatic stress disorder (PTSD). However, the relationship between NA and PTSD symptoms is not well understood within IPT survivors, the majority of whom are female, as much of this research has focused on combat veterans. In addition, the connection between positive affect (PA) and PTSD symptoms has yet to be examined. With increased emphasis on "negative alterations in cognitions and mood . . ." as an independent symptom cluster of PTSD in the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5), understanding the relationship between self-reported affectivity and the classic PTSD symptom clusters may be increasingly useful in differentiating symptom presentations of trauma-related psychopathology. The current study directly compared self-reported trait NA and PA with total severity and frequency cluster scores from the Clinician-Administered PTSD Scale (CAPS) in 54 female survivors of IPT who met criteria for PTSD. Results identify NA (but not PA) as a consistent predictor of total PTSD symptoms and, specifically, re-experiencing symptoms. PMID:25389192

  5. 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. PMID:25155758

  6. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2004-01-01

    Ammonia is the principal source of fixed nitrogen. It was produced by 17 companies at 34 plants in the United States during 2003. Fifty-three 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.

  7. 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 ...

  8. 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.

  9. Macronutrient content of a hypoenergy diet affects nitrogen retention and muscle function in weight lifters.

    PubMed

    Walberg, J L; Leidy, M K; Sturgill, D J; Hinkle, D E; Ritchey, S J; Sebolt, D R

    1988-08-01

    Weight lifters (WL) attempt to achieve a low body fat while maintaining fat free mass (FFM) and muscle function. Body composition and isometric muscular endurance were tested in 19 experienced male WL at the end of a weight maintenance and exercise routine standardization week. The subjects were assigned to either a control (C), moderate-protein (0.8 g.kg-1.d-1), high-carbohydrate hypoenergy diet (MP/HC), or high-protein (1.6 g.kg-1.d-1), moderate-carbohydrate hypoenergy diet (HP/MC). Both hypoenergy diets provided 75.3 kJ (18 kcal).kg-1.d-1. Apparent nitrogen balance (NBAL) was assessed using nitrogen in the diet, urine, and sweat. Body fat and FFM loss via hydrostatic weighing were not different between the hypoenergy groups. However, lean body mass (LBM) change as assessed by NBAL showed that the MP/HC group had an average negative NBAL of -3.19 g.d-1 while the HP/MC group had a positive NBAL of 4.13 g.d-1. Macronutrient mix did not affect biceps endurance, but quadriceps endurance declined for the HP/MC group during the experimental week. In conclusion, a hypoenergy diet providing twice the RDA for protein was more effective in retaining body protein in WL than a diet with higher carbohydrate but the RDA for protein. However, the lower carbohydrate of this diet contributed to reduced muscular endurance in these athletes. PMID:3182156

  10. 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. PMID:27380366

  11. 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

  12. 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. PMID:23479119

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

    PubMed

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

    2016-07-01

    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

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

    PubMed

    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

  15. 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

  16. Identification of the local vibrational modes of small nitrogen clusters in dilute GaAsN

    NASA Astrophysics Data System (ADS)

    Carvalho, A.; Barker, S. J.; Jones, R.; Williams, R. S.; Ashwin, M. J.; Newman, R. C.; Stavrinou, P. N.; Parry, G.; Jones, T. S.; Öberg, S.; Briddon, P. R.

    2007-12-01

    Ultra-high-resolution infra-red local vibrational mode (IR LVM) spectroscopy measurements together with density-functional calculations have been used to identify the signatures of close substitutional nitrogen ( NAs) pairs in GaAs1-xNx alloys with concentrations of x<0.025. We show that the presence of sub-peaks close to the NAs absorption band can be attributed to nitrogen pairs up to fourth neighbor position. Additionally, we suggest that the nitrogen pairs which give rise to the deepest levels below the conduction band edge are the first to be removed upon annealing.

  17. Severe dietary lysine restriction affects growth and body composition and hepatic gene expression for nitrogen metabolism in growing rats.

    PubMed

    Kim, J; Lee, K S; Kwon, D-H; Bong, J J; Jeong, J Y; Nam, Y S; Lee, M S; Liu, X; Baik, M

    2014-02-01

    Dietary lysine restriction may differentially affect body growth and lipid and nitrogen metabolism, depending on the degree of lysine restriction. This study was conducted to examine the effect of dietary lysine restriction on growth and lipid and nitrogen metabolism with two different degree of lysine restriction. Isocaloric amino acid-defined diets containing 1.4% lysine (adequate), 0.70% lysine (50% moderate lysine restriction) and 0.35% lysine (75% severe lysine restriction) were fed from the age of 52 to 77 days for 25 days in male Sprague-Dawley rats. The 75% severe lysine restriction increased (p < 0.05) food intake, but retarded (p < 0.05) growth, increased (p < 0.05) liver and muscle lipid contents and abdominal fat accumulation, increased (p < 0.05) blood urea nitrogen levels and mRNA levels of the serine-synthesizing 3-phosphoglycerate dehydrogenase gene, but decreased (p < 0.05) urea cycle arginase gene mRNA levels. In contrast, the 50% lysine restriction did not significantly (p > 0.05) affect body growth and lipid and nitrogen metabolism. Our results demonstrate that severe 75% lysine restriction has detrimental effects on body growth and deregulate lipid and nitrogen metabolism. PMID:23441935

  18. 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

  19. Elevated temperature differently affects foliar nitrogen partitioning in seedlings of diverse Douglas fir provenances.

    PubMed

    Du, Baoguo; Jansen, Kirstin; Junker, Laura Verena; Eiblmeier, Monika; Kreuzwieser, Jürgen; Gessler, Arthur; Ensminger, Ingo; Rennenberg, Heinz

    2014-10-01

    Global climate change causes an increase in ambient air temperature, a major environmental factor influencing plant physiology and growth that already has been perceived at the regional scale and is expected to become even more severe in the future. In the present study, we investigated the effect of elevated ambient air temperature on the nitrogen metabolism of two interior provenances of Douglas fir (Pseudotsuga menziesii var. glauca) originating from contrasting habitats, namely the provenances Monte Creek (MC) from a drier environment and Pend Oreille (PO) from a more humid environment. Three- to four-year-old seedlings of the two provenances were grown for 3 months in controlled environments under either control temperature (day 20 °C, night 15 °C) or high temperature (HT, 30/25 °C) conditions. Total nitrogen (N), soluble protein, chlorophyll and total amino acid (TAA) contents as well as individual amino acid concentrations were determined in both current-year and previous-year needles. Our results show that the foliar total N contents of the two provenances were unaffected by HT. Arginine, lysine, proline, glutamate and glutamine were the most abundant amino acids, which together contributed ∼88% to the TAA pool of current- and previous-year needles. High temperature decreased the contents of most amino acids of the glutamate family (i.e., arginine, proline, ornithine and glutamine) in current-year needles. However, HT did not affect the concentrations of metabolites related to the photorespiratory pathway, such as [Formula: see text], glycine and serine. In general, current-year needles were considerably more sensitive to HT than previous-year needles. Moreover, provenance PO originating from a mesic environment showed stronger responses to HT than provenance MC. Our results indicate provenance-specific plasticity in the response of Douglas fir to growth temperature. Provenance-specific effects of elevated temperature on N-use efficiency suggest

  20. The Magea gene cluster regulates male germ cell apoptosis without affecting the fertility in mice.

    PubMed

    Hou, Siyuan; Xian, Li; Shi, Peiliang; Li, Chaojun; Lin, Zhaoyu; Gao, Xiang

    2016-01-01

    While apoptosis is essential for male germ cell development, improper activation of apoptosis in the testis can affect spermatogenesis and cause reproduction defects. Members of the MAGE-A (melanoma antigen family A) gene family are frequently clustered in mammalian genomes and are exclusively expressed in the testes of normal animals but abnormally activated in a wide variety of cancers. We investigated the potential roles of these genes in spermatogenesis by generating a mouse model with a 210-kb genomic deletion encompassing six members of the Magea gene cluster (Magea1, Magea2, Magea3, Magea5, Magea6 and Magea8). Male mice carrying the deletion displayed smaller testes from 2 months old with a marked increase in apoptotic germ cells in the first wave of spermatogenesis. Furthermore, we found that Magea genes prevented stress-induced spermatogenic apoptosis after N-ethyl-N-nitrosourea (ENU) treatment during the adult stage. Mechanistically, deletion of the Magea gene cluster resulted in a dramatic increase in apoptotic germ cells, predominantly spermatocytes, with activation of p53 and induction of Bax in the testes. These observations demonstrate that the Magea genes are crucial in maintaining normal testicular size and protecting germ cells from excessive apoptosis under genotoxic stress. PMID:27226137

  1. The Magea gene cluster regulates male germ cell apoptosis without affecting the fertility in mice

    PubMed Central

    Hou, Siyuan; Xian, Li; Shi, Peiliang; Li, Chaojun; Lin, Zhaoyu; Gao, Xiang

    2016-01-01

    While apoptosis is essential for male germ cell development, improper activation of apoptosis in the testis can affect spermatogenesis and cause reproduction defects. Members of the MAGE-A (melanoma antigen family A) gene family are frequently clustered in mammalian genomes and are exclusively expressed in the testes of normal animals but abnormally activated in a wide variety of cancers. We investigated the potential roles of these genes in spermatogenesis by generating a mouse model with a 210-kb genomic deletion encompassing six members of the Magea gene cluster (Magea1, Magea2, Magea3, Magea5, Magea6 and Magea8). Male mice carrying the deletion displayed smaller testes from 2 months old with a marked increase in apoptotic germ cells in the first wave of spermatogenesis. Furthermore, we found that Magea genes prevented stress-induced spermatogenic apoptosis after N-ethyl-N-nitrosourea (ENU) treatment during the adult stage. Mechanistically, deletion of the Magea gene cluster resulted in a dramatic increase in apoptotic germ cells, predominantly spermatocytes, with activation of p53 and induction of Bax in the testes. These observations demonstrate that the Magea genes are crucial in maintaining normal testicular size and protecting germ cells from excessive apoptosis under genotoxic stress. PMID:27226137

  2. The Relationship of Cancer Symptom Clusters to Depressive Affect in the Initial Phase of Palliative Radiation

    PubMed Central

    Francoeur, Richard Benoit

    2007-01-01

    Research on comorbidity across cancer symptoms, including pain, fatigue, and depression, could suggest if crossover effects from symptom-specific interventions are plausible. Secondary analyses were conducted on a survey of 268 cancer patients with recurrent disease from a northeastern U.S. city who were initiating palliative radiation for bone pain. Moderator regression analyses predicted variation in depressive affect that could be attributed to symptom clusters. Patients self-reported difficulty controlling each physical symptom over the past month on a Likert scale and depressive symptoms on a validated depression measure (Center for Epidemiologic Studies-Depression [CES-D]) over the past week on a four-category scale. An index of depressive affect was based on items of negative and positive affect from the CES-D. In predicting depressive affect, synergistic interactions of pain with fever, fatigue, and weight loss suggest separate pathways involving pain. A similar interaction with fever occurs when nausea was tested in place of pain. Further, the interaction between pain and fatigue is similar in form to the interaction between difficulty breathing and fatigue (when sleep is not a problem). Follow-up to the latter interaction reveals: 1) additional moderation by hypertension and palliative radiation to the hip/pelvis; and 2) a similar cluster not involving hypertension when appetite problems and weight loss were tested in place of fatigue. The significance and form of these interactions are remarkably consistent. Similar sickness mechanisms could be generating: 1) pain and nausea during fever; 2) pain and fatigue during weight loss; and 3) pain and breathing difficulty when fatigue is pronounced. Crossover effects from symptom-specific interventions appear promising. PMID:15733806

  3. Nitrogen storage dynamics are affected by masting events in Fagus crenata.

    PubMed

    Han, Qingmin; Kabeya, Daisuke; Iio, Atsuhiro; Inagaki, Yoshiyuki; Kakubari, Yoshitaka

    2014-03-01

    It is generally assumed that the production of a large crop of seeds depletes stores of resources and that these take more than 1 year to replenish; this is accepted, theoretically, as the proximate mechanism of mast seeding (resource budget model). However, direct evidence of resource depletion in masting trees is very rare. Here, we trace seasonal and inter-annual variations in nitrogen (N) concentration and estimate the N storage pool of individuals after full masting of Fagus crenata in two stands. In 2005, a full masting year, the amount of N in fruit litter represented half of the N present in mature leaves in an old stand (age 190-260 years), and was about equivalent to the amount of N in mature leaves in a younger stand (age 83-84 years). Due to this additional burden, both tissue N concentration and individual N storage decreased in 2006; this was followed by significant replenishment in 2007, although a substantial N store remained even after full masting. These results indicate that internal storage may be important and that N may be the limiting factor for fruiting. In the 4 years following full masting, the old stand experienced two moderate masting events separated by 2 years, whilst trees in the younger stand did not fruit. This different fruiting behavior may be related to different "costs of reproduction" in the full masting year 2005, thus providing more evidence that N may limit fruiting. Compared to the non-fruiting stand, individuals in the fruiting stand exhibited an additional increase in N concentrations in roots early in the 2007 growing season, suggesting additional N uptake from the soil to supply resource demand. The enhanced uptake may alleviate the N storage depletion observed in the full masting year. This study suggests that masting affects N cycle dynamics in mature Fagus crenata and N may be one factor limiting fruiting. PMID:24221082

  4. 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.

  5. Salt tolerant plants increase nitrogen removal from biofiltration systems affected by saline stormwater.

    PubMed

    Szota, Christopher; Farrell, Claire; Livesley, Stephen J; Fletcher, Tim D

    2015-10-15

    Biofiltration systems are used in urban areas to reduce the concentration and load of nutrient pollutants and heavy metals entering waterways through stormwater runoff. Biofilters can, however be exposed to salt water, through intrusion of seawater in coastal areas which could decrease their ability to intercept and retain pollutants. We measured the effect of adding saline stormwater on pollutant removal by six monocotyledonous species with different levels of salt-tolerance. Carex appressa, Carex bichenoviana, Ficinia nodosa, Gahnia filum, Juncus kraussii and Juncus usitatus were exposed to six concentrations of saline stormwater, equivalent to electrical conductivity readings of: 0.09, 2.3, 5.5, 10.4, 20.0 and 37.6 mS cm(-1). Salt-sensitive species: C. appressa, C. bichenoviana and J. usitatus did not survive ≥10.4 mS cm(-1), removing their ability to take up nitrogen (N). Salt-tolerant species, such as F. nodosa and J. kraussii, maintained N-removal even at the highest salt concentration. However, their levels of water stress and stomatal conductance suggest that N-removal would not be sustained at concentrations ≥10.4 mS cm(-1). Increasing salt concentration indirectly increased phosphorus (P) removal, by converting dissolved forms of P to particulate forms which were retained by filter media. Salt concentrations ≥10 mS cm(-1) also reduced removal efficiency of zinc, manganese and cadmium, but increased removal of iron and lead, regardless of plant species. Our results suggest that biofiltration systems exposed to saline stormwater ≤10 mS cm(-1) can only maintain N-removal when planted with salt-tolerant species, while P removal and immobilisation of heavy metals is less affected by species selection. PMID:26150068

  6. Multifrequency electron spin-echo envelope modulation studies of nitrogen ligation to the manganese cluster of photosystem II.

    PubMed

    Yeagle, Gregory J; Gilchrist, M Lane; Walker, Lee M; Debus, Richard J; Britt, R David

    2008-03-27

    The CalEPR Center at UC-Davis (http://brittepr.ucdavis.edu) is equipped with five research grade electron paramagnetic resonance (EPR) instruments operating at various excitation frequencies between 8 and 130GHz. Of particular note for this RSC meeting are two pulsed EPR spectrometers working at the intermediate microwave frequencies of 31 and 35GHz. Previous lower frequency electron spin-echo envelope modulation (ESEEM) studies indicated that histidine nitrogen is electronically coupled to the Mn cluster in the S2 state of photosystem II (PSII). However, the amplitude and resolution of the spectra were relatively poor at these low frequencies, precluding any in-depth analysis of the electronic structure properties of this closely associated nitrogen nucleus. With the intermediate frequency instruments, we are much closer to the 'exact cancellation' limit, which optimizes ESEEM spectra for hyperfine-coupled nuclei such as 14N and 15N. Herein, we report the results from ESEEM studies of both 14N- and 15N-labelled PSII at these two frequencies. Spectral simulations were constrained by both isotope datasets at both frequencies, with a focus on high-resolution spectral examination of the histidine ligation to the Mn cluster in the S2 state. PMID:17954435

  7. 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

  8. Inhibition of nitrogen-fixing activity of the cyanobiont affects the localization of glutamine synthetase in hair cells of Azolla.

    PubMed

    Uheda, Eiji; Maejima, Kazuhiro

    2009-10-15

    In the Azolla-Anabaena association, the host plant Azolla efficiently incorporates and assimilates ammonium ions that are released from the nitrogen-fixing cyanobiont, probably via glutamine synthetase (GS; EC 6.3.1.2) in hair cells, which are specialized cells protruding into the leaf cavity. In order to clarify the regulatory mechanism underlying ammonium assimilation in the Azolla-Anabaena association, Azolla plants were grown under an argon environment (Ar), in which the nitrogen-fixing activity of the cyanobiont was inhibited specifically and completely. The localization of GS in hair cells was determined by immunoelectron microscopy and quantitative analysis of immunogold labeling. Azolla plants grew healthily under Ar when nitrogen sources, such as NO(3)(-) and NH(4)(+), were provided in the growth medium. Both the number of cyanobacterial cells per leaf and the heterocyst frequency of the plants under Ar were similar to those of plants in a nitrogen environment (N(2)). In hair cells of plants grown under Ar, regardless of the type of nitrogen source provided, only weak labeling of GS was observed in the cytoplasm and in chloroplasts. In contrast, in hair cells of plants grown under N(2), abundant labeling of GS was observed in both sites. These findings indicate that specific inhibition of the nitrogen-fixing activity of the cyanobiont affects the localization of GS isoenzymes. Ammonium fixed and released by the cyanobiont could stimulate GS synthesis in hair cells. Simultaneously, the abundant GS, probably GS1, in these cells, could assimilate ammonium rapidly. PMID:19464754

  9. 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

  10. 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

  11. Nitrogen Molecule Adsorption on Cationic Tantalum Clusters and Rhodium Clusters and Desorption from Their Nitride Clusters Studied by Thermal Desorption Spectrometry.

    PubMed

    Mafuné, Fumitaka; Tawaraya, Yuki; Kudoh, Satoshi

    2016-06-23

    Adsorption and desorption of N2 molecules onto cationic Ta and Rh clusters in the gas phase were investigated in the temperature range of 300-1000 K by using thermal desorption spectrometry in combination with density functional theory (DFT) calculations. For Ta6(+), the first N2 molecule was found to adsorb dissociatively, and it remained adsorbed when Ta6(+)N2 was heated to 1000 K. In contrast, the second and the subsequent N2 molecules adsorbed weakly as a molecular form and were released into the gas phase when heated to 600 K. The difference can be explained in terms of the activation barrier between the molecular and dissociative forms. On the other hand, when Ta clusters were generated in the presence of N2 gas by the laser ablation of a Ta rod, isomeric clusters, TanNm(+), having heat resistivity were formed. For Rh6(+), N2 adsorbed molecularly at 300 K and desorbed totally at 450 K. These results were consistent with the DFT calculations, indicating that the dissociative adsorption of N2 is endothermic. PMID:27276438

  12. 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...

  13. Nickel deficiency affects nitrogenous forms and urease activity in spring xylem sap of pecan

    Technology Transfer Automated Retrieval System (TEKTRAN)

    While nickel (Ni) deficiency occurs in certain agricultural crops, little is known regarding the influence of deficiency on metabolic or physiological processes. We studied the influence of Ni deficiency on the reduced-nitrogen (N) composition of early spring xylem sap of pecan [Carya illinoinensis...

  14. Nitrogen mineralization in soils amended with manure as affected by environmental conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrogen is the most deficient nutrient in most agricultural production systems; therefore, the economic sustainability of most crops is dependent on adequate supply. Consideration for N availability must be taken into account when incorporating manure into a cropping system’s management practice. S...

  15. 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 (...

  16. Maize stover and cob cell wall composition and ethanol potential as affected by nitrogen fertilization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize (Zea mays L.) stover and cobs are potential feedstock sources for cellulosic ethanol production. Nitrogen (N) fertilization is an important management decision that influences cellulosic biomass and grain production, but its effect on cell wall composition and subsequent cellulosic ethanol pro...

  17. Variable environment and market affects optimal nitrogen management in wheat and cattle production systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The average efficiency of fertilizer nitrogen (N) in grain production of cereals is about 33% worldwide, and a 1% increase in fertilizer N use efficiency (NUE) could annually save US producers 200-400 million US dollars. Process-based crop simulation models provide a unique opportunity to improve f...

  18. Nitrogen Fertilizer Affects the Severity of Anthracnose Crown Rot Disease of Greenhouse Grown Strawberries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The influence of nitrogen, phosphorus, and potassium on the severity of anthracnose crown rot was evaluated in three greenhouse studies. Strawberry plants were fertilized three times weekly with a modified Hoagland's Nutrient Solution containing the treatments and inoculated eight weeks after treat...

  19. 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 ‘...

  20. NITROGEN FERTILIZER RESPONSE OF INDIVIDUAL MAIZE PLANTS AS AFFECTED BY DAY OF EMERGENCE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recently developed crop canopy sensors are being evaluated for use in guiding variable rate applications of nitrogen (N) using ground-based equipment. These sensors output real-time information at 10 times a second, providing a sampling spatial resolution of approximately 22 cm for a ground based ap...

  1. 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...

  2. Nitrogen Source Affects Nitrous Oxide Emissions in a Strip-Tilled Continuous Corn Field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the effects of nitrogen (N) source on nitrous oxide (N2O) emissions from a strip-till (ST), irrigated continuous corn field in 2009 near Fort Collins, CO. Emissions were monitored from plots receiving six different inorganic N fertilizer sources (urea, ESN®1, SuperU®, UAN, UAN+Agrotain...

  3. Nitrogen Source Affects Nitrous Oxide Emissions from Irrigated No-Till Corn in Colorado (USA)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction Nitrogen fertilization is essential for optimizing corn yields and economic returns in irrigated cropping systems in the USA Central Great Plains area (Maddux and Halvorson, 2008). However, N application generally increases nitrous oxide (N2O) emissions from cropping systems (Mosier et...

  4. 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...

  5. 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

  6. 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. PMID:27368926

  7. How Environment Affects Star Formation: Tracing Activity in High Redshift Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Alberts, Stacey; Pope, A.; Brodwin, M.; Atlee, D. W.; Lin, Y.; Chary, R.; Dey, A.; Eisenhardt, P. R.; Gettings, D.; Gonzalez, A. H.; Jannuzi, B.; Mancone, C.; Moustakas, J.; Snyder, G. F.; Stanford, S. A.; Stern, D.; Weiner, B. J.; Zeimann, G.

    2014-01-01

    The emerging picture of the evolution of cluster galaxies indicates that the epoch of z>1 is a crucial period of active star formation and mass assembly in clusters. In this dissertation, I leverage a uniformly-selected cluster sample from the IRAC Shallow Cluster Survey (ISCS) with Herschel imaging to analyse the star formation (SF) activity in cluster galaxies over the past ten billion years. This analysis is two-fold: 1) using 274 clusters across the 9 square degree Bootes field, I perform a stacking analysis of mass-limited samples of cluster and field galaxies using wide-field Herschel observations over a long redshift baseline, z=0.3-1.5. I find that the average SF activity in cluster galaxies is evolving faster than in the field, with field-like SF in the cluster cores and enhanced SF activity in the cluster outskirts at z>1.2. By further breaking down my analysis by galaxy mass and type, I determine which mechanisms are capable of driving this evolution. 2) I use unique, deep Herschel imaging of 11 spectroscopically-confirmed clusters from z=1.1-1.8 to study the properties of individual infrared bright cluster galaxies as a function of redshift and cluster-centric radius. Combined with ancillary data, I determine the star formation, dust, and AGN properties of the most active cluster galaxies and tie the evolution of these properties back to the environment by comparing to field populations. By combining these two approaches, I constrain cluster galaxy properties during a pivotal epoch of dust-obscured star formation activity and mass assembly in some of the most extreme structures in the Universe.

  8. The interactions of nitrogen dioxide with graphene-stabilized Rh clusters: a DFT study.

    PubMed

    Furlan, Sara; Giannozzi, Paolo

    2013-10-14

    We study the interactions of NO2 gas molecules with Rh nanoparticles supported on graphene, using first-principles molecular dynamics in the Car-Parrinello scheme. The stability, morphology, adsorption energies of various models of Rhx nanoparticles (x = 1, 3, 10, 20) supported on graphene, and the binding of NO2 molecules to the Rh clusters, together with its effect on the graphene properties, are reported. Metastable flat structures anchored to the substrate that can bind NO2 to Rh via both N and O atoms are identified, with adsorption energies in the range 60-70 kcal per mole per molecule. PMID:23945990

  9. Two different approaches to the affective profiles model: median splits (variable-oriented) and cluster analysis (person-oriented).

    PubMed

    Garcia, Danilo; MacDonald, Shane; Archer, Trevor

    2015-01-01

    Background. The notion of the affective system as being composed of two dimensions led Archer and colleagues to the development of the affective profiles model. The model consists of four different profiles based on combinations of individuals' experience of high/low positive and negative affect: self-fulfilling, low affective, high affective, and self-destructive. During the past 10 years, an increasing number of studies have used this person-centered model as the backdrop for the investigation of between and within individual differences in ill-being and well-being. The most common approach to this profiling is by dividing individuals' scores of self-reported affect using the median of the population as reference for high/low splits. However, scores just-above and just-below the median might become high and low by arbitrariness, not by reality. Thus, it is plausible to criticize the validity of this variable-oriented approach. Our aim was to compare the median splits approach with a person-oriented approach, namely, cluster analysis. Method. The participants (N = 2, 225) were recruited through Amazons' Mechanical Turk and asked to self-report affect using the Positive Affect Negative Affect Schedule. We compared the profiles' homogeneity and Silhouette coefficients to discern differences in homogeneity and heterogeneity between approaches. We also conducted exact cell-wise analyses matching the profiles from both approaches and matching profiles and gender to investigate profiling agreement with respect to affectivity levels and affectivity and gender. All analyses were conducted using the ROPstat software. Results. The cluster approach (weighted average of cluster homogeneity coefficients = 0.62, Silhouette coefficients = 0.68) generated profiles with greater homogeneity and more distinctive from each other compared to the median splits approach (weighted average of cluster homogeneity coefficients = 0.75, Silhouette coefficients = 0.59). Most of the

  10. Two different approaches to the affective profiles model: median splits (variable-oriented) and cluster analysis (person-oriented)

    PubMed Central

    MacDonald, Shane; Archer, Trevor

    2015-01-01

    Background. The notion of the affective system as being composed of two dimensions led Archer and colleagues to the development of the affective profiles model. The model consists of four different profiles based on combinations of individuals’ experience of high/low positive and negative affect: self-fulfilling, low affective, high affective, and self-destructive. During the past 10 years, an increasing number of studies have used this person-centered model as the backdrop for the investigation of between and within individual differences in ill-being and well-being. The most common approach to this profiling is by dividing individuals’ scores of self-reported affect using the median of the population as reference for high/low splits. However, scores just-above and just-below the median might become high and low by arbitrariness, not by reality. Thus, it is plausible to criticize the validity of this variable-oriented approach. Our aim was to compare the median splits approach with a person-oriented approach, namely, cluster analysis. Method. The participants (N = 2, 225) were recruited through Amazons’ Mechanical Turk and asked to self-report affect using the Positive Affect Negative Affect Schedule. We compared the profiles’ homogeneity and Silhouette coefficients to discern differences in homogeneity and heterogeneity between approaches. We also conducted exact cell-wise analyses matching the profiles from both approaches and matching profiles and gender to investigate profiling agreement with respect to affectivity levels and affectivity and gender. All analyses were conducted using the ROPstat software. Results. The cluster approach (weighted average of cluster homogeneity coefficients = 0.62, Silhouette coefficients = 0.68) generated profiles with greater homogeneity and more distinctive from each other compared to the median splits approach (weighted average of cluster homogeneity coefficients = 0.75, Silhouette coefficients = 0.59). Most of the

  11. 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

  12. Hot Ductility Behaviors in the Weld Heat-Affected Zone of Nitrogen-Alloyed Fe-18Cr-10Mn Austenitic Stainless Steels

    NASA Astrophysics Data System (ADS)

    Moon, Joonoh; Lee, Tae-Ho; Hong, Hyun-Uk

    2015-04-01

    Hot ductility behaviors in the weld heat-affected zone (HAZ) of nitrogen-alloyed Fe-18Cr-10Mn austenitic stainless steels with different nitrogen contents were evaluated through hot tension tests using Gleeble simulator. The results of Gleeble simulations indicated that hot ductility in the HAZs deteriorated due to the formation of δ-ferrite and intergranular Cr2N particles. In addition, the amount of hot ductility degradation was strongly affected by the fraction of δ-ferrite.

  13. Carbon and nitrogen abundances of stellar populations in the globular cluster M 2

    NASA Astrophysics Data System (ADS)

    Lardo, C.; Pancino, E.; Mucciarelli, A.; Milone, A. P.

    2012-12-01

    We present CH and CN index analysis and C and N abundance calculations based on the low-resolution blue spectra of red giant branch (RGB) stars in the Galactic globular cluster NGC 7089 (M 2). Our main goal is to investigate the C-N anticorrelation for this intermediate metallicity cluster. The data were collected with DOLORES, the multiobject, low-resolution facility at the Telescopio Nazionale Galileo. We first looked for CH and CN band strength variations and bimodalities in a sample of RGB stars with 17.5 ≤ V ≤ 14.5. Thus we derived C and N abundances under LTE assumption by comparing observed spectra with synthetic models from the spectral features at 4300 Å (G-band) and at ~3883 Å (CN). Spectroscopic data were coupled with UV photometry obtained during the spectroscopic run. We found a considerable star-to-star variation in both A(C) and A(N) at all luminosities for our sample of 35 targets. These abundances appear to be anticorrelated, with a hint of bimodality in the C content for stars with luminosities below the RBG bump (V ~ 15.7), while the range of variations in N abundances is very large and spans almost ~2 dex. We find additional C depletion as the stars evolve off the RGB bump, in fairly good agreement with theoretical predictions for metal-poor stars in the course of normal stellar evolution. We isolated two groups with N-rich and N-poor stars and found that N abundance variations correlate with the (U - V) color in the DOLORES color-magnitude diagram (CMD). The V, (U - V) CMD for this cluster shows an additional RGB sequence, located at the red of the main RGB and amounting to a small fraction of the total giant population. We identified two CH stars detected in previous studies in our U,V images. These stars, which are both cluster members, fall on this redder sequence, suggesting that the anomalous RGB should have a peculiar chemical pattern. Unfortunately, no additional spectra were obtained for stars in this previously unknown RGB branch

  14. Nitrogen Availability for Sugarbeet affected by Tillage System and Sprinkler Irrigation Method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Strip tillage (ST) can reduce fuel and labor costs of sugarbeet (Beta vulgaris L.) production. Many shank-type ST implements band fertilizer below the seed without incorporating crop residue into the soil, potentially affecting N availability. Sprinkler irrigation method may also affect N availabili...

  15. AtNPF5.5, a nitrate transporter affecting nitrogen accumulation in Arabidopsis embryo

    PubMed Central

    Léran, Sophie; Garg, Bharti; Boursiac, Yann; Corratgé-Faillie, Claire; Brachet, Chantal; Tillard, Pascal; Gojon, Alain; Lacombe, Benoît

    2015-01-01

    Dipeptide (Leu-Leu) and nitrate transport activities of 26 Arabidopsis NPF (NRT1/PTR Family) proteins were screened in Saccharomyces cerevisiae and Xenopus laevis oocytes, respectively. Dipeptide transport activity has been confirmed for 2 already known dipeptide transporters (AtNPF8.1 and AtNPF8.3) but none of the other tested NPFs displays dipeptide transport. The nitrate transport screen resulted in the identification of two new nitrate transporters, AtNPF5.5 and AtNPF5.10. The localization of the mRNA coding for NPF5.5 demonstrates that it is the first NPF transporter reported to be expressed in Arabidopsis embryo. Two independent homozygous npf5.5 KO lines display reduced total nitrogen content in the embryo as compared to WT plants, demonstrating an effect of NPF5.5 function on the embryo nitrogen content. Finally, NPF5.5 gene produces two different transcripts (AtNPF5.5a and AtNPF5.5b) encoding proteins with different N-terminal ends. Both proteins are able to transport nitrate in xenopus oocytes. PMID:25608465

  16. Ruminal nitrogen metabolism in steers as affected by feed intake and dietary urea concentration

    SciTech Connect

    Firkins, J.L.; Berger, L.L.; Merchen, N.R.; Fahey, G.C. Jr.; Mulvaney, R.L.

    1987-11-01

    Four multiple-cannulated steers (340 kg) were used in a 4 x 4 Latin square design with a 2 x 2 factorial arrangement of treatments. Steers were fed a diet of 50% ground hay and 50% concentrate at two intakes (1.4 and 2.1% of BW), with urea and /sup 15/N-enriched ammonium sulfate infused continuously into the rumen at .4 or 1.2% of diet DM. Ratios of purines and diaminopimelic acid-N to N in fluid-associated and particulate-associated bacteria and in protozoa were similar among treatments but were lower for protozoa than for bacteria. Diaminopimelic acid-N:N was higher for fluid-associated vs. particulate-associated bacteria. Enrichment of /sup 15/N was similar between bacteria among treatments and was 30% lower for protozoa. Turnover rates of /sup 15/N in bacteria, NH/sub 3/N, and non-HN/sub 3/N pools were faster for steers infused with 1.2 than those infused with .4% urea, indicating less efficient usage of ammonia with higher urea. A method is described to estimate the proportion of duodenal nitrogen comprising bacterial and protozoal nitrogen.

  17. Does chronic nitrogen deposition during biomass growth affect atmospheric emissions from biomass burning?

    NASA Astrophysics Data System (ADS)

    Giordano, Michael R.; Chong, Joey; Weise, David R.; Asa-Awuku, Akua A.

    2016-03-01

    Chronic nitrogen deposition has measureable impacts on soil and plant health. We investigate burning emissions from biomass grown in areas of high and low NO x deposition. Gas and aerosol-phase emissions were measured as a function of photochemical aging in an environmental chamber at UC-Riverside. Though aerosol chemical speciation was not available, results indicate a systemic compositional difference between biomass grown in high and low deposition areas. Aerosol emissions from biomass grown in areas of high NO x deposition exhibit a lower volatility than biomass grown in a low deposition area. Furthermore, fuel elemental analysis, NO x emission rates, and aerosol particle number distributions differed significantly between the two sites. Despite the limited scale of fuels explored, there is strong evidence that the atmospheric emissions community must pay attention to the regional air quality of biomass fuels growth areas.

  18. 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. PMID:26406249

  19. 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

  20. 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

  1. Increased nitrogen deposition did not affect the composition and turnover of plant and microbial biomarkers in forest soil density fractions

    NASA Astrophysics Data System (ADS)

    Griepentrog, Marco; Bodé, Samuel; Boeckx, Pascal; Hagedorn, Frank; Wiesenberg, Guido L. B.; Schmidt, Michael W. I.

    2013-04-01

    Increased atmospheric nitrogen (N) deposition and elevated CO2 concentrations affect many forests and their ecosystem functions, including organic matter cycling in soils, the largest carbon pool of terrestrial ecosystems. However, it is still not clear how, and what the underlying mechanisms are. Specific molecules of plant and microbial origin (biomarkers) might respond differently to N deposition, depending on their internal N content. Microbial cell-wall-constituents with high-N content like amino sugars are reliable biomarkers to distinguish between fungal- and bacterial-derived organic residues. Individual lipids are plant-specific biomarkers that lack N in their molecular structure. Here, we tested the effects of elevated CO2 and increased N deposition on the dynamics of plant and microbial biomarkers by studying their composition and turnover in forest soil density fractions. Furthermore, we tested the hypothesis that these biomarkers respond differently to increased N deposition, depending on their internal N content. We used soil samples from a 4-year elevated CO2 and N deposition experiment in model forest ecosystems (open-top chambers), that were fumigated with ambient and 13C-depleted CO2 and treated with two levels of 15N-labeled fertilizer. Bulk soil was separated into free light fraction, occluded light fraction and heavy fraction by density fractionation and ultrasonic dispersion. The heavy fraction was further particle-size fractionated with 20 μm as a cut-off. We determined carbon and N concentrations and their isotopic compositions (δ13C, δ15N) within bulk soil and density fractions. Therein, we extracted and quantified individual amino sugars and lipids and conducted compound-specific stable-isotope-analysis using GC- and LC-IRMS. Results show that amino sugars were mainly stabilized in association with soil minerals. Especially bacterial amino sugars were preferentially associated with soil minerals, exemplified by a consistent decrease

  2. 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. PMID:26024252

  3. Nitrogen Addition as a Result of Long-Term Root Removal Affects Soil Organic Matter Dynamics

    NASA Astrophysics Data System (ADS)

    Crow, S. E.; Lajtha, K.

    2004-12-01

    A long-term field litter manipulation site was established in a mature coniferous forest stand at the H.J. Andrews Experimental Forest, OR, USA in 1997 in order to address how detrital inputs influence soil organic matter formation and accumulation. Soils at this site are Andisols and are characterized by high carbon (C) and low nitrogen (N) contents, due largely to the legacy of woody debris and extremely low atmospheric N deposition. Detrital treatments include trenching to remove roots, doubling wood and needle litter, and removing aboveground litter. In order to determine whether five years of detrital manipulation had altered organic matter quantity and lability at this site, soil from the top 0-5 cm of the A horizon was density fractionated to separate the labile light fraction (LF) from the more recalcitrant mineral soil in the heavy fraction (HF). Both density fractions and whole soils were incubated for one year in chambers designed such that repeated measurements of soil respiration and leachate chemistry could be made. Trenching resulted in the removal of labile root inputs from root exudates and turnover of fine roots and active mycorrhizal communities as well as an increase of available N by removing plant uptake. Since 1999, soil solution chemistry from tension lysimeters has shown greater total N and dissolved organic nitrogen (DON) flux and less dissolved organic carbon (DOC) flux to stream flow in the trenched plots relative to the other detrital treatments. C/N ratio and C content of both light and heavy fractions from the trenched plots were greater than other detrital treatments. In the lab incubation, over the course of a year C mineralization from these soils was suppressed. Cumulative DOC losses and CO2 efflux both were significantly less in soils from trenched plots than in other detrital treatments including controls. After day 150 of the incubation, leachates from the HF of plots with trenched treatments had a DOC/DON ratio significantly

  4. 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...

  5. Nitrogen supplementation does not affect level of an Alkaloid swainsonine in four locoweeds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Locoweeds are legumes that can be highly poisonous to livestock and wild animals. Locoweed toxicity depends on the association of a plant and a fungal endophyte which produces the alkaloid swainsonine (SWA); however, environmental factors affecting SWA synthesis are unknown. Additionally, locoweeds ...

  6. SOIL COMPACTION AND POULTRY LITTER EFFECTS ON FACTORS AFFECTING NITROGEN AVAILABILITY IN A CLAYPAN SOIL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil compaction may affect N mineralization and the subsequent fate of N in agroecosystems. Laboratory incubation and field experiments were conducted to determine the effects of surface soil compaction on soil N mineralization in a claypan soil amended with poultry litter (i.e., turkey excrement mi...

  7. 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...

  8. Fertilizer residence time affects nitrogen uptake efficiency and growth of sweet corn.

    PubMed

    Zotarelli, L; Scholberg, J M; Dukes, M D; Muñoz-Carpena, R

    2008-01-01

    Understanding plant N uptake dynamics is critical for increasing fertilizer N uptake efficiency (FUE) and minimize the risk of N leaching. The objective of this research was to determine the effect of residence time of N fertilizer on N uptake and FUE of sweet corn. Plants were grown in 25 L columns during the fall and spring to mimic short-term N uptake dynamics. Nitrogen was applied either 1, 3, or 7 d before a weekly leaching event, using KNO3 solution (total of 393 kg N ha(-1)). Residence times (tR) were tR-1, tR-3, and tR-7 d before weekly removal of residual soil N. Plant N uptake was calculated by comparing weekly N recovery from planted with non-planted columns. During the fall, N uptake values at 70 d after emergence were 59, 73, and 126 kg N ha(-1). During the spring, corresponding values were 54, 108, and 159 kg N ha(-1). A linear response of plant growth and yield to the tR was observed under cooler conditions, whereas a quadratic response occurred under warmer conditions. There was correlation between root length density and yield. It is concluded that increasing N fertilizer residence time, which is indicative of better irrigation practices, enhanced overall sweet corn growth, yield, N uptake, and FUE, consequently reduced the risk of N being leached below the root zone before complete N uptake. PMID:18453447

  9. A global analysis of fine root production as affected by soil nitrogen and phosphorus

    PubMed Central

    Yuan, Z. Y.; Chen, Han Y. H.

    2012-01-01

    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 CO2 emissions. PMID:22764168

  10. Glutamine synthetase mutations which affect expression of nitrogen fixation genes in Klebsiella pneumoniae.

    PubMed Central

    Ausubel, F M; Bird, S C; Durbin, K J; Janssen, K A; Margolskee, R F; Peskin, A P

    1979-01-01

    Previous studies have implicated glutamine synthetase (L-glutamate:ammonia ligase [adenosine diphosphate for-ing], EC 6.6.1.2) as a major controlling element of the nitrogen fixation (nif) genes in Klebsiella pneumoniae. We report here the isolation of a new class of K. pneumoniae mutants which exhibit altered patterns of nif and hut (histidine utlization) regulation. The expression of nif in these mutants, which were isolated as Gln+ (glutamine nonrequiring) revertants of a particular glnA mutation, is extremely sensitive to ammonia repression. These mutants have a Nif- Hut- phenotype at external ammonia concentrations at which wild-type strains are Nif+ Hut+. On the other hand, these mutants can be fully derepressed for nif at very low ammonia concentrations. We adopted the nomenclature "GlnR- (Nif- Hut-)" to facilitate discussion of the phenotype of these mutant strains. The mutations in these strains which confer the GlnR- phenotype map at or near glnA, the structural gene for glutamine synthetase. PMID:40960

  11. 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

  12. 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. PMID:27149150

  13. Do clusters of galaxies affect the spectrum of the microwave background?

    NASA Technical Reports Server (NTRS)

    Markevitch, M.; Blumenthal, G. R.; Forman, W.; Jones, C.; Suniaev, R. A.

    1991-01-01

    The distortion, averaged over the sky, due to the Compton scattering of background photons with electrons in the hot gas in clusters of galaxies is calculated. Using an existing sample of X-ray clusters, various values of the density parameter Omega, and plausible models for cluster evolution, Monte Carlo realizations of the microwave sky are generated. The spatial structure of these simulations shows a network of discrete sources whose properties can be a strong function of both evolution and Omega. The amount of spectral distortion in the models is greatest for models characterized by self-similar cluster evolution in an open universe and is within an order of magnitude of the current upper limits. Thus, improved observational sensitivity must inevitably detect some deviation from a blackbody spectrum.

  14. Particulate Organic Matter Affects Soil Nitrogen Mineralization under Two Crop Rotation Systems

    PubMed Central

    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. PMID:26647157

  15. 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. PMID:26647157

  16. Photosynthesis and photoprotection in coffee leaves is affected by nitrogen and light availabilities in winter conditions.

    PubMed

    Pompelli, Marcelo F; Martins, Samuel C V; Antunes, Werner C; Chaves, Agnaldo R M; DaMatta, Fábio M

    2010-09-01

    Coffee is native to shady environments but often grows better and produces higher yields without shade, though at the expense of high fertilization inputs, particularly nitrogen (N). Potted plants were grown under full sunlight and shade (50%) conditions and were fertilized with nutrient solutions containing either 0 or 23 mM N. Measurements were made in southeastern Brazil during winter conditions, when relatively low night temperatures and high diurnal insolation are common. Overall, the net carbon assimilation rate was quite low, which was associated with diffusive, rather than biochemical, constraints. N deficiency led to decreases in the concentrations of chlorophylls (Chl) and total carotenoids as well as in the Chl/N ratio. These conditions also led to qualitative changes in the carotenoid composition, e.g., increased antheraxanthin (A) and zeaxanthin (Z) pools on a Chl basis, particularly at high light, which was linked to increased thermal dissipation of absorbed light. The variable-to-maximum fluorescence ratio at predawn decreased with increasing A+Z pools and decreased linearly with decreasing N. We showed that this ratio was inadequate for assessing photoinhibition under N limitation. Expressed per unit mass, the activities of superoxide dismutase and glutathione reductase were not altered with the treatments. In contrast, ascorbate peroxidase activity was lower in low N plants, particularly under shade, whereas catalase activity was lower in shaded plants than in sun-grown plants, regardless of the N level. Glutamine synthetase activity was greater in sun-grown plants than in shaded individuals at a given N level and decreased with decreasing N application. Our results suggest that the photoprotective and antioxidant capacity per amount of photons absorbed was up-regulated by a low N supply; nevertheless, this capacity, regardless of the light conditions, was not enough to prevent oxidative damage, as judged from the increases in the H(2)O(2) and

  17. Coral Uptake of Inorganic Phosphorus and Nitrogen Negatively Affected by Simultaneous Changes in Temperature and pH

    PubMed Central

    Godinot, Claire; Houlbrèque, Fanny

    2011-01-01

    The effects of ocean acidification and elevated seawater temperature on coral calcification and photosynthesis have been extensively investigated over the last two decades, whereas they are still unknown on nutrient uptake, despite their importance for coral energetics. We therefore studied the separate and combined impacts of increases in temperature and pCO2 on phosphate, ammonium, and nitrate uptake rates by the scleractinian coral S. pistillata. Three experiments were performed, during 10 days i) at three pHT conditions (8.1, 7.8, and 7.5) and normal temperature (26°C), ii) at three temperature conditions (26°, 29°C, and 33°C) and normal pHT (8.1), and iii) at three pHT conditions (8.1, 7.8, and 7.5) and elevated temperature (33°C). After 10 days of incubation, corals had not bleached, as protein, chlorophyll, and zooxanthellae contents were the same in all treatments. However, photosynthetic rates significantly decreased at 33°C, and were further reduced for the pHT 7.5. The photosynthetic efficiency of PSII was only decreased by elevated temperature. Nutrient uptake rates were not affected by a change in pH alone. Conversely, elevated temperature (33°C) alone induced an increase in phosphate uptake but a severe decrease in nitrate and ammonium uptake rates, even leading to a release of nitrogen into seawater. Combination of high temperature (33°C) and low pHT (7.5) resulted in a significant decrease in phosphate and nitrate uptake rates compared to control corals (26°C, pHT = 8.1). These results indicate that both inorganic nitrogen and phosphorus metabolism may be negatively affected by the cumulative effects of ocean warming and acidification. PMID:21949839

  18. 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.

  19. 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

  20. 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

  1. Hypoxia Affects Nitrogen Uptake and Distribution in Young Poplar (Populus × canescens) Trees

    PubMed Central

    Liu, Bin; Rennenberg, Heinz; Kreuzwieser, Jürgen

    2015-01-01

    The present study with young poplar trees aimed at characterizing the effect of O2 shortage in the soil on net uptake of NO3- and NH4+ and the spatial distribution of the N taken up. Moreover, we assessed biomass increment as well as N status of the trees affected by O2 deficiency. For this purpose, an experiment was conducted in which hydroponically grown young poplar trees were exposed to hypoxic and normoxic (control) conditions for 14 days. 15N-labelled NO3- and NH4+ were used to elucidate N uptake and distribution of currently absorbed N and N allocation rates in the plants. Whereas shoot biomass was not affected by soil O2 deficiency, it significantly reduced root biomass and, consequently, the root-to-shoot ratio. Uptake of NO3- but not of NH4+ by the roots of the trees was severely impaired by hypoxia. As a consequence of reduced N uptake, the N content of all poplar tissues was significantly diminished. Under normoxic control conditions, the spatial distribution of currently absorbed N and N allocation rates differed depending on the N source. Whereas NO3- derived N was mainly transported to the younger parts of the shoot, particularly to the developing and young mature leaves, N derived from NH4+ was preferentially allocated to older parts of the shoot, mainly to wood and bark. Soil O2 deficiency enhanced this differential allocation pattern. From these results we assume that NO3- was assimilated in developing tissues and preferentially used to maintain growth and ensure plant survival under hypoxia, whereas NH4+ based N was used for biosynthesis of storage proteins in bark and wood of the trees. Still, further studies are needed to understand the mechanistic basis as well as the eco-physiological advantages of such differential allocation patterns. PMID:26308462

  2. A systematic review of factors affecting children's right to health in cluster randomized trials in Kenya.

    PubMed

    Oduwo, Elizabeth; Edwards, Sarah J L

    2014-01-01

    Following the South African case, Treatment Action Campaign and Others v Minister of Health and Others, the use of 'pilot' studies to investigate interventions already proven efficacious, offered free of charge to government, but confined by the government to a small part of the population, may violate children's right to health, and the negative duty on governments not to prevent access to treatment. The applicants challenged a government decision to offer Nevirapine in a few pilot sites when evidence showed Nevirapine significantly reduced HIV transmission rates and despite donor offers of a free supply. The government refused to expand access, arguing they needed to collect more information, and citing concerns about long-term hazards, side effects, resistance and inadequate infrastructure. The court ruled this violated children's right to health and asked the government to immediately expand access. Cluster randomized trials involving children are increasingly popular, and are often used to reduce 'contamination': the possibility that members of a cluster adopt behavior of other clusters. However, they raise unique issues insufficiently addressed in literature and ethical guidelines. This case provides additional crucial guidance, based on a common human rights framework, for the Kenyan government and other involved stakeholders. Children possess special rights, often represent a 'captive' group, and so motivate extra consideration. In a systematic review, we therefore investigated whether cluster trial designs are used to prevent or delay children's access to treatment in Kenya or otherwise inconsistently with children's right to health as outlined in the above case. Although we did not find state sponsored cluster trials, most had significant public sector involvement. Core obligations under children's right to health were inadequately addressed across trials. Few cluster trials reported rationale for cluster randomization, offered post- trial access or

  3. Microbial characterization of nitrification in a shallow, nitrogen-contaminated aquifer, Cape Cod, Massachusetts and detection of a novel cluster associated with nitrifying Betaproteobacteria.

    PubMed

    Miller, Daniel N; Smith, Richard L

    2009-01-26

    Groundwater nitrification is a poorly characterized process affecting the speciation and transport of nitrogen. Cores from two sites in a plume of contamination were examined using culture-based and molecular techniques targeting nitrification processes. The first site, located beneath a sewage effluent infiltration bed, received treated effluent containing O2 (>300 microM) and NH4+ (51-800 microM). The second site was 2.5 km down-gradient near the leading edge of the ammonium zone within the contaminant plume and featured vertical gradients of O2, NH4+, and NO3- (0-300, 0-500, and 100-200 microM with depth, respectively). Ammonia- and nitrite-oxidizers enumerated by the culture-based MPN method were low in abundance at both sites (1.8 to 350 g(-1) and 33 to 35,000 g(-1), respectively). Potential nitrifying activity measured in core material in the laboratory was also very low, requiring several weeks for products to accumulate. Molecular analysis of aquifer DNA (nested PCR followed by cloning and 16S rDNA sequencing) detected primarily sequences associated with the Nitrosospira genus throughout the cores at the down-gradient site and a smaller proportion from the Nitrosomonas genus in the deeper anoxic, NH4+ zone at the down-gradient site. Only a single Nitrosospira sequence was detected beneath the infiltration bed. Furthermore, the majority of Nitrosospira-associated sequences represent an unrecognized cluster. We conclude that an uncharacterized group associated with Nitrosospira dominate at the geochemically stable, down-gradient site, but found little evidence for Betaproteobacteria nitrifiers beneath the infiltration beds where geochemical conditions were more variable. PMID:19059672

  4. Microbial characterization of nitrification in a shallow, nitrogen-contaminated aquifer, Cape Cod, Massachusetts and detection of a novel cluster associated with nitrifying Betaproteobacteria

    USGS Publications Warehouse

    Miller, D.N.; Smith, R.L.

    2009-01-01

    Groundwater nitrification is a poorly characterized process affecting the speciation and transport of nitrogen. Cores from two sites in a plume of contamination were examined using culture-based and molecular techniques targeting nitrification processes. The first site, located beneath a sewage effluent infiltration bed, received treated effluent containing O2 (> 300????M) and NH4+ (51-800????M). The second site was 2.5??km down-gradient near the leading edge of the ammonium zone within the contaminant plume and featured vertical gradients of O2, NH4+, and NO3- (0-300, 0-500, and 100-200????M with depth, respectively). Ammonia- and nitrite-oxidizers enumerated by the culture-based MPN method were low in abundance at both sites (1.8 to 350??g- 1 and 33 to 35,000??g- 1, respectively). Potential nitrifying activity measured in core material in the laboratory was also very low, requiring several weeks for products to accumulate. Molecular analysis of aquifer DNA (nested PCR followed by cloning and 16S rDNA sequencing) detected primarily sequences associated with the Nitrosospira genus throughout the cores at the down-gradient site and a smaller proportion from the Nitrosomonas genus in the deeper anoxic, NH4+ zone at the down-gradient site. Only a single Nitrosospira sequence was detected beneath the infiltration bed. Furthermore, the majority of Nitrosospira-associated sequences represent an unrecognized cluster. We conclude that an uncharacterized group associated with Nitrosospira dominate at the geochemically stable, down-gradient site, but found little evidence for Betaproteobacteria nitrifiers beneath the infiltration beds where geochemical conditions were more variable.

  5. Microbial characterization of nitrification in a shallow, nitrogen-contaminated aquifer, Cape Cod, Massachusetts and detection of a novel cluster associated with nitrifying Betaproteobacteria

    NASA Astrophysics Data System (ADS)

    Miller, Daniel N.; Smith, Richard L.

    2009-01-01

    Groundwater nitrification is a poorly characterized process affecting the speciation and transport of nitrogen. Cores from two sites in a plume of contamination were examined using culture-based and molecular techniques targeting nitrification processes. The first site, located beneath a sewage effluent infiltration bed, received treated effluent containing O 2 (> 300 µM) and NH 4+ (51-800 µM). The second site was 2.5 km down-gradient near the leading edge of the ammonium zone within the contaminant plume and featured vertical gradients of O 2, NH 4+, and NO 3- (0-300, 0-500, and 100-200 µM with depth, respectively). Ammonia- and nitrite-oxidizers enumerated by the culture-based MPN method were low in abundance at both sites (1.8 to 350 g - 1 and 33 to 35,000 g - 1 , respectively). Potential nitrifying activity measured in core material in the laboratory was also very low, requiring several weeks for products to accumulate. Molecular analysis of aquifer DNA (nested PCR followed by cloning and 16S rDNA sequencing) detected primarily sequences associated with the Nitrosospira genus throughout the cores at the down-gradient site and a smaller proportion from the Nitrosomonas genus in the deeper anoxic, NH 4+ zone at the down-gradient site. Only a single Nitrosospira sequence was detected beneath the infiltration bed. Furthermore, the majority of Nitrosospira-associated sequences represent an unrecognized cluster. We conclude that an uncharacterized group associated with Nitrosospira dominate at the geochemically stable, down-gradient site, but found little evidence for Betaproteobacteria nitrifiers beneath the infiltration beds where geochemical conditions were more variable.

  6. 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

  7. Genome scan identifies a locus affecting gamma-globin expression in human beta-cluster YAC transgenic mice

    SciTech Connect

    Lin, S.D.; Cooper, P.; Fung, J.; Weier, H.U.G.; Rubin, E.M.

    2000-03-01

    Genetic factors affecting post-natal g-globin expression - a major modifier of the severity of both b-thalassemia and sickle cell anemia, have been difficult to study. This is especially so in mice, an organism lacking a globin gene with an expression pattern equivalent to that of human g-globin. To model the human b-cluster in mice, with the goal of screening for loci affecting human g-globin expression in vivo, we introduced a human b-globin cluster YAC transgene into the genome of FVB mice . The b-cluster contained a Greek hereditary persistence of fetal hemoglobin (HPFH) g allele resulting in postnatal expression of human g-globin in transgenic mice. The level of human g-globin for various F1 hybrids derived from crosses between the FVB transgenics and other inbred mouse strains was assessed. The g-globin level of the C3HeB/FVB transgenic mice was noted to be significantly elevated. To map genes affecting postnatal g-globin expression, a 20 centiMorgan (cM) genome scan of a C3HeB/F VB transgenics [prime] FVB backcross was performed, followed by high-resolution marker analysis of promising loci. From this analysis we mapped a locus within a 2.2 cM interval of mouse chromosome 1 at a LOD score of 4.2 that contributes 10.4% of variation in g-globin expression level. Combining transgenic modeling of the human b-globin gene cluster with quantitative trait analysis, we have identified and mapped a murine locus that impacts on human g-globin expression in vivo.

  8. 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

  9. Large-scale dynamics associated with clustering of extratropical cyclones affecting Western Europe

    NASA Astrophysics Data System (ADS)

    Pinto, Joaquim G.; Gómara, Iñigo; Masato, Giacomo; Dacre, Helen F.; Woollings, Tim; Caballero, Rodrigo

    2015-04-01

    Some recent winters in Western Europe have been characterized by the occurrence of multiple extratropical cyclones following a similar path. The occurrence of such cyclone clusters leads to large socio-economic impacts due to damaging winds, storm surges, and floods. Recent studies have statistically characterized the clustering of extratropical cyclones over the North Atlantic and Europe and hypothesized potential physical mechanisms responsible for their formation. Here we analyze 4 months characterized by multiple cyclones over Western Europe (February 1990, January 1993, December 1999, and January 2007). The evolution of the eddy driven jet stream, Rossby wave-breaking, and upstream/downstream cyclone development are investigated to infer the role of the large-scale flow and to determine if clustered cyclones are related to each other. Results suggest that optimal conditions for the occurrence of cyclone clusters are provided by a recurrent extension of an intensified eddy driven jet toward Western Europe lasting at least 1 week. Multiple Rossby wave-breaking occurrences on both the poleward and equatorward flanks of the jet contribute to the development of these anomalous large-scale conditions. The analysis of the daily weather charts reveals that upstream cyclone development (secondary cyclogenesis, where new cyclones are generated on the trailing fronts of mature cyclones) is strongly related to cyclone clustering, with multiple cyclones developing on a single jet streak. The present analysis permits a deeper understanding of the physical reasons leading to the occurrence of cyclone families over the North Atlantic, enabling a better estimation of the associated cumulative risk over Europe.

  10. Large-scale dynamics associated with clustering of extratropical cyclones affecting Western Europe

    NASA Astrophysics Data System (ADS)

    Pinto, Joaquim G.; Gómara, Iñigo; Masato, Giacomo; Dacre, Helen F.; Woollings, Tim; Caballero, Rodrigo

    2014-12-01

    Some recent winters in Western Europe have been characterized by the occurrence of multiple extratropical cyclones following a similar path. The occurrence of such cyclone clusters leads to large socio-economic impacts due to damaging winds, storm surges, and floods. Recent studies have statistically characterized the clustering of extratropical cyclones over the North Atlantic and Europe and hypothesized potential physical mechanisms responsible for their formation. Here we analyze 4 months characterized by multiple cyclones over Western Europe (February 1990, January 1993, December 1999, and January 2007). The evolution of the eddy driven jet stream, Rossby wave-breaking, and upstream/downstream cyclone development are investigated to infer the role of the large-scale flow and to determine if clustered cyclones are related to each other. Results suggest that optimal conditions for the occurrence of cyclone clusters are provided by a recurrent extension of an intensified eddy driven jet toward Western Europe lasting at least 1 week. Multiple Rossby wave-breaking occurrences on both the poleward and equatorward flanks of the jet contribute to the development of these anomalous large-scale conditions. The analysis of the daily weather charts reveals that upstream cyclone development (secondary cyclogenesis, where new cyclones are generated on the trailing fronts of mature cyclones) is strongly related to cyclone clustering, with multiple cyclones developing on a single jet streak. The present analysis permits a deeper understanding of the physical reasons leading to the occurrence of cyclone families over the North Atlantic, enabling a better estimation of the associated cumulative risk over Europe.

  11. 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.

  12. Microbial Characterization of Nitrification in a Shallow, Nitrogen-Contaminated Aquifer, Cape Cod, Massachusetts and Detection of a Novel Cluster Associated with Nitrifying Betaproteobacteria

    Technology Transfer Automated Retrieval System (TEKTRAN)

    : Groundwater nitrification is a poorly characterized process affecting the speciation and transport of nitrogen. Cores from two sites in a sewage-contaminated groundwater plume were examined for microbial and molecular evidence of nitrification processes. The first, located beneath a sewage effl...

  13. 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

  14. How nitrogen and sulphur addition, and a single drought event affect root phosphatase activity in Phalaris arundinacea.

    PubMed

    Robroek, Bjorn J M; Adema, Erwin B; Venterink, Harry Olde; Leonardson, Lars; Wassen, Martin J

    2009-03-15

    Conservation and restoration of fens and fen meadows often aim to reduce soil nutrients, mainly nitrogen (N) and phosphorus (P). The biogeochemistry of P has received much attention as P-enrichment is expected to negatively impact on species diversity in wetlands. It is known that N, sulphur (S) and hydrological conditions affect the biogeochemistry of P, yet their interactive effects on P-dynamics are largely unknown. Additionally, in Europe, climate change has been predicted to lead to increases in summer drought. We performed a greenhouse experiment to elucidate the interactive effects of N, S and a single drought event on the P-availability for Phalaris arundinacea. Additionally, the response of plant phosphatase activity to these factors was measured over the two year experimental period. In contrast to results from earlier experiments, our treatments hardly affected soil P-availability. This may be explained by the higher pH in our soils, hampering the formation of Fe-P or Fe-Al complexes. Addition of S, however, decreased the plants N:P ratio, indicating an effect of S on the N:P stoichiometry and an effect on the plant's P-demand. Phosphatase activity increased significantly after addition of S, but was not affected by the addition of N or a single drought event. Root phosphatase activity was also positively related to plant tissue N and P concentrations, plant N and P uptake, and plant aboveground biomass, suggesting that the phosphatase enzyme influences P-biogeochemistry. Our results demonstrated that it is difficult to predict the effects of wetland restoration, since the involved mechanisms are not fully understood. Short-term and long-term effects on root phosphatase activity may differ considerably. Additionally, the addition of S can lead to unexpected effects on the biogeochemistry of P. Our results showed that natural resource managers should be careful when restoring degraded fens or preventing desiccation of fen ecosystems. PMID:19101022

  15. Grief and attitudes toward suicide in peers affected by a cluster of suicides as adolescents.

    PubMed

    Abbott, Caroline H; Zakriski, Audrey L

    2014-12-01

    Eighty-five young adults exposed to a cluster of peer suicides as adolescents completed measures of attitudes toward suicide, grief, and social support. Closeness to the peers lost to suicide was positively correlated with grief and the belief that suicide is not preventable, with grief further elevated in close individuals with high social support from friends. Overall, social support was related to healthy attitudes about suicide including preventability, yet it was also related to some stigmatizing beliefs. Compared with 67 young adults who had not been exposed to a suicide cluster, the exposed sample was more likely to think that suicide is normal but more likely to think of it as incomprehensible. PMID:24806293

  16. Seizure Clustering during Drug Treatment Affects Seizure Outcome and Mortality of Childhood-Onset Epilepsy

    ERIC Educational Resources Information Center

    Sillanpaa, Matti; Schmidt, Dieter

    2008-01-01

    To provide evidence of whether seizure clustering is associated with drug resistance and increased mortality in childhood-onset epilepsy, a prospective, long-term population-based study was performed. One hundred and twenty patients who had been followed since disease onset (average age 37.0 years, SD 7.1, median 40.0, range 11-42; incident cases)…

  17. 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]. PMID:27317970

  18. Continuous nitrogen application differentially affects growth, yield,and nitrogen use efficiency of Leymus chinensis in two saline–sodic soils of Northeastern China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leymus chinensis (Trin.) Tzvel. (Poaceae) is a dominant plant in the Western Songnen plain of Northeastern China, Soil salinization and alkalization, nitrogen deficiency and current management practices have resulted in grassland degradation in the region. The objective of this study was to investig...

  19. 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...

  20. Corn silage hybrid type and quality of alfalfa hay affect dietary nitrogen utilization by early lactating dairy cows.

    PubMed

    Holt, M S; Neal, K; Eun, J-S; Young, A J; Hall, J O; Nestor, K E

    2013-10-01

    This experiment was conducted to determine the effects of corn silage (CS) hybrids and quality of alfalfa hay (AH) in high-forage dairy diets on N utilization, ruminal fermentation, and lactational performance by early-lactating dairy cows. Eight multiparous Holstein cows were used in a duplicated 4 × 4 Latin square experiment with a 2 × 2 factorial arrangement of dietary treatments. The 8 cows (average days in milk = 23 ± 11.2) were surgically fitted with ruminal cannula, and the 2 squares were conducted simultaneously. Within square, cows were randomly assigned to a sequence of 4 diets: conventional CS (CCS) or brown midrib CS (BMR) was combined with fair-quality AH [FAH: 46.7% neutral detergent fiber (NDF) and 18.4% crude protein (CP)] or high-quality AH (HAH: 39.2% NDF and 20.7% CP) to form 4 treatments: CCS with FAH, CCS with HAH, BMR with FAH, and BMR with HAH. Diets were isonitrogenous across treatments, averaging 15.9% CP. Each period lasted a total of 21 d, with 14 d for treatment adaptation and 7d for data collection and sampling. Intake of DM and milk yield did not differ in response to CS hybrids or AH quality. Although feeding BMR-based diets decreased urinary N output by 24%, it did not affect fecal N output. Feeding HAH decreased urinary N output by 15% but increased fecal N output by 20%. Nitrogen efficiency [milk N (g/d)/intake N (g/d)] tended to increase for BMR treatments. Ruminal ammonia-N concentration was lower for cows fed BMR-based diets than for those fed CCS-based diets but was not affected by quality of AH. Feeding BMR-based diets or HAH decreased milk urea N concentration by 23 or 15%, respectively, compared with CCS-based diets or FAH. Total volatile fatty acid concentration increased with HAH but was not influenced by CS hybrids. Feeding BMR-based diets decreased urinary N-to-fecal N ratio (UN:FN), and it was further reduced by feeding HAH. Although cows fed the BMR-based diets tended to increase milk N-to-manure N ratio, the

  1. 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

  2. How the extinction of extragalactic background light affects surface photometry of galaxies, groups and clusters

    NASA Astrophysics Data System (ADS)

    Zackrisson, E.; Micheva, G.; Östlin, G.

    2009-08-01

    The faint regions of galaxies, groups and clusters hold important clues about how these objects formed, and surface photometry at optical and near-infrared wavelengths represents a powerful tool for studying such structures. Here, we identify a hitherto unrecognized problem with this technique, related to how the night sky flux is typically measured and subtracted from astronomical images. While most of the sky flux comes from regions between the observer and the target object, a small fraction - the extragalactic background light (EBL) - comes from behind. We argue that since this part of the sky flux can be subjected to extinction by dust present in the galaxy/group/cluster studied, standard reduction procedures may lead to a systematic oversubtraction of the EBL. Even very small amounts of extinction can lead to spurious features in radial surface brightness profiles and colour maps of extended objects. We assess the likely impact of this effect on a number of topics in extragalactic astronomy where very deep surface photometry is currently attempted, including studies of stellar haloes, starburst host galaxies, disc truncations and diffuse intragroup/intracluster light. We argue that EBL extinction may provide at least a partial explanation for the anomalously red colours reported for the haloes of disc galaxies and for the hosts of local starburst galaxies. EBL extinction effects also mimic truncations in discs with unusually high dust opacities, but are unlikely to be the cause of such features in general. Failure to account for EBL extinction can also give rise to a non-negligible underestimate of intragroup and intracluster light at the faintest surface brightness levels currently probed. Finally, we discuss how EBL extinction effects may be exploited to provide an independent constraint on the surface brightness of the EBL, using a combination of surface photometry and direct star counts.

  3. Power training and postmenopausal hormone therapy affect transcriptional control of specific co-regulated gene clusters in skeletal muscle

    PubMed Central

    Fey, Vidal; Törmäkangas, Timo; Ronkainen, Paula H. A.; Taaffe, Dennis R.; Takala, Timo; Koskinen, Satu; Cheng, Sulin; Puolakka, Jukka; Kujala, Urho M.; Suominen, Harri; Sipilä, Sarianna; Kovanen, Vuokko

    2010-01-01

    At the moment, there is no clear molecular explanation for the steeper decline in muscle performance after menopause or the mechanisms of counteractive treatments. The goal of this genome-wide study was to identify the genes and gene clusters through which power training (PT) comprising jumping activities or estrogen containing hormone replacement therapy (HRT) may affect skeletal muscle properties after menopause. We used musculus vastus lateralis samples from early stage postmenopausal (50–57 years old) women participating in a yearlong randomized double-blind placebo-controlled trial with PT and HRT interventions. Using microarray platform with over 24,000 probes, we identified 665 differentially expressed genes. The hierarchical clustering method was used to assort the genes. Additionally, enrichment analysis of gene ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways was carried out to clarify whether assorted gene clusters are enriched with particular functional categories. The analysis revealed transcriptional regulation of 49 GO/KEGG categories. PT upregulated transcription in “response to contraction”—category revealing novel candidate genes for contraction-related regulation of muscle function while HRT upregulated gene expression related to functionality of mitochondria. Moreover, several functional categories tightly related to muscle energy metabolism, development, and function were affected regardless of the treatment. Our results emphasize that during the early stages of the postmenopause, muscle properties are under transcriptional modulation, which both PT and HRT partially counteract leading to preservation of muscle power and potentially reducing the risk for aging-related muscle weakness. More specifically, PT and HRT may function through improving energy metabolism, response to contraction as well as by preserving functionality of the mitochondria. Electronic supplementary material The online version of this

  4. Stratification and Storage of Soil Organic Carbon and Nitrogen as Affected by Tillage Practices in the North China Plain

    PubMed Central

    Zhang, Xiang-Qian; Kong, Fan-Lei; Chen, Fu; Lal, Rattan; Zhang, Hai-Lin

    2015-01-01

    Tillage practices can redistribute the soil profiles, and thus affects soil organic carbon (SOC), and its storage. The stratification ratio (SR) can be an indicator of soil quality. This study was conducted to determine tillage effects on the profile distribution of certain soil properties in winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) systems in the North China Plain (NCP). Three tillage treatments, including no till (NT), rotary tillage (RT), and plow tillage (PT), were established in 2001 in Luancheng County, Hebei Province. The concentration, storage, and SR of SOC and soil total nitrogen (TN) were assessed in both the wheat and maize seasons. Compared with RT and PT, the mean SRs for all depth ratios of SOC under NT increased by 7.85% and 30.61% during the maize season, and by 14.67% and 30.91% during the wheat season, respectively. The SR of TN for 0–5:30–50 cm increased by 140%, 161%, and 161% in the maize season, and 266%, 154%, and 122% in the wheat season compared to the SR for 0–5:5–10 cm under NT, RT and PT, respectively. The data indicated that SOC and TN were both concentrated in the surface-soil layers (0–10 cm) under NT but were distributed relatively evenly through the soil profile under PT. Meanwhile, the storage of SOC and TN was higher under NT for the surface soil (0–10 cm) but was higher under PT for the deeper soil (30–50 cm). Furthermore, the storage of SOC and TN was significantly related to SR of SOC and TN along the whole soil profile (P<0.0001). Therefore, SR could be used to explain and indicate the changes in the storage of SOC and TN. Further, NT stratifies SOC and TN, enhances the topsoil SOC storage, and helps to improve SOC sequestration and soil quality. PMID:26075391

  5. Long-term nitrogen additions increase likelihood of climate stress and affect recovery from wildfire in a lowland heath.

    PubMed

    Southon, Georgina E; Green, Emma R; Jones, Alan G; Barker, Chris G; Power, Sally A

    2012-09-01

    Increases in the emissions and associated atmospheric deposition of nitrogen (N) have the potential to cause significant changes to the structure and function of N-limited ecosystems. Here, we present the results of a long-term (13 year) experiment assessing the impacts of N addition (30 kg ha(-1)  yr(-1) ) on a UK lowland heathland under a wide range of environmental conditions, including the occurrence of prolonged natural drought episodes and a severe summer fire. Our findings indicate that elevated N deposition results in large, persistent effects on Calluna growth, phenology and chemistry, severe suppression of understorey lichen flora and changes in soil biogeochemistry. Growing season rainfall was found to be a strong driver of inter-annual variation in Calluna growth and, although interactions between N and rainfall for shoot growth were not significant until the later phase of the experiment, N addition exacerbated the extent of drought injury to Calluna shoots following naturally occurring droughts in 2003 and 2009. Following a severe wildfire at the experimental site in 2006, heathland regeneration dynamics were significantly affected by N, with a greater abundance of pioneering moss species and suppression of the lichen flora in plots receiving N additions. Significant interactions between climate and N were also apparent post fire, with the characteristic stimulation in Calluna growth in +N plots suppressed during dry years. Carbon (C) and N budgets demonstrate large increases in both above- and below-ground stocks of these elements in N-treated plots prior to the fire, despite higher levels of soil microbial activity and organic matter turnover. Although much of the organic material was removed during the fire, pre-existing treatment differences were still evident following the burn. Post fire accumulation of below-ground C and N stocks was increased rapidly in N-treated plots, highlighting the role of N deposition in ecosystem C sequestration

  6. Does training frequency and supervision affect compliance, performance and muscular health? A cluster randomized controlled trial.

    PubMed

    Dalager, Tina; Bredahl, Thomas G V; Pedersen, Mogens T; Boyle, Eleanor; Andersen, Lars L; Sjøgaard, Gisela

    2015-10-01

    The aim was to determine the effect of one weekly hour of specific strength training within working hours, performed with the same total training volume but with different training frequencies and durations, or with different levels of supervision, on compliance, muscle health and performance, behavior and work performance. In total, 573 office workers were cluster-randomized to: 1 WS: one 60-min supervised session/week, 3 WS: three 20-min supervised sessions/week, 9 WS: nine 7-min supervised sessions/week, 3 MS: three 20-min sessions/week with minimal supervision, or REF: a reference group without training. Outcomes were diary-based compliance, total training volume, muscle performance and questionnaire-based health, behavior and work performance. Comparisons were made among the WS training groups and between 3 WS and 3 MS. If no difference, training groups were collapsed (TG) and compared with REF. Results demonstrated similar degrees of compliance, mean(range) of 39(33-44)%, and total training volume, 13.266(11.977-15.096)kg. Musculoskeletal pain in neck and shoulders were reduced with approx. 50% in TG, which was significant compared with REF. Only the training groups improved significantly their muscle strength 8(4-13)% and endurance 27(12-37)%, both being significant compared with REF. No change in workability, productivity or self-rated health was demonstrated. Secondary analysis showed exercise self-efficacy to be a significant predictor of compliance. Regardless of training schedule and supervision, similar degrees of compliance were shown together with reduced musculoskeletal pain and improved muscle performance. These findings provide evidence that a great degree of flexibility is legitimate for companies in planning future implementation of physical exercise programs at the workplace. ClinicalTrials.gov, number NCT01027390. PMID:25816746

  7. The Genetics of Symbiotic Nitrogen Fixation: Comparative Genomics of 14 Rhizobia Strains by Resolution of Protein Clusters

    PubMed Central

    Black, Michael; Moolhuijzen, Paula; Chapman, Brett; Barrero, Roberto; Howieson, John; Hungria, Mariangela; Bellgard, Matthew

    2012-01-01

    The symbiotic relationship between legumes and nitrogen fixing bacteria is critical for agriculture, as it may have profound impacts on lowering costs for farmers, on land sustainability, on soil quality, and on mitigation of greenhouse gas emissions. However, despite the importance of the symbioses to the global nitrogen cycling balance, very few rhizobial genomes have been sequenced so far, although there are some ongoing efforts in sequencing elite strains. In this study, the genomes of fourteen selected strains of the order Rhizobiales, all previously fully sequenced and annotated, were compared to assess differences between the strains and to investigate the feasibility of defining a core ‘symbiome’—the essential genes required by all rhizobia for nodulation and nitrogen fixation. Comparison of these whole genomes has revealed valuable information, such as several events of lateral gene transfer, particularly in the symbiotic plasmids and genomic islands that have contributed to a better understanding of the evolution of contrasting symbioses. Unique genes were also identified, as well as omissions of symbiotic genes that were expected to be found. Protein comparisons have also allowed the identification of a variety of similarities and differences in several groups of genes, including those involved in nodulation, nitrogen fixation, production of exopolysaccharides, Type I to Type VI secretion systems, among others, and identifying some key genes that could be related to host specificity and/or a better saprophytic ability. However, while several significant differences in the type and number of proteins were observed, the evidence presented suggests no simple core symbiome exists. A more abstract systems biology concept of nitrogen fixing symbiosis may be required. The results have also highlighted that comparative genomics represents a valuable tool for capturing specificities and generalities of each genome. PMID:24704847

  8. Winter Cover Crop Seeding Rate and Variety Affects during 8 Years of Organic Vegetables 2. Cover Crop Nitrogen Accumulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Winter cover crops (CC) can improve nutrient-use efficiency in vegetable systems. Nitrogen uptake (NU), and shoot residue quality of rye (Secale cereale L.), legume-rye, and mustard was determined in December, January, and February or March during the first 8 yr of the Salinas Organic Cropping Syst...

  9. Yeast genes involved in sulfur and nitrogen metabolism affect the production of volatile thiols from Sauvignon Blanc musts.

    PubMed

    Harsch, Michael J; Gardner, Richard C

    2013-01-01

    Two volatile thiols, 3-mercaptohexan-1-ol (3MH), and 3-mercaptohexyl-acetate (3MHA), reminiscent of grapefruit and passion fruit respectively, are critical varietal aroma compounds in Sauvignon Blanc (SB) wines. These aromatic thiols are not present in the grape juice but are synthesized and released by the yeast during alcoholic fermentation. Single deletion mutants of 67 candidate genes in a laboratory strain of Saccharomyces cerevisiae were screened using gas chromatography mass spectrometry for their thiol production after fermentation of SB grape juice. None of the deletions abolished production of the two volatile thiols. However, deletion of 17 genes caused increases or decreases in production by as much as twofold. These 17 genes, mostly related to sulfur and nitrogen metabolism in yeast, may act by altering the regulation of the pathway(s) of thiol production or altering substrate supply. Deleting subsets of these genes in a wine yeast strain gave similar results to the laboratory strain for sulfur pathway genes but showed strain differences for genes involved in nitrogen metabolism. The addition of two nitrogen sources, urea and di-ammonium phosphate, as well as two sulfur compounds, cysteine and S-ethyl-L-cysteine, increased 3MH and 3MHA concentrations in the final wines. Collectively these results suggest that sulfur and nitrogen metabolism are important in regulating the synthesis of 3MH and 3MHA during yeast fermentation of grape juice. PMID:22684328

  10. Effect of nitrogen as co-dopant in carbon and boron-doped ZnO clusters

    NASA Astrophysics Data System (ADS)

    Kapila, Neha; Sharma, Gaurav; Mudahar, Isha; Sharma, Hitesh

    2016-05-01

    The effect of N as co-dopant have been investigated on magnetic properties of C and B-doped (ZnO)n clusters (n = 1 - 16) using spin-polarized density functional theory. Total energy calculations show that C and N more stable when substituted at O site, whereas B is more stable at the Zn site. The B:N co-doping is energetically more stable than C:N which is more stable than N:N doping. C and N atoms do not show tendency to form clusters when doped separately. The magnetic moment (MM) of C-doped ZnO clusters is enhanced significantly with N co-doping. The MM of 2 μB, 1 μB and 1 μB per atom is induced due to C, N and B respectively. The MM of 3 μB or 5 μB and 2 μB or 4 μB are observed for co-doping of 2C:N and C:2N respectively. In contrary, the MM in 2B:N and B:2N co-doped (ZnO)n remains 1 μB for n=2-4, 12 and 16. The results are in agreement with the available theoretical results.

  11. 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

  12. Analysis of variables affecting unemployment rate and detecting for cluster in West Java, Central Java, and East Java in 2012

    NASA Astrophysics Data System (ADS)

    Samuel, Putra A.; Widyaningsih, Yekti; Lestari, Dian

    2016-02-01

    The objective of this study is modeling the Unemployment Rate (UR) in West Java, Central Java, and East Java, with rate of disease, infant mortality rate, educational level, population size, proportion of married people, and GDRP as the explanatory variables. Spatial factors are also considered in the modeling since the closer the distance, the higher the correlation. This study uses the secondary data from BPS (Badan Pusat Statistik). The data will be analyzed using Moran I test, to obtain the information about spatial dependence, and using Spatial Autoregressive modeling to obtain the information, which variables are significant affecting UR and how great the influence of the spatial factors. The result is, variables proportion of married people, rate of disease, and population size are related significantly to UR. In all three regions, the Hotspot of unemployed will also be detected districts/cities using Spatial Scan Statistics Method. The results are 22 districts/cities as a regional group with the highest unemployed (Most likely cluster) in the study area; 2 districts/cities as a regional group with the highest unemployed in West Java; 1 district/city as a regional groups with the highest unemployed in Central Java; 15 districts/cities as a regional group with the highest unemployed in East Java.

  13. Elevated CO(2) concentration affects leaf photosynthesis-nitrogen relationships in Pinus taeda over nine years in FACE.

    PubMed

    Crous, Kristine Y; Walters, Michael B; Ellsworth, David S

    2008-04-01

    To investigate whether long-term elevated carbon dioxide concentration ([CO(2)]) causes declines in photosynthetic enhancement and leaf nitrogen (N) owing to limited soil fertility, we measured photosynthesis, carboxylation capacity and area-based leaf nitrogen concentration (N(a)) in Pinus taeda L. growing in a long-term free-air CO(2) enrichment (FACE) facility at an N-limited site. We also determined how maximum rates of carboxylation (V(cmax)) and electron transport (J(max)) varied with N(a) under elevated [CO(2)]. In trees exposed to elevated [CO(2)] for 5 to 9 years, the slope of the relationship between leaf photosynthetic capacity (A(net-Ca)) and N(a) was significantly reduced by 37% in 1-year-old needles, whereas it was unaffected in current-year needles. The slope of the relationships of both V(cmax) and J(max) with N(a) decreased in 1-year-old needles after up to 9 years of growth in elevated [CO(2)], which was accompanied by a 15% reduction in N allocation to the carboxylating enzyme. Nitrogen fertilization (110 kg N ha(-1)) in the ninth year of exposure to elevated [CO(2)] restored the slopes of the relationships of V(cmax) and J(max) with N(a) to those of control trees (i.e., in ambient [CO(2)]). The J(max):V(cmax) ratio was unaffected by either [CO(2)] or N fertilization. Changes in the apparent allocation of N to photosynthetic components may be an important adjustment in pines exposed to elevated [CO(2)] on low-fertility sites. We conclude that fundamental relationships between photosynthesis or its component processes with N(a) may be altered in aging pine needles after more than 5 years of exposure to elevated atmospheric [CO(2)]. PMID:18244946

  14. Five-year changes in soil organic carbon and total nitrogen in coastal wetlands affected by flow-sediment regulation in a Chinese delta

    NASA Astrophysics Data System (ADS)

    Wang, Junjing; Bai, Junhong; Zhao, Qingqing; Lu, Qiongqiong; Xia, Zhijian

    2016-02-01

    Changes in the sources and sinks of soil organic carbon (SOC) and total nitrogen (TN) in wetland soils as indicators of soil quality and climate change have received attention worldwide. Soil samples were collected in 2007 and 2012 in the coastal wetlands of the Yellow River Delta and the SOC and TN were determined to investigate a five-year change in their content and stock in these wetlands as affected by flow-sediment regulation. Our results revealed that the soils in 2007 exhibited greater electrical conductivities, SOC content and density, and ammonium nitrogen (NH4+-N) levels in the top 10 cm soils (p < 0.05) compared with the soils in 2012. In general, the SOC and TN contents decreased with increasing soil depth. However, the highest ratios of soil organic carbon and total nitrogen (molar C/N ratios) were observed in the 30-40 cm soil layer. A significant SOC loss occurred (p < 0.05) in top 10 cm soils, but only a small change in SOC in the top 50 cm soils. Comparatively, TN levels did not show significant differences in the study period.

  15. Five-year changes in soil organic carbon and total nitrogen in coastal wetlands affected by flow-sediment regulation in a Chinese delta.

    PubMed

    Wang, Junjing; Bai, Junhong; Zhao, Qingqing; Lu, Qiongqiong; Xia, Zhijian

    2016-01-01

    Changes in the sources and sinks of soil organic carbon (SOC) and total nitrogen (TN) in wetland soils as indicators of soil quality and climate change have received attention worldwide. Soil samples were collected in 2007 and 2012 in the coastal wetlands of the Yellow River Delta and the SOC and TN were determined to investigate a five-year change in their content and stock in these wetlands as affected by flow-sediment regulation. Our results revealed that the soils in 2007 exhibited greater electrical conductivities, SOC content and density, and ammonium nitrogen (NH4(+)-N) levels in the top 10 cm soils (p < 0.05) compared with the soils in 2012. In general, the SOC and TN contents decreased with increasing soil depth. However, the highest ratios of soil organic carbon and total nitrogen (molar C/N ratios) were observed in the 30-40 cm soil layer. A significant SOC loss occurred (p < 0.05) in top 10 cm soils, but only a small change in SOC in the top 50 cm soils. Comparatively, TN levels did not show significant differences in the study period. PMID:26879008

  16. Five-year changes in soil organic carbon and total nitrogen in coastal wetlands affected by flow-sediment regulation in a Chinese delta

    PubMed Central

    Wang, Junjing; Bai, Junhong; Zhao, Qingqing; Lu, Qiongqiong; Xia, Zhijian

    2016-01-01

    Changes in the sources and sinks of soil organic carbon (SOC) and total nitrogen (TN) in wetland soils as indicators of soil quality and climate change have received attention worldwide. Soil samples were collected in 2007 and 2012 in the coastal wetlands of the Yellow River Delta and the SOC and TN were determined to investigate a five-year change in their content and stock in these wetlands as affected by flow-sediment regulation. Our results revealed that the soils in 2007 exhibited greater electrical conductivities, SOC content and density, and ammonium nitrogen (NH4+-N) levels in the top 10 cm soils (p < 0.05) compared with the soils in 2012. In general, the SOC and TN contents decreased with increasing soil depth. However, the highest ratios of soil organic carbon and total nitrogen (molar C/N ratios) were observed in the 30–40 cm soil layer. A significant SOC loss occurred (p < 0.05) in top 10 cm soils, but only a small change in SOC in the top 50 cm soils. Comparatively, TN levels did not show significant differences in the study period. PMID:26879008

  17. Measuring human rights violations in a conflict-affected country: results from a nationwide cluster survey in Central African Republic

    PubMed Central

    2011-01-01

    Background Measuring human rights violations is particularly challenging during or after armed conflict. A recent nationwide survey in the Central African Republic produced estimates of rates of grave violations against children and adults affected by armed conflict, using an approach known as the "Neighborhood Method". Methods In June and July, 2009, a random household survey was conducted based on population estimates from the 2003 national census. Clusters were assigned systematically proportional to population size. Respondents in randomly selected households were interviewed regarding incidents of killing, intentional injury, recruitment into armed groups, abduction, sexual abuse and rape between January 1, 2008 and the date of interview, occurring in their homes' and those of their three closest neighbors. Results Sixty of the selected 69 clusters were surveyed. In total, 599 women were interviewed about events in 2,370 households representing 13,669 persons. Estimates of annual rates of each violation occurring per 1000 people in each of two strata are provided for children between the ages of five and 17, adults 18 years of age and older and the entire population five years and older, along with a combined and weighted national rate. The national rates for children age five to 17 were estimated to be 0.98/1000/year (95% CI: 0.18 - 1.78) for recruitment, 2.56/1000/year (95% CI: 1.50 - 3.62) for abduction, 1.13/1000/year (95% CI: 0.33 - 1.93) for intentional injury, 10.72/1000 girls/year (95% CI: 7.40 - 14.04) for rape, and 4.80/1000 girls/year (95% CI: 2.61 - 6.00) for sexual abuse. No reports of any violation against a person under the age of five were recorded and there were no reports of rape or sexual abuse of males. No children were reported to have been killed during the recall period. Rape and abduction were the most frequently reported events. Conclusions The population-based figures greatly augment existing information on human rights violations in

  18. Metabolic profiles of Lolium perenne are differentially affected by nitrogen supply, carbohydrate content, and fungal endophyte infection.

    PubMed

    Rasmussen, Susanne; Parsons, Anthony J; Fraser, Karl; Xue, Hong; Newman, Jonathan A

    2008-03-01

    Lolium perenne cultivars differing in their capacity to accumulate water soluble carbohydrates (WSCs) were infected with three strains of fungal Neotyphodium lolii endophytes or left uninfected. The endophyte strains differed in their alkaloid profiles. Plants were grown at two different levels of nitrogen (N) supply in a controlled environment. Metabolic profiles of blades were analyzed using a variety of analytical methods. A total of 66 response variables were subjected to a principle components analysis and factor rotation. The first three rotated factors (46% of the total variance) were subsequently analyzed by analysis of variance. At high N supply nitrogenous compounds, organic acids and lipids were increased; WSCs, chlorogenic acid (CGA), and fibers were decreased. The high-sugar cultivar 'AberDove' had reduced levels of nitrate, most minor amino acids, sulfur, and fibers compared to the control cultivar 'Fennema', whereas WSCs, CGA, and methionine were increased. In plants infected with endophytes, nitrate, several amino acids, and, magnesium were decreased; WSCs, lipids, some organic acids, and CGA were increased. Regrowth of blades was stimulated at high N, and there was a significant endophyte x cultivar interaction on regrowth. Mannitol, a fungal specific sugar alcohol, was significantly correlated with fungal biomass. Our findings suggest that effects of endophytes on metabolic profiles of L. perenne can be considerable, depending on host plant characteristics and nutrient supply, and we propose that a shift in carbon/N ratios and in secondary metabolite production as seen in our study is likely to have impacts on herbivore responses. PMID:18218971

  19. Change in Uptake, Transport and Accumulation of Ions in Nerium oleander (Rosebay) as Affected by Different Nitrogen Sources and Salinity

    PubMed Central

    Abdolzadeh, Ahmad; Shima, Kazuto; Lambers, Hans; Chiba, Kyozo

    2008-01-01

    Background and Aims The source of nitrogen plays an important role in salt tolerance of plants. In this study, the effects of NaCl on net uptake, accumulation and transport of ions were investigated in Nerium oleander with ammonium or nitrate as the nitrogen source in order to analyse differences in uptake and cycling of ions within plants. Methods Plants were grown in a greenhouse in hydroponics under different salt treatments (control vs. 100 mm NaCl) with ammonium or nitrate as the nitrogen source, and changes in ion concentration in plants, xylem sap exuded from roots and stems, and phloem sap were determined. Key Results Plant weight, leaf area and photosynthetic rate showed a higher salt tolerance of nitrate-fed plants compared with that of ammonium-fed plants. The total amount of Na+ transported in the xylem in roots, accumulated in the shoot and retranslocated in the phloem of ammonium-fed plants under salt treatment was 1·8, 1·9 and 2·7 times more, respectively, than that of nitrate-treated plants. However, the amount of Na+ accumulated in roots in nitrate-fed plants was about 1·5 times higher than that in ammonium-fed plants. Similarly, Cl− transport via the xylem to the shoot and its retranslocation via the phloem (Cl− cycling) were far greater with ammonium treatment than with nitrate treatment under conditions of salinity. The uptake and accumulation of K+ in shoots decreased more due to salinity in ammonium-fed plants compared with nitrate-fed plants. In contrast, K+ cycling in shoots increased due to salinity, with higher rates in the ammonium-treated plants. Conclusions The faster growth of nitrate-fed plants under conditions of salinity was associated with a lower transport and accumulation of Na+ and Cl− in the shoot, whereas in ammonium-fed plants accumulation and cycling of Na+ and Cl− in shoots probably caused harmful effects and reduced growth of plants. PMID:18772147

  20. Structure-function relationships affecting the sensing mechanism of monolayer-protected cluster doped xerogel amperometric glucose biosensors.

    PubMed

    DiPasquale, Luke T; Poulos, Nicholas G; Hall, Jackson R; Minocha, Aastha; Bui, Tram Anh; Leopold, Michael C

    2015-07-15

    A systematic study of the structure-function relationships critical to understanding the sensing mechanism of 1st generation amperometric glucose biosensors with an embedded nanoparticle (NP) network is presented. Xerogel-based films featuring embedded glucose oxidase enzyme and doped with alkanethiolate-protected gold NPs, known as monolayer protected clusters (MPCs), exhibit significantly enhanced performance compared to analogous systems without NPs including higher sensitivity, faster response time, and extended linear/dynamic ranges. The proposed mechanism involves diffusion of the glucose to glucose oxidase within the xerogel, enzymatic reaction production of H2O2 with subsequent diffusion to the embedded network of MPCs where it is oxidized, an event immediately reported via fast electron transfer (ET) through the MPC system to the working electrode. Various aspects of the film construct and strategy are systematically probed using amperometry, voltammetry, and solid-state electronic conductivity measurements, including the effects of MPC peripheral chain length, MPC functionalization via place-exchange reaction, MPC core size, and the MPC density or concentration within the xerogel composite films. The collective results of these experiments support the proposed mechanism and identify interparticle spacing and the electronic communication through the MPC network is the most significant factor in the sensing scheme with the diffusional aspects of the mechanism that may be affected by film/MPC hydrophobicity and functionality (i.e., glucose and H2O2 diffusion) shown to be less substantial contributors to the overall enhanced performance. Understanding the structure-function relationships of effective sensing schemes allows for the employment of the strategy for future biosensor design toward clinically relevant targets. PMID:25819004

  1. Six-year growth of Eucalyptus saligna plantings as affected by nitrogen and phosphorus fertilizer. Forest Service research paper (Final)

    SciTech Connect

    Whitesell, C.D.; DeBell, D.S.; Schubert, T.H.

    1987-10-01

    Growth responses of Eucalyptus saligna to nitrogen (N) and phosphorus (P) fertilizers were assessed in bioenergy plantations on abandoned sugarcane land in Hawaii. Fertilizers were applied three times (0.6, and 15 months after planting) in a factorial design with four dosages each of N(0, 25, 50, and 75 g urea per tree) and P(0, 30, 60, and 90 g triple superphosphate per tree). Phosphorus and the N x P interaction had little effect on tree growth. Effects of N, however, were dramatic during the first year, and benefits were sustained through 6 years. Effects of N on height growth and diameter growth dropped markedly during the third year and thereafter. Bioenergy plantations of E. saligna established on similar sites and soils will benefit from high dosages of N fertilizer and presumably from repeated applications.

  2. School-based mental health intervention for children in war-affected Burundi: a cluster randomized trial

    PubMed Central

    2014-01-01

    Background Armed conflicts are associated with a wide range of impacts on the mental health of children and adolescents. We evaluated the effectiveness of a school-based intervention aimed at reducing symptoms of posttraumatic stress disorder, depression, and anxiety (treatment aim); and improving a sense of hope and functioning (preventive aim). Methods We conducted a cluster randomized trial with 329 children in war-affected Burundi (aged 8 to 17 (mean 12.29 years, standard deviation 1.61); 48% girls). One group of children (n = 153) participated in a 15-session school-based intervention implemented by para-professionals, and the remaining 176 children formed a waitlist control condition. Outcomes were measured before, one week after, and three months after the intervention. Results No main effects of the intervention were identified. However, longitudinal growth curve analyses showed six favorable and two unfavorable differences in trajectories between study conditions in interaction with several moderators. Children in the intervention condition living in larger households showed decreases on depressive symptoms and function impairment, and those living with both parents showed decreases on posttraumatic stress disorder and depressive symptoms. The groups of children in the waitlist condition showed increases in depressive symptoms. In addition, younger children and those with low levels of exposure to traumatic events in the intervention condition showed improvements on hope. Children in the waitlist condition who lived on their original or newly bought land showed improvements in hope and function impairment, whereas children in the intervention condition showed deterioration on these outcomes. Conclusions Given inconsistent effects across studies, findings do not support this school-based intervention as a treatment for posttraumatic stress disorder and depressive symptoms in conflict-affected children. The intervention appears to have more consistent

  3. Nitrous oxide emissions from rape field as affected by nitrogen fertilizer management: A case study in Central China

    NASA Astrophysics Data System (ADS)

    Lin, Shan; Iqbal, Javed; Hu, Ronggui; Wu, Jinshui; Zhao, Jinsong; Ruan, Leilei; Malghani, Saadatullah

    2011-03-01

    Agricultural soils are one of the major sources of atmospheric nitrous oxide (N 2O) emission. Red soil, one of the typical agricultural soils in sub-tropical China, plays an important role in the global N 2O flux emissions. To determine its N mineralization potential, a field study was conducted to assess the effect of application of nitrogen (N) fertilizer in a rape field under red soil at the experimental station of Heshengqiao at Xianning, Hubei, China. To estimate N-induced N 2O flux, we examined N 2O flux during the growth stages of the rape field including four treatments: fertilizer PK (N0), fertilizer NPK (60 kg N ha -1) (N1), fertilizer NPK (120 kg N ha -1) (N2), fertilizer NPK (240 kg N ha -1) (N3). There were distinct variations in soil N 2O fluxes (from 0.16 to 0.90 kg N ha -1), with higher values being observed during the spring and autumn while low values were observed during winter season. Among different treatments, N fertilization significantly increased the N 2O fluxes, with highest fluxes from N3 while lowest values being observed from N0 treatment. This suggested increased microbial activity in response to increased N fertilizer application. It was interesting to note that fertilizer-induced emissions decreased as the applied fertilizer amount was increased. During the whole growing season, N 2O flux did not correlate with soil temperature, but it significantly correlated to other environmental variables; water-filled pore space (WFPS), soil NO 3--N and NH 4+-N contents, which suggests the need for efficient water use and low inorganic nitrogen fertilizer management practices.

  4. Nitrogen and Phosphorus Loads in an Agricultural Watershed Affected by Poultry Litter Application and Wastewater Effluent, Northeastern Oklahoma and Northwestern Arkansas, 2002-2009

    NASA Astrophysics Data System (ADS)

    Esralew, R.; Tortorelli, R. L.

    2010-12-01

    The Eucha-Spavinaw Basin in Northeastern Oklahoma and Northwestern Arkansas is the source of water for Lake Eucha and Spavinaw Lake, which are part of the water supply for the city of Tulsa, Oklahoma. Lake Eucha and Spavinaw Lakes have experienced deteriorating water quality largely due to growth of algae, notably cyanobacteria, from the excess input of nutrients. As a result, the city of Tulsa has spent millions of dollars to eliminate taste and odor problems resulting from production of algal and bacterial byproducts. To evaluate changes in nutrient loading resulting from a reduction in land application of poultry litter, installation of best management practices, and reductions in the phosphorus concentrations in wastewater effluent, the U.S. Geological Survey investigated nitrogen and phosphorus concentrations from samples collected during baseflow and runoff and used regression models to estimate nitrogen and phosphorus loads, yields, and flow-weighted concentrations in two major tributaries to Lake Eucha, Spavinaw and Beaty Creeks, for the period 2002-2009. Estimated mean flow-weighted total unfiltered nitrogen and phosphorus concentrations in the basin were about 5 to 10 times greater than the 75th percentile of flow-weighted nutrient concentrations in other mostly undeveloped basins of the United States. Spavinaw and Beaty Creeks contributed an estimated mean annual total load of about 762,500 kilograms of nitrogen and 49,200 kilograms of phosphorus per year, 76 to 91 percent of which was transported to Lake Eucha by runoff. Thirty-four percent of the nitrogen load and 48 percent of the phosphorus load to Lake Eucha occurred during the year 2008 which was the wettest year on record for the Eucha-Spavinaw Basin. The results of this analysis indicate that although efforts were made to control nutrient loading, nutrient concentrations, especially phosphorus, were substantially augmented by non-point sources and that most loading occurs during runoff events

  5. Root-zone acidity and nitrogen source affects Typha latifolia L. growth and uptake kinetics of ammonium and nitrate.

    PubMed

    Brix, Hans; Dyhr-Jensen, Kirsten; Lorenzen, Bent

    2002-12-01

    The NH(4)(+) and NO(3)(-) uptake kinetics by Typha latifolia L. were studied after prolonged hydroponics growth at constant pH 3.5, 5.0, 6.5 or 7.0 and with NH(4)(+) or NO(3)(-) as the sole N-source. In addition, the effects of pH and N source on H(+) extrusion and adenine nucleotide content were examined. Typha latifolia was able to grow with both N sources at near neutral pH levels, but the plants had higher relative growth rates, higher tissue concentrations of the major nutrients, higher contents of adenine nucleotides, and higher affinity for uptake of inorganic nitrogen when grown on NH(4)(+). Growth almost completely stopped at pH 3.5, irrespective of N source, probably as a consequence of pH effects on plasma membrane integrity and H(+) influx into the root cells. Tissue concentrations of the major nutrients and adenine nucleotides were severely reduced at low pH, and the uptake capacity for inorganic nitrogen was low, and more so for NO(3)(-)-fed than for NH(4)(+)-fed plants. The maximum uptake rate, V(max), was highest for NH(4)(+) at pH 6.5 (30.9 micro mol h(-1) g(-1) root dry weight) and for NO(3)(-) at pH 5.0 (31.7 micro mol h(-1) g(-1) root dry weight), and less than 10% of these values at pH 3.5. The affinity for uptake as estimated by the half saturation constant, K((1/2)), was lowest at low pH for NH(4)(+) and at high pH for NO(3)(-). The changes in V(max) and K((1/2)) were thus consistent with the theory of increasing competition between cations and H(+) at low pH and between anions and OH(-) at high pH. C(min) was independent of pH, but slightly higher for NO(3)(-) than for NH(4)(+) (C(min)(NH(4)(+)) approximately 0.8 mmol m(-3); C(min)(NO(3)(-)) approximately 2.8 mmol m(-3)). The growth inhibition at low pH was probably due to a reduced nutrient uptake and a consequential limitation of growth by nutrient stress. Typha latifolia seems to be well adapted to growth in wetland soils where NH(4)(+) is the prevailing nitrogen compound, but very low p

  6. Inclusion of sainfoin (Onobrychis viciifolia) silage in dairy cow rations affects nutrient digestibility, nitrogen utilization, energy balance, and methane emissions.

    PubMed

    Huyen, N T; Desrues, O; Alferink, S J J; Zandstra, T; Verstegen, M W A; Hendriks, W H; Pellikaan, W F

    2016-05-01

    Sainfoin (Onobrychis viciifolia) is a tanniniferous legume forage that has potential nutritional and health benefits preventing bloating, reducing nematode larval establishment, improving N utilization, and reducing greenhouse gas emissions. However, the use of sainfoin as a fodder crop in dairy cow rations in northwestern Europe is still relatively unknown. The objective of this study was to evaluate the effect of sainfoin silage on nutrient digestibility, animal performance, energy and N utilization, and CH4 production. Six rumen-cannulated, lactating dairy cows with a metabolic body weight (BW(0.75)) of 132.5±3.6kg were randomly assigned to either a control (CON) or a sainfoin (SAIN)-based diet over 2 experimental periods of 25 d each in a crossover design. The CON diet was a mixture of grass silage, corn silage, concentrate, and linseed. In the SAIN diet, 50% of grass silage dry matter (DM) of the CON diet was exchanged for sainfoin silage. The cows were adapted to 95% of ad libitum feed intake for a 21-d period before being housed in climate-controlled respiration chambers for 4 d, during which time feed intake, apparent total-tract digestibility, N and energy balance, and CH4 production was determined. Data were analyzed using a mixed model procedure. Total daily DM, organic matter, and neutral detergent fiber intake did not differ between the 2 diets. The apparent digestibility of DM, organic matter, neutral detergent fiber, and acid detergent fiber were, respectively, 5.7, 4.0, 15.7, and 14.8% lower for the SAIN diet. Methane production per kilogram of DM intake was lowest for the SAIN diet, CH4 production as a percentage of gross energy intake tended to be lower, and milk yield was greater for the SAIN diet. Nitrogen intake, N retention, and energy retained in body protein were greater for the SAIN than for the CON diet. Nitrogen retention as a percentage of N intake tended to be greater for the SAIN diet. These results suggest that inclusion of sainfoin

  7. Corrosion behavior in high heat input welded heat-affected zone of Ni-free high-nitrogen Fe–18Cr–10Mn–N austenitic stainless steel

    SciTech Connect

    Moon, Joonoh Ha, Heon-Young; Lee, Tae-Ho

    2013-08-15

    The pitting corrosion and interphase corrosion behaviors in high heat input welded heat-affected zone (HAZ) of a metastable high-nitrogen Fe–18Cr–10Mn–N austenitic stainless steel were explored through electrochemical tests. The HAZs were simulated using Gleeble simulator with high heat input welding condition of 300 kJ/cm and the peak temperature of the HAZs was changed from 1200 °C to 1350 °C, aiming to examine the effect of δ-ferrite formation on corrosion behavior. The electrochemical test results show that both pitting corrosion resistance and interphase corrosion resistance were seriously deteriorated by δ-ferrite formation in the HAZ and their aspects were different with increasing δ-ferrite fraction. The pitting corrosion resistance was decreased by the formation of Cr-depleted zone along δ-ferrite/austenite (γ) interphase resulting from δ-ferrite formation; however it didn't depend on δ-ferrite fraction. The interphase corrosion resistance depends on the total amount of Cr-depleted zone as well as ferrite area and thus continuously decreased with increasing δ-ferrite fraction. The different effects of δ-ferrite fraction on pitting corrosion and interphase corrosion were carefully discussed in terms of alloying elements partitioning in the HAZ based on thermodynamic consideration. - Highlights: • Corrosion behavior in the weld HAZ of high-nitrogen austenitic alloy was studied. • Cr{sub 2}N particle was not precipitated in high heat input welded HAZ of tested alloy. • Pitting corrosion and interphase corrosion show a different behavior. • Pitting corrosion resistance was affected by whether or not δ-ferrite forms. • Interphase corrosion resistance was affected by the total amount of δ-ferrite.

  8. Phosphorus availability and elevated CO2 affect biological nitrogen fixation and nutrient fluxes in a clover-dominated sward.

    PubMed

    Edwards, Everard J; McCaffery, Stephanie; Evans, John R

    2006-01-01

    The response of biological nitrogen fixation (BNF) to elevated CO(2) was examined in white clover (Trifolium repens)-dominated swards under both high and low phosphorus availability. Mixed swards of clover and buffalo grass (Stenotaphrum secundatum) were grown for 15 months in 0.2 m2 sand-filled mesocosms under two CO2 treatments (ambient and twice ambient) and three nutrient treatments [no N, and either low or high P (5 or 134 kg P ha(-1)); the third nutrient treatment was supplied with high P and N (240 kg N ha(-1))]. Under ambient CO2, high P increased BNF from 410 to 900 kg ha(-1). Elevated CO2 further increased BNF to 1180 kg ha(-1) with high P, but there was no effect of CO2 on BNF with low P. Allocation of N belowground increased by approx. 50% under elevated CO2 irrespective of supplied P. The results suggest that where soil P availability is low, elevated CO2 will not increase BNF, and pasture quality could decrease because of a reduction in aboveground N. PMID:16390427

  9. Partial shading of lateral branches affects growth, and foliage nitrogen- and water-use efficiencies in the conifer Cunninghamia lanceolata growing in a warm monsoon climate.

    PubMed

    Dong, Tingfa; Li, Junyu; Zhang, Yuanbin; Korpelainen, Helena; Niinemets, Ülo; Li, Chunyang

    2015-06-01

    The degree to which branches are autonomous in their acclimation responses to alteration in light environment is still poorly understood. We investigated the effects of shading of the sapling crown of Cunninghamia lanceolata (Lamb.) Hook on the whole-tree and mid-crown branch growth and current-year foliage structure and physiology. Four treatments providing 0, 50, 75 and 90% shading compared with full daylight (denoted as Treatment(0), Treatment(50%), Treatment(75%) and Treatment(90%), and Shaded(0), Shaded(50%), Shaded(75%) and Shaded(90%) for the shaded branches and Sunlit(0), Sunlit(50%), Sunlit(75%) and Sunlit(90%) for the opposite sunlit branches under natural light conditions, respectively), were applied over two consecutive growing seasons. Shading treatments decreased the growth of basal stem diameter, leaf dry mass per unit leaf area, stomatal conductance, transpiration rate, the ratio of water-soluble to structural leaf nitrogen content, photosynthetic nitrogen-use efficiency and instantaneous and long-term (estimated from carbon isotope composition) water-use efficiency in shaded branches. Differences between shaded and sunlit branches increased with increasing severity and duration of shading. A non-autonomous, partly compensatory behavior of non-shaded branches was observed for most traits, thus reflecting the dependence between the traits of sunlit branches and the severity of shading of the opposite crown half. The results collectively indicated that tree growth and branch and leaf acclimation responses of C. lanceolata are not only affected by the local light environment, but also by relative within-crown light conditions. We argue that such a non-autonomous branch response to changes in light conditions can improve whole-tree resource optimization. These results contribute to better understanding of tree growth and utilization of water and nitrogen under heterogeneous light conditions within tree canopies. PMID:26032625

  10. 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

  11. Dry matter and nitrogen accumulation are not affected by superoptimal concentration of ammonium in flowing solution culture with pH control

    NASA Technical Reports Server (NTRS)

    Rideout, J. W.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

    1994-01-01

    While it is known that superoptimal concentrations of the nitrate (NO3-) ion in solution culture do not increase NO3- uptake or dry matter accumulation, the same is not known for the ammonium (NH4+) ion. An experiment was conducted utilizing flowing solution culture with pH control to investigate the influence of superoptimal NH4+ concentrations on dry matter, nitrogen (N), potassium (K), calcium (Ca), and magnesium (Mg) accumulation by nonnodulated soybean plants. Increasing the NH4+ concentration in solution from 1 to 10 mM did not affect dry matter or N accumulation. Accumulations of K, Ca, and Mg were slightly decreased with increased NH4+ concentration. The NH4+ uptake system, which is saturated at less than 1mM NH4+, is able to regulate uptake of NH4+ at concentrations as high as 10 mM.

  12. Precursors and factors affecting formation of haloacetonitriles and chloropicrin during chlor(am)ination of nitrogenous organic compounds in drinking water.

    PubMed

    Jia, Aiyin; Wu, Chunde; Duan, Yan

    2016-05-01

    This study investigated the precursors and factors affecting formation of haloacetonitriles (HANs) and chloropicrin (TCNM) during chlorination/chloramination of eight amino acids in the effluent water of V-type clarifying filtration from a drinking water treatment plant. The yields of trichloroacetonitrile (TCAN), dichloroacetonitrile (DCAN) and TCNM were higher during chlorination than during chloramination. Tyrosine and tryptophan produced the greatest amount of DCAN and also generated a small amount of TCAN during chlorination process. Besides, the yields of DCAN were higher than TCNM during chlorination/chloramination. Contact time, Cl2:org-N molar ratios, pH, temperature and bromide ion affected nitrogenous disinfection by-products (N-DBPs) formation during chlorination of tryptophan in different degrees. TCAN, DCAN and TCNM formation showed the increasing and then decreasing with prolonged contact time. Higher Cl2:org-N molar ratios improved N-DBPs formation within a certain range. The pH affected N-DBPs formation differently. HANs increased with increasing pH from 5 to 6 and decreased with increasing pH from 6 to 9, while TCNM increased with increasing pH from 5 to 9. Higher temperatures enhanced TCNM formation, but reduced the formation of TCAN and DCAN. The presence of bromide ions improved the yields of HANs and TCNM and shifted N-DBPs to more brominated ones. PMID:26859617

  13. Soil carbon dioxide emission and carbon content as affected by irrigation, tillage, cropping system, and nitrogen fertilization.

    PubMed

    Sainju, Upendra M; Jabro, Jalal D; Stevens, William B

    2008-01-01

    Management practices can influence soil CO(2) emission and C content in cropland, which can effect global warming. We examined the effects of combinations of irrigation, tillage, cropping systems, and N fertilization on soil CO(2) flux, temperature, water, and C content at the 0- to 20-cm depth from May to November 2005 at two sites in the northern Great Plains. Treatments were two irrigation systems (irrigated vs. non-irrigated) and six management practices that contained tilled and no-tilled malt barley (Hordeum vulgaris L.) with 0 to 134 kg N ha(-1), no-tilled pea (Pisum sativum L.), and a conservation reserve program (CRP) planting applied in Lihen sandy loam (sandy, mixed, frigid, Entic Haplustolls) in western North Dakota. In eastern Montana, treatments were no-tilled malt barley with 78 kg N ha(-1), no-tilled rye (Secale cereale L.), no-tilled Austrian winter pea, no-tilled fallow, and tilled fallow applied in dryland Williams loam (fine-loamy, mixed Typic Argiborolls). Irrigation increased CO(2) flux by 13% compared with non-irrigation by increasing soil water content in North Dakota. Tillage increased CO(2) flux by 62 to 118% compared with no-tillage at both places. The flux was 1.5- to 2.5-fold greater with tilled than with non-tilled treatments following heavy rain or irrigation in North Dakota and 1.5- to 2.0-fold greater with crops than with fallow following substantial rain in Montana. Nitrogen fertilization increased CO(2) flux by 14% compared with no N fertilization in North Dakota and cropping increased the flux by 79% compared with fallow in no-till and 0 kg N ha(-1) in Montana. The CO(2) flux in undisturbed CRP was similar to that in no-tilled crops. Although soil C content was not altered, management practices influenced CO(2) flux within a short period due to changes in soil temperature, water, and nutrient contents. Regardless of irrigation, CO(2) flux can be reduced from croplands to a level similar to that in CRP planting using no

  14. Feed ingredients differing in fermentable fibre and indigestible protein content affect fermentation metabolites and faecal nitrogen excretion in growing pigs.

    PubMed

    Jha, R; Leterme, P

    2012-04-01

    To study the fermentation characteristics of different non-conventional dietary fibre (DF) sources with varying levels of indigestible CP content and their effects on the production of fermentation metabolites and on faecal nitrogen (N) excretion, an experiment was conducted with 40 growing pigs (initial BW 23 kg) using wheat bran (WB), pea hulls (PH), pea inner fibres (PIF), sugar beet pulp (SBP) or corn distillers dried grains with solubles (DDGS). The diets also contained soya protein isolate, pea starch and sucrose, and were supplemented with vitamin-mineral premix. Faecal samples were collected for 3 consecutive days from day 10, fed with added indigestible marker (chromic oxide) for 3 days from day 13 and pigs were slaughtered on day 16 from the beginning of the experiment. Digesta from the ileum and colon were collected and analysed for short-chain fatty acids (SCFA) and ammonia (NH3) content. The apparent total tract N digestibility was the lowest (P < 0.001) in diets based on DDGS (74%), medium in diets with WB and SBP (76% each) and highest in those with PIF and PH (79% and 81%, respectively). Expressed per kg fermented non-starch polysaccharides (NSP), faecal N excretion was higher with DDGS and WB diets (130 and 113 g/kg NSP fermented, respectively) and lower with PIF, PH and SBP diets (42, 52 and 55 g/kg NSP fermented, respectively). The PH-based diets had the highest (P < 0.05) SCFA concentrations, both in the ileum and the colon (27 and 122 mMol/kg digesta, respectively). The highest NH3 concentration was also found in the colon of pigs fed with PH (132 mMol/kg digesta). Loading plot of principle component analysis revealed that the CP : NSP ratio was positively related with faecal N excretion and NH3 concentration in colon contents, whereas negatively related with SCFA concentration in colon contents. In conclusion, pea fibres and SBP increased SCFA and reduced NH3 concentration in the pig's intestine and reduced faecal N excretion, which makes pea

  15. A systematic review of factors affecting children’s right to health in cluster randomized trials in Kenya

    PubMed Central

    2014-01-01

    Following the South African case, Treatment Action Campaign and Others v Minister of Health and Others, the use of 'pilot’ studies to investigate interventions already proven efficacious, offered free of charge to government, but confined by the government to a small part of the population, may violate children’s right to health, and the negative duty on governments not to prevent access to treatment. The applicants challenged a government decision to offer Nevirapine in a few pilot sites when evidence showed Nevirapine significantly reduced HIV transmission rates and despite donor offers of a free supply. The government refused to expand access, arguing they needed to collect more information, and citing concerns about long-term hazards, side effects, resistance and inadequate infrastructure. The court ruled this violated children’s right to health and asked the government to immediately expand access. Cluster randomized trials involving children are increasingly popular, and are often used to reduce 'contamination’: the possibility that members of a cluster adopt behavior of other clusters. However, they raise unique issues insufficiently addressed in literature and ethical guidelines. This case provides additional crucial guidance, based on a common human rights framework, for the Kenyan government and other involved stakeholders. Children possess special rights, often represent a 'captive’ group, and so motivate extra consideration. In a systematic review, we therefore investigated whether cluster trial designs are used to prevent or delay children’s access to treatment in Kenya or otherwise inconsistently with children’s right to health as outlined in the above case. Although we did not find state sponsored cluster trials, most had significant public sector involvement. Core obligations under children’s right to health were inadequately addressed across trials. Few cluster trials reported rationale for cluster randomization, offered post- trial

  16. Soil Tillage Management Affects Maize Grain Yield by Regulating Spatial Distribution Coordination of Roots, Soil Moisture and Nitrogen Status.

    PubMed

    Wang, Xinbing; Zhou, Baoyuan; Sun, Xuefang; Yue, Yang; Ma, Wei; Zhao, Ming

    2015-01-01

    The spatial distribution of the root system through the soil profile has an impact on moisture and nutrient uptake by plants, affecting growth and productivity. The spatial distribution of the roots, soil moisture, and fertility are affected by tillage practices. The combination of high soil density and the presence of a soil plow pan typically impede the growth of maize (Zea mays L.).We investigated the spatial distribution coordination of the root system, soil moisture, and N status in response to different soil tillage treatments (NT: no-tillage, RT: rotary-tillage, SS: subsoiling) and the subsequent impact on maize yield, and identify yield-increasing mechanisms and optimal soil tillage management practices. Field experiments were conducted on the Huang-Huai-Hai plain in China during 2011 and 2012. The SS and RT treatments significantly reduced soil bulk density in the top 0-20 cm layer of the soil profile, while SS significantly decreased soil bulk density in the 20-30 cm layer. Soil moisture in the 20-50 cm profile layer was significantly higher for the SS treatment compared to the RT and NT treatment. In the 0-20 cm topsoil layer, the NT treatment had higher soil moisture than the SS and RT treatments. Root length density of the SS treatment was significantly greater than density of the RT and NT treatments, as soil depth increased. Soil moisture was reduced in the soil profile where root concentration was high. SS had greater soil moisture depletion and a more concentration root system than RT and NT in deep soil. Our results suggest that the SS treatment improved the spatial distribution of root density, soil moisture and N states, thereby promoting the absorption of soil moisture and reducing N leaching via the root system in the 20-50 cm layer of the profile. Within the context of the SS treatment, a root architecture densely distributed deep into the soil profile, played a pivotal role in plants' ability to access nutrients and water. An optimal

  17. Soil Tillage Management Affects Maize Grain Yield by Regulating Spatial Distribution Coordination of Roots, Soil Moisture and Nitrogen Status

    PubMed Central

    Wang, Xinbing; Zhou, Baoyuan; Sun, Xuefang; Yue, Yang; Ma, Wei; Zhao, Ming

    2015-01-01

    The spatial distribution of the root system through the soil profile has an impact on moisture and nutrient uptake by plants, affecting growth and productivity. The spatial distribution of the roots, soil moisture, and fertility are affected by tillage practices. The combination of high soil density and the presence of a soil plow pan typically impede the growth of maize (Zea mays L.).We investigated the spatial distribution coordination of the root system, soil moisture, and N status in response to different soil tillage treatments (NT: no-tillage, RT: rotary-tillage, SS: subsoiling) and the subsequent impact on maize yield, and identify yield-increasing mechanisms and optimal soil tillage management practices. Field experiments were conducted on the Huang-Huai-Hai plain in China during 2011 and 2012. The SS and RT treatments significantly reduced soil bulk density in the top 0–20 cm layer of the soil profile, while SS significantly decreased soil bulk density in the 20–30 cm layer. Soil moisture in the 20–50 cm profile layer was significantly higher for the SS treatment compared to the RT and NT treatment. In the 0-20 cm topsoil layer, the NT treatment had higher soil moisture than the SS and RT treatments. Root length density of the SS treatment was significantly greater than density of the RT and NT treatments, as soil depth increased. Soil moisture was reduced in the soil profile where root concentration was high. SS had greater soil moisture depletion and a more concentration root system than RT and NT in deep soil. Our results suggest that the SS treatment improved the spatial distribution of root density, soil moisture and N states, thereby promoting the absorption of soil moisture and reducing N leaching via the root system in the 20–50 cm layer of the profile. Within the context of the SS treatment, a root architecture densely distributed deep into the soil profile, played a pivotal role in plants’ ability to access nutrients and water. An

  18. Sequencing and Transcriptional Analysis of the Streptococcus thermophilus Histamine Biosynthesis Gene Cluster: Factors That Affect Differential hdcA Expression▿ †

    PubMed Central

    Calles-Enríquez, Marina; Eriksen, Benjamin Hjort; Andersen, Pia Skov; Rattray, Fergal P.; Johansen, Annette H.; Fernández, María; Ladero, Victor; Alvarez, Miguel A.

    2010-01-01

    Histamine, a toxic compound that is formed by the decarboxylation of histidine through the action of microbial decarboxylases, can accumulate in fermented food products. From a total of 69 Streptococcus thermophilus strains screened, two strains, CHCC1524 and CHCC6483, showed the capacity to produce histamine. The hdc clusters of S. thermophilus CHCC1524 and CHCC6483 were sequenced, and the factors that affect histamine biosynthesis and histidine-decarboxylating gene (hdcA) expression were studied. The hdc cluster began with the hdcA gene, was followed by a transporter (hdcP), and ended with the hdcB gene, which is of unknown function. The three genes were orientated in the same direction. The genetic organization of the hdc cluster showed a unique organization among the lactic acid bacterial group and resembled those of Staphylococcus and Clostridium species, thus indicating possible acquisition through a horizontal transfer mechanism. Transcriptional analysis of the hdc cluster revealed the existence of a polycistronic mRNA covering the three genes. The histidine-decarboxylating gene (hdcA) of S. thermophilus demonstrated maximum expression during the stationary growth phase, with high expression levels correlated with high histamine levels. Limited expression was evident during the lag and exponential growth phases. Low-temperature (4°C) incubation of milk inoculated with a histamine-producing strain showed lower levels of histamine than did inoculated milk kept at 42°C. This reduction was attributed to a reduction in the activity of the HdcA enzyme itself rather than a reduction in gene expression or the presence of a lower cell number. PMID:20656875

  19. Importance of within-lake processes in affecting the dynamics of dissolved organic carbon and dissolved organic and inorganic nitrogen in an Adirondack forested lake/watershed

    NASA Astrophysics Data System (ADS)

    Kang, P.-G.; Mitchell, M. J.; McHale, P. J.; Driscoll, C. T.; McHale, M. R.; Inamdar, S.; Park, J.-H.

    2015-10-01

    Lakes nested in forested watersheds play important roles in mediating the concentrations and fluxes of dissolved organic matter. We compared long-term patterns of concentrations and fluxes of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and dissolved inorganic nitrogen (DIN) in the Arbutus Lake Watershed to evaluate how a lake nested in a forested watershed affects the dynamics of DOC and DON in the Adirondack Mountains of New York State, USA. We observed no significant long-term changes of concentrations and fluxes of DOC and DON in the Lake outlet since 1983 and 1994, respectively. However, the temporal patterns of DOC and DON concentrations in the Lake inlet showed significant seasonality such as increases during the vegetation-growing season along with notable decreases in the dormant season. A comparison of mass-balances between inlet and outlet for the period from 2000 to 2009 suggested that the Lake was a sink of DOC (mean of influx minus outflux: +1140 mol C ha-1 yr-1). In contrast, the difference of discharge-weighted DON concentrations (mean of inlet minus outlet: -1.0 μmol N L-1) between inlet and outlet was much smaller than the discharge-weighted DOC concentrations (average of inlet minus outlet: +87 μmol C L-1). DON fluxes showed considerable variation among years (mean of influx minus outflux: +8 mol N ha-1 yr-1; range of differences: -15 to 27 mol N ha-1 yr-1). DON exhibited low % retention ((influx - outflux) / influx) (mean: 6.9 %, range: -34.8 to +31.2) compared to DOC (mean: 30.1 %, range: +9.2 to +44.1). The resultant increase of DON within the lake was closely linked with a net decrease of DIN through monthly Pearson correlation analysis, suggesting the importance of biotic factors in mediating a lake DON dynamics. Our results show different relative retentions of DOC compared with DON, along with a larger retention of DIN than DON, suggesting that DOC and DON might display substantially different biogeochemical

  20. Formation of Metal Clusters or Nitrogen-Bridged Adducts by Reaction of a Bis(amino)stannylene with Halides of Two-Valent Transition Metals.

    PubMed

    Veith, Michael; Müller, Alice; Stahl, Lothar; Nötzel, Martin; Jarczyk, Maria; Huch, Volker

    1996-06-19

    When the cyclic bis(amino)stannylene Me(2)Si(NtBu)(2)Sn is allowed to react with metal halides MX(2) (M = Cr, Fe, Co, Zn; X = Cl, Br [Zn]) adducts of the general formula [Me(2)Si(NtBu)(2)Sn.MX(2)](n) are obtained. The compounds are generally dimeric (n = 2) except the ZnBr(2) adduct, which is monomeric in benzene. The crystal structures of [Me(2)Si(NtBu)(2)Sn.CoCl(2)](2) (triclinic, space group &Pmacr;1; a = 8.620(9) Å, b = 9.160(9) Å, c = 12.280(9) Å, alpha = 101.2(1) degrees, beta = 97.6(1) degrees, gamma = 105.9(1) degrees, Z = 1) and of [Me(2)Si(NtBu)(2)Sn.ZnCl(2)](2) (monoclinic, space group P2(1)/c; a = 8.156(9) Å, b = 16.835(12) Å, c = 13.206(9) Å, beta = 94.27(6) degrees, Z = 2) were determined by X-ray diffraction techniques. The two compounds form similar polycyclic, centrosymmetrical assemblies of metal atoms bridged by chlorine or nitrogen atoms. While in the case of the cobalt compound Co is pentacoordinated by three chlorine and two nitrogen atoms, in the zinc derivative Zn is almost tetrahedrally coordinated by three chlorine atoms and one nitrogen atom. The iron derivative [Me(2)Si(NtBu)(2)Sn.FeCl(2)](2) seems to be isostructural with the cobalt compound as can be deduced from the crystal data (triclinic, a = 8.622(7) Å, b = 9.158(8) Å, c = 12.353(8) Å, alpha = 101.8(1) degrees, beta = 96.9(1) degrees, gamma = 105.9(1) degrees, Z = 1). If NiBr(2), PdCl(2), or PtCl(2) is combined with the stannylene, the reaction product is totally different: 4 equiv of the stannylene are coordinating per metal halide, forming the molecular compound [Me(2)Si(NtBu)(2)Sn](4)MX(2), which crystallizes with half a mole of benzene per molecular formula. The crystal structures of [Me(2)Si(NtBu)(2)Sn](4).NiBr(2).(1)/(2)C(6)H(6) (tetragonal, space group I4(1)/a, a = b = 43.86(4) Å, c = 14.32(2) Å, Z = 16) and [Me(2)Si(NtBu)(2)Sn](4).PdCl(2).(1)/(2)C(6)H(6) (tetragonal, space group I4(1)/a, a = b = 43.99(4) Å, c = 14.318(14) Å, Z = 16) reveal the two compounds to

  1. Evaluation of a Classroom-Based Psychosocial Intervention in Conflict-Affected Nepal: A Cluster Randomized Controlled Trial

    ERIC Educational Resources Information Center

    Jordans, Mark J. D.; Komproe, Ivan H.; Tol, Wietse A.; Kohrt, Brandon A.; Luitel, Nagendra P.; Macy, Robert D.; de Jong, Joop T. V. M.

    2010-01-01

    Background: In situations of ongoing violence, childhood psychosocial and mental health problems require care. However, resources and evidence for adequate interventions are scarce for children in low- and middle-income countries. This study evaluated a school-based psychosocial intervention in conflict-affected, rural Nepal. Methods: A cluster…

  2. 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. PMID:25407697

  3. Does the spatial arrangement of disturbance within forested watersheds affect loadings of nitrogen to stream waters? A test using Landsat and synoptic stream water data

    NASA Astrophysics Data System (ADS)

    Cowles, Travis R.; McNeil, Brenden E.; Eshleman, Keith N.; Deel, Lindsay N.; Townsend, Philip A.

    2014-02-01

    Remotely sensed maps of forest disturbance provide a powerful tool for predicting spatial and temporal variability in the loading of nitrogen to receiving waters, key data needed for effective watershed management of nutrient pollution. We hypothesize that the spatial arrangement of disturbances within small-forested watersheds can affect N loadings. To test this, we developed schemes for spatially weighting maps of yearly disturbance produced through change analysis of the Landsat Tasseled Cap Disturbance Index (DI), and evaluated the ability of each scheme to predict N concentrations, and subsequently estimated N loads, from forty low-order streams within the Savage River drainage of western Maryland, USA during the 2006-2010 water years, a period encompassing extensive defoliations by gypsy moths (Lymantria dispar). We generated a base scheme of unweighted, watershed averaged change in DI (ΔDI), and five other schemes that weighted ΔDI by either a pixel's flow accumulation value, the distance to the watershed outlet, or proximity to the stream. Over the five years, the flow accumulation scheme tended to perform better than other weighting schemes, and even explained slightly more variability than the base scheme during years of moderate N loads (R2 = 0.15 vs. 0.03 in 2007 and R2 = 0.30 vs. 0.18 in 2010). However, this best spatial weighting scheme explained comparable or less variability during the two post-defoliation years with larger N loads (R2 = 0.43 vs. 0.44 in 2008 and R2 = 0.31 vs. 0.48 in 2009). Thus, for the purposes of utilizing remote sensing information within watershed management of nutrient pollution, these results suggest that coarse-scale, high temporal frequency data such as MODIS could be well suited for characterizing forest disturbance and predicting the resultant episodic N loads.

  4. Carbon-to-nitrogen ratio affects the biomass composition and the fatty acid profile of heterotrophically grown Chlorella sp. TISTR 8990 for biodiesel production.

    PubMed

    Singhasuwan, Somruethai; Choorit, Wanna; Sirisansaneeyakul, Sarote; Kokkaew, Nakhon; Chisti, Yusuf

    2015-12-20

    Chlorella sp. TISTR 8990 was cultivated heterotrophically in media with various initial carbon-to-nitrogen ratios (C/N ratio) and at different agitation speeds. The production of the biomass, its total fatty acid content and the composition of the fatty acids were affected by the C/N ratio, but not by agitation speed in the range examined. The biomass production was maximized at a C/N mass ratio of 29:1. At this C/N ratio, the biomass productivity was 0.68gL(-1)d(-1), or nearly 1.6-fold the best attainable productivity in photoautotrophic growth. The biomass yield coefficient on glucose was 0.62gg(-1) during exponential growth. The total fatty acids (TFAs) in the freeze-dried biomass were maximum (459mgg(-1)) at a C/N ratio of 95:1. Lower values of the C/N ratio reduced the fatty acid content of the biomass. The maximum productivity of TFAs (186mgL(-1)d(-1)) occurred at C/N ratios of 63:1 and higher. At these conditions, the fatty acids were mostly of the polyunsaturated type. Allowing the alga to remain in the stationary phase for a prolonged period after N-depletion, reduced the level of monounsaturated fatty acids and the level of polyunsaturated fatty acids increased. Biotin supplementation of the culture medium reduced the biomass productivity relative to biotin-free control, but had no effect on the total fatty acid content of the biomass. PMID:26467713

  5. Genotypic Tannin Levels in Populus tremula Impact the Way Nitrogen Enrichment Affects Growth and Allocation Responses for Some Traits and Not for Others

    PubMed Central

    Bandau, Franziska; Decker, Vicki Huizu Guo; Gundale, Michael J.; Albrectsen, Benedicte Riber

    2015-01-01

    Plant intraspecific variability has been proposed as a key mechanism by which plants adapt to environmental change. In boreal forests where nitrogen availability is strongly limited, nitrogen addition happens indirectly through atmospheric N deposition and directly through industrial forest fertilization. These anthropogenic inputs of N have numerous environmental consequences, including shifts in plant species composition and reductions in plant species diversity. However, we know less about how genetic differences within plant populations determine how species respond to eutrophication in boreal forests. According to plant defense theories, nitrogen addition will cause plants to shift carbon allocation more towards growth and less to chemical defense, potentially enhancing vulnerability to antagonists. Aspens are keystone species in boreal forests that produce condensed tannins to serve as chemical defense. We conducted an experiment using ten Populus tremula genotypes from the Swedish Aspen Collection that express extreme levels of baseline investment into foliar condensed tannins. We investigated whether investment into growth and phenolic defense compounds in young plants varied in response to two nitrogen addition levels, corresponding to atmospheric N deposition and industrial forest fertilization. Nitrogen addition generally caused growth to increase, and tannin levels to decrease; however, individualistic responses among genotypes were found for height growth, biomass of specific tissues, root:shoot ratios, and tissue lignin and N concentrations. A genotype’s baseline ability to produce and store condensed tannins also influenced plant responses to N, although this effect was relatively minor. High-tannin genotypes tended to grow less biomass under low nitrogen levels and more at the highest fertilization level. Thus, the ability in aspen to produce foliar tannins is likely associated with a steeper reaction norm of growth responses, which suggests a

  6. Genotypic Tannin Levels in Populus tremula Impact the Way Nitrogen Enrichment Affects Growth and Allocation Responses for Some Traits and Not for Others.

    PubMed

    Bandau, Franziska; Decker, Vicki Huizu Guo; Gundale, Michael J; Albrectsen, Benedicte Riber

    2015-01-01

    Plant intraspecific variability has been proposed as a key mechanism by which plants adapt to environmental change. In boreal forests where nitrogen availability is strongly limited, nitrogen addition happens indirectly through atmospheric N deposition and directly through industrial forest fertilization. These anthropogenic inputs of N have numerous environmental consequences, including shifts in plant species composition and reductions in plant species diversity. However, we know less about how genetic differences within plant populations determine how species respond to eutrophication in boreal forests. According to plant defense theories, nitrogen addition will cause plants to shift carbon allocation more towards growth and less to chemical defense, potentially enhancing vulnerability to antagonists. Aspens are keystone species in boreal forests that produce condensed tannins to serve as chemical defense. We conducted an experiment using ten Populus tremula genotypes from the Swedish Aspen Collection that express extreme levels of baseline investment into foliar condensed tannins. We investigated whether investment into growth and phenolic defense compounds in young plants varied in response to two nitrogen addition levels, corresponding to atmospheric N deposition and industrial forest fertilization. Nitrogen addition generally caused growth to increase, and tannin levels to decrease; however, individualistic responses among genotypes were found for height growth, biomass of specific tissues, root:shoot ratios, and tissue lignin and N concentrations. A genotype's baseline ability to produce and store condensed tannins also influenced plant responses to N, although this effect was relatively minor. High-tannin genotypes tended to grow less biomass under low nitrogen levels and more at the highest fertilization level. Thus, the ability in aspen to produce foliar tannins is likely associated with a steeper reaction norm of growth responses, which suggests a

  7. Tuning the charge state of Ag and Au atoms and clusters deposited on oxide surfaces by doping: a DFT study of the adsorption properties of nitrogen- and niobium-doped TiO2 and ZrO2.

    PubMed

    Schlexer, Philomena; Ruiz Puigdollers, Antonio; Pacchioni, Gianfranco

    2015-09-14

    The charge state of Ag and Au atoms and clusters (Ag4 and Au4, Ag5 and Au5) adsorbed on defective TiO2 anatase(101) and tetragonal ZrO2(101) has been systematically investigated as a function of oxide doping and defectivity using a DFT+U approach. As intrinsic defects, we have considered the presence of oxygen vacancies. As extrinsic defects, substitutional nitrogen- and niobium-doping have been investigated, respectively. Both surface and sub-surface defects and dopants have been considered. Whereas on surfaces with oxygen vacancies or Nb-doping, atoms and clusters may become negatively charged, N-doping always leads to the formation of positively charged adsorbates, independently of the supporting material (TiO2 or ZrO2). This suggests the possibility to tune the electronic properties of supported metal clusters by selective doping of the oxide support, an effect that may result in complete changes in chemical reactivity. PMID:26248205

  8. Importance of within-lake processes in affecting the dynamics of dissolved organic carbon and dissolved organic and inorganic nitrogen in an Adirondack forested lake/watershed

    NASA Astrophysics Data System (ADS)

    Kang, Phil-Goo; Mitchell, Myron J.; McHale, Patrick J.; Driscoll, Charles T.; Inamdar, Shreeram; Park, Ji-Hyung

    2016-05-01

    Lakes nested in forested watersheds play an important role in mediating the concentrations and fluxes of dissolved organic matter. We compared long-term patterns of concentrations and fluxes of dissolved organic carbon (DOC) and dissolved organic (DON) and inorganic nitrogen (DIN) in aquatic ecosystems of the Arbutus Lake watershed to evaluate how a lake nested in a forested watershed affects the sources (e.g., production) and sinks (e.g., retention) of DOC and DON in the Adirondack Mountains of New York, USA. We observed no significant long-term changes of DOC and DON in the lake outlet since 1983 and 1994, respectively. However, the temporal patterns of DOC and DON concentrations in the lake inlet showed significant seasonality such as increases during the vegetation-growing season along with notable decreases in the dormant season. A comparison of mass balances between inlet and outlet for the period from 2000 to 2009 suggested that the lake was a sink of DOC (mean of influx minus outflux: +1140 mol C ha-1 yr-1). In contrast, the difference of discharge-weighted DON concentrations (mean of inlet minus outlet: -1.0 µmol N L-1) between inlet and outlet was much smaller than the discharge-weighted DOC concentrations (average of inlet minus outlet: + 87 µmol C L-1). DON fluxes showed considerable variation among years (mean of influx minus outflux: +8 mol N ha-1 yr-1; range of differences: -15 to 27 mol N ha-1 yr-1). DON exhibited low percent retention ((influx-outflux)/influx) (mean: 6.9 %, range: -34.8 to +31.2) compared to DOC (mean: 30.1 %, range: +9.2 to +44.1). The resultant increase of DON within the lake was closely linked with a net decrease of DIN through monthly Pearson correlation analysis, suggesting the importance of biotic factors in mediating lake DON dynamics. Our results show different relative retentions of DOC compared with DON, along with a larger retention of DIN than DON, suggesting that DOC and DON might display substantially different

  9. The application of ascorbate or its immediate precursor, galactono-1,4-lactone, does not affect the response of nitrogen-fixing pea nodules to water stress.

    PubMed

    Zabalza, Ana; Gálvez, Loli; Marino, Daniel; Royuela, Mercedes; Arrese-Igor, Cesar; González, Esther M

    2008-05-26

    Nitrogen fixation in legumes is dramatically inhibited by abiotic stresses, and this reduction is often associated with oxidative damage. Although ascorbate (ASC) has been firmly associated with antioxidant defence, recent studies have suggested that the functions of ASC are related primarily to developmental processes. This study examines the hypothesis that ASC is involved in alleviating the oxidative damage to nodules caused by an increase in reactive oxygen species (ROS) under water stress. The hypothesis was tested by supplying 5mM ASC to pea plants (Pisum sativum L.) experiencing moderate water stress (ca. -1 MPa) and monitoring plant responses in relation to those experiencing the same water stress without ASC. A supply of exogenous ASC increased the nodule ASC+dehydroascorbate (DHA) pool compared to water-stressed nodules without ASC, and significantly modulated the response to water stress of the unspecific guaiacol peroxidase (EC 1.11.1.7) in leaves and nodules. However, ASC supply did not produce recovery from water stress in other nodule antioxidant enzymes, nodule carbon and nitrogen enzymes, or nitrogen fixation. The supply of the immediate ASC precursor, galactono-1,4-lactone (GL), increased the nodule ASC+DHA pool, but also failed to prevent the decline of nitrogen fixation and the reduction of carbon flux in nodules. These results suggest that ASC has a limited role in preventing the negative effects of water stress on nodule metabolism and nitrogen fixation. PMID:17931744

  10. Working with men to prevent intimate partner violence in a conflict-affected setting: a pilot cluster randomized controlled trial in rural Côte d’Ivoire

    PubMed Central

    2014-01-01

    Background Evidence from armed conflict settings points to high levels of intimate partner violence (IPV) against women. Current knowledge on how to prevent IPV is limited—especially within war-affected settings. To inform prevention programming on gender-based violence in settings affected by conflict, we evaluated the impact of adding a targeted men’s intervention to a community-based prevention programme in Côte d’Ivoire. Methods We conducted a two-armed, non-blinded cluster randomized trial in Côte d’Ivoire among 12 pair-matched communities spanning government-controlled, UN buffer, and rebel–controlled zones. The intervention communities received a 16-week IPV prevention intervention using a men’s discussion group format. All communities received community-based prevention programmes. Baseline data were collected from couples in September 2010 (pre-intervention) and follow-up in March 2012 (one year post-intervention). The primary trial outcome was women’s reported experiences of physical and/or sexual IPV in the last 12 months. We also assessed men’s reported intention to use physical IPV, attitudes towards sexual IPV, use of hostility and conflict management skills, and participation in gendered household tasks. An adjusted cluster-level intention to treat analysis was used to compare outcomes between intervention and control communities at follow-up. Results At follow-up, reported levels of physical and/or sexual IPV in the intervention arm had decreased compared to the control arm (ARR 0.52, 95% CI 0.18-1.51, not significant). Men participating in the intervention reported decreased intentions to use physical IPV (ARR 0.83, 95% CI 0.66-1.06) and improved attitudes toward sexual IPV (ARR 1.21, 95% CI 0.77-1.91). Significant differences were found between men in the intervention and control arms’ reported ability to control their hostility and manage conflict (ARR 1.3, 95% CI 1.06-1.58), and participation in gendered household tasks (ARR

  11. Transcriptional Profiling Identifies a Role for BrlA in the Response to Nitrogen Depletion and for StuA in the Regulation of Secondary Metabolite Clusters in Aspergillus fumigatus▿ ‡

    PubMed Central

    Twumasi-Boateng, Kwame; Yu, Yan; Chen, Dan; Gravelat, Fabrice N.; Nierman, William C.; Sheppard, Donald C.

    2009-01-01

    Conidiation (asexual sporulation) is a key developmental process in filamentous fungi. We examined the gene regulatory roles of the Aspergillus fumigatus developmental transcription factors StuAp and BrlAp during conidiation. Conidiation was completely abrogated in an A. fumigatus ΔbrlA mutant and was severely impaired in a ΔstuA mutant. We determined the full genome conidiation transcriptomes of wild-type and ΔbrlA and ΔstuA mutant A. fumigatus and found that BrlAp and StuAp governed overlapping but distinct transcriptional programs. Six secondary metabolite biosynthetic clusters were found to be regulated by StuAp, while only one cluster exhibited BrlAp-dependent expression. The ΔbrlA mutant, but not the ΔstuA mutant, had impaired downregulation of genes encoding ribosomal proteins under nitrogen-limiting, but not carbon-limiting, conditions. Interestingly, inhibition of the target of rapamycin (TOR) pathway also caused downregulation of ribosomal protein genes in both the wild-type strain and the ΔbrlA mutant. Downregulation of these genes by TOR inhibition was associated with conidiation in the wild-type strain but not in the ΔbrlA mutant. Therefore, BrlAp-mediated repression of ribosomal protein gene expression is not downstream of the TOR pathway. Furthermore, inhibition of ribosomal protein gene expression is not sufficient to induce conidiation in the absence of BrlAp. PMID:19028996

  12. Targeted enhancement of glutamate-to-γ-aminobutyrate conversion in Arabidopsis seeds affects carbon-nitrogen balance and storage reserves in a development-dependent manner.

    PubMed

    Fait, Aaron; Nesi, Adriano Nunes; Angelovici, Ruthie; Lehmann, Martin; Pham, Phuong Anh; Song, Luhua; Haslam, Richard P; Napier, Johnathan A; Galili, Gad; Fernie, Alisdair R

    2011-11-01

    In seeds, glutamate decarboxylase (GAD) operates at the metabolic nexus between carbon and nitrogen metabolism by catalyzing the unidirectional decarboxylation of glutamate to form γ-aminobutyric acid (GABA). To elucidate the regulatory role of GAD in seed development, we generated Arabidopsis (Arabidopsis thaliana) transgenic plants expressing a truncated GAD from Petunia hybrida missing the carboxyl-terminal regulatory Ca(2+)-calmodulin-binding domain under the transcriptional regulation of the seed maturation-specific phaseolin promoter. Dry seeds of the transgenic plants accumulated considerable amounts of GABA, and during desiccation the content of several amino acids increased, although not glutamate or proline. Dry transgenic seeds had higher protein content than wild-type seeds but lower amounts of the intermediates of glycolysis, glycerol and malate. The total fatty acid content of the transgenic seeds was 50% lower than in the wild type, while acyl-coenzyme A accumulated in the transgenic seeds. Labeling experiments revealed altered levels of respiration in the transgenic seeds, and fractionation studies indicated reduced incorporation of label in the sugar and lipid fractions extracted from transgenic seeds. Comparative transcript profiling of the dry seeds supported the metabolic data. Cellular processes up-regulated at the transcript level included the tricarboxylic acid cycle, fatty acid elongation, the shikimate pathway, tryptophan metabolism, nitrogen-carbon remobilization, and programmed cell death. Genes involved in the regulation of germination were similarly up-regulated. Taken together, these results indicate that the GAD-mediated conversion of glutamate to GABA during seed development plays an important role in balancing carbon and nitrogen metabolism and in storage reserve accumulation. PMID:21921115

  13. Adsorption of nitrogen oxide molecules to the surface of nanosized nickel clusters formed on the (111) surface of a magnesium oxide film

    NASA Astrophysics Data System (ADS)

    Remar, D. F.; Turiev, A. M.; Tsidaeva, N. I.; Magkoev, T. T.

    2010-10-01

    The properties of the systems formed on deposition of Ni atoms on the (111) surface of a MgO film of thickness equal to six monomolecular layers grown on a Mo(110) crystal face and the adsorption of NO nitrogen oxide molecules to the system surface have been studied by methods of electron spectroscopy (AES, XPES, LEED, LEIBSS) and reflective infrared absorption spectroscopy. On deposition of Ni atoms on the surface of MgO at a substrate temperature of 600 K, three-dimensional islands of Ni are formed. The subsequent adsorption of NO results in molecule dissociation even at 110 K. The efficiency of this process depends on the morphology of the Ni layer.

  14. Pseudomonas aeruginosa mutants affected in anaerobic growth on arginine: evidence for a four-gene cluster encoding the arginine deiminase pathway.

    PubMed Central

    Vander Wauven, C; Piérard, A; Kley-Raymann, M; Haas, D

    1984-01-01

    Pseudomonas aeruginosa PAO was able to grow in the absence of exogenous terminal electron acceptors, provided that the medium contained 30 to 40 mM L-arginine and 0.4% yeast extract. Under strictly anaerobic conditions (O2 at less than 1 ppm), growth could be measured as an increase in protein and proceeded in a non-exponential way; arginine was largely converted to ornithine but not entirely consumed at the end of growth. In the GasPak anaerobic jar (Becton Dickinson and Co.), the wild-type strain PAO1 grew on arginine-yeast extract medium in 3 to 5 days; mutants could be isolated that were unable to grow under these conditions. All mutants (except one) were defective in at least one of the three enzymes of the arginine deiminase pathway (arcA, arcB, and arcC mutants) or in a novel function that might be involved in anaerobic arginine uptake (arcD mutants). The mutations arcA (arginine deiminase), arcB (catabolic ornithine carbamoyltransferase), arcC (carbamate kinase), and arcD were highly cotransducible and mapped in the 17-min chromosome region. Some mutations in the arc cluster led to low, noninducible levels of all three arginine deiminase pathway enzymes and thus may affect control elements required for induction of the postulated arc operon. Two fluorescent pseudomonads (P. putida and P. fluorescens) and P. mendocina, as well as one PAO mutant, possessed an inducible arginine deiminase pathway and yet were unable to grow fermentatively on arginine. The ability to use arginine-derived ATP for growth may provide P. aeruginosa with a selective advantage when oxygen and nitrate are scarce. PMID:6438064

  15. Outcomes and moderators of a preventive school-based mental health intervention for children affected by war in Sri Lanka: a cluster randomized trial

    PubMed Central

    TOL, WIETSE A.; KOMPROE, IVAN H.; JORDANS, MARK J.D.; VALLIPURAM, ANAVARATHAN; SIPSMA, HEATHER; SIVAYOKAN, SAMBASIVAMOORTHY; MACY, ROBERT D.; DE JONG, JOOP T.

    2012-01-01

    We aimed to examine outcomes, moderators and mediators of a preventive school-based mental health intervention implemented by paraprofessionals in a war-affected setting in northern Sri Lanka. A cluster randomized trial was employed. Subsequent to screening 1,370 children in randomly selected schools, 399 children were assigned to an intervention (n=199) or waitlist control condition (n=200). The intervention consisted of 15 manualized sessions over 5 weeks of cognitive behavioral techniques and creative expressive elements. Assessments took place before, 1 week after, and 3 months after the intervention. Primary outcomes included post-traumatic stress disorder (PTSD), depressive, and anxiety symptoms. No main effects on primary outcomes were identified. A main effect in favor of intervention for conduct problems was observed. This effect was stronger for younger children. Furthermore, we found intervention benefits for specific subgroups. Stronger effects were found for boys with regard to PTSD and anxiety symptoms, and for younger children on pro-social behavior. Moreover, we found stronger intervention effects on PTSD, anxiety, and function impairment for children experiencing lower levels of current war-related stressors. Girls in the intervention condition showed smaller reductions on PTSD symptoms than waitlisted girls. We conclude that preventive school-based psychosocial interventions in volatile areas characterized by ongoing war-related stressors may effectively improve indicators of psychological wellbeing and posttraumatic stress-related symptoms in some children. However, they may undermine natural recovery for others. Further research is necessary to examine how gender, age and current war-related experiences contribute to differential intervention effects. PMID:22654944

  16. Richness, biomass, and nutrient content of a wetland macrophyte community affect soil nitrogen cycling in a diversity-ecosystem functioning experiment

    USGS Publications Warehouse

    Korol, Alicia R.; Ahn, Changwoo; Noe, Gregory

    2016-01-01

    The development of soil nitrogen (N) cycling in created wetlands promotes the maturation of multiple biogeochemical cycles necessary for ecosystem functioning. This development proceeds from gradual changes in soil physicochemical properties and influential characteristics of the plant community, such as competitive behavior, phenology, productivity, and nutrient composition. In the context of a 2-year diversity experiment in freshwater mesocosms (0, 1, 2, 3, or 4 richness levels), we assessed the direct and indirect impacts of three plant community characteristics – species richness, total biomass, and tissue N concentration – on three processes in the soil N cycle – soil net ammonification, net nitrification, and denitrification potentials. Species richness had a positive effect on net ammonification potential (NAP) through higher redox potentials and likely faster microbial respiration. All NAP rates were negative, however, due to immobilization and high rates of ammonium removal. Net nitrification was inhibited at higher species richness without mediation from the measured soil properties. Higher species richness also inhibited denitrification potential through increased redox potential and decreased nitrification. Both lower biomass and/or higher tissue ratios of carbon to nitrogen, characteristics indicative of the two annual plants, were shown to have stimulatory effects on all three soil N processes. The two mediating physicochemical links between the young macrophyte community and microbial N processes were soil redox potential and temperature. Our results suggest that early-successional annual plant communities play an important role in the development of ecosystem N multifunctionality in newly created wetland soils.

  17. A 6-Year-Long Manipulation with Soil Warming and Canopy Nitrogen Additions does not Affect Xylem Phenology and Cell Production of Mature Black Spruce.

    PubMed

    Dao, Madjelia C E; Rossi, Sergio; Walsh, Denis; Morin, Hubert; Houle, Daniel

    2015-01-01

    The predicted climate warming and increased atmospheric inorganic nitrogen deposition are expected to have dramatic impacts on plant growth. However, the extent of these effects and their interactions remains unclear for boreal forest trees. The aim of this experiment was to investigate the effects of increased soil temperature and nitrogen (N) depositions on stem intra-annual growth of two mature stands of black spruce [Picea mariana (Mill.) BSP] in Québec, QC, Canada. During 2008-2013, the soil around mature trees was warmed up by 4°C with heating cables during the growing season and precipitations containing three times the current inorganic N concentration were added by frequent canopy applications. Xylem phenology and cell production were monitored weekly from April to October. The 6-year-long experiment performed in two sites at different altitude showed no substantial effect of warming and N-depositions on xylem phenological phases of cell enlargement, wall thickening and lignification. Cell production, in terms of number of tracheids along the radius, also did not differ significantly and followed the same patterns in control and treated trees. These findings allowed the hypothesis of a medium-term effect of soil warming and N depositions on the growth of mature black spruce to be rejected. PMID:26617610

  18. A 6-Year-Long Manipulation with Soil Warming and Canopy Nitrogen Additions does not Affect Xylem Phenology and Cell Production of Mature Black Spruce

    PubMed Central

    Dao, Madjelia C. E.; Rossi, Sergio; Walsh, Denis; Morin, Hubert; Houle, Daniel

    2015-01-01

    The predicted climate warming and increased atmospheric inorganic nitrogen deposition are expected to have dramatic impacts on plant growth. However, the extent of these effects and their interactions remains unclear for boreal forest trees. The aim of this experiment was to investigate the effects of increased soil temperature and nitrogen (N) depositions on stem intra-annual growth of two mature stands of black spruce [Picea mariana (Mill.) BSP] in Québec, QC, Canada. During 2008–2013, the soil around mature trees was warmed up by 4°C with heating cables during the growing season and precipitations containing three times the current inorganic N concentration were added by frequent canopy applications. Xylem phenology and cell production were monitored weekly from April to October. The 6-year-long experiment performed in two sites at different altitude showed no substantial effect of warming and N-depositions on xylem phenological phases of cell enlargement, wall thickening and lignification. Cell production, in terms of number of tracheids along the radius, also did not differ significantly and followed the same patterns in control and treated trees. These findings allowed the hypothesis of a medium-term effect of soil warming and N depositions on the growth of mature black spruce to be rejected. PMID:26617610

  19. Tensile Deformation Behavior and Phase Transformation in the Weld Coarse-Grained Heat-Affected Zone of Metastable High-Nitrogen Fe-18Cr-10Mn-N Stainless Steel

    NASA Astrophysics Data System (ADS)

    Moon, Joonoh; Lee, Tae-Ho; Park, Seong-Jun; Jang, Jae-il; Jang, Min-Ho; Ha, Heon-Young; Hwang, Byoungchul

    2013-07-01

    The tensile deformation behavior and phase transformation in the weld coarse-grained heat-affected zone (CGHAZ) of a metastable high-nitrogen austenitic stainless steel was explored through tensile tests, nanoindentation experiments, and transmission electron microscopy analysis. True stress-strain response during tensile test was found to be seriously affected by δ-ferrite fraction, which depends on peak temperature of the CGHAZs. The strain-induced martensitic transformation (SIMT) occurred in base steel, whereas the SIMT disappeared and deformation twinning occurred predominantly in the CGHAZs. The relationship among true stress-strain response, nanoindentation hardness, and deformed microstructures was carefully investigated and discussed in terms of changes of stacking fault energy.

  20. Sequences of nifX, nifW, nifZ, nifB and two ORF in the Frankia nitrogen fixation gene cluster.

    PubMed

    Harriott, O T; Hosted, T J; Benson, D R

    1995-08-01

    The actinomycete Frankia alni fixes N2 in root nodules of several non-leguminous plants. It is one of the few known N2-fixing members of the high-GC Gram+ lineage of prokaryotes. Thus, we have undertaken a study of its nitrogen fixation gene (nif) organization to compare with that of the more extensively characterized proteobacteria. A cosmid (pFN1) containing the nif region of Fa CpI1 was isolated from a cosmid library using the nifHDK genes of Fa CpI1 as a probe. A 4.5-kb BamHI fragment that mapped downstream from the previously characterized nifHDK genes was cloned and sequenced. Based on nt and aa sequence similarities to nif from other N2-fixing bacteria, eight ORF were identified and designated nifX, orf3, orf1, nifW, nifZ, nifB, orf2 and nifU. A region that hybridized to Rhizobium meliloti and Klebsiella pneumoniae nifA did not appear to contain a nifA-like gene. We have revised the map of the Fa nif region to reflect current information. PMID:7642138

  1. Modeling forest development after fire disturbance: Climate, soil organic layer, and nitrogen jointly affect forest canopy species and long-term ecosystem carbon accumulation in the North American boreal forest

    NASA Astrophysics Data System (ADS)

    Trugman, A. T.; Fenton, N.; Bergeron, Y.; Xu, X.; Welp, L.; Medvigy, D.

    2015-12-01

    Soil organic layer dynamics strongly affect boreal forest development after fire. Field studies show that soil organic layer thickness exerts a species-specific control on propagule establishment in the North American boreal forest. On organic soils thicker than a few centimeters, all propagules are less able to recruit, but broadleaf trees recruit less effectively than needleleaf trees. In turn, forest growth controls organic layer accumulation through modulating litter input and litter quality. These dynamics have not been fully incorporated into models, but may be essential for accurate projections of ecosystem carbon storage. Here, we develop a data-constrained model for understanding boreal forest development after fire. We update the ED2 model to include new aspen and black spruce species-types, species-specific propagule survivorship dependent on soil organic layer depth, species-specific litter decay rates, dynamically accumulating moss and soil organic layers, and nitrogen fixation by cyanobacteria associated with moss. The model is validated against diverse observations ranging from monthly to centennial timescales and spanning a climate gradient in Alaska, central Canada, and Quebec. We then quantify differences in forest development that result from changes in organic layer accumulation, temperature, and nitrogen. We find that (1) the model accurately reproduces a range of observations throughout the North American boreal forest; (2) the presence of a thick organic layer results in decreased decomposition and decreased aboveground productivity, effects that can increase or decrease ecosystem carbon uptake depending on location-specific attributes; (3) with a mean warming of 4°C, some forests switch from undergoing succession to needleleaf forests to recruiting multiple cohorts of broadleaf trees, decreasing ecosystem accumulation by ~30% after 300 years; (4) the availability of nitrogen regulates successional dynamics such than broadleaf species are

  2. Net global warming potential and greenhouse gas intensity in a double-cropping cereal rotation as affected by nitrogen and straw management

    NASA Astrophysics Data System (ADS)

    Huang, T.; Gao, B.; Christie, P.; Ju, X.

    2013-12-01

    The effects of nitrogen and straw management on global warming potential (GWP) and greenhouse gas intensity (GHGI) in a winter wheat-summer maize double-cropping system on the North China Plain were investigated. We measured nitrous oxide (N2O) emissions and studied net GWP (NGWP) and GHGI by calculating the net exchange of CO2 equivalent (CO2-eq) from greenhouse gas emissions, agricultural inputs and management practices, as well as changes in soil organic carbon (SOC), based on a long-term field experiment established in 2006. The field experiment includes six treatments with three fertilizer N levels (zero N (control), optimum and conventional N) and straw removal (i.e. N0, Nopt and Ncon) or return (i.e. SN0, SNopt and SNcon). Optimum N management (Nopt, SNopt) saved roughly half of the fertilizer N compared to conventional agricultural practice (Ncon, SNcon), with no significant effect on grain yields. Annual mean N2O emissions reached 3.90 kg N2O-N ha-1 in Ncon and SNcon, and N2O emissions were reduced by 46.9% by optimizing N management of Nopt and SNopt. Straw return increased annual mean N2O emissions by 27.9%. Annual SOC sequestration was 0.40-1.44 Mg C ha-1 yr-1 in plots with N application and/or straw return. Compared to the conventional N treatments the optimum N treatments reduced NGWP by 51%, comprising 25% from decreasing N2O emissions and 75% from reducing N fertilizer application rates. Straw return treatments reduced NGWP by 30% compared to no straw return because the GWP from increments of SOC offset the GWP from higher emissions of N2O, N fertilizer and fuel after straw return. The GHGI trends from the different nitrogen and straw management practices were similar to the NGWP. In conclusion, optimum N and straw return significantly reduced NGWP and GHGI and concomitantly achieved relatively high grain yields in this important winter wheat-summer maize double-cropping system.

  3. Net global warming potential and greenhouse gas intensity in a double cropping cereal rotation as affected by nitrogen and straw management

    NASA Astrophysics Data System (ADS)

    Huang, T.; Gao, B.; Christie, P.; Ju, X.

    2013-08-01

    The effects of nitrogen and straw management on global warming potential (GWP) and greenhouse gas intensity (GHGI) in a winter wheat-summer maize double-cropping system on the North China Plain were investigated. We measured nitrous oxide (N2O) emissions and studied net GWP (NGWP) and GHGI by calculating the net exchange of CO2 equivalent (CO2-eq) from greenhouse gas emissions, agricultural inputs and management practices, and changes in soil organic carbon (SOC), based on a long-term field experiment established in 2006. The field experiment includes six treatments with three fertilizer N levels (zero-N control, optimum and conventional N) and straw removal (i.e. N0, Nopt and Ncon) or return (i.e. N0, Nopt and SNcon). Optimum N management (Nopt, SNopt) saved roughly half of the fertilizer N compared to conventional agricultural practice (Ncon, SNcon) with no significant effect on grain yields. Annual mean N2O emissions reached 3.90 kg N2O-N ha-1 in Ncon and SNcon, and N2O emissions were reduced by 46.9% by optimizing N management of Nopt and SNopt. Straw return increased annual mean N2O emissions by 27.9%. Annual SOC sequestration was 0.40-1.44 Mg C ha-1 yr-1 in plots with N application and/or straw return. Compared to the conventional N treatments the optimum N treatments reduced NGWP by 51%, comprising 25% from decreasing N2O emissions and 75% from reducing N fertilizer application rates. Straw return treatments reduced NGWP by 30% compared to no straw return because the GWP from increments of SOC offset the GWP from higher emissions of N2O, N fertilizer and fuel after straw return. The GHGI trends from the different nitrogen and straw management practices were similar to the NGWP. In conclusion, optimum N and straw return significantly reduced NGWP and GHGI and concomitantly achieved relatively high grain yields in this important winter wheat-summer maize double-cropping system.

  4. A new measurement of the fusion reaction nitrogen- 14(proton,photon)oxygen-15 and its impact on hydrogen burning, globular clusters, and the age of the universe

    NASA Astrophysics Data System (ADS)

    Runkle, Robert Charles

    2003-10-01

    Stars create the light we observe from energy liberated by nuclear fusion reactions. For most of their lives, stars exist as main-sequence objects quiescently burning hydrogen. At temperatures present in stars slightly larger than the Sun, the CN cycle dominates hydrogen burning and thus a star's macroscopic properties such as luminosity and main sequence turnoff. Because it is the slowest step in the CN cycle, the 14N(p,γ)15O reaction dictates the rate of hydrogen burning. This fact mandates a good understanding of the 14N(p,γ)15O reaction rate. Although this reaction is well understood at high energies, there are large uncertainties at astrophysically relevant energies. We conducted a new measurement of the 14N(p,γ)15O low energy cross section that extends very close to temperatures present in massive stars. The previous uncertainty in the reaction rate resulted from the possible contribution of a subthreshold resonance in the ground state transition. Our measurement suggests that this resonance does not contribute significantly. We conclude that the 6793 keV state in 15O dominates the low energy cross section. Indirect measurements support our extrapolation of this state to very low energies, which results in a factor of two reduction in the reaction rate for temperature below 108 K. This new result has a significant impact on the theory of the evolution of massive stars. It significantly increases the predicted age of the oldest globular clusters and helps provide a better constraint on cosmological parameters that determine the present age of the Universe.

  5. Tannic acid reduces recovery of water-soluble carbon and nitrogen from soil and affects the composition of Bradford-reactive soil protein

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tannins are plant-derived polyphenolic compounds that precipitate proteins, bind to metals and complex with other compounds and may be particularly important in soil ecosystems. Solutions of tannic acid, or other phenolic compounds, were added to soil samples to determine if they would affect recov...

  6. Food web of a confined and anthropogenically affected coastal basin (the Mar Piccolo of Taranto) revealed by carbon and nitrogen stable isotopes analyses.

    PubMed

    Bongiorni, Lucia; Fiorentino, Federica; Auriemma, Rocco; Aubry, Fabrizio Bernardi; Camatti, Elisa; Camin, Federica; Nasi, Federica; Pansera, Marco; Ziller, Luca; Grall, Jacques

    2016-07-01

    Carbon and nitrogen stable isotope analysis was used to examine the food web of the Mar Piccolo of Taranto, a coastal basin experiencing several anthropogenic impacts. Main food sources (algal detritus, seaweeds, particulate organic matter (POM) and sediment organic matter (SOM)) and benthic and pelagic consumers were collected during two contrasting seasons (June and April), at four sites distributed over two inlets, and characterized by different level of confinements, anthropogenic inputs and the presence of mussels farming. δ(13)C values of organic sources revealed an important contribution of POM to both planktonic and benthic pathways, as well as the influence of terrigenous inputs within both inlets, probably due to high seasonal land runoff. Although δ(13)C of both sources and consumers varied little between sampling sites and dates, δ(15)N spatial variability was higher and clearly reflected the organic enrichment in the second inlet as well as the uptake of anthropogenically derived material by benthic consumers. On the other hand, within the first inlet, the isotopic composition of consumers did not change in response to chemical contamination. However, the impact of polluted sediments near the Navy Arsenal in the first inlet was detectable at the level of the macrobenthic trophic structure, showing high dominance of motile, upper level consumers capable to face transient conditions and the reduction of the more resident deposit feeders. We therefore underline the great potential of matching stable isotope analysis with quantitative studies of community structure to assess the effects of multiple anthropogenic stressors. PMID:26381790

  7. Ordered Semiconducting Nitrogen-Graphene Alloys

    SciTech Connect

    Xiang, H. J.; Huang, B.; Li, Z. Y.; Wei, S. H.; Yang, J. L.; Gong, X. G.

    2012-01-01

    The interaction between substitutional nitrogen atoms in graphene is studied by performing first-principles calculations. The effective nearest-neighbor interaction between nitrogen dopants is found to be highly repulsive because of the strong electrostatic repulsion between nitrogen atoms. This interaction prevents the full nitrogen-carbon phase separation in nitrogen-doped graphene. Interestingly, there are two relatively stable nitrogen-nitrogen pair configurations, whose stability can be attributed to the anisotropy in the charge redistribution induced by nitrogen doping. We reveal two stable, ordered, semiconducting N-doped graphene structures, C{sub 3}N and C{sub 12}N, through the cluster-expansion technique and particle-swarm optimization method. In particular, we show that C{sub 12}N has a direct band gap of 0.98 eV. The heterojunctions between C{sub 12}N and graphene nanoribbons might be a promising basis for organic solar cells.

  8. Nitrogen Index

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is a need to improve the management of nitrogen inputs to agricultural systems because they increase the potential for losses of reactive nitrogen to the environment, resulting in negative impacts to water and air resources. There is a need to reduce nitrate leaching, emissions of N2O from agr...

  9. Route of tracer administration does not affect ileal endogenous nitrogen recovery measured with the 15N-isotope dilution technique in pigs fed rapidly digestible diets.

    PubMed

    Steendam, C A Carina; Verstegen, Martin W A; Tamminga, Seerp; Boer, Huug; van 't End, Marianne; Verstappen, Berthe; Caine, William R; Visser, G Henk

    2004-11-01

    The (15)N-isotope dilution technique ((15)N-IDT), with either pulse-dose oral administration or continuous i.v. administration of [(15)N]-l-leucine (carotid artery), both at 5 mg/(kg body weight . d), was used to measure ileal (postvalve T-cecum cannula) endogenous nitrogen recovery (ENR) in pigs (9 +/- 0.6 kg). Diets were cornstarch, enzyme-hydrolyzed casein with no (control) or high (4%) content of quebracho extract (Schinopsis spp.) rich in condensed tannins. Blood was sampled from a catheter in the external jugular vein. Mean plasma (15)N-enrichment at d 8-10 was higher (P = 0.0009) after i.v. than after oral administration [0.0356 vs. 0.0379 atom% excess (APE)]. Plasma (15)N-enrichment for i.v. infused pigs was 0.01117 APE higher (P < 0.0001) and for orally dosed pigs 0.0081 APE lower (P < 0.0001) at 11 h postprandial compared with 1 h postprandial. Apparent ileal N digestibility was higher (P < 0.0001) for the control (85.5%) than for the quebracho diet (69.5%). ENR was calculated from the ratio of (15)N-enrichment of plasma and digesta. The ENR for the quebracho diet was approximately 300% higher than for the control diet (6.03 vs. 1.94 g/kg dry matter intake, P < 0.001). The real N digestibility (92.2 +/- 0.4%) was equal for both diets (P = 0.1030) and both tracer methods (P = 0.9730). We concluded that oral administration of [(15)N]leucine provides reasonable estimates of ENR in pigs fed semipurified diets with high or low content of tannins; however, one must be careful in extrapolating this conclusion to studies with other protein sources or feeding frequencies. PMID:15514277

  10. ELEVATED CO{sub 2} IN A PROTOTYPE FREE-AIR CO{sub 2} ENRICHMENT FACILITY AFFECTS PHOTOSYNTHETIC NITROGEN RELATIONS IN A MATURING PINE FOREST

    SciTech Connect

    ELLSWORTH,D.S.; LA ROCHE,J.; HENDREY,G.R.

    1998-03-01

    A maturing loblolly pine (Pinus taeda L.) forest was exposed to elevated CO{sub 2} in the natural environment in a perturbation study conducted over three seasons using the free-air CO{sub 2} enrichment (FACE) technique. At the time measurements were begun in this study, the pine canopy was comprised entirely of foliage which had developed under elevated CO{sub 2} conditions (atmospheric [CO{sub 2}] {approx} 550 {micro}mol mol{sup {minus}1}). Measurements of leaf photosynthetic responses to CO{sub 2} were taken to examine the effects of elevated CO{sub 2} on photosynthetic N nutrition in a pine canopy under elevated CO{sub 2}. Photosynthetic CO{sub 2} response curves (A-c{sub i} curves) were similar in FACE trees under elevated CO{sub 2} compared with counterpart trees in ambient plots for the first foliage cohort produced in the second season of CO{sub 2} exposure, with changes in curve form detected in the foliage cohorts subsequently produced under elevated CO{sub 2}. Differences in the functional relationship between carboxylation rate and N{sub a} suggest that for a given N{sub a} allocated among successive cohorts of foliage in the upper canopy, V{sub c max} was 17% lower in FACE versus Ambient trees. The authors also found that foliar Rubisco content per unit total protein derived from Western blot analysis was lower in late-season foliage in FACE foliage compared with ambient-grown foliage. The results illustrate a potentially important mode of physiological adjustment to growth conditions that may operate in forest canopies. Their findings suggest that mature loblolly pine trees growing in the field may have the capacity for shifts in intrinsic nitrogen utilization for photosynthesis under elevated CO{sub 2} that are not dependent on changes in leaf N. While carboxylation efficiency per unit N apparently decreased under elevated CO{sub 2}, photosynthetic rates in trees at elevated CO{sub 2} concentrations {approx} 550 pmol mol{sub {minus}1} are still

  11. Elevated CO{sub 2} in a prototype free-air CO{sub 2} enrichment facility affects photosynthetic nitrogen relations in a maturing pine forest

    SciTech Connect

    Ellsworth, D.S.; LaRoche, J.; Hendrey, G.R.

    1998-03-01

    A maturing loblolly pine (Pinus taeda L.) forest was exposed to elevated CO{sub 2} in the natural environment in a perturbation study conducted over three seasons using the free-air CO{sub 2} enrichment (FACE) technique. At the time measurements were begun in this study, the pine canopy was comprised entirely of foliage which had developed under elevated CO{sub 2} conditions (atmospheric CO{sub 2} {approx} 550 {micro}mol/mol{sup {minus}1}). Measurements of leaf photosynthetic responses to CO{sub 2} were taken to examine the effects of elevated CO{sub 2} on photosynthetic N nutrition in a pine canopy under elevated CO{sub 2}. Photosynthetic CO{sub 2} response curves (A-c{sub i} curves) were similar in FACE trees under elevated CO{sub 2} compared with counterpart trees in ambient plots for the first foliage cohort produced in the second season of CO{sub 2} exposure, with changes in curve form detected in the foliage cohorts subsequently produced under elevated CO{sub 2}. Differences in the functional relationship between carboxylation rate and N{sub a} suggest that for a given N{sub a} allocated among successive cohorts of foliage in the upper canopy, V{sub c max} was 17% lower in FACE versus Ambient trees. The authors also found that foliar Rubisco content per unit total protein derived from Western blot analysis was lower in late-season foliage in FACE foliage compared with ambient-grown foliage. The results illustrate a potentially important mode of physiological adjustment to growth conditions that may operate in forest canopies. Findings suggest that mature loblolly pine trees growing in the field may have the capacity for shifts in intrinsic nitrogen utilization for photosynthesis under elevated CO{sub 2} that are not dependent on changes in leaf N. Findings suggest a need for continued examination of internal feedbacks at the whole-tree and ecosystem level in forests that may influence long-term photosynthetic responses to elevated CO{sub 2}.

  12. Nitrogen quantification with SNMS

    NASA Astrophysics Data System (ADS)

    Goschnick, J.; Natzeck, C.; Sommer, M.

    1999-04-01

    Plasma-based secondary neutral mass spectrometry (plasma SNMS) is a powerful analytical method for determining the elemental concentrations of almost any kind of material at low cost by using a cheap quadrupole mass filter. However, a quadrupole-based mass spectrometer is limited to nominal mass resolution. Atomic signals are sometimes superimposed by molecular signals (2 or 3 atomic clusters such as CH +, CH 2+ or metal oxide clusters) and/or intensities of double-charged species. Especially in the case of nitrogen several interferences can impede the quantification. This article reports on methods to recognize and deconvolute superpositions of N + with CH 2+, Li 2+, and Si 2+ at mass 14 D (Debye) occurring during analysis of organic and inorganic substances. The recognition is based on the signal pattern of N +, Li +, CH +, and Si +. The latter serve as indicators for a probable interference of molecular or double-charged species with N on mass 14 D. The subsequent deconvolution use different shapes of atomic and cluster kinetic energy distributions (kEDs) to determine the quantities of the intensity components by a linear fit of N + and non-atomic kEDs obtained from several organic and inorganic standards into the measured kED. The atomic intensity fraction yields a much better nitrogen concentration than the total intensity of mass 14 D after correction.

  13. Processing of soybean meal and 00-rapeseed meal reduces protein digestibility and pig growth performance but does not affect nitrogen solubilization along the small intestine.

    PubMed

    Hulshof, T G; van der Poel, A F B; Hendriks, W H; Bikker, P

    2016-06-01

    An experiment was conducted to determine the effects of processing of soybean meal (SBM) and 00-rapeseed meal (RSM) on N solubilization in chyme, CP digestibility along the small intestine, metabolic load as determined by organ weight, body composition, and growth performance in growing pigs. The SBM and RSM were processed by secondary toasting (at 95°C for 30 min) in the presence of lignosulfonate, resulting in processed SBM (pSBM) and processed RSM (pRSM) as a model for overprocessed protein sources. Fifty-four growing pigs were each fed 1 of the 6 experimental diets. Four of the diets contained SBM, pSBM, RSM, or pRSM as the sole protein source. The remaining 2 experimental diets contained pSBM or pRSM and were supplemented with crystalline AA to the same standardized ileal digestible AA levels as the SBM or RSM diet. Pigs were slaughtered at 40 kg, and organ weights were recorded. The organs plus blood and empty carcass were analyzed for CP content. The small intestine was divided into 3 segments, and chyme samples were taken from the last meter of each segment. Chyme of the SBM, pSBM, RSM, and pRSM diets was centrifuged to separate the soluble and insoluble fractions, and N content was determined in the latter. The amount of insoluble N as a fraction of N in chyme at each small intestinal segment was not affected by processing. Diet type, comprising effects of processing and supplementing crystalline AA, affected ( < 0.05) the G:F and standardized ileal digestibility (SID) of CP. Processing reduced G:F from 0.56 to 0.38 for SBM and 0.49 to 0.40 for RSM, whereas supplementing crystalline AA increased G:F to the level of the SBM and RSM diets. Processing reduced the SID of CP from 87.2% to 69.2% for SBM and 71.0% to 52.2% for RSM. Diet type affected ( < 0.05) the CP content in the empty body, with processing reducing this content from 170 to 144 g/kg empty BW for SBM and 157 to 149 g/kg empty BW for RSM and supplementing crystalline AA restoring this content

  14. Nitrogen Uptake in Spinach

    NASA Astrophysics Data System (ADS)

    Ramirez, J.; VanBenthem, P.

    2013-12-01

    A plant's absorption of nitrogen can be encouraged by a variety of environmental factors, especially the application of fertilizers. As a common limiting factor in plant growth, not up taking enough nitrogen can be a result of an unhealthy plant. Moreover, as farmers seek out methods to increase growth of plants, fertilizers are used as a solution to the issue of nitrogen deficiency to incorporate additional nitrogen from chemical or organic sources, by not using the right fertilizer can greatly affect the plats. The point of this research project is to determine the effect of various fertilizers on the plant growth, and to correlate the measured nitrogen, water and chlorophyll content in spinach leaves. Spinach leaves were used because they are known to quickly uptake chemicals in the environment. The spinach plants were exposed to four different growing parameters, which are referred to as control, ammonium nitrate, MiracleGro , and organic. The spinach was originally placed in nitrogen deficient soil with only 2.2x10 4 weight percent (wt. %) nitrogen. The leaves in the control group were grown in this nitrogen deficient soil without any fertilizer added. Ammomium nitrate and MiracleGro were added to the spinach in the A and MG groups, respectively, and organic chicken stool was used for the O group. By using a spectral imaging system and flame combustion techniques, the chlorophyll content can be related to the nitrogen content in the spinach leaves. In these spinach leaves, nitrogen and chlorophyll content were measured, chlorophyll is a green pigment that plays a crucial role in producing nutrients for green plants. The lack of chlorophyll will allow the plant to become susceptible to diseases, so it is extremely important that the plants have a high content of chlorophyll. The role of nitrogen in chlorophyll is very important and helps in the creation of chlorophyll; therefore it is necessary that an appropriate amount of nitrogen is added for optimal growth

  15. Cluster ion beam profiling of organics by secondary ion mass spectrometry--does sodium affect the molecular ion intensity at interfaces?

    PubMed

    Green, Felicia M; Gilmore, Ian S; Seah, Martin P

    2008-12-01

    The use of cluster ion beam sputtering for depth profiling organic materials is of growing technological importance and is a very active area of research. At the 44th IUVSTA Workshop on "Sputtering and Ion Emission by Cluster Ion Beams", recent results were presented of a cluster ion beam depth profile of a thin organic molecular layer on a silicon wafer substrate. Those data showed that the intensity of molecular secondary ions is observed to increase at the interface and this was explained in terms of the higher stopping power in the substrate and a consequently higher sputtering yield and even higher secondary ion molecular sputtering yield. An alternative hypothesis was postulated in the workshop discussion which may be paraphrased as: "under primary ion bombardment of an organic layer, mobile ions such as sodium may migrate to the interface with the inorganic substrate and this enhancement of the sodium concentration increases the ionisation probability, so increasing the molecular ion yield observed at the interface". It is important to understand if measurement artefacts occur at interfaces for quantification as these are of great technological relevance - for example, the concentration of drug in a drug delivery system. Here, we evaluate the above hypothesis using a sample that exhibits regions of high and low sodium concentration at both the organic surface and the interface with the silicon wafer substrate. There is no evidence to support the hypothesis that the probability of molecular secondary ion ionisation is related to the sodium concentration at these levels. PMID:19039819

  16. Haplotypes in the APOA1-C3-A4-A5 gene cluster affect plasma lipids in both humans and baboons

    SciTech Connect

    Wang, Qian-fei; Liu, Xin; O'Connell, Jeff; Peng, Ze; Krauss, Ronald M.; Rainwater, David L.; VandeBerg, John L.; Rubin, Edward M.; Cheng, Jan-Fang; Pennacchio, Len A.

    2003-09-15

    Genetic studies in non-human primates serve as a potential strategy for identifying genomic intervals where polymorphisms impact upon human disease-related phenotypes. It remains unclear, however, whether independently arising polymorphisms in orthologous regions of non-human primates leads to similar variation in a quantitative trait found in both species. To explore this paradigm, we studied a baboon apolipoprotein gene cluster (APOA1/C3/A4/A5) for which the human gene orthologs have well established roles in influencing plasma HDL-cholesterol and triglyceride concentrations. Our extensive polymorphism analysis of this 68 kb gene cluster in 96 pedigreed baboons identified several haplotype blocks each with limited diversity, consistent with haplotype findings in humans. To determine whether baboons, like humans, also have particular haplotypes associated with lipid phenotypes, we genotyped 634 well characterized baboons using 16 haplotype tagging SNPs. Genetic analysis of single SNPs, as well as haplotypes, revealed an association of APOA5 and APOC3 variants with HDL cholesterol and triglyceride concentrations, respectively. Thus, independent variation in orthologous genomic intervals does associate with similar quantitative lipid traits in both species, supporting the possibility of uncovering human QTL genes in a highly controlled non-human primate model.

  17. Nitrogen species

    NASA Astrophysics Data System (ADS)

    Harries, J. E.; Brasseur, G.; Coffey, M. T.; Fischer, H.; Gille, J.; Jones, R.; Louisnard, N.; McCormick, M. P.; Noxon, J.; Owens, A. J.

    Total odd nitrogen, NO(y), may be defined as the sum of all active nitrogen species that interchange photochemically with one another on a time scale of the order of weeks or less. As noted, NO + NO2 reactions dominate the processes controlling the ozone balance in the contemporary stratosphere. The observational data from non-satellite platforms are reviewed. The growth in available satellite data in the past four years is considered. Some of the most important scientific issues are discussed, taking into account new results from atmospheric models (mainly 2-D). The model results are compared with the observational data.

  18. Nitrogen species

    NASA Technical Reports Server (NTRS)

    Harries, J. E.; Brasseur, G.; Coffey, M. T.; Fischer, H.; Gille, J.; Jones, R.; Louisnard, N.; Mccormick, M. P.; Noxon, J.; Owens, A. J.

    1985-01-01

    Total odd nitrogen, NO(y), may be defined as the sum of all active nitrogen species that interchange photochemically with one another on a time scale of the order of weeks or less. As noted, NO + NO2 reactions dominate the processes controlling the ozone balance in the contemporary stratosphere. The observational data from non-satellite platforms are reviewed. The growth in available satellite data in the past four years is considered. Some of the most important scientific issues are discussed, taking into account new results from atmospheric models (mainly 2-D). The model results are compared with the observational data.

  19. CLUSTER CHEMISTRY

    SciTech Connect

    Muetterties, Earl L.

    1980-05-01

    Metal cluster chemistry is one of the most rapidly developing areas of inorganic and organometallic chemistry. Prior to 1960 only a few metal clusters were well characterized. However, shortly after the early development of boron cluster chemistry, the field of metal cluster chemistry began to grow at a very rapid rate and a structural and a qualitative theoretical understanding of clusters came quickly. Analyzed here is the chemistry and the general significance of clusters with particular emphasis on the cluster research within my group. The importance of coordinately unsaturated, very reactive metal clusters is the major subject of discussion.

  20. Interaction of air temperature and nitrogen supply on root growth and nitrogen uptake by corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nutrient uptake rates by plants are governed by both plant processes and soil properties. Simulation models of nitrogen uptake should account for both demand and availability of nitrogen. The goal of this study was to quantify root growth and nitrogen uptake by corn plants (maize) as affected by air...

  1. Nitrogen dioxide

    Integrated Risk Information System (IRIS)

    Nitrogen dioxide ; CASRN 10102 - 44 - 0 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogeni

  2. Nitrogen Starvation and TorC1 Inhibition Differentially Affect Nuclear Localization of the Gln3 and Gat1 Transcription Factors Through the Rare Glutamine tRNACUG in Saccharomyces cerevisiae

    PubMed Central

    Tate, Jennifer J.; Rai, Rajendra; Cooper, Terrance G.

    2015-01-01

    A leucine, leucyl-tRNA synthetase–dependent pathway activates TorC1 kinase and its downstream stimulation of protein synthesis, a major nitrogen consumer. We previously demonstrated, however, that control of Gln3, a transcription activator of catabolic genes whose products generate the nitrogenous precursors for protein synthesis, is not subject to leucine-dependent TorC1 activation. This led us to conclude that excess nitrogen-dependent down-regulation of Gln3 occurs via a second mechanism that is independent of leucine-dependent TorC1 activation. A major site of Gln3 and Gat1 (another GATA-binding transcription activator) control occurs at their access to the nucleus. In excess nitrogen, Gln3 and Gat1 are sequestered in the cytoplasm in a Ure2-dependent manner. They become nuclear and activate transcription when nitrogen becomes limiting. Long-term nitrogen starvation and treatment of cells with the glutamine synthetase inhibitor methionine sulfoximine (Msx) also elicit nuclear Gln3 localization. The sensitivity of Gln3 localization to glutamine and inhibition of glutamine synthesis prompted us to investigate the effects of a glutamine tRNA mutation (sup70-65) on nitrogen-responsive control of Gln3 and Gat1. We found that nuclear Gln3 localization elicited by short- and long-term nitrogen starvation; growth in a poor, derepressive medium; Msx or rapamycin treatment; or ure2Δ mutation is abolished in a sup70-65 mutant. However, nuclear Gat1 localization, which also exhibits a glutamine tRNACUG requirement for its response to short-term nitrogen starvation or growth in proline medium or a ure2Δ mutation, does not require tRNACUG for its response to rapamycin. Also, in contrast with Gln3, Gat1 localization does not respond to long-term nitrogen starvation. These observations demonstrate the existence of a specific nitrogen-responsive component participating in the control of Gln3 and Gat1 localization and their downstream production of nitrogenous precursors

  3. Nitrogen starvation and TorC1 inhibition differentially affect nuclear localization of the Gln3 and Gat1 transcription factors through the rare glutamine tRNACUG in Saccharomyces cerevisiae.

    PubMed

    Tate, Jennifer J; Rai, Rajendra; Cooper, Terrance G

    2015-02-01

    A leucine, leucyl-tRNA synthetase-dependent pathway activates TorC1 kinase and its downstream stimulation of protein synthesis, a major nitrogen consumer. We previously demonstrated, however, that control of Gln3, a transcription activator of catabolic genes whose products generate the nitrogenous precursors for protein synthesis, is not subject to leucine-dependent TorC1 activation. This led us to conclude that excess nitrogen-dependent down-regulation of Gln3 occurs via a second mechanism that is independent of leucine-dependent TorC1 activation. A major site of Gln3 and Gat1 (another GATA-binding transcription activator) control occurs at their access to the nucleus. In excess nitrogen, Gln3 and Gat1 are sequestered in the cytoplasm in a Ure2-dependent manner. They become nuclear and activate transcription when nitrogen becomes limiting. Long-term nitrogen starvation and treatment of cells with the glutamine synthetase inhibitor methionine sulfoximine (Msx) also elicit nuclear Gln3 localization. The sensitivity of Gln3 localization to glutamine and inhibition of glutamine synthesis prompted us to investigate the effects of a glutamine tRNA mutation (sup70-65) on nitrogen-responsive control of Gln3 and Gat1. We found that nuclear Gln3 localization elicited by short- and long-term nitrogen starvation; growth in a poor, derepressive medium; Msx or rapamycin treatment; or ure2Δ mutation is abolished in a sup70-65 mutant. However, nuclear Gat1 localization, which also exhibits a glutamine tRNACUG requirement for its response to short-term nitrogen starvation or growth in proline medium or a ure2Δ mutation, does not require tRNACUG for its response to rapamycin. Also, in contrast with Gln3, Gat1 localization does not respond to long-term nitrogen starvation. These observations demonstrate the existence of a specific nitrogen-responsive component participating in the control of Gln3 and Gat1 localization and their downstream production of nitrogenous precursors. This

  4. Nitrogen Mineralization Response to Tillage Practices on Low and High Nitrogen Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In strip tillage, crop residue is left on soil surface, decreasing the contact between soil and the residue, and therefore reducing decomposition rates compared to conventional tillage methods. Decomposition rates directly affect carbon and nitrogen ratios, which can affect nitrogen mineralization r...

  5. Modeling Clustered Data with Very Few Clusters.

    PubMed

    McNeish, Daniel; Stapleton, Laura M

    2016-01-01

    Small-sample inference with clustered data has received increased attention recently in the methodological literature, with several simulation studies being presented on the small-sample behavior of many methods. However, nearly all previous studies focus on a single class of methods (e.g., only multilevel models, only corrections to sandwich estimators), and the differential performance of various methods that can be implemented to accommodate clustered data with very few clusters is largely unknown, potentially due to the rigid disciplinary preferences. Furthermore, a majority of these studies focus on scenarios with 15 or more clusters and feature unrealistically simple data-generation models with very few predictors. This article, motivated by an applied educational psychology cluster randomized trial, presents a simulation study that simultaneously addresses the extreme small sample and differential performance (estimation bias, Type I error rates, and relative power) of 12 methods to account for clustered data with a model that features a more realistic number of predictors. The motivating data are then modeled with each method, and results are compared. Results show that generalized estimating equations perform poorly; the choice of Bayesian prior distributions affects performance; and fixed effect models perform quite well. Limitations and implications for applications are also discussed. PMID:27269278

  6. Electronic structure calculations of group III nitride clusters

    NASA Astrophysics Data System (ADS)

    Kandalam, Anil Kumar

    2002-04-01

    Group III nitrides have become materials of choice in the manufacturing of devices used in opto-electronic and high-temperature high-power electronic industries. Hence, these materials received wide attention and have become the focus of several theoretical and experimental studies. Though these materials are studied in bulk and thin film forms, research at the cluster level is still lacking. Hence, a first principles calculation, based on the Generalized Gradient Approximation (GGA) to Density Functional Theory (DFT) was initiated to study the structural and electronic properties of AlnN n, GanNn, and InnNn, (n = 1--6) clusters. The calculated results show that the small polyatomic nitride clusters (monomer, triatomic and dimer) have a strong tendency to form N-N multiple bonds leading to the weakening of any existent metal-N or metal-metal bonds. In the absence of the N-N bonds, the metal-nitrogen bond dominates, forming short bond-lengths and large force constants. However, the strength of these heteronuclear bonds decreases in going from Al to Ga and In, whereas the weak metal-metal bond increases its strength from Al to Ga to In in the nitride clusters. Starting from the trimers M3N3, a distinct structural difference between the lowest energy configurations of AlnNn and that of GanNn, and In nNn, clusters has been observed. For AlnNn, clusters, the metal-nitrogen bond is found to dominate the lowest energy configurations. As the cluster size is increased from Al3N3 to Al 6N6, a transition from planar ring structures towards a bulk-like three dimensional configurations is seen. However, in GanN n, and InnNn clusters, no such trend is observed and the lowest energy configurations are dominated either by N2 or (N3)- sub-units. The segregation of N atoms within the stoichiometric clusters indicates the possibility of N2 and N3 based defects in the thin-film deposition process which may affect the quality of the thin-film devices based on Group III nitrides.

  7. Meaningful Clusters

    SciTech Connect

    Sanfilippo, Antonio P.; Calapristi, Augustin J.; Crow, Vernon L.; Hetzler, Elizabeth G.; Turner, Alan E.

    2004-05-26

    We present an approach to the disambiguation of cluster labels that capitalizes on the notion of semantic similarity to assign WordNet senses to cluster labels. The approach provides interesting insights on how document clustering can provide the basis for developing a novel approach to word sense disambiguation.

  8. Regulation of genes involved in nitrogen utilization on different C/N ratios and nitrogen sources in the model ectomycorrhizal fungus Hebeloma cylindrosporum.

    PubMed

    Avolio, Meghan; Müller, Tobias; Mpangara, Anja; Fitz, Michael; Becker, Ben; Pauck, Alexander; Kirsch, Anja; Wipf, Daniel

    2012-10-01

    Nitrogen (N) utilization by ectomycorrhizal fungi is an essential aspect of their ecosystem function. N deposition changes both the N pools and the carbon/nitrogen (C/N) ratio of the substrates where ectomycorrhizal fungi are found, and it is important to understand how these changes affect the N forms used by ectomycorrhizal fungi. To overcome the difficulties of studying ectomycorrhizal fungi in situ, we investigated all known N genes in the model fungus, Hebeloma cylindrosporum in a culture study. In addition to studying the regulation of all known N utilization genes, we aimed to understand whether there are gene clusters that undergo similar regulation. Lastly we studied how C/N ratio, N transporter type, and N source affected relative gene expression levels. We grew the D2 strain of H. cylindrosporum on a range of inorganic and organic N sources under low, medium, and high C/N ratios. We found three gene clusters that were regulated in a similar pattern. Lastly, we found C/N ratio, N source and N transporter type all affected gene expression levels. Relative expression levels were highest on the high C/N ratio, BSA and diLeucine N sources, and inorganic N transporters were always expressed at higher levels than organic N transporters. These results suggest that inorganic N sources may always the default preference for H. cylindrosporum, regardless of both the N sources and the C/N ratio of the substrate. PMID:22302131

  9. Effects of Nitrogen Fertilization on Tritrophic Interactions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant—herbivore—natural enemy interactions are basic components of nearly all ecosystems, and nitrogen can exert a variety of effects on plants which can significantly alter these interactions. We present a diagram illustrating the various ways that nitrogen can affect three trophic levels and revi...

  10. Interactive effects of nitrogen deposition and insect herbivory on carbon and nitrogen dynamics: Results from CENTURY

    NASA Astrophysics Data System (ADS)

    Throop, H. L.; Holland, E. A.; Parton, W. J.; Ojima, D. S.; Keough, C.

    2002-12-01

    The direct effects of nitrogen deposition on nutrient availability in ecosystems have been well studied, however, little is known about the indirect effects of nitrogen deposition on insect herbivory and subsequent changes to ecosystem processes. Numerous empirical studies have demonstrated that host plant nitrogen concentration can strongly affect individual insect consumption rates and population dynamics. We used the CENTURY ecosystem model to explore how interactions between nitrogen deposition and insect herbivory might affect plant production and the pools and fluxes of carbon and nitrogen in an old field community. We modified the preexisting CENTURY mammalian grazing functions to reflect patterns of insect herbivory. Vegetative tissue loss to herbivores was modeled as a dynamic function based on the carbon to nitrogen ratio of aboveground vegetation. Parameterization of the plant response to nitrogen and herbivory was based on field data collected on Ambrosia artemisiifolia (common ragweed, Asteraceae). The modeled response to nitrogen deposition included a strong increase in plant production, decreased plant C:N ratios, and increased soil organic carbon pools. Insect herbivory alone generally caused depressed aboveground production, decreased soil organic carbon pools, and decreased nitrogen mineralization rates. These relationships broke down, however, under moderate nitrogen deposition loads (over 30 kg N ha-1 yr-1) in simulations where insect herbivory increased in response to declining plant C:N. In these cases, herbivory acted to depress the positive influence of nitrogen deposition on carbon storage in soil and vegetative pools and caused strong increases in nitrogen mineralization rates. The results of these simulations suggest that herbivory may play an increasingly important role in affecting ecosystem processes under conditions of high nitrogen deposition. Including effects of herbivory in ecosystem analyses, particularly in systems where rates