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  • 1
    Language: German
    In: Medizinrecht, 2015, Vol.33(5), pp.384-384
    Keywords: Law ; Medical Law ; Medicine/Public Health, General ; Law ; Public Health;
    ISSN: 0723-8886
    E-ISSN: 1433-8629
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  • 2
    Language: English
    In: Geochimica et Cosmochimica Acta, Jan 15, 2014, Vol.125, p.519(9)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.gca.2013.10.010 Byline: Christian von Sperber, Hajo Kries, Federica Tamburini, Stefano M. Bernasconi, Emmanuel Frossard Abstract: Plants and microorganisms under phosphorus (P) stress release extracellular phosphatases as a strategy to acquire inorganic phosphate (P.sub.i). These enzymes catalyze the hydrolysis of phosphoesters leading to a release of P.sub.i. During the enzymatic hydrolysis an isotopic fractionation (I[micro]) occurs leaving an imprint on the oxygen isotope composition of the released P.sub.i which might be used to trace phosphorus in the environment. Therefore, enzymatic assays with acid phosphatases from wheat germ and potato tuber and alkaline phosphatase from Escherichia coli were prepared in order to determine the oxygen isotope fractionation caused by these enzymes. Adenosine 5' monophosphate and glycerol phosphate were used as substrates. The oxygen isotope fractionation caused by acid phosphatases is 20-30a[degrees] smaller than for alkaline phosphatases, resulting in a difference of 5-7.5a[degrees] in [delta].sup.18O of P.sub.i depending on the enzyme. We attribute the enzyme dependence of the isotopic fractionation to distinct reaction mechanisms of the two types of phosphatases. The observed difference is large enough to distinguish between the two enzymatic processes in environmental samples. These findings show that the oxygen isotope composition of P.sub.i can be used to trace different enzymatic processes, offering an analytical tool that might contribute to a better understanding of the P-cycle in the environment. Article History: Received 2 May 2013; Accepted 6 October 2013 Article Note: (miscellaneous) Associate editor: Jon Chorover
    Keywords: Adenosine ; Glycerol ; Enzymes ; Phosphates ; Enzymology ; Hydrolysis
    ISSN: 0016-7037
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Geochimica et Cosmochimica Acta, 15 January 2014, Vol.125, pp.519-527
    Description: Plants and microorganisms under phosphorus (P) stress release extracellular phosphatases as a strategy to acquire inorganic phosphate (P ). These enzymes catalyze the hydrolysis of phosphoesters leading to a release of P . During the enzymatic hydrolysis an isotopic fractionation (ε) occurs leaving an imprint on the oxygen isotope composition of the released P which might be used to trace phosphorus in the environment. Therefore, enzymatic assays with acid phosphatases from wheat germ and potato tuber and alkaline phosphatase from were prepared in order to determine the oxygen isotope fractionation caused by these enzymes. Adenosine 5′ monophosphate and glycerol phosphate were used as substrates. The oxygen isotope fractionation caused by acid phosphatases is 20–30‰ smaller than for alkaline phosphatases, resulting in a difference of 5–7.5‰ in δ O of P depending on the enzyme. We attribute the enzyme dependence of the isotopic fractionation to distinct reaction mechanisms of the two types of phosphatases. The observed difference is large enough to distinguish between the two enzymatic processes in environmental samples. These findings show that the oxygen isotope composition of P can be used to trace different enzymatic processes, offering an analytical tool that might contribute to a better understanding of the P-cycle in the environment.
    Keywords: Geology
    ISSN: 0016-7037
    E-ISSN: 1872-9533
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  • 4
    In: Ecology, April 2017, Vol.98(4), pp.1117-1129
    Description: The supply of nitrogen (N) constrains primary productivity in many ecosystems, raising the question “what controls the availability and cycling of N”? As a step toward answering this question, we evaluated N cycling processes and aspects of their regulation on a climate gradient on Kohala Volcano, Hawaii, USA. The gradient extends from sites receiving 3,000 mm/yr, and the pedology and dynamics of rock‐derived nutrients in soils on the gradient are well understood. In particular, there is a soil process domain at intermediate rainfall within which ongoing weathering and biological uplift have enriched total and available pools of rock‐derived nutrients substantially; sites at higher rainfall than this domain are acid and infertile as a consequence of depletion of rock‐derived nutrients, while sites at lower rainfall are unproductive and subject to wind erosion. We found elevated rates of potential net N mineralization in the domain where rock‐derived nutrients are enriched. Higher‐rainfall sites have low rates of potential net N mineralization and high rates of microbial N immobilization, despite relatively high rates of gross N mineralization. Lower‐rainfall sites have moderately low potential net N mineralization, relatively low rates of gross N mineralization, and rates of microbial N immobilization sufficient to sequester almost all the mineral N produced. Bulk soil δN also varied along the gradient, from +4‰ at high rainfall sites to +14‰ at low rainfall sites, indicating differences in the sources and dynamics of soil N. Our analysis shows that there is a strong association between N cycling and soil process domains that are defined using soil characteristics independent of N along this gradient, and that short‐term controls of N cycling can be understood in terms of the supply of and demand for N.
    Keywords: Climate Gradient ; Δ 15 N ; Hawaii ; Isotope Dilution ; Nitrogen Availability ; Nitrogen Cycling ; Nitrogen Mineralization ; Soil Fertility
    ISSN: 0012-9658
    E-ISSN: 1939-9170
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  • 5
    Language: English
    In: Soil Science Society of America Journal, Jan-Feb, 2014, Vol.78(1), p.38(9)
    Description: Phosphorus is a major nutrient for all living organisms. In the terrestrial environment, P is considered a double-edged sword. In some areas, agricultural production is strongly limited by the low soil P availability, while in others, P inputs in excess of plant needs have resulted in pollution of water bodies. A better understanding of soil-plant P cycling is needed to provide agricultural and environmental managers with better concepts for P use. Together with the routine analysis of soil available P, the determination of P chemical forms, and the use of P radioisotopes, researchers have recently started using the ratio of stable oxygen isotopes in phosphate (?18O-P). The scientific community interested in using this isotopic tracer is slowly but steadily expanding because ?18O-P has proven to provide important information on biological processes influencing the P cycle and it could be used to trace the origin and fate of P in soil-plant systems. This review examines the published results and compiles the available data relevant for soiluplant systems, pinpoints gaps in analytical techniques and knowledge, and suggests key questions and topics to be investigated
    Keywords: Phosphorus (Chemical element) -- Research ; Phosphorus (Chemical element) -- Usage ; Phosphorus (Chemical element) -- Environmental Aspects ; Isotopes -- Research ; Soil Research
    ISSN: 0361-5995
    E-ISSN: 14350661
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  • 6
    Language: English
    In: Journal of Raman Spectroscopy, 2016
    ISSN: Journal of Raman Spectroscopy
    E-ISSN: 03770486
    Source: Wiley (via CrossRef)
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  • 7
    Language: English
    In: Nature Communications, 01 August 2018, Vol.9(1), pp.1-9
    Description: Our understanding of phosphorus (P) cycling in soils, a basis for many ecosystem services, has been limited by the complexity of P forms and processes. Here the authors use spectroscopic and isotopic techniques to estimate turnover times of P pools and tease apart biologically-driven and geochemically-driven...
    Keywords: Biology
    E-ISSN: 2041-1723
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  • 8
    In: FEMS Microbiology Ecology, 2017, Vol. 93(5)
    Description: Changes in species richness along climatological gradients have been instrumental in developing theories about the general drivers of biodiversity. Previous studies on microbial communities along climate gradients on mountainsides have revealed positive, negative and neutral richness trends. We examined changes in richness and composition of Fungi, Bacteria and Archaea in soil along a 50–1000 m elevation, 280–3280 mm/yr precipitation gradient in Hawai’i. Soil properties and their drivers are exceptionally well understood along this gradient. All three microbial groups responded strongly to the gradient, with community ordinations being similar along axes of environmental conditions (pH, rainfall) and resource availability (nitrogen, phosphorus). However, the form of the richness–climate relationship varied between Fungi (positive linear), Bacteria (unimodal) and Archaea (negative linear). These differences were related to resource-ecology and limiting conditions for each group, with fungal richness increasing most strongly with soil carbon, ammonia-oxidizing Archaea increasing with nitrogen mineralization rate, and Bacteria increasing with both carbon and pH. Reponses to the gradient became increasingly variable at finer taxonomic scales and within any taxonomic group most individual OTUs occurred in narrow climate–elevation ranges. These results show that microbial responses to climate gradients are heterogeneous due to complexity of underlying environmental changes and the diverse ecologies of microbial taxa. Fungi, bacteria and archaea all responded strongly to a tropical climate gradient.
    Keywords: Biogeochemistry ; Climate Change ; Elevation ; Diversity Productivity ; Hawai'I ; Ph ; Soil Climosequence
    E-ISSN: 1574-6941
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  • 9
    In: The ISME Journal, 2019, Vol.13(2), p.290-300
    Description: Differentiating the contributions of photosynthesis and respiration to the global carbon cycle is critical for improving predictive climate models. Carbonic anhydrase (CA) activity in leaves is responsible for the largest biosphere-atmosphere trace gas fluxes of carbonyl sulfide (COS) and the oxygen-18 isotopologue of carbon dioxide (CO 18 O) that both reflect gross photosynthetic rates. However, CA activity also occurs in soils and will be a source of uncertainty in the use of COS and CO 18 O as carbon cycle tracers until process-based constraints are improved. In this study, we measured COS and CO 18 O exchange rates and estimated the corresponding CA activity in soils from a range of biomes and land use types. Soil CA activity was not uniform for COS and CO 2 , and patterns of divergence were related to microbial community composition and CA gene expression patterns. In some cases, the same microbial taxa and CA classes catalyzed both COS and CO 2 reactions in soil, but in other cases the specificity towards the two substrates differed markedly. CA activity for COS was related to fungal taxa and β-D-CA expression, whereas CA activity for CO 2 was related to algal and bacterial taxa and α-CA expression. This study integrates gas exchange measurements, enzyme activity models, and characterization of soil taxonomic and genetic diversity to build connections between CA activity and the soil microbiome. Importantly, our results identify kinetic parameters to represent soil CA activity during application of COS and CO 18 O as carbon cycle tracers.
    Keywords: Article ; Biogeochemistry ; Metagenomics ; Microbial Ecology
    ISSN: 1751-7362
    E-ISSN: 1751-7370
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  • 10
    Language: English
    In: 한국토양비료학회 학술발표회 초록집, 2014, Vol.2014(6), pp.482-482
    Keywords: Phosphorus ; Oxygen 18 ; Biological Processes
    Source: DBpia - 디비피아 (Nurimedia)
    Source: DBpia (Nurimedia)
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