Carbon Sinks
Mostrando 13-24 de 25 artigos, teses e dissertações.
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13. Localized Molecular Orbital Description of Nitrogen Lone Pairs
The Boys localization procedure is applied to several molecules possessing nitrogen lone pairs. The Boys structures show a tendency for the N lone pairs to participate in bonding to nearby electron sinks. For example, the Boys structure for planar formamide has two equivalent τ-bond orbitals between the carbonyl carbon and nitrogen atoms. The change in this
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14. Differential Expression of Two Distinct Phenylalanine Ammonia-Lyase Genes in Condensed Tannin-Accumulating and Lignifying Cells of Quaking Aspen
Lignins, along with condensed tannins (CTs) and salicylate-derived phenolic glycosides, constitute potentially large phenylpropanoid carbon sinks in tissues of quaking aspen (Populus tremuloides Michx.). Metabolic commitment to each of these sinks varies during development and adaptation, and depends on l-phenylalanine ammonia-lyase (PAL), an enzyme catalyzi
American Society of Plant Physiologists.
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15. δ-Tonoplast intrinsic protein defines unique plant vacuole functions
Plant cell vacuoles may have either storage or degradative functions. Vegetative storage proteins (VSPs) are synthesized in response to wounding and to developmental switches that affect carbon and nitrogen sinks. Here we show that VSPs are stored in a unique type of vacuole that is derived from degradative central vacuoles coincident with insertion of a new
The National Academy of Sciences.
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16. Feedback control of the rate of peat formation.
The role of peatlands in the global carbon cycle is confounded by two inconsistencies. First, peatlands have been a large reservoir for carbon sequestered in the past, but may be either net sources or net sinks at present. Second, long-term rates of peat accumulation (and hence carbon sequestration) are surprisingly steady, despite great variability in the s
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17. Potential responses of soil organic carbon to global environmental change
Recent improvements in our understanding of the dynamics of soil carbon have shown that 20–40% of the approximately 1,500 Pg of C stored as organic matter in the upper meter of soils has turnover times of centuries or less. This fast-cycling organic matter is largely comprised of undecomposed plant material and hydrolyzable components associated with
The National Academy of Sciences of the USA.
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18. Effect of Rapid Changes in Sink-Source Ratio on Export and Distribution of Products of Photosynthesis in Leaves of Beta vulgaris L. and Phaseolus vulgaris L. 1
Effects of increasing sink-source ratio on rate of translocation and net carbon exchange were studied by darkening all but one source leaf of Beta vulgaris L. or one primary leaf of Phaseolus vulgaris L. Rates of export of labeled material and patterns of its distribution among sinks were studied by means of GM detectors. Changes in export and import rates w
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19. The Penalty of a Long, Hot Summer. Photosynthetic Acclimation to High CO2 and Continuous Light in “Living Fossil” Conifers1
Deciduous forests covered the ice-free polar regions 280 to 40 million years ago under warm “greenhouse” climates and high atmospheric pCO2. Their deciduous habit is frequently interpreted as an adaptation for minimizing carbon losses during winter, but experiments with “living fossils” in a simulated warm polar environment refute this explanation. M
The American Society for Plant Biologists.
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20. Modulation of Acetone-Butanol-Ethanol Fermentation by Carbon Monoxide and Organic Acids
Metabolic modulation of acetone-butanol-ethanol fermentation by Clostridium acetobutylicum with carbon monoxide (CO) and organic acids is described. CO, which is a known inhibitor of hydrogenase, was found to be effective in the concentration range of dissolved CO corresponding to a CO partial pressure of 0.1 to 0.2 atm. Metabolic modulation by CO was partic
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21. Taurine reduction in anaerobic respiration of Bilophila wadsworthia RZATAU.
Organosulfonates are important natural and man-made compounds, but until recently (T. J. Lie, T. Pitta, E. R. Leadbetter, W. Godchaux III, and J. R. Leadbetter. Arch. Microbiol. 166:204-210, 1996), they were not believed to be dissimilated under anoxic conditions. We also chose to test whether alkane- and arenesulfonates could serve as electron sinks in resp
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22. Does Free-Air Carbon Dioxide Enrichment Affect Photochemical Energy Use by Evergreen Trees in Different Seasons? A Chlorophyll Fluorescence Study of Mature Loblolly Pine1
Previous studies of the effects of growth at elevated CO2 on energy partitioning in the photosynthetic apparatus have produced conflicting results. The hypothesis was developed and tested that elevated CO2 increases photochemical energy use when there is a high demand for assimilates and decreases usage when demand is low. Modulated chlorophyll a fluorescenc
American Society of Plant Physiologists.
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23. Nitrogen and Carbon Flows Estimated by 15N and 13C Pulse-Chase Labeling during Regrowth of Alfalfa.
The flow of 15N and 13C from storage compounds in organs remaining after defoliation (sources) to regrowing tissue (sinks), and 13C losses through root or shoot respiration were assessed by pulse-chase labeling during regrowth of alfalfa (Medicago sativa L.) following shoot removal. A total of 73% of labeled C and 34% of labeled N were mobilized in source or
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24. Expression of Tryptophan Decarboxylase and Tyrosine Decarboxylase Genes in Tobacco Results in Altered Biochemical and Physiological Phenotypes1
The substrate specificity of tryptophan (Trp) decarboxylase (TDC) for Trp and tyrosine (Tyr) decarboxylase (TYDC) for Tyr was used to modify the in vivo pools of these amino acids in transgenic tobacco. Expression of TDC and TYDC was shown to deplete the levels of Trp and Tyr, respectively, during seedling development. The creation of artificial metabolic si
American Society of Plant Physiologists.