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  • 1
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We determined the proximate chemical composition as well as the construction costs of leaves of 27 species, grown at ambient and at a twice-ambient partial pressure of atmospheric CO2. These species comprised wild and agricultural herbaceous plants as well as tree seedlings. Both average responses across species and the range in response were considered. Expressed on a total dry weight basis, the main change in chemical composition due to CO2 was the accumulation of total non-structural carbohydrates (TNC). To a lesser extent, decreases were found for organic N compounds and minerals. Hardly any change was observed for total structural carbohydrates (cellulose plus hemicellulose), lignin and lipids. When expressed on a TNC-free basis, decreases in organic N compounds and minerals were still present. On this basis, there was also an increase in the concentration of soluble phenolics.In terms of glucose required for biosynthesis, the increase in costs for one chemical compound – TNC – was balanced by a decrease in the costs for organic N compounds. Therefore, the construction costs, the total amount of glucose required to produce 1 g of leaf, were rather similar for the two CO2 treatments; on average a small decrease of 3% was found. This decrease was attributable to a decrease of up to 30% in the growth respiration coefficient, the total CO2 respired [mainly for N AD(P)H and ATP] in the process of constructing 1 g of biomass. The main reasons for this reduction were the decrease in organic N compounds and the increase in TNC.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 184 (1992), S. 1241-1249 
    ISSN: 0006-291X
    Keywords: [abr] (RT-)PCR; (reverse transcription-) polymerase chain reaction ; [abr] DMSO; dimethylsulphoxide ; [abr] EC; embryonal carcinoma ; [abr] PTK; protein tyrosine kinase ; [abr] PTPase; protein tyrosine phosphatase ; [abr] RA; retinoic acid ; [abr] SDS; sodium dodecyl sulphate ; [abr] SSC; standard sodium citrate
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0014-4827
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Experimental Cell Research 196 (1991), S. 226-232 
    ISSN: 0014-4827
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0014-4827
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 184 (1992), S. 1241-1249 
    ISSN: 0006-291X
    Keywords: [abr] (RT-)PCR; (reverse transcription-) polymerase chain reaction ; [abr] DMSO; dimethylsulphoxide ; [abr] EC; embryonal carcinoma ; [abr] PTK; protein tyrosine kinase ; [abr] PTPase; protein tyrosine phosphatase ; [abr] RA; retinoic acid ; [abr] SDS; sodium dodecyl sulphate ; [abr] SSC; standard sodium citrate
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Doubling the atmospheric CO2 concentration from 350 to 700 μ1 1−1 increased the relative growth rate (RGR) of hydroponically grown Urtica dioica L. and Plantago major ssp. pleiosperma Pilger only for the first 10–14 days. Previous experiments with P. major led to the conclusion that RGR did not respond in proportion to the rate of photosynthesis. The present paper is focussed on the analysis of the impact of changes in leaf morphology, dry matter partitioning, dry matter chemical composition and ontogenetic drift on this discrepancy.Soon after the start of the treatment, carbohydrate concentrations were higher at elevated CO2: a reaction that was largely due to starch accumulation. An increase in the percentage of leaf dry matter and decreases in the specific leaf area (SLA) and the shoot nitrogen concentration were correlated with an increase in the total nonstructural carbohydrate concentration (TNC). A combination of accumulation of soluble sugars and starch and ontogenetic drift explains the decrease in SLA at the elevated CO2 level. A similar ontogenetic effect of elevated CO2 was observed on the specific root length (SRL). Other variables such as shoot nitrogen concentration and percentage leaf dry matter were not affected by correction of data for TNC levels. The net diurnal fluctuation of the carbohydrate pool in P. major was equal for both CO2 concentrations, indicating that the growth response to elevated CO2 may be ruled by variables other than photosynthesis, as for instance sink strength.Elevated CO2 did not greatly influence the partitioning of nitrogen between soluble and insoluble, reduced N and nitrate, nor the allocation of dry matter between leaf. stem and root. The finding that the root to shoot ratio (R/S) was not affected by elevated CO2 implies that, in order to maintain a balanced activity between roots and shoot, no shift in partitioning of dry matter upon doubling of the atmospheric CO2 concentration is required. Our data on R/S are in good agreement with the response of R/S to high CO2 predicted by models based on such a theorem.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Plant ecology 104-105 (1993), S. 99-115 
    ISSN: 1573-5052
    Keywords: Allocation ; Mycorrhiza ; N2 Fixation ; Nutrient limitation ; Root/Shoot Ratio ; Water limitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper examines the extent to which atmospheric CO2 enrichment may influence growth of plant roots and function in terms of uptake of water and nutrients, and carbon allocation towards symbionts. It is concluded that changes in dry matter allocation greatly depend on the experimental conditions during the experiment, the growth phase of the plant, and its morphological characteristics. Under non-limiting conditions of water and nutrients for growth, dry matter partitioning to the root is not changed by CO2 enrichment. The increase in root/shoot ratio, frequently observed under limiting conditions of water and/or nutrients, enables the plant to explore a greater soil volume, and hence acquire more water and nutrients. However, more data on changes in dry matter allocation within the root due to atmospheric CO2 are needed. It is concluded that nitrogen fixation is favored by CO2 enrichment since nodule mass is increased, concomitant with an increase in root length. The papers available so far on the influence of CO2 enrichment on mycorrhizal functioning suggest that carbon allocation to the roots might be increased, but also here more experiments are needed.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Plant ecology 104-105 (1993), S. 369-378 
    ISSN: 1573-5052
    Keywords: CO2-Enrichment ; Relative growth rate ; Dry matter allocation ; Photosynthesis ; Respiration ; Carbon balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The response ofPlantago major ssp,pleiosperma plants, grown on nutrient solution in a climate chamber, to a doubling of the ambient atmospheric CO2 concentration was investigated. Total dry matter production was increased by 30% after 3 weeks of exposure, due to a transient stimulation of the relative growth rate (RGR) during the first 10 days. Thereafter RGR returned to the level of control plants. Photosynthesis, expressed per unit leaf area, was stimulated during the first two weeks of the experiment, thereafter it dropped and nearly reached the level of the control plants. Root respiration was not affected by increased atmospheric CO2 levels, whereas shoot, dark respiration was stimulated throughout the experimental period. Dry matter allocation over leaves stems and roots was not affected by the CO2 level. SLA was reduced by 10%, which can partly be explained by an increased dry matter content of the leaves. Both in the early and later stages of the experiment, shoot respiration accounted for a larger part of the carbon budget in plants grown at elevated atmospheric CO2. Shifts in the total carbon budget were mainly due to the effects on shoot respiration. Leaf growth accounted for nearly 50% of the C budget at all stages of the experiment and in both treatments.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1439-6327
    Keywords: Catecholamines ; Renin ; Splenectomy ; Exercise ; Conscious dog
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The influence of splenectomy in the dog on plasma catecholamine levels and plasma renin activity during treadmill running and swimming was investigated. Plasma catecholamines were measured by a radioenzymatic assay and plasma renin activity by a radioimmunoassay. Exercise consistently increased plasma catecholamine levels before and after splenectomy (range of increase:3–38 pmol·ml−1). Swimming, however, was a stronger stimulus than running. No change in the ratio between noradrenaline and adrenaline was found. In intact dogs exercise results in a marked increase in hematocrit due to splenic contraction (range of increase 3–8 volume %), while renal blood flow and plasma renin activity remain virtually constant. In splenectomized dogs, exercise has been reported to induce a decrease in renal blood flow. In contrast to this known effect on renal blood flow, splenectomy did not affect plasma renin activity in treadmill running dogs. In swimming dogs, however, plasma renin activity was increased after splenectomy (range of increase 3.3–6.9 ng·Ang I·ml−1·h−1). Possibly, a threshold in sympathetic tone is required to increase renin release in the dog.
    Type of Medium: Electronic Resource
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