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  • 1
    Electronic Resource
    Electronic Resource
    IDENTIFICATION AND QUANTIFICATION OF 3-METHOXY-4-HYDROXYPHENYLETHANOL (MOPET) IN HUMAN CEREBROSPINAL FLUID AND RAT BRAIN BY MEANS OF GAS CHROMATOGRAPHY-MASS SPECTROMETRY (1978)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 30 (1978), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— The identification of 3-methoxy-4-hydroxyphenylethanol (MOPET) in human cerebrospinal fluid and in rat brain is described. Use was made of the high sensitivity and selectivity provided by gas chromatography-mass spectrometry. Concentrations of MOPET in human cerebrospinal fluid, rat brain and rat urine together with those of some other catecholamine metabolites are given. The effect of intraperitoneal administration of deuterium-labelled MOPET and haloperidol on rat brain and urine MOPET levels was studied. The quantitative importance of MOPET as an end product of central and peripheral dopamine metabolism in man and rat is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1978.tb10483.x
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  • 2
    Electronic Resource
    Electronic Resource
    MORE EFFICIENT PLANTS: A Consequence of Rising Atmospheric CO2? (1997)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Plant Physiology and Plant Molecular Biology 48 (1997), S. 609-639 
    Details
    ISSN: 1040-2519
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract The primary effect of the response of plants to rising atmospheric CO2 (Ca) is to increase resource use efficiency. Elevated Ca reduces stomatal conductance and transpiration and improves water use efficiency, and at the same time it stimulates higher rates of photosynthesis and increases light-use efficiency. Acclimation of photosynthesis during long-term exposure to elevated Ca reduces key enzymes of the photosynthetic carbon reduction cycle, and this increases nutrient use efficiency. Improved soil-water balance, increased carbon uptake in the shade, greater carbon to nitrogen ratio, and reduced nutrient quality for insect and animal grazers are all possibilities that have been observed in field studies of the effects of elevated Ca. These effects have major consequences for agriculture and native ecosystems in a world of rising atmospheric Ca and climate change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.arplant.48.1.609
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  • 3
    Electronic Resource
    Electronic Resource
    Unstable intermediates. 5. Thioketene (1977)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 99 (1977), S. 1663-1664 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00447a073
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of elevated atmospheric CO2 on root decomposition in a scrub oak ecosystem (2001)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 7 (2001), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: The effects of elevated atmospheric CO2 on fine root decomposition over a 828-day period were investigated using open top chambers with both ambient and elevated (700 ppm) CO2 treatments in an oak–palmetto scrub ecosystem at Kennedy Space Center, Florida. Carbon dioxide enrichment of the chambers began 15 May 1996. The experiment included roots grown in ambient and elevated carbon dioxide. Vertical litterbags installed in September 1996 in each elevated and ambient chamber incubated from December 1996 to December 1998 showed no significant treatment effect on fine root or rhizome mass loss. Initial fine root percentage mass loss varied from 10.3% to 13.5% after three months; 55.5% to 38.3% of original mass had been lost after 828 days. A period of nitrogen immobilization occurred in both fine roots and rhizomes in the elevated CO2 incubation, which is a potential mechanism for nitrogen conservation for this system in an elevated CO2 world.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1354-1013.2001.00428.x
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  • 5
    Electronic Resource
    Electronic Resource
    Elevated atmospheric CO2 stimulates aboveground biomass in a fire-regenerated scrub-oak ecosystem (2002)
    Oxford, UK : Blackwell Science, Ltd
    Global change biology 8 (2002), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: The effect of elevated atmospheric CO2 concentration (Ca) on the aboveground biomass of three oak species, Quercus myrtifolia, Q. geminata, and Q. chapmanii, was estimated nondestructively using allometric relationships between stem diameter and aboveground biomass after four years of experimental treatment in a naturally fire-regenerated scrub-oak ecosystem. After burning a stand of scrub-oak vegetation, re-growing plants were exposed to either current ambient (379 µL L−1 CO2) or elevated (704 µL L−1 CO2) Ca in 16 open-top chambers over a four-year period, and measurements of stem diameter were carried out annually on all oak shoots within each chamber. Elevated Ca significantly increased aboveground biomass, expressed either per unit ground area or per shoot; elevated Ca had no effect on shoot density. The relative effect of elevated Ca on aboveground biomass increased each year of the study from 44% (May 96–Jan 97), to 55% (Jan 97–Jan 98), 66% (Jan 98–Jan 99), and 75% (Jan 99–Jan 00). The effect of elevated Ca was species specific: elevated Ca significantly increased aboveground biomass of the dominant species, Q. myrtifolia, and tended to increase aboveground biomass of Q. chapmanii, but had no effect on aboveground biomass of the subdominant, Q. geminata. These results show that rising atmospheric CO2 has the potential to stimulate aboveground biomass production in ecosystems dominated by woody species, and that species-specific growth responses could, in the long term, alter the composition of the scrub-oak community.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1354-1013.2001.00458.x
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  • 6
    Electronic Resource
    Electronic Resource
    Elevated CO2 increases nitrogen fixation and decreases soil nitrogen mineralization in Florida scrub oak (1999)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 5 (1999), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: We report changes in nitrogen cycling in Florida scrub oak in response to elevated atmospheric CO2 during the first 14 months of experimental treatment. Elevated CO2 stimulated above-ground growth, nitrogen mass, and root nodule production of the nitrogen-fixing vine, Galactia elliottii Nuttall. During this period, elevated CO2 reduced rates of gross nitrogen mineralization in soil, and resulted in lower recovery of nitrate on resin lysimeters. Elevated CO2 did not alter nitrogen in the soil microbial biomass, but increased the specific rate of ammonium immobilization (NH4+ immobilized per unit microbial N) measured over a 24-h period. Increased carbon input to soil through greater root growth combined with a decrease in the quality of that carbon in elevated CO2 best explains these changes. These results demonstrate that atmospheric CO2 concentration influences both the internal cycling of nitrogen (mineralization, immobilization, and nitrification) as well as the processes that regulate total ecosystem nitrogen mass (nitrogen fixation and nitrate leaching) in Florida coastal scrub oak. If these changes in nitrogen cycling are sustained, they could cause long-term feedbacks to the growth responses of plants to elevated CO2. Greater nitrogen fixation and reduced leaching could stimulate nitrogen-limited plant growth by increasing the mass of labile nitrogen in the ecosystem. By contrast, reduced nitrogen mineralization and increased immobilization will restrict the supply rate of plant-available nitrogen, potentially reducing plant growth. Thus, the net feedback to plant growth will depend on the balance of these effects through time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.1999.00275.x
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of elevated atmospheric CO2 on net ecosystem CO2 exchange of a scrub–oak ecosystem (2003)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 9 (2003), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: We report the results of a 2-year study of effects of the elevated (current ambient plus 350 μmol CO2 mol−1) atmospheric CO2 concentration (Ca) on net ecosystem CO2 exchange (NEE) of a scrub–oak ecosystem. The measurements were made in open-top chambers (OTCs) modified to function as open gas-exchange systems. The OTCs enclosed samples of the ecosystem (ca. 10 m2 surface area) that had regenerated after a fire, 5 years before, in either current ambient or elevated Ca. Throughout the study, elevated Ca increased maximum NEE (NEEmax) and the apparent quantum yield of the NEE (φNEE) during the photoperiod. The magnitude of the stimulation of NEEmax, expressed per unit ground area, was seasonal, rising from 50% in the winter to 180% in the summer. The key to this stimulation was effects of elevated Ca, and their interaction with the seasonal changes in the environment, on ecosystem leaf area index, photosynthesis and respiration. The separation of these factors was difficult. When expressed per unit leaf area the stimulation of the NEEmax ranged from 7% to 60%, with the increase being dependent on increasing soil water content (Wsoil). At night, the CO2 effluxes from the ecosystem (NEEnight) were on an average 39% higher in elevated Ca. However, the increase varied between 6% and 64%, and had no clear seasonality. The partitioning of NEEnight into its belowground (Rbelow) and aboveground (Rabove) components was carried out in the winter only. A 35% and 27% stimulation of NEEnight in December 1999 and 2000, respectively, was largely due to a 26% and 28% stimulation of Rbelow in the respective periods, because Rbelow constituted ca. 87% of NEEnight. The 37% and 42% stimulation of Rabove in December 1999 and 2000, respectively, was less than the 65% and 80% stimulation of the aboveground biomass by elevated Ca at these times. An increase in the relative amount of the aboveground biomass in woody tissue, combined with a decrease in the specific rate of stem respiration of the dominant species Quercus myrtifolia in elevated Ca, was responsible for this effect. Throughout this study, elevated Ca had a greater effect on carbon uptake than on carbon loss, in terms of both the absolute flux and relative stimulation. Consequently, for this scrub–oak ecosystem carbon sequestration was greater in the elevated Ca during this 2-year study period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2486.2003.00675.x
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  • 8
    Electronic Resource
    Electronic Resource
    Seasonal variability in the effect of elevated CO2 on ecosystem leaf area index in a scrub-oak ecosystem (2002)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 8 (2002), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: We report effects of elevated atmospheric CO2 concentration (Ca) on leaf area index (LAI) of a Florida scrub-oak ecosystem, which had regenerated after fire for between three and five years in open-top chambers (OTCs) and was yet to reach canopy closure. LAI was measured using four nondestructive methods, calibrated and tested in experiments performed in calibration plots near the OTCs. The four methods were: PAR transmission through the canopy, normalized difference vegetation index (NDVI), hemispherical photography, and allometric relationships between plant stem diameter and plant leaf area. Calibration experiments showed: (1) Leaf area index could be accurately determined from either PAR transmission through the canopy or hemispherical photography. For LAI determined from PAR transmission through the canopy, ecosystem light extinction coefficient (k) varied with season and was best described as a function of PAR transmission through the canopy. (2) A negative exponential function described the relationship between NDVI and LAI; (3) Allometric relationships overestimated LAI. Throughout the two years of this study, LAI was always higher in elevated Ca, rising from, 20% during winter, to 55% during summer. This seasonality was driven by a more rapid development of leaf area during the spring and a relatively greater loss of leaf area during the winter, in elevated Ca. For this scrub-oak ecosystem prior to canopy closure, increased leaf area was an indirect mechanism by which ecosystem C uptake and canopy N content were increased in elevated Ca. In addition, increased LAI decreased potential reductions in canopy transpiration from decreases in stomatal conductance in elevated Ca. These findings have important implications for biogeochemical cycles of C, N and H2O in woody ecosystems regenerating from disturbance in elevated Ca.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2002.00526.x
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of elevated atmospheric CO2 concentration on C and N pools and rhizosphere processes in a Florida scrub oak community (2000)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 6 (2000), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: The effect of elevated atmospheric CO2 concentration (Ca) on soil carbon and nitrogen accumulation and soil microbial biomass and activity in a native Florida scrub oak community was studied. The plant community, dominated by Quercus myrtifolia Willd. and Q. geminata Small, was exposed for 2 years to elevated Ca in open-top chambers. Buried subsoil bags were retrieved after 1 year of exposure to elevated Ca. In addition, soil cores were taken twice from the chambers within two weeks in July 1998 (the first after a long dry spell and the second after 25 mm of rainfall) and divided into rhizosphere and bulk soil. Soil organic matter accumulation (excluding roots) into the buried subsoil bags was lower in elevated than in ambient Ca. Concentrations of soluble carbon and ninhydrin-reactive nitrogen (Nninh) in the rhizosphere soil were reduced by elevated Ca for the first sampling date and unaffected for the second sampling date. Microbial activity, measured as fluorescein diacetate (FDA) hydrolysis, decreased in elevated Ca for the first sampling date. Microbial biomass carbon and nitrogen in the bulk soil were unaffected by elevated Ca. There was no effect of elevated Ca on bacterial numbers in the rhizosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.2000.00317.x
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  • 10
    Electronic Resource
    Electronic Resource
    Seventeen years of elevated CO2 exposure in a Chesapeake Bay Wetland: sustained but contrasting responses of plant growth and CO2 uptake (2005)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 11 (2005), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Increased atmospheric CO2 concentration (Ca) produces a short-term stimulation of photosynthesis and plant growth across terrestrial ecosystems. However, the long-term response remains uncertain and is thought to depend on environmental constraints. In the longest experiment on natural ecosystem response to elevated Ca, we measured the shoot-density, biomass and net CO2 exchange (NEE) responses to elevated Ca from 1987 to 2003 in a Scirpus olneyi wetland sedge community of the Chesapeake Bay, MD, USA. Measurements were conducted in five replicated open-top chambers per CO2 treatment (ambient and elevated). In addition, unchambered control plots were monitored for shoot density. Responses of daytime NEE, Scirpus plant biomass and shoot density to elevated Ca were positive for any single year of the 17-year period of study. Daytime NEE stimulation by elevated Ca rapidly dropped from 80% at the onset of the experiment to a long-term stimulation average of about 35%. Shoot-density stimulation by elevated Ca increased linearly with duration of exposure (r2=0.89), exceeding 120% after 17 years. Although of lesser magnitude, the shoot biomass response to elevated Ca was similar to that of the shoot density. Daytime NEE response to elevated Ca was not explained by the duration of exposure, but negatively correlated with salinity of the marsh, indicating that this elevated-Ca response was decreased by water-related stress. By contrast, circumstantial evidence suggested that salinity stress increased the stimulation of shoot density by elevated Ca, which highlights the complexity of the interaction between water-related stresses and plant community responses to elevated Ca. Notwithstanding the effects of salinity stress, we believe that the most important finding of the present research is that a species response to elevated Ca can continually increase when this species is under stress and declining in its natural environment. This is particularly important because climate changes associated with elevated Ca are likely to increase environmental stresses on numerous species and modify their present distribution. Our results point to an increased resilience to change under elevated Ca when plants are exposed to adverse environmental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2486.2005.00913.x
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