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  • 1
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    Elemental stoichiometry and photophysiology regulation of Synechococcus sp. PCC7002 under increasing severity of chronic iron limitation (2018)
    In:  EPIC3Plant & Cell Physiology
    Details
    Publication Date: 2018-07-19
    Description: Iron (Fe) is an essential cofactor for many metabolic enzymes of photoautotrophs. Although Fe limits phytoplankton productivity in broad areas of the ocean, phytoplankton have adapted their metabolism and growth to survive in these conditions. Using the euryhaline cyanobacterium Synechococcus sp. PCC7002, we investigated the physiological responses to long-term acclimation to four levels of Fe availability representative of the contemporary ocean (36.7, 3.83, 0.47 and 0.047 pM Fe’). With increasing severity of Fe limitation, Synechococcus sp. cells gradually decreased their volume and growth while increasing their energy allocation into organic carbon and nitrogen cellular pools. Furthermore, the total cellular content of pigments decreased. Additionally, with increasing severity of Fe limitation, intertwined responses of PSII functional cross-section (sPSII), re-oxidation time of the plastoquinone primary acceptor QA (t) and non-photochemical quenching revealed a shift in the photophysiological response between mild to strong Fe limitation compared with severe limitation. Under mild and strong Fe limitation, there was a decrease in linear electron transport accompanied by progressive loss of state transitions. Under severe Fe limitation, state transitions seemed to be largely supplanted by alternative electron pathways. In addition, mechanisms to dissipate energy excess and minimize oxidative stress associated with high irradiances increased with increasing severity of Fe limitation. Overall, our results establish the sequence of physiological strategies adopted by the cells under increasing severity of chronic Fe limitation, within a range of Fe concentrations relevant to modern ocean biogeochemistry.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 2
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    Seawater carbonate chemistry and growth and particulate organic nitrogen production of diatom Thalassiosira pseudonana (2020)
    PANGAEA
    Details
    Publication Date: 2024-03-15
    Description: Phytoplankton in the upper oceans are exposed to changing light levels due to mixing, diurnal solar cycles and weather conditions. Consequently, effects of ocean acidification are superimposed upon responses to variable light levels. We therefore grew a model diatom Thalassiosira pseudonana under either constant or variable light but at the same daily photon dose, with current low (400 μatm, LC) and future high CO2 (1000 μatm, HC) treatments. Variable light, compared with the constant light regime, decreased the growth rate, Chl a, Chl c, and carotenoid contents under both LC and HC conditions. Cells grown under variable light appeared more tolerant of high light as indicated by higher maximum relative electron transport rate and saturation light. Light variation interacted with high CO2/lowered pH to decrease the carbon fixation rate, but increased particulate organic carbon (POC) and particularly nitrogen (PON) per cell, which drove a decrease in C/N ratio, reflecting changes in the efficiency of energy transfer from photo-chemistry to net biomass production. Our results imply that elevated pCO2 under varying light conditions can lead to less primary productivity but more PON per biomass of the diatom, which might improve the food quality of diatoms and thereby influence biogeochemical nitrogen cycles.
    Keywords: Alkalinity, total; Alkalinity, total, standard deviation; Aragonite saturation state; Aragonite saturation state, standard deviation; Bicarbonate ion; Bicarbonate ion, standard deviation; Biomass/Abundance/Elemental composition; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calcite saturation state, standard deviation; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Calculated using seacarb after Orr et al. (2018); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbon, organic, particulate; Carbon, organic, particulate, per cell; Carbon, organic, particulate, standard deviation; Carbon/Nitrogen ratio; Carbon/Nitrogen ratio, standard deviation; Carbonate ion; Carbonate ion, standard deviation; Carbonate system computation flag; Carbon dioxide; Carbon dioxide, standard deviation; Carbon fixation rate; Carbon fixation rate, standard deviation; Carotenoids, intracellular; Carotenoids, standard deviation; Carotenoids/Chlorophyll a ratio; Carotenoids/Chlorophyll a ratio, standard deviation; Carotenoids per cell; Cell size; Cell size, standard deviation; Chlorophyll a, intracellular; Chlorophyll a, standard deviation; Chlorophyll a per cell; Chlorophyll c, intracellular; Chlorophyll c, standard deviation; Chlorophyll c per cell; Chromista; Effective quantum yield; Effective quantum yield, standard deviation; Electron transport rate, relative; Electron transport rate, relative, standard deviation; Electron transport rate efficiency; Electron transport rate efficiency, standard deviation; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Fugacity of carbon dioxide in seawater, standard deviation; Growth/Morphology; Growth rate; Growth rate, standard deviation; Irradiance; Laboratory experiment; Laboratory strains; Light; Light saturation point; Light saturation point, standard deviation; Maximal electron transport rate, relative; Maximal electron transport rate, relative, standard deviation; Nitrogen, organic, particulate; Nitrogen, organic, particulate, per cell; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Ochrophyta; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Particulate organic carbon, production, standard deviation; Particulate organic carbon production per cell; Particulate organic nitrogen, standard deviation; Particulate organic nitrogen production, standard deviation; pH; pH, standard deviation; Phytoplankton; Primary production/Photosynthesis; Production of particulate organic carbon; Production of particulate organic nitrogen; Registration number of species; Salinity; Single species; Species; Temperature, water; Thalassiosira pseudonana; Time of day; Total carbon fixation per cell per hour; Treatment; Type; Uniform resource locator/link to reference
    Type: Dataset
    Format: text/tab-separated-values, 2936 data points
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  • 3
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    Seawater carbonate chemistry and photosystem II photoinactivation of the coastal diatom Thalassiosira pseudonana in a laboratory experiment (2013)
    PANGAEA
    In:  Supplement to: Li, Gang; Campbell, Douglas A (2013): Rising CO2 Interacts with Growth Light and Growth Rate to Alter Photosystem II Photoinactivation of the Coastal Diatom Thalassiosira pseudonana. PLoS ONE, 8(1), e55562, https://doi.org/10.1371/journal.pone.0055562.t001
    Details
    Publication Date: 2024-03-15
    Description: We studied the interactive effects of pCO2 and growth light on the coastal marine diatom Thalassiosira pseudonana CCMP 1335 growing under ambient and expected end-of-the-century pCO2 (750 ppmv), and a range of growth light from 30 to 380 µmol photons/m**2/s. Elevated pCO2 significantly stimulated the growth of T. pseudonana under sub-saturating growth light, but not under saturating to super-saturating growth light. Under ambient pCO2 susceptibility to photoinactivation of photosystem II (sigma i) increased with increasing growth rate, but cells growing under elevated pCO2 showed no dependence between growth rate and sigma i, so under high growth light cells under elevated pCO2 were less susceptible to photoinactivation of photosystem II, and thus incurred a lower running cost to maintain photosystem II function. Growth light altered the contents of RbcL (RUBISCO) and PsaC (PSI) protein subunits, and the ratios among the subunits, but there were only limited effects on these and other protein pools between cells grown under ambient and elevated pCO2.
    Keywords: Alkalinity, total; Aragonite saturation state; Bicarbonate ion; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, organic, particulate, per cell; Carbon/Nitrogen ratio; Carbon and nitrogen and sulfur (CNS) element analyzer, Elementar, Vario EL; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Cell biovolume; Cell density; CF1 subunit of ATP synthase protein; Chlorophyll a per cell; Chromista; Cytochrome c1; Date; Effective absorbance cross-section of photosystem II; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Growth rate; Identification; Irradiance; Laboratory experiment; Laboratory strains; Light; Nitrogen, organic, particulate, per cell; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Ochrophyta; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phosphate; Photochemical quenching; Photospectrometer, methylene blue; Photosynthetic protein PsbA; Photosynthetic protein PsbD; Photosynthetic protein Rubisco; Phytoplankton; Potentiometric titration; Primary production/Photosynthesis; Protein per cell; Replicates; Salinity; Silicate; Single species; Species; Temperature, water; Thalassiosira pseudonana; Time in minutes; Treatment
    Type: Dataset
    Format: text/tab-separated-values, 1542 data points
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    DATA PANGAEA
  • 4
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    Seawater carbonate chemistry and photosynthesis of a coccolithophorid in a laboratory experiment (2013)
    PANGAEA
    In:  Supplement to: Jin, Peng; Gao, Kunshan; Villafañe, Virginia E; Campbell, Douglas A; Helbling, E Walter (2013): Ocean Acidification Alters the Photosynthetic Responses of a Coccolithophorid to Fluctuating Ultraviolet and Visible Radiation. Plant Physiology, 162(4), 2084-2094, https://doi.org/10.1104/pp.113.219543
    Details
    Publication Date: 2024-03-15
    Description: Mixing of seawater subjects phytoplankton to fluctuations in photosynthetically active radiation (400-700 nm) and ultraviolet radiation (UVR; 280-400 nm). These irradiance fluctuations are now superimposed upon ocean acidification and thinning of the upper mixing layer through stratification, which alters mixing regimes. Therefore, we examined the photosynthetic carbon fixation and photochemical performance of a coccolithophore, Gephyrocapsa oceanica, grown under high, future (1,000 µatm) and low, current (390 µatm) CO2 levels, under regimes of fluctuating irradiances with or without UVR. Under both CO2 levels, fluctuating irradiances, as compared with constant irradiance, led to lower nonphotochemical quenching and less UVR-induced inhibition of carbon fixation and photosystem II electron transport. The cells grown under high CO2 showed a lower photosynthetic carbon fixation rate but lower nonphotochemical quenching and less ultraviolet B (280-315 nm)-induced inhibition. Ultraviolet A (315-400 nm) led to less enhancement of the photosynthetic carbon fixation in the high-CO2-grown cells under fluctuating irradiance. Our data suggest that ocean acidification and fast mixing or fluctuation of solar radiation will act synergistically to lower carbon fixation by G. oceanica, although ocean acidification may decrease ultraviolet B-related photochemical inhibition.
    Keywords: Alkalinity, total; Alkalinity, total, standard deviation; Aragonite saturation state; Bicarbonate ion; Bicarbonate ion, standard deviation; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbonate ion; Carbonate ion, standard deviation; Carbonate system computation flag; Carbon dioxide; Chromista; Description; Effective absorbance cross-section of photosystem II; Electron transport, absolute, cumulative; Electron transport rate, absolute; Experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Gephyrocapsa oceanica; Haptophyta; Identification; Irradiance; Laboratory experiment; Laboratory strains; Light; Light absorption by phytoplankton per chlorophyll a; Non photochemical quenching; North Pacific; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; Percentage; pH; pH, standard deviation; Phytoplankton; Potentiometric; Primary production; Primary production, cumulative; Primary production/Photosynthesis; Primary production of carbon; Replicates; Salinity; Single species; Species; Temperature, water; Time in minutes; Treatment; Ultraviolet radiation-induced inhibition of photosynthesis; Wavelength
    Type: Dataset
    Format: text/tab-separated-values, 138064 data points
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  • 5
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    The nitrogen costs of photosynthesis in a diatom under current and future pCO2 (2015)
    PANGAEA
    In:  Supplement to: Li, Gang; Brown, Christopher M; Jeans, Jennifer A; Donaher, Natalie A; McCarthy, Avery; Campbell, Douglas A (2015): The nitrogen costs of photosynthesis in a diatom under current and future pCO2. New Phytologist, 205(2), 533-543, https://doi.org/10.1111/nph.13037
    Details
    Publication Date: 2024-03-15
    Description: With each cellular generation, oxygenic photoautotrophs must accumulate abundant protein complexes that mediate light capture, photosynthetic electron transport and carbon fixation. In addition to this net synthesis, oxygenic photoautotrophs must counter the light-dependent photoinactivation of Photosystem II (PSII), using metabolically expensive proteolysis, disassembly, resynthesis and re-assembly of protein subunits. We used growth rates, elemental analyses and protein quantitations to estimate the nitrogen (N) metabolism costs to both accumulate the photosynthetic system and to maintain PSII function in the diatom Thalassiosira pseudonana, growing at two pCO2 levels across a range of light levels. The photosynthetic system contains c. 15-25% of total cellular N. Under low growth light, N (re)cycling through PSII repair is only c. 1% of the cellular N assimilation rate. As growth light increases to inhibitory levels, N metabolite cycling through PSII repair increases to c. 14% of the cellular N assimilation rate. Cells growing under the assumed future 750 ppmv pCO2 show higher growth rates under optimal light, coinciding with a lowered N metabolic cost to maintain photosynthesis, but then suffer greater photoinhibition of growth under excess light, coincident with rising costs to maintain photosynthesis. We predict this quantitative trait response to light will vary across taxa.
    Keywords: Alkalinity, total; Aragonite saturation state; Bicarbonate ion; Biomass/Abundance/Elemental composition; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Cell biovolume; Chlorophyll a per cell; Chlorophyll c per cell; Chromista; Cytochrome c1; Fucoxanthin chlorophyll protein per cell; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Growth rate; Identification; Irradiance; Laboratory experiment; Laboratory strains; Light; Nitrogen content per cell; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Ochrophyta; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phosphate; Photosynthetic protein, PsbC; Photosynthetic protein PsbA; Photosynthetic protein PsbD; Photosynthetic protein Rubisco; Phytoplankton; Potentiometric; Primary production/Photosynthesis; Protein per cell; Ratio; Salinity; Silicate; Single species; Species; Temperature, water; Thalassiosira pseudonana; Treatment
    Type: Dataset
    Format: text/tab-separated-values, 1536 data points
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  • 6
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    Seawater carbonate chemistry and CO2 acquisition efficiency and mitochondrial respiration in a coastal diatom (2021)
    PANGAEA
    Details
    Publication Date: 2024-03-15
    Description: Diatom responses to ocean acidification have been documented with variable and controversial results. We grew the coastal diatom Thalassiosira weissflogii under 410 (LC, pH 8.13) vs 1000 μatm (HC, pH 7.83) pCO2 and at different levels of light (80, 140, 220 μmol photons/m**2/s), and found that light level alters physiological responses to OA. CO2 concentrating mechanisms (CCMs) were down-regulated in the HC-grown cells across all the light levels, as reflected by lowered activity of the periplasmic carbonic anhydrase and decreased photosynthetic affinity for CO2 or dissolved inorganic carbon. The specific growth rate was, however, enhanced significantly by 9.2% only at the limiting low light level. These results indicate that rather than CO2 “fertilization”, the energy saved from down-regulation of CCMs promoted the growth rate of the diatom when light availability is low, in parallel with enhanced respiration under OA to cope with the acidic stress by providing extra energy.
    Keywords: Alkalinity, total; Alkalinity, total, standard deviation; Aragonite saturation state; Aragonite saturation state, standard deviation; Bicarbonate ion; Bicarbonate ion, standard deviation; Bottles or small containers/Aquaria (〈20 L); Calcification/Dissolution; Calcite saturation state; Calcite saturation state, standard deviation; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Calculated using seacarb after Orr et al. (2018); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbonate ion; Carbonate ion, standard deviation; Carbonate system computation flag; Carbon dioxide; Carbon dioxide, standard deviation; Carotenoids, standard deviation; Carotenoids/Chlorophyll a ratio; Carotenoids/Chlorophyll a ratio, standard deviation; Carotenoids per cell; Cell size; Cell size, standard deviation; Chlorophyll a, standard deviation; Chlorophyll a per cell; Chromista; Effective quantum yield; Effective quantum yield, standard deviation; Electron transport rate, relative; Electron transport rate, relative, standard deviation; Electron transport rate efficiency; Electron transport rate efficiency, standard deviation; Extracellular carbonic anhydrase activity, per cell; Extracellular carbonic anhydrase activity, standard deviation; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Fugacity of carbon dioxide in seawater, standard deviation; Growth/Morphology; Growth rate; Growth rate, standard deviation; Laboratory experiment; Laboratory strains; Light; Light saturation point; Light saturation point, standard deviation; Maximal electron transport rate, relative; Maximal electron transport rate, relative, standard deviation; Maximum quantum yield of photosystem II; Maximum quantum yield of photosystem II, standard deviation; Net photosynthesis rate, oxygen, per cell; Net photosynthesis rate, oxygen, per chlorophyll a; Net photosynthesis rate, standard deviation; Non photochemical quenching; Non photochemical quenching, standard deviation; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Ochrophyta; Oxygen evolution, daytime; Oxygen evolution, daytime, standard deviation; Oxygen evolution per cell, daytime; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; pH, standard deviation; Phytoplankton; Primary production/Photosynthesis; Ratio; Ratio, standard deviation; Registration number of species; Respiration; Respiration rate, oxygen, per cell; Respiration rate, oxygen, per chlorophyll a; Respiration rate, oxygen, standard deviation; Salinity; Single species; Species; Temperature, water; Thalassiosira weissflogii; Time in days; Treatment; Type; Uniform resource locator/link to reference
    Type: Dataset
    Format: text/tab-separated-values, 4428 data points
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  • 7
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    Seawater carbonate chemistry and the photophysiology of Thalassiosira pseudonana (Bacillariophyceae) and Emiliania huxleyi (Haptophyta) in a laboratory experiment (2012)
    PANGAEA
    In:  Supplement to: McCarthy, Avery; Rogers, Susan P; Duffy, Stephen J; Campbell, Douglas A (2012): Elevated carbon dioxide differentially alters the photophysiology of Thalassiosira pseudonana (Bacillariophyceae) and Emiliania huxleyi (Haptophyta). Journal of Phycology, 48(3), 635-646, https://doi.org/10.1111/j.1529-8817.2012.01171.x
    Details
    Publication Date: 2024-03-18
    Description: Increasing anthropogenic carbon dioxide is causing changes to ocean chemistry, which will continue in a predictable manner. Dissolution of additional atmospheric carbon dioxide leads to increased concentrations of dissolved carbon dioxide and bicarbonate and decreased pH in ocean water. The concomitant effects on phytoplankton ecophysiology, leading potentially to changes in community structure, are now a focus of concern. Therefore, we grew the coccolithophore Emiliania huxleyi (Lohmann) W. W. Hay et H. Mohler and the diatom strains Thalassiosira pseudonana (Hust.) Hasle et Heimdal CCMP 1014 and T. pseudonana CCMP 1335 under low light in turbidostat photobioreactors bubbled with air containing 390 ppmv or 750 ppmv CO2. Increased pCO2 led to increased growth rates in all three strains. In addition, protein levels of RUBISCO increased in the coastal strains of both species, showing a larger capacity for CO2 assimilation at 750 ppmv CO2. With increased pCO2, both T. pseudonana strains displayed an increased susceptibility to PSII photoinactivation and, to compensate, an augmented capacity for PSII repair. Consequently, the cost of maintaining PSII function for the diatoms increased at increased pCO2. In E. huxleyi, PSII photoinactivation and the counter-acting repair, while both intrinsically larger than in T. pseudonana, did not change between the current and high-pCO2 treatments. The content of the photosynthetic electron transport intermediary cytochrome b6/f complex increased significantly in the diatoms under elevated pCO2, suggesting changes in electron transport function.
    Keywords: Alkalinity, total; Aragonite saturation state; Bicarbonate ion; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, organic, particulate, per cell; Carbon/Nitrogen ratio; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Cell biovolume; Cell density; CF1 subunit of ATP synthase protein; Chlorophyll a; Chlorophyll c1/chlorophyll a ratio; Chlorophyll c2/chlorophyll a ratio; Chlorophyll c3/chlorophyll a ratio; Chromista; Cytochrome c1; Diadinoxanthin/chlorophyll a ratio; Diatoxanthin/chlorophyll a ratio; Effective absorbance cross-section of photosystem II; Emiliania huxleyi; Fucoxanthin/chlorophyll a ratio; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Growth rate; Haptophyta; Identification; Irradiance; Laboratory experiment; Laboratory strains; Non photochemical quenching; North Atlantic; OA-ICC; Ocean Acidification International Coordination Centre; Ochrophyta; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phosphate; Photochemical quenching; Photosynthetic protein, PsbC; Photosynthetic protein PsbA; Photosynthetic protein PsbD; Photosynthetic protein Rubisco; Phytoplankton; Potentiometric; Primary production/Photosynthesis; Protein per cell; Replicates; Salinity; Silicate; Single species; Species; Strain; Temperature, water; Thalassiosira pseudonana; Time in minutes; Treatment
    Type: Dataset
    Format: text/tab-separated-values, 1086 data points
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  • 8
    Electronic Resource
    Electronic Resource
    Origins of sulphate in Antarctic dry-valley soils as deduced from anomalous 17 O compositions (2000)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 407 (2000), S. 499-502 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The dry valleys of Antarctica are some of the oldest terrestrial surfaces on the Earth. Despite much study of soil weathering and development, ecosystem dynamics and the occurrence of life in these extreme environments, the reasons behind the exceptionally high salt content of the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35035054
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  • 9
    Electronic Resource
    Electronic Resource
    Anomalous 17 O compositions in massive sulphate deposits on the Earth (2000)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 406 (2000), S. 176-178 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The variation of δ18O that results from nearly all physical, biological and chemical processes on the Earth is approximately twice as large as the variation of δ17O. This so-called ‘mass-dependent’ fractionation is well documented ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35018052
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  • 10
    Electronic Resource
    Electronic Resource
    Intermittent low temperatures constrain spring recovery of photosynthesis in boreal Scots pine forests (2004)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 10 (2004), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: During winter and early spring, evergreen boreal conifers are severely stressed because light energy cannot be used when photosynthesis is pre-empted by low ambient temperatures. To study photosynthetic performance dynamics in a severe boreal climate, seasonal changes in photosynthetic pigments, chloroplast proteins and photochemical efficiency were studied in a Scots pine forest near Zotino, Central Siberia. In winter, downregulation of photosynthesis involved loss of chlorophylls, a twofold increase in xanthophyll cycle pigments and sustained high levels of the light stress-induced zeaxanthin pigment. The highest levels of xanthophylls and zeaxanthin did not occur during the coldest winter period, but rather in April when light was increasing, indicating an increased capacity for thermal dissipation of excitation energy at that time. Concomitantly, in early spring the D1 protein of the photosystem II (PSII) reaction centre and the light-harvesting complex of PSII dropped to their lowest annual levels. In April and May, recovery of PSII activity, chloroplast protein synthesis and rearrangements of pigments were observed as air temperatures increased above 0°C. Nevertheless, severe intermittent low-temperature episodes during this period not only halted but actually reversed the physiological recovery. During these spring low-temperature episodes, protective processes involved a complementary function of the PsbS and early light-induced protein thylakoid proteins. Full recovery of photosynthesis did not occur until the end of May. Our results show that even after winter cold hardening, photosynthetic activity in evergreens responds opportunistically to environmental change throughout the cold season. Therefore, climate change effects potentially improve the sink capacity of boreal forests for atmospheric carbon. However, earlier photosynthesis in spring in response to warmer temperatures is strongly constrained by environmental variation, counteracting the positive effects of an early recovery process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2486.2004.00781.x
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