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  • 1
    Electronic Resource
    Electronic Resource
    Transient state characteristics of adaptation to changes in light conditions for the cyanobacterium Oscillatoria agardhii (1986)
    Springer
    Archives of microbiology 145 (1986), S. 353-357 
    Details
    ISSN: 1432-072X
    Keywords: Transient state ; Light limitation ; Chlorophyll a ; Phycobiliproteins ; Cyanobacteria ; Photosynthesis ; Light-shade adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transitions in growth irradiance level from 92 to 7 μEm-2 s-1 and vice versa caused changes in the pigment contents and photosynthesis of Oscillatoria agardhii. The changes in chlorophyll a and C-phycocyanin contents during the transition from high to low irradiance (H→L) were reflected in photosynthetic parameters. In the L→H transition light utilization efficiencies of the cells changed faster than pigment contents. This appeared to be related to the lowering of light utilization efficiencies of photosynthesis. As a possible explanation it was hypothesized that excess photosynthate production led to feed back inhibition of photosynthesis. Time-scales of changes in the maximal rate of O2 evolution were discussed as changes in the number of reaction centers of photosystem II in relation to photosynthetic electron transport. Parameters that were subject to change during irradiance transitions obeyed first order kinetics, but hysteresis occurred when comparing H→L with L→H transients. Interpretation of first order kinetic analysis was discussed in terms of adaptive response vs changes in growth rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00470870
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  • 2
    Electronic Resource
    Electronic Resource
    Transient states of geosmin, pigments, carbohydrates and proteins in continuous cultures of Oscillatoria brevis induced by changes in nitrogen supply (1988)
    Springer
    Archives of microbiology 150 (1988), S. 333-337 
    Details
    ISSN: 1432-072X
    Keywords: Transient state ; Light limitation ; Nitrogen limitation ; Chlorophyll a ; β-Carotene ; Phycobiliproteins ; Geosmin ; Cyanobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transitions in the growth limiting factor from light (I) to nitrogen (N) and vice versa caused changes in geosmin production, protein and carbohydrate content, and the synthesis of pigments such as chlorophyll a (Chl a), phycobiliproteins (PBPs), and β-carotene of the cyanobacterium Oscillatoria brevis. Following I→N transition the first 150h, the decrease in protein content was compensated for by an increase of carbohydrates, and thereby, a constant biomass level was maintained in this period. Thereafter, biimass dropped to 15% of its initial level. A decrease in geosmin and pigment content was observed during transition from I→N-limited growth. However, geosmin increased relative to phytol (Chl a) and β-carotene which may indicate that a lowered demand for phytol and β-carotene during N-limited growth allows isoprenoid precursors to be directed to geosmin rather than to pigment synthesis. Synthesis of Chl a and β-carotene at the expense of geosmin was suggested for the observed start of increase in geosmin production only at the time that Chl a and β-carotene had reached their I-limited steady state. Transition from nitrogen to light limited growth caused an acceleration of metabolism shown by a rapid decrease in carbohydrate content accompanied by an increase in protein content. The growth rate of the organisms temporarily exceeded the dilution rate of the culture and the biomass level increased 6-fold. Due to the only modest changes in geosmin production (2-fold) compared to changes in biomass level (6-fold) during I-or N-limited growth, environmental factors seem to have limited effect on geosmin production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408303
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  • 3
    Electronic Resource
    Electronic Resource
    Regulation of growth and photosynthesis by Oscillatoria agardhii grown with a light/dark cycle (1985)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 31 (1985), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The cyanobacterium Oscillatoria agardhii was grown in turbidostat cultures with the light energy supply in either the continuous mode or in the pulsed mode (8/16 h light/dark (L/D) cycle). The light irradiance value used was sufficient to allow the maximal growth rate to be attained, when supplied continuously. Adaptation of O. agardhii to the L/D cycle was characterized by an increase in pigment content and photosynthetic performance, accompanied by a decrease in growth rate. This mode of adaptation resembled the adaptation of O. agardhii to continuous low light intensities. It is suggested that in this case the L/D cycle provokes this adaptation in order to allow the cells to accumulate carbohydrate rapidly during the light period. This was attributed to the storage of polyglucose, which served as a carbon and energy source for growth in the dark. The utilization of polyglucose in the dark was able to sustain the synthesis of all other cell components at the same rate as when cells were growing in the light. The growth yield in the dark, whilst metabolizing internally stored polyglucose, was 0.52 g cell C/g polyglucose C, or 0.62 g cell dry weight/g polyglucose. Although in the pulsed mode there is a 66% loss in light irradiance per 24 h when compared with a continuous light regime, the growth rate of the cyanobacteria grown in the pulsed mode was only 35% lower than the growth rate of a culture grown in continuous light. This can be explained by a high growth yield in the dark and by increased CO2 fixation rates in the light of cells grown in the pulsed mode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1985.tb01136.x
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  • 4
    Electronic Resource
    Electronic Resource
    Ammonia enhanced dark respiration in Chlorella vulgaris is related to collapse of a transmembrane pH gradient (1993)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 113 (1993), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Dark consumption of oxygen by Chlorella vulgaris was shown to be stimulated by increasing the external ammonium concentration. The ammonium effect was pH-dependent suggesting that an increased influx of free ammonia at higher pH values was cause to the effect. Breakdown of a transmembrane pH gradient between the cytoplasm and the interior of a cellular compartment was found to be related with enhanced oxygen consumption. Acid vacuoles are the most likely target for a collapse of the ΔpH since they form the only acid compartment where ammonia could accumulate as ammonium in dark adapted C. vulgaris cells. An alternative hypothesis involving the combined operation of a ATP-requiring proton extrusion pump and a Na+/H+ antiporter in the cytoplasmic membrane has been discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1993.tb06480.x
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  • 5
    Electronic Resource
    Electronic Resource
    Genome divergence in two Prochlorococcus ecotypes reflects oceanic niche differentiation (2003)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 424 (2003), S. 1042-1047 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The marine unicellular cyanobacterium Prochlorococcus is the smallest-known oxygen-evolving autotroph. It numerically dominates the phytoplankton in the tropical and subtropical oceans, and is responsible for a significant fraction of global photosynthesis. Here we compare the genomes of two ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature01947
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  • 6
    Electronic Resource
    Electronic Resource
    Regulation of cyanobacterial photosynthesis determined from variable fluorescence yields of photosystem II (1986)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 35 (1986), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The cyanobacteria Fremyella diplosiphon 7601 and Synechocystis 6701 were grown in continuous cultures with monochromatic red light (680 nm). The distribution of light energy over photosystem I and II was determined from changes in PS II fluorescence at 685 nm. In both organisms, wavelengths absorbed primarily by chlorophyll a caused the high fluorescent state of PS II (State 1), while wavelengths absorbed by the phycobilisome led to low PS II fluorescence (State 2). Superimposing continuous light 2 on the excitation light yielded State 2 fluorescence patterns for Synechocystis 6701, while F. diplosiphon 7601 showed fluorescence patterns similar to state 1 → 2 transitions and changes in fluorescence yield were related to the intensity of the background light. Some ecological implications of energy (re)distribution in cyanobacterial photosynthesis are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1986.tb01514.x
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  • 7
    Electronic Resource
    Electronic Resource
    The photosynthetic machinery in prochlorophytes: Structural properties and ecological significance (1994)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 13 (1994), S. 0 
    Details
    ISSN: 1574-6976
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract: The Prochlorophytes are a diverse group of photosynthetic prokaryotes which falls within the cyanobacterial lineage, yet lack phycobilisomes as light harvesting structures. Instead, the Prochlorophytes have a light-harvesting apparatus composed of the higher plant pigments chlorophylls a and b. This review discusses antenna structures, photosynthetic properties and evolutionary relationships among these bacteria, with focus on the role of photosynthesis in their natural habitat. Most of the available information is obtained from studies on Prochlorothrix, the model organism of this group in laboratory studies. Our analysis yields a consensus from studies on two Prochlorophytes, Prochloron and Prochlorothrix, as to how the thylakoid membrane is organized. Lack of laboratory studies on an abundant third Prochlorophyte, Prochlorococcus, does not (yet) allow to include this species in the consensus. Overall, we propose that the structure of the light-harvesting complexes from Prochlorophytes is very different from those of chloroplast systems, and is evolutionarily very ancient. The light-harvesting apparatus is considered to maintain a strong structural and functional association with Photosystem I in both Prochlorothrix and Prochloron. Photosystem It in Prochlorothrix differs from other photosynthetic systems in structural and functional properties of both donor and acceptor sides of its reaction center. A demonstrated capacity for Photosystem I-dependent anoxygenic photosynthesis in Prochlorothrix may indicate that there is an increased dependence on cyclic photophosphorylation in these organisms. A description of the natural habitats of the Prochlorophytes has been employed as a jumping board for speculation on the role of the photosynthetic apparatus in occupying, proliferating and surviving in their ecological niches. Prochlorophytes seem to thrive in stable environments of low light, sufficient nitrogen supply and possibly the presence of essential organic solutes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6976.1994.tb00059.x
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  • 8
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    Divergent responses of Atlantic coastal and oceanicSynechococcusto iron limitation (2015)
    National Academy of Sciences
    Details
    Publication Date: 2015-07-27
    Description: MarineSynechococcusare some of the most diverse and ubiquitous phytoplankton, and iron (Fe) is an essential micronutrient that limits productivity in many parts of the ocean. To investigate how coastal and oceanic AtlanticSynechococcusstrains acclimate to Fe availability, we compared the growth, photophysiology, and quantitative proteomics of twoSynechococcusstrains from different Fe regimes.Synechococcusstrain WH8102, from a region in the southern Sargasso Sea that receives substantial dust deposition, showed impaired growth and photophysiology as Fe declined, yet used few acclimation responses. Coastal WH8020, from the dynamic, seasonally variable New England shelf, displayed a multitiered, hierarchical cascade of acclimation responses with different Fe thresholds. The multitiered response included changes in Fe acquisition, storage, and photosynthetic proteins, substitution of flavodoxin for ferredoxin, and modified photophysiology, all while maintaining remarkably stable growth rates over a range of Fe concentrations. Modulation of two distinct ferric uptake regulator (Fur) proteins that coincided with the multitiered proteome response was found, implying the coastal strain has different regulatory threshold responses to low Fe availability. Low nitrogen (N) and phosphorus (P) availability in the open ocean may favor the loss of Fe response genes when Fe availability is consistent over time, whereas these genes are retained in dynamic environments where Fe availability fluctuates and N and P are more abundant.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 9
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    Phytoplankton–bacterial interactions mediate micronutrient colimitation at the coastal Antarctic sea ice edge (2015)
    National Academy of Sciences
    Details
    Publication Date: 2015-07-28
    Description: Southern Ocean primary productivity plays a key role in global ocean biogeochemistry and climate. At the Southern Ocean sea ice edge in coastal McMurdo Sound, we observed simultaneous cobalamin and iron limitation of surface water phytoplankton communities in late Austral summer. Cobalamin is produced only by bacteria and archaea, suggesting phytoplankton–bacterial interactions must play a role in this limitation. To characterize these interactions and investigate the molecular basis of multiple nutrient limitation, we examined transitions in global gene expression over short time scales, induced by shifts in micronutrient availability. Diatoms, the dominant primary producers, exhibited transcriptional patterns indicative of co-occurring iron and cobalamin deprivation. The major contributor to cobalamin biosynthesis gene expression was a gammaproteobacterial population, Oceanospirillaceae ASP10-02a. This group also contributed significantly to metagenomic cobalamin biosynthesis gene abundance throughout Southern Ocean surface waters. Oceanospirillaceae ASP10-02a displayed elevated expression of organic matter acquisition and cell surface attachment-related genes, consistent with a mutualistic relationship in which they are dependent on phytoplankton growth to fuel cobalamin production. Separate bacterial groups, including Methylophaga, appeared to rely on phytoplankton for carbon and energy sources, but displayed gene expression patterns consistent with iron and cobalamin deprivation. This suggests they also compete with phytoplankton and are important cobalamin consumers. Expression patterns of siderophore- related genes offer evidence for bacterial influences on iron availability as well. The nature and degree of this episodic colimitation appear to be mediated by a series of phytoplankton–bacterial interactions in both positive and negative feedback loops.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 10
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    Sources of aerosol nitrate to the Gulf of Aqaba: Evidence from δ15N and δ18O of nitrate and trace metal chemistry (2010)
    Elsevier
    Details
    Publication Date: 2010-06-01
    Print ISSN: 0304-4203
    Electronic ISSN: 1872-7581
    Topics: Geosciences
    Published by Elsevier
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