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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 145 (1986), S. 353-357 
    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
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  • 2
    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
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  • 3
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in The ISME Journal 6 (2012): 670–679, doi:10.1038/ismej.2011.128.
    Description: Akinetes are dormancy cells commonly found among filamentous cyanobacteria, many of which are toxic and/or nuisance, bloom-forming species. Development of akinetes from vegetative cells is a process that involves morphological and biochemical modifications. Here we applied a single cell approach to quantify genome and ribosome content of akinetes and vegetative cells in Aphanizomenon ovalisporum (Cyanobacteria). Vegetative cells of A. ovalisporum were naturally polyploid and contained on average 8 genome copies per cell. However, the chromosomal content of akinetes increased up to 450 copies, with an average value of 119 genome copies per akinete, 15 fold higher that in vegetative cells. Based on fluorescence in situ hybridization with a probe targeting 16S rRNA and detection with confocal laser scanning microscopy we conclude that ribosomes accumulated in akinetes to a higher level than that found in vegetative cells. We further present evidence that this massive accumulation of nucleic acids in akinetes is likely supported by phosphate supplied from inorganic polyphosphate bodies that were abundantly present in vegetative cells, but notably absent from akinetes. These results are interpreted in the context of cellular investments for proliferation following long term dormancy, as the high nucleic acid content would provide the basis for extended survival, rapid resumption of metabolic activity and cell division upon germination.
    Description: Supported by the Gruss Lipper Foundation research award (AS). This study was part of the Joint German-Israeli-Project (FKZ 02WT0985, WR803) funded by the German Ministry of Research and Technology (BMBF) and Israel Ministry of Science and Technology (MOST).
    Keywords: Akinetes ; Cyanobacteria ; Dormancy ; Fluorescence in situ hybridization ; Polyphosphate ; Polyploidy ; Laser microdissection microscopy
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: application/pdf
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  • 4
    Publication Date: 2022-05-26
    Description: © The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Microbiology 5 (2014): 359, doi:10.3389/fmicb.2014.00359.
    Description: Cyanobacteria thrive in every illuminated aquatic environment known, contributing at least 25% of primary productivity worldwide. Given their importance in carbon and nutrient cycles, cyanobacteria are essential geochemical agents that have shaped the composition of the Earth's crust, oceans and atmosphere for billions of years. The high diversity of cyanobacteria is reflected in the panoply of unique physiological adaptations across the phylum, including different strategies to optimize light harvesting or sustain nitrogen fixation, but also different lifestyles like psychrotrophy, and oligotrophy. Some cyanobacteria produce secondary metabolites of cryptic function, many of which are toxic to eukaryotes. Consequently, bloom-forming toxic cyanobacteria are global hazards that are of increasing concern in surface waters affected by anthropogenic nutrient loads and climate change.
    Keywords: Cyanobacteria ; HABs ; Prochlorococcus ; Synechococcus ; Nitrogen fixation
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
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