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  • nitrogen concentration  (3)
  • CO2  (1)
  • Cucumaria miniata  (1)
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Erscheinungszeitraum
  • 1
    ISSN: 1573-5176
    Schlagwort(e): Cyanobacterium ; Spirulina platensis ; Arthrospira ; CO2 ; organic carbon ; nitrogen ; photosynthesis ; batch culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The consequences of the addition of CO2 (1%) in cultures of S. platensis are examined in terms of biomass yield, cell composition and external medium composition. CO2 enrichment was tested under nitrogen saturating and nitrogen limiting conditions. Increasing CO2 levels did not cause any change in maximum growth rate while it decreased maximum biomass yield. Protein and pigments were decreased and carbohydrate increased by high CO2, but the capability to store carbohydrates was saturated. C:N ratio remained unchanged while organic carbon released to the external medium was enhanced, suggesting that organic carbon release in S. platensis is an efficient mechanism for the maintenance of the metabolic integrity, balancing the cell C:N ratio in response to environmental CO2 changes. CO2 affected the pigment content: Phycocyanin, chlorophyll and carotenoids were reduced in around 50%, but the photosynthetic parameters were slightly changed. We propose that in S. platensis CO2 could act promoting degradation of pigments synthetised in excess in normal CO2 conditions, that are not necessary for light harvesting. Nitrogen assimilation was significantly not affected by CO2, and it is proposed that the inability to stimulate N assimilation by CO2 enrichment determined the lack of response in maximum growth rate.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Journal of applied phycology 3 (1991), S. 319-327 
    ISSN: 1573-5176
    Schlagwort(e): Dunaliella viridis ; growth ; salinity ; temperature ; nitrogen concentration ; batch culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The growth of a strain ofD. viridis has been studied in batch culture under different combinations of temperature, salinity and nitrogen concentrations. Changes in these variables have a significant effect on cell division, biomass production, cell volume and pigment yield. This strain grows optimally at 1 M NaCl and 30 °C. Increasing salinity up to 4 M NaCl leads to a significant decrease of cell division rate and maximal population; growth at lower temperature decreases the rate of division of the cells but increases maximal cell density. Pigment yield decreases with increasing salinity and increases with increasing temperature. Nitrogen concentration has a large effect on total cell biomass and pigment production, but not on cell division rate. Saturation of growth occurs at 5 mM NO 3 − ; higher concentration (e.g. 10 mM) leads to a decrease of maximal cell density and photosynthetic pigment content.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Journal of applied phycology 2 (1990), S. 309-317 
    ISSN: 1573-5176
    Schlagwort(e): Dunaliella viridis ; net photosynthesis ; temperature ; nitrogen concentration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The photosynthetic behaviour ofDunaliella viridis has been studied under a combination of three variables: irradiance (0–900 μmol m−2 s−1), temperature (15, 23, 31, 38, 42 °C) and nitrogen concentration (0.05, 0.5, 1.5, 5, 10 mM NO 3 - ) at a salinity of 2 M NaCl. The highest rates of photosynthesis have been found at 31 °C and a nitrate concentration of 10 mM. There exists a synergistic effect between temperature and nitrogen availability on the photosynthesis ofD. viridis; under nitrogen deficiency oxygen evolution is low, even null at high temperature. The interaction between these two variables of control occurs in a multiplicative way. There is also a general increase in photosynthetic pigments following the increase in nitrogen concentration in the culture medium. The normalization of net photosynthesis data in relation to chlorophylla shows that nitrogen concentration makes an indirect control of the photosynthetic rate ofD. viridis through the variation of pigment concentration. The study of the photosynthetic parameters shows that the slope (α) of the curves of photosynthesis and the light-saturated photosynthesis (Pmax) are controlled by more than one variable, including temperature and nitrogen availability.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Journal of applied phycology 3 (1991), S. 319-327 
    ISSN: 1573-5176
    Schlagwort(e): Dunaliella viridis ; growth ; salinity ; temperature ; nitrogen concentration ; batch culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The growth of a strain ofD. viridis has been studied in batch culture under different combinations of temperature, salinity and nitrogen concentrations. Changes in these variables have a significant effect on cell division, biomass production, cell volume and pigment yield. This strain grows optimally at 1 M NaCl and 30 °C. Increasing salinity up to 4 M NaCl leads to a significant decrease of cell division rate and maximal population; growth at lower temperature decreases the rate of division of the cells but increases maximal cell density. Pigment yield decreases with increasing salinity and increases with increasing temperature. Nitrogen concentration has a large effect on total cell biomass and pigment production, but not on cell division rate. Saturation of growth occurs at 5 mM NO 3 − ; higher concentration (e.g. 10 mM) leads to a decrease of maximal cell density and photosynthetic pigment content.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 0947-3440
    Schlagwort(e): Carbohydrates ; Cucumaria japonica ; Cucumaria miniata ; Sea cucumbers ; Cucumariosides ; Triterpene glycosides ; Antitumor activity ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: New cytotoxic triterpene oligoglycoside disulfates, cucumariosides A3 (1) and A6-2 (2), have been isolated from the sea cucumber Cucumaria japonica. The trisulfated cucumarioside A7-3 (4) was found to be the major component in the glycoside fraction of Cucumaria miniata. The structures were assigned on the basis of extensive spectral data (NMR and MS), selective solvolysis of desulfated derivative 3 and other chemical evidence. The presence or absence of a carbonyl group at C-16 of the aglycone and of sulfate groups at C-6 of the glucose and 3-O-methylglucose units are interpreted in terms of the functional evolution of sea cucumbers in order to improve their defensive system. Both (1) and (2) are cytotoxic in vitro at IC50 = 1 μg/ml against a selection of five human and mice tumoral cell lines.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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