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  • 1
    Electronic Resource
    Electronic Resource
    Rhythmic release of dissolved free amino acids from partly synchronized Thalassiosira rotula under nearly natural conditions (1983)
    Springer
    Marine biology 74 (1983), S. 305-312 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In outdoor tanks enclosed monocultures of Thalassiosira rotula showed partly synchronized cell divisions during exponential growth. The changes in division activity showed a characteristic frequency, which also could be found for cell length (pervalvar axis) and assimilation rate as well as for concentration changes of dissolved free amino acids (DFAA) and ammonia. Excretion of DFAA occurred preferentially during periods of reduced cell division activity, when assimilation was at a higher level. The concentration of ammonia decreased during these periods. The rates per hour of these parameters showed significant multiple correlations. The release of six individual amino acids (ala, β-ala, gly, lys, orn and ser) seemed to be controlled by the physiological status of the diatoms. These amino acids amounted to a portion of about 70–80% of the total DFAA. Uptake and release rates of DFAA nitrogen and ammonia were in the same range with maxima of about 350 ng at nitrogen dm-3 h-1 and litre. These dynamics pointed to strong fluxes of organic bound nitrogen in marine micro-heterotrophs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403456
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Semi-automated methods for the determination of particulate phosphorus in the marine environment (1980)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 301 (1980), S. 14-16 
    Details
    ISSN: 1618-2650
    Keywords: Best. von Phosphor in Wasser ; Spektralphotometrie, AutoAnalyzer, Meerwasser, partikulärer Phosphor, Mo-Komplex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary After filtration of sea water through glass fiber filters, the filters with the residue are digested by heating with sulphuric acid and hydrogen peroxide. The following determination of phosphate is based on the formation of a phosphomolybdenum complex. It has been modified in such a way that the phosphorus content of the samples can be determined with a continuous-flow system with the TechniconAutoAnalyzer direct after digestion. Two methods are described for different sensitivities of 0.1–10μmol P · l−1.
    Notes: Zusammenfassung Der Rückstand bei Filtration von Meerwasser durch Glasfaserfilter wird mit Schwefelsäure und Wasserstoffperoxid aufgeschlossen. Die anschließende Phosphatbestimmung basiert auf der Bildung eines Phosphormolybdän-Komplexes. Sie wurde modifiziert, so daß der Phosphor-Gehalt der Proben sofort nach Aufschluß mit dem Durchflußsystem des Technicon-AutoAnalyzers bestimmt werden kann. Zwei Methoden mit unterschiedlicher Empfindlichkeit (von 0,1–10μmol P · l−1) werden beschrieben.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00481264
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    Paper (German National Licenses)
    Fulltext
  • 3
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    Unknown
    Release of dissolved free amino acids during a bloom of Thalassiosira rotula (1981)
    Institut für Meereskunde
    Details
    Publication Date: 2022-05-24
    Description: Three large plastic enclosures (3-4 m3) were anchored in the outer harbour of Helgoland (German Bight) and filled with natural seawater which was filtered free of algae. The enclosed water bodies were enriched with inorganic nutrients and inoculated with the diatom Thalassiosira rotula. During the growth of the algae diurnal changes in concentration of dissolved free amino acids (DFAA) occurred. The periodic concentration changes of individual amino acids with a low carbon to nitrogen ratio showed significant interrelationships with the partly synchronous devisions of the diatoms. From the exponential to the stationary phase the carbon to nitrogen ratio of DFAA shifted to higher values pointing at an adaptation of the organisms to the decreasing inorganic nitrogen source. During the bloom amino acids relatively rich in nitrogen were mainly excreted but by the end of the growth amino acids with a higher carbon content predominated. At phases of high photosynthetic activity the organisms probably reduced the high osmotic pressure by exudation of DFAA.
    Type: Article , NonPeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - without review
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