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'Chlorella' in keywords Facet   Publication Year 1984  [X]
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1984[X]
1Author    Margarete Hoffmans-Hohn, W. Olfgang, M. Artin, Klaus BrinkmRequires cookie*
 Title    Multiple Periodicities in the Circadian System of Unicellular Algae  
 Abstract    Three periodicities in the circadian range are observed when m easuring circadian parameters of unicellular organisms in long running experim ents (m ore than 15 days). This is dem onstrated for different organisms (Chlamydomonas, Euglena, C hlorella) and different parameters (auto­ kinesis, extracellular pH, C 0 2-and 0 2-partial pressure). H aving excluded analytical and experimental artefacts {i.e. filter leakage and subpopulation effects), the m ultiple periodicities have to be interpreted in a physiological m odel. The three p eriod icities always exhibit two common features: The locations o f the side peaks are sym m etrical to the m iddle peak and their energy contribution is always the same. W e therefore favour the m odel o f m ultiplicative coupling between the circadian oscillator and a low frequency oscillator m odulating the am plitude o f the circadian rhythm. Since the low frequency rhythm is not correlated to any exogenously running periodicity o f the experim ental surroundings, it is considered as generated by an endogenous oscillator. This shows the existence o f different biological long tim e oscillators in one single cell and contradicts the so-called m aster-clock hypothesis stating that one cell has only one clock related oscillator. 
  Reference    Z. Naturforsch. 39c, 791—8 (1984); received D ecem ber 5 1983/M arch 17 1984 
  Published    1984 
  Keywords    Circadian Rhythm, pH-Rhythm, Chlamydomonas, Euglena, Chlorella 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0791.pdf 
 Identifier    ZNC-1984-39c-0791 
 Volume    39 
2Author    Ahlert SchmidtRequires cookie*
 Title    Occurrence of Mercaptopyruvate Sulfotransferase Activity in Photosynthetic Organisms  
 Abstract    Mercaptopyruvate sulfotransferase activity catalyzes the formation o f pyruvate from mercapto­ pyruvate in the presence o f suitable reagents as acceptor. It was detected in Lemna minor, Pisum sativum, Spinacia oleracea, Chlorella fusca, Synechococcus 6301, and Rhodopseudomonas palustris. Best activity was detected using dithioerythritol as a thiol reagent; good activity was obtained using mercaptoethanol, glutathione, mercaptopyruvate or sulfite as acceptor. The pH-optimum for the Chlorella mercaptopyruvate sulfotransferase was found around 9; the apparent Km for mercaptopyruvate was determined to 2 m M and for dithioerythritol for 5 m M using crude Chlorella extracts. The role of this enzyme is discussed in relation to cysteine catabolism by photosynthetic organisms. 
  Reference    Z. Naturforsch. 39c, 916—921 (1984); received April 6 1984 
  Published    1984 
  Keywords    Pyruvate, Mercaptopyruvate, Lemna, Spinacia, Pisum, Chlorella, Synechococcus, Rhodopseudomonas 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0916.pdf 
 Identifier    ZNC-1984-39c-0916 
 Volume    39