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'Euglena gracilis' in keywords Facet   Publication Year 1984  [X]
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1Author    RitaM. Fink, ErichF. ElstnerRequires cookie*
 Title    Comparison of Different Methods for the Determination of Phenylalanine Hydroxylase Activity in Rat Liver and Euglena gracilis  
 Abstract    Three different methods for the determination of phenylalanine hydroxylase activity have been compared: a) Differential photometric assay of the increase in tyrosine concentration in the presence of phenylalanine; b) Product separation by thin layer chromatography and scintillation counting of the [14C]tyrosine formed; c) HPLC separation and spectrofluorometric quantification of derivatized amino acids. A comparison of the activities of phenylalanine hydroxylase in rat liver and Euglena gracilis clearly showed that only rat liver contains this enzymic activity as shown by methods b) and c) although pseudo-activity of Euglena gracilis preparations was found during the spectrophoto-metric test a). The HPLC method proved to be the fastest, most reliable and convenient method for direct tyrosine determination and thus for measuring phenylalanine hydroxylase activity. 
  Reference    Z. Naturforsch. 39c, 728—733 (1984); received January 27/April 14 1984 
  Published    1984 
  Keywords    Phenylalanine Hydroxylase, Rat Liver, Euglena gracilis, Tyrosine Determination 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0728.pdf 
 Identifier    ZNC-1984-39c-0728 
 Volume    39 
2Author    T. Kreuels, R. Joerres, W. M. Artin, K. BrinkmannRequires cookie*
 Title    System Analysis of the Circadian Rhythm of Euglena gracilis, II: Masking Effects and Mutual Interactions of Light and Temperature Responses  
 Abstract    Motility o f Euglena gracilis shows free running circadian rhythms. The circadian system is sensitive to light and temperature signals, but it is always m asked by direct responses o f m otility to light (photokinesis) and temperature (therm okinesis). By means o f a com partim ental m odel which defines the interrelations between the pathways o f therm okinesis, photokinesis and the circadian system a unifying view o f effects o f temperature and light input signals is outlined. According to the model, and using double sine input signals the dynam ics o f thermokinesis is described by a differential am plifier with constant gain. Although thermokinesis heavily masks circadian responses to tem perature signals, the lim ited range o f circadian entrainment is indirectly dem onstrated by a lim ited reappearance o f free running circadian oscillations after stopping the tem perature program. Free running circadian oscillations do reappear only after pretreatment with tem perature periods near the circadian eigenperiod. A white mutant lacking photosynthesis is used to investigate the role o f photosynthesis in the signal processing. Although light synchronizes the circadian rhythms o f the white mutant if applied as single input, it does not affect the m otility if applied together with temperature inputs near the circadian eigenperiod. These results indicate frequency dependent m utual interactions between the model compartments. 
  Reference    Z. Naturforsch. 39c, 801—8 (1984); received February 2 2 /April 27 1984 
  Published    1984 
  Keywords    Circadian Rhythm, System Analysis, Euglena gracilis, Masking Temperature Responses 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0801.pdf 
 Identifier    ZNC-1984-39c-0801 
 Volume    39