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1Author    Wolfgang Engelmann, Karl Simon, ChenJyh PhenRequires cookie*
 Title      
 Abstract    A circadian rhythm o f leaf movements o f Arabidopsis thaliana and its recording in continuous weak light with a video-computer system is described. 
  Reference    Z. Naturforsch. 47c, 925 (1992); received August 28/September 14 1992 
  Published    1992 
  Keywords    Circadian Rhythms, Cotyledons, Picture Analysis, Video Digitizing 
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 TEI-XML for    default:Reihe_C/47/ZNC-1992-47c-0925_n.pdf 
 Identifier    ZNC-1992-47c-0925_n 
 Volume    47 
2Author    Ursula Hamm, M. Aroli, K. Chandrashekaran, W. Olfgang EngelmannRequires cookie*
 Title    Temperature Sensitive Events between Photoreceptor and Circadian Clock?  
 Abstract    The phase shifting action of low temperature pulses of 6 °C and 2 h duration administered to the various phases of the D rosoph ila pseudoobscu ra circadian rhythm and the action of light pulses given 30 min after the beginning of these low temperature pulses have been investigated. The phase response curve obtained from experiments with light pulses during low temperature cannot be ex­ plained on the basis of a straightforward and sequential phase shifting of the oscillation by the various transitions in the pulses. The response curve, after the slight phase shifting action of the temperature pulses is corrected for, resembles the standard phase response curve 4 for light pulses (at 20 °C) in its wave form but n ot in its time course. Our curve is shifted in time in a manner that indicates that the light pulses accompanying the low temperature pulses arrived at phase points 1.5 h later than the actual phases at which they were given. We attribute this delay to a slowing down of the information that is apparently transmitted by a process that is temperature dependent. 
  Reference    (Z. Naturforsch. 30c, 240 [1975]; received November 22 1974) 
  Published    1975 
  Keywords    Circadian Rhythm, Photoreceptor, Temperature, D rosophila pseudoobscura 
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 TEI-XML for    default:Reihe_C/30/ZNC-1975-30c-0240.pdf 
 Identifier    ZNC-1975-30c-0240 
 Volume    30 
3Author    Karlfriedrich Hofmann, Martina Günderoth-Palmowski, Gottfried Wiedenmann, Wolfgang EngelmannRequires cookie*
 Title    Further Evidence for Period Lengthening Effect of L i+ on Circadian Rhythms  
 Abstract    The period length of the activity rhythm of the cockroach Leucophaea maderae is increased by a LiCl solution of 100 mol m—3 offered as drinking water by about 1%. 
  Reference    Z. Naturforsch. 33c, 231 (1978); received February 2. 1978 
  Published    1978 
  Keywords    Circadian Rhythm, Activity, Li, Leucophaea maderae, Mesocricetus auratus 
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 TEI-XML for    default:Reihe_C/33/ZNC-1978-33c-0231.pdf 
 Identifier    ZNC-1978-33c-0231 
 Volume    33 
4Author    Wolfram Lork, Til Kreuels, Wolfgang Martin, Klaus BrinkmannRequires cookie*
 Title    System Analysis of the Circadian Rhythm of Euglena gracilis, I. Linearities and Non-Linearities in the Response to Temperature Signals  
 Abstract    The approach of control theory is used to describe the structure of the circadian system of Euglena gracilis. As a first step we discriminate linear and non linear properties of the dynamics. The cellular motility as measured via long time records of sedimentation parameters in cultures is defined as the system output; sinusoidal temperature signals are used as input. By means of non stationary signal processing procedures we estimate gain and phase of the output signal. The problem of defining an appropiate gain of a cell suspension with an undefinite number of cells is solved by using the superimposition of two different input signals and by keeping one of them fixed as a reference signal. Linear properties are shown with a linear frequency transfer and with the validity of the superposition principle at least within distinct regions of amplitude and frequency. Non linear properties are the signal distortion, the restriction of linear amplification to a distinct range of input temperature and the ambiguity of phase coupling near the circadian eigenfrequency. The apparent lack of a limit of entrainment -an unexpected linear property — is explained by the masking effect of thermokinesis. A model is proposed describing the simultaneous control of motility by thermokinesis and the circadian system. On the base of that model further experiments are outlined. 
  Reference    Z. Naturforsch. 37c, 1240—1252 (1982); received June 15 1982 
  Published    1982 
  Keywords    Circadian Rhythm, Euglena, Motility, Oscillator, Temperature 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-1240.pdf 
 Identifier    ZNC-1982-37c-1240 
 Volume    37 
5Author    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 
6Author    GottfriedW. IedenmannRequires cookie*
 Title    Weak and Strong Phase Shifting in the Activity Rhythm of L eu co p h a ea m a d e r a e (Blaberidae) after Light Pulses of High Intensity  
 Abstract    In the running activity of the cockroach Leucophaea maderae a strong phase response curve is found when using high intensity light pulses (80 000 lx and about 12 hours duration). The phase response curve has an unsymmetric shape: delays are larger than advances. The phase jump lies about 2 hours after subjective midnight. 
  Reference    (Z. Naturforsch. 32c, 464 [1977]; received February 21 1977) 
  Published    1977 
  Keywords    Activity, Circadian Rhythm, Cockroach, Leucophaea, Light Pulse, Phase Response Curve 
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 TEI-XML for    default:Reihe_C/32/ZNC-1977-32c-0464_n.pdf 
 Identifier    ZNC-1977-32c-0464_n 
 Volume    32 
7Author    A. Johnsson, W. Engelmann, W. Klemke, AudTveito EkseRequires cookie*
 Title    Free-Running Human Circadian Rhythms in Svalbard  
 Abstract    The body temperature, activity-rest time, electrolytes of urine samples and mood was measured in two persons during a 19 day period under continuous light conditions in the arctic (vicinity of Ny Alesund, Svalbard-Spitsbergen). For temperature recording a new thermoprobe and a portable printer was used. Possible week Zeitgeber of the 24 hour day did not synchronize the circadian system, since circadian rhythms of about 26 hours were found. These results open up the pos­ sibility to study effects of drugs on the circadian system of humans under Svalbard conditions. In tro d u c tio n 
  Reference    Z. Naturforsch. 34c, 470 (1979); received March 13 1979 
  Published    1979 
  Keywords    Circadian Rhythms, Body Temperature, Activity, Urine Electrolytes, Humans, Svalbard-Spitsbergen 
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 TEI-XML for    default:Reihe_C/34/ZNC-1979-34c-0470.pdf 
 Identifier    ZNC-1979-34c-0470 
 Volume    34 
8Author    Ramanujam SubbarajRequires cookie*
 Title    Effect of Lithium Chloride on the Circadian Rhythm in the Flight Activity of the Microchiropteran Bat, Taphozous melanopogon  
 Abstract    We have performed experiments on the influence of Li+ offered through drinking water i) on the period length (t) of the rhythm in the flight activity o f bats under LL and ii) on phase angles during entrainment under LD cycles. Bats subject to entrainment exhibited no qualitative and quantitative change in ^ values after Li+ treatment. In contrast the ingestion of Li ions by bats under free-running conditions shortens the x of the bat rhythm by an amount that is a function of period length prior to ingestion, x is, thus homeostatically conserved in the face of Li administra­ tion in bats. 
  Reference    Z. Naturforsch. 36c, 1068—1071 (1981); received September 4 1981 
  Published    1981 
  Keywords    Circadian Rhythm, Flight Activity, Li+, Taphozous melanopogon, Homeostasis 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-1068.pdf 
 Identifier    ZNC-1981-36c-1068 
 Volume    36 
9Author    Ken GotoRequires cookie*
 Title    in Lemna  
 Abstract    Biochemical aspects o f circadian rhythms were studied using a long-day duckweed, Lem na gibba G 3 cultured in short day condition (9 h light at 3800 lux follow ed by 15 h darkness), which was transferred in continuous light (LL) at the end (LL 0) o f the last night period. With such a system I have previously reported a rhythm o f affinity for N A D + o f cytoplasm ic N A D -dependent glyceraldehyde 3-phosphate dehydrogenase (C yt-N A D -G P D) 180° out o f phase with that o f affinity for N A D P + o f chloroplastic N A D P -dependent G PD (C h l-N A D P -G P D) and that N A DP+ could increase in vitro the affinity for N A D P + o f C h l-N A D P -G PD . I report here that NA D P+ can decrease in vitro the affinity for N A D + o f C yt-N A D -G P D as well, and furthermore, that the in vivo level o f N A D P + oscillates in phase with the rhythm o f the affinity for N A D P + o f Chl-NADP-GPD. Moreover, I found the existence o f m irror-image circadian rhythms, o f com parable am pli­ tudes, o f in vivo levels o f N A D + + N A D H (total N A D) (with peaks, as the ones o f C yt-N A D -GPD. at LL 0 and 24) and o f N A D P + + N A D P H (total N A D P) (with peaks, as the ones o f Chl-NADP-G PD, at LL 12 and 36). Consequently, a circadian rhythm in the rate o f net in vivo production o f total N A D P (or N A D) m ight be expected 90° in advance o f that in the level o f total NADP (or N A D). Indeed. I found oscillations in the activities o f N A D kinase and o f NA DP phosphatase with peaks occurring, respectively, at LL 6 and at LL 18. Moreover, in vitro treatments with EGTA (a Ca2+-chelator), chlorprom azine and W 7 (both inhibitors o f cal­ modulin) were able to both inhibit N A D kinase from its highest level o f activity to its m inim al one and activate N A D P phosphatase from its lowest level o f activity to its maxim al one. I conclude, therefore, that the in vivo level o f C a2+-calm odulin could oscillate in phase with the rhythm o f N A D kinase activity and induce the mirror-image circadian rhythms o f activities o f NA D kinase and o f NA D P phosphatase. I propose that the control sequence among the several circadian rhythms I studied could start with changes in Ca2+-calm odulin, then proceed through oscillations in N A D kinase and N A D P phosphatase activities, leading to changes in N A D +, N A D P +, and N A D P H levels, which would themselves induce the C hl-N A D P -G PD and C yt-N A D -G P D rhythms. 
  Reference    Z. Naturforsch. 39c, 73 (1984); received June 16/Septem ber 19 1983 
  Published    1984 
  Keywords    Ca2+-Calmodulin, Circadian Rhythms, G lyceraldehyde 3-Phosphate Dehydrogenases (EC 12 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0073.pdf 
 Identifier    ZNC-1984-39c-0073 
 Volume    39 
10Author    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 
11Author    A. Kiinnea, E. Pistoriusb, K. Kloppstechc, E. De, G. RootdRequires cookie*
 Title    Circadian Synthesis of Light-Harvesting-Chlorophyll-Proteins in Euglena gracilis Is under Translational Control  
 Abstract    Two proteins with apparent molecular masses of 17 and 24 kD that are synthesized in a circadian manner in the phytoflagellate Euglena gracilis, were recognized as proteins belong­ ing to the family of light-harvesting-chlorophyll-proteins (LHCPs) of class 1(17 kD) and of class II (24 kD). Identification was achieved by N-terminal sequencing of the proteins iso­ lated from two-dimensional polyacrylamide gels and by detection with an anti-LHCP II se­ rum. While it was found that the total am ount of LHCPs remains almost constant, when Euglena is grown under diurnal conditions (12 h light and 12 h dark), we could show that the amount of newly synthesized 17 and 24 kD proteins varies about 20-fold with a maximum of synthesis in the light phase. In contrast, the analysis of the mRNA levels at different times revealed only minor differences in the stationary concentration of the LHCP specific mRNA, indicating that the control of LHCP synthesis is at the translational level. Principally, the same finding was obtained using inhibitors of transcription. Thus, it is concluded that the expression of LHCPs in Euglena gracilis in contrast to that of higher plants is primarily regulated at the translational level. 
  Reference    Z. Naturforsch. 53c, 1017—1026 (1998); received July 7/August 3 1998 
  Published    1998 
  Keywords    Euglena gracilis, Circadian Rhythm, Translational Control, Protein Synthesis, Light-Harvesting-Chlorophyll-Proteins 
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 TEI-XML for    default:Reihe_C/53/ZNC-1998-53c-1017.pdf 
 Identifier    ZNC-1998-53c-1017 
 Volume    53