| | 2 | Author
| Ursula Hamm, M. Aroli, K. Chandrashekaran, W. Olfgang Engelmann | Requires 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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| default:Reihe_C/30/ZNC-1975-30c-0240.pdf | | | | Identifier
| ZNC-1975-30c-0240 | | | | Volume
| 30 | |
| 3 | Author
| Wolfram Lork, Til Kreuels, Wolfgang Martin, Klaus Brinkmann | Requires 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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| default:Reihe_C/37/ZNC-1982-37c-1240.pdf | | | | Identifier
| ZNC-1982-37c-1240 | | | | Volume
| 37 | |
| 4 | Author
| C. J. Soeder, E. Hegewald, E. Fiolitakis, J.U G Robbelaar | Requires cookie* | | | Title
| Temperature Dependence of Population Growth in a Green Microalga: Thermodynamic Characteristics of Growth Intensity and the Influence of Cell Concentration | | | | Abstract
| Growth intensity o f the green alga, Scenedesmus obliquus, was measured in autotrophic cultures, diluted once daily, between 20 and 30 °C in a light-dark cycle o f 16 : 8 h at initial optical densities between 0.02 and 1.2. Arrhenius analyses o f the results showed linear relationships be tween growth intensity and temperature below the temperature optimum. The temperature effects on growth, activation energy, deactivation energy and normalized Q i0 values were signifi cantly influenced by the amount o f available light energy per unit biomass. The temperature dependence o f nutrient-lim ited growth was not considered. | | | |
Reference
| Z. Naturforsch. 40c, 227—233 (1985); received Decem ber 5 1984 | | | |
Published
| 1985 | | | |
Keywords
| M icroalgae, Growth, Temperature, Light, Thermodynamics | | | |
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| default:Reihe_C/40/ZNC-1985-40c-0227.pdf | | | | Identifier
| ZNC-1985-40c-0227 | | | | Volume
| 40 | |
| 5 | Author
| JukkaP. Juutilainen | Requires cookie* | | | Title
| Effects of Low Frequency Magnetic Fields on Chick Embryos. Dependence on Incubation Temperature and Storage of the Eggs | | | | Abstract
| Chick embryos were exposed to sinusoidally oscillating 100 Hz magnetic fields during their first two days of development. The magnetic field strength was 1 A/m. Incubation temperatures of 36.3, 37.0, 38.0 and 38.5 °C were used and the duration of the storage of the eggs before incuba tion was varied from 1 hour to 4 days. After the incubation, the embryos were examined for abnormalities. When the temperature was 36.3 or 37.0 °C and the eggs were stored for one day or less, the effect of the magnetic field was statistically significant. In these conditions, the percent age of abnormal control embryos was low, 8% in 36.3 °C and 5% in 37.0 °C. In the exposed groups the corresponding percentages were 23% (36.3 °C) and 25% (37.0 °C). However, higher temperature and storage of the eggs for 3 to 4 days increased the percentage of abnormal embryos in both the exposed and control groups. The difference between the exposed and control embryos was not significant in these conditions. The results demonstrate the importance of the handling of the eggs in this kind of experiments. | | | |
Reference
| Z. Naturforsch. 41c, 1111 (1986); received May 16 1986 | | | |
Published
| 1986 | | | |
Keywords
| ELF Magnetic Fields, Chick Embryo, Teratology, Temperature | | | |
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| default:Reihe_C/41/ZNC-1986-41c-1111.pdf | | | | Identifier
| ZNC-1986-41c-1111 | | | | Volume
| 41 | |
| 6 | Author
| M. O. Iio, A. M. Okonkwo3, M. Bamideleb | Requires cookie* | | | Title
| Factors Affecting Growth of Sulfate-Reduc- ing Bacteria Isolated from Tropical Soil | | | | Abstract
| Sulfate-reducing bacteria (S R B) were isolated from soils around corroded pipelines and tanks. High num bers of the organisms occurred in areas closest to the corroded tanks and pipelines. Morphological types cor responding to rod, spirilloid, vibriod and coccoid were encountered. All the organisms utilized lactate as carbon and energy source. None could grow at temperatures higher than 40 °C. All the isolates grew at 1% (w/v) NaCl while none could grow at 8% (w/v) NaCl. All the isolates grew at pH 7 .0 -7 .5 . Growth was not recorded at pH below 5.5 and above 8.0. These factors may be useful in manipulating tropical soil environments to re duce activities of SR B in corrosion of pipelines and tanks. | | | |
Reference
| Z. Naturforsch. 54c, 613 (1999); received July 1/December 10 1998 | | | |
Published
| 1999 | | | |
Keywords
| Sulfate-Reducing Bacteria, Lactate, pH, Temperature, Sodium Chloride | | | |
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| default:Reihe_C/54/ZNC-1999-54c-0613_n.pdf | | | | Identifier
| ZNC-1999-54c-0613_n | | | | Volume
| 54 | |
| 7 | Author
| Jürgen Van Der Bosch, Ilse Sommer, Heinz Maier, Willy Rahmig | Requires cookie* | | | Title
| Density-Dependent Growth Adaptation Kinetics in 3T 3 Cell Populations Following Sudden [Ca2+] and Temperature Changes. A Comparison with SV40-3T3 Cells | | | | Abstract
| Lowered extracellular [Ca2+ ] causes low growth rates and low stationary cell densities in 3T3 cell cultures as compared to physiological [Ca2+ ]. Under otherwise constant conditions the extra cellular [Ca2+ ] determines a stable stationary cell density, which can be readied by increase of net cell number or decrease of net cell number, depending on cell density at the time of [Ca2+ ] adjustment. SV40-3T3 cells do not show this [Ca2+] dependency. At 39 °C 3T3 and SV40-3T3 cell populations show an increased growth rate at low cell densities as compared to cell popula tions at 35 °C. Approaching the stationary density the growth rate of both cell sorts is reduced faster at 39 °C than at 35 °C, leading to lower stationary cell densities at 39 °C than at 35 °C. A temperature change from 39 °C to 35 °C or in the opposite direction can affect the stationary cell density of 3T3 cell populations only if applied before reduction of growth rate by density-dependent growth-inhibiting principles has taken place. | | | |
Reference
| Z. Naturforsch. 34c, 279 (1979); received December 19 1978 | | | |
Published
| 1979 | | | |
Keywords
| Ca2+, Temperature, Growth Control, 3T3 Cell, SV40-3T3 Cell | | | |
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| | | | | TEI-XML for
| default:Reihe_C/34/ZNC-1979-34c-0279.pdf | | | | Identifier
| ZNC-1979-34c-0279 | | | | Volume
| 34 | |
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