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41.
Fluence rate-response curves were determined for the inhibition of hypocotyl growth in 54 h old dark-grownSinapis alba L. seedlings by continuous or hourly 5 min red light irradiation (24 h). In both cases a fluence rate-dependence was observed. More than 90% of the continuous light effect could be substituted for by hourly light pulses if the total fluence of the two different light regimes was the same. Measurements of the far red absorbing form of phytochrome ([P
fr]) and [P
fr]/[P tot] (total phytochrome) showed a strong fluence rate-dependence under continuous and pulsed light which partially paralleled the fluence rate-response curves for the inhibition of the hypocotyl growth.Abbreviations R
red
- HIR
high irradiance response
-
P
rfr
phytochrome in its red, far-red absorbing form
- [P
tot]=[P
r]+[P
fr]
=k
1/(k
1+k
2): photoequilibrium of phytochrome at wavelength , wherebyk
1,2 rate constants ofP
rP
fr,P
frP
r photoconversion
-
[P
fr]/[P
tot] 相似文献
42.
When a walking fly approaches a stationary object two types of body movements are distinguishable. Type I body movements are characterized by low frequencies (0.4–1.3 Hz) and large amplitudes (28–65°). Superimposed on these movements are type II body movements which are characterized by high frequencies (7.3–10.6 Hz) and small amplitudes (5.9–8.2°) (Figs. 3–6; Table 1). Type II movements occur no matter whether the fly is fixating a pattern or orientating itself in homogeneous surroundings without any pattern. In contrast, only 72% of the flies with immobilized heads and 62% of the flies with movable heads make type I body movements. The amplitude of type I and type II body movements increases slightly after immobilization of the head. Binocular as well as monocular pattern projection occurs for the whole walking trajectory (Fig. 7–9). Monocular pattern projection seems to be more frequent in flies with immobilized heads than in those with movable heads. The degree of pattern fluctuations in the visual field of the flies increases slightly along the walking trajectory. Near the starting point in the centre of the arena it amounts to 5–7°, while at the end of the walking trajectory it amounts to 8–10° (Table 2). The following conclusions and hypothesis can be drawn from these experiments. 1. The graph BT for the direction of the fly's logitudinal axis can be approximated by the first derivative of the walking trajectory WT, that means, dWT(x)/dxBT(x) (Fig. 11). 2. The amplitudes of type II body movements are caused by the alternating movements of the legs during forward motion, while type I body movements are classified as exploring movements. During evolution of visually guided behaviour it is possible that blowflies have adapted their elementary movement detector system to type II body movements. 3. The types of pattern projection into the visual field of the fly while approaching an object can be explained by a simple neuronal network characterized by either inhibitory and/or excitatory influences of the visually activated neurones on the motor neurones generating the propulsive forces, that means the forward motion. In addition it is postulated that the large frontal and antero-lateral receptive fields of these neurones are not coupled with the motor centres on the same side of the body (Fig. 12). 相似文献
43.
Eberhard Hantge 《Journal of Ornithology》1980,121(2):200-207
Zusammenfassung Die beobachteten europäischen Greifvögel weisen bei Jagdflügen Erfolgsquoten von 5–11% auf. Lediglich der Fischadler scheint erfolgreicher zu sein.Etwa 2/3 aller Flüge des Sperbers und rund 1/3 des Habichtterzels werden nach Falkenart aus hoher Luft ausgeführt.Der Wanderfalk ist bei der Jagd auf Finken und Tauben in etwa gleich erfolgreich.Alle näher untersuchten Greifvögel benötigen bei gutem Beuteangebot zur Deckung des Eigenbedarfes rund 3 Stunden täglich, unabhängig vom Jagderfolg, mittlerem Beutegewicht und Zahl der pro Zeiteinheit ausgeführten Jagden.Zur Aufzucht von Jungen ist ein hoher Anteil von unerfahrenen Jungen unter den Beutetieren erforderlich.In nahrungsarmen Revieren pflanzt sich der Habicht über mehrere Jahre hinweg nicht fort.Es wird diskutiert, inwieweit eine passive Auslese durch Greifvögel stattfindet.
Observations on the efficiency of hunting in some birds of prey
Summary The efficiency of some European birds of prey (sparrowhawk, goshawk, hobby and peregrine) in making their kills amounts 5–11%.About 2/3 of all hunting flights of the sparrowhawk and 1/3 of the goshawk's had been observed in the manner similar to the peregrine.The peregrine has no more success in hunting finches than in hunting doves.The investigated birds of prey have to spent 3 hours per day in hunting their daily food requirement, if there is a high prey population.In this aspect the killing success, the average weight of prey and numbers of hunting flights per 3 hours are of no importance.For rearing broods a high population of unexperienced young animals (doves, jays, rabbits etc.) is necessary.The goshawk will not rear young for years, if there is no high population of prey.相似文献
44.
Gerhard Kopperschläger Elke Usbeck Eberhard Hofmann 《Biochemical and biophysical research communications》1976,71(1):371-378
Intracellular cross-linking of yeast phosphofructokinase with a series of diimidoesters of different chain length resulted in the appearance of tetramers as largest cross-linked product of the enzyme subunits. The native enzyme is evidently composed of eight subunits being arranged in two tetramers α4β4. In the tetramers the monomers are probably assembled in tetrahedral geometry. 相似文献
45.
Summary This report describes the results from cultured lymphocytes studied at metaphase, anaphase, and interphase from an individual with a ring chromosome 4. A ring was present in 90.1% of metaphases. Special attention was directed towards the occurrence of derivative chromosomal structures, such as partially duplicated and triplicated rings, tricentric rings, chains of 3 interlocked rings, rod-shaped chromosomes, pulverized rings, and others.The clinical features of the individual (small stature and impaired mental development, hypoplastic thumbs, ptosis palpebrae hypoplastic external male genitalia, abnormal dermatoglyphic pattern) did not conform to a specific phenotype.
This work was supported in part by grants from the Deutsche Forschungsgemeinschaft and is part of a thesis by R.N. for a medical doctorate. 相似文献
Zusammenfassung Die Lymphocyten eines Patienten mit Ringchromosom 4 wurden in der Meta-, Ana-und Interphase beobachtet. 90,1% der Metaphasen wiesen einen Ring auf. Besondere Aufmerksamkeit wurde abnormen, aus dem Ring entstandenen Chromosomen zugewandt. Es fanden sich u. a.: partielle Doppel-und Dreifachringe, Ringe mit 3 Zentromeren, Ringe aus 3 miteinander verketteten Ringen, stabförmige Chromosomen und pulverisierte Ringe.Die Symptome des Patienten (Minderwuchs, Schwachsinn, Hypoplasie der Daumen, Ptosis palpebrae, Hypoplasie des äußeren genitale, abnorme Dermatoglyphen) waren zum größten Teil unspezifish.
This work was supported in part by grants from the Deutsche Forschungsgemeinschaft and is part of a thesis by R.N. for a medical doctorate. 相似文献
46.
Johanna Blomqvist Thomas Eberhard Johan Schnürer Volkmar Passoth 《Applied microbiology and biotechnology》2010,87(4):1487-1497
The influence of pH, temperature and carbon source (glucose and maltose) on growth rate and ethanol yield of Dekkera bruxellensis was investigated using a full-factorial design. Growth rate and ethanol yield were lower on maltose than on glucose. In controlled
oxygen-limited batch cultivations, the ethanol yield of the different combinations varied from 0.42 to 0.45 g (g glucose)−1 and growth rates varied from 0.037 to 0.050 h−1. The effect of temperature on growth rate and ethanol yield was negligible. It was not possible to model neither growth rate
nor ethanol yield from the full-factorial design, as only marginal differences were observed in the conditions tested. When
comparing three D. bruxellensis strains and two industrial isolates of Saccharomyces cerevisiae, S. cerevisiae grew five times faster, but the ethanol yields were 0–13% lower. The glycerol yields of S. cerevisiae strains were up to six-fold higher compared to D. bruxellensis, and the biomass yields reached only 72–84% of D. bruxellensis. Our results demonstrate that D. bruxellensis is robust to large changes in pH and temperature and may have a more energy-efficient metabolism under oxygen limitation
than S. cerevisiae. 相似文献
47.
48.
Calcium binding to fluorescent calcium indicators: calcium green, calcium orange and calcium crimson 总被引:4,自引:0,他引:4
The recently introduced fluorescent calcium sensitive indicators calcium green, calcium orange and calcium crimson suggest important improvements and advantages to detect small calcium transients at low indicator concentrations. Thermodynamic dissociation constants and dissociation rate constants of calcium green, calcium orange and calcium crimson were measured by use of fluorescence titration and stopped flow fluorescence, respectively. Calcium binding to the indicators conforms to a 1:1 calcium:indicator complex although at high concentrations of calcium the fluorescence properties deviate somewhat from the behaviour predicted by the simple model. Dissociation of the calcium-indicator complex was found to be monoexponential under all conditions examined. The affinity for calcium of the three indicators generally increases with raising temperatures (Kd at 11.5 degrees C and 39.7 degrees C (nM): 261, 180 for calcium green; 527, 323 for calcium orange; 261, 204 for calcium crimson) and pH (Kd at pH 6.42 and 7.40 (nM): 314, 226 for calcium green; 562, 457 for calcium orange; 571, 269 for calcium crimson). The changes of the thermodynamic dissociation constant are mainly caused by changes of the association rate constant. The temperature dependence of calcium binding to the indicators revealed that this process is entropically favoured at ambient temperature. 相似文献
49.
50.
Eberhard Schnepf 《Protoplasma》1961,54(2):310-313
Ohne ZusammenfassungIch danke Herrn Prof. Dr. P. Sitte für die Überlassung der Korrekturbögen seiner Arbeit und einiger Aufnahmen sowie seine Hinweise, ferner der Deutschen Forschungsgemeinschaft für ihre Unterstützung. 相似文献