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1.
Helmut Grimm 《Behavioural processes》1981,6(1):63-84
The endemic Anatolian cyprinodonts Aphanius chantrei, A. (Kosswigichtys) asquamatus, and A. anatoliae show definite interspecific differences in their territorial and sexual behaviour under laboratory conditions. Intraspecific differences were found in the nine populations of A. anatoliae investigated.A. chantrei and Kosswigichthys show almost the same territorial behaviour. In A. anatoliae territoriality is found in three populations; the remaining six populations show no territoriality.The sexual behaviour consists of visual display elements and of elements which enable the fish to keep close contact without actually touching each other. The sequence of elements can be variable. Only two populations of A. anatoliae have retained display elements; the remaining seven populations have lost all of them.A correlation is discussed between biotope conditions and sexual behaviour. Display and territorial behaviour may have become superfluous in extreme, sulphate-containing habitats, where a lack of flora has led to a lack of spawning sites. Under changing breeding conditions the newly evolved element with fish staying close together (male underneath the female) may have replaced the former display elements. 相似文献
2.
Using comparative ion-exchange chromatography on Dowex 1X4, the product of dephosphorylation of fructose 2,6-bisphosphate with purified yeast fructose-2,6-bisphosphate 6-phosphohydrolase, was shown to be identical to the furanose form of fructose 2-phosphate prepared by chemical synthesis according to Pontis and Fischer [Biochem. J. 89, 452-459 (1963)]. As expected for the furanose form of fructose 2-phosphate, the enzymatically formed product consumes 1 mol periodate/mol fructose 2-phosphate, whereas the chemically synthesized pyranose form consumes 2 mol periodate/mol. In addition, it is shown that the enzymatic product behaves identically to the furanose, not the pyranose, form of fructose 2-phosphate in hydrolysis of the ester bond at pH 4 and 37 degrees C, as described previously for the chemically synthesized compounds [Pontis and Fischer (1963) vide supra]. 相似文献
3.
We have investigated the mechanism by which heat shock conditions lead to a reversible accumulation of trehalose in growing yeast. When cells of S. cerevisiae M1 growing exponentially at 30 degrees C were shifted to 45 degrees C for 20 min, or to 39 degrees C for 40 min, the concentration of trehalose increased by about 25-fold; an effect reversed upon lowering the temperature to 30 degrees C. This was compared to the more than 50-fold rise in trehalose levels obtained upon transition from the exponential to the stationary growth phase. Whereas the latter was paralleled by a 12-fold increase in the activity of trehalose-6-phosphate synthase, no significant change in the activities of trehalose-synthesizing and -degrading enzymes was measured under heat shock conditions. Accordingly, cycloheximide did not prevent the heat-induced accumulation of trehalose. However, the concentrations of the substrates for trehalose-6-phosphate synthase, i.e. glucose-6-phosphate and UDP-glucose, were found to rise during heat shock by about 5-10-fold. Since the elevated levels of both sugars are still well below the Km-values determined for trehalose-6-phosphate synthase in vitro, they are likely to contribute to the increase in trehalose under heat shock conditions. A similar increase in the steady-state levels was obtained for other intermediates of the glycolytic pathway between glucose and triosephosphate, including ATP. This suggests that temperature-dependent changes in the kinetic parameters of glycolytic enzymes vary in steady-state levels of intermediates of sugar metabolism, including an increase of those that are required for trehalose synthesis. Trehalose, glucose-6-phosphate, UDP-glucose, and ATP, were all found to increase during the 40 min heat treatment at 39 degrees C. Since this also occurs in a mutant lacking the heat shock-induced protein HSP104 (delta hsp104), this protein cannot be involved in the accumulation of trehalose under these heat shock conditions. However, mutant delta hsp104, in contrast to the parental wild-type, was sensitive towards a 20 min incubation at 50 degrees C. Since this mutant also accumulated normal levels of trehalose, we conclude that HSP104 function, and not towards a 20 min incubation at 50 degrees C. Since this mutant also accumulated normal levels of trehalose, we conclude that HSP104 function, and not the accumulation of trehalose, protects S. cerevisiae from the damage caused by a 50 degrees C treatment. 相似文献
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The orientation of the superior articular processes with regard to the upper end-plate of the sacrum does not depend on the inclination of the sacrum. This assertion can be made by interpreting certain angles already described in literature and may be confirmed by a research following strict biomechanic principles: The orientation of the articular processes is put in relation to the direction of the forward shear brought upon by the Vth lumbar vertebra and caused by the inclination of the sacrum. This is achieved by measuring the angle between the articular facet and a plane normal to the mentioned forward shear. The result is that the size of this angle does not at all depend on the degree of the inclination of the sacrum. 相似文献
7.
Helmut Segner Roland Marthaler Michael Linnenbach 《Environmental Biology of Fishes》1988,21(2):153-159
Synopsis Young (7–10 days after hatching) brown trout (Salmo trutta) exposed for 5 days to pH 5 in high calcium water and at 2 temperatures (12°, 4°C) in the laboratory displayed no alterations
in growth or in mucous cell concentration and volume, compared to the control group kept at pH 7.2. Contamination of acid-stressed
young with 230 μg All-1 resulted in significant growth depression and Al accumulation, but in no changes of mucous cell morphometrics. Field tests
in low calcium water produced high mortality at low pH (5.1), but showed consistent effects on mucous cells as in laboratory
experiments. Three-month-old juveniles of brown trout, subjected to decreased pH values at 12° and in high calcium water for
8 days exhibited mucous cell hyperplasia (without hypertrophy) within 3 h of the acid addition. After 120 h sloughing of the
integument occurred with full recovery not possible within a 4-day-recovery period. Although the results presently apply only
to hard water conditions, the differences between juveniles and recently hatched young in tolerance to pH- and Al-mediated
stress may also be of importance for soft waters affected by acid rain. 相似文献
8.
Tetanus Toxin and Botulinum A and C Neurotoxins Inhibit Noradrenaline Release from Cultured Mouse Brain 总被引:4,自引:3,他引:1
The specific binding protein for substance P (SP) was solubilized in an active form from the crude mitochondrial (P2) fraction of bovine brainstem. After incubation with 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS) and 0.1 M NaCl at 0 degrees C for 30 min, the SP binding to the supernatant fraction (100,000 g, 60 min) was determined by the glass fiber filtration method reported by Bruns et al. (1983). The specific [3H]SP binding to the solubilized fraction was highly specific for SP and was displaced by nanomolar concentrations of SP and physalaemin, but only by micromolar concentrations of eledoisin. In addition, the binding was inhibited by GTP (approximately 40% of the specific binding decreased by 10 microM GTP) in both preparations. These results were virtually identical to those of P2 membrane preparations and suggested that this high-affinity SP binding site belongs to the SP-P type. Scatchard analyses of SP binding to the solubilized fraction revealed a single saturable component with a Bmax of 22.0 +/- 5.10 fmol/mg protein and a KD of 0.79 nM, and these values are almost the same as those obtained in the P2 fraction (Bmax = 31.3 +/- 3.56 fmol/mg protein, KD = 0.82 nM). Gel filtration analysis showed that the detergent-SP binding protein complex has two calculated molecular weights of greater than 1,000,000 and 55,000-60,000 (a corresponding Stokes radius of 35.5 nm). 相似文献
9.
Helmut Bäumlein Istvan Nagy† Raimundo Villarroel Dirk Inzé Ulrich Wobus 《The Plant journal : for cell and molecular biology》1992,2(2):233-239
A 2.4 kb fragment containing the 5'-flanking region and the 5'-noncoding sequence of the Vicia faba legumin gene LeB4 mediates high level seed-specific expression in transgenic tobacco plants. Deleted derivatives of this legumin upstream sequence were fused to the npt-II reporter gene to determine the tissue-specific activity of the chimeric constructs in stably transformed tobacco plants. The results indicate the presence of positive regulatory, enhancer-like cis elements within 566 bp of the upstream sequence. Most importantly, however, these elements are only fully functional in conjunction with the core motif CATGCATG of the legumin box around position -95, since destruction of the motif by a 6 bp deletion in an otherwise intact 2.4 kb upstream sequence drastically reduces expression in seeds. At the same time, low level expression in leaves is observed. The occurrence of similar CATGCATG consensus cis elements with alternating purine and pyrimidine base pairs in front of several other plant genes suggests a functional role of the motif in a wider range of plant promoters. 相似文献
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