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41.
Wim E. J. M. Ghijsen Elly Besselsen Vincent Geukers Willem Kamphuis Fernando H. Lopes da Silva 《Journal of neurochemistry》1992,59(2):482-486
The effect of long-term potentiation (LTP) on endogenous amino acid release from rat hippocampus slices was studied. LTP was induced in vivo by application of a tetanus (200 Hz, 200 ms) to the Schaffer collateral fibers in unanesthetized rats. Endogenous release of glutamate and gamma-aminobutyric acid (GABA) was investigated 60 min after tetanization in CA1 subslices of potentiated and control rats. No significant effects of LTP were observed in basal and K(+)-induced Ca(2+)-independent release components of these amino acids. In contrast, K(+)-induced Ca(2+)-dependent release of both glutamate and GABA increased approximately 100% in slices from potentiated rats. No differences were observed in total content of glutamate and GABA between the subslices from control and LTP animals. These results suggest a persistent increase in the recruitment of the presynaptic vesicular pool of glutamate and GABA during LTP. 相似文献
42.
43.
Henrika G. M. Tiedink Laura H. J. De Haan Wim M. F. Jongen Jan H. Koeman 《Cell biology and toxicology》1991,7(4):371-386
4-chloro-methoxyindole is a naturally occurring compound in Vicia faba which can easily react with nitrite to form a N-nitroso compound. In this in vitro study, the potential genotoxic effects of nitrosated 4-chloro-6-methoxyindole and its structural analogue 4-chloroindole were evaluated for the first time by using both Salmonella and Chinese hamster V79 cells. Additionally, the inhibition of gap junctional intercellular communication in V79 cells by these compounds was determined; this is a validated parameter for tumor-promoting activity. Most assays were also performed with nitrosated indole-3-acetonitrile, a naturally occurring compound in brassicas. Both nitrosated chloroindoles were highly mutagenic to Salmonella typhimurium TA100 without the need of exogenous metabolic activation and were potent inducers of Sister Chromatid Exchanges. Nitrosated indole-3-acetonitrile generated the same effects, although at much higher concentrations. Equivocal results were obtained for the nitrosated chloroindoles in a forward mutation assay using the hypoxanthine guaninephosphoribosyltransferase locus. All nitrosated indole compounds significantly inhibited gap junctional intercellular communication. These results indicate that nitrosated chloroindoles and nitrosated indole-3-acetonitrile should be considered as mutagens and agents with potential tumor-promoting capacity.Abbreviations BrdU
5-bromo-2-deoxyuridine
- 4Cl
4-chloroindole
- 4C6MI
4-chloro-6-methoxy-indole
- DMSO
dimethyl sulfoxide
- EBSS
Earle's balanced salt solution
- EMS
ethyl methanesulfonate
- GJIC
gap junctional intercellular communication
- HBSS
Hanks balanced salt solution
- HGPRT
hypoxanthine guaninephosphoribosyl transferase
- I3A
indole-3-acetonitrile
- MNNG
1-methyl-1-nitroso-3-nitroguanidine
- NOC
N-nitroso compounds
- NQO
4-nitroquinolone-N-oxide
- SCE
sister chromatid exchange
- 6TG
6-thioguanine
- TPA
12-O-tetradecanoylphorbol-13-acetate 相似文献
44.
Behavioural responses of two small ermine moth species (Lepidoptera: Yponomeutidae) to plant constituents 总被引:1,自引:0,他引:1
Wim Van Drongelen 《Entomologia Experimentalis et Applicata》1980,28(1):54-58
On the basis of electrophysiological screening of lateral and medial styloconic sensilla of caterpillars of Yponomeuta species, several hypotheses concerning behavioural effects of plant constituents can be posed (Van Drongelen, 1979). Feeding experiments have been carried out with intact larvae of Y. cagnagellus (Hb.) and Y. evonymellus (L.). Both species display neural responses to dulcitol, phloridzin and prunasin. Leaf discs of the host plants of these species were modified using these three constituents and effects were studied in choice and non-choice situations. Dulcitol appears to stimulate food intake of both species, whereas phloridzin acts as a deterrent exclusively in a choice situation. Prunasin inhibits feeding of Y. cagnagellus in a choice situation, but Y. evonymellus does not show a reaction to this compound at the concentration applied. Neural mechanisms probably underlying these behaviours are discussed.
Supported by the Foundation for Fundamental Biological Research (BION), subsidized by the Netherlands Organization for the Advancement of Pure Research (ZWO). 相似文献
Zusammenfassung Aufgrund elektrophysiologischer Versuche mit lateralen und medialen Sensilla styloconica von Yponomeuta-Arten können mehrere Hypothesen über Verhaltenseffekte von Pflanzenbestandteilen aufgestellt werden (Van Drongelen, 1979). Y. cagnagellus und Y. evonymellus zeigen neurale Reaktionen auf Dulcitol, Phlorizin und Prunasin.Es wurden Frassexperimente mit intakten Raupen beider Arten durchgeführt. Blattscheiben der Wirtspflanzen wurden mit den genannten Stoffen modifiziert, und die Effekte wurden in Wahl- und Nichtwahlversuchen studiert. Dulcitol scheint die Futteraufnahme beider Arten anzuregen, während Phlorizin als Abhaltestoff wirkt und zwar nur in einer Wahlsituation. Prunasin verhindert Fressen bei Y. cagnanellus in einer Wahlsituation, während Y. evonymellus auf diesen Stoff in der geprüften Konzentration nicht reagiert. Neurale Mechanismen, welche wahrscheinlich diesem Verhalten zugrunde liegen, werden diskutiert.
Supported by the Foundation for Fundamental Biological Research (BION), subsidized by the Netherlands Organization for the Advancement of Pure Research (ZWO). 相似文献
45.
Liposomes were prepared from phosphatidylcholine and cardiolipin in a KCl medium and suspended in a choline chloride medium with safranine. When efflux of K+ was induced by valinomycin, spectral shifts characteristic of stacking were observed. Ca2+ inhibited the rate of stacking in a competitive manner with a Ki of about 200 muM, while La3+ was about 10 times more potent. When liposomes were prepared from phospholipids with a higher ratio of cardiolipin to phosphatidylcholine the inhibition was more potent. No effect on the stacking phenomena was seen when CA2+ was added after the stacking was completed. When CA2+ or an organic cation with four charges, spermine was trapped in the intraliposomal compartment, no significant change in the rate of stacking was seen. However, the extent of stacking was decreased. It is suggested that safranine is driven by a diffusion potential to a site that is inaccessible to CA2+ in the medium, presumably to the inner boundaries of the liposomal membranes. 相似文献
46.
Liposomes were prepared from phosphatidylcholine and cardiolipin in a KCl medium and suspended in a choline chloride medium with safranine. When efflux of K+ was induced by valinomycin, spectral shifts characteristic of stacking were observed. Ca2+ inhibited the rate of stacking in a competitive manner with a Ki of about 200 μM, while La3+ was about 10 times more potent. When liposomes were prepared from phospholipids with a higher ratio of cardiolipin to phosphatidyl-choline the inhibition was more potent. No effect on the stacking phenomena was seen when Ca2+ was added after the stacking was completed. When Ca2+ or an organic cation with four charges, spermine, was trapped in the intraliposomal compartment, no significant change in the rate of stacking was seen. However, the extent of stacking was decreased. It is suggested that safranine is driven by a diffusion potential to a site that is inaccessible to Ca2+ in the medium, presumably to the inner boundaries of the liposomal membranes. 相似文献
47.
Summary Soluble enzymes were immobilized and visualized by polyacrylamide gel slabs, impregnated with the incubation medium including auxiliairy enzymes. The method has several advantages over existing techniques which make use of gel films or a semipermeable membrane. The diffusion of tissue compounds is effectively limited, while auxiliary enzymes may be operative. Moreover the viscosity of the medium is temperature-independent so that the incubation temperature can be varied.To demonstrate the suitability of the method glycerol-3-phosphate dehydrogenase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, hexokinase, phosphoglucomutase and aldolase were visualized in human or rat skeletal muscle. Cytosolic and mitochondrial glycerol-3-phosphate dehydrogenase were both visualized in the absence of added NAD+ and menadione.For the visualization of ATP producing enzymes, like creatine kinase and pyruvate kinase, the method is not suitable. 相似文献
48.
49.
Developmental mechanisms not only produce an organismal phenotype, but they also structure the way genetic variation maps to phenotypic variation. Here, we revisit a computational model for the evolution of ontogeny based on cellular automata, in which evolution regularly discovered two alternative mechanisms for achieving a selected phenotype, one showing high modularity, the other showing morphological integration. We measure a primary variational property of the systems, their distribution of fitness effects of mutation. We find that the modular ontogeny shows the evolution of mutational robustness and ontogenic simplification, while the integrated ontogeny does not. We discuss the wider use of this methodology on other computational models of development as well as real organisms. 相似文献
50.
Ingrid M. Lubbers Matty P. Berg Gerlinde B. De Deyn Wim H. van der Putten Jan Willem van Groenigen 《Global Change Biology》2020,26(3):1886-1898
Soil faunal activity can be a major control of greenhouse gas (GHG) emissions from soil. Effects of single faunal species, genera or families have been investigated, but it is unknown how soil fauna diversity may influence emissions of both carbon dioxide (CO2, end product of decomposition of organic matter) and nitrous oxide (N2O, an intermediate product of N transformation processes, in particular denitrification). Here, we studied how CO2 and N2O emissions are affected by species and species mixtures of up to eight species of detritivorous/fungivorous soil fauna from four different taxonomic groups (earthworms, potworms, mites, springtails) using a microcosm set‐up. We found that higher species richness and increased functional dissimilarity of species mixtures led to increased faunal‐induced CO2 emission (up to 10%), but decreased N2O emission (up to 62%). Large ecosystem engineers such as earthworms were key drivers of both CO2 and N2O emissions. Interestingly, increased biodiversity of other soil fauna in the presence of earthworms decreased faunal‐induced N2O emission despite enhanced C cycling. We conclude that higher soil fauna functional diversity enhanced the intensity of belowground processes, leading to more complete litter decomposition and increased CO2 emission, but concurrently also resulting in more complete denitrification and reduced N2O emission. Our results suggest that increased soil fauna species diversity has the potential to mitigate emissions of N2O from soil ecosystems. Given the loss of soil biodiversity in managed soils, our findings call for adoption of management practices that enhance soil biodiversity and stimulate a functionally diverse faunal community to reduce N2O emissions from managed soils. 相似文献