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1.
Halothane inhibits the neurotoxin stimulated [14C]guanidinium influx through 'silent' sodium channels in rat glioma C6 cells 总被引:1,自引:0,他引:1
We have investigated the effect of pharmacological agents on [14C]guanidinium ion influx through sodium channels in C6 rat glioma and N18 mouse neuroblastoma cells. The sodium channels of the N18 cells can be activated by aconitine alone, indicating that they are voltage-dependent channels. In contrast, sodium channels in the C6 cells require the synergistic action of aconitine and scorpion toxin for activation and are therefore characterized as so-called silent channels. The general anesthetic halothane used at clinical concentrations, specifically inhibited the ion flux through the silent sodium channel of C6 rat glioma cells. The voltage-dependent channels of the N18 cells were insensitive to halothane at the concentrations tested. 相似文献
2.
It has been concluded from circumstantial evidence obtained with HeLa cells in vivo that the phosphorylation of ribosomal protein S6 increases the affinity of 40S particles for mRNP [Duncan, R. and McConkey, E. H. (1982) Eur. J. Biochem. 123, 535-538; Thomas, G., Martin-Pérez, J., Siegmann, M. and Otto, A.M. (1982) Cell 30, 235-242]. This conclusion needs to be tested in vitro in a reinitiating cell-free translation system from growth-competent cells. We have prepared such a system from HeLa cells and have compared the capacity of homologous 40S subunits of various degrees of phosphorylation to enter the existing polysome pool. The 40S subunits' degree of phosphorylation was manipulated by exposing aliquots of growth-stimulated HeLa cells to hyperthermia (see accompanying paper). 40S subunits from heat-shocked and control cells, despite differences in S6 phosphorylation level as verified by two-dimensional electrophoresis, did not differ with respect to their recruitment into the existing polysome fraction. Owing to the reinitiation activity of the translation system, assay times could be kept sufficiently short, to avoid any serious interference by the S6 phosphatase activities of the system. Our results suggest that increased S6 phosphorylation by itself is not sufficient to accelerate the participation of 40S subunits in protein synthesis. 相似文献
3.
Volatile anesthetics inhibit the ion flux through Ca2+-activated K+ channels of rat glioma C6 cells 总被引:2,自引:0,他引:2
Ca2+-activated K+ channels in rat glioma C6 cells were investigated using monolayers of these cells in petri dishes. The ion flux through the channels was studied with 86Rb+ after addition of a Ca2+-ionophore to the incubation medium. Both the influx and efflux of 86Rb+ through these Ca2+-activated K+ channels were inhibited by the general anesthetic halothane (at clinical concentrations). Other volatile anesthetics such as isoflurane, enflurane and methoxyflurane also inhibited the Ca2+-activated K+ channels at clinical concentrations. Inhibition of these channels by general anesthetics could have profound effects on signal transmission in the brain. 相似文献
4.
For several species of lepidoptera, most of the approximately 350-bp
mitochondrial control-region sequences were determined. Six of these
species are in one genus, Jalmenus; are closely related; and are believed
to have undergone recent rapid speciation. Recent speciation was supported
by the observation of low interspecific sequence divergence. Thus, no
useful phylogeny could be constructed for the genus. Despite a surprising
conservation of control-region length, there was little conservation of
primary sequences either among the three lepidopteran genera or between
lepidoptera and Drosophila. Analysis of secondary structure indicated only
one possible feature in common--inferred stem loops with higher-than-random
folding energies-- although the positions of the structures in different
species were unrelated to regions of primary sequence similarity. We
suggest that the conserved, short length of control regions is related to
the observed lack of heteroplasmy in lepidopteran mitochondrial genomes. In
addition, determination of flanking sequences for one Jalmenus species
indicated (i) only weak support for the available model of insect 12S rRNA
structure and (ii) that tRNA translocation is a frequent event in the
evolution of insect mitochondrial genomes.
相似文献
5.
P. S. Oud J. B. J. Henderik A. C. L. M. Huysmans M. M. M. Pahlplatz H. G. Hermkens J. Tas J. James G. P. Vooijs 《Histochemistry and cell biology》1984,80(1):49-57
Summary The protein dyes Light Green and Orange II were studied separately and in combination with the Feulgen-Pararosanilin(SO2) and-Thionin(SO2) method for the simultaneous determination of DNA and protein. — With polyacrylamide modelfilms the pH dependency, specificity and stoichiometry of Light Green and Orange II have been investigated. The results of both staining methods with different biological objects have been compared. — In addition, the Feulgen-Thionin(SO2) method was studied with model films with respect to its specificity and stoichiometry. In biological objects it has been compared with the Feulgen-Pararosanilin(SO2) method. — When combining the Light Green staining with the Feulgen-Pararosanilin(SO2) procedure and the Orange II staining with Feulgen-Thionin-(SO2), both Feulgen-DNA stainings, which were first applied, proved to be unaffected by the following protein staining procedure. When the Feulgen procedure was carried out without the dye, followed by Light Green staining, the latter became reduced when a sulfite water rinse was included but was unaffected when a running tap water rinse was used. In the case of the Orange II staining a serious reduction in dye binding capacity was found in both situations. — When the Feulgen-Pararosanilin(SO2) Light Green procedure was carried out on isolated nuclei with all dyes present, a decrease of protein dye binding was observed, similar to that found with the well-known Feulgen-Pararosanilin(SO2) Naphthol Yellow S combination. It is concluded that in spite of this reduction the latter two combinations can be used for the cytophotometric analysis of DNA and protein in the same object.This work was supported by the Dutch Cancer Foundation Koningin Wilhelmina Fonds grant NUKC 1981-15 相似文献
6.
J. Tas 《The Histochemical journal》1977,9(3):267-276
Synopsis With the introduction of model films of polyacrylamide gel into which purified glycosaminoglycans (GAGs) have been incorporated, the direct recording of metachromatic spectra with virtually no interference of the corresponding orthochromatic peaks has become possible. Because this model system yields situations comparable to those of stained sections under the microscope, it is well suited for investigating qualitative and quantitative aspects of histochemical staining procedures. Previous model experiments have shown that under aqueous conditions only minor differences can be observed between the metachromatic peaks of different GAGs complexed with a suitable dye (e.g. Toluidine Blue O, Thionin, Safranin O, Cresyl Violet, Crystal Violet). In non-aqueous media, such as glycerol and ethylene glycol, the complexes with Toluidine Blue O revealed a special pattern for heparin, having a metachromatic peak (517 nm) about 30 nm lower than that of all other GAGs. This observation has formed the basis of a method for the qualitative microspectro-photometric detection of heparinin situ which was worked out by combining model film experiments with microspectrophotometric data obtained from rat mast cells. Since only a limited number of cells is necessary for obtaining reliable data with this method, the presence of heparin in the cytoplasmic granules of normal human mast cells and basophilic granulocytes could thus be proved directly.Alcian Blue 8GX, another basic dye frequently used in GAG histochemistry, has also been investigated with polyacrylamide films. In contrast to the metachromatic dyes, the rate of staining with Alcian Blue depends to a large extent on the rate of penetration of the dye into the model films. The rate of penetration is also a phenomenon of great importance for dye bindingin situ, where complex basic protein molecules may form a barrier for the Alcian Blue molecules. The model film studies performed so far have yielded conditions that provide maximal staining (up to an optimal level) and a linear relationship between the concentration of GAG and the AB binding. The presence of basic protein, electrostatically bound to the GAG, was not found to influence either the rate of staining or the maximal amount of dye binding.Paper presented at a symposium The Changing directions of carbohydrate histochemistry, at the fifth International Congress of Cytochemistry and Histochemistry in Bucharest, Romania on 1 September 1976. 相似文献
7.
S Tas 《Analytical biochemistry》1990,188(1):33-37
Electrophoretic mobility of DNA through polyacrylamide as well as agarose gels is greatly increased by sodium dodecyl sulfate (SDS). DNA molecules well beyond the conventionally separable size limits are separated readily and rapidly by gel electrophoresis with SDS in a conventional static electric field. Furthermore in optimal concentration gels DNA molecules of similar molecular sizes are separated better from one another in the presence of SDS than without it. Evidence is presented that SDS may act at least in part by altering conformation of DNA. This simple and readily available means for high resolution separation of hitherto impossible sizes of DNA molecules in polyacrylamide and agarose gels in an ordinary static electric field should find general use in molecular genetic analyses. Structural analyses of DNA-protein complexes are also facilitated by virtue of the simultaneous separation of the DNA and protein components on the same gel lane. 相似文献
8.
9.
The study aimed to compare aerobic and aerobic/anoxic stabilization processes in terms of organic matter and the biomass removal efficiencies using a municipal sludge sample. The efficiency of stabilization process was assessed monitoring suspended solids (SS), volatile suspended solids (VSS), total and dissolved organic carbon (TOC, DOC), nitrate, nitrite, and phosphate parameters. The oxygen uptake rate (OUR) measurements were conducted to determine active biomass concentration. On the 30th day of the aerobic stabilization, the SS, VSS and TOC removal efficiencies were 22%, 28% and 55%, respectively. Under aerobic/anoxic conditions, removal efficiencies for SS, VSS and TOC were 25%, 27% and 67%. On the 17th day of the stabilization, SS and VSS removal rates were 60 mg SS/L day and 47 mg VSS/L day for aerobic and 102 mg SS/L day and 63 mg VSS/L day for aerobic/anoxic conditions, respectively. These findings reflected the higher stabilization performance of the aerobic/anoxic conditions. Based on respirometric results, the ratios of the active biomass were decreased to 30% and 24% for the 17th and 30th day of the aerobic stabilization, respectively. Such results have significant implications relative to the activity decrease quantification of the biomass as well as its further application potentials after aerobic or aerobic/anoxic sludge stabilization. 相似文献