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921.
Cell stimulation causes diacylglycerol kinase (DGK) to convert the second messenger diacylglycerol into phosphatidate, thus initiating the resynthesis of phosphatidylinositols and attenuating protein kinase C activity. Of the DGK isoforms so far reported, only porcine DGK from lymphocytes has been characterized in detail. Here we report the isolation and sequencing of complementary DNA clones that together cover the entire region encoding porcine DGK (relative molecular mass 80,000 (80K)). The deduced primary structure of this DGK contains the putative ATP-binding sites, two cysteine-rich zinc finger-like sequences similar to those found in protein kinase C, and two E-F hand motifs, typical of Ca2(+)-binding proteins like calmodulin. Indeed, we find that the activity of this DGK isoform is enhanced by micromolar concentrations of Ca2+ in the presence of deoxycholate or sphingosine. These properties of 80K DGK indicate that its action is probably linked with both of the second messengers diacylglycerol and inositol 1,4,5-trisphosphate. 相似文献
922.
Restoration of normal function in genetically defective myotubes by spontaneous fusion with fibroblasts 总被引:5,自引:0,他引:5
Muscular dysgenesis in mice is a genetic disease of skeletal muscle caused by the recessive mutation mdg. Muscle fibres in affected mice are paralysed because of the failure of excitation-contraction coupling. Unlike normal myotubes in primary culture, dysgenic myotubes do not contract, either spontaneously or in response to electrical stimulation. The deficiency results from mutation of the gene for the skeletal muscle dihydropyridine receptor, an essential sarcolemmal component both of excitation-contraction coupling and of the slow calcium-ion channel. It has recently been shown that the addition of fibroblasts from normal (but not dysgenic) mice to cultures of dysgenic myotubes can restore spontaneous contractions in a small fraction of these myotubes, but the mechanism for this 'rescue' was not determined. In principle, if fibroblast nuclei were able to incorporate into myotubes, such nuclei could then supply the missing muscle-specific gene product. We have now investigated this possibility using nuclear, cytoplasmic and plasmalemmal markers. We report that the rescue to contractile ability in genetically paralysed dysgenic muscle is mediated by the previously unrecognized ability of fibroblasts to fuse spontaneously with developing myotubes. 相似文献
923.
Dose-dependent relaxations were induced by dopamine in human pulmonary arteries that had been contracted with prostaglandin F2 alpha without alpha-adrenergic blocking agents. The dopamine-induced relaxation was inhibited by haloperidol and fluphenazine, but not by domperidone, suggesting that this relaxation was mediated via DA1 receptors. 相似文献
924.
This study examined the individual and simultaneous adsorption of SOx(SO2)and NOx(NO-NO2)on activated carbon prepared from waste palm shell.The adsorption process was examined in a fixed bed reactor at low temperatures(100 300°C).For individual adsorption without any catalytic activation,SOx showed good adsorption whereas NOx was very much poor.In the simultaneous adsorption of SOx and NOx,SOx showed greater adsorption affinity than NOx.For palm shell activated carbon(PSAC)impregnated with metal catalyst(Ni and Ce)the concentration adsorbed profile showed that the amount of SOx adsorbed decreased regularly,while the amount of the adsorbed NOx increased irregularly.The properties of the pure and impregnated PSAC were analyzed by BET,SEM and EDX.These investigations indicated that PSAC impregnated with metal catalyst is the determining factor in the adsorption of SOx and NOx simultaneously. 相似文献
925.
Fashion changes frequently, on monthly, seasonal to yearly basis. In different periods of time, people tried to use different theories to explain the concept of fashion change. Traditional views including trickle down theory, collective selection theory, mass market theory and subculture leadership theory. From the viewpoint of contemporary thoughts, symbolic interactionist theory of fashion and the power of the fashion industry were discussed and used to examine fashion images prevailing in Hong Kong. Hong Kong young consumers were selected as study samples. Focus group interviews and questionnaire survey were used as qualitative and quantitative method. Results shows that to accept fashion change, status (working or studying) had influence in interpreting fashion images. In addition, male and female students had different opinion on selected statements of the symbolic interactionist theory of fashion but no difference was found between working subjects. Marketing implications are discussed with refere 相似文献
926.
Warm feet promote the rapid onset of sleep. 总被引:5,自引:0,他引:5
927.
928.
Benthic macroinvertebrates from four habitat types (river channel, ephemeral side channel, river backwater, and seasonally inundated wetland) were examined from the Green River at the Ouray National Wildlife Refuge, Uintah County, UT, June-August 1991. For major taxa (Nematoda, Oligochaeta, Diptera: Ceratopogonidea, and Chironomidae) were quantified. Chuster analysis of densities showed that habitat types with comparable flow conditions were the most similar. Highest to lowest overall benthic invertebrate densities of the four habitats were as follows: ephemeral side channel, river backwater, seasonally inundated wetland, and river channel. Nematodes were the most abundant taxon in all habitat types and sample dates except the August sample of the river channel and river backwater and the July sample of the seasonally inundated wetland. 相似文献
929.
In Iowa, the northern grasshopper mouse ( Onychomys leucogaster ) previously was known only from the northwestern part of the state. Herein, we report records of O. leucogaster from the 1970s and 1980s that extend its distribution into west-central and southwestern Iowa. These records may represent dispersal movements into these parts of Iowa by southward movements from populations in northwestern Iowa or they may represent eastward movements of individuals from Nebraska prior to channelization of the Missouri River. 相似文献
930.
Following the suppression of renewal of rat taste cells by vinblastine sulphate, the preference for sucrose decreased markedly while the aversion to quinine did not change. The results suggest that the sensitivity of taste cells to sucrose decreases with their aging, but the sensitivity to quinine increases. 相似文献