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排序方式: 共有235条查询结果,搜索用时 15 毫秒
1.
The interaction of saponins with phospholipid vesicles was investigated by means of liposomal agglutination or a precipitation assay. Ginsenoside-Rc, which has an α-l-arabinofuranose residue at the non-reducing terminus, exhibited remarkable agglutinability toward egg yolk phosphatidylcholine vesicles, while other saponins lacking this characteristic sugar residue showed less or no agglutinability. The molar ratio of ginsenoside-Rc to egg phosphatidylcholine in the aggregates was estimated to be 0.4–0.5 by a precipitation assay using 14C-labeled egg phosphatidylcholine vesicles. The agglutination was inhibited by p-nitrophenyl α-l-arabinofuranoside but not by p-nitrophenyl β-d-glucopyranoside or arabinogalactan. The results indicated that the α-l-arabinofuranose residue in ginsenoside-Rc should be important for the expression of the agglutinability. The agglutinability of ginsenoside-Rc toward lipid vesicles depended on both the polar head groups and fatty acyl chains of phospholipids. Egg yolk phosphatidylcholine vesicles were strongly agglutinated by ginsenoside-Rc, although sphingomyelin, phosphatidylethanolamine, phosphatidic acid and phosphatidylserine were less agglutinated. The agglutinability of ginsenoside-Rc was effective for phosphatidylcholines with short or unsaturated fatty acyl chains. The results suggested that the interaction of ginsenoside-Rc with phospholipid membranes should be affected not only by the chemical structure of the phospholipid but also by the membrane fluidity. 相似文献
2.
Summary 1-Methylguanine and 7-methylguanine, both metabolic products of tRNA degradation, are known to induce transformation of Chinese hamster fibroblasts in culture. The effects of these compounds on the cell membrane have been studied by the method of Concanavalin A-mediated hemadsorption. 1-Methylguanine or 7-methylguanine induced a 50% increase of Con A-mediated hemadsorption within 20 hours of exposure of the cells to the agent at a concentration of 10-5 M. This alteration was reversed within 13 days when the cells were grown in the control medium. Prolonged treatment with 1-methylguanine or 7-methylguanine resulted in changes which were only slowly reversed during growth of the cells in the control medium. The effect of the methylated purines on the cell membrane could be completely inhibited by simultaneous addition of dibutyryl-cAMP at a concentration of 10-5 M. The possible mechanism of cell membrane alteration by methylated purines and its relevance to transformation in vitro are discussed. 相似文献
3.
R. Kooijman T. J. M. Elzenga P. de Wildt A. Musgrave F. Schuring H. van den Ende 《Planta》1986,169(3):370-378
The mating activity of mating-type plus gametes of Chlamydomonas eugametos depends on light. Cells lost their ability to agglutinate with mating-type minus gametes after a dark period of 30 min. They regained their agglutinability after 10 min exposure to light. Other mating reactions, such as tipping and flagellar tip activation, were not dependent upon light. Since cycloheximide and tunicamycin did not affect the light-induced activation of flagellar agglutinability, no protein synthesis or glycosylation is involved in this process. Equal amounts of biologically active agglutination factor could be extracted from cells placed either in light or in darkness. A minor portion of the active material was found to be located on the flagellar surface of illuminated cells. No active material was found on the flagellar surface of dark-exposed cells, whereas their cell bodies contained the same amount of active material as the cell bodies of illuminated cells. Since a light-induced flow of agglutination factors from the cell body to the flagella could not be detected and dark-exposed cells could be slightly activated by amputation or fixation by glutaraldehyde, we propose that light affects flagellar agglutinability by an in-situ modification of the agglutination factor on the flagella. When mt
+ and mt
- strains were crossed and the progeny examined for light-sensitivity, it was apparent that this phenomenon is not mating type-linked.Abbreviations and symbols FTA
flagellar tip activation
-
mt
+/-
mating type plus or minus
- WGA
wheat-germ agglutinin 相似文献
4.
5.
Ken-ichi Tanaka Shigeru Kohno Takashige Miyazaki Haruko Miyazaki Kotaro Mitsutake Shigefumi Maesaki Mitsuo Kaku Hironobu Koga 《Mycopathologia》1994,127(3):131-134
A latex agglutination test for cryptococcal antigen, the Eiken Latex test (Eiken, Tokyo, Japan), was compared with a monoclonal antibody-based agglutination assay, Pastorex® Cryptococcus (Diagnostics Pasteur, Marneur-la-Coquette, France). In a murine model of disseminated cryptococcosis, the kinetics of the antigen titers by the Eiken Latex were similar to those by the Pastorex® Cryptococcus, but sensitivity was much higher. In HIV-negative patients with pulmonary cryptococcosis, a cryptococcal antigen was detected in 6 of 10 patients by the Eiken Latex test and in only 3 of those patients by the Pastorex® Cryptococcus. The results indicate that the Eiken Latex is more sensitive for the detection of the cryptococcal antigen, even in non-disseminated cryptococcosis. The sensitivity and specificity of the Eiken Latex were examined using 195 sera from 25 patients with pulmonary cryptococcosis and 170 patients with non-cryptococcosis. The cutoff value of 1:8 showed a sensitivity of 76% (19/25) and a specificity of 98.9% (168/170). 相似文献
6.
Dog-DAT: a direct agglutination test using stabilized, freeze-dried antigen for the serodiagnosis of canine visceral leishmaniasis 总被引:2,自引:0,他引:2
Linda Oskam Rob J. Slappendel Eef G.M. Beijer Nel C.M. Kroon Cor W. van Ingen Seray Özensoy Yusuf Özbel Wiepko J. Terpstra 《FEMS immunology and medical microbiology》1996,16(3-4):235-239
Abstract We have evaluated the use of an improved direct agglutination test (DAT) based on stable, freeze-dried antigen for the detection of anti- Leishmania antibodies in canine serum samples. With a cut-off value of 1:640, the sensitivity of the DAT was shown to be 100% and the specificity of the test was 98.8%. 相似文献
7.
8.
Enrique J. del Pino Marcelo O. Cabada María C. Fonio 《Molecular reproduction and development》1981,4(2):97-104
Various plant lecins were employed in cell agglutination experiments to ascertain the presence of specific saccharides in the surface of B arenarum and L chaquensis spermatozoa. B arenarum spermatozoa were specifically agglutinated with Concanavalin A (Con A), phytohemagglutinin P (PHA-P), and wheat germ agglutinin (WGA), but not with soybean agglutinin (SBA). In contrast, L chaquensis spermatozoa were strongly agglutinated by SBA, WGA, and PHA-P. L chaquensis spermatozoa did not agglutinate with Con A even at high concentrations. Lectinmediated sperm agglutination was inhibited in the presence of specific lectinbinding sugars. Spermatozoa from both species were agglutinated randomly with all lectins suggesting a uniform distribution in the sperm surface of the lectinbinding saccharide ligands. B arenarum sperm agglutination induced by Con A is sensitive to temperature. B arenarum spermatozoa are more agglutinable at 24°C than at 4°C. These results suggest that lectin-binding site mobility is necessary for sperm agglutination. 相似文献
9.
Starch biosynthesis and degradation was studied in seedlings and mature plants of Euphorbia heterophylla L. and E. myrsinites L. Mature embryos, which lack starch grains in the non-articulated laticifers, develop into seedlings that accumulate starch rapidly when grown either in the light or the dark. Starch accumulation in laticifers of dark-grown seedlings was ca. 47 and 43% of total starch in light-grown controls in E. heterophylla and E. myrsinites, respectively. In light-grown seedlings, starch was present in laticifers as well as parenchyma of stems and leaves, whereas in dark-grown seedlings starch synthesis was almost exclusively limited to laticifers. In 7-month-old plants placed into total darkness, the starch in chyma was depleted within 6 d, whereas starch in laticifers was not mobilized. The starch content of latex in plants during development of floral primordia, flowering, and subsequent fruit formation remained rather constant. The results indicate that laticifers in seedlings divert embryonal storage reserves to synthesize starch even under stress conditions (darkness) in contrast to other cells, and that starch accumulated in laticifers does not serve as a metabolic reserve. The laticifer in Euphorbia functions in the accumulation and storage of secondary metabolites yet retains the capacity to produce, but not utilize starch, a primary metabolite. 相似文献
10.
A. R. STEVENS T. KILPATRICK E. WILLAERT A. CAPRONI 《The Journal of eukaryotic microbiology》1977,24(2):316-324
SYNOPSIS. Antisera were raised against plasma membrane-enriched fractions of the species Acanthamoeba castellanii and Acanthamoeba culbertsoni to determine whether cell-surface antigens would facilitate species identification of Acanthamoeba isolated from the environment or in human infections. Acanthamoeba castellanii and A. culbertsoni plasma membranes were purified, after homogenization, by differential and isopycnic centrifugation. Electron microscopic examination of purified membrane samples showed an enrichment of membranes with a typical trilaminar structure. Occasionally, mitochondria were recognized in the electron microscope preparations. 5′-Nucleotidase, Mg2+-ATPase, and alkaline phosphatase were enriched 11-fold, 2-fold, and 7-fold, respectively, in the A. castellanii membranes, as determined from analyses of the enzyme activities in whole cell homogenates and membrane preparations. 5′-Nucleotidase was not detected in A. culbertsoni, but the activities of Mg2+-ATPase and alkaline phosphatase were increased 2- to 3-fold. Both membrane preparations showed no glucose-6-phosphatase activity and less than 5% contamination with succinic dehydrogenase. From assays of acid phosphatase activity, the most apparent contamination of the plasma membrane preparations was with membranes of phagocytic vacuoles. Acanthamoeba castellanii membrane antisera produced significant agglutination and fluorescence of homologous cells to titers of 1:8192 and 1:1024, respectively. Acanthamoeba polyphaga and Acanthamoeba rhysodes gave the most cross-reactions in heterologous tests. They were agglutinated to a titer of 1:128 and positively fluoresced to titers of 1:32 and 1:64, respectively. Antisera of A. culbertsoni membrane agglutinated homologous cells at a dilution up to 1:4096 and produced homologous fluorescent titers up to 1:512. Other than agglutination of A. polyphaga to a titer of 1:128, these antisera did not cross-react significantly with any remaining heterologous species. Three new isolates were identified with these plasma membrane antisera: 2 of them, contaminants from tumor tissue cultures, were identified as A. culbertsoni. Preliminary information is also given on the use of the membrane antisera for species identification of Acanthamoeba in several new cases of amebic encephalitis. 相似文献