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排序方式: 共有1939条查询结果,搜索用时 120 毫秒
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Anna Maria Fausto Gabriella Gambellini Massimo Mazzini Antonella Cecchettini Maria Teresa Locci Massimo Masetti Franco Giorgi 《Development, growth & differentiation》2001,43(6):725-733
In mid-embryogenesis, the stick insect Carausius morosus comes to be comprised of three distinct districts: the embryo proper, the yolk sac and the perivitelline fluid. A monolayered epithelium, the so-called serosa membrane, encloses the yolk sac and its content of vitellophages and large yolk granules. During embryonic development, the yolk sac declines gradually in protein concentration due to Vt polypeptides undergoing limited proteolysis to yield a number of Vt cleavage products of lower molecular weights. mAbs 1D1 and 5H11 are monoclonal antibodies raised against some of the Vt cleavage products generated by this process in the yolk sac. At the confocal microscope, antibody fluorescence is initially associated with a few yolk granules, while it is gradually displaced in the cytosolic spaces of the vitellophages. With the proceeding of embryonic development, label appears also in the serosa membrane in the form of clustered dots. At the ultrastructural level, gold particles are initially associated with the vitellophages that are labeled on a few yolk granules and in the cytosolic space flanking the yolk granules. Subsequently, the serosa cells become labeled on vesicles close to the yolk granules or just underneath the plasma membrane. Inside the serosa cells, label is also associated with granules budding from the Golgi apparatus, but never with the intercellular channels percolating the serosa membrane. These observations are interpreted as indicating that Vt cleavage products leak out from the yolk granules into the cytosolic spaces of the vitellophages and are eventually transferred to the perivitelline fluid via transcytosis through the serosa cells. 相似文献
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Abstract The role of calcium during the synthesis, secretion and molecular organization of the primary cell-wall polysaccharides is the topic of this review. With the exception of callose synthase, the in vitro activity of all polysaccharide synthases is not controlled by Ca2+ ions. However, changes in the intracellular Ca2+ level could control the rate of exocytotic fusion of the secretory vesicles containing cell-wall matrix polysaccharides. In particular, the ability of Ca2+ to regulate the fusion of secretory vesicles with the plasma membrane is due to a class of Ca2+-dependent phospholipid-binding proteins known as annexins. The ionic interactions between calcium and the negatively charged homogalacturonan domains of the pectins are important not only for the mechanical properties of the wall but also for the gel-properties of these complex biopolymers. 相似文献
5.
Peter Leport Cartesio Favalli M.Gabriella Santoro Cristine Rinaldi Bernard M. Jaffe 《Life sciences》1982,30(14):1219-1223
Two hundred seventy-one B-16 melanoma-bearing mice were randomized and treated for 4 days with either control diluent, 10 μg of 16, 16-dimethyl-PGE2-methyl-ester (di-M-PGE2), chemotherapy, or chemotherapy plus di-M-PGE2. The chemotherapeutic regimens included adriamycin (7.5 mg/kg), 5-fluorouracil (250 mg/kg), nitrogen mustard (5 mg/kg), and vincristine (0.5 mg/kg). The number of plaque-forming cells and hemagglutinin titers in response to sheep erythrocytes were used as measures of humoral immunity while cellular immunity was assessed by evaluation of delayed hypersensitivity. As we previously reported, the presence of subcutaneous B-16 tumors induced substantial immunosuppression and this suppression was reversed by treatment with di-M-PGE2. Treatment with all four chemotherapeutic agents induced profound immunosuppression. Similarly, the addition of di-M-PGE2 to the chemotherapy protocols resulted in significant augmentation of cellular and humoral immunity. 相似文献
6.
S Ronchi M Galliano L Minchiotti B Curti N G Rudie D J Porter H J Bright 《The Journal of biological chemistry》1980,255(13):6044-6046
The flavoenzyme D-amino acid oxidase (Eo) is rapidly chlorinated by N-chloro-D-leucine (Rudie, N.G., Porter, D.J.T., and Bright, H.J. (1980) J. Biol. Chem. 255, 498-508). We have carried out chymotryptic digestion of E0-36Cl2 and find that all of the radiolabel is located in a heptapeptide having [3.5-36Cl2]chlorotyrosine as the COOH-terminal residue. This heptapeptide, having the sequence -Asp-Leu-Glu-Arg-Gly-Ile-Tyr-, is located within a larger fragment obtained previously from cyanogen bromide cleavage of E0. These results demonstrate that the target for chlorination in E0 must be a single tyrosine residue and provide, when taken together with previous findings, the first clear evidence for the identity and location of an active site residue in the polypeptide chain of D-amino oxidase. 相似文献
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Tallman Gary; Zhu Jianxin; Mawson Bruce T.; Amodeo Gabriella; Nouhi Zepedeh; Levy Kathleen; Zeiger Eduardo 《Plant & cell physiology》1997,38(3):236-242
Facultative CAM plants such as Mesembryanthemum crystallinum(ice plant) possess C3 metabolism when unstressed but developCAM under water or salt stress. When ice plants shift from C3metabolism to CAM, their stomata remain closed during the dayand open at night. Recent studies have shown that the stomatalresponse of ice plants in the C3 mode depends solely on theguard cell response to blue light. Recent evidence for a possiblerole of the xanthophyll, zeaxanthin in blue light photoreceptionof guard cells led to the question of whether changes in theregulation of the xanthophyll cycle in guard cells parallelthe shift from diurnal to nocturnal stomatal opening associatedwith CAM induction. In the present study, light-dependent stomatalopening and the operation of the xanthophyll cycle were characterizedin guard cells isolated from ice plants shifting from C3 metabolismto CAM. Stomata in epidermis detached from leaves with C3 metabolismopened in response to white light and blue light, but they didnot open in response to red light. Guard cells from these leavesshowed light-dependent conversion of violaxan-thin to zeaxanthin.Induction of CAM by NaCI abolished both white light- and bluelight-stimulated stomatal opening and light-dependent zeaxanthinformation. When guard cells isolated from leaves with CAM weretreated with 100 mM ascorbate, pH 5.0 for 1 h in darkness, guardcell zeaxanthin content increased at rates equal to or higherthan those stimulated by light in guard cells from leaves inthe C3 mode. The ascorbate effect indicates that chloroplastsin guard cells from leaves with CAM retain their competenceto operate the xanthophyll cycle, but that zeaxanthin formationdoes not take place in the light. The data suggest that inhibitionof light-dependent zeaxanthin formation in guard cells mightbe one of the regulatory steps mediating the shift from diurnalto nocturnal stomatal opening typical of plants with CAM. (Received July 5, 1996; Accepted December 12, 1996) 相似文献
9.
Ziv M. Machnes Tony C. T. Huang Philip K. Y. Chang Raminder Gill Nicholas Reist Gabriella Dezsi Ezgi Ozturk Francois Charron Terence J. O’Brien Nigel C. Jones R. Anne McKinney Moshe Szyf 《PloS one》2013,8(10)
Epilepsy is a chronic brain disorder involving recurring seizures often precipitated by an earlier neuronal insult. The mechanisms that link the transient neuronal insult to the lasting state of epilepsy are unknown. Here we tested the possible role of DNA methylation in mediating long-term induction of epileptiform activity by transient kainic acid exposure using in vitro and in vivo rodent models. We analyzed changes in the gria2 gene, which encodes for the GluA2 subunit of the ionotropic glutamate, alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid receptor and is well documented to play a role in epilepsy. We show that kainic acid exposure for two hours to mouse hippocampal slices triggers methylation of a 5’ regulatory region of the gria2 gene. Increase in methylation persists one week after removal of the drug, with concurrent suppression of gria2 mRNA expression levels. The degree of kainic acid-induced hypermethylation of gria2 5’ region varies between individual slices and correlates with the changes in excitability induced by kainic acid. In a rat in vivo model of post kainic acid-induced epilepsy, we show similar hypermethylation of the 5’ region of gria2. Inter-individual variations in gria2 methylation, correlate with the frequency and intensity of seizures among epileptic rats. Luciferase reporter assays support a regulatory role for methylation of gria2 5’ region. Inhibition of DNA methylation by RG108 blocked kainic acid-induced hypermethylation of gria2 5’ region in hippocampal slice cultures and bursting activity. Our results suggest that DNA methylation of such genes as gria2 mediates persistent epileptiform activity and inter-individual differences in the epileptic response to neuronal insult and that pharmacological agents that block DNA methylation inhibit epileptiform activity raising the prospect of DNA methylation inhibitors in epilepsy therapeutics. 相似文献
10.
Dávid Kurszán Jász Ágnes Lilla Szilágyi Eszter Tuboly Bálint Baráth Anett Roxána Márton Petra Varga Gabriella Varga Dániel Érces Árpád Mohácsi Anna Szabó Renáta Bozó Kamilla Gömöri Anikó Görbe Mihály Boros Petra Hartmann 《Journal of cellular and molecular medicine》2021,25(11):5113-5123
Albeit previous experiments suggest potential anti-inflammatory effect of exogenous methane (CH4) in various organs, the mechanism of its bioactivity is not entirely understood. We aimed to investigate the potential mitochondrial effects and the underlying mechanisms of CH4 in rat cardiomyocytes and mitochondria under simulated ischaemia/reperfusion (sI/R) conditions. Three-day-old cultured cardiomyocytes were treated with 2.2% CH4-artificial air mixture during 2-hour-long reoxygenation following 4-hour-long anoxia (sI/R and sI/R + CH4, n = 6-6), with normoxic groups serving as controls (SH and SH + CH4; n = 6-6). Mitochondrial functions were investigated with high-resolution respirometry, and mitochondrial membrane injury was detected by cytochrome c release and apoptotic characteristics by using TUNEL staining. CH4 admixture had no effect on complex II (CII)-linked respiration under normoxia but significantly decreased the complex I (CI)-linked oxygen consumption. Nevertheless, addition of CH4 in the sI/R + CH4 group significantly reduced the respiratory activity of CII in contrast to CI and the CH4 treatment diminished mitochondrial H2O2 production. Substrate-induced changes to membrane potential were partially preserved by CH4, and additionally, cytochrome c release and apoptosis of cardiomyocytes were reduced in the CH4-treated group. In conclusion, the addition of CH4 decreases mitochondrial ROS generation via blockade of electron transport at CI and reduces anoxia-reoxygenation-induced mitochondrial dysfunction and cardiomyocyte injury in vitro. 相似文献