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131.
Characterization of N-linked oligosaccharides by affinoblotting with concanavalin A-peroxidase and treatment of the blots with glycosidases 总被引:13,自引:0,他引:13
Glycoproteins which bind concanavalin A (Con A) can be located on nitrocellulose sheets after electrophoretic transfer from slab gels, by sequential incubation of the sheets with Con A and peroxidase, and visualization of the peroxidase by an insoluble reaction product. We refer to this method as affinoblotting. Differential elution of Con A from the blots by washing the sheets with different concentrations of alpha-methylglycosides is used to demonstrate the affinity of Con A for the oligosaccharide side chains, and to differentiate between proteins with weak and those with high affinity for Con A. Concanavalin A has a high affinity for the four plant glycoproteins (phaseolin, phytohemagglutinin, jackbean alpha-mannosidase, and the glycosylated precursor of Con A) studied here. Incubation of the blots with alpha-mannosidase and endoglycosidase H (endo H) is used to demonstrate that the oligosaccharide chains can be degraded by glycosidases while the proteins are immobilized on the nitrocellulose. With this approach we show here that the four plant glycoproteins used as models in this study interact with Con A through high-mannose oligosaccharide side chains sensitive to alpha-mannosidase and endo H degradation. 相似文献
132.
S Jozan J C Faye J F Tournier J P Tauber J F David F Bayard 《Biochemical and biophysical research communications》1985,133(1):105-112
The responsiveness of the human mammary carcinoma cell line MCF-7 to estradiol and tamoxifen treatment has been studied in different culture conditions. Cells from exponentially growing cultures were compared with cells in their initial cycles after replating from confluent cultures ("confluent-log" cells). It has been observed that estradiol stimulation of tritiated thymidine incorporation decreases with cell density and that "confluent-log" cells are estrogen unresponsive for a period of four cell cycles in serum-free medium conditions. On the other hand, growth of cells replated from exponentially growing, as well as from confluent cultures, can be inhibited by tamoxifen or a combined treatment with tamoxifen and the progestin levonorgestrel. This growth inhibitory effect can be rescued by estradiol when cells are replated from exponentially growing cultures. The growth inhibitory effect cannot be rescued by estradiol alone (10(-10) to 10(-8) M) when cells are replated from confluent cultures. In this condition, the addition of steroid depleted serum is necessary to reverse the state of estradiol unresponsiveness. Serum can be replaced by high density lipoproteins but not by low density lipoproteins or lipoprotein deficient serum. The present data show that estradiol and HDL interact in the control of MCF-7 cell proliferation. 相似文献
133.
Karine Monceau Mariangela Arca Lisa Leprêtre Olivier Bonnard Gérard Arnold Denis Thiéry 《Journal of Insect Behavior》2018,31(1):1-11
Invasive species are now recognized as a major cause of native biodiversity loss worldwide. In the current deleterious context for pollinators, the invasive yellow-legged hornet, Vespa velutina, represents an additional threat to the domestic honeybee, Apis mellifera, in Europe. Therefore, understanding the impact of this predator on honeybee colonies is of major importance. In the present study, we tried to assess the impact of V. velutina on the honeybee foraging and defence behaviour based on the video monitoring of two hives. Balling behaviour is reported here for the first time under natural conditions in A. mellifera against V. velutina in Europe. Although these results are preliminary and should be carefully considered, we found that the number of hornets impacted honeybee foraging and defence behaviours. More defensive behaviours were notified in the hive, which survives slightly longer. This may suggest that selecting for more defensive colonies may provide an interesting perspective. 相似文献
134.
135.
Diverse manifestations of tumorigenicity and immunogenicity displayed by the poorly immunogenic B16-BL6 melanoma transduced with cytokine genes 总被引:4,自引:0,他引:4
Marjorie J. Arca John C. Krauss Scott E. Strome Mark J. Cameron A. E. Chang 《Cancer immunology, immunotherapy : CII》1996,42(4):237-245
We evaluated the in vivo response to the poorly immunogenic B16-BL6 (BL6) murine melanoma genetically altered to secrete
interleukin-2 (IL-2), IL-4, interferon γ (IFNγ) and granulocyte/macrophage-colony-stimulating factor (GM-CSF). Three parameters
were evaluated: (1) tumorigenicity, (2) vaccination of naive animals, and (3) assessment of antitumor reactivity of T cells
derived from tumor-draining lymph nodes (TDLN). Secretion of IL-2 abrogated the tumorigenicity of BL6, while IFNγ and IL-4
partially reduced tumorigenicity, and GM-CSF had no effect. Protective immunity to wild-type tumor challenge could not be
achieved by vaccination with irradiated cytokine-secreting tumors, although IL-2 and IL-4 secretion appeared to retard the
growth of the challenge inoculum significantly. An alternative method to evaluate the immunogenicity of the cytokine-secreting
tumors was to measure the ability of T cells obtained from TDLN to mediate regression of wild-type tumor in adoptive immunotherapy.
Neither IL-2 nor IFNγ secretion resulted in the induction of immune T cells. By contrast, GM-CSF and IL-4 secretion were found
to induce immune T cells in the TDLN with GM-CSF being superior to IL-4. The combined secretion of GM-CSF and IL-4 did not
lead to enhanced induction of immune T cells. GM-CSF secretion was found to up-regulate B7-1 expression in TDLN, consistent
with an increase in the population of antigen-presenting cells. These studies demonstrated that reduced tumorigenicity by
cytokine secretion did not correlate with increased immunogenicity. With the cytokines examined, there was limited capability
of developing protective immunity against the BL6 tumor. Nevertheless, GM-CSF and IL-4 secretion significantly enhanced T
cell immune reactivity to the poorly immunogenic BL6 tumor.
Received: 30 January 1996 / Accepted: 22 March 1996 相似文献
136.
Simon Firek David J. Martin Michael R. Roberts Faye Sturgess Rod Scott John Draper 《The Plant journal : for cell and molecular biology》1996,10(3):569-578
To assess the potential advantages of a transposon-tagging system based on gametophyte-specific transposition a fusion between the anther-specific Arabidopsis thaliana apg promoter and the maize Ac transposase gene was constructed and introduced into tobacco. The ability of this transposase source to activate Ds transposition in a developmentally controlled manner was monitored by crossing to plants harbouring the cell autonomous excision marker gene construct, Ds —SPT. A number of fully green, streptomycin-resistant seedlings resulting from germinal transposition events were observed in the progeny of apg -TPase x Ds —SPT F1 plants. Streptomycin-resistant sectors were not observed in either F1 seedlings or F2 progeny, indicating a complete lack of somatic excision. Further crosses of apg —TPase sources to plants containing Ds—bar herbicide selection excision marker constructs gave reproducible gametophytic excision frequencies of up to 0.3%. Sequencing of Ds excision sites from F2 seedlings derived from single F1 plants revealed various sequence alterations in the original Ds insertion 'footprint' indicative of independent Ds excision events. Independent re-insertion was confirmed by Southern analysis of F2 siblings. It is concluded that apg -controlled Ac transposase expression activates male gametophyte-specific Ds transposition. 相似文献
137.
138.
139.
Whole cells ofTreponema pallidum consumed O2 with lactate in a glucose-depleted medium.d(–) Lactate caused marked stimulation of O2 uptake at a rate similar to that with glucose, whereasl(+) lactate resulted in no increase over the reduced rate observed upon glucose depletion. Lactate oxidation was specific for -hydroxy straight-chain acids of 3,4, and 5 carbons. O2 uptake during lactate oxidation proceeded independently of pyruvate oxidation and required NAD. The product of lactate oxidation was pyruvate.d(–) Lactate-stimulate O2 uptake was sensitive to chlorpromazine and resistant to amytal and cyanide. Glucose did not inhibit the oxidation of lactate as shown by the additive effect of both substrates on O2 uptake. Oxidation of glucose, but not lactate, provided energy necesary for motilibty or maintenance of virulence. A mixture of lactate isomers was formed from glucose with thel(+) isomer concentration remaining constant and thed(–) isomer concentration varying inversely with dissolved O2 concentration. The function of lactate as an oxidizable substrate is apparently quite distinct from that of glucose. 相似文献
140.
Duffy gene frequencies, determined in Senegal, are as follows: Fya=0,0171−Fyb=0,057−Fy=0,9772.
A comparison made with European and African results confirms the prevalence of the Fy gene in Black populations.
Such a study never was realized in Senegal. 相似文献