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排序方式: 共有141条查询结果,搜索用时 252 毫秒
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2.
Patterns of Root Colonization in Epacridaceous Plants Collected from Different Sites 总被引:2,自引:0,他引:2
Root colonization was studied in ten species of the Epacridaceaeat three sites in Victoria by morphological and cross-inoculationexperiments. The sites and genera chosen were Cranbourne [Epacrisimpressa Labill. andLeucopogon ericoides(Smith) R. Br.] andRye [L. parviflorus(Andrews) Lindley] on the Mornington Peninsula,and the Grampians[Astroloma conostephioides(Sond.) Benth.,A.humifusum(Cav.) R. Br.,A pinifolium(R. Br.) Benth,Brachylomadaphnoides(Smith) Benth.,E. impressa, E. impressavar.grandifloraBenth.andStyphelia adscendensR. Br.] in western Victoria. For morphologicalstudies, samples of roots from each species at each site werecleared and stained and examined microscopically. For cross-inoculationstudies, cuttings from each site were struck in potting mediuminoculated with soil from the same and other sites. The ericoidmycorrhizae in the roots of plants found at or grown in Cranbourneand Rye soils were similar. Both were significantly differentfrom the internal hyphae found in the roots of plants foundat or grown in Grampians soils, which were three times largerin diameter and formed dense coils which filled the host celland invaded adjacent epidermal cells. This suggests that morethan one fungus is involved in the relationships, that the MorningtonPeninsula sites had a different fungus from the Grampians siteand that host specificity is low. Vesicular structures werealso found commonly on plants at the Grampians site, in contrastwith other sites. Epacridaceae; root; fungus; mycorrhiza; morphology; inoculation 相似文献
3.
T Kamradt P D Soloway D L Perkins M L Gefter 《Journal of immunology (Baltimore, Md. : 1950)》1991,147(10):3296-3302
In a murine model of T cell-mediated autoimmune disease, experimental autoimmune encephalitis (EAE), 80% of all encephalitogenic T cell clones in H-2u mice use the V beta 8.2 TCR element. To induce EAE in susceptible strains of mice either heat-killed Bordetella pertussis organisms or Bordetella pertussis toxin (PT) must be injected in addition to Ag in CFA. We investigated the mechanisms by which PT facilitates the induction of EAE. Our data show, that PT interferes with the induction of Ag-induced peripheral T cell anergy. Furthermore it has a specific adjuvanticity for the autoantigen pAc1-11 in vivo and acts as a selective mitogen in vitro. We also tested the hypothesis that PT is a bacterial superantigen that specifically expands the V beta 8.2+ subset of T cells, thereby expanding the encephalitogenic T cell clones that are contained in this subset, so that the number of autoreactive T cells is brought over a critical threshold, necessary to induce autoimmune disease. Our data show that PT is not a superantigen. Staphylococcal enterotoxin B, a V beta 8.2-specific superantigen, does not enhance the immune response to the encephalitogenic peptide. 相似文献
4.
Meisel C Bonhagen K Löhning M Coyle AJ Gutierrez-Ramos JC Radbruch A Kamradt T 《Journal of immunology (Baltimore, Md. : 1950)》2001,166(5):3143-3150
The orphan receptor T1/ST2, a member of the IL-1R family, is preferentially expressed on the surface of murine Th2 cells. In this study, we analyzed the kinetics and function of T1/ST2 expression on Th2 cells in vitro. Whereas naive CD4(+) cells did not express T1/ST2, most CD4(+) cells became T1/ST2(+) upon repeated antigenic stimulation under Th2-polarizing conditions. Flow cytometric analyses revealed that the kinetics of T1/ST2 expression on Th2 cells was delayed compared with the kinetics of type 2 cytokine production. Exogenous IL-6, IL-5, IL-1, and TNF-alpha enhanced the expression of T1/ST2 on Th2 cells, and IL-6 was by far most effective in this regard. However, the expression of T1/ST2 did not depend on the presence of IL-6 and was also detected in IL-6-deficient mice. Most important, cross-linking of T1/ST2 provided a costimulatory signal for Th2 but not Th1 cells and directly induced proliferation and type 2 cytokine production. Thus, T1/ST2 is not only a Th2 cell marker but also plays an important role in the activation of Th2 cells. 相似文献
5.
Chen F Kamradt M Mulcahy M Byun Y Xu H McKay MJ Cryns VL 《The Journal of biological chemistry》2002,277(19):16775-16781
Caspases are a conserved family of proteases that play a critical role in the execution of apoptosis by cleaving key cellular proteins at Asp residues and modifying their function. Using an expression cloning strategy we recently developed, we isolated human RAD21/SCC1/MCD1 as a novel caspase substrate. RAD21 is a component of the cohesin complex that holds sister chromatids together during mitosis and repairs double-strand DNA breaks. Interestingly, RAD21 is cleaved by a caspase-like Esp1/separase at the onset of anaphase to trigger sister chromatid separation. Here, we demonstrate that human RAD21 is preferentially cleaved at Asp(279) by caspases-3 and -7 in vitro to generate two major proteolytic products of approximately 65 and 48 kDa. Moreover, we show that RAD21 is specifically proteolyzed by caspases into a similarly sized 65-kDa carboxyl-terminal product in cells undergoing apoptosis in response to diverse stimuli. We also demonstrate that caspase proteolysis of RAD21 precedes apoptotic chromatin condensation and has important functional consequences, viz. the partial removal of RAD21 from chromatin and the production of a proapoptotic carboxyl-terminal cleavage product that amplifies the cell death signal. Taken together, these findings point to an entirely novel function of RAD21 in the execution of apoptosis. 相似文献
6.
Helicobacter pylori infection in wild-type and cytokine-deficient C57BL/6 and BALB/c mouse mutants 总被引:2,自引:0,他引:2
Kamradt AE Greiner M Ghiara P Kaufmann SH 《Microbes and infection / Institut Pasteur》2000,2(6):593-597
Helicobacter pylori causes gastroduodenal ulcer disease in humans. T lymphocytes and their cytokines are thought to play a substantial role in the control of H. pylori infection. To determine the importance of T helper (Th) cytokines and background genes we investigated the natural course of H. pylori infection in BALB/c and C57BL/6 wild-type or mutant mice deficient for either interleukin (IL)-4 or interferon (IFN)-gamma. H. pylori SPM 326 persisted for at least six months in C57BL/6 but was cleared by BALB/c wild-type mice nine weeks postinfection. H. pylori was recovered more frequently from IFN-gamma(-/-) BALB/c and IFN-gamma( -/-) C57BL/6 mice than from the respective wild-type animals. In contrast, IL-4 deficiency had no detectable effect on H. pylori recovery rates from either strain of mice. Our data suggest a protective role of IFN-gamma by mediating inflammation in murine H. pylori infection. In addition, our data emphasize that background genes which differ between BALB/c and C57BL/6 mice regulate the clearance of H. pylori. 相似文献
7.
Andréia S Lessa Bruno D Paredes Juliana V Dias Adriana B Carvalho Luiz Fernando Quintanilha Christina M Takiya Bernardo R Tura Guilherme FM Rezende Antonio C Campos de Carvalho Célia MC Resende Regina CS Goldenberg 《BMC veterinary research》2010,6(1):1-10
Background
Atypical scrapie was first identified in Norwegian sheep in 1998 and has subsequently been identified in many countries. Retrospective studies have identified cases predating the initial identification of this form of scrapie, and epidemiological studies have indicated that it does not conform to the behaviour of an infectious disease, giving rise to the hypothesis that it represents spontaneous disease. However, atypical scrapie isolates have been shown to be infectious experimentally, through intracerebral inoculation in transgenic mice and sheep. The first successful challenge of a sheep with 'field' atypical scrapie from an homologous donor sheep was reported in 2007.Results
This study demonstrates that atypical scrapie has distinct clinical, pathological and biochemical characteristics which are maintained on transmission and sub-passage, and which are distinct from other strains of transmissible spongiform encephalopathies in the same host genotype.Conclusions
Atypical scrapie is consistently transmissible within AHQ homozygous sheep, and the disease phenotype is preserved on sub-passage. 相似文献8.
van Beers JJ Raijmakers R Alexander LE Stammen-Vogelzangs J Lokate AM Heck AJ Schasfoort RB Pruijn GJ 《Arthritis research & therapy》2010,12(6):R219
Introduction
Rheumatoid arthritis (RA) frequently involves the loss of tolerance to citrullinated antigens, which may play a role in pathogenicity. Citrullinated fibrinogen is commonly found in inflamed synovial tissue and is a frequent target of autoantibodies in RA patients. To obtain insight into the B-cell response to citrullinated fibrinogen in RA, its autoepitopes were systematically mapped using a new methodology. 相似文献9.
10.
Kursar M Koch M Mittrücker HW Nouailles G Bonhagen K Kamradt T Kaufmann SH 《Journal of immunology (Baltimore, Md. : 1950)》2007,178(5):2661-2665
Mycobacterium tuberculosis remains one of the top microbial killers of humans causing approximately 2 million deaths annually. More than 90% of the 2 billion individuals infected never develop active disease, indicating that the immune system is able to generate mechanisms that control infection. However, the immune response generally fails to achieve sterile clearance of bacilli. Using adoptive cell transfer into C57BL/6J-Rag1(tm1Mom) mice (Rag1(-/-)), we show that regulatory T cells prevent eradication of tubercle bacilli by suppressing an otherwise efficient CD4+ T cell response. This protective CD4+ T cell response was not correlated with increased numbers of IFN-gamma- or TNF-alpha-expressing cells or general expression levels of IFN-gamma or inducible NO synthase in infected organs compared with wild-type C57BL/6 animals. Furthermore, suppression of protection by cotransferred regulatory T cells was neither accompanied by a general increase of IL-10 expression nor by higher numbers of IL-10-producing CD4+ T cells. 相似文献