共查询到20条相似文献,搜索用时 640 毫秒
1.
作物耐低磷适应机制研究进展 总被引:6,自引:0,他引:6
从形态学、生理学、生物化学、分子生物学等方面,综述了作物对低磷胁迫的可能适应机制,重点介绍了碳代谢的改变在作物适应低磷环境上的积极作用,力求为作物耐低磷基因资源筛选及磷高效作物品种改良提供新的思路和理论依据。 相似文献
2.
Clinical transplantation is often complicated by rejection episodes, in which the immune system of the recipient reacts to the foreign transplantation (HLA) antigens on the graft. This immune response includes humoral and cellular components. In the first, B lymphocytes form antibodies to the HLA alloantigens. In the second, CD8+ T lymphocytes recognize and react to HLA class I antigens, and CD4+ T cells react to HLA class II antigens. The frequency and severity of these rejection episodes can be diminished by immunosuppressive drugs, HLA matching between donor and recipient, and immune modulation by blood transfusion. Effective HLA matching between donor and recipient is not always possible and often not necessary. Insight into the factors that influence the T and B cell repertoire after blood transfusion might lead to new approaches to improve graft survival. 相似文献
3.
4.
Immunologic tolerance: collaboration between antigen and lymphokines 总被引:15,自引:0,他引:15
G J Nossal 《Science (New York, N.Y.)》1989,245(4914):147-153
Immunologic tolerance is the process whereby limits are placed on the degree to which lymphocytes respond to an animal's inherent antigens. It is a quantitative rather than an absolute term, as some autoantibody formation is common. Contrary to early hopes, it is not due to some single, simple causative mechanism confined to early developmental stages of the fetal immune system. Rather, self-tolerance results from a variety of complementary mechanisms and feedback loops in the immune system and is thus best seen as part of the general process of immunoregulation. 相似文献
5.
Disease tolerance as a defense strategy 总被引:2,自引:0,他引:2
The immune system protects from infections primarily by detecting and eliminating the invading pathogens; however, the host organism can also protect itself from infectious diseases by reducing the negative impact of infections on host fitness. This ability to tolerate a pathogen's presence is a distinct host defense strategy, which has been largely overlooked in animal and human studies. Introduction of the notion of "disease tolerance" into the conceptual tool kit of immunology will expand our understanding of infectious diseases and host pathogen interactions. Analysis of disease tolerance mechanisms should provide new approaches for the treatment of infections and other diseases. 相似文献
6.
Autoimmunity arises when immune tolerance to specific self-antigens is broken. The mechanisms leading to such a failure remain poorly understood. One hypothesis proposes that infectious agents or antigens can break B or T lymphocyte self-tolerance by expressing epitopes that mimic self. Using a transgenic immunoglobulin model, we show that challenge with self-mimicking foreign antigen rescues B cells from peripheral tolerance independent of T cell help, resulting in the accumulation of self-reactive cells in the lymph nodes and secretion of immunoglobulins that bind to a liver-expressed self-antigen. Therefore, our studies reveal a potentially important mechanism by which B lymphocytes can escape self-tolerance. 相似文献
7.
8.
Nancy P Tagliani E Tay CS Asp P Levy DE Erlebacher A 《Science (New York, N.Y.)》2012,336(6086):1317-1321
The chemokine-mediated recruitment of effector T cells to sites of inflammation is a central feature of the immune response. The extent to which chemokine expression levels are limited by the intrinsic developmental characteristics of a tissue has remained unexplored. We show in mice that effector T cells cannot accumulate within the decidua, the specialized stromal tissue encapsulating the fetus and placenta. Impaired accumulation was in part attributable to the epigenetic silencing of key T cell-attracting inflammatory chemokine genes in decidual stromal cells, as evidenced by promoter accrual of repressive histone marks. These findings give insight into mechanisms of fetomaternal immune tolerance, as well as reveal the epigenetic modification of tissue stromal cells as a modality for limiting effector T cell trafficking. 相似文献
9.
10.
11.
The immune system normally avoids producing antibodies that react with autologous ("self") antigens by censoring self-reactive T and B cells. Unlike the T cell repertoire, antibody diversity is generated within the B cell repertoire in two phases; the first occurs by gene rearrangement in primary lymphoid organs, and the second phase involves antigen-driven hypermutation in peripheral lymphoid organs. The possibility that distinct cellular mechanisms may impose self tolerance at these two different phases of B cell diversification may explain recent findings in transgenic mouse models, in which self-reactive B cells appear to be silenced both by functional inactivation and by physical elimination. 相似文献
12.
Metcalf CJ Graham AL Huijben S Barclay VC Long GH Grenfell BT Read AF Bjørnstad ON 《Science (New York, N.Y.)》2011,333(6045):984-988
Immune clearance and resource limitation (via red blood cell depletion) shape the peaks and troughs of malaria parasitemia, which in turn affect disease severity and transmission. Quantitatively partitioning the relative roles of these effects through time is challenging. Using data from rodent malaria, we estimated the effective propagation number, which reflects the relative importance of contrasting within-host control mechanisms through time and is sensitive to the inoculating parasite dose. Our analysis showed that the capacity of innate responses to restrict initial parasite growth saturates with parasite dose and that experimentally enhanced innate immunity can affect parasite density indirectly via resource depletion. Such a statistical approach offers a tool to improve targeting of drugs or vaccines for human therapy by revealing the dynamics and interactions of within-host regulatory mechanisms. 相似文献
13.
The cyclosporines are a family of cyclic endecapeptides that cause a profound suppression of primary immune stimulation both in vitro and in vivo. Recently, the regulatory protein calmodulin (CaM) has been implicated as a target for cyclosporin A (CsA) binding. This study utilized two less-active isomers of CsA to evaluate the specificity and biological significance of CaM binding. The three cyclosporines exhibited equivalent in vitro binding to CaM, regardless of immunosuppressive activity. Furthermore, CaM-dependent enzyme systems were inhibited equally by active and inactive cyclosporines, but only at concentrations 100 times those necessary to block lymphocyte activation. Thus the exquisite immunosuppressive stereospecificity displayed by cyclosporine isomers is not reflected in the binding to and inhibition of CaM, suggesting that inhibition of CaM-dependent processes is not sufficient to explain the immunosuppressive activity of CsA. 相似文献
14.
Rabbit antiserum to mouse lymphocytes prolonged the survival of mice infected with Plasmodium berghei. Since antilymphocyte serum has a well-defined, potent immunosuppressive effect, the immune response of the host to the parasite actually may contribute to the death of the animal with an acute malarial infection. 相似文献
15.
[目的]研究产复康对免疫功能低下小鼠细胞因子的影响,为进一步研究其对机体免疫功能的影响提供基础:[方法]通过给小鼠2次皮下注射40mg/kg体重的环磷酰胺,建立免疫抑制模型,并分别以10、15、2.0g/kg的剂量灌服产复康,检测小鼠血清中细胞因子IL10、IL-2和TNFα水平的变化,[结果]单一灌服产复康明显提高了正常小鼠血清中的IL-1β、IL-2和TNFα水平;环磷酰胺降低了小鼠血清中IL-1β、IL-2和TNFQ水平;产复康显著提高免疫抑制小鼠血清中IL-1β、IL-2和TNFα水平。[结论]产复康能拮抗环磷酰胺的免疫抑制,提高机体的免疫功能。 相似文献
16.
17.
槲皮素对免疫低下小鼠体液免疫功能的影响 总被引:2,自引:0,他引:2
本试验探讨了不同剂量槲皮素对免疫低下小鼠体液免疫功能的影响。通过氢化可的松或环磷酰胺建立免疫抑制小鼠模型,灌胃不同剂量的槲皮素。10d后测定免疫器官指数、脾脏抗体形成细胞和血清溶血素含量。结果表明,槲皮素高、中剂量组小鼠免疫器官指数、抗体形成细胞OD值及血清溶血素HC50明显高于模型组(P<0.05)。 相似文献
18.
African swine fever(ASF) is an acute and highly contagious disease that causes severe economic losses to the swine industry. ASF is caused by infection of African swine fever virus(ASFV) in domestic pigs, leading to almost 100% mortality. However, no effective vaccines and pharmacologic treatment against ASF are available. ASF poses a severe threat to the swine industry and the economy. Here we summarize potential virus-host cell interaction mechanisms involving the suppression of innate and adaptive immune responses to ASFV entry and infection. These mechanisms include modulation of apoptosis, inhibition of inflammatory responses, reduction of IFN production, inhibition of autophagy, and suppression of MHC-I expression. Insights into immunoevasion strategies by ASFV may shed light on the development of vaccines, as well as preventive and therapeutic drugs. 相似文献
19.
J Walsh 《Science (New York, N.Y.)》1984,223(4643):1374-1375
The National Organ Transplant Act (H.R. 4080) emerged from the House Ways and Means health subcommittee minus the so-called "cyclosporine amendment," a provision which would have extended Medicare coverage to the long-term use of immunosuppressive drugs for organ transplant recipients. Cyclosporine became a focus of dispute because of its high cost. Opponents of the deleted provision argued that it would break the precedent under which Medicare pays for drugs only while a patient is in the hospital. Committee members report that pressure from physicians and patients is building to revive the deleted proposal. 相似文献
20.
分析作物耐盐、耐旱的反应和机制,介绍一些耐盐和耐旱的基因,探讨各种转基因方法的开发和应用,并提出进一步了解响应盐和干旱危害信号级联的生理和分子机制,以增强作物的耐受性。 相似文献