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391.
Wang W  Barnaby JY  Tada Y  Li H  Tör M  Caldelari D  Lee DU  Fu XD  Dong X 《Nature》2011,470(7332):110-114
The principal immune mechanism against biotrophic pathogens in plants is the resistance (R)-gene-mediated defence. It was proposed to share components with the broad-spectrum basal defence machinery. However, the underlying molecular mechanism is largely unknown. Here we report the identification of novel genes involved in R-gene-mediated resistance against downy mildew in Arabidopsis and their regulatory control by the circadian regulator, CIRCADIAN CLOCK-ASSOCIATED 1 (CCA1). Numerical clustering based on phenotypes of these gene mutants revealed that programmed cell death (PCD) is the major contributor to resistance. Mutants compromised in the R-gene-mediated PCD were also defective in basal resistance, establishing an interconnection between these two distinct defence mechanisms. Surprisingly, we found that these new defence genes are under circadian control by CCA1, allowing plants to 'anticipate' infection at dawn when the pathogen normally disperses the spores and time immune responses according to the perception of different pathogenic signals upon infection. Temporal control of the defence genes by CCA1 differentiates their involvement in basal and R-gene-mediated defence. Our study has revealed a key functional link between the circadian clock and plant immunity.  相似文献   
392.
Immune homeostasis in tissues is achieved through a delicate balance between pathogenic T-cell responses directed at tissue-specific antigens and the ability of the tissue to inhibit these responses. The mechanisms by which tissues and the immune system communicate to establish and maintain immune homeostasis are currently unknown. Clinical evidence suggests that chronic or repeated exposure to self antigen within tissues leads to an attenuation of pathological autoimmune responses, possibly as a means to mitigate inflammatory damage and preserve function. Many human organ-specific autoimmune diseases are characterized by the initial presentation of the disease being the most severe, with subsequent flares being of lesser severity and duration. In fact, these diseases often spontaneously resolve, despite persistent tissue autoantigen expression. In the practice of antigen-specific immunotherapy, allergens or self antigens are repeatedly injected in the skin, with a diminution of the inflammatory response occurring after each successive exposure. Although these findings indicate that tissues acquire the ability to attenuate autoimmune reactions upon repeated responses to antigens, the mechanism by which this occurs is unknown. Here we show that upon expression of self antigen in a peripheral tissue, thymus-derived regulatory T cells (T(reg) cells) become activated, proliferate and differentiate into more potent suppressors, which mediate resolution of organ-specific autoimmunity in mice. After resolution of the inflammatory response, activated T(reg) cells are maintained in the target tissue and are primed to attenuate subsequent autoimmune reactions when antigen is re-expressed. Thus, T(reg) cells function to confer 'regulatory memory' to the target tissue. These findings provide a framework for understanding how T(reg) cells respond when exposed to self antigen in peripheral tissues and offer mechanistic insight into how tissues regulate autoimmunity.  相似文献   
393.
394.
Wang M  Gamo NJ  Yang Y  Jin LE  Wang XJ  Laubach M  Mazer JA  Lee D  Arnsten AF 《Nature》2011,476(7359):210-213
Many of the cognitive deficits of normal ageing (forgetfulness, distractibility, inflexibility and impaired executive functions) involve prefrontal cortex (PFC) dysfunction. The PFC guides behaviour and thought using working memory, which are essential functions in the information age. Many PFC neurons hold information in working memory through excitatory networks that can maintain persistent neuronal firing in the absence of external stimulation. This fragile process is highly dependent on the neurochemical environment. For example, elevated cyclic-AMP signalling reduces persistent firing by opening HCN and KCNQ potassium channels. It is not known if molecular changes associated with normal ageing alter the physiological properties of PFC neurons during working memory, as there have been no in vivo recordings, to our knowledge, from PFC neurons of aged monkeys. Here we characterize the first recordings of this kind, revealing a marked loss of PFC persistent firing with advancing age that can be rescued by restoring an optimal neurochemical environment. Recordings showed an age-related decline in the firing rate of DELAY neurons, whereas the firing of CUE neurons remained unchanged with age. The memory-related firing of aged DELAY neurons was partially restored to more youthful levels by inhibiting cAMP signalling, or by blocking HCN or KCNQ channels. These findings reveal the cellular basis of age-related cognitive decline in dorsolateral PFC, and demonstrate that physiological integrity can be rescued by addressing the molecular needs of PFC circuits.  相似文献   
395.
K S Lee  R W Tsien 《Nature》1983,302(5911):790-794
Organic inhibitors of calcium influx prevent outward as well as inward current through cardiac calcium channels but do not slow current activation. Although block is antagonized by raising external calcium or barium concentrations, the competitive effect of permeant cations does not occur at the same cation binding site at which inorganic blockers act. Organic drugs show varying degrees of use-dependent block, due in part to blockade of open channels. Nitrendipine blockade of calcium currents requires doses greater than 100-fold higher than expected from radioligand binding to isolated membranes.  相似文献   
396.
As the survey vessels normally take bathymetric measurements in a 'dynamic'environment on the sea surface,the attitude parameters of the vessel are basically required to be introduced measurements related to the sounding datum. A multi-antenna GPSsystem, which can be easy-mounted on a vessel, has proved to be able toprecisely determine its attitude parameters through the combinations ofthe GPS vectors. This study aimed at evaluating such a GPS-basedsystem to determine the attitude parameters for the survey vessels, basedon the data collected both in-land for testing and on-sea for practical use.The precision of the estimates was realized to be around 1.6' for heading,2.3' for pitch, 9.9' for roll, and 0.3 cm for heave, based on the testing data. When system was practically applied to the bathymetric measurements made on-board, the sea depth agreements for the check points can be improved by a significant level of 43%, if a complete set of attitude parameters was in use. As the attitude information was provedto be helpful for the bathymetric measurements, it can be suggested thata multi-antenna GPS system is an economic and effective tool for the deter minations of the attitude parameter, and particularly suitable for the applications of hydrographic surveys.  相似文献   
397.
H Lee  R G Nagele 《Experientia》1988,44(1):60-61
An isolated neural plate or a postnodal piece of early chick embryos, when cultured under appropriate experimental conditions, can undergo morphogenetic movements and form tubular structures closely resembling neural tubes of early chick embryos.  相似文献   
398.
1.Korean Traditional CostumeKorean costume culture was originated from culture of northern horseriding tribe, Scythai culture. In Culture of Korean traditional costume, the basic type of clothing is short jacket and trousers or short jacket, skirt, and wearing hat, Wha (boots) and Lee (deep curved and low heel shoes). It was the cloak as protecting cold and taking Po for outdoor works. We can find stripe neck park of jacket and following round line in down part of sleeve.  相似文献   
399.
卵巢癌是较常见的妇女肿瘤,其生存率较低,因此,控制此病的重点应该是预防。实验室研究显示绿茶具有预防作用,但人群调查则结果不一。茶是我国居民最常用的饮品,如果其预防卵巢癌的作用是确实的,饮茶将是一个较好的预防途径。本研究的目的在于调查常用饮品对卵巢癌的影响,以便为此病的预防提供依据。  相似文献   
400.
This paper discusses the Granger causality test by a spectrum estimator which allows the transfer function to have long memory properties. In traditional methodology the relationship among variables is usually assumed to be short memory or contemporaneous. Hence, we have to make sure they are of the same integrated order, else there might be a spurious regression problem. In practice, not all the variables are fractionally co‐integrated in the economic model. They may have the same random resources, but under a different integrated order. This paper focuses on how to capture the long memory Granger causality effect in the transfer function. This does not necessarily assume the variables are of the same fractional integrated order. Moreover, by the transfer function we construct an estimator to test the long memory effect with the Granger causality sense. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
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