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991.
Fungal resistance to plant antibiotics as a mechanism of pathogenesis. 总被引:12,自引:0,他引:12
Many plants produce low-molecular-weight compounds which inhibit the growth of phytopathogenic fungi in vitro. These compounds may be preformed inhibitors that are present constitutively in healthy plants (also known as phytoanticipins), or they may be synthesized in response to pathogen attack (phytoalexins). Successful pathogens must be able to circumvent or overcome these antifungal defenses, and this review focuses on the significance of fungal resistance to plant antibiotics as a mechanism of pathogenesis. There is increasing evidence that resistance of fungal pathogens to plant antibiotics can be important for pathogenicity, at least for some fungus-plant interactions. This evidence has emerged largely from studies of fungal degradative enzymes and also from experiments in which plants with altered levels of antifungal secondary metabolites were generated. Whereas the emphasis to date has been on degradative mechanisms of resistance of phytopathogenic fungi to antifungal secondary metabolites, in the future we are likely to see a rapid expansion in our knowledge of alternative mechanisms of resistance. These may include membrane efflux systems of the kind associated with multidrug resistance and innate resistance due to insensitivity of the target site. The manipulation of plant biosynthetic pathways to give altered antibiotic profiles will also be valuable in telling us more about the significance of antifungal secondary metabolites for plant defense and clearly has great potential for enhancing disease resistance for commercial purposes. 相似文献
992.
For pollination studies of forest species it is sometimes only possible to work on those flowers nearest to the ground. We test whether using low flowers introduces bias, by measuring height effects on bird visitation and fruit set in one mistletoe species pollinated by bellbirds in New Zealand. At this site, previous studies have shown fruit set near the ground to be pollen limited. We measured fruit set on 32 mistletoes at different heights in 11 host trees. Mistletoe fruit set varied significantly among host trees but did not vary with height. Although bellbirds generally forage preferentially in the upper part of the forest, mistletoe flowers appear to be attractive enough to ensure adequate visitation and fruit set at all heights. 相似文献
993.
Joong Kyu Kim Mark Klinger Jonathan Benjamin Yuanyuan Xiao David J. Erle Dan R. Littman Nigel Killeen 《PloS one》2009,4(8)
Signaling through the T cell antigen receptor (TCR) is important for the homeostasis of naïve and memory CD4+ T cells. The significance of TCR signaling in regulatory T (Treg) cells has not been systematically addressed. Using an Ox40-cre allele that is prominently expressed in Treg cells, and a conditional null allele of the gene encoding p56Lck, we have examined the importance of TCR signaling in Treg cells. Inactivation of p56Lck resulted in abnormal Treg homeostasis characterized by impaired turnover, preferential redistribution to the lymph nodes, loss of suppressive function, and striking changes in gene expression. Abnormal Treg cell homeostasis and function did not reflect the involvement of p56Lck in CD4 function because these effects were not observed when CD4 expression was inactivated by Ox40-cre.The results make clear multiple aspects of Treg cell homeostasis and phenotype that are dependent on a sustained capacity to signal through the TCR. 相似文献
994.
Alexander G. Volkov Astian J. Waite Joseph D. Wooten Vladislav S. Markin 《Plant signaling & behavior》2012,7(2):282-284
The circadian clock regulates a wide range of electrophysiological and developmental processes in plants. Here, we discuss the direct influence of a circadian clock on biologically closed electrochemical circuits in vivo. The biologically closed electrochemical circuits in the leaves of C. miniata (Kaffir lily), Aloe vera and Mimosa pudica, which regulate their physiology, were analyzed using the charge stimulation method. Plants are able to memorize daytime and nighttime. Even at continuous light or darkness, plants recognize nighttime or daytime and change the input resistance. The circadian clock can be maintained endogenously and has electrochemical oscillators, which can activate ion channels in biologically closed electrochemical circuits. The activation of voltage gated channels depends on the applied voltage, electrical charge, and the speed of transmission of electrical energy from the electrostimulator to plants. 相似文献
995.
996.
997.
James D. Nicholson Adam C. Puche Yan Guo Daniel Weinreich Bernard J. Slater Steven L. Bernstein 《PloS one》2012,7(12)
Few clinically effective approaches reduce CNS-white matter injury. After early in-vivo white matter infarct, NFκB-driven pro-inflammatory signals can amplify a relatively small amount of vascular damage, resulting in progressive endothelial dysfunction to create a severe ischemic lesion. This process can be minimized by 15-deoxy-Δ12,14-prostaglandin J2 (PGJ2), an analog of the metabolically active PGD2 metabolite. We evaluated PGJ2''s effects and mechanisms using rodent anterior ischemic optic neuropathy (rAION); an in vivo white matter ischemia model. PGJ2 administration systemically administered either acutely or 5 hours post-insult results in significant neuroprotection, with stereologic evaluation showing improved neuronal survival 30 days post-infarct. Quantitative capillary vascular analysis reveals that PGJ2 improves perfusion at 1 day post-infarct by reducing tissue edema. Our results suggest that PGJ2 acts by reducing NFκB signaling through preventing p65 nuclear localization and inhibiting inflammatory gene expression. Importantly, PGJ2 showed no in vivo toxicity structurally as measured by optic nerve (ON) myelin thickness, functionally by ON-compound action potentials, on a cellular basis by oligodendrocyte precursor survival or changes in ON-myelin gene expression. PGJ2 may be a clinically useful neuroprotective agent for ON and other CNS infarcts involving white matter, with mechanisms of action enabling effective treatment beyond the currently considered maximal time for intervention. 相似文献
998.
Ecology of juvenile grouse during the transition to adulthood 总被引:1,自引:0,他引:1
999.
Michael J. Ingleson 《Inorganica chimica acta》2005,358(5):1571-1580
Cage decomposition products of the highly methylated, weakly coordinating, carborane anion [1-H-closo-CB11Me11]− are described. These arise both from well-defined metal complexes of [1-H-closo-CB11Me11]− that already have BCH3?[M] interactions and from attempts to partner this anion with other metal centres. In all cases the decomposition results in B-CH3 bond cleavage and solvent activation to form products with B-aryl or B-Cl vertices. 相似文献
1000.
Lynn V. Dicks Hugh L. Wright Joscelyne E. Ashpole James Hutchison Caitlin G. McCormack Barbara Livoreil Klaus Peter Zulka William J. Sutherland 《Biodiversity and Conservation》2016,25(7):1383-1399
This paper documents an exercise to synthesize and assess the best available scientific knowledge on the effectiveness of different farm practices at enhancing natural pest regulation in agriculture. It demonstrates a novel combination of three approaches to evidence synthesis—systematic literature search, collated synopsis and evidence assessment using an expert panel. These approaches follow a logical sequence moving from a large volume of disparate evidence to a simple, easily understandable answer for use in policy or practice. The example of natural pest regulation in agriculture was selected as a case study within two independent science-policy interface projects, one European and one British. A third funder, a private business, supported the final stage to translate the synthesized findings into a useful, simplified output for agronomists. As a whole, the case study showcases how a network of scientific knowledge holders and knowledge users can work together to improve the use of science in policy and practice. The process identified five practices with good evidence of a benefit to natural pest regulation, with the most beneficial being ‘Combine trap and repellent crops in a push–pull system’. It highlights knowledge gaps, or potential research priorities, by showing practices considered important by stakeholders for which there is not enough evidence to make an assessment of effects on natural pest regulation, including ‘Alter the timing of pesticide application.’ Finally, the process identifies several important practices where the volume of evidence of effects on natural pest regulation was too large (>300 experimental studies) to be summarised with the resources available, and for which focused systematic reviews may be the best approach. These very well studied practices include ‘Reduce tillage’ and ‘Plant more than one crop per field’. 相似文献