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31.
32.
Fingerprints of global warming on wild animals and plants 总被引:102,自引:0,他引:102
Over the past 100 years, the global average temperature has increased by approximately 0.6 degrees C and is projected to continue to rise at a rapid rate. Although species have responded to climatic changes throughout their evolutionary history, a primary concern for wild species and their ecosystems is this rapid rate of change. We gathered information on species and global warming from 143 studies for our meta-analyses. These analyses reveal a consistent temperature-related shift, or 'fingerprint', in species ranging from molluscs to mammals and from grasses to trees. Indeed, more than 80% of the species that show changes are shifting in the direction expected on the basis of known physiological constraints of species. Consequently, the balance of evidence from these studies strongly suggests that a significant impact of global warming is already discernible in animal and plant populations. The synergism of rapid temperature rise and other stresses, in particular habitat destruction, could easily disrupt the connectedness among species and lead to a reformulation of species communities, reflecting differential changes in species, and to numerous extirpations and possibly extinctions. 相似文献
33.
LI Baoping ZHAO Jianxin Kenneth D. Collerson & Alan Greig Advanced Centre for Queensland University Isotope Research Excel-lence 《科学通报(英文版)》2003,48(12):1219-1224
Chemical analysis plays a significant role in the study of ancient ceramics[1,2]. Most ancient Chinese kilns used clays mined from the local areas and differences in the geochemistry and mineralogy of these raw materials may be expected. The chemical composition of ceramics may also be influenced by production techniques, such as processing by washing and mixing of different sorts of raw materials. These may also vary from kiln to kiln and even change over time. Thus the raw materials and pro… 相似文献
34.
The exocyst complex is required for targeting of Glut4 to the plasma membrane by insulin 总被引:20,自引:0,他引:20
Insulin stimulates glucose transport by promoting exocytosis of the glucose transporter Glut4 (refs 1, 2). The dynamic processes involved in the trafficking of Glut4-containing vesicles, and in their targeting, docking and fusion at the plasma membrane, as well as the signalling processes that govern these events, are not well understood. We recently described tyrosine-phosphorylation events restricted to subdomains of the plasma membrane that result in activation of the G protein TC10 (refs 3, 4). Here we show that TC10 interacts with one of the components of the exocyst complex, Exo70. Exo70 translocates to the plasma membrane in response to insulin through the activation of TC10, where it assembles a multiprotein complex that includes Sec6 and Sec8. Overexpression of an Exo70 mutant blocked insulin-stimulated glucose uptake, but not the trafficking of Glut4 to the plasma membrane. However, this mutant did block the extracellular exposure of the Glut4 protein. So, the exocyst might have a crucial role in the targeting of the Glut4 vesicle to the plasma membrane, perhaps directing the vesicle to the precise site of fusion. 相似文献
35.
ZHANG Jie Yang Ke TAN DeYong ZENG JunYing Alan FINE 《科学通报(英文版)》2007,52(16):2210-2215
Constitutively expressed Fas ligand (FasL) in several distinct epithelial cell types appears to protect tissues by inducing apoptosis of Fas immune cells during inflammatory reactions. To study the rela-tionship of FasL and inflammation process in cornea,we examined the effects of inflammatory cytokine IL-1β on the FasL production,expression and cytotoxic function in corneal endothelial cells. In this paper,we demonstrate that IL-1β inhibits the FasL production and expression in corneal endothelial cells. The promoter activities of FasL in these cells are reduced by IL-1β in a dose-dependent manner. Finally,we also find that IL-1β block the cytotoxic effects of FasL derived from corneal endothelial cells to the Fas target cells. These data support the view that FasL derived from corneal endothelial cells modulate inflammation within cornea. 相似文献
36.
Size, structure, and habitat characteristics were studied in three populations of Braya humilis var. humilis (C. A. Meyer) Robins, in Gray & Wats. (Brassicaceae), a small, herbaceous perennial of the alpine tundra in central Colorado. There was a significant association between numbers of reproductive, juvenile, and seedling individuals and population location. Plant size within reproductive, juvenile, and seedling size classes varied significantly among three populations. Plots containing Braya had significantly lower total plant cover, a different set of dominant plant species, more rock, bare ground, and less litter than plots without Braya . Braya appears to be restricted to calcareous substrates that experience a moderate level of disturbance, such as solifluction lobes and abandoned roads. Populations are small despite the existence of much potential habitat. Population studies are necessary for active conservation management of Braya . 相似文献
37.
Repair of wounds usually results in restoration of organ function, even if suboptimal. However, in a minority of situations,
the healing process leads to significant scarring that hampers homeostasis and leaves the tissue compromised. This scar is
characterized by an excess of matrix deposition that remains poorly organized and weakened. While we know much of the early
stages of the repair process, the transition to wound resolution that limits scar formation is poorly understood. This is
particularly true of the inducers of scar formation. Here, we present a hypothesis that it is the matrix itself that is a
primary driver of scar, rather than being simply the result of other cellular dysregulations. 相似文献
38.
39.
A.邦迪 《国外科技新书评介》2007,(2):21-22
本书是《剑桥理论计算科学专论》丛书的第56卷。自从20世纪50年代起,自动化理论证明成为一个活跃的研究领域。在该领域中的研究人员开始着手处理类似人类的自动化推理。在20世纪60年代和70年代,人们对自动化理论证明的兴趣增加了,这是由于理论进展的驱动。例如归纳的开发以及对程序验证的兴趣增加。 相似文献
40.
Scott RH Douglas J Baskcomb L Huxter N Barker K Hanks S Craft A Gerrard M Kohler JA Levitt GA Picton S Pizer B Ronghe MD Williams D;Factors Associated with Childhood Tumours 《Nature genetics》2008,40(11):1329-1334
Constitutional abnormalities at the imprinted 11p15 growth regulatory region cause syndromes characterized by disordered growth, some of which include a risk of Wilms tumor. We explored their possible contribution to nonsyndromic Wilms tumor and identified constitutional 11p15 abnormalities in genomic lymphocyte DNA from 13 of 437 individuals (3%) with sporadic Wilms tumor without features of growth disorders, including 12% of bilateral cases (P = 0.001) and in one familial Wilms tumor pedigree. No abnormality was detected in 220 controls (P = 0.006). Abnormalities identified included H19 DMR epimutations, uniparental disomy 11p15 and H19 DMR imprinting center mutations (one microinsertion and one microdeletion), thus identifying microinsertion as a new class of imprinting center mutation. Our data identify constitutional 11p15 defects as one of the most common known causes of Wilms tumor, provide mechanistic insights into imprinting disruption and reveal clinically important epigenotype-phenotype associations. The impact on clinical management dictates that constitutional 11p15 analysis should be considered in all individuals with Wilms tumor. 相似文献