Cleavage of proBDNF by tPA/plasmin is essential for long-term hippocampal plasticity     

Pang PT  Teng HK  Zaitsev E  Woo NT  Sakata K  Zhen S  Teng KK  Yung WH  Hempstead BL  Lu B 《Science (New York, N.Y.)》2004,306(5695):487-491

Long-term memory is thought to be mediated by protein synthesis-dependent, late-phase long-term potentiation (L-LTP). Two secretory proteins, tissue plasminogen activator (tPA) and brain-derived neurotrophic factor (BDNF), have been implicated in this process, but their relationship is unclear. Here we report that tPA, by activating the extracellular protease plasmin, converts the precursor proBDNF to the mature BDNF (mBDNF), and that such conversion is critical for L-LTP expression in mouse hippocampus. Moreover, application of mBDNF is sufficient to rescue L-LTP when protein synthesis is inhibited, which suggests that mBDNF is a key protein synthesis product for L-LTP expression.  相似文献   

The Water Dipole Moment in Water Clusters     

JK Gregory  DC Clary  K Liu  MG Brown  RJ Saykally 《Science (New York, N.Y.)》1997,275(5301):814-817

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Projecting impacts of human disturbances to inform conservation planning and management in a dryland forest landscape     

A.C. Newton  C. Echeverría  E. Cantarello  G. Bolados 《Biological conservation》2011,(7):1949-1960

Systematic approaches to conservation planning and management require spatially explicit information on the dynamics of multiple disturbance processes, but progress in providing such information has been limited to date. Here we examine the use of a spatially explicit model of forest dynamics (LANDIS-II), incorporating a range of ecological processes, to examine the impacts of different types of disturbance on a dryland forest landscape in Central Chile. The model was parameterized using spatial data and results of a field survey, in which 21 native tree species were recorded, and one invasive exotic (Acacia dealbata). Seven disturbance scenarios were simulated, with different combinations of fire, browsing and tree cutting. Model results indicated relatively little impact of disturbance on forest cover but substantial differences in forest structure, with relatively old-growth forest stands (>120 years old) being virtually eliminated from the landscape in scenarios with both browsing and cutting. Tree species richness tended to be lower in those scenarios without disturbance, highlighting potential trade-offs between forest structure and species richness. Spread of A. dealbata was projected only to occur in the presence of fire when combined with browsing and/or cutting. These interactive effects of different forms of disturbance illustrate the value of process-based modeling approaches for exploring the spatial dynamics of multiple disturbance processes, but highlight the difficulty of identifying an optimum disturbance regime that would enable conservation objectives to be achieved. It is suggested that process-based models should form part of an analytical ‘toolkit’ to support the practical implementation of systematic conservation planning approaches.  相似文献   

Frequency of equine laminitis: a systematic review with quality appraisal of published evidence     

Wylie CE  Collins SN  Verheyen KL  Richard Newton J 《Veterinary journal (London, England : 1997)》2011,189(3):248-256

Equine laminitis is a highly debilitating disease of the foot. Despite its perceived importance, epidemiological characteristics are poorly understood and the true frequency of the disease remains unclear. The objective of this study was to retrospectively assess previous research to identify publications which provide the best evidence of the frequency of naturally-occurring equine laminitis. A systematic review of English language publications was conducted using MEDLINE (1950–2010), CAB Direct (1910–2010) and IVIS (1997–2010). Additional publications were included by searching bibliographies. Search terms included laminitis, equine, frequency, prevalence and incidence. Studies that allowed frequency estimations to be made for naturally-occurring equine laminitis were included. Information was extracted using predefined data fields, including 13 study quality indicators.Sixty-nine publications were appraised. Ten were considered to provide the most reliable information, estimating the frequency of equine laminitis ranging from 1.5% to 34%. Previous publications estimating laminitis frequency were generally poor quality. Laminitis frequency varied across publications however the publications included in this review focussed on many of the different underlying laminitis aetiologies and comparison of the frequencies between groups would be inappropriate. High-quality evidence-based studies are needed to estimate the true disease frequency in different equine populations.  相似文献   

Response of the fauna of a grassland soil to doubling of atmospheric carbon dioxide concentration     

G. W. Yeates  K. R. Tate  P. C. D. Newton 《Biology and Fertility of Soils》1997,25(3):307-315

The effects of elevated CO₂ on rhizosphere processes, including the response of soil faunal populations and community structure, have so far received little attention. We report on significant responses in the soil fauna of ryegrass/white clover swards to both increasing CO₂ from 350 to 750 μl · l^–1 and, to a period of 60 days when some of the turves were subject to drought, in a controlled climate growth room experiment. The nematodes which increased were predominantly Enoplia, including dorylaimids, alaimids and trichodorids. This accords with both the doubling of Alaimus under elevated CO₂ conditions reported in a similar experiment and with the common association of Enoplia with less disturbed habitats. The most marked decrease was in the bacterial-feeding Rhabditis (Secernentea). The increase in omnivorous and predacious nematodes may have been responsible for the decrease in populations of bacterial-feeding nematodes. However, in contrast to their standing crops, the turnover rate of bacterial-feeding nematodes and soil microbial biomass probably increased as a result of increased grazing by these omnivorous and predacious nematodes. Increases in earthworm and enchytraeid populations were related to increased below-ground productivity reported for the same trial. Received: 30 September 1996  相似文献   

The practical use of semiparametric models in field trials     

Maria Durban  Christine A. Hackett  James W. McNicol  Adrian C. Newton  William T. B. Thomas  Iain D. Currie 《Journal of Agricultural, Biological & Environmental Statistics》2003,8(1):48-66

This article examines the practical use of semiparametric models in the analysis of field trials—that is, models with parameterized treatment effects and additive terms derived by a data-driven approach using a locally weighted running line smoother (loess). We discuss graphical methods to identify spatial structure in the data and model selection procedures to choose the degree of smoothing. Once the spatial part of the model has been chosen, hypotheses about the treatment effects may be tested. Semiparametric models are used to analyze two barley field trials exhibiting spatial trends. The first has a single experimental treatment and a row-column design. The second has a split-plot design, and we use a semiparametric model which accounts for the randomization at the different strata of this design. We compare the semiparametric analyses with classical analyses of variance and with alternative spatial models. We find that semiparametric models give a good insight into spatial variation in the field and can improve the precision of parameter estimates.  相似文献   

Fenthion poisoning of native birds in southern Queensland     

RA McKENZIE  AEL LANHAM  JD TAYLOR  JA GIBSON  RJ PIERCE 《Australian veterinary journal》1996,74(4):321-323

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SHORT CONTRIBUTION     

RJ SUTER 《Australian veterinary journal》2002,80(5):282-282

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The effect of combinations of anthelmintics on parasite populations in sheep     

PJ WALLER  RJ DOBSON  KG HAUGHEY 《Australian veterinary journal》1990,67(4):138-140

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A RULE FOR THE INTERPRETATION OF MELTING POINT DIAGRAMS     

Newton RF 《Science (New York, N.Y.)》1934,79(2049):321-322

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