Epidermal viral immunity induced by CD8alpha+ dendritic cells but not by Langerhans cells     

Allan RS  Smith CM  Belz GT  van Lint AL  Wakim LM  Heath WR  Carbone FR 《Science (New York, N.Y.)》2003,301(5641):1925-1928

The classical paradigm for dendritic cell function derives from the study of Langerhans cells, which predominate within skin epidermis. After an encounter with foreign agents, Langerhans cells are thought to migrate to draining lymph nodes, where they initiate T cell priming. Contrary to this, we show here that infection of murine epidermis by herpes simplex virus did not result in the priming of virus-specific cytotoxic T lymphocytes by Langerhans cells. Rather, the priming response required a distinct CD8alpha+ dendritic cell subset. Thus, the traditional view of Langerhans cells in epidermal immunity needs to be revisited to accommodate a requirement for other dendritic cells in this response.  相似文献   

Uptake of an amino acid by ectomycorrhizal fungi in a boreal forest     

Kathleen K. Treseder  Claudia I. Czimczik  Susan E. Trumbore  Steven D. Allison 《Soil biology & biochemistry》2008,40(7):1964-1966

We assessed the degree to which ectomycorrhizal fungi exploit organic nitrogen in situ. In an Alaskan boreal forest, we identified pairs of sporocarps from five taxa of ectomycorrhizal fungi. We added ¹³C-labeled alanine to the soil surrounding one sporocarp within each pair; the second served as an unlabeled control. Peak rates of ¹³C-respiration from alanine were higher in the labeled sporocarp plots than the controls, indicating that the ¹³C-alanine was detectably respired from the soil. “Reference” plots adjacent to the sporocarps served as an indication of background ¹³C-respiration rates released by the soil community as a whole. Ectomycorrhizal sporocarps displayed higher ¹³C-respiration rates than their reference plots. Thus, the sporocarps and associated mycorrhizal mycelium appeared to contribute significantly to the release of alanine-derived ¹³CO₂, confirming the hypothesis that ectomycorrhizal fungi may access soil amino acid pools under natural conditions.  相似文献   

Veterinary academe evaluates animal use in education     

Rezendes A 《Journal of the American Veterinary Medical Association》2006,228(10):1481-1482

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Photosynthetic light use efficiency of three biomes across an east–west continental-scale transect in Canada     

Christopher R. Schwalm  T. Andrew Black  Brian D. Amiro  M. Altaf Arain  Alan G. Barr  Charles P.-A. Bourque  Allison L. Dunn  Larry B. Flanagan  Marc-Andr Giasson  Peter M. Lafleur  Hank A. Margolis  J. Harry McCaughey  Alberto L. Orchansky  Steve C. Wofsy 《Agricultural and Forest Meteorology》2006,140(1-4):269

Light use efficiency (LUE) is used widely in scaling and modeling contexts. However, the variation and biophysical controls on LUE remain poorly documented. Networks of eddy covariance (EC) towers offer an opportunity to quantify _g, the ratio of P, gross primary productivity, to Q_a, absorbed photosynthetically active radiation (PAR), across climate zones and vegetation types. Using data from the Fluxnet Canada Research Network (n = 24 sites) in 2004, we examined the relationship between daily and yearly _g, driving variables, and site characteristics on a site-specific and plant functional type (PFT) basis using tree regression and linear regression. Data were available for three biomes: grassland, forest, and wetland. Yearly _g values ranged from 0.1 to 3.6 g C MJ⁻¹ Q_a overall. Daily _g was highest in the grassland (daily median ± interquartile range: 3.68 ± 1.98 g C MJ⁻¹ Q_a), intermediate in the forested biome (0.84 ± 0.82 g C MJ⁻¹ Q_a), and lowest for the wetlands (0.65 ± 0.54 g C MJ⁻¹ Q_a). The most important biophysical controls were light and temperature, to the exclusion of water-related variables: a homogeneity of slopes model explained c. 75% of the variation in daily _g. For a subset of sites with diffuse PAR data, the ratio of diffuse to total PAR, a proxy for cloudiness, was a key predictor. On the yearly time scale, _g was related to leaf area index and mean annual temperature. Aggregating to PFTs did not show functional convergence within any PFT except for the three wetland sites and the Picea mariana toposequence at the daily time step, and when using the Köppen climate classification on a yearly time step. The general lack of conservative daily _g behavior within PFTs suggests that PFT-based parameterizations are inappropriate, especially when applied on shorter temporal scales.  相似文献   

The sand seas of Titan: Cassini RADAR observations of longitudinal dunes   总被引：1，自引：0，他引：1  

Lorenz RD  Wall S  Radebaugh J  Boubin G  Reffet E  Janssen M  Stofan E  Lopes R  Kirk R  Elachi C  Lunine J  Mitchell K  Paganelli F  Soderblom L  Wood C  Wye L  Zebker H  Anderson Y  Ostro S  Allison M  Boehmer R  Callahan P  Encrenaz P  Ori GG  Francescetti G  Gim Y  Hamilton G  Hensley S  Johnson W  Kelleher K  Muhleman D  Picardi G  Posa F  Roth L  Seu R  Shaffer S  Stiles B  Vetrella S  Flamini E  West R 《Science (New York, N.Y.)》2006,312(5774):724-727

The most recent Cassini RADAR images of Titan show widespread regions (up to 1500 kilometers by 200 kilometers) of near-parallel radar-dark linear features that appear to be seas of longitudinal dunes similar to those seen in the Namib desert on Earth. The Ku-band (2.17-centimeter wavelength) images show approximately 100-meter ridges consistent with duneforms and reveal flow interactions with underlying hills. The distribution and orientation of the dunes support a model of fluctuating surface winds of approximately 0.5 meter per second resulting from the combination of an eastward flow with a variable tidal wind. The existence of dunes also requires geological processes that create sand-sized (100- to 300-micrometer) particulates and a lack of persistent equatorial surface liquids to act as sand traps.  相似文献   

Disseminated peripheral neuroblastoma in a Rhodesian Ridgeback dog          下载免费PDF全文

RW Cook  LA Abraham  CI McCowan 《Australian veterinary journal》2017,95(4):129-133

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The occurrence of wild cotton <Emphasis Type="Italic">Gossypium mustelinum</Emphasis> Miers ex Watt populations in the coast of Pernambuco,Northeastern Brazil     

Edson Ferreira da Silva  Luiz Sergio Costa Duarte Filho  Ana Kelly dos Santos Maia  Allison Vieira da Silva  Ana Carolina Borges Lins e Silva 《Genetic Resources and Crop Evolution》2018,65(6):1551-1557

In this study, we describe three populations of the wild cotton Gossypium mustelinum Miers ex Watt in the coastal plain to the north of the State of Pernambuco, Northeast Brazil. These populations occur in urban areas in current expansion and under imminent risks of extinction, due to land use changes for house constructions. Distances between these new occurrences and the populations already mapped in the Northeast semiarid Caatinga (Rio Grande do Norte, Ceará, and Bahia) range from approximately 270–950 km. Besides distant, the populations on the coastal plain of Pernambuco also occur in very distinct climatic and edaphic conditions. Aiming at allowing the ex situ conservation of these genetic resources, branches of 66 plants were collected, propagated by the asexual breeding method cutting to regenerate an accession of each plant. These now constitute a germplasm collection in the Department of Agronomy of the Federal Rural University of Pernambuco (UFRPE), in Recife, Pernambuco, Brazil.  相似文献   

Gold nanoelectrodes of varied size: transition to molecule-like charging   总被引：1，自引：0，他引：1  

S Chen  RS Ingram  MJ Hostetler  JJ Pietron  RW Murray  TG Schaaff  JT Khoury  MM Alvarez  RL Whetten 《Science (New York, N.Y.)》1998,280(5372):2098-2101

A transition from metal-like double-layer capacitive charging to redox-like charging was observed in electrochemical ensemble Coulomb staircase experiments on solutions of gold nanoparticles of varied core size. The monodisperse gold nanoparticles are stabilized by short-chain alkanethiolate monolayers and have 8 to 38 kilodaltons core mass (1.1 to 1.9 nanometers in diameter). Larger cores display Coulomb staircase responses consistent with double-layer charging of metal-electrolyte interfaces, whereas smaller core nanoparticles exhibit redox chemical character, including a large central gap. The change in behavior is consistent with new near-infrared spectroscopic data showing an emerging gap between the highest occupied and lowest unoccupied orbitals of 0.4 to 0.9 electron volt.  相似文献