Monitoring of blood vessels and tissues by a population of monocytes with patrolling behavior     

Auffray C  Fogg D  Garfa M  Elain G  Join-Lambert O  Kayal S  Sarnacki S  Cumano A  Lauvau G  Geissmann F 《Science (New York, N.Y.)》2007,317(5838):666-670

The cellular immune response to tissue damage and infection requires the recruitment of blood leukocytes. This process is mediated through a classical multistep mechanism, which involves transient rolling on the endothelium and recognition of inflammation followed by extravasation. We have shown, by direct examination of blood monocyte functions in vivo, that a subset of monocytes patrols healthy tissues through long-range crawling on the resting endothelium. This patrolling behavior depended on the integrin LFA-1 and the chemokine receptor CX(3)CR1 and was required for rapid tissue invasion at the site of an infection by this "resident" monocyte population, which initiated an early immune response and differentiated into macrophages.  相似文献   

Melanopsin is required for non-image-forming photic responses in blind mice     

Panda S  Provencio I  Tu DC  Pires SS  Rollag MD  Castrucci AM  Pletcher MT  Sato TK  Wiltshire T  Andahazy M  Kay SA  Van Gelder RN  Hogenesch JB 《Science (New York, N.Y.)》2003,301(5632):525-527

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The global circulation of seasonal influenza A (H3N2) viruses     

Russell CA  Jones TC  Barr IG  Cox NJ  Garten RJ  Gregory V  Gust ID  Hampson AW  Hay AJ  Hurt AC  de Jong JC  Kelso A  Klimov AI  Kageyama T  Komadina N  Lapedes AS  Lin YP  Mosterin A  Obuchi M  Odagiri T  Osterhaus AD  Rimmelzwaan GF  Shaw MW  Skepner E  Stohr K  Tashiro M  Fouchier RA  Smith DJ 《Science (New York, N.Y.)》2008,320(5874):340-346

Antigenic and genetic analysis of the hemagglutinin of approximately 13,000 human influenza A (H3N2) viruses from six continents during 2002-2007 revealed that there was continuous circulation in east and Southeast Asia (E-SE Asia) via a region-wide network of temporally overlapping epidemics and that epidemics in the temperate regions were seeded from this network each year. Seed strains generally first reached Oceania, North America, and Europe, and later South America. This evidence suggests that once A (H3N2) viruses leave E-SE Asia, they are unlikely to contribute to long-term viral evolution. If the trends observed during this period are an accurate representation of overall patterns of spread, then the antigenic characteristics of A (H3N2) viruses outside E-SE Asia may be forecast each year based on surveillance within E-SE Asia, with consequent improvements to vaccine strain selection.  相似文献   

Wind as a long-distance dispersal vehicle in the Southern Hemisphere     

Muñoz J  Felicísimo AM  Cabezas F  Burgaz AR  Martínez I 《Science (New York, N.Y.)》2004,304(5674):1144-1147

Anisotropic (direction-dependent) long-distance dispersal (LDD) by wind has been invoked to explain the strong floristic affinities shared among landmasses in the Southern Hemisphere. Its contribution has not yet been systematically tested because of the previous lack of global data on winds. We used global winds coverage from the National Aeronautics and Space Administration SeaWinds scatterometer to test whether floristic similarities of Southern Hemisphere moss, liverwort, lichen, and pteridophyte floras conform better with (i) the anisotropic LDD hypothesis, which predicts that connection by "wind highways" increases floristic similarities, or (ii) a direction-independent LDD hypothesis, which predicts that floristic similarities among sites increase with geographic proximity. We found a stronger correlation of floristic similarities with wind connectivity than with geographic proximities, which supports the idea that wind is a dispersal vehicle for many organisms in the Southern Hemisphere.  相似文献   

Rural development in the time of deconstructing the one-party political systems and centrally planned economies     

Ana Barbic 《Agriculture and Human Values》1993,10(1):40-51

The political developments in post-socialist countries are taken as a general frame for discussing rural development in the transition from centrally planned to market economies. Rural communities and agriculture in post-socialist countries are facing major problems related to decollectivization of property, the stimulation of effective private agricultural units, and the building up of integrated rural communities and their local autonomy. After presenting the developments in Slovenia in detail, the author comes to the conclusion that no foreign/western development model can be literally applied to any post-socialist state. These nations must define their own goals and formulate the strategies to reach them based on the analysis of their specific situations, and in doing this they must engage their own scientists/professionals and take foreign experts only as occasional advisors.Ana Barbic is Professor of Sociology and Political Science at the Edvar Kardeij University of Ljublijana, Slovenia. Dr. Barbic has carried out research and written on topics including family farming, the structure of agriculture, farm self-management, and the role of women in farming. She is the author of numerous papers, which have been published in several languages. She is vice-president of the European Society of Rural Sociology.  相似文献   

Scientists and the Venezuelan crisis     

Jaffe K  Di Polo R  Cardier J  Rios R  Utrera R  Rodriguez M  Zoppi LB  Rojas AM  Ponte A  Scharifker B  Bemporad M;Board of Directors  Venezuelan Association for the Advancement of Science  Caracas 《Science (New York, N.Y.)》2003,299(5610):1184

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Amplification of acetylcholine-binding catenanes from dynamic combinatorial libraries     

Lam RT  Belenguer A  Roberts SL  Naumann C  Jarrosson T  Otto S  Sanders JK 《Science (New York, N.Y.)》2005,308(5722):667-669

Directed chemical synthesis can produce a vast range of molecular structures, but the intended product must be known at the outset. In contrast, evolution in nature can lead to efficient receptors and catalysts whose structures defy prediction. To access such unpredictable structures, we prepared dynamic combinatorial libraries in which reversibly binding building blocks assemble around a receptor target. We selected for an acetylcholine receptor by adding the neurotransmitter to solutions of dipeptide hydrazones [proline-phenylalanine or proline-(cyclohexyl)alanine], which reversibly combine through hydrazone linkages. At thermodynamic equilibrium, the dominant receptor structure was an elaborate [2]-catenane consisting of two interlocked macrocyclic trimers. This complex receptor with a 100 nM affinity for acetylcholine could be isolated on a preparative scale in 67% yield.  相似文献   

James Aronson, Jo?o S. Pereira and Juli G. Pausas (eds): Cork oak woodlands on the edge: ecology, adaptive management, and restoration     

Ana Firmino 《Landscape Ecology》2011,26(1):151-152

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Effect of dextransucrase cellobiose acceptor products on the growth of human gut bacteria     

Ruiz-Matute AI  Brokl M  Sanz ML  Soria AC  Côté GL  Collins ME  Rastall RA 《Journal of agricultural and food chemistry》2011,59(8):3693-3700

The selective fermentation by human gut bacteria of gluco-oligosaccharides obtained from the reaction between the glucosyl group of sucrose and cellobiose, catalyzed by dextransucrases (DSR) from Leuconostoc mesenteroides , has been evaluated. Oligosaccharides were fractionated according to their molecular weight, and their effect on the growth of different bacterial groups was studied. To determine the structure (position and configuration of glycosidic linkages)-function relationship, their properties were compared to those of DSR maltose acceptor products (DSRMal) and of recognized prebiotic carbohydrates (fructo-oligosaccharides, FOS). Cellobiose acceptor products (DSRCel) showed bifidogenic properties similar to those of FOS. However, no significant differences related to molecular weight or isomeric configurations were found for DSRCel and DSRMal products.  相似文献   

The paradox of the conservation of an endangered fish species in a Mediterranean region under agricultural intensification     

J. Jesús Casas  Juan S. Sánchez-Oliver  Ana Sanz  Miriam Furné  Cristina Trenzado  Melchor Juan  Mariano Paracuellos  María D. Suárez  Francisca Fuentes  Irene Gallego  Carlos Gil  José J. Ramos-Miras 《Biological conservation》2011,(1):253-262

We studied the relative value of natural habitats, river and coastal wetlands, and artificial habitats, irrigation canal and ponds, for the conservation of an endangered fish, Iberian toothcarp, in its southernmost area of distribution, characterised by agricultural intensification. Our results show that the bulk of the population of the Iberian toothcarp is concentrated in irrigation ponds. Natural habitats sustained null or impoverished subpopulations, and individuals showed signs of low metabolic activity. This coincided with the relatively high habitat quality observed in ponds, particularly those with submerged aquatic vegetation, in contrast with the chronic eutrophication of the coastal lagoons. In spite of a generalised aggressive management in the irrigation system, featured by periodic vegetation clearance, desiccation and biocide treatment, the subpopulation of the Iberian toothcarp thrives in it probably thanks to adequate water quality and to an active path dynamics maintained by connectivity through the canal. Agro-environmental measures are discussed for the improvement of this species conservation in natural and artificial habitats.  相似文献