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排序方式: 共有902条查询结果,搜索用时 15 毫秒
81.
82.
Sundareshwar PV Murtugudde R Srinivasan G Singh S Ramesh KJ Ramesh R Verma SB Agarwal D Baldocchi D Baru CK Baruah KK Chowdhury GR Dadhwal VK Dutt CB Fuentes J Gupta PK Hargrove WW Howard M Jha CS Lal S Michener WK Mitra AP Morris JT Myneni RR Naja M Nemani R Purvaja R Raha S Vanan SK Sharma M Subramaniam A Sukumar R Twilley RR Zimmerman PR 《Science (New York, N.Y.)》2007,316(5822):204-205
83.
Howard LO 《Science (New York, N.Y.)》1915,41(1052):312-315
84.
Chen J de Felipe KS Clarke M Lu H Anderson OR Segal G Shuman HA 《Science (New York, N.Y.)》2004,303(5662):1358-1361
Legionella pneumophila, the bacterial agent of legionnaires' disease, replicates intracellularly within a specialized vacuole of mammalian and protozoan host cells. Little is known about the specialized vacuole except that the Icm/Dot type IV secretion system is essential for its formation and maintenance. The Legionella genome database contains two open reading frames encoding polypeptides (LepA and LepB) with predicted coiled-coil regions and weak homology to SNAREs; these are delivered to host cells by an Icm/Dot-dependent mechanism. Analysis of mutant strains suggests that the Lep proteins may enable the Legionella to commandeer a protozoan exocytic pathway for dissemination of the pathogen. 相似文献
85.
Genetic structure of human populations 总被引:1,自引:0,他引:1
Rosenberg NA Pritchard JK Weber JL Cann HM Kidd KK Zhivotovsky LA Feldman MW 《Science (New York, N.Y.)》2002,298(5602):2381-2385
We studied human population structure using genotypes at 377 autosomal microsatellite loci in 1056 individuals from 52 populations. Within-population differences among individuals account for 93 to 95% of genetic variation; differences among major groups constitute only 3 to 5%. Nevertheless, without using prior information about the origins of individuals, we identified six main genetic clusters, five of which correspond to major geographic regions, and subclusters that often correspond to individual populations. General agreement of genetic and predefined populations suggests that self-reported ancestry can facilitate assessments of epidemiological risks but does not obviate the need to use genetic information in genetic association studies. 相似文献
86.
Chien M Morozova I Shi S Sheng H Chen J Gomez SM Asamani G Hill K Nuara J Feder M Rineer J Greenberg JJ Steshenko V Park SH Zhao B Teplitskaya E Edwards JR Pampou S Georghiou A Chou IC Iannuccilli W Ulz ME Kim DH Geringer-Sameth A Goldsberry C Morozov P Fischer SG Segal G Qu X Rzhetsky A Zhang P Cayanis E De Jong PJ Ju J Kalachikov S Shuman HA Russo JJ 《Science (New York, N.Y.)》2004,305(5692):1966-1968
We present the genomic sequence of Legionella pneumophila, the bacterial agent of Legionnaires' disease, a potentially fatal pneumonia acquired from aerosolized contaminated fresh water. The genome includes a 45-kilobase pair element that can exist in chromosomal and episomal forms, selective expansions of important gene families, genes for unexpected metabolic pathways, and previously unknown candidate virulence determinants. We highlight the genes that may account for Legionella's ability to survive in protozoa, mammalian macrophages, and inhospitable environmental niches and that may define new therapeutic targets. 相似文献
87.
Einsle O Tezcan FA Andrade SL Schmid B Yoshida M Howard JB Rees DC 《Science (New York, N.Y.)》2002,297(5587):1696-1700
A high-resolution crystallographic analysis of the nitrogenase MoFe-protein reveals a previously unrecognized ligand coordinated to six iron atoms in the center of the catalytically essential FeMo-cofactor. The electron density for this ligand is masked in structures with resolutions lower than 1.55 angstroms, owing to Fourier series termination ripples from the surrounding iron and sulfur atoms in the cofactor. The central atom completes an approximate tetrahedral coordination for the six iron atoms, instead of the trigonal coordination proposed on the basis of lower resolution structures. The crystallographic refinement at 1.16 angstrom resolution is consistent with this newly detected component being a light element, most plausibly nitrogen. The presence of a nitrogen atom in the cofactor would have important implications for the mechanism of dinitrogen reduction by nitrogenase. 相似文献
88.
Armstead I Donnison I Aubry S Harper J Hörtensteiner S James C Mani J Moffet M Ougham H Roberts L Thomas A Weeden N Thomas H King I 《Science (New York, N.Y.)》2007,315(5808):73
A key gene involved in plant senescence, mutations of which partially disable chlorophyll catabolism and confer stay-green leaf and cotyledon phenotypes, has been identified in Pisum sativum, Arabidopsis thaliana, and Festuca pratensis by using classical and molecular genetics and comparative genomics. A stay-green locus in F. pratensis is syntenically equivalent to a similar stay-green locus on rice chromosome 9. Functional testing in Arabidopsis of a homolog of the rice candidate gene revealed (i) senescence-associated gene expression and (ii) a stay-green phenotype after RNA interference silencing. Genetic mapping in pea demonstrated cosegregation with the yellow/green cotyledon polymorphism (I/i) first reported by Gregor Mendel in 1866. 相似文献
89.
Disseminated infection with Histoplasma capsulatum was diagnosed in a 7-yr-old female Bengal tiger (Panthera tigris). Clinical signs were nonspecific with the exception of brief periods of tachypnea for 5 days prior to death. H. capsulatum organisms were found in the lungs, tracheobronchial lymph nodes, and liver. Diagnosis was confirmed by tracheal wash, urine H. capsulatum enzyme immunoassay, and necropsy results. This report represents the first published account of disseminated histoplasmosis in a tiger. 相似文献
90.
D. C. Rennie V. P. Manolii T. Cao S. F. Hwang R. J. Howard S. E. Strelkov 《Plant pathology》2011,60(5):811-819
Using quantitative PCR, DNA of Plasmodiophora brassicae, the causal agent of clubroot, was detected and quantified on canola, pea and wheat seeds, as well as on potato tubers, all harvested from clubroot‐infested fields in Alberta, Canada. Quantifiable levels of infestation were found on seven of the 46 samples analysed, and ranged from <1·0 × 103 to 3·4 × 104 resting spores per 10 g seeds; the vast majority (80–100%) of resting spores on these samples were viable, as determined by Evan’s blue vital staining. However, the levels of infestation found were generally lower than that required to cause consistent clubroot symptoms in greenhouse plant bioassays. While the occurrence of P. brassicae resting spores on seeds and tubers harvested from clubroot‐infested fields suggests that seedborne dissemination of this pathogen is possible, practices such as commercial seed cleaning may be sufficient to effectively mitigate this risk. 相似文献