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131.
Herring CD Raghunathan A Honisch C Patel T Applebee MK Joyce AR Albert TJ Blattner FR van den Boom D Cantor CR Palsson BØ 《Nature genetics》2006,38(12):1406-1412
We applied whole-genome resequencing of Escherichia coli to monitor the acquisition and fixation of mutations that conveyed a selective growth advantage during adaptation to a glycerol-based growth medium. We identified 13 different de novo mutations in five different E. coli strains and monitored their fixation over a 44-d period of adaptation. We obtained proof that the observed spontaneous mutations were responsible for improved fitness by creating single, double and triple site-directed mutants that had growth rates matching those of the evolved strains. The success of this new genome-scale approach indicates that real-time evolution studies will now be practical in a wide variety of contexts. 相似文献
132.
Evidence for complete denitrification in a benthic foraminifer 总被引:2,自引:0,他引:2
Risgaard-Petersen N Langezaal AM Ingvardsen S Schmid MC Jetten MS Op den Camp HJ Derksen JW Piña-Ochoa E Eriksson SP Nielsen LP Revsbech NP Cedhagen T van der Zwaan GJ 《Nature》2006,443(7107):93-96
Benthic foraminifera are unicellular eukaryotes found abundantly in many types of marine sediments. Many species survive and possibly reproduce in anoxic habitats, but sustainable anaerobic metabolism has not been previously described. Here we demonstrate that the foraminifer Globobulimina pseudospinescens accumulates intracellular nitrate stores and that these can be respired to dinitrogen gas. The amounts of nitrate detected are estimated to be sufficient to support respiration for over a month. In a Swedish fjord sediment where G. pseudospinescens is the dominant foraminifer, the intracellular nitrate pool in this species accounted for 20% of the large, cell-bound, nitrate pool present in an oxygen-free zone. Similarly high nitrate concentrations were also detected in foraminifera Nonionella cf. stella and a Stainforthia species, the two dominant benthic taxa occurring within the oxygen minimum zone of the continental shelf off Chile. Given the high abundance of foraminifera in anoxic marine environments, these new findings suggest that foraminifera may play an important role in global nitrogen cycling and indicate that our understanding of the complexity of the marine nitrogen cycle is far from complete. 相似文献
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135.
Unusual high-density and saline aqueous inclusions in ultrahigh pressure metamorphic rocks from Sulu terrane in eastern China 总被引:1,自引:2,他引:1
SHEN Kun ZHANG Zeming A. M. van den Kerkhof XIAO Yilin XU Zhiqin & J. Hoefs . Institute of Geological Sciences of Shandong Jinan China . Institute of Geology CAGS Beijing China . Geoscience Center University Gttingen Gttingen Germany Correspondence should be addressed to Zhang Zeming 《科学通报(英文版)》2003,48(18):2018-2023
Fluid inclusions are the samples of metamorphic fluids trapped during the formation and/or later fractur-ing-resealing processes of metamorphic minerals. The composition and properties of fluid incluisons can reflect the physico-chemical conditions of the fluids during plate subduction and exhuamtion[1]. Ultrahigh pressure (UHP) metamorphic rocks commonly experienced considerable decompression in the course of exhumation process. This has caused departure of the retrograde P-T path of the ro… 相似文献
136.
Schlappa J Wohlfeld K Zhou KJ Mourigal M Haverkort MW Strocov VN Hozoi L Monney C Nishimoto S Singh S Revcolevschi A Caux JS Patthey L Rønnow HM van den Brink J Schmitt T 《Nature》2012,485(7396):82-85
When viewed as an elementary particle, the electron has spin and charge. When binding to the atomic nucleus, it also acquires an angular momentum quantum number corresponding to the quantized atomic orbital it occupies. Even if electrons in solids form bands and delocalize from the nuclei, in Mott insulators they retain their three fundamental quantum numbers: spin, charge and orbital. The hallmark of one-dimensional physics is a breaking up of the elementary electron into its separate degrees of freedom. The separation of the electron into independent quasi-particles that carry either spin (spinons) or charge (holons) was first observed fifteen years ago. Here we report observation of the separation of the orbital degree of freedom (orbiton) using resonant inelastic X-ray scattering on the one-dimensional Mott insulator Sr2CuO3. We resolve an orbiton separating itself from spinons and propagating through the lattice as a distinct quasi-particle with a substantial dispersion in energy over momentum, of about 0.2 electronvolts, over nearly one Brillouin zone. 相似文献
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Enciso-Mora V Broderick P Ma Y Jarrett RF Hjalgrim H Hemminki K van den Berg A Olver B Lloyd A Dobbins SE Lightfoot T van Leeuwen FE Försti A Diepstra A Broeks A Vijayakrishnan J Shield L Lake A Montgomery D Roman E Engert A von Strandmann EP Reiners KS Nolte IM Smedby KE Adami HO Russell NS Glimelius B Hamilton-Dutoit S de Bruin M Ryder LP Molin D Sorensen KM Chang ET Taylor M Cooke R Hofstra R Westers H van Wezel T van Eijk R Ashworth A Rostgaard K Melbye M Swerdlow AJ Houlston RS 《Nature genetics》2010,42(12):1126-1130
To identify susceptibility loci for classical Hodgkin's lymphoma (cHL), we conducted a genome-wide association study of 589 individuals with cHL (cases) and 5,199 controls with validation in four independent samples totaling 2,057 cases and 3,416 controls. We identified three new susceptibility loci at 2p16.1 (rs1432295, REL, odds ratio (OR) = 1.22, combined P = 1.91 × 10(-8)), 8q24.21 (rs2019960, PVT1, OR = 1.33, combined P = 1.26 × 10(-13)) and 10p14 (rs501764, GATA3, OR = 1.25, combined P = 7.05 × 10(-8)). Furthermore, we confirmed the role of the major histocompatibility complex in disease etiology by revealing a strong human leukocyte antigen (HLA) association (rs6903608, OR = 1.70, combined P = 2.84 × 10(-50)). These data provide new insight into the pathogenesis of cHL. 相似文献
140.
Rees MI Harvey K Pearce BR Chung SK Duguid IC Thomas P Beatty S Graham GE Armstrong L Shiang R Abbott KJ Zuberi SM Stephenson JB Owen MJ Tijssen MA van den Maagdenberg AM Smart TG Supplisson S Harvey RJ 《Nature genetics》2006,38(7):801-806
Hyperekplexia is a human neurological disorder characterized by an excessive startle response and is typically caused by missense and nonsense mutations in the gene encoding the inhibitory glycine receptor (GlyR) alpha1 subunit (GLRA1). Genetic heterogeneity has been confirmed in rare sporadic cases, with mutations affecting other postsynaptic glycinergic proteins including the GlyR beta subunit (GLRB), gephyrin (GPHN) and RhoGEF collybistin (ARHGEF9). However, many individuals diagnosed with sporadic hyperekplexia do not carry mutations in these genes. Here we show that missense, nonsense and frameshift mutations in SLC6A5 (ref. 8), encoding the presynaptic glycine transporter 2 (GlyT2), also cause hyperekplexia. Individuals with mutations in SLC6A5 present with hypertonia, an exaggerated startle response to tactile or acoustic stimuli, and life-threatening neonatal apnea episodes. SLC6A5 mutations result in defective subcellular GlyT2 localization, decreased glycine uptake or both, with selected mutations affecting predicted glycine and Na+ binding sites. 相似文献