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排序方式: 共有1732条查询结果,搜索用时 15 毫秒
881.
Gerken T Girard CA Tung YC Webby CJ Saudek V Hewitson KS Yeo GS McDonough MA Cunliffe S McNeill LA Galvanovskis J Rorsman P Robins P Prieur X Coll AP Ma M Jovanovic Z Farooqi IS Sedgwick B Barroso I Lindahl T Ponting CP Ashcroft FM O'Rahilly S Schofield CJ 《Science (New York, N.Y.)》2007,318(5855):1469-1472
Variants in the FTO (fat mass and obesity associated) gene are associated with increased body mass index in humans. Here, we show by bioinformatics analysis that FTO shares sequence motifs with Fe(II)- and 2-oxoglutarate-dependent oxygenases. We find that recombinant murine Fto catalyzes the Fe(II)- and 2OG-dependent demethylation of 3-methylthymine in single-stranded DNA, with concomitant production of succinate, formaldehyde, and carbon dioxide. Consistent with a potential role in nucleic acid demethylation, Fto localizes to the nucleus in transfected cells. Studies of wild-type mice indicate that Fto messenger RNA (mRNA) is most abundant in the brain, particularly in hypothalamic nuclei governing energy balance, and that Fto mRNA levels in the arcuate nucleus are regulated by feeding and fasting. Studies can now be directed toward determining the physiologically relevant FTO substrate and how nucleic acid methylation status is linked to increased fat mass. 相似文献
882.
Culliton BJ 《Science (New York, N.Y.)》1982,218(4577):1098
Representative Albert Gore is reported to be planning to introduce a bill early in the 98th Congress to create a federally mandated committee to oversee genetic engineering research and applications. In the 97th Congress, Gore held hearings on the ethical and legal implications of applications such as gene therapy and the "enhancement" of human characteristics. 相似文献
883.
Haak W Forster P Bramanti B Matsumura S Brandt G Tänzer M Villems R Renfrew C Gronenborn D Alt KW Burger J 《Science (New York, N.Y.)》2005,310(5750):1016-1018
The ancestry of modern Europeans is a subject of debate among geneticists, archaeologists, and anthropologists. A crucial question is the extent to which Europeans are descended from the first European farmers in the Neolithic Age 7500 years ago or from Paleolithic hunter-gatherers who were present in Europe since 40,000 years ago. Here we present an analysis of ancient DNA from early European farmers. We successfully extracted and sequenced intact stretches of maternally inherited mitochondrial DNA (mtDNA) from 24 out of 57 Neolithic skeletons from various locations in Germany, Austria, and Hungary. We found that 25% of the Neolithic farmers had one characteristic mtDNA type and that this type formerly was widespread among Neolithic farmers in Central Europe. Europeans today have a 150-times lower frequency (0.2%) of this mtDNA type, revealing that these first Neolithic farmers did not have a strong genetic influence on modern European female lineages. Our finding lends weight to a proposed Paleolithic ancestry for modern Europeans. 相似文献
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Hydrated minerals occur in accretionary rims around chondrules in CM chondrites. Previous models suggested that these phyllosilicates did not form by gas-solid reactions in the canonical solar nebula. We propose that chondrule-forming shock waves in icy regions of the nebula produced conditions that allowed rapid mineral hydration. The time scales for phyllosilicate formation are similar to the time it takes for a shocked system to cool from the temperature of phyllosilicate stability to that of water ice condensation. This scenario allows for simultaneous formation of chondrules and their fine-grained accretionary rims. 相似文献
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The location of the breakover of the hoof capsule can be positioned through shoe placement, shoe shape, or trimming on barefoot horses. Placing the breakover in relation to the tip of PIII is a more dependable location than placing breakover guided only by visual evaluation of the hoof capsule. The hoof-pastern axis and the position of the navicular bone will be affected by the distance from the apex of the frog to breakover. The resulting decrease in strain of the deep digital flexor tendon while standing and during movement will decrease inflammation and disease in the equine digit. 相似文献
890.
Renzo Torricelli Barbara Tiranti Giorgia Spataro Gildo Castellini Emidio Albertini Mario Falcinelli Valeria Negri 《Genetic Resources and Crop Evolution》2013,60(3):995-1006
The “Sedano Nero di Trevi” (Black Celery from Trevi) is a landrace grown in Umbria (Italy) at risk of extinction. A morpho-physiological and molecular characterisation of the landrace and a detailed investigation of its cultural and cultivation context were carried out with the aim of facilitating a request for a quality mark, implement in situ (on farm) conservation schemes that are being developed in Italy and register the landrace in the European common catalogue of ‘conservation varieties’. These actions can help the landrace survive. Six farmer populations of the landrace and four élite varieties were characterised for thirteen morpho-physiological traits and nine AFLP primer combinations. The “Sedano Nero” farmer populations were better performers than élite varieties for important agronomic traits, such as yield, under the local agronomic conditions. Both morpho-physiological traits and molecular markers clearly distinguished the landrace from the élite cultivars. In addition, a structure was detected in the landrace with farmer populations being characterised by specific alleles. These results are discussed in connection with the local seed system and possible in situ conservation strategies for landraces. 相似文献