排序方式: 共有26条查询结果,搜索用时 15 毫秒
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Stahl EA Wegmann D Trynka G Gutierrez-Achury J Do R Voight BF Kraft P Chen R Kallberg HJ Kurreeman FA;Diabetes Genetics Replication Meta-analysis Consortium;Myocardial Infarction Genetics Consortium Kathiresan S Wijmenga C Gregersen PK Alfredsson L Siminovitch KA Worthington J de Bakker PI Raychaudhuri S Plenge RM 《Nature genetics》2012,44(5):483-489
The genetic architectures of common, complex diseases are largely uncharacterized. We modeled the genetic architecture underlying genome-wide association study (GWAS) data for rheumatoid arthritis and developed a new method using polygenic risk-score analyses to infer the total liability-scale variance explained by associated GWAS SNPs. Using this method, we estimated that, together, thousands of SNPs from rheumatoid arthritis GWAS explain an additional 20% of disease risk (excluding known associated loci). We further tested this method on datasets for three additional diseases and obtained comparable estimates for celiac disease (43% excluding the major histocompatibility complex), myocardial infarction and coronary artery disease (48%) and type 2 diabetes (49%). Our results are consistent with simulated genetic models in which hundreds of associated loci harbor common causal variants and a smaller number of loci harbor multiple rare causal variants. These analyses suggest that GWAS will continue to be highly productive for the discovery of additional susceptibility loci for common diseases. 相似文献
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小鼠腔前卵泡卵母细胞的体外培养、体外成熟和体外受精研究 总被引:20,自引:0,他引:20
小鼠腔前卵泡在体外生长过程中,于培养液中添加血清,以及FSH和胰岛素均对小鼠腔前卵泡的体外生长、体外成熟、体外受精起促进作用,其中以胰岛素的效果最为显著,腔前卵泡的体外成熟率和体外受精率可达69.4%和80.6%,但是体外受精后的体外发育率低于添加FSH的试验组,表明FSH有益于卵母细胞生长过程中细胞质的成熟。单层培养的卵巢颗粒细胞对腔前卵泡的体外生长也具有促进作用。将体外受精后发育至2—细胞的胚胎移植入受体鼠,胚胎可以正常着床发育。同时,卵母细胞的核仁和线粒体在培养过程中也发生相应的变化。 相似文献
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The magnetic field in the central few hundred parsecs of the Milky Way has a dipolar geometry and is substantially stronger than elsewhere in the Galaxy, with estimates ranging up to a milligauss (refs 1-6). Characterization of the magnetic field at the Galactic Centre is important because it can affect the orbits of molecular clouds by exerting a drag on them, inhibit star formation, and could guide a wind of hot gas or cosmic rays away from the central region. Here we report observations of an infrared nebula having the morphology of an intertwined double helix about 100 parsecs from the Galaxy's dynamical centre, with its axis oriented perpendicular to the Galactic plane. The observed segment is about 25 parsecs in length, and contains about 1.25 full turns of each of the two continuous, helically wound strands. We interpret this feature as a torsional Alfvén wave propagating vertically away from the Galactic disk, driven by rotation of the magnetized circumnuclear gas disk. The direct connection between the circumnuclear disk and the double helix is ambiguous, but the images show a possible meandering channel that warrants further investigation. 相似文献
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Hyun Woo Choi Jong Soo Kim Hyo Jin Jang Sol Choi Jae-Hwan Kim Hans R. Sch?ler Jeong Tae Do 《Cellular and molecular life sciences : CMLS》2012,69(23):4067-4077
The restricted gene expression pattern of a differentiated cell can be reversed by fusion of the somatic cell with a more developmentally potent cell type, such as an embryonic stem (ES) cell. During this reprogramming process, somatic cells obtain most of the characteristics of pluripotent cells. Reactivation of an inactive X chromosome (Xi) is an important epigenetic marker confirming the pluripotent reprogramming of somatic cells. Female somatic cells contain one active X chromosome (Xa) and one Xi, and following the fusion of these cells with male ES cells, the Xi becomes activated, resulting in XaXaXaY fusion hybrid cells. To monitor Xi reactivation, transgenic female neural stem cells (fNSCs) carrying a green fluorescent protein (GFP) reporter gene expressed on the Xa (X-GFP), but not on the Xi, were used for reprogramming. XaXiGFP NSCs, whose GFP reporter was silenced, were fused with HM1 ES cells (XY) to induce pluripotent reprogramming. The XiGFP of NSCs were found to be activated on day 4 post-fusion, indicating reactivation of the Xi. Hybrid cells showed pluripotent cell-specific characteristics cells including inactivation of the NSC marker Nestin, DNA demethylation of Oct4, DNA methylation of Nestin, and reactivation of the Xi. Following differentiation of the (GFP-positive) hybrid cells through embryoid body formation, the proportion of GFP-negative cells was found to be approximately 26?%, indicating that there was random inactivation of one of the three Xas. Here, we showed that the Xi of somatic cells is reprogrammed to the Xa state and that cellular differentiation occurs randomly, i.e., regardless of the Xa or Xi state, indicating that the memory of the Xi of somatic cells has been erased and reset to the ground state (i.e., inner cell mass-like state), indicating that random X-chromosome inactivation occurs upon differentiation. 相似文献