排序方式: 共有59条查询结果,搜索用时 15 毫秒
51.
52.
A satellite view of aerosols in the climate system 总被引:55,自引:0,他引:55
Anthropogenic aerosols are intricately linked to the climate system and to the hydrologic cycle. The net effect of aerosols is to cool the climate system by reflecting sunlight. Depending on their composition, aerosols can also absorb sunlight in the atmosphere, further cooling the surface but warming the atmosphere in the process. These effects of aerosols on the temperature profile, along with the role of aerosols as cloud condensation nuclei, impact the hydrologic cycle, through changes in cloud cover, cloud properties and precipitation. Unravelling these feedbacks is particularly difficult because aerosols take a multitude of shapes and forms, ranging from desert dust to urban pollution, and because aerosol concentrations vary strongly over time and space. To accurately study aerosol distribution and composition therefore requires continuous observations from satellites, networks of ground-based instruments and dedicated field experiments. Increases in aerosol concentration and changes in their composition, driven by industrialization and an expanding population, may adversely affect the Earth's climate and water supply. 相似文献
53.
54.
The unanticipated involvement of several intraflagellar transport proteins in the mammalian Hedgehog (Hh) pathway has hinted at a functional connection between cilia and Hh signal transduction. Here we show that mammalian Smoothened (Smo), a seven-transmembrane protein essential for Hh signalling, is expressed on the primary cilium. This ciliary expression is regulated by Hh pathway activity; Sonic hedgehog or activating mutations in Smo promote ciliary localization, whereas the Smo antagonist cyclopamine inhibits ciliary localization. The translocation of Smo to primary cilia depends upon a conserved hydrophobic and basic residue sequence homologous to a domain previously shown to be required for the ciliary localization of seven-transmembrane proteins in Caenorhabditis elegans. Mutation of this domain not only prevents ciliary localization but also eliminates Smo activity both in cultured cells and in zebrafish embryos. Thus, Hh-dependent translocation to cilia is essential for Smo activity, suggesting that Smo acts at the primary cilium. 相似文献
55.
56.
57.
58.
Crow YJ Leitch A Hayward BE Garner A Parmar R Griffith E Ali M Semple C Aicardi J Babul-Hirji R Baumann C Baxter P Bertini E Chandler KE Chitayat D Cau D Déry C Fazzi E Goizet C King MD Klepper J Lacombe D Lanzi G Lyall H Martínez-Frías ML Mathieu M McKeown C Monier A Oade Y Quarrell OW Rittey CD Rogers RC Sanchis A Stephenson JB Tacke U Till M Tolmie JL Tomlin P Voit T Weschke B Woods CG Lebon P Bonthron DT Ponting CP Jackson AP 《Nature genetics》2006,38(8):910-916
Aicardi-Goutières syndrome (AGS) is an autosomal recessive neurological disorder, the clinical and immunological features of which parallel those of congenital viral infection. Here we define the composition of the human ribonuclease H2 enzyme complex and show that AGS can result from mutations in the genes encoding any one of its three subunits. Our findings demonstrate a role for ribonuclease H in human neurological disease and suggest an unanticipated relationship between ribonuclease H2 and the antiviral immune response that warrants further investigation. 相似文献
59.
APP locus duplication causes autosomal dominant early-onset Alzheimer disease with cerebral amyloid angiopathy 总被引:24,自引:0,他引:24
Rovelet-Lecrux A Hannequin D Raux G Le Meur N Laquerrière A Vital A Dumanchin C Feuillette S Brice A Vercelletto M Dubas F Frebourg T Campion D 《Nature genetics》2006,38(1):24-26
We report duplication of the APP locus on chromosome 21 in five families with autosomal dominant early-onset Alzheimer disease (ADEOAD) and cerebral amyloid angiopathy (CAA). Among these families, the duplicated segments had a minimal size ranging from 0.58 to 6.37 Mb. Brains from individuals with APP duplication showed abundant parenchymal and vascular deposits of amyloid-beta peptides. Duplication of the APP locus, resulting in accumulation of amyloid-beta peptides, causes ADEOAD with CAA. 相似文献