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271.
Vivian JP Duncan RC Berry R O'Connor GM Reid HH Beddoe T Gras S Saunders PM Olshina MA Widjaja JM Harpur CM Lin J Maloveste SM Price DA Lafont BA McVicar DW Clements CS Brooks AG Rossjohn J 《Nature》2011,479(7373):401-405
Members of the killer cell immunoglobulin-like receptor (KIR) family, a large group of polymorphic receptors expressed on natural killer (NK) cells, recognize particular peptide-laden human leukocyte antigen (pHLA) class I molecules and have a pivotal role in innate immune responses. Allelic variation and extensive polymorphism within the three-domain KIR family (KIR3D, domains D0-D1-D2) affects pHLA binding specificity and is linked to the control of viral replication and the treatment outcome of certain haematological malignancies. Here we describe the structure of a human KIR3DL1 receptor bound to HLA-B*5701 complexed with a self-peptide. KIR3DL1 clamped around the carboxy-terminal end of the HLA-B*5701 antigen-binding cleft, resulting in two discontinuous footprints on the pHLA. First, the D0 domain, a distinguishing feature of the KIR3D family, extended towards β2-microglobulin and abutted a region of the HLA molecule with limited polymorphism, thereby acting as an 'innate HLA sensor' domain. Second, whereas the D2-HLA-B*5701 interface exhibited a high degree of complementarity, the D1-pHLA-B*5701 contacts were suboptimal and accommodated a degree of sequence variation both within the peptide and the polymorphic region of the HLA molecule. Although the two-domain KIR (KIR2D) and KIR3DL1 docked similarly onto HLA-C and HLA-B respectively, the corresponding D1-mediated interactions differed markedly, thereby providing insight into the specificity of KIR3DL1 for discrete HLA-A and HLA-B allotypes. Collectively, in association with extensive mutagenesis studies at the KIR3DL1-pHLA-B*5701 interface, we provide a framework for understanding the intricate interplay between peptide variability, KIR3D and HLA polymorphism in determining the specificity requirements of this essential innate interaction that is conserved across primate species. 相似文献
272.
The composition of four radiocarbon-dated, late Pleistocene woodrat middens is reported and analyzed. A date of 11,850 ±550 BP records the first reported macrofossil occurrence in this region of late Pleistocene Pinus monophylla-Juniperus osteosperma woodlands. A 7,800 ±350 BP date documents the most recent J. osteosperma woodlands in this presently coniferless desert area, while a date of 12,100 ±400 BP is the oldest record of juniper woodlands among the four middens. Other juniper and creosote bush desert flora radiocarbon dates along with six pollen profiles were obtained. The research suggests that as recently as 7,800 BP this part of the Mohave Desert was subject to a cooler, moister climate than at present, and that the aboriginal food resources of pinyon seeds and juniper berries were probably available to early prehistoric man in this area. 相似文献
273.
HLA-DQ7 antigen and resistance to variant CJD. 总被引:2,自引:0,他引:2
G S Jackson J A Beck C Navarrete J Brown P M Sutton M Contreras J Collinge 《Nature》2001,414(6861):269-270
274.
低温氧化作用对中国黄土记录剩磁的影响 总被引:4,自引:0,他引:4
系统地研究了黄土/古土壤样品在加热中磁性矿物及其粒径的变化. 实验结果表明, 在100~200℃之间, 因样品中有机质燃烧而产生的还原环境可以提高样品所含磁铁矿的纯度, 并影响样品的岩石磁学性质, 主要表现在: (1) 样品的矫顽力(Hc)和剩磁矫顽力(Hcr)显著减小; (2) 多畴(MD)磁性矿物的含量增多, 而超顺磁(SP)磁性矿物的含量降低; (3) 天然剩磁热退磁有异常显示; (4) 上述变化随成土作用增强而减弱. 进一步的研究表明, 这一还原过程可有效地消除黄土中MD磁铁矿由天然低温氧化作用(LTO)而携带的次生化学剩磁. 相似文献
275.
Scherer SE Muzny DM Buhay CJ Chen R Cree A Ding Y Dugan-Rocha S Gill R Gunaratne P Harris RA Hawes AC Hernandez J Hodgson AV Hume J Jackson A Khan ZM Kovar-Smith C Lewis LR Lozado RJ Metzker ML Milosavljevic A Miner GR Montgomery KT Morgan MB Nazareth LV Scott G Sodergren E Song XZ Steffen D Lovering RC Wheeler DA Worley KC Yuan Y Zhang Z Adams CQ Ansari-Lari MA Ayele M Brown MJ Chen G Chen Z Clerc-Blankenburg KP Davis C Delgado O Dinh HH Draper H Gonzalez-Garay ML Havlak P Jackson LR Jacob LS 《Nature》2006,440(7082):346-351
Human chromosome 12 contains more than 1,400 coding genes and 487 loci that have been directly implicated in human disease. The q arm of chromosome 12 contains one of the largest blocks of linkage disequilibrium found in the human genome. Here we present the finished sequence of human chromosome 12, which has been finished to high quality and spans approximately 132 megabases, representing approximately 4.5% of the human genome. Alignment of the human chromosome 12 sequence across vertebrates reveals the origin of individual segments in chicken, and a unique history of rearrangement through rodent and primate lineages. The rate of base substitutions in recent evolutionary history shows an overall slowing in hominids compared with primates and rodents. 相似文献
276.
Grenyer R Orme CD Jackson SF Thomas GH Davies RG Davies TJ Jones KE Olson VA Ridgely RS Rasmussen PC Ding TS Bennett PM Blackburn TM Gaston KJ Gittleman JL Owens IP 《Nature》2006,444(7115):93-96
Global conservation strategies commonly assume that different taxonomic groups show congruent geographical patterns of diversity, and that the distribution of extinction-prone species in one group can therefore act as a surrogate for vulnerable species in other groups when conservation decisions are being made. The validity of these assumptions remains unclear, however, because previous tests have been limited in both geographical and taxonomic extent. Here we use a database on the global distribution of 19,349 living bird, mammal and amphibian species to show that, although the distribution of overall species richness is very similar among these groups, congruence in the distribution of rare and threatened species is markedly lower. Congruence is especially low among the very rarest species. Cross-taxon congruence is also highly scale dependent, being particularly low at the finer spatial resolutions relevant to real protected areas. 'Hotspots' of rarity and threat are therefore largely non-overlapping across groups, as are areas chosen to maximize species complementarity. Overall, our results indicate that 'silver-bullet' conservation strategies alone will not deliver efficient conservation solutions. Instead, priority areas for biodiversity conservation must be based on high-resolution data from multiple taxa. 相似文献
277.
Summary Some trace metals are required for development and reproduction, and therefore for continuous rearing of the aster leafhopper,Macrosteles fascifrons, on a holidic diet. Requirement for Fe+++ becomes apparent immediately in the 1st generation; for Cu++ and Zn++, in the 3rd. The leafhopper has grown normally and continuously for 3 generations in the absence of manganese.We acknowledge the Minnesota Agricultural Experiment Station and the National Institute of Allergy and Infectious Diseases, USA, for financial supports. 相似文献
278.
279.
Oxygen uptake by illuminated maize leaves 总被引:5,自引:0,他引:5
280.
The effects of endotoxin on mouse liver phospholipid fatty acid composition have been investigated. Administration of endotoxin from Salmonella abortus equi led to a decrease in the polyunsaturated fatty acid content of livers from mice sensitized with Bacille Calmette Guérin (BCG). The content of arachidonic acid fell significantly in both the phosphatidylcholine and phosphatidylinositol fractions whereas in the phosphatidylethanolamine fraction the linoleic acid content was significantly reduced. The polyunsaturated fatty acids were replaced by increased amounts of oleic acid and palmitic acid, leading to a reduction in the polyunsaturated to saturated fatty acid ratio. 相似文献