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排序方式: 共有397条查询结果,搜索用时 250 毫秒
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Kappelman J Rasmussen DT Sanders WJ Feseha M Bown T Copeland P Crabaugh J Fleagle J Glantz M Gordon A Jacobs B Maga M Muldoon K Pan A Pyne L Richmond B Ryan T Seiffert ER Sen S Todd L Wiemann MC Winkler A 《Nature》2003,426(6966):549-552
Afro-Arabian mammalian communities underwent a marked transition near the Oligocene/Miocene boundary at approximately 24 million years (Myr) ago. Although it is well documented that the endemic paenungulate taxa were replaced by migrants from the Northern Hemisphere, the timing and evolutionary dynamics of this transition have long been a mystery because faunas from about 32 to 24 Myr ago are largely unknown. Here we report a late Oligocene fossil assemblage from Ethiopia, which constrains the migration to postdate 27 Myr ago, and yields new insight into the indigenous faunal dynamics that preceded this event. The fauna is composed of large paenungulate herbivores and reveals not only which earlier taxa persisted into the late Oligocene epoch but also demonstrates that one group, the Proboscidea, underwent a marked diversification. When Eurasian immigrants entered Afro-Arabia, a pattern of winners and losers among the endemics emerged: less diverse taxa such as arsinoitheres became extinct, moderately species-rich groups such as hyracoids continued into the Miocene with reduced diversity, whereas the proboscideans successfully carried their adaptive radiation out of Afro-Arabia and across the world. 相似文献
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A proteomic view of the Plasmodium falciparum life cycle 总被引:43,自引:0,他引:43
Florens L Washburn MP Raine JD Anthony RM Grainger M Haynes JD Moch JK Muster N Sacci JB Tabb DL Witney AA Wolters D Wu Y Gardner MJ Holder AA Sinden RE Yates JR Carucci DJ 《Nature》2002,419(6906):520-526
The completion of the Plasmodium falciparum clone 3D7 genome provides a basis on which to conduct comparative proteomics studies of this human pathogen. Here, we applied a high-throughput proteomics approach to identify new potential drug and vaccine targets and to better understand the biology of this complex protozoan parasite. We characterized four stages of the parasite life cycle (sporozoites, merozoites, trophozoites and gametocytes) by multidimensional protein identification technology. Functional profiling of over 2,400 proteins agreed with the physiology of each stage. Unexpectedly, the antigenically variant proteins of var and rif genes, defined as molecules on the surface of infected erythrocytes, were also largely expressed in sporozoites. The detection of chromosomal clusters encoding co-expressed proteins suggested a potential mechanism for controlling gene expression. 相似文献
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