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排序方式: 共有163条查询结果,搜索用时 15 毫秒
41.
Dorota Smolarek Claude Hattab Gholamreza Hassanzadeh-Ghassabeh Sylvie Cochet Carlos Guti��rrez Alexandre G. de Brevern Rachanee Udomsangpetch Julien Picot Magdalena Grodecka Kazimiera Wasniowska Serge Muyldermans Yves Colin Caroline Le Van Kim Marcin Czerwinski Olivier Bertrand 《Cellular and molecular life sciences : CMLS》2010,67(19):3371-3387
Fy blood group antigens are carried by the Duffy antigen receptor for chemokines (DARC), a red cells receptor for Plasmodium vivax broadly implicated in human health and diseases. Recombinant VHHs, or nanobodies, the smallest intact antigen binding fragment derivative from the heavy chain-only antibodies present in camelids, were prepared from a dromedary immunized against DARC N-terminal extracellular domain and selected for DARC binding. A described VHH, CA52, does recognize native DARC on cells. It inhibits P. vivax invasion of erythrocytes and displaces interleukin-8 bound to DARC. The targeted epitope overlaps the well-defined DARC Fy6 epitope. K D of CA52?CDARC equilibrium is sub-nanomolar, hence ideal to develop diagnostic or therapeutic compounds. Immunocapture by immobilized CA52 yielded highly purified DARC from engineered K562 cells. This first report on a VHH with specificity for a red blood cell protein exemplifies VHHs?? potentialities to target, to purify, and to modulate the function of cellular markers. 相似文献
42.
In May 1974 four male spotted bats were netted near St. George, Utah. Contrary to published speculation on Euderma, indications are that the spotted bat in southwest Utah (1) is not a late flyer, (2) does not feed solely on moths, (3) may drop to the ground on occasion to forage, (4) is not a rapid flyer, and (5) appears to utilize crevices as roosting sites. 相似文献
43.
44.
Aury JM Jaillon O Duret L Noel B Jubin C Porcel BM Ségurens B Daubin V Anthouard V Aiach N Arnaiz O Billaut A Beisson J Blanc I Bouhouche K Câmara F Duharcourt S Guigo R Gogendeau D Katinka M Keller AM Kissmehl R Klotz C Koll F Le Mouël A Lepère G Malinsky S Nowacki M Nowak JK Plattner H Poulain J Ruiz F Serrano V Zagulski M Dessen P Bétermier M Weissenbach J Scarpelli C Schächter V Sperling L Meyer E Cohen J Wincker P 《Nature》2006,444(7116):171-178
The duplication of entire genomes has long been recognized as having great potential for evolutionary novelties, but the mechanisms underlying their resolution through gene loss are poorly understood. Here we show that in the unicellular eukaryote Paramecium tetraurelia, a ciliate, most of the nearly 40,000 genes arose through at least three successive whole-genome duplications. Phylogenetic analysis indicates that the most recent duplication coincides with an explosion of speciation events that gave rise to the P. aurelia complex of 15 sibling species. We observed that gene loss occurs over a long timescale, not as an initial massive event. Genes from the same metabolic pathway or protein complex have common patterns of gene loss, and highly expressed genes are over-retained after all duplications. The conclusion of this analysis is that many genes are maintained after whole-genome duplication not because of functional innovation but because of gene dosage constraints. 相似文献
45.
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47.
Eight glacial cycles from an Antarctic ice core 总被引:9,自引:0,他引:9
Augustin L Barbante C Barnes PR Barnola JM Bigler M Castellano E Cattani O Chappellaz J Dahl-Jensen D Delmonte B Dreyfus G Durand G Falourd S Fischer H Flückiger J Hansson ME Huybrechts P Jugie G Johnsen SJ Jouzel J Kaufmann P Kipfstuhl J Lambert F Lipenkov VY Littot GC Longinelli A Lorrain R Maggi V Masson-Delmotte V Miller H Mulvaney R Oerlemans J Oerter H Orombelli G Parrenin F Peel DA Petit JR Raynaud D Ritz C Ruth U Schwander J Siegenthaler U Souchez R Stauffer B Steffensen JP Stenni B 《Nature》2004,429(6992):623-628
The Antarctic Vostok ice core provided compelling evidence of the nature of climate, and of climate feedbacks, over the past 420,000 years. Marine records suggest that the amplitude of climate variability was smaller before that time, but such records are often poorly resolved. Moreover, it is not possible to infer the abundance of greenhouse gases in the atmosphere from marine records. Here we report the recovery of a deep ice core from Dome C, Antarctica, that provides a climate record for the past 740,000 years. For the four most recent glacial cycles, the data agree well with the record from Vostok. The earlier period, between 740,000 and 430,000 years ago, was characterized by less pronounced warmth in interglacial periods in Antarctica, but a higher proportion of each cycle was spent in the warm mode. The transition from glacial to interglacial conditions about 430,000 years ago (Termination V) resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases, but there are significant differences in the patterns of change. The interglacial stage following Termination V was exceptionally long--28,000 years compared to, for example, the 12,000 years recorded so far in the present interglacial period. Given the similarities between this earlier warm period and today, our results may imply that without human intervention, a climate similar to the present one would extend well into the future. 相似文献
48.
Genome duplication in the teleost fish Tetraodon nigroviridis reveals the early vertebrate proto-karyotype 总被引:2,自引:0,他引:2
Jaillon O Aury JM Brunet F Petit JL Stange-Thomann N Mauceli E Bouneau L Fischer C Ozouf-Costaz C Bernot A Nicaud S Jaffe D Fisher S Lutfalla G Dossat C Segurens B Dasilva C Salanoubat M Levy M Boudet N Castellano S Anthouard V Jubin C Castelli V Katinka M Vacherie B Biémont C Skalli Z Cattolico L Poulain J De Berardinis V Cruaud C Duprat S Brottier P Coutanceau JP Gouzy J Parra G Lardier G Chapple C McKernan KJ McEwan P Bosak S Kellis M Volff JN Guigó R Zody MC Mesirov J Lindblad-Toh K 《Nature》2004,431(7011):946-957
Tetraodon nigroviridis is a freshwater puffer fish with the smallest known vertebrate genome. Here, we report a draft genome sequence with long-range linkage and substantial anchoring to the 21 Tetraodon chromosomes. Genome analysis provides a greatly improved fish gene catalogue, including identifying key genes previously thought to be absent in fish. Comparison with other vertebrates and a urochordate indicates that fish proteins have diverged markedly faster than their mammalian homologues. Comparison with the human genome suggests approximately 900 previously unannotated human genes. Analysis of the Tetraodon and human genomes shows that whole-genome duplication occurred in the teleost fish lineage, subsequent to its divergence from mammals. The analysis also makes it possible to infer the basic structure of the ancestral bony vertebrate genome, which was composed of 12 chromosomes, and to reconstruct much of the evolutionary history of ancient and recent chromosome rearrangements leading to the modern human karyotype. 相似文献
49.
Brigitte Cambon de Lavalette Charles Tijus Christine Leproux Olivier Bauer 《Foundations of Science》2005,10(1):25-45
Taxonomy Based modeling was applied to describe drivers’ mental models of variable message signs (VMS’s) displayed on expressways.
Progress in road telematics has made it possible to introduce variable message signs (VMS’s). Sensors embedded in the carriageway
every 500m record certain variables (speed, flow rate, etc.) that are transformed in real time into “driving times” to a given
destination if road conditions do not change.
VMS systems are auto-regulative Man-Machine (AMMI) systems which incorporate a model of the user: if the traffic flow is too
high, then drivers should choose alternative routes. In so doing, the traffic flow should decrease. The model of the user
is based on suppositions such as: people do not like to waste time, they fully understand the displayed messages, they trust
the displayed values, they know of alternative routes. However, people also have a model of the way the system functions.
And if they do not believe the contents of the message, they will not act as expected.
We collected data through interviews with drivers using the critical incidents technique (Flanagan, 1985). Results show that
the mental models that drivers have of the way the VMS system works are various but not numerous and that most of them differ
from the“ideal expert” mental model. It is clear that users don’t have an adequate model of how the VMS system works and that
VMS planners have a model of user behaviour that does not correspond to the behaviour of the drivers we interviewed. Finally,
Taxonomy Based Modeling is discussed as a tool for mental model remediation. 相似文献
50.
Treiner E Duban L Bahram S Radosavljevic M Wanner V Tilloy F Affaticati P Gilfillan S Lantz O 《Nature》2003,422(6928):164-169
The evolutionary conservation of T lymphocyte subsets bearing T-cell receptors (TCRs) using invariant alpha-chains is indicative of unique functions. CD1d-restricted natural killer T (NK-T) cells that express an invariant Valpha14 TCRalpha chain have been implicated in microbial and tumour responses, as well as in auto-immunity. Here we show that T cells that express the canonical hValpha7.2-Jalpha33 or mValpha19-Jalpha33 TCR rearrangement are preferentially located in the gut lamina propria of humans and mice, respectively, and are therefore genuine mucosal-associated invariant T (MAIT) cells. Selection and/or expansion of this population requires B lymphocytes, as MAIT cells are absent in B-cell-deficient patients and mice. In addition, we show that MAIT cells are selected and/or restricted by MR1, a monomorphic major histocompatibility complex class I-related molecule that is markedly conserved in diverse mammalian species. MAIT cells are not present in germ-free mice, indicating that commensal flora is required for their expansion in the gut lamina propria. This indicates that MAIT cells are probably involved in the host response at the site of pathogen entry, and may regulate intestinal B-cell activity. 相似文献