Comment on "Long-lived Drosophila with overexpressed dFOXO in adult fat body"     

Tatar M 《Science (New York, N.Y.)》2005,307(5710):675; author reply 675

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Mediation of poly(ADP-ribose) polymerase-1-dependent cell death by apoptosis-inducing factor     

Yu SW  Wang H  Poitras MF  Coombs C  Bowers WJ  Federoff HJ  Poirier GG  Dawson TM  Dawson VL 《Science (New York, N.Y.)》2002,297(5579):259-263

Poly(ADP-ribose) polymerase-1 (PARP-1) protects the genome by functioning in the DNA damage surveillance network. PARP-1 is also a mediator of cell death after ischemia-reperfusion injury, glutamate excitotoxicity, and various inflammatory processes. We show that PARP-1 activation is required for translocation of apoptosis-inducing factor (AIF) from the mitochondria to the nucleus and that AIF is necessary for PARP-1-dependent cell death. N-methyl-N'-nitro-N-nitrosoguanidine, H2O2, and N-methyl-d-aspartate induce AIF translocation and cell death, which is prevented by PARP inhibitors or genetic knockout of PARP-1, but is caspase independent. Microinjection of an antibody to AIF protects against PARP-1-dependent cytotoxicity. These data support a model in which PARP-1 activation signals AIF release from mitochondria, resulting in a caspase-independent pathway of programmed cell death.  相似文献   

The structure of ferrihydrite, a nanocrystalline material   总被引：2，自引：0，他引：2  

Michel FM  Ehm L  Antao SM  Lee PL  Chupas PJ  Liu G  Strongin DR  Schoonen MA  Phillips BL  Parise JB 《Science (New York, N.Y.)》2007,316(5832):1726-1729

Despite the ubiquity of ferrihydrite in natural sediments and its importance as an industrial sorbent, the nanocrystallinity of this iron oxyhydroxide has hampered accurate structure determination by traditional methods that rely on long-range order. We uncovered the atomic arrangement by real-space modeling of the pair distribution function (PDF) derived from direct Fourier transformation of the total x-ray scattering. The PDF for ferrihydrite synthesized with the use of different routes is consistent with a single phase (hexagonal space group P6(3)mc; a = approximately 5.95 angstroms, c = approximately 9.06 angstroms). In its ideal form, this structure contains 20% tetrahedrally and 80% octahedrally coordinated iron and has a basic structural motif closely related to the Baker-Figgis delta-Keggin cluster. Real-space fitting indicates structural relaxation with decreasing particle size and also suggests that second-order effects such as internal strain, stacking faults, and particle shape contribute to the PDFs.  相似文献   

Hepatic glucose sensing via the CREB coactivator CRTC2   总被引：1，自引：0，他引：1  

Dentin R  Hedrick S  Xie J  Yates J  Montminy M 《Science (New York, N.Y.)》2008,319(5868):1402-1405

Chronic hyperglycemia contributes to the development of diabetes-associated complications. Increases in the concentration of circulating glucose activate the hexosamine biosynthetic pathway (HBP) and promote the O-glycosylation of proteins by O-glycosyl transferase (OGT). We show that OGT triggered hepatic gluconeogenesis through the O-glycosylation of the transducer of regulated cyclic adenosine monophosphate response element-binding protein (CREB) 2 (TORC2 or CRTC2). CRTC2 was O-glycosylated at sites that normally sequester CRTC2 in the cytoplasm through a phosphorylation-dependent mechanism. Decreasing amounts of O-glycosylated CRTC2 by expression of the deglycosylating enzyme O-GlcNAcase blocked effects of glucose on gluconeogenesis, demonstrating the importance of the HBP in the development of glucose intolerance.  相似文献   

A haptoglobin-hemoglobin receptor conveys innate immunity to Trypanosoma brucei in humans     

Vanhollebeke B  De Muylder G  Nielsen MJ  Pays A  Tebabi P  Dieu M  Raes M  Moestrup SK  Pays E 《Science (New York, N.Y.)》2008,320(5876):677-681

The protozoan parasite Trypanosoma brucei is lysed by apolipoprotein L-I, a component of human high-density lipoprotein (HDL) particles that are also characterized by the presence of haptoglobin-related protein. We report that this process is mediated by a parasite glycoprotein receptor, which binds the haptoglobin-hemoglobin complex with high affinity for the uptake and incorporation of heme into intracellular hemoproteins. In mice, this receptor was required for optimal parasite growth and the resistance of parasites to the oxidative burst by host macrophages. In humans, the trypanosome receptor also recognized the complex between hemoglobin and haptoglobin-related protein, which explains its ability to capture trypanolytic HDLs. Thus, in humans the presence of haptoglobin-related protein has diverted the function of the trypanosome haptoglobin-hemoglobin receptor to elicit innate host immunity against the parasite.  相似文献   

Crystal structure of the eukaryotic 40S ribosomal subunit in complex with initiation factor 1     

Rabl J  Leibundgut M  Ataide SF  Haag A  Ban N 《Science (New York, N.Y.)》2011,331(6018):730-736

Eukaryotic ribosomes are substantially larger and more complex than their bacterial counterparts. Although their core function is conserved, bacterial and eukaryotic protein synthesis differ considerably at the level of initiation. The eukaryotic small ribosomal subunit (40S) plays a central role in this process; it binds initiation factors that facilitate scanning of messenger RNAs and initiation of protein synthesis. We have determined the crystal structure of the Tetrahymena thermophila 40S ribosomal subunit in complex with eukaryotic initiation factor 1 (eIF1) at a resolution of 3.9 angstroms. The structure reveals the fold of the entire 18S ribosomal RNA and of all ribosomal proteins of the 40S subunit, and defines the interactions with eIF1. It provides insights into the eukaryotic-specific aspects of protein synthesis, including the function of eIF1 as well as signaling and regulation mediated by the ribosomal proteins RACK1 and rpS6e.  相似文献   

Natural history. Beyond the chimpanzee genome: the threat of extinction     

Hauser MD 《Science (New York, N.Y.)》2005,309(5740):1498-1499

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Infectious behavior in a parasitoid     

Varaldi J  Fouillet P  Ravallec M  López-Ferber M  Boulétreau M  Fleury F 《Science (New York, N.Y.)》2003,302(5652):1930

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Holocene deglaciation of Marie Byrd Land,West Antarctica     

Stone JO  Balco GA  Sugden DE  Caffee MW  Sass LC  Cowdery SG  Siddoway C 《Science (New York, N.Y.)》2003,299(5603):99-102

Surface exposure ages of glacial deposits in the Ford Ranges of western Marie Byrd Land indicate continuous thinning of the West Antarctic Ice Sheet by more than 700 meters near the coast throughout the past 10,000 years. Deglaciation lagged the disappearance of ice sheets in the Northern Hemisphere by thousands of years and may still be under way. These results provide further evidence that parts of the West Antarctic Ice Sheet are on a long-term trajectory of decline. West Antarctic melting contributed water to the oceans in the late Holocene and may continue to do so in the future.  相似文献   

Orangutan cultures and the evolution of material culture     

van Schaik CP  Ancrenaz M  Borgen G  Galdikas B  Knott CD  Singleton I  Suzuki A  Utami SS  Merrill M 《Science (New York, N.Y.)》2003,299(5603):102-105

Geographic variation in some aspects of chimpanzee behavior has been interpreted as evidence for culture. Here we document similar geographic variation in orangutan behaviors. Moreover, as expected under a cultural interpretation, we find a correlation between geographic distance and cultural difference, a correlation between the abundance of opportunities for social learning and the size of the local cultural repertoire, and no effect of habitat on the content of culture. Hence, great-ape cultures exist, and may have done so for at least 14 million years.  相似文献