Phosphorylation of retinoblastoma protein by viral protein with cyclin-dependent kinase function     

Hume AJ  Finkel JS  Kamil JP  Coen DM  Culbertson MR  Kalejta RF 《Science (New York, N.Y.)》2008,320(5877):797-799

As obligate intracellular parasites, viruses expertly modify cellular processes to facilitate their replication and spread, often by encoding genes that mimic the functions of cellular proteins while lacking regulatory features that modify their activity. We show that the human cytomegalovirus UL97 protein has activities similar to cellular cyclin-cyclin-dependent kinase (CDK) complexes. UL97 phosphorylated and inactivated the retinoblastoma tumor suppressor, stimulated cell cycle progression in mammalian cells, and rescued proliferation of Saccharomyces cerevisiae lacking CDK activity. UL97 is not inhibited by the CDK inhibitor p21 and lacks amino acid residues conserved in the CDKs that permit the attenuation of kinase activity. Thus, UL97 represents a functional ortholog of cellular CDKs that is immune from normal CDK control mechanisms.  相似文献   

Nest inheritance is the missing source of direct fitness in a primitively eusocial insect     

Leadbeater E  Carruthers JM  Green JP  Rosser NS  Field J 《Science (New York, N.Y.)》2011,333(6044):874-876

Animals that cooperate with nonrelatives represent a challenge to inclusive fitness theory, unless cooperative behavior is shown to provide direct fitness benefits. Inheritance of breeding resources could provide such benefits, but this route to cooperation has been little investigated in the social insects. We show that nest inheritance can explain the presence of unrelated helpers in a classic social insect model, the primitively eusocial wasp Polistes dominulus. We found that subordinate helpers produced more direct offspring than lone breeders, some while still subordinate but most after inheriting the dominant position. Thus, while indirect fitness obtained through helping relatives has been the dominant paradigm for understanding eusociality in insects, direct fitness is vital to explain cooperation in P. dominulus.  相似文献   

The neural basis of economic decision-making in the Ultimatum Game     

Sanfey AG  Rilling JK  Aronson JA  Nystrom LE  Cohen JD 《Science (New York, N.Y.)》2003,300(5626):1755-1758

The nascent field of neuroeconomics seeks to ground economic decision making in the biological substrate of the brain. We used functional magnetic resonance imaging of Ultimatum Game players to investigate neural substrates of cognitive and emotional processes involved in economic decision-making. In this game, two players split a sum of money;one player proposes a division and the other can accept or reject this. We scanned players as they responded to fair and unfair proposals. Unfair offers elicited activity in brain areas related to both emotion (anterior insula) and cognition (dorsolateral prefrontal cortex). Further, significantly heightened activity in anterior insula for rejected unfair offers suggests an important role for emotions in decision-making.  相似文献   

Phylogenomics: intersection of evolution and genomics     

Eisen JA  Fraser CM 《Science (New York, N.Y.)》2003,300(5626):1706-1707

Much has been gained from genomic and evolutionary studies of species. Combining the perspectives of these different approaches suggests that an integrated phylogenomic approach will be beneficial.  相似文献   

Unmasking the S-phase-promoting potential of cyclin B1     

Moore JD  Kirk JA  Hunt T 《Science (New York, N.Y.)》2003,300(5621):987-990

In higher eukaryotes, the S phase and M phase of the cell cycle are triggered by different cyclin-dependent kinases (CDKs). For example, in frog egg extracts, Cdk1-cyclin B catalyzes entry into mitosis but cannot trigger DNA replication. Two hypotheses can explain this observation: Either Cdk1-cyclin B fails to recognize the key substrates of its S-phase-promoting counterparts, or its activity is somehow regulated to prevent it from activating DNA synthesis. Here, we show that Cdk1-cyclin B1 has cryptic S-phase-promoting abilities that can be unmasked by relocating it from the cytoplasm to the nucleus and moderately stimulating its activity. Subcellular localization of vertebrate CDKs and the control of their activity are thus critical factors for determining their specificity.  相似文献   

20th-century industrial black carbon emissions altered Arctic climate forcing   总被引：1，自引：0，他引：1  

McConnell JR  Edwards R  Kok GL  Flanner MG  Zender CS  Saltzman ES  Banta JR  Pasteris DR  Carter MM  Kahl JD 《Science (New York, N.Y.)》2007,317(5843):1381-1384

Black carbon (BC) from biomass and fossil fuel combustion alters chemical and physical properties of the atmosphere and snow albedo, yet little is known about its emission or deposition histories. Measurements of BC, vanillic acid, and non-sea-salt sulfur in ice cores indicate that sources and concentrations of BC in Greenland precipitation varied greatly since 1788 as a result of boreal forest fires and industrial activities. Beginning about 1850, industrial emissions resulted in a sevenfold increase in ice-core BC concentrations, with most change occurring in winter. BC concentrations after about 1951 were lower but increasing. At its maximum from 1906 to 1910, estimated surface climate forcing in early summer from BC in Arctic snow was about 3 watts per square meter, which is eight times the typical preindustrial forcing value.  相似文献   

Dynamics of mammalian chromosome evolution inferred from multispecies comparative maps     

Murphy WJ  Larkin DM  Everts-van der Wind A  Bourque G  Tesler G  Auvil L  Beever JE  Chowdhary BP  Galibert F  Gatzke L  Hitte C  Meyers SN  Milan D  Ostrander EA  Pape G  Parker HG  Raudsepp T  Rogatcheva MB  Schook LB  Skow LC  Welge M  Womack JE  O'brien SJ  Pevzner PA  Lewin HA 《Science (New York, N.Y.)》2005,309(5734):613-617

The genome organizations of eight phylogenetically distinct species from five mammalian orders were compared in order to address fundamental questions relating to mammalian chromosomal evolution. Rates of chromosome evolution within mammalian orders were found to increase since the Cretaceous-Tertiary boundary. Nearly 20% of chromosome breakpoint regions were reused during mammalian evolution; these reuse sites are also enriched for centromeres. Analysis of gene content in and around evolutionary breakpoint regions revealed increased gene density relative to the genome-wide average. We found that segmental duplications populate the majority of primate-specific breakpoints and often flank inverted chromosome segments, implicating their role in chromosomal rearrangement.  相似文献   

Genetic structure of human populations   总被引：1，自引：0，他引：1  

Rosenberg NA  Pritchard JK  Weber JL  Cann HM  Kidd KK  Zhivotovsky LA  Feldman MW 《Science (New York, N.Y.)》2002,298(5602):2381-2385

We studied human population structure using genotypes at 377 autosomal microsatellite loci in 1056 individuals from 52 populations. Within-population differences among individuals account for 93 to 95% of genetic variation; differences among major groups constitute only 3 to 5%. Nevertheless, without using prior information about the origins of individuals, we identified six main genetic clusters, five of which correspond to major geographic regions, and subclusters that often correspond to individual populations. General agreement of genetic and predefined populations suggests that self-reported ancestry can facilitate assessments of epidemiological risks but does not obviate the need to use genetic information in genetic association studies.  相似文献   

Identification of a DNA nonhomologous end-joining complex in bacteria     

Weller GR  Kysela B  Roy R  Tonkin LM  Scanlan E  Della M  Devine SK  Day JP  Wilkinson A  d'Adda di Fagagna F  Devine KM  Bowater RP  Jeggo PA  Jackson SP  Doherty AJ 《Science (New York, N.Y.)》2002,297(5587):1686-1689

In eukaryotic cells, double-strand breaks (DSBs) in DNA are generally repaired by the pathway of homologous recombination or by DNA nonhomologous end joining (NHEJ). Both pathways have been highly conserved throughout eukaryotic evolution, but no equivalent NHEJ system has been identified in prokaryotes. The NHEJ pathway requires a DNA end-binding component called Ku. We have identified bacterial Ku homologs and show that these proteins retain the biochemical characteristics of the eukaryotic Ku heterodimer. Furthermore, we show that bacterial Ku specifically recruits DNA ligase to DNA ends and stimulates DNA ligation. Loss of these proteins leads to hypersensitivity to ionizing radiation in Bacillus subtilis. These data provide evidence that many bacteria possess a DNA DSB repair apparatus that shares many features with the NHEJ system of eukarya and suggest that this DNA repair pathway arose before the prokaryotic and eukaryotic lineages diverged.  相似文献   

Communication. Social values and the governance of science     

Gaskell G  Einsiedel E  Hallman W  Priest SH  Jackson J  Olsthoorn J 《Science (New York, N.Y.)》2005,310(5756):1908-1909

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