A seven-transmembrane RGS protein that modulates plant cell proliferation     

Chen JG  Willard FS  Huang J  Liang J  Chasse SA  Jones AM  Siderovski DP 《Science (New York, N.Y.)》2003,301(5640):1728-1731

G protein-coupled receptors (GPCRs) at the cell surface activate heterotrimeric G proteins by inducing the G protein alpha (Galpha) subunit to exchange guanosine diphosphate for guanosine triphosphate. Regulators of G protein signaling (RGS) proteins accelerate the deactivation of Galpha subunits to reduce GPCR signaling. Here we identified an RGS protein (AtRGS1) in Arabidopsis that has a predicted structure similar to a GPCR as well as an RGS box with GTPase accelerating activity. Expression of AtRGS1 complemented the pheromone supersensitivity phenotype of a yeast RGS mutant, sst2Delta. Loss of AtRGS1 increased the activity of the Arabidopsis Galpha subunit, resulting in increased cell elongation in hypocotyls in darkness and increased cell production in roots grown in light. These findings suggest that AtRGS1 is a critical modulator of plant cell proliferation.  相似文献   

Growth of epitaxial nanowires at the junctions of nanowalls     

Ng HT  Li J  Smith MK  Nguyen P  Cassell A  Han J  Meyyappan M 《Science (New York, N.Y.)》2003,300(5623):1249

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A survey method for characterizing daily life experience: the day reconstruction method   总被引：3，自引：0，他引：3  

Kahneman D  Krueger AB  Schkade DA  Schwarz N  Stone AA 《Science (New York, N.Y.)》2004,306(5702):1776-1780

The Day Reconstruction Method (DRM) assesses how people spend their time and how they experience the various activities and settings of their lives, combining features of time-budget measurement and experience sampling. Participants systematically reconstruct their activities and experiences of the preceding day with procedures designed to reduce recall biases. The DRM's utility is shown by documenting close correspondences between the DRM reports of 909 employed women and established results from experience sampling. An analysis of the hedonic treadmill shows the DRM's potential for well-being research.  相似文献   

Metapopulation persistence with age-dependent disturbance or succession     

Hastings A 《Science (New York, N.Y.)》2003,301(5639):1525-1526

Simple metapopulation models with random disturbances are used in species conservation or management, relying on the condition for persistence that the per-patch colonization rate be greater than the per-patch extinction rate. For a general model incorporating the role of succession or patch age-dependent extinction, I show that persistence requires the per-patch colonization rate to be greater than the inverse of mean patch age, where age is the time since the patch became available for colonization. Because mean patch age can be arbitrarily large relative to the extinction rate, currently persisting metapopulations may be persisting despite small colonization rates, and management approaches that do not consider the role of mean patch age may unnecessarily doom populations to extinction.  相似文献   

Widespread RNA and DNA sequence differences in the human transcriptome     

Li M  Wang IX  Li Y  Bruzel A  Richards AL  Toung JM  Cheung VG 《Science (New York, N.Y.)》2011,333(6038):53-58

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Viewing NASA's Mars budget with resignation     

Stern A 《Science (New York, N.Y.)》2008,322(5902):672-673

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Dissecting apicoplast targeting in the malaria parasite Plasmodium falciparum     

Foth BJ  Ralph SA  Tonkin CJ  Struck NS  Fraunholz M  Roos DS  Cowman AF  McFadden GI 《Science (New York, N.Y.)》2003,299(5607):705-708

Transit peptides mediate protein targeting into plastids and are only poorly understood. We extracted amino acid features from transit peptides that target proteins to the relict plastid (apicoplast) of malaria parasites. Based on these amino acid characteristics, we identified 466 putative apicoplast proteins in the Plasmodium falciparum genome. Altering the specific charge characteristics in a model transit peptide by site-directed mutagenesis severely disrupted organellar targeting in vivo. Similarly, putative Hsp70 (DnaK) binding sites present in the transit peptide proved to be important for correct targeting.  相似文献   

The growth factor progranulin binds to TNF receptors and is therapeutic against inflammatory arthritis in mice   总被引：1，自引：0，他引：1  

Tang W  Lu Y  Tian QY  Zhang Y  Guo FJ  Liu GY  Syed NM  Lai Y  Lin EA  Kong L  Su J  Yin F  Ding AH  Zanin-Zhorov A  Dustin ML  Tao J  Craft J  Yin Z  Feng JQ  Abramson SB  Yu XP  Liu CJ 《Science (New York, N.Y.)》2011,332(6028):478-484

The growth factor progranulin (PGRN) has been implicated in embryonic development, tissue repair, tumorigenesis, and inflammation, but its receptors remain unidentified. We report that PGRN bound directly to tumor necrosis factor receptors (TNFRs) and disturbed the TNFα-TNFR interaction. PGRN-deficient mice were susceptible to collagen-induced arthritis, and administration of PGRN reversed inflammatory arthritis. Atsttrin, an engineered protein composed of three PGRN fragments, exhibited selective TNFR binding. PGRN and Atsttrin prevented inflammation in multiple arthritis mouse models and inhibited TNFα-activated intracellular signaling. Collectively, these findings demonstrate that PGRN is a ligand of TNFR, an antagonist of TNFα signaling, and plays a critical role in the pathogenesis of inflammatory arthritis in mice. They also suggest new potential therapeutic interventions for various TNFα-mediated pathologies and conditions, including rheumatoid arthritis.  相似文献   

Early allelic selection in maize as revealed by ancient DNA     

Jaenicke-Després V  Buckler ES  Smith BD  Gilbert MT  Cooper A  Doebley J  Pääbo S 《Science (New York, N.Y.)》2003,302(5648):1206-1208

Maize was domesticated from teosinte, a wild grass, by approximately 6300 years ago in Mexico. After initial domestication, early farmers continued to select for advantageous morphological and biochemical traits in this important crop. However, the timing and sequence of character selection are, thus far, known only for morphological features discernible in corn cobs. We have analyzed three genes involved in the control of plant architecture, storage protein synthesis, and starch production from archaeological maize samples from Mexico and the southwestern United States. The results reveal that the alleles typical of contemporary maize were present in Mexican maize by 4400 years ago. However, as recently as 2000 years ago, allelic selection at one of the genes may not yet have been complete.  相似文献   

Anti-inflammatory activity of human IgG4 antibodies by dynamic Fab arm exchange     

van der Neut Kolfschoten M  Schuurman J  Losen M  Bleeker WK  Martínez-Martínez P  Vermeulen E  den Bleker TH  Wiegman L  Vink T  Aarden LA  De Baets MH  van de Winkel JG  Aalberse RC  Parren PW 《Science (New York, N.Y.)》2007,317(5844):1554-1557

Antibodies play a central role in immunity by forming an interface with the innate immune system and, typically, mediate proinflammatory activity. We describe a novel posttranslational modification that leads to anti-inflammatory activity of antibodies of immunoglobulin G, isotype 4 (IgG4). IgG4 antibodies are dynamic molecules that exchange Fab arms by swapping a heavy chain and attached light chain (half-molecule) with a heavy-light chain pair from another molecule, which results in bispecific antibodies. Mutagenesis studies revealed that the third constant domain is critical for this activity. The impact of IgG4 Fab arm exchange was confirmed in vivo in a rhesus monkey model with experimental autoimmune myasthenia gravis. IgG4 Fab arm exchange is suggested to be an important biological mechanism that provides the basis for the anti-inflammatory activity attributed to IgG4 antibodies.  相似文献