Science

Abnormal brain structure implicated in stimulant drug addiction.

Publication Date: 2012 Feb 3 PMID: 22301321
Authors: Ersche, K. D. - Jones, P. S. - Williams, G. B. - Turton, A. J. - Robbins, T. W. - Bullmore, E. T.
Journal: Science

Addiction to drugs is a major contemporary public health issue, characterized by maladaptive behavior to obtain and consume an increasing amount of drugs at the expense of the individual's health and social and personal life. We discovered abnormalities in fronto-striatal brain systems implicated in self-control in both stimulant-dependent individuals and their biological siblings who have no history of chronic drug abuse; these findings support the idea of an underlying neurocognitive endophenotype for stimulant drug addiction.

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Growth of Western Australian corals in the anthropocene.

Publication Date: 2012 Feb 3 PMID: 22301320
Authors: Cooper, T. F. - O'Leary, R. A. - Lough, J. M.
Journal: Science

Anthropogenic increases of atmospheric carbon dioxide lead to warmer sea surface temperatures and altered ocean chemistry. Experimental evidence suggests that coral calcification decreases as aragonite saturation drops but increases as temperatures rise toward thresholds optimal for coral growth. In situ studies have documented alarming recent declines in calcification rates on several tropical coral reef ecosystems. We show there is no widespread pattern of consistent decline in calcification rates of massive Porites during the 20th century on reefs spanning an 11 degrees latitudinal range in the southeast Indian Ocean off Western Australia. Increasing calcification rates on the high-latitude reefs contrast with the downward trajectory reported for corals on Australia's Great Barrier Reef and provide additional evidence that recent changes in coral calcification are responses to temperature rather than ocean acidification.

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Sequential signaling crosstalk regulates endomesoderm segregation in sea urchin embryos.

Publication Date: 2012 Feb 3 PMID: 22301319
Authors: Sethi, A. J. - Wikramanayake, R. M. - Angerer, R. C. - Range, R. C. - Angerer, L. M.
Journal: Science

The segregation of embryonic endomesoderm into separate endoderm and mesoderm fates is not well understood in deuterostomes. Using sea urchin embryos, we showed that Notch signaling initiates segregation of the endomesoderm precursor field by inhibiting expression of a key endoderm transcription factor in presumptive mesoderm. The regulatory circuit activated by this transcription factor subsequently maintains transcription of a canonical Wnt (cWnt) ligand only in endoderm precursors. This cWnt ligand reinforces the endoderm state, amplifying the distinction between emerging endoderm and mesoderm. Before gastrulation, Notch-dependent nuclear export of an essential beta-catenin transcriptional coactivator from mesoderm renders it refractory to cWnt signals, insulating it against an endoderm fate. Thus, we report that endomesoderm segregation is a progressive process, requiring a succession of regulatory interactions between cWnt and Notch signaling.

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Untangling genomes from metagenomes: revealing an uncultured class of marine Euryarchaeota.

Publication Date: 2012 Feb 3 PMID: 22301318
Authors: Iverson, V. - Morris, R. M. - Frazar, C. D. - Berthiaume, C. T. - Morales, R. L. - Armbrust, E. V.
Journal: Science

Ecosystems are shaped by complex communities of mostly unculturable microbes. Metagenomes provide a fragmented view of such communities, but the ecosystem functions of major groups of organisms remain mysterious. To better characterize members of these communities, we developed methods to reconstruct genomes directly from mate-paired short-read metagenomes. We closed a genome representing the as-yet uncultured marine group II Euryarchaeota, assembled de novo from 1.7% of a metagenome sequenced from surface seawater. The genome describes a motile, photo-heterotrophic cell focused on degradation of protein and lipids and clarifies the origin of proteorhodopsin. It also demonstrates that high-coverage mate-paired sequence can overcome assembly difficulties caused by interstrain variation in complex microbial communities, enabling inference of ecosystem functions for uncultured members.

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Affirmative action policies promote women and do not harm efficiency in the laboratory.

Publication Date: 2012 Feb 3 PMID: 22301317
Authors: Balafoutas, L. - Sutter, M.
Journal: Science

Gender differences in choosing to enter competitions are one source of unequal labor market outcomes concerning wages and promotions. Given that studying the effects of policy interventions to support women is difficult with field data because of measurement problems and potential lack of control, we evaluated, in a set of controlled laboratory experiments, four interventions: quotas, where one of two winners of a competition must be female; two variants of preferential treatment, where a fixed increment is added to women's performance; and repetition of the competition, where a second competition takes place if no woman is among the winners. Compared with no intervention, all interventions encourage women to enter competitions more often, and performance is at least equally good, both during and after the competition.

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Natural variation in a chloride channel subunit confers avermectin resistance in C. elegans.

Publication Date: 2012 Feb 3 PMID: 22301316
Authors: Ghosh, R. - Andersen, E. C. - Shapiro, J. A. - Gerke, J. P. - Kruglyak, L.
Journal: Science

Resistance of nematodes to anthelmintics such as avermectins has emerged as a major global health and agricultural problem, but genes conferring natural resistance to avermectins are unknown. We show that a naturally occurring four-amino-acid deletion in the ligand-binding domain of GLC-1, the alpha-subunit of a glutamate-gated chloride channel, confers resistance to avermectins in the model nematode Caenorhabditis elegans. We also find that the same variant confers resistance to the avermectin-producing bacterium Streptomyces avermitilis. Population-genetic analyses identified two highly divergent haplotypes at the glc-1 locus that have been maintained at intermediate frequencies by long-term balancing selection. These results implicate variation in glutamate-gated chloride channels in avermectin resistance and provide a mechanism by which such resistance can be maintained.

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Iron catalysts for selective anti-Markovnikov alkene hydrosilylation using tertiary silanes.

Publication Date: 2012 Feb 3 PMID: 22301315
Authors: Tondreau, A. M. - Atienza, C. C. - Weller, K. J. - Nye, S. A. - Lewis, K. M. - Delis, J. G. - Chirik, P. J.
Journal: Science

Alkene hydrosilylation, the addition of a silicon hydride (Si-H) across a carbon-carbon double bond, is one of the largest-scale industrial applications of homogeneous catalysis and is used in the commercial production of numerous consumer goods. For decades, precious metals, principally compounds of platinum and rhodium, have been used as catalysts for this reaction class. Despite their widespread application, limitations such as high and volatile catalyst costs and competing side reactions have persisted. Here, we report that well-characterized molecular iron coordination compounds promote the selective anti-Markovnikov addition of sterically hindered, tertiary silanes to alkenes under mild conditions. These Earth-abundant base-metal catalysts, coordinated by optimized bis(imino)pyridine ligands, show promise for industrial application.

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Spin-down of radio millisecond pulsars at genesis.

Publication Date: 2012 Feb 3 PMID: 22301314
Authors: Tauris, T. M.
Journal: Science

Millisecond pulsars are old neutron stars that have been spun up to high rotational frequencies via accretion of mass from a binary companion star. An important issue for understanding the physics of the early spin evolution of millisecond pulsars is the impact of the expanding magnetosphere during the terminal stages of the mass-transfer process. Here, I report binary stellar evolution calculations that show that the braking torque acting on a neutron star, when the companion star decouples from its Roche lobe, is able to dissipate >50% of the rotational energy of the pulsar. This effect may explain the apparent difference in observed spin distributions between x-ray and radio millisecond pulsars and help account for the noticeable age discrepancy with their young white dwarf companions.

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Nanoscopy in a living mouse brain.

Publication Date: 2012 Feb 3 PMID: 22301313
Authors: Berning, S. - Willig, K. I. - Steffens, H. - Dibaj, P. - Hell, S. W.
Journal: Science

We demonstrated superresolution optical microscopy in a living higher animal. Stimulated emission depletion (STED) fluorescence nanoscopy reveals neurons in the cerebral cortex of a mouse with <70-nanometer resolution. Dendritic spines and their subtle changes can be observed at their relevant scales over extended periods of time.

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Physics. Seeing the superfluid transition of a gas.

Publication Date: 2012 Feb 3 PMID: 22301312
Authors: Zwerger, W.
Journal: Science

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Climate change. Marching in near lock-step.

Publication Date: 2012 Feb 3 PMID: 22301311
Authors: Rodbell, D. T.
Journal: Science

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Neuroscience. To stop or not to stop?

Publication Date: 2012 Feb 3 PMID: 22301310
Authors: Volkow, N. D. - Baler, R. D.
Journal: Science

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Evolution. Surviving in a toxic world.

Publication Date: 2012 Feb 3 PMID: 22301309
Authors: Wolstenholme, A. J.
Journal: Science

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Economics. Ready, steady, compete.

Publication Date: 2012 Feb 3 PMID: 22301308
Authors: Villeval, M. C.
Journal: Science

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Scientific publications. Coercive citation in academic publishing.

Publication Date: 2012 Feb 3 PMID: 22301307
Authors: Wilhite, A. W. - Fong, E. A.
Journal: Science

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Proceed with planning despite multiple models.

Publication Date: 2012 Feb 3 PMID: 22301306
Authors: Dickinson, R.
Journal: Science

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Comment on "Abiotic pyrite formation produces a large Fe isotope fractionation".

Publication Date: 2012 Feb 3 PMID: 22301304
Authors: Czaja, A. D. - Johnson, C. M. - Yamaguchi, K. E. - Beard, B. L.
Journal: Science

Guilbaud et al. (Reports, 24 June 2011, p. 1548) suggest that the geologic record of Fe isotope fractionation can be explained by abiological precipitation of pyrite. We argue that a detailed understanding of the depositional setting, mineralogy, and geologic history of Precambrian sedimentary rocks indicates that the Fe isotope record dominantly reflects biological fractionations and Fe redox processes.

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Invasive species unchecked by climate.

Publication Date: 2012 Feb 3 PMID: 22301301
Authors: Hulme, P. E.
Journal: Science

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Investing in Libya's education.

Publication Date: 2012 Feb 3 PMID: 22301300
Authors: Sgaier, S. K.
Journal: Science

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2011 International Science & Engineering Visualization Challenge. Video.

Publication Date: 2012 Feb 3 PMID: 22301299
Authors:
Journal: Science

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2011 International Science & Engineering Visualization Challenge. Interactive games.

Publication Date: 2012 Feb 3 PMID: 22301298
Authors:
Journal: Science

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2011 International Science & Engineering Visualization Challenge. Informational posters & graphics.

Publication Date: 2012 Feb 3 PMID: 22301297
Authors:
Journal: Science

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2011 International Science & Engineering Visualization Challenge. Illustration.

Publication Date: 2012 Feb 3 PMID: 22301296
Authors:
Journal: Science

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2011 International Science & Engineering Visualization Challenge. Photography.

Publication Date: 2012 Feb 3 PMID: 22301295
Authors:
Journal: Science

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2011 International Science & Engineering Visualization Challenge.

Publication Date: 2012 Feb 3 PMID: 22301294
Authors: Norman, C.
Journal: Science

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Oil resources. Technology is turning U.S. oil around but not the world's.

Publication Date: 2012 Feb 3 PMID: 22301293
Authors: Kerr, R. A.
Journal: Science

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Ecology. Rebuilding wetlands by managing the muddy Mississippi.

Publication Date: 2012 Feb 3 PMID: 22301292
Authors: Gramling, C.
Journal: Science

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Genomics. China's sequencing powerhouse comes of age.

Publication Date: 2012 Feb 3 PMID: 22301291
Authors: Normile, D.
Journal: Science

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Astronomy. Celebrated exoplanet vanishes in a cloud of dust--or maybe not.

Publication Date: 2012 Feb 3 PMID: 22301290
Authors: Bhattacharjee, Y.
Journal: Science

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Cell biology. Donation spurs a cell observatory--and bigger plans.

Publication Date: 2012 Feb 3 PMID: 22301289
Authors: Kaiser, J.
Journal: Science

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Avian influenza. The limits of avian flu studies in ferrets.

Publication Date: 2012 Feb 3 PMID: 22301288
Authors: Cohen, J.
Journal: Science

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The global knowledge society.

Publication Date: 2012 Feb 3 PMID: 22301283
Authors: Fedoroff, N. V.
Journal: Science

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Pollinator-Mediated Selection on Flower Color Allele Drives Reinforcement.

Publication Date: 2012 Feb 2 PMID: 22300852
Authors: Hopkins, R. - Rausher, M. D.
Journal: Science

Reinforcement is the process by which reduced hybrid fitness generates selection favoring the evolution of stronger prezygotic reproductive barriers between emerging species. Using common-garden field experiments, we quantified the strength of reinforcing selection in nature by demonstrating strong selection favoring an allele conferring increased pigment intensity in the plant Phlox drummondii in areas of sympatry with the closely related species P. cuspidata. Incomplete hybrid sterility between the two species generates selection for traits that decrease interspecies hybridization. By contrast, selection on this locus is undetectable in the absence of P. cuspidata. We demonstrate that reinforcing selection is generated by nonrandom pollinator movement, in which pollinators move less frequently between intensely pigmented P. drummondii and P. cuspidata than between lightly pigmented P. drummondii and P. cuspidata.

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Extremely Long-Lived Nuclear Pore Proteins in the Rat Brain.

Publication Date: 2012 Feb 2 PMID: 22300851
Authors: Savas, J. N. - Toyama, B. H. - Xu, T. - Yates, J. R. - Hetzer, M. W.
Journal: Science

To combat the functional decline of the proteome, cells use the process of protein turnover to replace potentially impaired polypeptides with new functional copies. Here, we found that extremely long-lived proteins (ELLPs) did not turn over in post-mitotic cells of the rat central nervous system. These ELLPs were associated with chromatin and the nuclear pore complex, the central transport channels that mediate all molecular trafficking in and out of the nucleus. The longevity of these proteins would be expected to expose them to potentially harmful metabolites, putting them at risk of accumulating damage over extended periods of time. Thus, it is possible that failure to maintain proper levels and functional integrity of ELLPs in nonproliferative cells might contribute to age-related deterioration in cell and tissue function.

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ER Cargo Properties Specify a Requirement for COPII Coat Rigidity Mediated by Sec13p.

Publication Date: 2012 Feb 2 PMID: 22300850
Authors: Copic, A. - Latham, C. F. - Horlbeck, M. A. - D'Arcangelo, J. G. - Miller, E. A.
Journal: Science

Eukaryotic secretory proteins exit the endoplasmic reticulum via transport vesicles generated by the essential COPII coat proteins. The outer coat complex, Sec13-Sec31, forms a scaffold that is thought to enforce curvature. By exploiting yeast bypass-of-sec-thirteen (bst) mutants, where Sec13p is dispensable, we probed the relationship between a compromised COPII coat and the cellular context in which it could still function. Genetic and biochemical analyses suggested that Sec13p was required to generate vesicles from membranes that contained asymmetrically distributed cargoes that were likely to confer opposing curvature. Thus, Sec13p may rigidify the COPII cage and increase its membrane-bending capacity; this function could be bypassed when a bst mutation renders the membrane more deformable.

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Founder Effects Persist Despite Adaptive Differentiation: A Field Experiment with Lizards.

Publication Date: 2012 Feb 2 PMID: 22300849
Authors: Kolbe, J. J. - Leal, M. - Schoener, T. W. - Spiller, D. A. - Losos, J. B.
Journal: Science

The extent to which random processes such as founder events contribute to evolutionary divergence is a long-standing controversy in evolutionary biology. To determine the respective contribution of founder effects and natural selection, we conducted an experiment in which brown anole (Anolis sagrei) lizard populations were established on seven small islands from male-female pairs randomly drawn from the same large-island source. These founding events generated significant among-island genetic and morphological differences that persisted throughout the course of the experiment despite all populations adapting in the predicted direction-shorter hindlimbs-in response to the narrower vegetation on the small islands. Thus, using a replicated experiment in nature, we showed that both founder effects and natural selection jointly determine trait values in these populations.

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Field-Effect Tunneling Transistor Based on Vertical Graphene Heterostructures.

Publication Date: 2012 Feb 2 PMID: 22300848
Authors: Britnell, L. - Gorbachev, R. V. - Jalil, R. - Belle, B. D. - Schedin, F. - Mishchenko, A. - Georgiou, T. - Katsnelson, M. I. - Eaves, L. - Morozov, S. V. - Peres, N. M. - Leist, J. - Geim, A. K. - Novoselov, K. S. - Ponomarenko, L. A.
Journal: Science

An obstacle to the use of graphene as an alternative to silicon electronics has been the absence of an energy gap between its conduction and valence bands, which makes it difficult to achieve low power dissipation in the OFF state. We report a bipolar field-effect transistor that exploits the low density of states in graphene and its one atomic layer thickness. Our prototype devices are graphene heterostructures with atomically thin boron nitride or molybdenum disulfide acting as a vertical transport barrier. They exhibit room temperature switching ratios of approximately 50 and approximately 10,000 respectively. Such devices have potential for high-frequency operation and large-scale integration.

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Adaptations of Avian Flu Virus Are a Cause for Concern.

Publication Date: 2012 Jan 31 PMID: 22294736
Authors: Berns, K. I. - Casadevall, A. - Cohen, M. L. - Ehrlich, S. A. - Enquist, L. W. - Fitch, J. P. - Franz, D. R. - Fraser-Liggett, C. M. - Grant, C. M. - Imperiale, M. J. - Kanabrocki, J. - Keim, P. S. - Lemon, S. M. - Levy, S. B. - Lumpkin, J. R. - Miller, J. F. - Murch, R. - Nance, M. E. - Osterholm, M. T. - Relman, D. A. - Roth, J. A. - Vidaver, A. K.
Journal: Science

Members of the National Science Advisory Board for Biosecurity explain its recommendations on the communication of experimental work on H5N1 influenza.Comment on this article at http://scim.ag/yZJTt9.

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Asymmetric segregation of polarized antigen on B cell division shapes presentation capacity.

Publication Date: 2012 Jan 27 PMID: 22282815
Authors: Thaunat, O. - Granja, A. G. - Barral, P. - Filby, A. - Montaner, B. - Collinson, L. - Martinez-Martin, N. - Harwood, N. E. - Bruckbauer, A. - Batista, F. D.
Journal: Science

During the activation of humoral immune responses, B cells acquire antigen for subsequent presentation to cognate T cells. Here we show that after mouse B cells accumulate antigen, it is maintained in a polarized distribution for extended periods in vivo. Using high-throughput imaging flow cytometry, we observed that this polarization is preserved during B cell division, promoting asymmetric antigen segregation among progeny. Antigen inheritance correlates with the ability of progeny to activate T cells: Daughter cells receiving larger antigen stores exhibit a prolonged capacity to present antigen, which renders them more effective in competing for T cell help. The generation of progeny with differential capacities for antigen presentation may have implications for somatic hypermutation and class switching during affinity maturation and as B cells commit to effector cell fates.

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Facilitated cross-species transmission of prions in extraneural tissue.

Publication Date: 2012 Jan 27 PMID: 22282814
Authors: Beringue, V. - Herzog, L. - Jaumain, E. - Reine, F. - Sibille, P. - Le Dur, A. - Vilotte, J. L. - Laude, H.
Journal: Science

Prions are infectious pathogens essentially composed of PrP(Sc), an abnormally folded form of the host-encoded prion protein PrP(C). Constrained steric interactions between PrP(Sc) and PrP(C) are thought to provide prions with species specificity and to control cross-species transmission into other host populations, including humans. We compared the ability of brain and lymphoid tissues from ovine and human PrP transgenic mice to replicate foreign, inefficiently transmitted prions. Lymphoid tissue was consistently more permissive than the brain to prions such as those causing chronic wasting disease and bovine spongiform encephalopathy. Furthermore, when the transmission barrier was overcome through strain shifting in the brain, a distinct agent propagated in the spleen, which retained the ability to infect the original host. Thus, prion cross-species transmission efficacy can exhibit a marked tissue dependence.

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Depth perception from image defocus in a jumping spider.

Publication Date: 2012 Jan 27 PMID: 22282813
Authors: Nagata, T. - Koyanagi, M. - Tsukamoto, H. - Saeki, S. - Isono, K. - Shichida, Y. - Tokunaga, F. - Kinoshita, M. - Arikawa, K. - Terakita, A.
Journal: Science

The principal eyes of jumping spiders have a unique retina with four tiered photoreceptor layers, on each of which light of different wavelengths is focused by a lens with appreciable chromatic aberration. We found that all photoreceptors in both the deepest and second-deepest layers contain a green-sensitive visual pigment, although green light is only focused on the deepest layer. This mismatch indicates that the second-deepest layer always receives defocused images, which contain depth information of the scene in optical theory. Behavioral experiments revealed that depth perception in the spider was affected by the wavelength of the illuminating light, which affects the amount of defocus in the images resulting from chromatic aberration. Therefore, we propose a depth perception mechanism based on how much the retinal image is defocused.

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Heavy livestock grazing promotes locust outbreaks by lowering plant nitrogen content.

Publication Date: 2012 Jan 27 PMID: 22282812
Authors: Cease, A. J. - Elser, J. J. - Ford, C. F. - Hao, S. - Kang, L. - Harrison, J. F.
Journal: Science

Current paradigms generally assume that increased plant nitrogen (N) should enhance herbivore performance by relieving protein limitation, increasing herbivorous insect populations. We show, in contrast to this scenario, that host plant N enrichment and high-protein artificial diets decreased the size and viability of Oedaleus asiaticus, a dominant locust of north Asian grasslands. This locust preferred plants with low N content and artificial diets with low protein and high carbohydrate content. Plant N content was lowest and locust abundance highest in heavily livestock-grazed fields where soils were N-depleted, likely due to enhanced erosion. These results suggest that heavy livestock grazing and consequent steppe degradation in the Eurasian grassland promote outbreaks of this locust by reducing plant protein content.

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Global correlations in tropical tree species richness and abundance reject neutrality.

Publication Date: 2012 Jan 27 PMID: 22282811
Authors: Ricklefs, R. E. - Renner, S. S.
Journal: Science

Patterns of species richness and relative abundance at some scales cannot be distinguished from predictions of null models, including zero-sum neutral models of population change and random speciation-extinction models of evolutionary diversification. Both models predict that species richness or population abundance produced by independent iterations of the same processes in different regions should be uncorrelated. We find instead that the number of species and individuals in families of trees in forest plots are strongly correlated across Southeast Asia, Africa, and tropical America. These correlations imply that deterministic processes influenced by evolutionarily conservative family-level traits constrain the number of confamilial tree species and individuals that can be supported in regional species pools and local assemblages in humid tropical forests.

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The molecular diversity of adaptive convergence.

Publication Date: 2012 Jan 27 PMID: 22282810
Authors: Tenaillon, O. - Rodriguez-Verdugo, A. - Gaut, R. L. - McDonald, P. - Bennett, A. F. - Long, A. D. - Gaut, B. S.
Journal: Science

To estimate the number and diversity of beneficial mutations, we experimentally evolved 115 populations of Escherichia coli to 42.2 degrees C for 2000 generations and sequenced one genome from each population. We identified 1331 total mutations, affecting more than 600 different sites. Few mutations were shared among replicates, but a strong pattern of convergence emerged at the level of genes, operons, and functional complexes. Our experiment uncovered a set of primary functional targets of high temperature, but we estimate that many other beneficial mutations could contribute to similar adaptive outcomes. We inferred the pervasive presence of epistasis among beneficial mutations, which shaped adaptive trajectories into at least two distinct pathways involving mutations either in the RNA polymerase complex or the termination factor rho.

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A long-lived lunar core dynamo.

Publication Date: 2012 Jan 27 PMID: 22282809
Authors: Shea, E. K. - Weiss, B. P. - Cassata, W. S. - Shuster, D. L. - Tikoo, S. M. - Gattacceca, J. - Grove, T. L. - Fuller, M. D.
Journal: Science

Paleomagnetic measurements indicate that a core dynamo probably existed on the Moon 4.2 billion years ago. However, the subsequent history of the lunar core dynamo is unknown. Here we report paleomagnetic, petrologic, and (40)Ar/(39)Ar thermochronometry measurements on the 3.7-billion-year-old mare basalt sample 10020. This sample contains a high-coercivity magnetization acquired in a stable field of at least ~12 microteslas. These data extend the known lifetime of the lunar dynamo by 500 million years. Such a long-lived lunar dynamo probably required a power source other than thermochemical convection from secular cooling of the lunar interior. The inferred strong intensity of the lunar paleofield presents a challenge to current dynamo theory.

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Reversible reduction of oxygen to peroxide facilitated by molecular recognition.

Publication Date: 2012 Jan 27 PMID: 22282808
Authors: Lopez, N. - Graham, D. J. - McGuire, R. Jr - Alliger, G. E. - Shao-Horn, Y. - Cummins, C. C. - Nocera, D. G.
Journal: Science

Generation of soluble sources of peroxide dianion (O(2)(2-)) is a challenge in dioxygen chemistry. The oxidizing nature of this anion renders its stabilization in organic media difficult. This Report describes the chemically reversible reduction of oxygen (O(2)) to cryptand-encapsulated O(2)(2-). The dianion is stabilized by strong hydrogen bonds to N-H groups from the hexacarboxamide cryptand. Analogous stabilization of peroxide by hydrogen bonding has been invoked recently in crystalline saccharide and protein systems. The present peroxide adducts are stable at room temperature in dimethyl sulfoxide (DMSO) and N,N'-dimethylformamide (DMF). These adducts can be obtained in gram quantities from the cryptand-driven disproportionation reaction of potassium superoxide (KO(2)) at room temperature.

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Ultrafast viscous permeation of organic solvents through diamond-like carbon nanosheets.

Publication Date: 2012 Jan 27 PMID: 22282807
Authors: Karan, S. - Samitsu, S. - Peng, X. - Kurashima, K. - Ichinose, I.
Journal: Science

Chemical, petrochemical, energy, and environment-related industries strongly require high-performance nanofiltration membranes applicable to organic solvents. To achieve high solvent permeability, filtration membranes must be as thin as possible, while retaining mechanical strength and solvent resistance. Here, we report on the preparation of ultrathin free-standing amorphous carbon membranes with Young's moduli of 90 to 170 gigapascals. The membranes can separate organic dyes at a rate three orders of magnitude greater than that of commercially available membranes. Permeation experiments revealed that the hard carbon layer has hydrophobic pores of ~1 nanometer, which allow the ultrafast viscous permeation of organic solvents through the membrane.

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Unimpeded permeation of water through helium-leak-tight graphene-based membranes.

Publication Date: 2012 Jan 27 PMID: 22282806
Authors: Nair, R. R. - Wu, H. A. - Jayaram, P. N. - Grigorieva, I. V. - Geim, A. K.
Journal: Science

Permeation through nanometer pores is important in the design of materials for filtration and separation techniques and because of unusual fundamental behavior arising at the molecular scale. We found that submicrometer-thick membranes made from graphene oxide can be completely impermeable to liquids, vapors, and gases, including helium, but these membranes allow unimpeded permeation of water (H(2)O permeates through the membranes at least 10(10) times faster than He). We attribute these seemingly incompatible observations to a low-friction flow of a monolayer of water through two-dimensional capillaries formed by closely spaced graphene sheets. Diffusion of other molecules is blocked by reversible narrowing of the capillaries in low humidity and/or by their clogging with water.

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Crystal structure of the human K2P TRAAK, a lipid- and mechano-sensitive K+ ion channel.

Publication Date: 2012 Jan 27 PMID: 22282805
Authors: Brohawn, S. G. - del Marmol, J. - MacKinnon, R.
Journal: Science

TRAAK channels, members of the two-pore domain K(+) (potassium ion) channel family K2P, are expressed almost exclusively in the nervous system and control the resting membrane potential. Their gating is sensitive to polyunsaturated fatty acids, mechanical deformation of the membrane, and temperature changes. Physiologically, these channels appear to control the noxious input threshold for temperature and pressure sensitivity in dorsal root ganglia neurons. We present the crystal structure of human TRAAK at a resolution of 3.8 angstroms. The channel comprises two protomers, each containing two distinct pore domains, which create a two-fold symmetric K(+) channel. The extracellular surface features a helical cap, 35 angstroms tall, that creates a bifurcated pore entryway and accounts for the insensitivity of two-pore domain K(+) channels to inhibitory toxins. Two diagonally opposed gate-forming inner helices form membrane-interacting structures that may underlie this channel's sensitivity to chemical and mechanical properties of the cell membrane.

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Crystal structure of the human two-pore domain potassium channel K2P1.

Publication Date: 2012 Jan 27 PMID: 22282804
Authors: Miller, A. N. - Long, S. B.
Journal: Science

Two-pore domain potassium (K(+)) channels (K2P channels) control the negative resting potential of eukaryotic cells and regulate cell excitability by conducting K(+) ions across the plasma membrane. Here, we present the 3.4 angstrom resolution crystal structure of a human K2P channel, K2P1 (TWIK-1). Unlike other K(+) channel structures, K2P1 is dimeric. An extracellular cap domain located above the selectivity filter forms an ion pathway in which K(+) ions flow through side portals. Openings within the transmembrane region expose the pore to the lipid bilayer and are filled with electron density attributable to alkyl chains. An interfacial helix appears structurally poised to affect gating. The structure lays a foundation to further investigate how K2P channels are regulated by diverse stimuli.

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Repeatability and contingency in the evolution of a key innovation in phage lambda.

Publication Date: 2012 Jan 27 PMID: 22282803
Authors: Meyer, J. R. - Dobias, D. T. - Weitz, J. S. - Barrick, J. E. - Quick, R. T. - Lenski, R. E.
Journal: Science

The processes responsible for the evolution of key innovations, whereby lineages acquire qualitatively new functions that expand their ecological opportunities, remain poorly understood. We examined how a virus, bacteriophage lambda, evolved to infect its host, Escherichia coli, through a novel pathway. Natural selection promoted the fixation of mutations in the virus's host-recognition protein, J, that improved fitness on the original receptor, LamB, and set the stage for other mutations that allowed infection through a new receptor, OmpF. These viral mutations arose after the host evolved reduced expression of LamB, whereas certain other host mutations prevented the phage from evolving the new function. This study shows the complex interplay between genomic processes and ecological conditions that favor the emergence of evolutionary innovations.

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The centrosome in cells and organisms.

Publication Date: 2012 Jan 27 PMID: 22282802
Authors: Bornens, M.
Journal: Science

The centrosome acts as the main microtubule-nucleating organelle in animal cells and plays a critical role in mitotic spindle orientation and in genome stability. Yet, despite its central role in cell biology, the centrosome is not present in all multicellular organisms or in all cells of a given organism. The main outcome of centrosome reproduction is the transmission of polarity to daughter cells and, in most animal species, the sperm-donated centrosome defines embryo polarity. Here I will discuss the role of the centrosome in cell polarity, resulting from its ability to position the nucleus at the cell center, and discuss how centrosome innovation might have been critical during metazoan evolution.

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IBI series winner. An inquiry-based curriculum for nonmajors.

Publication Date: 2012 Jan 27 PMID: 22282801
Authors: Jackson, D. P. - Laws, P. W. - Franklin, S. V.
Journal: Science

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Structural biology. The inner workings of a dynamic duo.

Publication Date: 2012 Jan 27 PMID: 22282800
Authors: Poulsen, H. - Nissen, P.
Journal: Science

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Neuroscience. Another remembered present.

Publication Date: 2012 Jan 27 PMID: 22282799
Authors: Meyer, K.
Journal: Science

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Marerials science. Creating new types of carbon-based membranes.

Publication Date: 2012 Jan 27 PMID: 22282798
Authors: Paul, D. R.
Journal: Science

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Cell biology. The risk of prion zoonoses.

Publication Date: 2012 Jan 27 PMID: 22282797
Authors: Collinge, J.
Journal: Science

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Evolution. The role of coevolution.

Publication Date: 2012 Jan 27 PMID: 22282796
Authors: Thompson, J. N.
Journal: Science

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Physiology. A clearer view from fuzzy images.

Publication Date: 2012 Jan 27 PMID: 22282795
Authors: Herberstein, M. E. - Kemp, D. J.
Journal: Science

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Immunology. Antigen feast or famine.

Publication Date: 2012 Jan 27 PMID: 22282794
Authors: Dustin, M. L. - Meyer-Hermann, M.
Journal: Science

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Global food supply. Mixed messages on prices and food security.

Publication Date: 2012 Jan 27 PMID: 22282793
Authors: Swinnen, J. - Squicciarini, P.
Journal: Science

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Portugal's Age of Enlightenment.

Publication Date: 2012 Jan 27 PMID: 22282792
Authors: Santos, N. C.
Journal: Science

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Recognizing existing models.

Publication Date: 2012 Jan 27 PMID: 22282791
Authors: Rosenberg, W. J.
Journal: Science

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Comment on "Dynamics of dpp signaling and proliferation control".

Publication Date: 2012 Jan 27 PMID: 22282789
Authors: Schwank, G. - Yang, S. F. - Restrepo, S. - Basler, K.
Journal: Science

Wartlick et al. (Research Articles, 4 March 2011, p. 1154) reported that growth rates in the Drosophila wing disc correlate with increasing Dpp signaling levels, suggesting that the rate of Dpp increase determines the cell-cycle length. Contradicting their model, we found that cells in which the increase of Dpp signaling levels was genetically abrogated grew at rates comparable to those of wild-type cells.

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Pause on avian flu transmission research.

Publication Date: 2012 Jan 27 PMID: 22282787
Authors: Fouchier, R. A. - Garcia-Sastre, A. - Kawaoka, Y. - Barclay, W. S. - Bouvier, N. M. - Brown, I. H. - Capua, I. - Chen, H. - Compans, R. W. - Couch, R. B. - Cox, N. J. - Doherty, P. C. - Donis, R. O. - Feldmann, H. - Guan, Y. - Katz, J. - Klenk, H. D. - Kobinger, G. - Liu, J. - Liu, X. - Lowen, A. - Mettenleiter, T. C. - Osterhaus, A. D. - Palese, P. - Peiris, J. S. - Perez, D. R. - Richt, J. A. - Schultz-Cherry, S. - Steel, J. - Subbarao, K. - Swayne, D. E. - Takimoto, T. - Tashiro, M. - Taubenberger, J. K. - Thomas, P. G. - Tripp, R. A. - Tumpey, T. M. - Webby, R. J. - Webster, R. G.
Journal: Science

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Behavioral sciences. Modernizing an academic monastery.

Publication Date: 2012 Jan 27 PMID: 22282786
Authors: Miller, G.
Journal: Science

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Geoscience. Ferreting out the hidden cracks in the heart of a continent.

Publication Date: 2012 Jan 27 PMID: 22282785
Authors: Lubick, N.
Journal: Science

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Computer science. What it'll take to go exascale.

Publication Date: 2012 Jan 27 PMID: 22282784
Authors: Service, R. F.
Journal: Science

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Nuclear physics. DOE funding crunch threatens future of only U.S. collider still running.

Publication Date: 2012 Jan 27 PMID: 22282783
Authors: Cho, A.
Journal: Science

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Astronomy. Worldwide telescope aims to look into Milky Way galaxy's black heart.

Publication Date: 2012 Jan 27 PMID: 22282782
Authors: Clery, D.
Journal: Science

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China. An explosive return of the 'great pox'.

Publication Date: 2012 Jan 27 PMID: 22282781
Authors: Hvistendahl, M.
Journal: Science

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H5N1. Ron Fouchier: in the eye of the storm.

Publication Date: 2012 Jan 27 PMID: 22282780
Authors: Fouchier, R.
Journal: Science

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H5N1. Flu controversy spurs research moratorium.

Publication Date: 2012 Jan 27 PMID: 22282779
Authors: Malakoff, D.
Journal: Science

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Teaching real science.

Publication Date: 2012 Jan 27 PMID: 22282774
Authors: Alberts, B.
Journal: Science

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Unraveling the Spin Polarization of the nu = 5/2 Fractional Quantum Hall State.

Publication Date: 2012 Jan 26 PMID: 22282477
Authors: Tiemann, L. - Gamez, G. - Kumada, N. - Muraki, K.
Journal: Science

The fractional quantum Hall (FQH) effect at filling factor nu = 5/2 has recently come under close scrutiny, as its ground state may possess quasiparticle excitations obeying non-Abelian statistics, a property sought for topologically protected quantum operations. However, its microscopic origin remains unknown, and candidate model wave functions include those with undesirable abelian statistics. We report direct measurements of the electron spin polarization of the nu = 5/2 FQH state using resistively detected nuclear magnetic resonance. We find the system to be fully polarized, which unambiguously rules out the most likely Abelian contender and lends strong support for the nu = 5/2 state being non-Abelian. Our measurements reveal an intrinsically different nature of interaction in the first excited Landau level underlying the physics at nu = 5/2.

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Unique Processing During a Period of High Excitation/Inhibition Balance in Adult-Born Neurons.

Publication Date: 2012 Jan 26 PMID: 22282476
Authors: Marin-Burgin, A. - Mongiat, L. A. - Pardi, M. B. - Schinder, A. F.
Journal: Science

The adult dentate gyrus generates new granule cells (GCs) that develop over several weeks and integrate into the preexisting network. While adult hippocampal neurogenesis has been implicated in learning and memory, the specific role of new GCs remains unclear. We examined whether immature adult-born neurons contribute to information encoding. Combining calcium imaging and electrophysiology in acute slices, we found that weak afferent activity recruits few mature GCs while activating a substantial proportion of the immature neurons. These different activation thresholds are dictated by an enhanced excitation/inhibition balance transiently expressed in immature GCs. Immature GCs exhibit low input specificity that switches with time towards a highly specific responsiveness. Therefore, activity patterns entering the dentate gyrus can undergo differential decoding by a heterogeneous population of GCs originated at different times.

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Epithelial Nitration by a Peroxidase/NOX5 System Mediates Mosquito Antiplasmodial Immunity.

Publication Date: 2012 Jan 26 PMID: 22282475
Authors: Oliveira, G. D. - Lieberman, J. - Barillas-Mury, C.
Journal: Science

Plasmodium ookinetes traverse midgut epithelial cells before they encounter the complement system in the mosquito hemolymph. We identified a heme peroxidase (HPX2) and NADPH oxidase 5 (NOX5) as critical mediators of midgut epithelial nitration and antiplasmodial immunity that enhance nitric oxide toxicity in Anopheles gambiae. We show that the two immune mechanisms that target ookinetes-epithelial nitration and thioester-containing protein 1 (TEP1)-mediated lysis-work sequentially and propose that epithelial nitration works as an opsonization-like system that promotes activation of the mosquito complement cascade.

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Mountains, Weathering, and Climate.

Publication Date: 2012 Jan 26 PMID: 22282474
Authors: Paytan, A.
Journal: Science

Changes in the lithium isotope composition of seawater over the past 70 million years elucidate the links between weathering and climate.

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Lithium Isotope History of Cenozoic Seawater: Changes in Silicate Weathering and Reverse Weathering.

Publication Date: 2012 Jan 26 PMID: 22282473
Authors: Misra, S. - Froelich, P. N.
Journal: Science

Weathering of uplifted continental rocks consumes CO(2) and transports cations to the oceans, playing a critical role in controlling both seawater chemistry and climate. However, there are few archives of seawater chemical change that reveal shifts in global tectonic forces connecting Earth-ocean-climate processes. Here, we present a 68-million-year record of lithium isotopes in seawater (delta(7)Li(SW)) reconstructed from planktonic foraminifera. From the Paleocene (60 Ma) to Present, delta(7)Li(SW) rose 9 per thousand, requiring large changes in continental weathering and seafloor reverse weathering consistent with increased tectonic uplift, more rapid continental denudation, increasingly incongruent continental weathering (lower chemical weathering intensity), and more rapid CO(2) drawdown. A 5 per thousand drop in delta(7)Li(SW) across the Cretaceous-Paleogene boundary cannot be produced by an impactor nor by Deccan trap volcanism, suggesting large-scale continental denudation.

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Evolutionarily Assembled cis-Regulatory Module at a Human Ciliopathy Locus.

Publication Date: 2012 Jan 26 PMID: 22282472
Authors: Lee, J. H. - Silhavy, J. L. - Lee, J. E. - Al-Gazali, L. - Thomas, S. - Davis, E. E. - Bielas, S. L. - Hill, K. J. - Iannicelli, M. - Brancati, F. - Gabriel, S. B. - Russ, C. - Logan, C. V. - Sharif, S. M. - Bennett, C. P. - Abe, M. - Hildebrandt, F. - Diplas, B. H. - Attie-Bitach, T. - Katsanis, N. - Rajab, A. - Koul, R. - Sztriha, L. - Waters, E. R. - Ferro-Novick, S. - Woods, G. C. - Johnson, C. A. - Valente, E. M. - Zaki, M. S. - Gleeson, J. G.
Journal: Science

Neighboring genes are often coordinately expressed within cis-regulatory modules, but evidence that nonparalogous genes share functions in mammals is lacking. Here, we report that mutation of either TMEM138 or TMEM216 causes a phenotypically indistinguishable human ciliopathy, Joubert syndrome. Despite lack of sequence homology, the genes are aligned in a head-to-tail configuration and joined by chromosomal rearrangement at the amphibian to reptile evolutionary transition. Expression of the two genes is mediated by a conserved regulatory element in the noncoding intergenic region. Coordinated expression is important for their interdependent cellular role in vesicular transport to primary cilia. Hence, during vertebrate evolution of genes involved in ciliogenesis, nonparalogous genes were arranged to a functional gene cluster with shared regulatory elements.

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Locally synchronized synaptic inputs.

Publication Date: 2012 Jan 20 PMID: 22267814
Authors: Takahashi, N. - Kitamura, K. - Matsuo, N. - Mayford, M. - Kano, M. - Matsuki, N. - Ikegaya, Y.
Journal: Science

Synaptic inputs on dendrites are nonlinearly converted to action potential outputs, yet the spatiotemporal patterns of dendritic activation remain to be elucidated at single-synapse resolution. In rodents, we optically imaged synaptic activities from hundreds of dendritic spines in hippocampal and neocortical pyramidal neurons ex vivo and in vivo. Adjacent spines were frequently synchronized in spontaneously active networks, thereby forming dendritic foci that received locally convergent inputs from presynaptic cell assemblies. This precise subcellular geometry manifested itself during N-methyl-D-aspartate receptor-dependent circuit remodeling. Thus, clustered synaptic plasticity is innately programmed to compartmentalize correlated inputs along dendrites and may reify nonlinear synaptic integration.

MeSH Categories: Action Potentials, Animals, CA3 Region, Hippocampal/cytology/physiology, Calcium/metabolism, Dendritic Spines/*physiology/ultrastructure, Excitatory Postsynaptic Potentials, Mice, Mice, Inbred C57BL, Mice, Transgenic, Nerve Net/*physiology, Neuronal Plasticity, Organ Culture Techniques, Patch-Clamp Techniques, Pyramidal Cells/*physiology, Rats, Rats, Wistar, Receptors, N-Methyl-D-Aspartate/antagonists & inhibitors/metabolism, Somatosensory Cortex/cytology/physiology, Synapses/*physiology

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Tuning of natural killer cell reactivity by NKp46 and Helios calibrates T cell responses.

Publication Date: 2012 Jan 20 PMID: 22267813
Authors: Narni-Mancinelli, E. - Jaeger, B. N. - Bernat, C. - Fenis, A. - Kung, S. - De Gassart, A. - Mahmood, S. - Gut, M. - Heath, S. C. - Estelle, J. - Bertosio, E. - Vely, F. - Gastinel, L. N. - Beutler, B. - Malissen, B. - Malissen, M. - Gut, I. G. - Vivier, E. - Ugolini, S.
Journal: Science

Natural killer (NK) cells are lymphocytes involved in antimicrobial and antitumoral immune responses. Using N-ethyl-N-nitrosourea mutagenesis in mice, we identified a mutant with increased resistance to viral infections because of the presence of hyperresponsive NK cells. Whole-genome sequencing and functional analysis revealed a loss-of-function mutation in the Ncr1 gene encoding the activating receptor NKp46. The down-regulation of NK cell activity by NKp46 was associated with the silencing of the Helios transcription factor in NK cells. NKp46 was critical for the subsequent development of antiviral and antibacterial T cell responses, which suggests that the regulation of NK cell function by NKp46 allows for the optimal development of adaptive immune responses. NKp46 blockade enhanced NK cell reactivity in vivo, which could enable the design of immunostimulation strategies in humans.

MeSH Categories: Adaptive Immunity, Amino Acid Substitution, Animals, Antibodies, Blocking/immunology, Antibodies, Monoclonal/immunology, Antigens, Ly/genetics/immunology/*physiology, CD8-Positive T-Lymphocytes/immunology, Cell Line, DNA-Binding Proteins/*genetics/physiology, Down-Regulation, Genetic Complementation Test, Herpesviridae Infections/*immunology/virology, Immunologic Memory, Killer Cells, Natural/*immunology, Listeriosis/immunology, Mice, Mice, Inbred C57BL, Mice, Transgenic, Muromegalovirus/physiology, Mutagenesis, Natural Cytotoxicity Triggering Receptor 1/antagonists &, inhibitors/genetics/immunology/*physiology, T-Lymphocytes/*immunology, Transcription Factors/*genetics/physiology, Transcription, Genetic, Viral Load

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Illusions promote mating success in great bowerbirds.

Publication Date: 2012 Jan 20 PMID: 22267812
Authors: Kelley, L. A. - Endler, J. A.
Journal: Science

Sexual selection studies normally compare signal strengths, but signal components and sensory processing may interact to create misleading or attention-capturing illusions. Visual illusions can be produced by altering object and scene geometry in ways that trick the viewer when seen from a particular direction. Male great bowerbirds actively maintain size-distance gradients of objects on their bower courts that create forced-perspective illusions for females viewing their displays from within the bower avenue. We show a significant relationship between mating success and the female's view of the gradient; this view explains substantially more variance in mating success than the strength of the gradients. Illusions may be widespread in other animals because males of most species display to females with characteristic orientation and distance, providing excellent conditions for illusions.

MeSH Categories: Animals, Attention, Female, Male, *Mating Preference, Animal, *Optical Illusions, Passeriformes/*physiology, Reproduction, *Sexual Behavior, Animal, Size Perception, Space Perception

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Manganese blocks intracellular trafficking of Shiga toxin and protects against Shiga toxicosis.

Publication Date: 2012 Jan 20 PMID: 22267811
Authors: Mukhopadhyay, S. - Linstedt, A. D.
Journal: Science

Infections with Shiga toxin (STx)-producing bacteria cause more than a million deaths each year and have no definitive treatment. To exert its cytotoxic effect, STx invades cells through retrograde membrane trafficking, escaping the lysosomal degradative pathway. We found that the widely available metal manganese (Mn(2+)) blocked endosome-to-Golgi trafficking of STx and caused its degradation in lysosomes. Mn(2+) targeted the cycling Golgi protein GPP130, which STx bound in control cells during sorting into Golgi-directed endosomal tubules that bypass lysosomes. In tissue culture cells, treatment with Mn(2+) yielded a protection factor of 3800 against STx-induced cell death. Furthermore, mice injected with nontoxic doses of Mn(2+) were completely resistant to a lethal STx challenge. Thus, Mn(2+) may represent a low-cost therapeutic agent for the treatment of STx infections.

MeSH Categories: Animals, Cell Death, Cell Membrane/metabolism, Endosomes/*metabolism/ultrastructure, Golgi Apparatus/metabolism, HeLa Cells, Humans, Lethal Dose 50, Lysosomes/*metabolism, Manganese/administration & dosage/*pharmacology, Mice, Protein Binding, Protein Transport/drug effects, Shiga Toxin 1/*metabolism/*toxicity, Shiga Toxins/*metabolism/*toxicity, Vesicular Transport Proteins/chemistry/metabolism

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Destruction of Sun-grazing comet C/2011 N3 (SOHO) within the low solar corona.

Publication Date: 2012 Jan 20 PMID: 22267810
Authors: Schrijver, C. J. - Brown, J. C. - Battams, K. - Saint-Hilaire, P. - Liu, W. - Hudson, H. - Pesnell, W. D.
Journal: Science

Observations of comets in Sun-grazing orbits that survive solar insolation long enough to penetrate into the Sun's inner corona provide information on the solar atmosphere and magnetic field as well as on the makeup of the comet. On 6 July 2011, the Solar Dynamics Observatory (SDO) observed the demise of comet C/2011 N3 (SOHO) within the low solar corona in five wavelength bands in the extreme ultraviolet (EUV). The comet penetrated to within 0.146 solar radius (~100,000 kilometers) of the solar surface before its EUV signal disappeared. Before that, material released into the coma--at first seen in absorption--formed a variable EUV-bright tail. During the final 10 minutes of observation by SDO's Atmospheric Imaging Assembly, ~6 x 10(8) to 6 x 10(10) grams of total mass was lost (corresponding to an effective nucleus diameter of ~10 to 50 meters), as estimated from the tail's deceleration due to interaction with the surrounding coronal material; the EUV absorption by the comet and the brightness of the tail suggest that the mass was at the high end of this range. These observations provide evidence that the nucleus had broken up into a family of fragments, resulting in accelerated sublimation in the Sun's intense radiation field.

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Single-molecule lysozyme dynamics monitored by an electronic circuit.

Publication Date: 2012 Jan 20 PMID: 22267809
Authors: Choi, Y. - Moody, I. S. - Sims, P. C. - Hunt, S. R. - Corso, B. L. - Perez, I. - Weiss, G. A. - Collins, P. G.
Journal: Science

Tethering a single lysozyme molecule to a carbon nanotube field-effect transistor produced a stable, high-bandwidth transducer for protein motion. Electronic monitoring during 10-minute periods extended well beyond the limitations of fluorescence techniques to uncover dynamic disorder within a single molecule and establish lysozyme as a processive enzyme. On average, 100 chemical bonds are processively hydrolyzed, at 15-hertz rates, before lysozyme returns to its nonproductive, 330-hertz hinge motion. Statistical analysis differentiated single-step hinge closure from enzyme opening, which requires two steps. Seven independent time scales governing lysozyme's activity were observed. The pH dependence of lysozyme activity arises not from changes to its processive kinetics but rather from increasing time spent in either nonproductive rapid motions or an inactive, closed conformation.

MeSH Categories: Bacteriophage T4/enzymology, Biocatalysis, Electric Conductivity, Fluorescence Resonance Energy Transfer, Hydrogen-Ion Concentration, Kinetics, Microscopy, Atomic Force, Muramidase/*chemistry/*metabolism, Nanotubes, Carbon, Peptidoglycan/metabolism, Protein Conformation, Pyrenes, Static Electricity, Thermodynamics, Transistors, Electronic

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Visualizing gas molecules interacting with supported nanoparticulate catalysts at reaction conditions.

Publication Date: 2012 Jan 20 PMID: 22267808
Authors: Yoshida, H. - Kuwauchi, Y. - Jinschek, J. R. - Sun, K. - Tanaka, S. - Kohyama, M. - Shimada, S. - Haruta, M. - Takeda, S.
Journal: Science

Understanding how molecules can restructure the surfaces of heterogeneous catalysts under reaction conditions requires methods that can visualize atoms in real space and time. We applied a newly developed aberration-corrected environmental transmission electron microscopy to show that adsorbed carbon monoxide (CO) molecules caused the {100} facets of a gold nanoparticle to reconstruct during CO oxidation at room temperature. The CO molecules adsorbed at the on-top sites of gold atoms in the reconstructed surface, and the energetic favorability of this reconstructed structure was confirmed by ab initio calculations and image simulations. This atomic-scale visualizing method can be applied to help elucidate reaction mechanisms in heterogeneous catalysis.

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An engineered microbial platform for direct biofuel production from brown macroalgae.

Publication Date: 2012 Jan 20 PMID: 22267807
Authors: Wargacki, A. J. - Leonard, E. - Win, M. N. - Regitsky, D. D. - Santos, C. N. - Kim, P. B. - Cooper, S. R. - Raisner, R. M. - Herman, A. - Sivitz, A. B. - Lakshmanaswamy, A. - Kashiyama, Y. - Baker, D. - Yoshikuni, Y.
Journal: Science

Prospecting macroalgae (seaweeds) as feedstocks for bioconversion into biofuels and commodity chemical compounds is limited primarily by the availability of tractable microorganisms that can metabolize alginate polysaccharides. Here, we present the discovery of a 36-kilo-base pair DNA fragment from Vibrio splendidus encoding enzymes for alginate transport and metabolism. The genomic integration of this ensemble, together with an engineered system for extracellular alginate depolymerization, generated a microbial platform that can simultaneously degrade, uptake, and metabolize alginate. When further engineered for ethanol synthesis, this platform enables bioethanol production directly from macroalgae via a consolidated process, achieving a titer of 4.7% volume/volume and a yield of 0.281 weight ethanol/weight dry macroalgae (equivalent to ~80% of the maximum theoretical yield from the sugar composition in macroalgae).

MeSH Categories: Alginates/chemistry/*metabolism, Bacterial Proteins/genetics/metabolism, *Biofuels, Biological Transport, Biomass, Carrier Proteins/genetics/metabolism, Escherichia coli/*genetics/metabolism, Ethanol/*metabolism, Fermentation, Genes, Bacterial, Glucose/metabolism, Glucuronic Acid/chemistry/metabolism, Hexuronic Acids/chemistry/metabolism, Lactic Acid/metabolism, Mannitol/metabolism, *Metabolic Engineering, Metabolic Networks and Pathways, Open Reading Frames, Phaeophyta/*metabolism, Polysaccharide-Lyases/genetics/metabolism, Seaweed/*metabolism, Vibrio/*enzymology/genetics

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Demonstration of blind quantum computing.

Publication Date: 2012 Jan 20 PMID: 22267806
Authors: Barz, S. - Kashefi, E. - Broadbent, A. - Fitzsimons, J. F. - Zeilinger, A. - Walther, P.
Journal: Science

Quantum computers, besides offering substantial computational speedups, are also expected to preserve the privacy of a computation. We present an experimental demonstration of blind quantum computing in which the input, computation, and output all remain unknown to the computer. We exploit the conceptual framework of measurement-based quantum computation that enables a client to delegate a computation to a quantum server. Various blind delegated computations, including one- and two-qubit gates and the Deutsch and Grover quantum algorithms, are demonstrated. The client only needs to be able to prepare and transmit individual photonic qubits. Our demonstration is crucial for unconditionally secure quantum cloud computing and might become a key ingredient for real-life applications, especially when considering the challenges of making powerful quantum computers widely available.

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Retrospective. Lynn Margulis (1938-2011).

Publication Date: 2012 Jan 20 PMID: 22267805
Authors: Schaechter, M.
Journal: Science

MeSH Categories: *Biological Evolution, *Eukaryotic Cells, History, 20th Century, History, 21st Century, *Symbiosis, United States

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Biochemistry. Enzymes in coherent motion.

Publication Date: 2012 Jan 20 PMID: 22267804
Authors: Lu, H. P.
Journal: Science

MeSH Categories: Muramidase/*chemistry/*metabolism

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Genetics. Sowing the seeds of centromeres.

Publication Date: 2012 Jan 20 PMID: 22267803
Authors: Jansen, L. E.
Journal: Science

MeSH Categories: Animals, Centromere/*physiology, Drosophila/*genetics, Histones/*physiology

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Geophysics. Transforming earthquake detection?

Publication Date: 2012 Jan 20 PMID: 22267802
Authors: Allen, R. M.
Journal: Science

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Astronomy. The final flight of a Sun-diving comet.

Publication Date: 2012 Jan 20 PMID: 22267801
Authors: Lisse, C. M.
Journal: Science

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Physics. Moving beyond trust in quantum computing.

Publication Date: 2012 Jan 20 PMID: 22267800
Authors: Vedral, V.
Journal: Science

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Cancer. Taking a back door to target Myc.

Publication Date: 2012 Jan 20 PMID: 22267799
Authors: Evan, G.
Journal: Science

MeSH Categories: Animals, Breast Neoplasms/*genetics, *Cell Transformation, Neoplastic, Female, *Genes, myc, Humans, Proto-Oncogene Proteins c-myc/*metabolism, *Transcription, Genetic, Ubiquitin-Activating Enzymes/*genetics

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Psychology. Bird-brained illusionists.

Publication Date: 2012 Jan 20 PMID: 22267798
Authors: Anderson, B. L.
Journal: Science

MeSH Categories: Animals, Female, Male, *Mating Preference, Animal, *Optical Illusions, Passeriformes/*physiology, *Sexual Behavior, Animal

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Agriculture. What next for agriculture after Durban?

Publication Date: 2012 Jan 20 PMID: 22267797
Authors: Beddington, J. R. - Asaduzzaman, M. - Clark, M. E. - Fernandez Bremauntz, A. - Guillou, M. D. - Howlett, D. J. - Jahn, M. M. - Lin, E. - Mamo, T. - Negra, C. - Nobre, C. A. - Scholes, R. J. - Van Bo, N. - Wakhungu, J.
Journal: Science

MeSH Categories: *Agriculture/methods/trends, *Climate Change, Conservation of Natural Resources, Food Supply, Forestry, *Policy Making, United Nations

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Comment on "Probing the ultimate limit of fiber-optic strain sensing".

Publication Date: 2012 Jan 20 PMID: 22267794
Authors: Cranch, G. A. - Foster, S.
Journal: Science

Gagliardi et al. (Reports, 19 November 2010, p. 1081) described an ultrahigh-resolution fiber-optic strain sensor. This comment addresses an error in the calculation of the fundamental thermodynamic noise in optical fiber resonators and shows that the actual thermodynamic noise level is lower by a factor of at least 11 than that calculated.

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Global endemism needs spatial integration.

Publication Date: 2012 Jan 20 PMID: 22267791
Authors: Lei, F. M.
Journal: Science

MeSH Categories: Animals, *Biodiversity, *Climate Change

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Good news for European vultures.

Publication Date: 2012 Jan 20 PMID: 22267790
Authors: Margalida, A. - Carrete, M. - Sanchez-Zapata, J. A. - Donazar, J. A.
Journal: Science

MeSH Categories: Animals, Conservation of Natural Resources/*legislation & jurisprudence, *Ecosystem, *Falconiformes, Spain

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Clinical trials. Experimental cancer therapies move to the front line.

Publication Date: 2012 Jan 20 PMID: 22267789
Authors: Couzin-Frankel, J.
Journal: Science

MeSH Categories: Antineoplastic Agents/*administration & dosage/adverse, effects/*therapeutic use, *Antineoplastic Protocols, Breast Neoplasms/drug therapy, *Clinical Trials as Topic, Drugs, Investigational/*administration & dosage/adverse, effects/therapeutic use, Female, Humans, Lung Neoplasms/drug therapy, Melanoma/drug therapy, Molecular Targeted Therapy, Neoplasms/*drug therapy, Risk Assessment

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Autophagy. Explaining exercise.

Publication Date: 2012 Jan 20 PMID: 22267788
Authors: Garber, K.
Journal: Science

MeSH Categories: AMP-Activated Protein Kinases/metabolism, Animals, *Autophagy, Diabetes Mellitus/physiopathology/therapy, Energy Metabolism, Exercise Therapy, Mice, Mitochondria, Muscle/metabolism, Muscle, Skeletal/*physiology, *Physical Conditioning, Animal, *Physical Exertion, Stress, Physiological

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Archaeologist of sound.

Publication Date: 2012 Jan 20 PMID: 22267787
Authors: Cowen, R.
Journal: Science

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Society for Integrative and Comparative Biology. Clingfish stick like geckos.

Publication Date: 2012 Jan 20 PMID: 22267786
Authors: Pennisi, E.
Journal: Science

MeSH Categories: Adhesiveness, Animal Fins/*anatomy & histology/*physiology, Animals, Biomechanics, Perciformes/*anatomy & histology/*physiology

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Society for Integrative and Comparative Biology. Robotic fish point to schooling gene.

Publication Date: 2012 Jan 20 PMID: 22267785
Authors: Pennisi, E.
Journal: Science

MeSH Categories: Animals, *Behavior, Animal, *Genes, Lateral Line System/anatomy & histology, *Robotics, Smegmamorpha/anatomy & histology/*genetics/*physiology, *Swimming

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Society for Integrative and Comparative Biology. Heads-up on a whale's gulp.

Publication Date: 2012 Jan 20 PMID: 22267784
Authors: Pennisi, E.
Journal: Science

MeSH Categories: Animals, Balaenoptera/*anatomy & histology/*physiology, Biomechanics, Energy Metabolism, *Feeding Behavior, Mouth/physiology, Sense Organs/*anatomy & histology/blood supply/innervation/*physiology, Swimming

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Science Indicators 2012. Report notes China's influence in emerging Asian science zone.

Publication Date: 2012 Jan 20 PMID: 22267783
Authors: Mervis, J.
Journal: Science

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Biofuels. Engineered superbugs boost hopes of turning seaweed into fuel.

Publication Date: 2012 Jan 20 PMID: 22267782
Authors: Stokstad, E.
Journal: Science

MeSH Categories: Alginates/*metabolism, *Biofuels, Escherichia coli/*genetics, Ethanol/*metabolism, Glucuronic Acid/metabolism, Hexuronic Acids/metabolism, *Metabolic Engineering, Phaeophyta/*metabolism, Seaweed/*metabolism, Vibrio/*enzymology

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Seismology. A tantalizing view of what set off Japan's killer quake.

Publication Date: 2012 Jan 20 PMID: 22267781
Authors: Kerr, R. A.
Journal: Science

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Trivializing science education.

Publication Date: 2012 Jan 20 PMID: 22267776
Authors: Alberts, B.
Journal: Science

MeSH Categories: Biology/education, Curriculum, Science/*education

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Pause on Avian Flu Transmission Research.

Publication Date: 2012 Jan 20 PMID: 22267586
Authors: Fouchier, R. A. - Garcia-Sastre, A. - Kawaoka, Y. - Barclay, W. S. - Bouvier, N. M. - Brown, I. H. - Capua, I. - Chen, H. - Compans, R. W. - Couch, R. B. - Cox, N. J. - Doherty, P. C. - Donis, R. O. - Feldmann, H. - Guan, Y. - Katz, J. - Klenk, H. D. - Kobinger, G. - Liu, J. - Liu, X. - Lowen, A. - Mettenleiter, T. C. - Osterhaus, A. D. - Palese, P. - Peiris, J. S. - Perez, D. R. - Richt, J. A. - Schultz-Cherry, S. - Steel, J. - Subbarao, K. - Swayne, D. E. - Takimoto, T. - Tashiro, M. - Taubenberger, J. K. - Thomas, P. G. - Tripp, R. A. - Tumpey, T. M. - Webby, R. J. - Webster, R. G.
Journal: Science

Resulting from concerns about recent research on avian influenza, scientists working on transmission of the H5N1 strain have agreed to halt this area of research for 60 days to allow time for international discussion.Comment on this article at http://scim.ag/zr4XKx.

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H5N1 Debates: Hung Up on the Wrong Questions.

Publication Date: 2012 Jan 19 PMID: 22267585
Authors: Perez, D. R.
Journal: Science

Information related to influenza transmissibility should be published in its entirety.Comment on this article at http://scim.ag/At5pNN.

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Life Sciences at a Crossroads: Respiratory Transmissible H5N1.

Publication Date: 2012 Jan 19 PMID: 22267584
Authors: Osterholm, M. T. - Henderson, D. A.
Journal: Science

Release of details of recent research on affecting influenza transmissibility poses far more risk than any good that might occur.Comment on this article at http://scim.ag/AcKS4g.

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The Limits of Government Regulation of Science.

Publication Date: 2012 Jan 19 PMID: 22267583
Authors: Kraemer, J. D. - Gostin, L. O.
Journal: Science

A transparent institutional review process will balance scientific freedom and national security better than publication restrictions.Comment on this article at http://scim.ag/yVe762.

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Restricted Data on Influenza H5N1 Virus Transmission.

Publication Date: 2012 Jan 19 PMID: 22267582
Authors: Fouchier, R. A. - Herfst, S. - Osterhaus, A. D.
Journal: Science

Authors of a debated flu transmission study discuss why such work is important and should be published.Comment on this article at http://scim.ag/ypjDVx.

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Rescued Tolerant CD8 T Cells Are Preprogrammed to Reestablish the Tolerant State.

Publication Date: 2012 Jan 19 PMID: 22267581
Authors: Schietinger, A. - Delrow, J. J. - Basom, R. S. - Blattman, J. N. - Greenberg, P. D.
Journal: Science

Tolerant self-antigen specific CD8 T cells fail to proliferate in response to antigen, thereby preventing autoimmune disease. Using an in vivo mouse model, we show that tolerant T cells proliferate and become functional under lymphopenic conditions, even in a tolerogenic environment. However, T cell rescue is only transient, with tolerance reimposed upon lymphorepletion even in the absence of tolerogen, challenging the prevailing paradigm that continuous antigen exposure is critical to maintain tolerance. Genome-wide mRNA and microRNA profiling revealed that tolerant T cells have a tolerance-specific gene profile that can be temporarily overridden under lymphopenic conditions but is inevitably reimposed, which suggests epigenetic regulation. These insights into the regulatory mechanisms that maintain or break self-tolerance may lead to new strategies for the treatment of cancer and autoimmunity.

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Biased Signaling Pathways in beta2-Adrenergic Receptor Characterized by 19F-NMR.

Publication Date: 2012 Jan 19 PMID: 22267580
Authors: Liu, J. J. - Horst, R. - Katritch, V. - Stevens, R. C. - Wuthrich, K.
Journal: Science

Extracellular ligand binding to G protein-coupled receptors (GPCRs) modulates G-protein and beta-arrestin signaling by changing the conformational states of the cytoplasmic region of the receptor. Using site-specific (19)F-NMR labels in the beta(2)-adrenergic receptor (beta(2)AR) in complexes with various ligands, we observed that the cytoplasmic ends of helices VI and VII adopt two major conformational states. Changes in the NMR signals reveal that agonist binding primarily shifts the equilibrium toward the G protein-specific active state of helix VI. In contrast, beta-arrestin-biased ligands predominantly impact the conformational states of helix VII. The selective effects of different ligands on the conformational equilibria involving helices VI and VII provide insights into the long-range structural plasticity of beta(2)AR in partial and biased agonist signaling.

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Determination of Noncovalent Docking by IR Spectroscopy of Cold Gas-Phase Complexes.

Publication Date: 2012 Jan 19 PMID: 22267579
Authors: Garand, E. - Kamrath, M. Z. - Jordan, P. A. - Wolk, A. B. - Leavitt, C. M. - McCoy, A. B. - Miller, S. J. - Johnson, M. A.
Journal: Science

Multidentate, noncovalent interactions between small molecules and biopolymer fragments are central to processes ranging from drug action to selective catalysis. We present a versatile and sensitive spectroscopic probe of functional groups engaged in hydrogen bonding in such contexts. This involves measurement of the frequency changes in specific covalent bonds upon complex formation, information drawn from otherwise transient complexes that have been extracted from solution and conformationally frozen near 10 Kelvin in gas-phase clusters. Resonances closely associated with individual oscillators are easily identified through site-specific isotopic labeling, as demonstrated by application of the method to an archetypal system involving a synthetic tripeptide known to bind biaryl substrates through tailored H-bonding to catalyze their asymmetric bromination. With such data, calculations readily converge on the plausible operative structures in otherwise computationally prohibitive, high-dimensionality landscapes.

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Propagation of Slow Slip Leading Up to the 2011 Mw 9.0 Tohoku-Oki Earthquake.

Publication Date: 2012 Jan 19 PMID: 22267578
Authors: Kato, A. - Obara, K. - Igarashi, T. - Tsuruoka, H. - Nakagawa, S. - Hirata, N.
Journal: Science

Many large earthquakes are preceded by one or more foreshocks, but it is unclear how these foreshocks relate to the nucleation process of the mainshock. On the basis of an earthquake catalog created using a waveform correlation technique, we identified two distinct sequences of foreshocks migrating at rates of 2 to 10 km/day along the trench axis toward the epicenter of the 2011 M(w) 9.0 Tohoku-Oki earthquake. The time history of quasistatic slip along the plate interface, based on small repeating earthquakes that were part of the migrating seismicity, suggests that two sequences involved slow slip transients propagating toward the initial rupture point. The second sequence, which involved large slip rates, may have caused substantial stress loading, prompting the unstable dynamic rupture of the mainshock.

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Erasure of a spinal memory trace of pain by a brief, high-dose opioid administration.

Publication Date: 2012 Jan 13 PMID: 22246779
Authors: Drdla-Schutting, R. - Benrath, J. - Wunderbaldinger, G. - Sandkuhler, J.
Journal: Science

Painful stimuli activate nociceptive C fibers and induce synaptic long-term potentiation (LTP) at their spinal terminals. LTP at C-fiber synapses represents a cellular model for pain amplification (hyperalgesia) and for a memory trace of pain. mu-Opioid receptor agonists exert a powerful but reversible depression at C-fiber synapses that renders the continuous application of low opioid doses the gold standard in pain therapy. We discovered that brief application of a high opioid dose reversed various forms of activity-dependent LTP at C-fiber synapses. Depotentiation involved Ca(2+)-dependent signaling and normalization of the phosphorylation state of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors. This also reversed hyperalgesia in behaving animals. Opioids thus not only temporarily dampen pain but may also erase a spinal memory trace of pain.

MeSH Categories: Analgesics, Opioid/*administration & dosage, Animals, Calcium Signaling, Evoked Potentials, Hyperalgesia/chemically induced/drug therapy, Long-Term Potentiation/*drug effects, Male, Naloxone/administration & dosage, Nerve Fibers, Unmyelinated/*drug effects/physiology, Nociceptive Pain/*drug therapy/physiopathology, Phosphorylation, Piperidines/*administration & dosage, Protein Kinase C/antagonists & inhibitors/metabolism, Protein Phosphatase 1/antagonists & inhibitors/metabolism, Rats, Rats, Sprague-Dawley, Receptors, AMPA/metabolism, Receptors, Opioid, mu/agonists/metabolism, Sciatic Nerve/*drug effects/physiology, Somatostatin/administration & dosage/analogs & derivatives, Spinal Cord/physiology, Synapses/*drug effects/physiology

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iRhom2 regulation of TACE controls TNF-mediated protection against Listeria and responses to LPS.

Publication Date: 2012 Jan 13 PMID: 22246778
Authors: McIlwain, D. R. - Lang, P. A. - Maretzky, T. - Hamada, K. - Ohishi, K. - Maney, S. K. - Berger, T. - Murthy, A. - Duncan, G. - Xu, H. C. - Lang, K. S. - Haussinger, D. - Wakeham, A. - Itie-Youten, A. - Khokha, R. - Ohashi, P. S. - Blobel, C. P. - Mak, T. W.
Journal: Science

Innate immune responses are vital for pathogen defense but can result in septic shock when excessive. A key mediator of septic shock is tumor necrosis factor-alpha (TNFalpha), which is shed from the plasma membrane after cleavage by the TNFalpha convertase (TACE). We report that the rhomboid family member iRhom2 interacted with TACE and regulated TNFalpha shedding. iRhom2 was critical for TACE maturation and trafficking to the cell surface in hematopoietic cells. Gene-targeted iRhom2-deficient mice showed reduced serum TNFalpha in response to lipopolysaccharide (LPS) and could survive a lethal LPS dose. Furthermore, iRhom2-deficient mice failed to control the replication of Listeria monocytogenes. Our study has identified iRhom2 as a regulator of innate immunity that may be an important target for modulating sepsis and pathogen defense.

MeSH Categories: ADAM Proteins/genetics/*metabolism, Amino Acid Sequence, Animals, B-Lymphocytes/immunology/metabolism, Base Sequence, Carrier Proteins/chemistry/genetics/*metabolism, Cell Line, Cell Membrane/metabolism, Gene Deletion, *Immunity, Innate, Lipopolysaccharides/*immunology, Listeria monocytogenes/immunology/physiology, Listeriosis/*immunology/metabolism/microbiology/pathology, Macrophages/immunology/metabolism, Macrophages, Peritoneal/immunology/metabolism/microbiology, Mice, Molecular Sequence Data, Protein Transport, Shock, Septic/*immunology/metabolism, Spleen/cytology, Tumor Necrosis Factor-alpha/blood/genetics/*metabolism

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Tumor necrosis factor signaling requires iRhom2 to promote trafficking and activation of TACE.

Publication Date: 2012 Jan 13 PMID: 22246777
Authors: Adrain, C. - Zettl, M. - Christova, Y. - Taylor, N. - Freeman, M.
Journal: Science

The cytokine tumor necrosis factor (TNF) is the primary trigger of inflammation. Like many extracellular signaling proteins, TNF is synthesized as a transmembrane protein; the active signal is its ectodomain, which is shed from cells after cleavage by an ADAM family metalloprotease, ADAM17 (TNFalpha-converting enzyme, TACE). We report that iRhom2 (RHBDF2), a proteolytically inactive member of the rhomboid family, is required for TNF release in mice. iRhom2 binds TACE and promotes its exit from the endoplasmic reticulum. The failure of TACE to exit the endoplasmic reticulum in the absence of iRhom2 prevents the furin-mediated maturation and trafficking of TACE to the cell surface, the site of TNF cleavage. Given the role of TNF in autoimmune and inflammatory diseases, iRhom2 may represent an attractive therapeutic target.

MeSH Categories: ADAM Proteins/*metabolism, Animals, Carrier Proteins/genetics/*metabolism, Cell Line, Cell Membrane/metabolism, Endoplasmic Reticulum/metabolism, Enzyme Activation, Furin/metabolism, Humans, Lipopolysaccharides/immunology, Macrophages/metabolism, Mice, Mice, Knockout, Protein Binding, Protein Transport, *Signal Transduction, Tumor Necrosis Factor-alpha/*metabolism

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A DOC2 protein identified by mutational profiling is essential for apicomplexan parasite exocytosis.

Publication Date: 2012 Jan 13 PMID: 22246776
Authors: Farrell, A. - Thirugnanam, S. - Lorestani, A. - Dvorin, J. D. - Eidell, K. P. - Ferguson, D. J. - Anderson-White, B. R. - Duraisingh, M. T. - Marth, G. T. - Gubbels, M. J.
Journal: Science

Exocytosis is essential to the lytic cycle of apicomplexan parasites and required for the pathogenesis of toxoplasmosis and malaria. DOC2 proteins recruit the membrane fusion machinery required for exocytosis in a Ca(2+)-dependent fashion. Here, the phenotype of a Toxoplasma gondii conditional mutant impaired in host cell invasion and egress was pinpointed to a defect in secretion of the micronemes, an apicomplexan-specific organelle that contains adhesion proteins. Whole-genome sequencing identified the etiological point mutation in TgDOC2.1. A conditional allele of the orthologous gene engineered into Plasmodium falciparum was also defective in microneme secretion. However, the major effect was on invasion, suggesting that microneme secretion is dispensable for Plasmodium egress.

MeSH Categories: Amino Acid Sequence, Calcium/*metabolism, Calcium-Binding Proteins/chemistry/genetics/*metabolism, Cell Line, *Exocytosis, Genes, Protozoan, Genetic Complementation Test, Genome, Protozoan, Humans, Models, Molecular, Molecular Sequence Data, Movement, Mutagenesis, Organelles/*metabolism, Plasmodium falciparum/genetics/growth & development/physiology, Point Mutation, Protein Structure, Tertiary, Protozoan Proteins/chemistry/genetics/*metabolism, Recombinant Fusion Proteins/metabolism, Toxoplasma/genetics/growth & development/*physiology/ultrastructure

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Plant species richness and ecosystem multifunctionality in global drylands.

Publication Date: 2012 Jan 13 PMID: 22246775
Authors: Maestre, F. T. - Quero, J. L. - Gotelli, N. J. - Escudero, A. - Ochoa, V. - Delgado-Baquerizo, M. - Garcia-Gomez, M. - Bowker, M. A. - Soliveres, S. - Escolar, C. - Garcia-Palacios, P. - Berdugo, M. - Valencia, E. - Gozalo, B. - Gallardo, A. - Aguilera, L. - Arredondo, T. - Blones, J. - Boeken, B. - Bran, D. - Conceicao, A. A. - Cabrera, O. - Chaieb, M. - Derak, M. - Eldridge, D. J. - Espinosa, C. I. - Florentino, A. - Gaitan, J. - Gatica, M. G. - Ghiloufi, W. - Gomez-Gonzalez, S. - Gutierrez, J. R. - Hernandez, R. M. - Huang, X. - Huber-Sannwald, E. - Jankju, M. - Miriti, M. - Monerris, J. - Mau, R. L. - Morici, E. - Naseri, K. - Ospina, A. - Polo, V. - Prina, A. - Pucheta, E. - Ramirez-Collantes, D. A. - Romao, R. - Tighe, M. - Torres-Diaz, C. - Val, J. - Veiga, J. P. - Wang, D. - Zaady, E.
Journal: Science

Experiments suggest that biodiversity enhances the ability of ecosystems to maintain multiple functions, such as carbon storage, productivity, and the buildup of nutrient pools (multifunctionality). However, the relationship between biodiversity and multifunctionality has never been assessed globally in natural ecosystems. We report here on a global empirical study relating plant species richness and abiotic factors to multifunctionality in drylands, which collectively cover 41% of Earth's land surface and support over 38% of the human population. Multifunctionality was positively and significantly related to species richness. The best-fitting models accounted for over 55% of the variation in multifunctionality and always included species richness as a predictor variable. Our results suggest that the preservation of plant biodiversity is crucial to buffer negative effects of climate change and desertification in drylands.

MeSH Categories: *Biodiversity, *Climate, Climate Change, Conservation of Natural Resources, *Ecosystem, Geography, Geological Phenomena, Models, Statistical, *Plants, Regression Analysis, Temperature

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Changes in wind pattern alter albatross distribution and life-history traits.

Publication Date: 2012 Jan 13 PMID: 22246774
Authors: Weimerskirch, H. - Louzao, M. - de Grissac, S. - Delord, K.
Journal: Science

Westerly winds in the Southern Ocean have increased in intensity and moved poleward. Using long-term demographic and foraging records, we show that foraging range in wandering albatrosses has shifted poleward in conjunction with these changes in wind pattern, while their rates of travel and flight speeds have increased. Consequently, the duration of foraging trips has decreased, breeding success has improved, and birds have increased in mass by more than 1 kilogram. These positive consequences of climate change may be temporary if patterns of wind in the southern westerlies follow predicted climate change scenarios. This study stresses the importance of foraging performance as the key link between environmental changes and population processes.

MeSH Categories: Animals, Birds/anatomy & histology/*physiology, Body Size, Body Weight, Climate Change, Environment, Feeding Behavior, Female, *Flight, Animal, Geography, Male, Oceans and Seas, Population Dynamics, Reproduction, Time Factors, *Wind

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Direct kinetic measurements of Criegee intermediate (CHOO) formed by reaction of CHI with O.

Publication Date: 2012 Jan 13 PMID: 22246773
Authors: Welz, O. - Savee, J. D. - Osborn, D. L. - Vasu, S. S. - Percival, C. J. - Shallcross, D. E. - Taatjes, C. A.
Journal: Science

Ozonolysis is a major tropospheric removal mechanism for unsaturated hydrocarbons and proceeds via "Criegee intermediates"--carbonyl oxides--that play a key role in tropospheric oxidation models. However, until recently no gas-phase Criegee intermediate had been observed, and indirect determinations of their reaction kinetics gave derived rate coefficients spanning orders of magnitude. Here, we report direct photoionization mass spectrometric detection of formaldehyde oxide (CH(2)OO) as a product of the reaction of CH(2)I with O(2). This reaction enabled direct laboratory determinations of CH(2)OO kinetics. Upper limits were extracted for reaction rate coefficients with NO and H(2)O. The CH(2)OO reactions with SO(2) and NO(2) proved unexpectedly rapid and imply a substantially greater role of carbonyl oxides in models of tropospheric sulfate and nitrate chemistry than previously assumed.

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Composites reinforced in three dimensions by using low magnetic fields.

Publication Date: 2012 Jan 13 PMID: 22246772
Authors: Erb, R. M. - Libanori, R. - Rothfuchs, N. - Studart, A. R.
Journal: Science

The orientation and distribution of reinforcing particles in artificial composites are key to enable effective reinforcement of the material in mechanically loaded directions, but remain poor if compared to the distinctive architectures present in natural structural composites such as teeth, bone, and seashells. We show that micrometer-sized reinforcing particles coated with minimal concentrations of superparamagnetic nanoparticles (0.01 to 1 volume percent) can be controlled by using ultralow magnetic fields (1 to 10 milliteslas) to produce synthetic composites with tuned three-dimensional orientation and distribution of reinforcements. A variety of structures can be achieved with this simple method, leading to composites with tailored local reinforcement, wear resistance, and shape memory effects.

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Bistability in atomic-scale antiferromagnets.

Publication Date: 2012 Jan 13 PMID: 22246771
Authors: Loth, S. - Baumann, S. - Lutz, C. P. - Eigler, D. M. - Heinrich, A. J.
Journal: Science

Control of magnetism on the atomic scale is becoming essential as data storage devices are miniaturized. We show that antiferromagnetic nanostructures, composed of just a few Fe atoms on a surface, exhibit two magnetic states, the Neel states, that are stable for hours at low temperature. For the smallest structures, we observed transitions between Neel states due to quantum tunneling of magnetization. We sensed the magnetic states of the designed structures using spin-polarized tunneling and switched between them electrically with nanosecond speed. Tailoring the properties of neighboring antiferromagnetic nanostructures enables a low-temperature demonstration of dense nonvolatile storage of information.

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Universal signatures of fractionalized quantum critical points.

Publication Date: 2012 Jan 13 PMID: 22246770
Authors: Isakov, S. V. - Melko, R. G. - Hastings, M. B.
Journal: Science

Ground states of certain materials can support exotic excitations with a charge equal to a fraction of the fundamental electron charge. The condensation of these fractionalized particles has been predicted to drive unusual quantum phase transitions. Through numerical and theoretical analysis of a physical model of interacting lattice bosons, we establish the existence of such an exotic critical point, called XY*. We measure a highly nonclassical critical exponent eta = 1.493 and construct a universal scaling function of winding number distributions that directly demonstrates the distinct topological sectors of an emergent Z(2) gauge field. The universal quantities used to establish this exotic transition can be used to detect other fractionalized quantum critical points in future model and material systems.

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Periodic emission from the gamma-ray binary 1FGL J1018.6-5856.

Publication Date: 2012 Jan 13 PMID: 22246769
Authors: Fermi, L. A. T. Collaboration - Ackermann, M. - Ajello, M. - Ballet, J. - Barbiellini, G. - Bastieri, D. - Belfiore, A. - Bellazzini, R. - Berenji, B. - Blandford, R. D. - Bloom, E. D. - Bonamente, E. - Borgland, A. W. - Bregeon, J. - Brigida, M. - Bruel, P. - Buehler, R. - Buson, S. - Caliandro, G. A. - Cameron, R. A. - Caraveo, P. A. - Cavazzuti, E. - Cecchi, C. - Celik, O. - Charles, E. - Chaty, S. - Chekhtman, A. - Cheung, C. C. - Chiang, J. - Ciprini, S. - Claus, R. - Cohen-Tanugi, J. - Corbel, S. - Corbet, R. H. - Cutini, S. - de Luca, A. - den Hartog, P. R. - de Palma, F. - Dermer, C. D. - Digel, S. W. - do Couto e Silva, E. - Donato, D. - Drell, P. S. - Drlica-Wagner, A. - Dubois, R. - Dubus, G. - Favuzzi, C. - Fegan, S. J. - Ferrara, E. C. - Focke, W. B. - Fortin, P. - Fukazawa, Y. - Funk, S. - Fusco, P. - Gargano, F. - Gasparrini, D. - Gehrels, N. - Germani, S. - Giglietto, N. - Giordano, F. - Giroletti, M. - Glanzman, T. - Godfrey, G. - Grenier, I. A. - Grove, J. E. - Guiriec, S. - Hadasch, D. - Hanabata, Y. - Harding, A. K. - Hayashida, M. - Hays, E. - Hill, A. B. - Hughes, R. E. - Johannesson, G. - Johnson, A. S. - Johnson, T. J. - Kamae, T. - Katagiri, H. - Kataoka, J. - Kerr, M. - Knodlseder, J. - Kuss, M. - Lande, J. - Longo, F. - Loparco, F. - Lovellette, M. N. - Lubrano, P. - Mazziotta, M. N. - McEnery, J. E. - Michelson, P. F. - Mitthumsiri, W. - Mizuno, T. - Monte, C. - Monzani, M. E. - Morselli, A. - Moskalenko, I. V. - Murgia, S. - Nakamori, T. - Naumann-Godo, M. - Norris, J. P. - Nuss, E. - Ohno, M. - Ohsugi, T. - Okumura, A. - Omodei, N. - Orlando, E. - Ozaki, M. - Paneque, D. - Parent, D. - Pesce-Rollins, M. - Pierbattista, M. - Piron, F. - Pivato, G. - Porter, T. A. - Raino, S. - Rando, R. - Razzano, M. - Reimer, A. - Reimer, O. - Ritz, S. - Romani, R. W. - Roth, M. - Saz Parkinson, P. M. - Sgro, C. - Siskind, E. J. - Spandre, G. - Spinelli, P. - Suson, D. J. - Takahashi, H. - Tanaka, T. - Thayer, J. G. - Thayer, J. B. - Thompson, D. J. - Tibaldo, L. - Tinivella, M. - Torres, D. F. - Tosti, G. - Troja, E. - Uchiyama, Y. - Usher, T. L. - Vandenbroucke, J. - Vianello, G. - Vitale, V. - Waite, A. P. - Winer, B. L. - Wood, K. S. - Wood, M. - Yang, Z. - Zimmer, S. - Coe, M. J. - Di Mille, F. - Edwards, P. G. - Filipovic, M. D. - Payne, J. L. - Stevens, J. - Torres, M. A.
Journal: Science

Gamma-ray binaries are stellar systems containing a neutron star or black hole, with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our Galaxy. A search for gamma-ray binaries with the Fermi Large Area Telescope (LAT) shows that 1FGL J1018.6-5856 exhibits intensity and spectral modulation with a 16.6-day period. We identified a variable x-ray counterpart, which shows a sharp maximum coinciding with maximum gamma-ray emission, as well as an O6V((f)) star optical counterpart and a radio counterpart that is also apparently modulated on the orbital period. 1FGL J1018.6-5856 is thus a gamma-ray binary, and its detection suggests the presence of other fainter binaries in the Galaxy.

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Simultaneously mitigating near-term climate change and improving human health and food security.

Publication Date: 2012 Jan 13 PMID: 22246768
Authors: Shindell, D. - Kuylenstierna, J. C. - Vignati, E. - van Dingenen, R. - Amann, M. - Klimont, Z. - Anenberg, S. C. - Muller, N. - Janssens-Maenhout, G. - Raes, F. - Schwartz, J. - Faluvegi, G. - Pozzoli, L. - Kupiainen, K. - Hoglund-Isaksson, L. - Emberson, L. - Streets, D. - Ramanathan, V. - Hicks, K. - Oanh, N. T. - Milly, G. - Williams, M. - Demkine, V. - Fowler, D.
Journal: Science

Tropospheric ozone and black carbon (BC) contribute to both degraded air quality and global warming. We considered ~400 emission control measures to reduce these pollutants by using current technology and experience. We identified 14 measures targeting methane and BC emissions that reduce projected global mean warming ~0.5 degrees C by 2050. This strategy avoids 0.7 to 4.7 million annual premature deaths from outdoor air pollution and increases annual crop yields by 30 to 135 million metric tons due to ozone reductions in 2030 and beyond. Benefits of methane emissions reductions are valued at $700 to $5000 per metric ton, which is well above typical marginal abatement costs (less than $250). The selected controls target different sources and influence climate on shorter time scales than those of carbon dioxide-reduction measures. Implementing both substantially reduces the risks of crossing the 2 degrees C threshold.

MeSH Categories: Aerosols, *Air Pollutants/analysis, Air Pollution/*prevention & control, *Climate Change, Computer Simulation, Cost-Benefit Analysis, *Food Supply, *Health, Humans, *Methane/analysis, Mortality, Premature, *Ozone/analysis, *Soot/analysis

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Bubblegrams reveal the inner body of bacteriophage phiKZ.

Publication Date: 2012 Jan 13 PMID: 22246767
Authors: Wu, W. - Thomas, J. A. - Cheng, N. - Black, L. W. - Steven, A. C.
Journal: Science

Dense packing of macromolecules in cellular compartments and higher-order assemblies makes it difficult to pick out even quite large components in electron micrographs, despite nominally high resolution. Immunogold labeling and histochemical procedures offer ways to map certain components but are limited in their applicability. Here, we present a differential mapping procedure, based on the physical principle of protein's greater sensitivity to radiation damage compared with that of nucleic acid.

MeSH Categories: Capsid/*ultrastructure, Cryoelectron Microscopy, DNA, Viral, Image Processing, Computer-Assisted, Nucleocapsid/ultrastructure, Pseudomonas Phages/*chemistry/radiation effects/*ultrastructure, Viral Proteins/*analysis

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Retrospective. Paul Mead Doty (1920-2011).

Publication Date: 2012 Jan 13 PMID: 22246766
Authors: Meselson, M.
Journal: Science

MeSH Categories: Chemistry/history, DNA/chemistry, History, 20th Century, History, 21st Century, Internationality, Molecular Biology/history, Nucleic Acid Conformation, Nucleic Acid Renaturation, United States

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Cell biology. Sheddase gets guidance.

Publication Date: 2012 Jan 13 PMID: 22246765
Authors: Lichtenthaler, S. F.
Journal: Science

MeSH Categories: ADAM Proteins/*metabolism, Animals, Carrier Proteins/*metabolism, Humans, *Immunity, Innate, Lipopolysaccharides/*immunology, Listeriosis/*immunology, Shock, Septic/*immunology, *Signal Transduction, Tumor Necrosis Factor-alpha/*metabolism

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Chemistry. An elusive intermediate gets caught.

Publication Date: 2012 Jan 13 PMID: 22246764
Authors: Marston, G.
Journal: Science

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Materials science. A composite matter of alignment.

Publication Date: 2012 Jan 13 PMID: 22246763
Authors: Fratzl, P.
Journal: Science

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Astronomy. Gamma-ray binaries revealed.

Publication Date: 2012 Jan 13 PMID: 22246762
Authors: Mirabel, I. F.
Journal: Science

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Ecology. Biodiversity and ecosystem function.

Publication Date: 2012 Jan 13 PMID: 22246761
Authors: Midgley, G. F.
Journal: Science

MeSH Categories: *Biodiversity, *Climate, *Ecosystem, *Plants

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Plant science. SWEET! The pathway is complete.

Publication Date: 2012 Jan 13 PMID: 22246760
Authors: Braun, D. M.
Journal: Science

MeSH Categories: Animals, Arabidopsis/*metabolism, Arabidopsis Proteins/*metabolism, Humans, Membrane Transport Proteins/*metabolism, Phloem/*metabolism, Sucrose/*metabolism

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Education. Better research needed on the impact of charter schools.

Publication Date: 2012 Jan 13 PMID: 22246759
Authors: Betts, J. R. - Atkinson, R. C.
Journal: Science

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Comment on "Late Mousterian persistence near the Arctic Circle".

Publication Date: 2012 Jan 13 PMID: 22246757
Authors: Zwyns, N. - Roebroeks, W. - McPherron, S. P. - Jagich, A. - Hublin, J. J.
Journal: Science

Slimak et al. (Reports, 13 May 2011, p. 841) reanalyzed the lithic assemblage from the northern site of Byzovaya (Russia) and concluded that it was Mousterian and produced by Neandertals. The previous interpretation of this assemblage as falling within Early Upper Paleolithic variability remains the most parsimonious explanation; pending additional fossil discoveries, there is no evidence supporting the occurrence of Neandertals at these high latitudes.

MeSH Categories: Animals, *Archaeology, *Hominidae, Humans

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Single-sex education: parameters too narrow.

Publication Date: 2012 Jan 13 PMID: 22246754
Authors: Palaima, T. G.
Journal: Science

MeSH Categories: Brain/*physiology, Education/*methods/*standards, Female, Humans, *Learning, Male, *Sex Characteristics

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Single-sex education: unequal to segregation.

Publication Date: 2012 Jan 13 PMID: 22246753
Authors: Ford, B.
Journal: Science

MeSH Categories: Brain/*physiology, Education/*methods/*standards, Female, Humans, *Learning, Male, *Sex Characteristics

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Single-sex education: positive effects.

Publication Date: 2012 Jan 13 PMID: 22246752
Authors: Park, H. - Behrman, J. R. - Choi, J.
Journal: Science

MeSH Categories: Brain/*physiology, Education/*methods/*standards, Female, Humans, *Learning, Male, *Sex Characteristics

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Single-sex education: results one-sided.

Publication Date: 2012 Jan 13 PMID: 22246751
Authors: Kalkus, O. A.
Journal: Science

MeSH Categories: Brain/*physiology, Education/*methods/*standards, Female, Humans, *Learning, Male, *Sex Characteristics

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Materials Research Society's fall meeting and exhibit. Al bids to vie with Li in battery wars.

Publication Date: 2012 Jan 13 PMID: 22246750
Authors: Service, R. F.
Journal: Science

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Materials Research Society's fall meeting and exhibit. Snapshots from the meeting.

Publication Date: 2012 Jan 13 PMID: 22246749
Authors: Service, R. F.
Journal: Science

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Materials Research Society's fall meeting and exhibit. New lease for leftover light.

Publication Date: 2012 Jan 13 PMID: 22246748
Authors: Service, R. F.
Journal: Science

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Archaeology. The peopling of the Aleutians.

Publication Date: 2012 Jan 13 PMID: 22246747
Authors: Balter, M.
Journal: Science

MeSH Categories: Alaska, Archaeology, DNA, Mitochondrial/genetics, Emigration and Immigration, Haplotypes, Humans, *Inuits/genetics, Population Dynamics

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Newsmaker interview: C. N. R. Rao. Top Indian chemist helps make the case for science windfall. Interview by Pallava Bagla.

Publication Date: 2012 Jan 13 PMID: 22246746
Authors: Rao, C. N.
Journal: Science

MeSH Categories: India, *Research Personnel, *Science/manpower

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Global change. A quick (partial) fix for an ailing atmosphere.

Publication Date: 2012 Jan 13 PMID: 22246745
Authors: Kerr, R. A.
Journal: Science

MeSH Categories: *Air Pollutants, Air Pollution/*prevention & control, *Climate Change, *Food Supply, *Health, Humans, *Methane, *Ozone, *Soot

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Ground-based astronomy. Pleading poverty, NSF delays plans for giant telescope.

Publication Date: 2012 Jan 13 PMID: 22246744
Authors: Bhattacharjee, Y.
Journal: Science

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China. Tobacco scientist's election tars academy's image.

Publication Date: 2012 Jan 13 PMID: 22246743
Authors: Hvistendahl, M.
Journal: Science

MeSH Categories: Academies and Institutes/*organization & administration, China/epidemiology, *Engineering, Humans, International Cooperation, Research, Research Support as Topic, *Smoking/epidemiology, *Tobacco Industry/economics

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It's the teachers.

Publication Date: 2012 Jan 13 PMID: 22246738
Authors: Burris, J. E.
Journal: Science

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High-latitude forcing of the South American summer monsoon during the Last Glacial.

Publication Date: 2012 Feb 3 PMID: 22245741
Authors: Kanner, L. C. - Burns, S. J. - Cheng, H. - Edwards, R. L.
Journal: Science

The climate of the Last Glacial period (10,000 to 110,000 years ago) was characterized by rapid millennial-scale climate fluctuations termed Dansgaard/Oeschger (D/O) and Heinrich events. We present results from a speleothem-derived proxy of the South American summer monsoon (SASM) from 16,000 to 50,000 years ago that demonstrate the occurrence of D/O cycles and Heinrich events. This tropical Southern Hemisphere monsoon reconstruction illustrates an antiphase relationship to Northern Hemisphere monsoon intensity at the millennial scale. Our results also show an influence of Antarctic millennial-scale climate fluctuations on the SASM. This high-resolution, precisely dated, tropical precipitation record can be used to establish the timing of climate events in the high latitudes of the Northern and Southern Hemispheres.

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Female leadership raises aspirations and educational attainment for girls: a policy experiment in India.

Publication Date: 2012 Feb 3 PMID: 22245740
Authors: Beaman, L. - Duflo, E. - Pande, R. - Topalova, P.
Journal: Science

Exploiting a randomized natural experiment in India, we show that female leadership influences adolescent girls' career aspirations and educational attainment. A 1993 law reserved leadership positions for women in randomly selected village councils. Using 8453 surveys of adolescents aged 11 to 15 and their parents in 495 villages, we found that, relative to villages in which such positions were never reserved, the gender gap in aspirations closed by 20% in parents and 32% in adolescents in villages assigned a female leader for two election cycles. The gender gap in adolescent educational attainment was erased, and girls spent less time on household chores. We found no evidence of changes in young women's labor market opportunities, which suggests that the impact of women leaders primarily reflects a role model effect.

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Revealing the superfluid lambda transition in the universal thermodynamics of a unitary Fermi gas.

Publication Date: 2012 Feb 3 PMID: 22245739
Authors: Ku, M. J. - Sommer, A. T. - Cheuk, L. W. - Zwierlein, M. W.
Journal: Science

Fermi gases, collections of fermions such as neutrons and electrons, are found throughout nature, from solids to neutron stars. Interacting Fermi gases can form a superfluid or, for charged fermions, a superconductor. We have observed the superfluid phase transition in a strongly interacting Fermi gas by high-precision measurements of the local compressibility, density, and pressure. Our data completely determine the universal thermodynamics of these gases without any fit or external thermometer. The onset of superfluidity is observed in the compressibility, the chemical potential, the entropy, and the heat capacity, which displays a characteristic lambda-like feature at the critical temperature T(c)/T(F) = 0.167(13). The ground-state energy is 3/5xiN E(F) with xi = 0.376(4). Our measurements provide a benchmark for many-body theories of strongly interacting fermions.

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Innate response activator B cells protect against microbial sepsis.

Publication Date: 2012 Feb 3 PMID: 22245738
Authors: Rauch, P. J. - Chudnovskiy, A. - Robbins, C. S. - Weber, G. F. - Etzrodt, M. - Hilgendorf, I. - Tiglao, E. - Figueiredo, J. L. - Iwamoto, Y. - Theurl, I. - Gorbatov, R. - Waring, M. T. - Chicoine, A. T. - Mouded, M. - Pittet, M. J. - Nahrendorf, M. - Weissleder, R. - Swirski, F. K.
Journal: Science

Recognition and clearance of a bacterial infection are a fundamental properties of innate immunity. Here, we describe an effector B cell population that protects against microbial sepsis. Innate response activator (IRA) B cells are phenotypically and functionally distinct, develop and diverge from B1a B cells, depend on pattern-recognition receptors, and produce granulocyte-macrophage colony-stimulating factor. Specific deletion of IRA B cell activity impairs bacterial clearance, elicits a cytokine storm, and precipitates septic shock. These observations enrich our understanding of innate immunity, position IRA B cells as gatekeepers of bacterial infection, and identify new treatment avenues for infectious diseases.

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Langerhans cells facilitate epithelial DNA damage and squamous cell carcinoma.

Publication Date: 2012 Jan 6 PMID: 22223807
Authors: Modi, B. G. - Neustadter, J. - Binda, E. - Lewis, J. - Filler, R. B. - Roberts, S. J. - Kwong, B. Y. - Reddy, S. - Overton, J. D. - Galan, A. - Tigelaar, R. - Cai, L. - Fu, P. - Shlomchik, M. - Kaplan, D. H. - Hayday, A. - Girardi, M.
Journal: Science

Polyaromatic hydrocarbons (PAHs) are prevalent, potent carcinogens, and 7,12-dimethylbenz[a]anthracene (DMBA) is a model PAH widely used to study tumorigenesis. Mice lacking Langerhans cells (LCs), a signatory epidermal dendritic cell (DC), are protected from cutaneous chemical carcinogenesis, independent of T cell immunity. Investigation of the underlying mechanism revealed that LC-deficient skin was relatively resistant to DMBA-induced DNA damage. LCs efficiently metabolized DMBA to DMBA-trans-3,4-diol, an intermediate proximal to oncogenic Hras mutation, and DMBA-treated LC-deficient skin contained significantly fewer Hras mutations. Moreover, DMBA-trans-3,4-diol application bypassed tumor resistance in LC-deficient mice. Additionally, the genotoxic impact of DMBA on human keratinocytes was significantly increased by prior incubation with human-derived LC. Thus, tissue-associated DC can enhance chemical carcinogenesis via PAH metabolism, highlighting the complex relation between immune cells and carcinogenesis.

MeSH Categories: 9,10-Dimethyl-1,2-benzanthracene/*analogs &, derivatives/metabolism/toxicity, Animals, Aryl Hydrocarbon Hydroxylases/metabolism, Carcinogens/*metabolism/*toxicity, Carcinoma, Squamous Cell/*chemically induced/metabolism, Cell Transformation, Neoplastic, Cells, Cultured, Cytochrome P-450 CYP1A1/metabolism, *DNA Damage, Genes, ras, Humans, Keratinocytes/metabolism/pathology, Langerhans Cells/immunology/*metabolism, Mice, Mice, Transgenic, Skin Neoplasms/*chemically induced/metabolism, T-Lymphocytes/immunology

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Dystroglycan function requires xylosyl- and glucuronyltransferase activities of LARGE.

Publication Date: 2012 Jan 6 PMID: 22223806
Authors: Inamori, K. - Yoshida-Moriguchi, T. - Hara, Y. - Anderson, M. E. - Yu, L. - Campbell, K. P.
Journal: Science

Posttranslational modification of alpha-dystroglycan (alpha-DG) by the like-acetylglucosaminyltransferase (LARGE) is required for it to function as an extracellular matrix (ECM) receptor. Mutations in the LARGE gene have been identified in congenital muscular dystrophy patients with brain abnormalities. However, the precise function of LARGE remains unclear. Here we found that LARGE could act as a bifunctional glycosyltransferase, with both xylosyltransferase and glucuronyltransferase activities, which produced repeating units of [-3-xylose-alpha1,3-glucuronic acid-beta1-]. This modification allowed alpha-DG to bind laminin-G domain-containing ECM ligands.

MeSH Categories: Amino Acid Motifs, Animals, CHO Cells, Carbohydrate Conformation, Catalytic Domain, Cricetinae, Dystroglycans/chemistry/*metabolism, Glucuronic Acid/metabolism, Glucuronosyltransferase/metabolism, Glycosaminoglycans/metabolism, Glycosylation, HEK293 Cells, Humans, Laminin/metabolism, Ligands, Mice, Mutation, N-Acetylglucosaminyltransferases/chemistry/genetics/*metabolism, Pentosyltransferases/metabolism, Polysaccharides/*metabolism, Protein Processing, Post-Translational, Recombinant Proteins/metabolism, Xylose/metabolism

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Ancestral developmental potential facilitates parallel evolution in ants.

Publication Date: 2012 Jan 6 PMID: 22223805
Authors: Rajakumar, R. - San Mauro, D. - Dijkstra, M. B. - Huang, M. H. - Wheeler, D. E. - Hiou-Tim, F. - Khila, A. - Cournoyea, M. - Abouheif, E.
Journal: Science

Complex worker caste systems have contributed to the evolutionary success of advanced ant societies; however, little is known about the developmental processes underlying their origin and evolution. We combined hormonal manipulation, gene expression, and phylogenetic analyses with field observations to understand how novel worker subcastes evolve. We uncovered an ancestral developmental potential to produce a "supersoldier" subcaste that has been actualized at least two times independently in the hyperdiverse ant genus Pheidole. This potential has been retained and can be environmentally induced throughout the genus. Therefore, the retention and induction of this potential have facilitated the parallel evolution of supersoldiers through a process known as genetic accommodation. The recurrent induction of ancestral developmental potential may facilitate the adaptive and parallel evolution of phenotypes.

MeSH Categories: Animals, Ants/*genetics/growth & development/physiology, *Biological Evolution, Environment, Female, Genes, Insect, Larva/growth & development, Male, Methoprene/pharmacology, Molecular Sequence Data, Phenotype, Phylogeny, Selection, Genetic, Social Behavior, Wing/growth & development

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Multiyear prediction of monthly mean Atlantic Meridional Overturning Circulation at 26.5 degrees N.

Publication Date: 2012 Jan 6 PMID: 22223804
Authors: Matei, D. - Baehr, J. - Jungclaus, J. H. - Haak, H. - Muller, W. A. - Marotzke, J.
Journal: Science

Attempts to predict changes in Atlantic Meridional Overturning Circulation (AMOC) have yielded little success to date. Here, we demonstrate predictability for monthly mean AMOC strength at 26.5 degrees N for up to 4 years in advance. This AMOC predictive skill arises predominantly from the basin-wide upper-mid-ocean geostrophic transport, which in turn can be predicted because we have skill in predicting the upper-ocean zonal density difference. Ensemble forecasts initialized between January 2008 and January 2011 indicate a stable AMOC at 26.5 degrees N until at least 2014, despite a brief wind-induced weakening in 2010. Because AMOC influences many aspects of climate, our results establish AMOC as an important potential carrier of climate predictability.

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An exhumation history of continents over billion-year time scales.

Publication Date: 2012 Jan 6 PMID: 22223803
Authors: Blackburn, T. J. - Bowring, S. A. - Perron, J. T. - Mahan, K. H. - Dudas, F. O. - Barnhart, K. R.
Journal: Science

The continental lithosphere contains the oldest and most stable structures on Earth, where fragments of ancient material have eluded destruction by tectonic and surface processes operating over billions of years. Although present-day erosion of these remnants is slow, a record of how they have uplifted, eroded, and cooled over Earth's history can provide insight into the physical properties of the continents and the forces operating to exhume them over geologic time. We constructed a continuous record of ancient lithosphere cooling with the use of uranium-lead (U-Pb) thermochronology on volcanically exhumed lower crustal fragments. Combining these measurements with thermal and Pb-diffusion models constrains the range of possible erosion histories. Measured U-Pb data are consistent with extremely low erosion rates persisting over time scales approaching the age of the continents themselves.

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Ohm's law survives to the atomic scale.

Publication Date: 2012 Jan 6 PMID: 22223802
Authors: Weber, B. - Mahapatra, S. - Ryu, H. - Lee, S. - Fuhrer, A. - Reusch, T. C. - Thompson, D. L. - Lee, W. C. - Klimeck, G. - Hollenberg, L. C. - Simmons, M. Y.
Journal: Science

As silicon electronics approaches the atomic scale, interconnects and circuitry become comparable in size to the active device components. Maintaining low electrical resistivity at this scale is challenging because of the presence of con fi ning surfaces and interfaces. We report on the fabrication of wires in silicon--only one atom tall and four atoms wide--with exceptionally low resistivity (~0.3 milliohm-centimeters) and the current-carrying capabilities of copper. By embedding phosphorus atoms within a silicon crystal with an average spacing of less than 1 nanometer, we achieved a diameter-independent resistivity, which demonstrates ohmic scaling to the atomic limit. Atomistic tight-binding calculations con fi rm the metallicity of these atomic-scale wires, which pave the way for single-atom device architectures for both classical and quantum information processing.

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Subparticle ultrafast spectrum imaging in 4D electron microscopy.

Publication Date: 2012 Jan 6 PMID: 22223801
Authors: Yurtsever, A. - van der Veen, R. M. - Zewail, A. H.
Journal: Science

Single-particle imaging of structures has become a powerful methodology in nanoscience and molecular and cell biology. We report the development of subparticle imaging with space, time, and energy resolutions of nanometers, femtoseconds, and millielectron volts, respectively. By using scanning electron probes across optically excited nanoparticles and interfaces, we simultaneously constructed energy-time and space-time maps. Spectrum images were then obtained for the nanoscale dielectric fields, with the energy resolution set by the photon rather than the electron, as demonstrated here with two examples (silver nanoparticles and the metallic copper-vacuum interface). This development thus combines the high spatial resolution of electron microscopy with the high energy resolution of optical techniques and ultrafast temporal response, opening the door to various applications in elemental analysis as well as mapping of interfaces and plasmonics.

MeSH Categories: Copper, Light, Metal Nanoparticles, *Microscopy, Electron/methods, Photons, Silver, Time, Vacuum

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PrP antibodies do not trigger mouse hippocampal neuron apoptosis.

Publication Date: 2012 Jan 6 PMID: 22223800
Authors: Klohn, P. C. - Farmer, M. - Linehan, J. M. - O'Malley, C. - Fernandez de Marco, M. - Taylor, W. - Farrow, M. - Khalili-Shirazi, A. - Brandner, S. - Collinge, J.
Journal: Science

Intraperitoneal administration of ICSM18 and 35, monoclonal antibodies against prion protein (PrP), has been shown to significantly delay the onset of prion disease in mice, and humanized versions are candidate therapeutics for prion and Alzheimer's diseases. However, a previous report of severe and widespread apoptosis after intracerebral injection of anti-PrP monoclonal antibodies raised concerns about such therapy and led to an influential model of prion neurotoxicity via cross-linking of cell surface PrP by disease-related PrP aggregates. In extensive studies including ICSM18 and 35, fully humanized ICSM18, and the previously reported proapoptotic antibodies, we found no evidence of apoptosis, thereby questioning this model of prion neurotoxicity.

MeSH Categories: Animals, Antibodies, Monoclonal/*administration & dosage/immunology, Antibodies, Monoclonal, Humanized/administration & dosage/immunology, *Apoptosis, Epitopes/immunology, Hippocampus/*cytology, Immunoglobulin G/administration & dosage/immunology, Mice, Mice, Inbred C57BL, Neurons/immunology/*physiology, PrPC Proteins/*immunology

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Retrospective. Lloyd J. Old (1933-2011).

Publication Date: 2012 Jan 6 PMID: 22223799
Authors: Sharma, P. - Allison, J. P.
Journal: Science

MeSH Categories: Animals, Cancer Vaccines/history/therapeutic use, History, 20th Century, History, 21st Century, Humans, Mice, Neoplasms/history/*immunology/therapy, United States

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Applied physics. Plasmonic modes revealed.

Publication Date: 2012 Jan 6 PMID: 22223798
Authors: Batson, P. E.
Journal: Science

MeSH Categories: *Microscopy, Electron

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Plant science. Controlling hormone action by subversion and deception.

Publication Date: 2012 Jan 6 PMID: 22223797
Authors: Leung, J.
Journal: Science

MeSH Categories: Abscisic Acid/*metabolism, Arabidopsis/*metabolism, Arabidopsis Proteins/*chemistry/*metabolism, *Molecular Mimicry, Phosphoprotein Phosphatases/*chemistry/*metabolism, Protein-Serine-Threonine Kinases/*chemistry/*metabolism

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Applied physics. Ohm's law in a quantum world.

Publication Date: 2012 Jan 6 PMID: 22223796
Authors: Ferry, D. K.
Journal: Science

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Genetics. Variable outcome of mutations.

Publication Date: 2012 Jan 6 PMID: 22223795
Authors: Deplancke, B. - Verstrepen, K. J.
Journal: Science

MeSH Categories: Animals, Caenorhabditis elegans/*genetics, *Genetic Fitness, *Mutation, *Penetrance, *Stress, Physiological

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Comment on "Nonreciprocal light propagation in a silicon photonic circuit".

Publication Date: 2012 Jan 6 PMID: 22223793
Authors: Fan, S. - Baets, R. - Petrov, A. - Yu, Z. - Joannopoulos, J. D. - Freude, W. - Melloni, A. - Popovic, M. - Vanwolleghem, M. - Jalas, D. - Eich, M. - Krause, M. - Renner, H. - Brinkmeyer, E. - Doerr, C. R.
Journal: Science

We show that the structure demonstrated by Feng et al. (Reports, 5 August 2011, p. 729) cannot enable optical isolation because it possesses a symmetric scattering matrix. Moreover, one cannot construct an optical isolator by incorporating this structure into any system as long as the system is linear and time-independent and is described by materials with a scalar dielectric function.

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Profile: Kit Parker. Engineering a new line of attack on a signature war injury.

Publication Date: 2012 Jan 6 PMID: 22223790
Authors: Miller, G.
Journal: Science

MeSH Categories: Afghan Campaign 2001-, Animals, Axons/pathology, Blast Injuries/pathology/*physiopathology, Brain Injuries/epidemiology/pathology/*physiopathology, Cells, Cultured, History, 21st Century, Humans, Integrins/metabolism, Iraq War, 2003 -, Neurons/physiology, Tissue Engineering, Vasospasm, Intracranial/pathology/physiopathology

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Cancer research. Ravenous for glucose.

Publication Date: 2012 Jan 6 PMID: 22223789
Authors: Taubes, G.
Journal: Science

MeSH Categories: Glucose/*metabolism, *Glycolysis, Humans, Insulin/metabolism, Neoplasms/*metabolism, Signal Transduction, Somatomedins/metabolism

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Cancer research. Cancer prevention with a diabetes pill?

Publication Date: 2012 Jan 6 PMID: 22223788
Authors: Taubes, G.
Journal: Science

MeSH Categories: AMP-Activated Protein Kinases/metabolism, Animals, Anticarcinogenic Agents/*therapeutic use, Blood Glucose/metabolism, Clinical Trials as Topic, Diabetes Mellitus, Type 2/drug therapy, Humans, Hypoglycemic Agents/pharmacology/*therapeutic use, Insulin/blood/metabolism, Metformin/pharmacology/*therapeutic use, Mice, Neoplasms/epidemiology/*prevention & control, Protein-Serine-Threonine Kinases/metabolism, Somatomedins/metabolism

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Cancer research. Unraveling the obesity-cancer connection.

Publication Date: 2012 Jan 6 PMID: 22223787
Authors: Taubes, G.
Journal: Science

MeSH Categories: Animals, Cell Proliferation, Diabetes Mellitus, Type 2/complications/*metabolism, Diet, Glucose/metabolism, Humans, Insulin/blood/*metabolism, Mutation, Neoplasms/*etiology/genetics/metabolism/pathology, Obesity/complications/*metabolism, Phosphatidylinositol 3-Kinases/metabolism, Receptor, Insulin/metabolism, Receptors, Somatomedin/metabolism, Signal Transduction, Somatomedins/*metabolism

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U.S. graduate education. Cornell's plans for the Big Apple rely on quality, cash, and dreams.

Publication Date: 2012 Jan 6 PMID: 22223786
Authors: Kean, S.
Journal: Science

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U.S. science. Research remains a favored child in budget decisions.

Publication Date: 2012 Jan 6 PMID: 22223785
Authors: Mervis, J.
Journal: Science

MeSH Categories: *Budgets/legislation & jurisprudence, Financing, Government, Research/*economics, United States, United States Government Agencies/*economics

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Oceanography. China makes waves with ambitious ocean research plan.

Publication Date: 2012 Jan 6 PMID: 22223784
Authors: Stone, R.
Journal: Science

MeSH Categories: China, Climate, *Geologic Sediments/microbiology, *Oceanography, Oceans and Seas, *Research, Seawater/microbiology

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Energy. Laser fusion project alters goals, fueling concern over its strategy.

Publication Date: 2012 Jan 6 PMID: 22223783
Authors: Clery, D.
Journal: Science

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Biosecurity. In the eye of the storm, two rivals, two strategies.

Publication Date: 2012 Jan 6 PMID: 22223782
Authors: Enserink, M.
Journal: Science

MeSH Categories: History, 21st Century, *Influenza A Virus, H5N1 Subtype, Japan, Netherlands, *Publishing, *Research Personnel, United States

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Biosecurity. Will flu papers lead to new research oversight?

Publication Date: 2012 Jan 6 PMID: 22223781
Authors: Enserink, M. - Malakoff, D.
Journal: Science

MeSH Categories: *Access to Information, Advisory Committees, Animals, Biomedical Research, Bioterrorism/*prevention & control, Humans, Influenza A Virus, H5N1 Subtype/genetics/*pathogenicity, Influenza, Human/transmission, International Cooperation, Orthomyxoviridae Infections/*transmission/virology, *Publishing, *Security Measures, United States, World Health Organization

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Voices of the next generation.

Publication Date: 2012 Jan 6 PMID: 22223776
Authors: Alberts, B.
Journal: Science

MeSH Categories: *Periodicals as Topic/trends, *Science/trends

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Activation-induced B cell fates are selected by intracellular stochastic competition.

Publication Date: 2012 Jan 20 PMID: 22223740
Authors: Duffy, K. R. - Wellard, C. J. - Markham, J. F. - Zhou, J. H. - Holmberg, R. - Hawkins, E. D. - Hasbold, J. - Dowling, M. R. - Hodgkin, P. D.
Journal: Science

In response to stimulation, B lymphocytes pursue a large number of distinct fates important for immune regulation. Whether each cell's fate is determined by external direction, internal stochastic processes, or directed asymmetric division is unknown. Measurement of times to isotype switch, to develop into a plasmablast, and to divide or to die for thousands of cells indicated that each fate is pursued autonomously and stochastically. As a consequence of competition between these processes, censorship of alternative outcomes predicts intricate correlations that are observed in the data. Stochastic competition can explain how the allocation of a proportion of B cells to each cell fate is achieved. The B cell may exemplify how other complex cell differentiation systems are controlled.

MeSH Categories: Animals, B-Lymphocytes/*cytology/*immunology, Cell Death, Cell Differentiation, Cell Division, Female, Immunoglobulin Class Switching, *Lymphocyte Activation, Mice, Models, Immunological, Stochastic Processes

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RNA Editing Underlies Temperature Adaptation in K+ Channels from Polar Octopuses.

Publication Date: 2012 Jan 5 PMID: 22223739
Authors: Garrett, S. - Rosenthal, J. J.
Journal: Science

To operate in the extreme cold, ion channels from psychrophiles must have evolved structural changes to compensate for their thermal environment. A reasonable assumption would be that the underlying adaptations lie within the encoding genes. Here, we show that delayed rectifier K(+) channel genes from an Antarctic and a tropical octopus encode channels that differ at only four positions and display very similar behavior when expressed in Xenopus oocytes. However, the transcribed mRNAs are extensively edited, creating functional diversity. One editing site, which recodes an isoleucine to a valine in the channel's pore, greatly accelerates gating kinetics by destabilizing the open state. This site is extensively edited in both Antarctic and Arctic species, but mostly unedited in tropical species. Thus, A-to-I RNA editing can respond to the physical environment.

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Structural Basis for Sequence-Specific Recognition of DNA by TAL Effectors.

Publication Date: 2012 Jan 5 PMID: 22223738
Authors: Deng, D. - Yan, C. - Pan, X. - Mahfouz, M. - Wang, J. - Zhu, J. K. - Shi, Y. - Yan, N.
Journal: Science

TAL effectors, secreted by phytopathogenic bacteria, recognize host DNA sequences through a central domain of tandem repeats. Each repeat comprises 33 to 35 conserved amino acids and targets a specific base pair using two hypervariable residues (known as RVD) at positions 12 and 13. Here, we report the crystal structures of a 11.5-repeat TAL effector in both DNA-free and DNA-bound states. Each TAL repeat comprises two helices connected by a short RVD-containing loop. The 11.5 repeats form a right-handed, super-helical structure that tracks along the sense strand of DNA duplex, with RVDs contacting the major groove. The 12th residue stabilizes the RVD loop, whereas the 13th residue makes a base-specific contact. Understanding DNA recognition by TAL effectors may facilitate rational design of DNA-binding proteins with biotechnological applications.

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Centrosome loss in the evolution of planarians.

Publication Date: 2012 Jan 27 PMID: 22223737
Authors: Azimzadeh, J. - Wong, M. L. - Downhour, D. M. - Sanchez Alvarado, A. - Marshall, W. F.
Journal: Science

The centrosome, a cytoplasmic organelle formed by cylinder-shaped centrioles surrounded by a microtubule-organizing matrix, is a hallmark of animal cells. The centrosome is conserved and essential for the development of all animal species described so far. Here, we show that planarians, and possibly other flatworms, lack centrosomes. In planarians, centrioles are only assembled in terminally differentiating ciliated cells through the acentriolar pathway to trigger the assembly of cilia. We identified a large set of conserved proteins required for centriole assembly in animals and note centrosome protein families that are missing from the planarian genome. Our study uncovers the molecular architecture and evolution of the animal centrosome and emphasizes the plasticity of animal cell biology and development.

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The Crystal Structure of TAL Effector PthXo1 Bound to Its DNA Target.

Publication Date: 2012 Jan 5 PMID: 22223736
Authors: Mak, A. N. - Bradley, P. - Cernadas, R. A. - Bogdanove, A. J. - Stoddard, B. L.
Journal: Science

DNA recognition by TAL effectors is mediated by tandem repeats, each 33 to 35 residues in length, that specify nucleotides via unique repeat variable diresidues (RVDs). The crystal structure of PthXo1 bound to its DNA target was determined using high-throughput computational structure prediction and validated by heavy-atom derivatization. Each repeat forms a left-handed, two-helix bundle that presents an RVD-containing loop to the DNA. The repeats self-associate to form a right-handed superhelix wrapped around the DNA major groove. The first RVD residue forms a stabilizing contact with the protein backbone, while the second makes a base-specific contact to the DNA sense strand. Two degenerate N-terminal repeats also interact with the DNA. Containing several RVDs and noncanonical associations, the structure illustrates the basis of TAL effector-DNA recognition.

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Broadband light bending with plasmonic nanoantennas.

Publication Date: 2012 Jan 27 PMID: 22194414
Authors: Ni, X. - Emani, N. K. - Kildishev, A. V. - Boltasseva, A. - Shalaev, V. M.
Journal: Science

The precise manipulation of a propagating wave using phase control is a fundamental building block of optical systems. The wavefront of a light beam propagating across an interface can be modified arbitrarily by introducing abrupt phase changes. We experimentally demonstrated unparalleled wavefront control in a broadband optical wavelength range from 1.0 to 1.9 micrometers. This is accomplished by using an extremely thin plasmonic layer (~lambda/50) consisting of an optical nanoantenna array that provides subwavelength phase manipulation on light propagating across the interface. Anomalous light-bending phenomena, including negative angles of refraction and reflection, are observed in the operational wavelength range.

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High-resolution view of the yeast meiotic program revealed by ribosome profiling.

Publication Date: 2012 Feb 3 PMID: 22194413
Authors: Brar, G. A. - Yassour, M. - Friedman, N. - Regev, A. - Ingolia, N. T. - Weissman, J. S.
Journal: Science

Meiosis is a complex developmental process that generates haploid cells from diploid progenitors. We measured messenger RNA (mRNA) abundance and protein production through the yeast meiotic sporulation program and found strong, stage-specific expression for most genes, achieved through control of both mRNA levels and translational efficiency. Monitoring of protein production timing revealed uncharacterized recombination factors and extensive organellar remodeling. Meiotic translation is also shifted toward noncanonical sites, including short open reading frames (ORFs) on unannnotated transcripts and upstream regions of known transcripts (uORFs). Ribosome occupancy at near-cognate uORFs was associated with more efficient ORF translation; by contrast, some AUG uORFs, often exposed by regulated 5' leader extensions, acted competitively. This work reveals pervasive translational control in meiosis and helps to illuminate the molecular basis of the broad restructuring of meiotic cells.

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Widespread genetic switches and toxicity resistance proteins for fluoride.

Publication Date: 2012 Jan 13 PMID: 22194412
Authors: Baker, J. L. - Sudarsan, N. - Weinberg, Z. - Roth, A. - Stockbridge, R. B. - Breaker, R. R.
Journal: Science

Most riboswitches are metabolite-binding RNA structures located in bacterial messenger RNAs where they control gene expression. We have discovered a riboswitch class in many bacterial and archaeal species whose members are selectively triggered by fluoride but reject other small anions, including chloride. These fluoride riboswitches activate expression of genes that encode putative fluoride transporters, enzymes that are known to be inhibited by fluoride, and additional proteins of unknown function. Our findings indicate that most organisms are naturally exposed to toxic levels of fluoride and that many species use fluoride-sensing RNAs to control the expression of proteins that alleviate the deleterious effects of this anion.

MeSH Categories: Anion Transport Proteins/genetics/metabolism, Aptamers, Nucleotide, Bacterial Proteins/*genetics/metabolism, Calcium/metabolism, *Drug Resistance, Bacterial, Escherichia coli/genetics/growth & development/metabolism, Fluorides/metabolism/*pharmacology, *Gene Expression Regulation, Bacterial, Ion Channels/genetics/metabolism, Nucleic Acid Conformation, Pseudomonas syringae/drug effects/*genetics/metabolism, RNA, Bacterial/chemistry/genetics/metabolism, *Riboswitch, Sodium Fluoride/metabolism/pharmacology, Transformation, Bacterial

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Polymerase exchange during Okazaki fragment synthesis observed in living cells.

Publication Date: 2012 Jan 20 PMID: 22194411
Authors: Lia, G. - Michel, B. - Allemand, J. F.
Journal: Science

DNA replication machineries have been studied extensively, but the kinetics of action of their components remains largely unknown. We report a study of DNA synthesis during replication in living Escherichia coli cells. Using single-molecule microscopy, we observed repetitive fluorescence bursts of single polymerase IIIs (Pol IIIs), indicating polymerase exchange at the replication fork. Fluctuations in the amount of DNA-bound single-stranded DNA-binding protein (SSB) reflect different speeds for the leading- and lagging-strand DNA polymerases. Coincidence analyses of Pol III and SSB fluctuations show that they correspond to the lagging-strand synthesis and suggest the use of a new Pol III for each Okazaki fragment. Based on exchanges involving two Pol IIIs, we propose that the third polymerase in the replisome is involved in lagging-strand synthesis.

MeSH Categories: Bacterial Proteins/metabolism, DNA/*biosynthesis, DNA Polymerase III/*metabolism, *DNA Replication, DNA, Bacterial/*biosynthesis, DNA, Single-Stranded/metabolism, DNA-Binding Proteins/*metabolism, Escherichia coli/*metabolism, Escherichia coli Proteins/*metabolism, Fluorescence, Kinetics, Luminescent Proteins/metabolism, Models, Biological, Photobleaching, Recombinant Fusion Proteins/metabolism

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An all-silicon passive optical diode.

Publication Date: 2012 Jan 27 PMID: 22194410
Authors: Fan, L. - Wang, J. - Varghese, L. T. - Shen, H. - Niu, B. - Xuan, Y. - Weiner, A. M. - Qi, M.
Journal: Science

A passive optical diode effect would be useful for on-chip optical information processing but has been difficult to achieve. Using a method based on optical nonlinearity, we demonstrate a forward-backward transmission ratio of up to 28 decibels within telecommunication wavelengths. Our device, which uses two silicon rings 5 micrometers in radius, is passive yet maintains optical nonreciprocity for a broad range of input power levels, and it performs equally well even if the backward input power is higher than the forward input. The silicon optical diode is ultracompact and is compatible with current complementary metal-oxide semiconductor processing.

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The Southern Ocean's role in carbon exchange during the last deglaciation.

Publication Date: 2012 Feb 3 PMID: 22174131
Authors: Burke, A. - Robinson, L. F.
Journal: Science

Changes in the upwelling and degassing of carbon from the Southern Ocean form one of the leading hypotheses for the cause of glacial-interglacial changes in atmospheric carbon dioxide. We present a 25,000-year-long Southern Ocean radiocarbon record reconstructed from deep-sea corals, which shows radiocarbon-depleted waters during the glacial period and through the early deglaciation. This depletion and associated deep stratification disappeared by ~14.6 ka (thousand years ago), consistent with the transfer of carbon from the deep ocean to the surface ocean and atmosphere via a Southern Ocean ventilation event. Given this evidence for carbon exchange in the Southern Ocean, we show that existing deep-ocean radiocarbon records from the glacial period are sufficiently depleted to explain the ~190 per mil drop in atmospheric radiocarbon between ~17 and 14.5 ka.

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Equilibrative nucleoside transporter 3 deficiency perturbs lysosome function and macrophage homeostasis.

Publication Date: 2012 Jan 6 PMID: 22174130
Authors: Hsu, C. L. - Lin, W. - Seshasayee, D. - Chen, Y. H. - Ding, X. - Lin, Z. - Suto, E. - Huang, Z. - Lee, W. P. - Park, H. - Xu, M. - Sun, M. - Rangell, L. - Lutman, J. L. - Ulufatu, S. - Stefanich, E. - Chalouni, C. - Sagolla, M. - Diehl, L. - Fielder, P. - Dean, B. - Balazs, M. - Martin, F.
Journal: Science

Lysosomal storage diseases (LSDs) are a group of heterogeneous disorders caused by defects in lysosomal enzymes or transporters, resulting in accumulation of undegraded macromolecules or metabolites. Macrophage numbers are expanded in several LSDs, leading to histiocytosis of unknown pathophysiology. Here, we found that mice lacking the equilibrative nucleoside transporter 3 (ENT3) developed a spontaneous and progressive macrophage-dominated histiocytosis. In the absence of ENT3, defective apoptotic cell clearance led to lysosomal nucleoside buildup, elevated intralysosomal pH, and altered macrophage function. The macrophage accumulation was partly due to increased macrophage colony-stimulating factor and receptor expression and signaling secondary to the lysosomal defects. These studies suggest a cellular and molecular basis for the development of histiocytosis in several human syndromes associated with ENT3 mutations and potentially other LSDs.

MeSH Categories: Adenosine/metabolism, Animals, Apoptosis, Cell Count, Cell Proliferation, Cells, Cultured, Histiocytosis/*physiopathology, *Homeostasis, Humans, Hydrogen-Ion Concentration, Listeriosis/immunology/microbiology, Lysosomal Storage Diseases/physiopathology, Lysosomes/*physiology/ultrastructure, Macrophage Colony-Stimulating Factor/metabolism, Macrophages/immunology/*physiology/ultrastructure, Mice, Mice, Inbred C57BL, Mice, Knockout, Myelopoiesis, Nucleoside Transport Proteins/genetics/*physiology, Phagocytosis, Receptor, Macrophage Colony-Stimulating Factor/metabolism, Signal Transduction, Thymocytes/immunology/physiology

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Asymmetry and aging of mycobacterial cells lead to variable growth and antibiotic susceptibility.

Publication Date: 2012 Jan 6 PMID: 22174129
Authors: Aldridge, B. B. - Fernandez-Suarez, M. - Heller, D. - Ambravaneswaran, V. - Irimia, D. - Toner, M. - Fortune, S. M.
Journal: Science

Cells use both deterministic and stochastic mechanisms to generate cell-to-cell heterogeneity, which enables the population to better withstand environmental stress. Here we show that, within a clonal population of mycobacteria, there is deterministic heterogeneity in elongation rate that arises because mycobacteria grow in an unusual, unipolar fashion. Division of the asymmetrically growing mother cell gives rise to daughter cells that differ in elongation rate and size. Because the mycobacterial cell division cycle is governed by time, not cell size, rapidly elongating cells do not divide more frequently than slowly elongating cells. The physiologically distinct subpopulations of cells that arise through asymmetric growth and division are differentially susceptible to clinically important classes of antibiotics.

MeSH Categories: Anti-Bacterial Agents/*pharmacology, Cell Cycle, Cell Division, Cell Wall/metabolism, Cycloserine/pharmacology, Escherichia coli/cytology/growth & development, Isoniazid/pharmacology, Microbial Sensitivity Tests, Microfluidic Analytical Techniques, Mycobacterium smegmatis/cytology/*drug effects/*growth &, development/metabolism, Mycobacterium tuberculosis/cytology/*drug effects/*growth &, development/metabolism, Rifampin/pharmacology, Thienamycins/pharmacology, Time Factors

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Asymmetric B cell division in the germinal center reaction.

Publication Date: 2012 Jan 20 PMID: 22174128
Authors: Barnett, B. E. - Ciocca, M. L. - Goenka, R. - Barnett, L. G. - Wu, J. - Laufer, T. M. - Burkhardt, J. K. - Cancro, M. P. - Reiner, S. L.
Journal: Science

Lifelong antibody responses to vaccination require reorganization of lymphoid tissue and dynamic intercellular communication called the germinal center reaction. B lymphocytes undergo cellular polarization during antigen stimulation, acquisition, and presentation, which are critical steps for initiating humoral immunity. Here, we show that germinal center B lymphocytes asymmetrically segregate the transcriptional regulator Bcl6, the receptor for interleukin-21, and the ancestral polarity protein atypical protein kinase C to one side of the plane of division, generating unequal inheritance of fate-altering molecules by daughter cells. Germinal center B lymphocytes from mice with a defect in leukocyte adhesion fail to divide asymmetrically. These results suggest that motile cells lacking constitutive attachment can receive provisional polarity cues from the microenvironment to generate daughter cell diversity and self-renewal.

MeSH Categories: Animals, Antigens, CD40/metabolism, *Asymmetric Cell Division, B-Lymphocytes/*cytology/*immunology/metabolism, Cell Adhesion, Cell Communication, Cell Polarity, Cellular Microenvironment, Cues, DNA-Binding Proteins/metabolism, Germinal Center/*cytology/*immunology, Immunization, Mice, Mice, Inbred C57BL, Mitosis, Protein Kinase C/metabolism, Receptors, Interleukin-21/metabolism

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Research agenda. Guiding limited use of chimpanzees in research.

Publication Date: 2012 Jan 6 PMID: 22174127
Authors: Altevogt, B. M. - Pankevich, D. E. - Pope, A. M. - Kahn, J. P.
Journal: Science

MeSH Categories: Advisory Committees, *Animal Experimentation/legislation & jurisprudence, Animals, *Biomedical Research/legislation & jurisprudence, Guidelines as Topic, Institute of Medicine (U.S.), National Academy of Sciences (U.S.), *Pan troglodytes, United States

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Fitness trade-offs and environmentally induced mutation buffering in isogenic C. elegans.

Publication Date: 2012 Jan 6 PMID: 22174126
Authors: Casanueva, M. O. - Burga, A. - Lehner, B.
Journal: Science

Mutations often have consequences that vary across individuals. Here, we show that the stimulation of a stress response can reduce mutation penetrance in Caenorhabditis elegans. Moreover, this induced mutation buffering varies across isogenic individuals because of interindividual differences in stress signaling. This variation has important consequences in wild-type animals, producing some individuals with higher stress resistance but lower reproductive fitness and other individuals with lower stress resistance and higher reproductive fitness. This may be beneficial in an unpredictable environment, acting as a "bet-hedging" strategy to diversify risk. These results illustrate how transient environmental stimuli can induce protection against mutations, how environmental responses can underlie variable mutation buffering, and how a fitness trade-off may make variation in stress signaling advantageous.

MeSH Categories: Animals, Animals, Genetically Modified, Caenorhabditis elegans/*genetics/growth & development/physiology, Caenorhabditis elegans Proteins/genetics/metabolism, Cell Nucleus/metabolism, Environment, *Genetic Fitness, HSP90 Heat-Shock Proteins/genetics/metabolism, Heat-Shock Proteins/genetics/metabolism, *Mutation, *Penetrance, Phenotype, Recombinant Fusion Proteins/metabolism, Signal Transduction, *Stress, Physiological, Transcription Factors/genetics/metabolism

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Sucrose efflux mediated by SWEET proteins as a key step for phloem transport.

Publication Date: 2012 Jan 13 PMID: 22157085
Authors: Chen, L. Q. - Qu, X. Q. - Hou, B. H. - Sosso, D. - Osorio, S. - Fernie, A. R. - Frommer, W. B.
Journal: Science

Plants transport fixed carbon predominantly as sucrose, which is produced in mesophyll cells and imported into phloem cells for translocation throughout the plant. It is not known how sucrose migrates from sites of synthesis in the mesophyll to the phloem, or which cells mediate efflux into the apoplasm as a prerequisite for phloem loading by the SUT sucrose-H(+) (proton) cotransporters. Using optical sucrose sensors, we identified a subfamily of SWEET sucrose efflux transporters. AtSWEET11 and 12 localize to the plasma membrane of the phloem. Mutant plants carrying insertions in AtSWEET11 and 12 are defective in phloem loading, thus revealing a two-step mechanism of SWEET-mediated export from parenchyma cells feeding H(+)-coupled import into the sieve element-companion cell complex. We discuss how restriction of intercellular transport to the interface of adjacent phloem cells may be an effective mechanism to limit the availability of photosynthetic carbon in the leaf apoplasm in order to prevent pathogen infections.

MeSH Categories: Animals, Arabidopsis/genetics/growth & development/*metabolism, Arabidopsis Proteins/genetics/*metabolism, Biological Transport, Cell Membrane/metabolism, Fluorescence Resonance Energy Transfer, HEK293 Cells, Humans, Membrane Transport Proteins/genetics/*metabolism, Mutant Proteins/metabolism, Oryza sativa/metabolism, Phloem/*metabolism, Plant Leaves/metabolism, Plant Proteins/genetics/metabolism, Plant Roots/growth & development, Promoter Regions, Genetic, Sucrose/*metabolism

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Behavior. How honeybees break a decision-making deadlock.

Publication Date: 2012 Jan 6 PMID: 22157084
Authors: Niven, J. E.
Journal: Science

MeSH Categories: *Animal Communication, Animals, Bees/*physiology, *Nesting Behavior

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Cytoplasmic dynein moves through uncoordinated stepping of the AAA+ ring domains.

Publication Date: 2012 Jan 13 PMID: 22157083
Authors: DeWitt, M. A. - Chang, A. Y. - Combs, P. A. - Yildiz, A.
Journal: Science

Cytoplasmic dynein is a homodimeric AAA+ motor that transports a multitude of cargos toward the microtubule minus end. How the two catalytic head domains interact and move relative to each other during processive movement is unclear. Here, we tracked the relative positions of both heads with nanometer precision and directly observed the heads moving independently along the microtubule. The heads remained widely separated, and their stepping behavior varied as a function of interhead separation. One active head was sufficient for processive movement, and an active head could drag an inactive partner head forward. Thus, dynein moves processively without interhead coordination, a mechanism fundamentally distinct from the hand-over-hand stepping of kinesin and myosin.

MeSH Categories: Adenosine Triphosphate/metabolism, Cytoplasm/*metabolism, Dyneins/*chemistry/*metabolism, Microtubules/*metabolism, Models, Biological, Models, Molecular, Protein Multimerization, Protein Structure, Tertiary, Recombinant Fusion Proteins/chemistry/metabolism, Saccharomyces cerevisiae Proteins/*chemistry/*metabolism

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Synthetic partial waves in ultracold atomic collisions.

Publication Date: 2012 Jan 20 PMID: 22157082
Authors: Williams, R. A. - LeBlanc, L. J. - Jimenez-Garcia, K. - Beeler, M. C. - Perry, A. R. - Phillips, W. D. - Spielman, I. B.
Journal: Science

Interactions between particles can be strongly altered by their environment. We demonstrate a technique for modifying interactions between ultracold atoms by dressing the bare atomic states with light, creating an effective interaction of vastly increased range that scatters states of finite relative angular momentum at collision energies where only s-wave scattering would normally be expected. We collided two optically dressed neutral atomic Bose-Einstein condensates with equal, and opposite, momenta and observed that the usual s-wave distribution of scattered atoms was altered by the appearance of d- and g-wave contributions. This technique is expected to enable quantum simulation of exotic systems, including those predicted to support Majorana fermions.

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Stop signals provide cross inhibition in collective decision-making by honeybee swarms.

Publication Date: 2012 Jan 6 PMID: 22157081
Authors: Seeley, T. D. - Visscher, P. K. - Schlegel, T. - Hogan, P. M. - Franks, N. R. - Marshall, J. A.
Journal: Science

Honeybee swarms and complex brains show many parallels in how they make decisions. In both, separate populations of units (bees or neurons) integrate noisy evidence for alternatives, and, when one population exceeds a threshold, the alternative it represents is chosen. We show that a key feature of a brain--cross inhibition between the evidence-accumulating populations--also exists in a swarm as it chooses its nesting site. Nest-site scouts send inhibitory stop signals to other scouts producing waggle dances, causing them to cease dancing, and each scout targets scouts' reporting sites other than her own. An analytic model shows that cross inhibition between populations of scout bees increases the reliability of swarm decision-making by solving the problem of deadlock over equal sites.

MeSH Categories: *Animal Communication, Animals, Bees/*physiology, Behavior, Animal, Decision Making, Models, Biological, Models, Neurological, Movement, *Nesting Behavior, Neural Inhibition, Neurons/physiology, Social Behavior

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Capturing ultrasmall EMT zeolite from template-free systems.

Publication Date: 2012 Jan 6 PMID: 22157080
Authors: Ng, E. P. - Chateigner, D. - Bein, T. - Valtchev, V. - Mintova, S.
Journal: Science

Small differences between the lattice energies of different zeolites suggest that kinetic factors are of major importance in controlling zeolite nucleation. Thus, it is critical to control the nucleation kinetics in order to obtain a desired microporous material. Here, we demonstrate how careful investigation of the very early stages of zeolite crystallization in colloidal systems can provide access to important nanoscale zeolite phases while avoiding the use of expensive organic templates. We report the effective synthesis of ultrasmall (6- to 15-nanometer) crystals of the large-pore zeolite EMT from template-free colloidal precursors at low temperature (30 degrees C) and very high yield.

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A SUMOylation-dependent transcriptional subprogram is required for Myc-driven tumorigenesis.

Publication Date: 2012 Jan 20 PMID: 22157079
Authors: Kessler, J. D. - Kahle, K. T. - Sun, T. - Meerbrey, K. L. - Schlabach, M. R. - Schmitt, E. M. - Skinner, S. O. - Xu, Q. - Li, M. Z. - Hartman, Z. C. - Rao, M. - Yu, P. - Dominguez-Vidana, R. - Liang, A. C. - Solimini, N. L. - Bernardi, R. J. - Yu, B. - Hsu, T. - Golding, I. - Luo, J. - Osborne, C. K. - Creighton, C. J. - Hilsenbeck, S. G. - Schiff, R. - Shaw, C. A. - Elledge, S. J. - Westbrook, T. F.
Journal: Science

Myc is an oncogenic transcription factor frequently dysregulated in human cancer. To identify pathways supporting the Myc oncogenic program, we used a genome-wide RNA interference screen to search for Myc-synthetic lethal genes and uncovered a role for the SUMO-activating enzyme (SAE1/2). Loss of SAE1/2 enzymatic activity drives synthetic lethality with Myc. Inactivation of SAE2 leads to mitotic catastrophe and cell death upon Myc hyperactivation. Mechanistically, SAE2 inhibition switches a transcriptional subprogram of Myc from activated to repressed. A subset of these SUMOylation-dependent Myc switchers (SMS genes) is required for mitotic spindle function and to support the Myc oncogenic program. SAE2 is required for growth of Myc-dependent tumors in mice, and gene expression analyses of Myc-high human breast cancers suggest that low SAE1 and SAE2 abundance in the tumors correlates with longer metastasis-free survival of the patients. Thus, inhibition of SUMOylation may merit investigation as a possible therapy for Myc-driven human cancers.

MeSH Categories: Animals, Breast Neoplasms/*genetics/metabolism/mortality/pathology, Cell Cycle, Cell Line, Tumor, *Cell Transformation, Neoplastic, Female, Gene Expression Profiling, Gene Expression Regulation, Neoplastic, *Genes, myc, Humans, Mammary Neoplasms, Experimental/genetics/metabolism/mortality/pathology, Mice, Mice, Nude, Mitosis, Mitotic Spindle Apparatus/physiology, Neoplasm Transplantation, Proto-Oncogene Proteins c-myc/*metabolism, RNA Interference, RNA, Small Interfering, Sumoylation, *Transcription, Genetic, Transplantation, Heterologous, Ubiquitin-Activating Enzymes/antagonists & inhibitors/*genetics/metabolism

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Candle soot as a template for a transparent robust superamphiphobic coating.

Publication Date: 2012 Jan 6 PMID: 22144464
Authors: Deng, X. - Mammen, L. - Butt, H. J. - Vollmer, D.
Journal: Science

Coating is an essential step in adjusting the surface properties of materials. Superhydrophobic coatings with contact angles greater than 150 degrees and roll-off angles below 10 degrees for water have been developed, based on low-energy surfaces and roughness on the nano- and micrometer scales. However, these surfaces are still wetted by organic liquids such as surfactant-based solutions, alcohols, or alkanes. Coatings that are simultaneously superhydrophobic and superoleophobic are rare. We designed an easily fabricated, transparent, and oil-rebounding superamphiphobic coating. A porous deposit of candle soot was coated with a 25-nanometer-thick silica shell. The black coating became transparent after calcination at 600 degrees C. After silanization, the coating was superamphiphobic and remained so even after its top layer was damaged by sand impingement.

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RNA elimination machinery targeting meiotic mRNAs promotes facultative heterochromatin formation.

Publication Date: 2012 Jan 6 PMID: 22144463
Authors: Zofall, M. - Yamanaka, S. - Reyes-Turcu, F. E. - Zhang, K. - Rubin, C. - Grewal, S. I.
Journal: Science

Facultative heterochromatin that changes during cellular differentiation coordinates regulated gene expression, but its assembly is poorly understood. Here, we describe facultative heterochromatin islands in fission yeast and show that their formation at meiotic genes requires factors that eliminate meiotic messenger RNAs (mRNAs) during vegetative growth. Blocking production of meiotic mRNA or loss of RNA elimination factors, including Mmi1 and Red1 proteins, abolishes heterochromatin islands. RNA elimination machinery is enriched at meiotic loci and interacts with Clr4/SUV39h, a methyltransferase involved in heterochromatin assembly. Heterochromatin islands disassemble in response to nutritional signals that induce sexual differentiation. This process involves the antisilencing factor Epe1, the loss of which causes dramatic increase in heterochromatic loci. Our analyses uncover unexpected regulatory roles for mRNA-processing factors that assemble dynamic heterochromatin to modulate gene expression.

MeSH Categories: Cell Cycle Proteins/metabolism, *Chromatin Assembly and Disassembly, Chromatin Immunoprecipitation, Gene Expression Regulation, Fungal, Genes, Fungal, Heterochromatin/*metabolism, Histones/metabolism, Meiosis/*genetics, Methyltransferases/metabolism, Microtubule Proteins/genetics/metabolism, Nitrogen/metabolism, Nuclear Proteins/genetics/metabolism, RNA Interference, RNA, Fungal/genetics/*metabolism, RNA, Messenger/genetics/*metabolism, Schizosaccharomyces/genetics/growth & development/*metabolism, Schizosaccharomyces pombe Proteins/genetics/*metabolism, mRNA Cleavage and Polyadenylation Factors/metabolism

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The technology path to deep greenhouse gas emissions cuts by 2050: the pivotal role of electricity.

Publication Date: 2012 Jan 6 PMID: 22116030
Authors: Williams, J. H. - DeBenedictis, A. - Ghanadan, R. - Mahone, A. - Moore, J. - Morrow, W. R. 3rd - Price, S. - Torn, M. S.
Journal: Science

Several states and countries have adopted targets for deep reductions in greenhouse gas emissions by 2050, but there has been little physically realistic modeling of the energy and economic transformations required. We analyzed the infrastructure and technology path required to meet California's goal of an 80% reduction below 1990 levels, using detailed modeling of infrastructure stocks, resource constraints, and electricity system operability. We found that technically feasible levels of energy efficiency and decarbonized energy supply alone are not sufficient; widespread electrification of transportation and other sectors is required. Decarbonized electricity would become the dominant form of energy supply, posing challenges and opportunities for economic growth and climate policy. This transformation demands technologies that are not yet commercialized, as well as coordination of investment, technology development, and infrastructure deployment.

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Molecular mimicry regulates ABA signaling by SnRK2 kinases and PP2C phosphatases.

Publication Date: 2012 Jan 6 PMID: 22116026
Authors: Soon, F. F. - Ng, L. M. - Zhou, X. E. - West, G. M. - Kovach, A. - Tan, M. H. - Suino-Powell, K. M. - He, Y. - Xu, Y. - Chalmers, M. J. - Brunzelle, J. S. - Zhang, H. - Yang, H. - Jiang, H. - Li, J. - Yong, E. L. - Cutler, S. - Zhu, J. K. - Griffin, P. R. - Melcher, K. - Xu, H. E.
Journal: Science

Abscisic acid (ABA) is an essential hormone for plants to survive environmental stresses. At the center of the ABA signaling network is a subfamily of type 2C protein phosphatases (PP2Cs), which form exclusive interactions with ABA receptors and subfamily 2 Snfl-related kinase (SnRK2s). Here, we report a SnRK2-PP2C complex structure, which reveals marked similarity in PP2C recognition by SnRK2 and ABA receptors. In the complex, the kinase activation loop docks into the active site of PP2C, while the conserved ABA-sensing tryptophan of PP2C inserts into the kinase catalytic cleft, thus mimicking receptor-PP2C interactions. These structural results provide a simple mechanism that directly couples ABA binding to SnRK2 kinase activation and highlight a new paradigm of kinase-phosphatase regulation through mutual packing of their catalytic sites.

MeSH Categories: Abscisic Acid/chemistry/*metabolism, Amino Acid Sequence, Arabidopsis/chemistry/*metabolism, Arabidopsis Proteins/antagonists & inhibitors/*chemistry/*metabolism, Catalytic Domain, Crystallography, X-Ray, Enzyme Activation, Models, Molecular, *Molecular Mimicry, Molecular Sequence Data, Phosphoprotein Phosphatases/*chemistry/*metabolism, Phosphorylation, Protein Binding, Protein Structure, Tertiary, Protein-Serine-Threonine Kinases/antagonists &, inhibitors/*chemistry/*metabolism, Recombinant Fusion Proteins/chemistry/metabolism, Signal Transduction

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