Science

Science podcast.

Publication Date: 2010 Feb 5 PMID: 20133575
Authors:
Journal: Science

post to: CiteULike

Optimal localization by pointing off axis.

Publication Date: 2010 Feb 5 PMID: 20133574
Authors: Yovel, Y. - Falk, B. - Moss, C. F. - Ulanovsky, N.
Journal: Science

Is centering a stimulus in the field of view an optimal strategy to localize and track it? We demonstrated, through experimental and computational studies, that the answer is no. We trained echolocating Egyptian fruit bats to localize a target in complete darkness, and we measured the directional aim of their sonar clicks. The bats did not center the sonar beam on the target, but instead pointed it off axis, accurately directing the maximum slope ("edge") of the beam onto the target. Information-theoretic calculations showed that using the maximum slope is optimal for localizing the target, at the cost of detection. We propose that the tradeoff between detection (optimized at stimulus peak) and localization (optimized at maximum slope) is fundamental to spatial localization and tracking accomplished through hearing, olfaction, and vision.

post to: CiteULike

Abundance of ribosomal RNA gene copies maintains genome integrity.

Publication Date: 2010 Feb 5 PMID: 20133573
Authors: Ide, S. - Miyazaki, T. - Maki, H. - Kobayashi, T.
Journal: Science

The ribosomal RNA (rDNA) gene repeats are essential housekeeping genes found in all organisms. A gene amplification system maintains large cluster(s) of tandemly repeated copies in the chromosome, with each species having a specific number of copies. Yeast has many untranscribed rDNA copies (extra copies), and we found that when they are lost, the cells become sensitive to DNA damage induced by mutagens. We show that this sensitivity is dependent on rDNA transcriptional activity, which interferes with cohesion between rDNA loci of sister chromatids. The extra rDNA copies facilitate condensin association and sister-chromatid cohesion, thereby facilitating recombinational repair. These results suggest that high concentrations of heavily transcribed genes are toxic to the cells, and therefore amplified genes, such as rDNA, have evolved.

post to: CiteULike

Cryo-EM Model of the Bullet-Shaped Vesicular Stomatitis Virus.

Publication Date: 2010 Feb 5 PMID: 20133572
Authors: Ge, P. - Tsao, J. - Schein, S. - Green, T. J. - Luo, M. - Zhou, Z. H.
Journal: Science

Vesicular stomatitis virus (VSV) is a bullet-shaped rhabdovirus and a model system of negative-strand RNA viruses. Through direct visualization by means of cryo-electron microscopy, we show that each virion contains two nested, left-handed helices: an outer helix of matrix protein M and an inner helix of nucleoprotein N and RNA. M has a hub domain with four contact sites that link to neighboring M and N subunits, providing rigidity by clamping adjacent turns of the nucleocapsid. Side-by-side interactions between neighboring N subunits are critical for the nucleocapsid to form a bullet shape, and structure-based mutagenesis results support this description. Together, our data suggest a mechanism of VSV assembly in which the nucleocapsid spirals from the tip to become the helical trunk, both subsequently framed and rigidified by the M layer.

post to: CiteULike

Conformational spread as a mechanism for cooperativity in the bacterial flagellar switch.

Publication Date: 2010 Feb 5 PMID: 20133571
Authors: Bai, F. - Branch, R. W. - Nicolau, D. V. Jr - Pilizota, T. - Steel, B. C. - Maini, P. K. - Berry, R. M.
Journal: Science

The bacterial flagellar switch that controls the direction of flagellar rotation during chemotaxis has a highly cooperative response. This has previously been understood in terms of the classic two-state, concerted model of allosteric regulation. Here, we used high-resolution optical microscopy to observe switching of single motors and uncover the stochastic multistate nature of the switch. Our observations are in detailed quantitative agreement with a recent general model of allosteric cooperativity that exhibits conformational spread-the stochastic growth and shrinkage of domains of adjacent subunits sharing a particular conformational state. We expect that conformational spread will be important in explaining cooperativity in other large signaling complexes.

post to: CiteULike

Flight orientation behaviors promote optimal migration trajectories in high-flying insects.

Publication Date: 2010 Feb 5 PMID: 20133570
Authors: Chapman, J. W. - Nesbit, R. L. - Burgin, L. E. - Reynolds, D. R. - Smith, A. D. - Middleton, D. R. - Hill, J. K.
Journal: Science

Many insects undertake long-range seasonal migrations to exploit temporary breeding sites hundreds or thousands of kilometers apart, but the behavioral adaptations that facilitate these movements remain largely unknown. Using entomological radar, we showed that the ability to select seasonally favorable, high-altitude winds is widespread in large day- and night-flying migrants and that insects adopt optimal flight headings that partially correct for crosswind drift, thus maximizing distances traveled. Trajectory analyses show that these behaviors increase migration distances by 40% and decrease the degree of drift from seasonally optimal directions. These flight behaviors match the sophistication of those seen in migrant birds and help explain how high-flying insects migrate successfully between seasonal habitats.

post to: CiteULike

Gradual adaptation toward a range-expansion phenotype initiated the global radiation of toads.

Publication Date: 2010 Feb 5 PMID: 20133569
Authors: Van Bocxlaer, I. - Loader, S. P. - Roelants, K. - Biju, S. D. - Menegon, M. - Bossuyt, F.
Journal: Science

Recent studies have identified range expansion as a potential driver of speciation. Yet it remains poorly understood how, under identical extrinsic settings, differential tendencies for geographic movement of taxa originate and subsequently affect diversification. We identified multiple traits that predict large distributional ranges in extant species of toads (Bufonidae) and used statistical methods to define and phylogenetically reconstruct an optimal range-expansion phenotype. Our results indicate that lineage-specific range-shifting abilities increased through an accumulation of adaptive traits that culminated in such a phenotype. This initiated the episode of global colonization and triggered the major radiation of toads. Evolution toward a range-expansion phenotype might be crucial to understanding both ancient widespread radiations and the evolutionary background of contemporary invasive species such as the cane toad.

post to: CiteULike

Water freezes differently on positively and negatively charged surfaces of pyroelectric materials.

Publication Date: 2010 Feb 5 PMID: 20133568
Authors: Ehre, D. - Lavert, E. - Lahav, M. - Lubomirsky, I.
Journal: Science

Although ice melts and water freezes under equilibrium conditions at 0 degrees C, water can be supercooled under homogeneous conditions in a clean environment down to -40 degrees C without freezing. The influence of the electric field on the freezing temperature of supercooled water (electrofreezing) is of topical importance in the living and inanimate worlds. We report that positively charged surfaces of pyroelectric LiTaO(3) crystals and SrTiO(3) thin films promote ice nucleation, whereas the same surfaces when negatively charged reduce the freezing temperature. Accordingly, droplets of water cooled down on a negatively charged LiTaO(3) surface and remaining liquid at -11 degrees C freeze immediately when this surface is heated to -8 degrees C, as a result of the replacement of the negative surface charge by a positive one. Furthermore, powder x-ray diffraction studies demonstrated that the freezing on the positively charged surface starts at the solid/water interface, whereas on a negatively charged surface, ice nucleation starts at the air/water interface.

post to: CiteULike

A coherent beam splitter for electronic spin States.

Publication Date: 2010 Feb 5 PMID: 20133567
Authors: Petta, J. R. - Lu, H. - Gossard, A. C.
Journal: Science

Rapid coherent control of electron spin states is required for implementation of a spin-based quantum processor. We demonstrated coherent control of electronic spin states in a double quantum dot by sweeping an initially prepared spin-singlet state through a singlet-triplet anticrossing in the energy-level spectrum. The anticrossing serves as a beam splitter for the incoming spin-singlet state. When performed within the spin-dephasing time, consecutive crossings through the beam splitter result in coherent quantum oscillations between the singlet state and a triplet state. The all-electrical method for quantum control relies on electron-nuclear spin coupling and drives single-electron spin rotations on nanosecond time scales.

post to: CiteULike

Visualizing Critical Correlations Near the Metal-Insulator Transition in Ga1-xMnxAs.

Publication Date: 2010 Feb 5 PMID: 20133566
Authors: Richardella, A. - Roushan, P. - Mack, S. - Zhou, B. - Huse, D. A. - Awschalom, D. D. - Yazdani, A.
Journal: Science

Electronic states in disordered conductors on the verge of localization are predicted to exhibit critical spatial characteristics indicative of the proximity to a metal-insulator phase transition. We used scanning tunneling microscopy to visualize electronic states in Ga(1-)(x)Mn(x)As samples close to this transition. Our measurements show that doping-induced disorder produces strong spatial variations in the local tunneling conductance across a wide range of energies. Near the Fermi energy, where spectroscopic signatures of electron-electron interaction are the most prominent, the electronic states exhibit a diverging spatial correlation length. Power-law decay of the spatial correlations is accompanied by log-normal distributions of the local density of states and multifractal spatial characteristics.

post to: CiteULike

100-GHz Transistors from Wafer-Scale Epitaxial Graphene.

Publication Date: 2010 Feb 5 PMID: 20133565
Authors: Lin, Y. M. - Dimitrakopoulos, C. - Jenkins, K. A. - Farmer, D. B. - Chiu, H. Y. - Grill, A. - Avouris, P.
Journal: Science

The high carrier mobility of graphene has been exploited in field-effect transistors that operate at high frequencies. Transistors were fabricated on epitaxial graphene synthesized on the silicon face of a silicon carbide wafer, achieving a cutoff frequency of 100 gigahertz for a gate length of 240 nanometers. The high-frequency performance of these epitaxial graphene transistors exceeds that of state-of-the-art silicon transistors of the same gate length.

post to: CiteULike

Development of monocytes, macrophages, and dendritic cells.

Publication Date: 2010 Feb 5 PMID: 20133564
Authors: Geissmann, F. - Manz, M. G. - Jung, S. - Sieweke, M. H. - Merad, M. - Ley, K.
Journal: Science

Monocytes and macrophages are critical effectors and regulators of inflammation and the innate immune response, the immediate arm of the immune system. Dendritic cells initiate and regulate the highly pathogen-specific adaptive immune responses and are central to the development of immunologic memory and tolerance. Recent in vivo experimental approaches in the mouse have unveiled new aspects of the developmental and lineage relationships among these cell populations. Despite this, the origin and differentiation cues for many tissue macrophages, monocytes, and dendritic cell subsets in mice, and the corresponding cell populations in humans, remain to be elucidated.

post to: CiteULike

Iron and the carbon pump.

Publication Date: 2010 Feb 5 PMID: 20133563
Authors: Sunda, W. G.
Journal: Science

post to: CiteULike

An ensemble view of allostery.

Publication Date: 2010 Feb 5 PMID: 20133562
Authors: Hilser, V. J.
Journal: Science

post to: CiteULike

Seeing quantum fractals.

Publication Date: 2010 Feb 5 PMID: 20133561
Authors: Fiete, G. A. - de Lozanne, A.
Journal: Science

post to: CiteULike

Splitting spin States on a chip.

Publication Date: 2010 Feb 5 PMID: 20133560
Authors: Burkard, G.
Journal: Science

post to: CiteULike

Tinkering inside the organelle.

Publication Date: 2010 Feb 5 PMID: 20133559
Authors: Alcock, F. - Clements, A. - Webb, C. - Lithgow, T.
Journal: Science

post to: CiteULike

Gene doping and sport.

Publication Date: 2010 Feb 5 PMID: 20133558
Authors: Friedmann, T. - Rabin, O. - Frankel, M. S.
Journal: Science

post to: CiteULike

Taking our lumps--response.

Publication Date: 2010 Feb 5 PMID: 20133557
Authors: Endersby, J.
Journal: Science

post to: CiteULike

Comment on "unexpected epoxide formation in the gas-phase photooxidation of isoprene".

Publication Date: 2010 Feb 5 PMID: 20133556
Authors: Claeys, M.
Journal: Science

Paulot et al. (Reports, 7 August 2009, p. 730) reported that the photooxidation of isoprene under low-nitrogen oxides (NO(x)) conditions produces epoxides that can facilitate the formation of secondary organic aerosol (SOA). However, another pathway involving the formation of methyl-butenediol intermediates can also lead to isoprene-derived SOA formation. Further research is needed to clarify the fate of isoprene in the atmosphere.

post to: CiteULike

Taking our lumps.

Publication Date: 2010 Feb 5 PMID: 20133555
Authors: Wheeler, Q.
Journal: Science

post to: CiteULike

Predators could help save pollock.

Publication Date: 2010 Feb 5 PMID: 20133554
Authors: Wright, B.
Journal: Science

post to: CiteULike

Religiosity tied to socioeconomic status.

Publication Date: 2010 Feb 5 PMID: 20133553
Authors: Paul, G. S.
Journal: Science

post to: CiteULike

Savannas need protection.

Publication Date: 2010 Feb 5 PMID: 20133552
Authors: Lehmann, C. E.
Journal: Science

post to: CiteULike

Greening haiti, tree by tree.

Publication Date: 2010 Feb 5 PMID: 20133551
Authors: Gibbons, A.
Journal: Science

post to: CiteULike

From the bottom up.

Publication Date: 2010 Feb 5 PMID: 20133550
Authors: Kean, S.
Journal: Science

post to: CiteULike

The long battle against a horrific disease.

Publication Date: 2010 Feb 5 PMID: 20133549
Authors: Roberts, L.
Journal: Science

post to: CiteULike

Relief among the rubble.

Publication Date: 2010 Feb 5 PMID: 20133548
Authors: Roberts, L.
Journal: Science

post to: CiteULike

'Toadness' a key feature for global spread of these amphibians.

Publication Date: 2010 Feb 5 PMID: 20133547
Authors: Pennisi, E.
Journal: Science

post to: CiteULike

From Science's Online Daily News Site.

Publication Date: 2010 Feb 5 PMID: 20133546
Authors:
Journal: Science

post to: CiteULike

Big Battle Brewing Over Elephants at Upcoming CITES Meeting.

Publication Date: 2010 Feb 5 PMID: 20133545
Authors: Stokstad, E.
Journal: Science

post to: CiteULike

Publications and Expats Warn Of Russia's Dangerous Decline.

Publication Date: 2010 Feb 5 PMID: 20133544
Authors: Clery, D.
Journal: Science

post to: CiteULike

From the science policy blog.

Publication Date: 2010 Feb 5 PMID: 20133543
Authors:
Journal: Science

post to: CiteULike

New korean science city caught in political crossfire.

Publication Date: 2010 Feb 5 PMID: 20133542
Authors: Normile, D.
Journal: Science

post to: CiteULike

Obama shakes up satellite programs for clearer picture of Earth.

Publication Date: 2010 Feb 5 PMID: 20133541
Authors: Kintisch, E.
Journal: Science

post to: CiteULike

Science Spared From Domestic Spending Freeze--for Now.

Publication Date: 2010 Feb 5 PMID: 20133540
Authors: Mervis, J.
Journal: Science

post to: CiteULike

Ensuring integrity in science.

Publication Date: 2010 Feb 5 PMID: 20133539
Authors: Cicerone, R. J.
Journal: Science

post to: CiteULike

Retromer Is Required for Apoptotic Cell Clearance by Phagocytic Receptor Recycling.

Publication Date: 2010 Feb 4 PMID: 20133524
Authors: Chen, D. - Xiao, H. - Zhang, K. - Wang, B. - Gao, Z. - Jian, Y. - Qi, X. - Sun, J. - Miao, L. - Yang, C.
Journal: Science

The cell surface receptor CED-1 mediates apoptotic cell recognition by phagocytic cells, enabling cell corpse clearance in Caenorhabditis elegans. Here, we found that the C. elegans intracellular protein sorting complex, retromer, was required for cell corpse clearance by mediating the recycling of CED-1. Retromer was recruited to the surfaces of phagosomes containing cell corpses, and its loss of function caused defective cell corpse removal. The retromer probably acted through direct interaction with CED-1 in the cell corpse recognition pathway. In the absence of retromer function, CED-1 associated with lysosomes and failed to recycle from phagosomes and cytosol to the plasma membrane. Thus, retromer is an essential mediator of apoptotic cell clearance by regulating phagocytic receptor(s) during cell corpse engulfment.

post to: CiteULike

Regulation of Alternative Splicing by Histone Modifications.

Publication Date: 2010 Feb 4 PMID: 20133523
Authors: Luco, R. F. - Pan, Q. - Tominaga, K. - Blencowe, B. J. - Pereira-Smith, O. M. - Misteli, T.
Journal: Science

Alternative splicing of pre-mRNA is a prominent mechanism to generate protein diversity, yet its regulation is poorly understood. We demonstrated a direct role for histone modifications in alternative splicing. We found distinctive histone modification signatures which correlate with splicing outcome in a set of human genes. Modulation of histone modifications causes splice site switching. Histone marks affect splicing outcome by directly modulating the recruitment of splicing regulators via a chromatin-binding protein. These results outline an adaptor system for reading of histone marks by the pre-mRNA splicing machinery.

post to: CiteULike

Reconstructing Past Seawater Mg/Ca and Sr/Ca from Mid-Ocean Ridge Flank Calcium Carbonate Veins.

Publication Date: 2010 Feb 4 PMID: 20133522
Authors: Coggon, R. M. - Teagle, D. A. - Smith-Duque, C. E. - Alt, J. C. - Cooper, M. J.
Journal: Science

Proxies for past seawater chemistry such as Mg/Ca and Sr/Ca ratios provide a record of the dynamic exchanges of elements between the solid Earth, atmosphere and hydrosphere, and the evolving influence of life. Here, we estimate past oceanic Mg/Ca and Sr/Ca ratios from suites of 1.6 to 170-million-year-old calcium carbonate veins precipitated from seawater-derived fluids in ocean ridge flank basalts. Our data indicate that prior to the Neogene, oceanic Mg/Ca and Sr/Ca were lower than in the modern ocean. Decreased ocean spreading since the Cretaceous and the resulting slow reduction in ocean crustal hydrothermal exchange throughout the early Tertiary may explain the recent rise in these ratios.

post to: CiteULike

Plumage Color Patterns of an Extinct Dinosaur.

Publication Date: 2010 Feb 4 PMID: 20133521
Authors: Li, Q. - Gao, K. Q. - Vinther, J. - Shawkey, M. D. - Clarke, J. A. - D'Alba, L. - Meng, Q. - Briggs, D. E. - Miao, L. - Prum, R. O.
Journal: Science

As long as dinosaurs have been known, there has been speculation about their appearance. Fossil feathers can preserve the morphology of color-imparting melanosomes, which allows color patterns in feathered dinosaurs to be reconstructed. Here, we map feather color patterns in a Late Jurassic basal paravian theropod dinosaur. Quantitative comparisons with melanosome shape and density in extant feathers indicate that the body was gray and dark and the face had rufous speckles. The crown was rufous, and the long limb feathers were white with distal black spangles. The evolution of melanin-based within-feather pigmentation patterns may coincide with that of elongate pennaceous feathers in the common ancestor of Maniraptora, before active powered flight. Feathers may thus have played a role in sexual selection or other communication.

post to: CiteULike

NMR Structure Determination for Larger Proteins Using Backbone-Only Data.

Publication Date: 2010 Feb 4 PMID: 20133520
Authors: Raman, S. - Lange, O. F. - Rossi, P. - Tyka, M. - Wang, X. - Aramini, J. - Liu, G. - Ramelot, T. - Eletsky, A. - Szyperski, T. - Kennedy, M. - Prestegard, J. - Montelione, G. T. - Baker, D.
Journal: Science

Conventional protein structure determination from nuclear magnetic resonance data relies heavily on side-chain proton-proton distances. The necessary side-chain resonance assignment, however, is labor-intensive and prone to error. Here, we show that structures can be accurately determined without NMR information on the sidechains for proteins up to 25 kDa by incorporating backbone chemical shifts, residual dipolar couplings, and amide proton distances into the Rosetta protein structure modelling methodology. These data, which are too sparse for conventional methods, serve only to guide conformational search towards the lowest energy conformations in the folding landscape; the details of the computed models are determined by the physical chemistry implicit in the Rosetta all atom energy function. The new method is not hindered by the deuteration required to suppress nuclear relaxation processes for proteins greater than 15 kDa, and should enable routine NMR structure determination for larger proteins.

post to: CiteULike

Direct restart of a replication fork stalled by a head-on RNA polymerase.

Publication Date: 2010 Jan 29 PMID: 20110508
Authors: Pomerantz, R. T. - O'Donnell, M.
Journal: Science

In vivo studies suggest that replication forks are arrested by encounters with head-on transcription complexes. Yet, the fate of the replisome and RNA polymerase (RNAP) after a head-on collision is unknown. We found that the Escherichia coli replisome stalls upon collision with a head-on transcription complex, but instead of collapsing, the replication fork remains highly stable and eventually resumes elongation after displacing the RNAP from DNA. We also found that the transcription-repair coupling factor Mfd promotes direct restart of the fork after the collision by facilitating displacement of the RNAP. These findings demonstrate the intrinsic stability of the replication apparatus and a previously unknown role for the transcription-coupled repair pathway in promoting replication past a RNAP block.

post to: CiteULike

The asynchronous state in cortical circuits.

Publication Date: 2010 Jan 29 PMID: 20110507
Authors: Renart, A. - de la Rocha, J. - Bartho, P. - Hollender, L. - Parga, N. - Reyes, A. - Harris, K. D.
Journal: Science

Correlated spiking is often observed in cortical circuits, but its functional role is controversial. It is believed that correlations are a consequence of shared inputs between nearby neurons and could severely constrain information decoding. Here we show theoretically that recurrent neural networks can generate an asynchronous state characterized by arbitrarily low mean spiking correlations despite substantial amounts of shared input. In this state, spontaneous fluctuations in the activity of excitatory and inhibitory populations accurately track each other, generating negative correlations in synaptic currents which cancel the effect of shared input. Near-zero mean correlations were seen experimentally in recordings from rodent neocortex in vivo. Our results suggest a reexamination of the sources underlying observed correlations and their functional consequences for information processing.

post to: CiteULike

Decorrelated neuronal firing in cortical microcircuits.

Publication Date: 2010 Jan 29 PMID: 20110506
Authors: Ecker, A. S. - Berens, P. - Keliris, G. A. - Bethge, M. - Logothetis, N. K. - Tolias, A. S.
Journal: Science

Correlated trial-to-trial variability in the activity of cortical neurons is thought to reflect the functional connectivity of the circuit. Many cortical areas are organized into functional columns, in which neurons are believed to be densely connected and to share common input. Numerous studies report a high degree of correlated variability between nearby cells. We developed chronically implanted multitetrode arrays offering unprecedented recording quality to reexamine this question in the primary visual cortex of awake macaques. We found that even nearby neurons with similar orientation tuning show virtually no correlated variability. Our findings suggest a refinement of current models of cortical microcircuit architecture and function: Either adjacent neurons share only a few percent of their inputs or, alternatively, their activity is actively decorrelated.

post to: CiteULike

Platelets amplify inflammation in arthritis via collagen-dependent microparticle production.

Publication Date: 2010 Jan 29 PMID: 20110505
Authors: Boilard, E. - Nigrovic, P. A. - Larabee, K. - Watts, G. F. - Coblyn, J. S. - Weinblatt, M. E. - Massarotti, E. M. - Remold-O'Donnell, E. - Farndale, R. W. - Ware, J. - Lee, D. M.
Journal: Science

In addition to their pivotal role in thrombosis and wound repair, platelets participate in inflammatory responses. We investigated the role of platelets in the autoimmune disease rheumatoid arthritis. We identified platelet microparticles--submicrometer vesicles elaborated by activated platelets--in joint fluid from patients with rheumatoid arthritis and other forms of inflammatory arthritis, but not in joint fluid from patients with osteoarthritis. Platelet microparticles were proinflammatory, eliciting cytokine responses from synovial fibroblasts via interleukin-1. Consistent with these findings, depletion of platelets attenuated murine inflammatory arthritis. Using both pharmacologic and genetic approaches, we identified the collagen receptor glycoprotein VI as a key trigger for platelet microparticle generation in arthritis pathophysiology. Thus, these findings demonstrate a previously unappreciated role for platelets and their activation-induced microparticles in inflammatory joint diseases.

post to: CiteULike

Anciently asexual bdelloid rotifers escape lethal fungal parasites by drying up and blowing away.

Publication Date: 2010 Jan 29 PMID: 20110504
Authors: Wilson, C. G. - Sherman, P. W.
Journal: Science

Asexuality has major theoretical advantages over sexual reproduction. An important evolutionary puzzle, therefore, is why exclusively asexual metazoan lineages rarely endure. The Red Queen hypothesis posits that asexuality is rapidly extinguished by relentlessly coevolving parasites and pathogens. If so, any long-lasting asexual lineage must have unusual alternative mechanisms to deal with these biotic enemies. Bdelloid rotifers are freshwater invertebrates that abandoned sexual reproduction millions of years ago. Here, we show that cultured populations of bdelloids can rid themselves of a deadly fungal parasite through complete desiccation (anhydrobiosis) and disperse by wind to establish new populations in its absence. In Red Queen models, spatiotemporal escape can decouple and protect asexuals from coevolving enemies. Thus, our results may help to explain the persistence of the anciently asexual Bdelloidea.

post to: CiteULike

A basal alvarezsauroid theropod from the early Late Jurassic of Xinjiang, China.

Publication Date: 2010 Jan 29 PMID: 20110503
Authors: Choiniere, J. N. - Xu, X. - Clark, J. M. - Forster, C. A. - Guo, Y. - Han, F.
Journal: Science

The fossil record of Jurassic theropod dinosaurs closely related to birds remains poor. A new theropod from the earliest Late Jurassic of western China represents the earliest diverging member of the enigmatic theropod group Alvarezsauroidea and confirms that this group is a basal member of Maniraptora, the clade containing birds and their closest theropod relatives. It extends the fossil record of Alvarezsauroidea by 63 million years and provides evidence for maniraptorans earlier in the fossil record than Archaeopteryx. The new taxon confirms extreme morphological convergence between birds and derived alvarezsauroids and illuminates incipient stages of the highly modified alvarezsaurid forelimb.

post to: CiteULike

Combined effects on selectivity in Fe-catalyzed methylene oxidation.

Publication Date: 2010 Jan 29 PMID: 20110502
Authors: Chen, M. S. - White, M. C.
Journal: Science

Methylene C-H bonds are among the most difficult chemical bonds to selectively functionalize because of their abundance in organic structures and inertness to most chemical reagents. Their selective oxidations in biosynthetic pathways underscore the power of such reactions for streamlining the synthesis of molecules with complex oxygenation patterns. We report that an iron catalyst can achieve methylene C-H bond oxidations in diverse natural-product settings with predictable and high chemo-, site-, and even diastereoselectivities. Electronic, steric, and stereoelectronic factors, which individually promote selectivity with this catalyst, are demonstrated to be powerful control elements when operating in combination in complex molecules. This small-molecule catalyst displays site selectivities complementary to those attained through enzymatic catalysis.

post to: CiteULike

A tricyclic aromatic isomer of hexasilabenzene.

Publication Date: 2010 Jan 29 PMID: 20110501
Authors: Abersfelder, K. - White, A. J. - Rzepa, H. S. - Scheschkewitz, D.
Journal: Science

Benzene represents the showcase of Huckel aromaticity. The silicon analog, hexasilabenzene, has consequently been targeted for decades. We now report an intensely green isomer of Si6R6 (R being 2,4,6-triisopropylphenyl) with a tricyclic structure in the solid state featuring silicon atoms with two, one, and no substituents outside the ring framework. The highly dispersed 29Si nuclear magnetic resonance shifts in solution ranging from +125 to -90 parts per million indicate an inhomogeneous electron distribution due to the dismutation of formal oxidation numbers as compared with that of benzene. Theoretical analysis reveals nonetheless the cyclic delocalization of six mobile electrons of the pi-, sigma- and non-bonding type across the central four-membered ring. For this alternative form of aromaticity, in principle applicable to many Huckel aromatic species, we propose the term dismutational aromaticity.

post to: CiteULike

The free-energy landscape of clusters of attractive hard spheres.

Publication Date: 2010 Jan 29 PMID: 20110500
Authors: Meng, G. - Arkus, N. - Brenner, M. P. - Manoharan, V. N.
Journal: Science

The study of clusters has provided a tangible link between local geometry and bulk condensed matter, but experiments have not yet systematically explored the thermodynamics of the smallest clusters. Here we present experimental measurements of the structures and free energies of colloidal clusters in which the particles act as hard spheres with short-range attractions. We found that highly symmetric clusters are strongly suppressed by rotational entropy, whereas the most stable clusters have anharmonic vibrational modes or extra bonds. Many of these clusters are subsets of close-packed lattices. As the number of particles increases from 6 to 10, we observe the emergence of a complex free-energy landscape with a small number of ground states and many local minima.

post to: CiteULike

Phase transitions of adsorbed atoms on the surface of a carbon nanotube.

Publication Date: 2010 Jan 29 PMID: 20110499
Authors: Wang, Z. - Wei, J. - Morse, P. - Dash, J. G. - Vilches, O. E. - Cobden, D. H.
Journal: Science

Phase transitions of adsorbed atoms and molecules on two-dimensional substrates are well explored, but similar transitions in the one-dimensional limit have been more difficult to study experimentally. Suspended carbon nanotubes can act as nanoscale resonators with remarkable electromechanical properties and the ability to detect adsorption at the level of single atoms. We used single-walled carbon nanotube resonators to study the phase behavior of adsorbed argon and krypton atoms as well as their coupling to the substrate electrons. By monitoring the resonance frequency in the presence of gases, we observed the formation of monolayers on the cylindrical surface, phase transitions within them, and simultaneous modification of the electrical conductance.

post to: CiteULike

Local and long-range reciprocal regulation of cAMP and cGMP in axon/dendrite formation.

Publication Date: 2010 Jan 29 PMID: 20110498
Authors: Shelly, M. - Lim, B. K. - Cancedda, L. - Heilshorn, S. C. - Gao, H. - Poo, M. M.
Journal: Science

Cytosolic cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) often mediate antagonistic cellular actions of extracellular factors, from the regulation of ion channels to cell volume control and axon guidance. We found that localized cAMP and cGMP activities in undifferentiated neurites of cultured hippocampal neurons promote and suppress axon formation, respectively, and exert opposite effects on dendrite formation. Fluorescence resonance energy transfer imaging showed that alterations of the amount of cAMP resulted in opposite changes in the amount of cGMP, and vice versa, through the activation of specific phosphodiesterases and protein kinases. Local elevation of cAMP in one neurite resulted in cAMP reduction in all other neurites of the same neuron. Thus, local and long-range reciprocal regulation of cAMP and cGMP together ensures coordinated development of one axon and multiple dendrites.

post to: CiteULike

Role of ABA and ABI3 in desiccation tolerance.

Publication Date: 2010 Jan 29 PMID: 20110497
Authors: Khandelwal, A. - Cho, S. H. - Marella, H. - Sakata, Y. - Perroud, P. F. - Pan, A. - Quatrano, R. S.
Journal: Science

We show in bryophytes that abscisic acid (ABA) pretreatment of moss (Physcomitrella patens) cells confers desiccation tolerance. In angiosperms, both ABA and the transcriptional regulator ABSCISIC ACID INSENSITIVE 3 (ABI3) are required to protect the seed during desiccation. ABA was not able to protect moss cells in stable deletion lines of ABI3 (DeltaPpabi3). Hence, moss has the same functional link between ABA, ABI3, and the desiccation tolerance phenotype that is found in angiosperms. Furthermore, we identified 22 genes that were induced during ABA pretreatment in wild-type lines. When their expression was compared with that of DeltaPpabi3 during ABA pretreatment and immediately after desiccation, a new target of ABI3 action appears to be in the recovery period.

post to: CiteULike

Coexistence of quiescent and active adult stem cells in mammals.

Publication Date: 2010 Jan 29 PMID: 20110496
Authors: Li, L. - Clevers, H.
Journal: Science

Adult stem cells are crucial for physiological tissue renewal and regeneration after injury. Prevailing models assume the existence of a single quiescent population of stem cells residing in a specialized niche of a given tissue. Emerging evidence indicates that both quiescent (out of cell cycle and in a lower metabolic state) and active (in cell cycle and not able to retain DNA labels) stem cell subpopulations may coexist in several tissues, in separate yet adjoining locations. Here, we summarize these findings and propose that quiescent and active stem cell populations have separate but cooperative functional roles.

post to: CiteULike

Winner of Science Prize for Online Resources in Education. Making genetics easy to understand.

Publication Date: 2010 Jan 29 PMID: 20110495
Authors: Stark, L. A. - Pompei, K.
Journal: Science

post to: CiteULike

Retrospective. Edwin G. Krebs (1918-2009).

Publication Date: 2010 Jan 29 PMID: 20110494
Authors: Catterall, W. A. - Scott, J. D.
Journal: Science

post to: CiteULike

Materials science. Turning away from high symmetry.

Publication Date: 2010 Jan 29 PMID: 20110493
Authors: Crocker, J. C.
Journal: Science

post to: CiteULike

Economics. Measuring subjective well-being.

Publication Date: 2010 Jan 29 PMID: 20110492
Authors: Layard, R.
Journal: Science

post to: CiteULike

Anthropology. Apes among the tangled branches of human origins.

Publication Date: 2010 Jan 29 PMID: 20110491
Authors: Harrison, T.
Journal: Science

post to: CiteULike

Atmospheric science. A test for geoengineering?

Publication Date: 2010 Jan 29 PMID: 20110490
Authors: Robock, A. - Bunzl, M. - Kravitz, B. - Stenchikov, G. L.
Journal: Science

post to: CiteULike

Materials science. Bundling with x-rays.

Publication Date: 2010 Jan 29 PMID: 20110489
Authors: Safinya, C. R. - Li, Y.
Journal: Science

post to: CiteULike

Immunology. Arsonists in rheumatoid arthritis.

Publication Date: 2010 Jan 29 PMID: 20110488
Authors: Zimmerman, G. A. - Weyrich, A. S.
Journal: Science

post to: CiteULike

Climate change. The politics of geoengineering.

Publication Date: 2010 Jan 29 PMID: 20110487
Authors: Blackstock, J. J. - Long, J. C.
Journal: Science

post to: CiteULike

Taking a cue from the silver screen.

Publication Date: 2010 Jan 29 PMID: 20110486
Authors: Faulkes, Z.
Journal: Science

post to: CiteULike

Give the "fair sex" a fair shake.

Publication Date: 2010 Jan 29 PMID: 20110485
Authors: Nestle, M.
Journal: Science

post to: CiteULike

Tracking the source of glacier misinformation.

Publication Date: 2010 Jan 29 PMID: 20110484
Authors: Cogley, J. G. - Kargel, J. S. - Kaser, G. - van der Veen, C. J.
Journal: Science

post to: CiteULike

A role for postdocs in undergraduate education.

Publication Date: 2010 Jan 29 PMID: 20110483
Authors: Bush, S. D. - Pelaez, N. J. - Rudd, J. A. - Stevens, M. T. - Tanner, K. D. - Williams, K. S. - Wood, W. B.
Journal: Science

post to: CiteULike

Research facilities. Little castle on the prairie.

Publication Date: 2010 Jan 29 PMID: 20110482
Authors: Kean, S.
Journal: Science

post to: CiteULike

Evolution. In the deep blue sea.

Publication Date: 2010 Jan 29 PMID: 20110481
Authors: Pennisi, E.
Journal: Science

post to: CiteULike

Faintest thrum heralds quantum machines.

Publication Date: 2010 Jan 29 PMID: 20110480
Authors: Cho, A.
Journal: Science

post to: CiteULike

Planetary science. Did a battering rain of comets bring Ganymede to geologic life?

Publication Date: 2010 Jan 29 PMID: 20110479
Authors: Kerr, R. A.
Journal: Science

post to: CiteULike

Physics. Test shots show laser-fusion experiment is on target.

Publication Date: 2010 Jan 29 PMID: 20110477
Authors: Clery, D.
Journal: Science

post to: CiteULike

Fisheries. In central California, coho salmon are on the brink.

Publication Date: 2010 Jan 29 PMID: 20110475
Authors: Miller, G.
Journal: Science

post to: CiteULike

Physics. NRC urges U.S. to rethink sale of helium reserve.

Publication Date: 2010 Jan 29 PMID: 20110474
Authors: Cho, A.
Journal: Science

post to: CiteULike

Newsmaker interview. Climate science leader Rajendra Pachauri confronts the critics. Interview by Pallava Bagla.

Publication Date: 2010 Jan 29 PMID: 20110473
Authors: Pachauri, R. K.
Journal: Science

post to: CiteULike

Global health. Haiti's quake shifts clinic's focus from AIDS to aid. Interview by Jon Cohen.

Publication Date: 2010 Jan 29 PMID: 20110472
Authors: Pape, J.
Journal: Science

post to: CiteULike

Paleontology. Bird-dinosaur link firmed up, and in brilliant Technicolor.

Publication Date: 2010 Jan 29 PMID: 20110471
Authors: Stone, R.
Journal: Science

post to: CiteULike

Science education web sites.

Publication Date: 2010 Jan 29 PMID: 20110470
Authors: Alberts, B.
Journal: Science

post to: CiteULike

Generating a Prion with Bacterially Expressed Recombinant Prion Protein.

Publication Date: 2010 Jan 28 PMID: 20110469
Authors: Wang, F. - Wang, X. - Yuan, C. G. - Ma, J.
Journal: Science

The prion hypothesis posits that a misfolded form of prion protein (PrP) is responsible for the infectivity of prion disease. Using recombinant murine PrP purified from Escherichia coli, we created a recombinant prion with the hallmarks of the pathogenic PrP isoform: aggregated, protease-resistant, and self-perpetuating. After intracerebral injection of the recombinant prion, wild-type mice developed neurological signs in ~130 days and reached the terminal stage of disease in ~150 days. Characterization of diseased mice revealed classic neuropathology of prion disease, the presence of protease-resistant PrP, and the capability of serially transmitting the disease, confirming that these mice succumbed to prion disease. Thus, as postulated by the prion hypothesis, the infectivity in mammalian prion disease results from an altered conformation of PrP.

post to: CiteULike

N-Terminal Acetylation of Cellular Proteins Creates Specific Degradation Signals.

Publication Date: 2010 Jan 28 PMID: 20110468
Authors: Hwang, C. S. - Shemorry, A. - Varshavsky, A.
Journal: Science

The retained N-terminal methionine (Met) residue of a nascent protein is often N-terminally acetylated (Nt-acetylated). Removal of N-terminal Met by Met-aminopeptidases frequently leads to Nt-acetylation of the resulting N-terminal Ala, Val, Ser, Thr, and Cys residues. Although a majority of eukaryotic proteins-for example, more than 80% of human proteins-are cotranslationally Nt-acetylated, the function of this extensively studied modification is largely unknown. Here, we found, using the yeast Saccharomyces cerevisiae, that the Nt-acetylated Met residue could act as a degradation signal (degron), targeted by the Doa10 ubiquitin ligase. Moreover, Doa10 also recognized the Nt-acetylated Ala, Val, Ser, Thr, and Cys residues. Several examined proteins of diverse functions contained these N-terminal degrons, termed (Ac)N-degrons, which comprise a prevalent class of degradation signals in cellular proteins.

post to: CiteULike

Food Security: The Challenge of Feeding 9 Billion People.

Publication Date: 2010 Jan 28 PMID: 20110467
Authors: Godfray, H. C. - Beddington, J. R. - Crute, I. R. - Haddad, L. - Lawrence, D. - Muir, J. F. - Pretty, J. - Robinson, S. - Thomas, S. M. - Toulmin, C.
Journal: Science

Continuing population and consumption growth will mean that the global demand for food will increase for at least another 40 years. Growing competition for land, water, and energy, and the overexploitation of fisheries, will affect our ability to produce food, as will the urgent requirement to reduce the impact of the food system on the environment. The effects of climate change are a further threat. But the world can produce more food, and can ensure that it is used more efficiently and equitably. A multifaceted and linked global strategy is needed to ensure sustainable and equitable food security, different components of which are explored here.

post to: CiteULike

Contributions of Stratospheric Water Vapor to Decadal Changes in the Rate of Global Warming.

Publication Date: 2010 Jan 28 PMID: 20110466
Authors: Solomon, S. - Rosenlof, K. - Portmann, R. - Daniel, J. - Davis, S. - Sanford, T. - Plattner, G. K.
Journal: Science

Stratospheric water vapor concentrations decreased by about 10% after the year 2000. Here, we show that this acted to slow the rate of increase in global surface temperature over 2000 to 2009 by about 25% compared to that which would have occurred due only to carbon dioxide and other greenhouse gases. More limited data suggest that stratospheric water vapor probably increased between 1980 and 2000, which would have enhanced the decadal rate of surface warming during the 1990s by about 30% compared to estimates neglecting this change. These findings show that stratospheric water vapor represents an important driver of decadal global surface climate change.

post to: CiteULike

Symmetric Inertial Confinement Fusion Implosions at Ultra-High Laser Energies.

Publication Date: 2010 Jan 28 PMID: 20110465
Authors: Glenzer, S. H. - Macgowan, B. J. - Michel, P. - Meezan, N. B. - Suter, L. J. - Dixit, S. N. - Kline, J. L. - Kyrala, G. A. - Bradley, D. K. - Callahan, D. A. - Dewald, E. L. - Divol, L. - Dzenitis, E. - Edwards, M. J. - Hamza, A. V. - Haynam, C. A. - Hinkel, D. E. - Kalantar, D. H. - Kilkenny, J. D. - Landen, O. L. - Lindl, J. D. - Lepape, S. - Moody, J. D. - Nikroo, A. - Parham, T. - Schneider, M. B. - Town, R. P. - Wegner, P. - Widmann, K. - Whitman, P. - Young, B. K. - Van Wonterghem, B. - Atherton, L. J. - Moses, E. I.
Journal: Science

Indirect-drive hohlraum experiments at the National Ignition Facility have demonstrated symmetric capsule implosions at unprecedented laser drive energies of 0.7 MJ. One hundred and ninety-two simultaneously fired laser beams heat ignition emulate hohlraums to radiation temperatures of 3.3 million Kelvin, compressing 1.8-mm capsules by the soft x-rays produced by the hohlraum. Self-generated plasma-optics gratings on either end of the hohlraum tune the laser power distribution in the hohlraum producing symmetric x-ray drive as inferred from the shape of the capsule self-emission. These experiments indicate conditions suitable for compressing deuterium-tritium filled capsules with the goal to achieve burning fusion plasmas and energy gain in the laboratory.

post to: CiteULike

Charged-Particle Probing of X-ray-Driven Inertial-Fusion Implosions.

Publication Date: 2010 Jan 28 PMID: 20110464
Authors: Li, C. K. - Seguin, F. H. - Frenje, J. A. - Rosenberg, M. - Petrasso, R. D. - Amendt, P. A. - Koch, J. A. - Landen, O. L. - Park, H. S. - Robey, H. F. - Town, R. P. - Casner, A. - Philippe, F. - Betti, R. - Knauer, J. P. - Meyerhofer, D. D. - Back, C. A. - Kilkenny, J. D. - Nikroo, A.
Journal: Science

Measurements of x-ray-driven implosions with charged particles have resulted in the quantitative characterization of critical aspects of indirect-drive inertial fusion. Three types of spontaneous electric fields differing in strength by two orders of magnitude, the largest being nearly one-tenth of the Bohr field, were discovered with time-gated proton radiographic imaging and spectrally resolved proton self-emission. The views of the spatial structure and temporal evolution of both the laser drive in a hohlraum and implosion properties provide essential insight into, and modeling validation of, x-ray-driven implosions.

post to: CiteULike

Impact of spikelets on hippocampal CA1 pyramidal cell activity during spatial exploration.

Publication Date: 2010 Jan 22 PMID: 20093475
Authors: Epsztein, J. - Lee, A. K. - Chorev, E. - Brecht, M.
Journal: Science

In vivo intracellular recordings of hippocampal neurons reveal the occurrence of fast events of small amplitude called spikelets or fast prepotentials. Because intracellular recordings have been restricted to anesthetized or head-fixed animals, it is not known how spikelet activity contributes to hippocampal spatial representations. We addressed this question in CA1 pyramidal cells by using in vivo whole-cell recording in freely moving rats. We observed a high incidence of spikelets that occurred either in isolation or in bursts and could drive spiking as fast prepotentials of action potentials. Spikelets strongly contributed to spiking activity, driving approximately 30% of all action potentials. CA1 pyramidal cell firing and spikelet activity were comodulated as a function of the animal's location in the environment. We conclude that spikelets have a major impact on hippocampal activity during spatial exploration.

MeSH Categories: *Action Potentials, Animals, CA1 Region, Hippocampal/cytology/*physiology, *Exploratory Behavior, Male, Maze Learning, Patch-Clamp Techniques, Pyramidal Cells/*physiology, Rats, Rats, Wistar, *Space Perception

post to: CiteULike

Evolution of MRSA during hospital transmission and intercontinental spread.

Publication Date: 2010 Jan 22 PMID: 20093474
Authors: Harris, S. R. - Feil, E. J. - Holden, M. T. - Quail, M. A. - Nickerson, E. K. - Chantratita, N. - Gardete, S. - Tavares, A. - Day, N. - Lindsay, J. A. - Edgeworth, J. D. - de Lencastre, H. - Parkhill, J. - Peacock, S. J. - Bentley, S. D.
Journal: Science

Current methods for differentiating isolates of predominant lineages of pathogenic bacteria often do not provide sufficient resolution to define precise relationships. Here, we describe a high-throughput genomics approach that provides a high-resolution view of the epidemiology and microevolution of a dominant strain of methicillin-resistant Staphylococcus aureus (MRSA). This approach reveals the global geographic structure within the lineage, its intercontinental transmission through four decades, and the potential to trace person-to-person transmission within a hospital environment. The ability to interrogate and resolve bacterial populations is applicable to a range of infectious diseases, as well as microbial ecology.

MeSH Categories: Asia/epidemiology, Bacterial Typing Techniques, Cross Infection/epidemiology/*microbiology/transmission, Europe/epidemiology, Evolution, Molecular, *Genome, Bacterial, Genomics/methods, Humans, Likelihood Functions, Methicillin-Resistant Staphylococcus, aureus/*classification/*genetics/isolation & purification, Molecular Epidemiology, Molecular Sequence Data, Phylogeny, Polymorphism, Single Nucleotide, Sequence Analysis, DNA, South America/epidemiology, Staphylococcal Infections/epidemiology/*microbiology/transmission, Time Factors, United States/epidemiology

post to: CiteULike

Identification of RACK1 and protein kinase Calpha as integral components of the mammalian circadian clock.

Publication Date: 2010 Jan 22 PMID: 20093473
Authors: Robles, M. S. - Boyault, C. - Knutti, D. - Padmanabhan, K. - Weitz, C. J.
Journal: Science

At the core of the mammalian circadian clock is a negative feedback loop in which the dimeric transcription factor CLOCK-BMAL1 drives processes that in turn suppress its transcriptional activity. To gain insight into the mechanisms of circadian feedback, we analyzed mouse protein complexes containing BMAL1. Receptor for activated C kinase-1 (RACK1) and protein kinase C-alpha (PKCalpha) were recruited in a circadian manner into a nuclear BMAL1 complex during the negative feedback phase of the cycle. Overexpression of RACK1 and PKCalpha suppressed CLOCK-BMAL1 transcriptional activity, and RACK1 stimulated phosphorylation of BMAL1 by PKCalpha in vitro. Depletion of endogenous RACK1 or PKCalpha from fibroblasts shortened the circadian period, demonstrating that both molecules function in the clock oscillatory mechanism. Thus, the classical PKC signaling pathway is not limited to relaying external stimuli but is rhythmically activated by internal processes, forming an integral part of the circadian feedback loop.

MeSH Categories: ARNTL Transcription Factors/metabolism, Animals, CLOCK Proteins/metabolism, Cell Nucleus/metabolism, Circadian Rhythm/*physiology, Feedback, Physiological, Fibroblasts/metabolism/physiology, Mice, Mice, Inbred C57BL, Neuropeptides/genetics/*metabolism, Phosphorylation, Protein Binding, Protein Kinase C-alpha/*metabolism, RNA Interference, Signal Transduction, Transcription, Genetic

post to: CiteULike

Requirement of prorenin receptor and vacuolar H+-ATPase-mediated acidification for Wnt signaling.

Publication Date: 2010 Jan 22 PMID: 20093472
Authors: Cruciat, C. M. - Ohkawara, B. - Acebron, S. P. - Karaulanov, E. - Reinhard, C. - Ingelfinger, D. - Boutros, M. - Niehrs, C.
Journal: Science

Wnt/beta-catenin signaling is important in stem cell biology, embryonic development, and disease, including cancer. However, the mechanism of Wnt signal transmission, notably how the receptors are activated, remains incompletely understood. We found that the prorenin receptor (PRR) is a component of the Wnt receptor complex. PRR functions in a renin-independent manner as an adaptor between Wnt receptors and the vacuolar H+-adenosine triphosphatase (V-ATPase) complex. Moreover, PRR and V-ATPase were required to mediate Wnt signaling during antero-posterior patterning of Xenopus early central nervous system development. The results reveal an unsuspected role for the prorenin receptor, V-ATPase activity, and acidification during Wnt/beta-catenin signaling.

MeSH Categories: Animals, Body Patterning, Cell Line, Cell Line, Tumor, Central Nervous System/cytology/embryology, Embryo, Nonmammalian/metabolism, Frizzled Receptors/metabolism, Gene Expression Regulation, Developmental, Homeodomain Proteins/genetics/metabolism, Humans, Hydrogen-Ion Concentration, LDL-Receptor Related Proteins/metabolism, Mice, Nerve Tissue Proteins/genetics/metabolism, Phosphorylation, RNA, Small Interfering, Receptors, Cell Surface/genetics/*metabolism, *Signal Transduction, Vacuolar Proton-Translocating ATPases/antagonists & inhibitors/*metabolism, Wnt Proteins/*metabolism, Xenopus/embryology/metabolism, Xenopus Proteins/genetics/*metabolism, beta Catenin/metabolism

post to: CiteULike

Modeled impact of anthropogenic warming on the frequency of intense Atlantic hurricanes.

Publication Date: 2010 Jan 22 PMID: 20093471
Authors: Bender, M. A. - Knutson, T. R. - Tuleya, R. E. - Sirutis, J. J. - Vecchi, G. A. - Garner, S. T. - Held, I. M.
Journal: Science

Several recent models suggest that the frequency of Atlantic tropical cyclones could decrease as the climate warms. However, these models are unable to reproduce storms of category 3 or higher intensity. We explored the influence of future global warming on Atlantic hurricanes with a downscaling strategy by using an operational hurricane-prediction model that produces a realistic distribution of intense hurricane activity for present-day conditions. The model projects nearly a doubling of the frequency of category 4 and 5 storms by the end of the 21st century, despite a decrease in the overall frequency of tropical cyclones, when the downscaling is based on the ensemble mean of 18 global climate-change projections. The largest increase is projected to occur in the Western Atlantic, north of 20 degrees N.

post to: CiteULike

Contribution of semi-arid forests to the climate system.

Publication Date: 2010 Jan 22 PMID: 20093470
Authors: Rotenberg, E. - Yakir, D.
Journal: Science

Forests both take up CO2 and enhance absorption of solar radiation, with contrasting effects on global temperature. Based on a 9-year study in the forests' dry timberline, we show that substantial carbon sequestration (cooling effect) is maintained in the large dry transition zone (precipitation from 200 to 600 millimeters) by shifts in peak photosynthetic activities from summer to early spring, and this is counteracted by longwave radiation (L) suppression (warming effect), doubling the forestation shortwave (S) albedo effect. Several decades of carbon accumulation are required to balance the twofold S + L effect. Desertification over the past several decades, however, contributed negative forcing at Earth's surface equivalent to approximately 20% of the global anthropogenic CO2 effect over the same period, moderating warming trends.

MeSH Categories: Carbon/*metabolism, Carbon Dioxide/metabolism, *Climatic Processes, Conservation of Natural Resources, *Ecosystem, Geography, Israel, Photosynthesis, Seasons, Temperature, *Trees/growth & development/metabolism

post to: CiteULike

Direct measurements of island growth and step-edge barriers in colloidal epitaxy.

Publication Date: 2010 Jan 22 PMID: 20093469
Authors: Ganapathy, R. - Buckley, M. R. - Gerbode, S. J. - Cohen, I.
Journal: Science

Epitaxial growth, a bottom-up self-assembly process for creating surface nano- and microstructures, has been extensively studied in the context of atoms. This process, however, is also a promising route to self-assembly of nanometer- and micrometer-scale particles into microstructures that have numerous technological applications. To determine whether atomic epitaxial growth laws are applicable to the epitaxy of larger particles with attractive interactions, we investigated the nucleation and growth dynamics of colloidal crystal films with single-particle resolution. We show quantitatively that colloidal epitaxy obeys the same two-dimensional island nucleation and growth laws that govern atomic epitaxy. However, we found that in colloidal epitaxy, step-edge and corner barriers that are responsible for film morphology have a diffusive origin. This diffusive mechanism suggests new routes toward controlling film morphology during epitaxy.

post to: CiteULike

Measurement of universal thermodynamic functions for a unitary Fermi gas.

Publication Date: 2010 Jan 22 PMID: 20093468
Authors: Horikoshi, M. - Nakajima, S. - Ueda, M. - Mukaiyama, T.
Journal: Science

Thermodynamic properties of matter generally depend on the details of interactions between its constituent parts. However, in a unitary Fermi gas where the scattering length diverges, thermodynamics is determined through universal functions that depend only on the particle density and temperature. By using only the general form of the equation of state and the equation of force balance, we measured the local internal energy of the trapped gas as a function of these parameters. Other universal functions, such as those corresponding to the Helmholtz free energy, chemical potential, and entropy, were calculated through general thermodynamic relations. The critical parameters were also determined at the superfluid transition temperature. These results apply to all strongly interacting fermionic systems, including neutron stars and nuclear matter.

post to: CiteULike

Rules for biologically inspired adaptive network design.

Publication Date: 2010 Jan 22 PMID: 20093467
Authors: Tero, A. - Takagi, S. - Saigusa, T. - Ito, K. - Bebber, D. P. - Fricker, M. D. - Yumiki, K. - Kobayashi, R. - Nakagaki, T.
Journal: Science

Transport networks are ubiquitous in both social and biological systems. Robust network performance involves a complex trade-off involving cost, transport efficiency, and fault tolerance. Biological networks have been honed by many cycles of evolutionary selection pressure and are likely to yield reasonable solutions to such combinatorial optimization problems. Furthermore, they develop without centralized control and may represent a readily scalable solution for growing networks in general. We show that the slime mold Physarum polycephalum forms networks with comparable efficiency, fault tolerance, and cost to those of real-world infrastructure networks--in this case, the Tokyo rail system. The core mechanisms needed for adaptive network formation can be captured in a biologically inspired mathematical model that may be useful to guide network construction in other domains.

MeSH Categories: Algorithms, *Computer Simulation, Food, *Models, Biological, Physarum polycephalum/*cytology/growth & development/*physiology, *Railroads, Systems Biology, Tokyo

post to: CiteULike

The genetic landscape of a cell.

Publication Date: 2010 Jan 22 PMID: 20093466
Authors: Costanzo, M. - Baryshnikova, A. - Bellay, J. - Kim, Y. - Spear, E. D. - Sevier, C. S. - Ding, H. - Koh, J. L. - Toufighi, K. - Mostafavi, S. - Prinz, J. - St Onge, R. P. - VanderSluis, B. - Makhnevych, T. - Vizeacoumar, F. J. - Alizadeh, S. - Bahr, S. - Brost, R. L. - Chen, Y. - Cokol, M. - Deshpande, R. - Li, Z. - Lin, Z. Y. - Liang, W. - Marback, M. - Paw, J. - San Luis, B. J. - Shuteriqi, E. - Tong, A. H. - van Dyk, N. - Wallace, I. M. - Whitney, J. A. - Weirauch, M. T. - Zhong, G. - Zhu, H. - Houry, W. A. - Brudno, M. - Ragibizadeh, S. - Papp, B. - Pal, C. - Roth, F. P. - Giaever, G. - Nislow, C. - Troyanskaya, O. G. - Bussey, H. - Bader, G. D. - Gingras, A. C. - Morris, Q. D. - Kim, P. M. - Kaiser, C. A. - Myers, C. L. - Andrews, B. J. - Boone, C.
Journal: Science

A genome-scale genetic interaction map was constructed by examining 5.4 million gene-gene pairs for synthetic genetic interactions, generating quantitative genetic interaction profiles for approximately 75% of all genes in the budding yeast, Saccharomyces cerevisiae. A network based on genetic interaction profiles reveals a functional map of the cell in which genes of similar biological processes cluster together in coherent subsets, and highly correlated profiles delineate specific pathways to define gene function. The global network identifies functional cross-connections between all bioprocesses, mapping a cellular wiring diagram of pleiotropy. Genetic interaction degree correlated with a number of different gene attributes, which may be informative about genetic network hubs in other organisms. We also demonstrate that extensive and unbiased mapping of the genetic landscape provides a key for interpretation of chemical-genetic interactions and drug target identification.

MeSH Categories: Computational Biology, Gene Duplication, Gene Expression Regulation, Fungal, *Gene Regulatory Networks, Genes, Fungal, Genetic Fitness, *Genome, Fungal, Metabolic Networks and Pathways, Mutation, Protein Interaction Mapping, Saccharomyces cerevisiae/*genetics/*metabolism/physiology, Saccharomyces cerevisiae Proteins/genetics/*metabolism

post to: CiteULike

Materials science. Epitaxial growth writ large.

Publication Date: 2010 Jan 22 PMID: 20093465
Authors: Einstein, T. L. - Stasevich, T. J.
Journal: Science

post to: CiteULike

Geochemistry. Adjusting the solar system's absolute clock.

Publication Date: 2010 Jan 22 PMID: 20093464
Authors: Connelly, J. N.
Journal: Science

post to: CiteULike

Paleontology. And then there were none?

Publication Date: 2010 Jan 22 PMID: 20093463
Authors: Roberts, R. G. - Brook, B. W.
Journal: Science

MeSH Categories: Animals, Birds, Carnivora, *Extinction, Biological, *Fossils, Lizards, Marsupialia, New South Wales, Time

post to: CiteULike

Systems biology. Amoeba-inspired network design.

Publication Date: 2010 Jan 22 PMID: 20093462
Authors: Marwan, W.
Journal: Science

MeSH Categories: *Algorithms, *Computer Simulation, Cytoplasm/physiology, Food, *Models, Biological, Morphogenesis, Physarum polycephalum/*cytology/growth & development/*physiology, *Railroads, Systems Biology, Tokyo

post to: CiteULike

Climate. Drylands in the Earth system.

Publication Date: 2010 Jan 22 PMID: 20093461
Authors: Schimel, D. S.
Journal: Science

MeSH Categories: Carbon/*metabolism, Climate Change, *Climatic Processes, Conservation of Natural Resources, *Ecosystem, Geography, Israel, Photosynthesis, Seasons, Temperature, *Trees/growth & development/metabolism

post to: CiteULike

Microbiology. Subversion from the sidelines.

Publication Date: 2010 Jan 22 PMID: 20093460
Authors: Agarwal, N. - Bishai, W. R.
Journal: Science

MeSH Categories: Animals, Antigens, Bacterial/*metabolism, Bacterial Proteins/*metabolism, Embryo, Nonmammalian/microbiology, Enzyme Inhibitors/therapeutic use, Granuloma/*microbiology, Matrix Metalloproteinase 9/antagonists & inhibitors/*metabolism, Mycobacterium Infections, Atypical/metabolism/*microbiology, Mycobacterium marinum/genetics/*pathogenicity, Tuberculosis/drug therapy/microbiology, Virulence Factors/*metabolism, Zebrafish/embryology, Zebrafish Proteins/metabolism

post to: CiteULike

Computer science. Accessible reproducible research.

Publication Date: 2010 Jan 22 PMID: 20093459
Authors: Mesirov, J. P.
Journal: Science

MeSH Categories: Access to Information, Computational Biology/*methods, *Computing Methodologies, Genomics/*methods, Informatics/methods, Internet, *Publishing, Reproducibility of Results, *Research, *Software

post to: CiteULike

East German institutes stand tall.

Publication Date: 2010 Jan 22 PMID: 20093458
Authors: Rietschel, E. T.
Journal: Science

MeSH Categories: *Academies and Institutes/organization & administration, Germany, Germany, East, *Research, Research Personnel

post to: CiteULike

Carbon accounting a tricky business.

Publication Date: 2010 Jan 22 PMID: 20093457
Authors: Friedland, A. J. - Gillingham, K. T.
Journal: Science

MeSH Categories: *Biofuels, *Carbon, Carbon Dioxide

post to: CiteULike

Studying extant species to model our past.

Publication Date: 2010 Jan 22 PMID: 20093456
Authors: Whiten, A. - McGrew, W. C. - Aiello, L. C. - Boesch, C. - Boyd, R. - Byrne, R. W. - Dunbar, R. I. - Matsuzawa, T. - Silk, J. B. - Tomasello, M. - van Schaik, C. P. - Wrangham, R.
Journal: Science

MeSH Categories: Animals, Behavior, Behavior, Animal, Cognition, *Evolution, Female, *Hominidae/classification, Humans, Male, *Pan troglodytes/classification

post to: CiteULike

Fall meeting of the American Geophysical Union, 14-18 December 2009, San Francisco, California. Antarctic glacier off its leash.

Publication Date: 2010 Jan 22 PMID: 20093454
Authors: Kerr, R. A.
Journal: Science

post to: CiteULike

Fall meeting of the American Geophysical Union, 14-18 December 2009, San Francisco, California. Snapshots from the meeting.

Publication Date: 2010 Jan 22 PMID: 20093453
Authors: Kerr, R. A.
Journal: Science

post to: CiteULike

Fall meeting of the American Geophysical Union, 14-18 December 2009, San Francisco, California. Flows on Mars but no water.

Publication Date: 2010 Jan 22 PMID: 20093452
Authors: Kerr, R. A.
Journal: Science

MeSH Categories: *Carbon Dioxide, Extraterrestrial Environment, *Mars, Spacecraft, *Water

post to: CiteULike

Fall meeting of the American Geophysical Union, 14-18 December 2009, San Francisco, California. Magnetics point to magma 'ocean' at Io.

Publication Date: 2010 Jan 22 PMID: 20093451
Authors: Kerr, R. A.
Journal: Science

post to: CiteULike

Science indicators. Trends document China's prowess.

Publication Date: 2010 Jan 22 PMID: 20093450
Authors: Mervis, J.
Journal: Science

post to: CiteULike

Archaeology. The tangled roots of agriculture.

Publication Date: 2010 Jan 22 PMID: 20093449
Authors: Balter, M.
Journal: Science

MeSH Categories: Agriculture/*history, Animals, *Animals, Domestic, *Archaeology, Climate Change/*history, History, Ancient, Humans

post to: CiteULike

Academic freedom. Google plots exit strategy as China shores up 'Great Firewall'.

Publication Date: 2010 Jan 22 PMID: 20093447
Authors: Stone, R. - Xin, H.
Journal: Science

MeSH Categories: *Access to Information/legislation & jurisprudence, China, *Internet/legislation & jurisprudence

post to: CiteULike

Germany. Under fire from pharma, institute may lose its director.

Publication Date: 2010 Jan 22 PMID: 20093446
Authors: Vogel, G.
Journal: Science

MeSH Categories: *Drug Industry, Germany, Government Agencies/*organization & administration, Health Care Reform, *Treatment Outcome

post to: CiteULike

Iran. Killing of professor sparks fight over his science and his politics.

Publication Date: 2010 Jan 22 PMID: 20093445
Authors: Bhattacharjee, Y.
Journal: Science

post to: CiteULike

Scientific cooperation. African physicists set their sights on mammoth scope.

Publication Date: 2010 Jan 22 PMID: 20093443
Authors: Bohannon, J.
Journal: Science

post to: CiteULike

Global warming. Models foresee more-intense hurricanes in the greenhouse.

Publication Date: 2010 Jan 22 PMID: 20093442
Authors: Kerr, R. A.
Journal: Science

post to: CiteULike

Seismology. Foreshadowing Haiti's catastrophe.

Publication Date: 2010 Jan 22 PMID: 20093441
Authors: Kerr, R. A.
Journal: Science

post to: CiteULike

Improving access to research.

Publication Date: 2010 Jan 22 PMID: 20093440
Authors: Courant, P. N. - O'Donnell, J. J. - Okerson, A. - Taylor, C. B.
Journal: Science

MeSH Categories: *Access to Information, Financing, Government, Policy Making, Publishing, *Research, *Research Support as Topic, United States

post to: CiteULike

Climate-Modulated Channel Incision and Rupture History of the San Andreas Fault in the Carrizo Plain.

Publication Date: 2010 Jan 21 PMID: 20093439
Authors: Ludwig, L. G. - Akciz, S. O. - Noriega, G. R. - Zielke, O. - Arrowsmith, J. R.
Journal: Science

The spatial and temporal distribution of fault slip is a critical parameter in earthquake source models. Previous geomorphic and geologic studies of channel offset along the Carrizo section of the south-central San Andreas Fault assumed that channels form more frequently than earthquakes occur and suggested that repeated large-slip earthquakes similar to the 1857 Fort Tejon earthquake illustrate typical fault behavior. Here, we show that offset channels in the Carrizo Plain incised less frequently than they were offset by earthquakes. Channels have been offset by successive earthquakes with variable slip since ~1400. This nonuniform slip history reveals a more complex rupture history than previously assumed for the structurally simplest section of the San Andreas Fault.

post to: CiteULike

The Lmo2 Oncogene Initiates Leukemia in Mice by Inducing Thymocyte Self-Renewal.

Publication Date: 2010 Jan 21 PMID: 20093438
Authors: McCormack, M. P. - Young, L. F. - Vasudevan, S. - de Graaf, C. A. - Codrington, R. - Rabbitts, T. H. - Jane, S. M. - Curtis, D. J.
Journal: Science

The LMO2 oncogene causes a subset of human T cell acute lymphoblastic leukemias (T-ALL), including four cases that arose as adverse events in gene therapy trials. To investigate the cellular origin of LMO2-induced leukemia, we used cell fate mapping to study mice in which the Lmo2 gene was constitutively expressed in the thymus. Lmo2 induced self-renewal of committed T cells in the mice more than 8 months prior to the development of overt T-ALL. These self-renewing cells retained the capacity for T cell differentiation but expressed several genes typical of hematopoietic stem cells (HSCs), suggesting that Lmo2 might reactivate an HSC-specific transcriptional program. Forced expression of one such gene, Hhex, was sufficient to initiate self-renewal of thymocytes in vivo. Thus, Lmo2 promotes the self-renewal of preleukemic thymocytes, providing a mechanism by which committed T cells can then accumulate additional genetic mutations required for leukemic transformation.

post to: CiteULike

Repulsion of Superinfecting Virions: A Mechanism for Rapid Virus Spread.

Publication Date: 2010 Jan 21 PMID: 20093437
Authors: Doceul, V. - Hollinshead, M. - van der Linden, L. - Smith, G. L.
Journal: Science

Viruses are thought to spread across susceptible cells by an iterative process of infection, replication, and release, so the rate of spread is limited by replication kinetics. Here, we show that vaccinia virus spreads across 1 cell every 75 min, fourfold faster than its replication cycle would permit. To explain this phenomenon, we found that newly infected cells express two surface proteins that mark cells as infected and, via exploitation of cellular machinery, induce repulsion of superinfecting virions away towards uninfected cells. Mechanistically, early expression of proteins A33 and A36 was critical for virion repulsion and rapid spread, and cells expressing these proteins repelled exogenous virions rapidly. Additional spreading mechanism(s) may exist for other viruses that also spread faster than predicted by replication kinetics.

post to: CiteULike

Slip in the 1857 and Earlier Large Earthquakes Along the Carrizo Plain, San Andreas Fault.

Publication Date: 2010 Jan 21 PMID: 20093436
Authors: Zielke, O. - Arrowsmith, J. R. - Ludwig, L. G. - Akciz, S. O.
Journal: Science

The M(w)7.9 Fort Tejon earthquake of 1857, with a ~350-km-long surface rupture, was the most recent major earthquake along the south-central San Andreas Fault, California. Based on previous measurements of its surface slip distribution, rupture along the ~60-km-long Carrizo segment was thought to control the recurrence of 1857-like earthquakes. New high-resolution topographic data show that the average slip along the Carrizo segment during the 1857 event was 5.3 +/- 1.4 m, eliminating the core assumption for a linkage between Carrizo segment rupture and recurrence of major earthquakes along the south-central San Andreas Fault. Earthquake slip along the Carrizo segment may recur in earthquake clusters with cumulative slip of ~5 m.

post to: CiteULike

Zebrafish behavioral profiling links drugs to biological targets and rest/wake regulation.

Publication Date: 2010 Jan 15 PMID: 20075256
Authors: Rihel, J. - Prober, D. A. - Arvanites, A. - Lam, K. - Zimmerman, S. - Jang, S. - Haggarty, S. J. - Kokel, D. - Rubin, L. L. - Peterson, R. T. - Schier, A. F.
Journal: Science

A major obstacle for the discovery of psychoactive drugs is the inability to predict how small molecules will alter complex behaviors. We report the development and application of a high-throughput, quantitative screen for drugs that alter the behavior of larval zebrafish. We found that the multidimensional nature of observed phenotypes enabled the hierarchical clustering of molecules according to shared behaviors. Behavioral profiling revealed conserved functions of psychotropic molecules and predicted the mechanisms of action of poorly characterized compounds. In addition, behavioral profiling implicated new factors such as ether-a-go-go-related gene (ERG) potassium channels and immunomodulators in the control of rest and locomotor activity. These results demonstrate the power of high-throughput behavioral profiling in zebrafish to discover and characterize psychotropic drugs and to dissect the pharmacology of complex behaviors.

MeSH Categories: Algorithms, Animals, Anti-Inflammatory Agents/pharmacology, Behavior, Animal/*drug effects, Calcium Channel Blockers/pharmacology, Calcium Channels, L-Type/metabolism, Cluster Analysis, Cytokines/metabolism, Drug Discovery/*methods, Ether-A-Go-Go Potassium Channels/antagonists & inhibitors/physiology, *High-Throughput Screening Assays, Larva/drug effects/physiology, Motor Activity/*drug effects, Potassium Channel Blockers/pharmacology, Psychotropic Drugs/*pharmacology, Rest, Signal Transduction, Sleep/drug effects, Small Molecule Libraries, Wakefulness/*drug effects, Zebrafish/growth & development/*physiology, Zebrafish Proteins/metabolism

post to: CiteULike

Functional and evolutionary insights from the genomes of three parasitoid Nasonia species.

Publication Date: 2010 Jan 15 PMID: 20075255
Authors: Werren, J. H. - Richards, S. - Desjardins, C. A. - Niehuis, O. - Gadau, J. - Colbourne, J. K. - Beukeboom, L. W. - Desplan, C. - Elsik, C. G. - Grimmelikhuijzen, C. J. - Kitts, P. - Lynch, J. A. - Murphy, T. - Oliveira, D. C. - Smith, C. D. - van de Zande, L. - Worley, K. C. - Zdobnov, E. M. - Aerts, M. - Albert, S. - Anaya, V. H. - Anzola, J. M. - Barchuk, A. R. - Behura, S. K. - Bera, A. N. - Berenbaum, M. R. - Bertossa, R. C. - Bitondi, M. M. - Bordenstein, S. R. - Bork, P. - Bornberg-Bauer, E. - Brunain, M. - Cazzamali, G. - Chaboub, L. - Chacko, J. - Chavez, D. - Childers, C. P. - Choi, J. H. - Clark, M. E. - Claudianos, C. - Clinton, R. A. - Cree, A. G. - Cristino, A. S. - Dang, P. M. - Darby, A. C. - de Graaf, D. C. - Devreese, B. - Dinh, H. H. - Edwards, R. - Elango, N. - Elhaik, E. - Ermolaeva, O. - Evans, J. D. - Foret, S. - Fowler, G. R. - Gerlach, D. - Gibson, J. D. - Gilbert, D. G. - Graur, D. - Grunder, S. - Hagen, D. E. - Han, Y. - Hauser, F. - Hultmark, D. - Hunter, H. C. 4th - Hurst, G. D. - Jhangian, S. N. - Jiang, H. - Johnson, R. M. - Jones, A. K. - Junier, T. - Kadowaki, T. - Kamping, A. - Kapustin, Y. - Kechavarzi, B. - Kim, J. - Kim, J. - Kiryutin, B. - Koevoets, T. - Kovar, C. L. - Kriventseva, E. V. - Kucharski, R. - Lee, H. - Lee, S. L. - Lees, K. - Lewis, L. R. - Loehlin, D. W. - Logsdon, J. M. Jr - Lopez, J. A. - Lozado, R. J. - Maglott, D. - Maleszka, R. - Mayampurath, A. - Mazur, D. J. - McClure, M. A. - Moore, A. D. - Morgan, M. B. - Muller, J. - Munoz-Torres, M. C. - Muzny, D. M. - Nazareth, L. V. - Neupert, S. - Nguyen, N. B. - Nunes, F. M. - Oakeshott, J. G. - Okwuonu, G. O. - Pannebakker, B. A. - Pejaver, V. R. - Peng, Z. - Pratt, S. C. - Predel, R. - Pu, L. L. - Ranson, H. - Raychoudhury, R. - Rechtsteiner, A. - Reese, J. T. - Reid, J. G. - Riddle, M. - Robertson, H. M. - Romero-Severson, J. - Rosenberg, M. - Sackton, T. B. - Sattelle, D. B. - Schluns, H. - Schmitt, T. - Schneider, M. - Schuler, A. - Schurko, A. M. - Shuker, D. M. - Simoes, Z. L. - Sinha, S. - Smith, Z. - Solovyev, V. - Souvorov, A. - Springauf, A. - Stafflinger, E. - Stage, D. E. - Stanke, M. - Tanaka, Y. - Telschow, A. - Trent, C. - Vattathil, S. - Verhulst, E. C. - Viljakainen, L. - Wanner, K. W. - Waterhouse, R. M. - Whitfield, J. B. - Wilkes, T. E. - Williamson, M. - Willis, J. H. - Wolschin, F. - Wyder, S. - Yamada, T. - Yi, S. V. - Zecher, C. N. - Zhang, L. - Gibbs, R. A.
Journal: Science

We report here genome sequences and comparative analyses of three closely related parasitoid wasps: Nasonia vitripennis, N. giraulti, and N. longicornis. Parasitoids are important regulators of arthropod populations, including major agricultural pests and disease vectors, and Nasonia is an emerging genetic model, particularly for evolutionary and developmental genetics. Key findings include the identification of a functional DNA methylation tool kit; hymenopteran-specific genes including diverse venoms; lateral gene transfers among Pox viruses, Wolbachia, and Nasonia; and the rapid evolution of genes involved in nuclear-mitochondrial interactions that are implicated in speciation. Newly developed genome resources advance Nasonia for genetic research, accelerate mapping and cloning of quantitative trait loci, and will ultimately provide tools and knowledge for further increasing the utility of parasitoids as pest insect-control agents.

MeSH Categories: Animals, Arthropods/parasitology, DNA Methylation, DNA Transposable Elements, *Evolution, Female, Gene Transfer, Horizontal, Genes, Insect, Genetic Speciation, Genetic Variation, *Genome, Insect, Host-Parasite Interactions, Insect Proteins/genetics/metabolism, Insect Viruses/genetics, Insects/genetics, Male, Molecular Sequence Data, Quantitative Trait Loci, Recombination, Genetic, Sequence Analysis, DNA, Wasp Venoms/chemistry/toxicity, Wasps/*genetics/physiology, Wolbachia/genetics

post to: CiteULike

G protein subunit Galpha13 binds to integrin alphaIIbbeta3 and mediates integrin "outside-in" signaling.

Publication Date: 2010 Jan 15 PMID: 20075254
Authors: Gong, H. - Shen, B. - Flevaris, P. - Chow, C. - Lam, S. C. - Voyno-Yasenetskaya, T. A. - Kozasa, T. - Du, X.
Journal: Science

Integrins mediate cell adhesion to the extracellular matrix and transmit signals within the cell that stimulate cell spreading, retraction, migration, and proliferation. The mechanism of integrin outside-in signaling has been unclear. We found that the heterotrimeric guanine nucleotide-binding protein (G protein) Galpha13 directly bound to the integrin beta3 cytoplasmic domain and that Galpha13-integrin interaction was promoted by ligand binding to the integrin alphaIIbbeta3 and by guanosine triphosphate (GTP) loading of Galpha13. Interference of Galpha13 expression or a myristoylated fragment of Galpha13 that inhibited interaction of alphaIIbbeta3 with Galpha13 diminished activation of protein kinase c-Src and stimulated the small guanosine triphosphatase RhoA, consequently inhibiting cell spreading and accelerating cell retraction. We conclude that integrins are noncanonical Galpha13-coupled receptors that provide a mechanism for dynamic regulation of RhoA.

MeSH Categories: Animals, Binding Sites, Blood Platelets/*physiology, Clot Retraction, Fibrinogen/metabolism, GTP-Binding Protein alpha Subunits, G12-G13/genetics/*metabolism, Humans, Integrin beta3/*metabolism, Ligands, Mice, Mice, Inbred C57BL, Phosphorylation, Platelet Adhesiveness, Platelet Glycoprotein GPIIb-IIIa Complex/*metabolism, Protein Binding, Protein Structure, Tertiary, Proto-Oncogene Proteins pp60(c-src)/metabolism, RNA, Small Interfering, Recombinant Fusion Proteins/metabolism, *Signal Transduction, rhoA GTP-Binding Protein/antagonists & inhibitors/metabolism

post to: CiteULike

Unidirectional airflow in the lungs of alligators.

Publication Date: 2010 Jan 15 PMID: 20075253
Authors: Farmer, C. G. - Sanders, K.
Journal: Science

The lungs of birds move air in only one direction during both inspiration and expiration through most of the tubular gas-exchanging bronchi (parabronchi), whereas in the lungs of mammals and presumably other vertebrates, air moves tidally into and out of terminal gas-exchange structures, which are cul-de-sacs. Unidirectional flow purportedly depends on bellowslike ventilation by air sacs and may have evolved to meet the high aerobic demands of sustained flight. Here, we show that air flows unidirectionally through parabronchi in the lungs of the American alligator, an amphibious ectotherm without air sacs, which suggests that this pattern dates back to the basal archosaurs of the Triassic and may have been present in their nondinosaur descendants (phytosaurs, aetosaurs, rauisuchians, crocodylomorphs, and pterosaurs) as well as in dinosaurs.

MeSH Categories: Alligators and Crocodiles/anatomy & histology/*physiology, Animals, Bronchi/anatomy & histology/*physiology, Dinosaurs/physiology, Evolution, Lung/anatomy & histology/*physiology, *Pulmonary Ventilation, Respiration

post to: CiteULike

The genetic map of Artemisia annua L. identifies loci affecting yield of the antimalarial drug artemisinin.

Publication Date: 2010 Jan 15 PMID: 20075252
Authors: Graham, I. A. - Besser, K. - Blumer, S. - Branigan, C. A. - Czechowski, T. - Elias, L. - Guterman, I. - Harvey, D. - Isaac, P. G. - Khan, A. M. - Larson, T. R. - Li, Y. - Pawson, T. - Penfield, T. - Rae, A. M. - Rathbone, D. A. - Reid, S. - Ross, J. - Smallwood, M. F. - Segura, V. - Townsend, T. - Vyas, D. - Winzer, T. - Bowles, D.
Journal: Science

Artemisinin is a plant natural product produced by Artemisia annua and the active ingredient in the most effective treatment for malaria. Efforts to eradicate malaria are increasing demand for an affordable, high-quality, robust supply of artemisinin. We performed deep sequencing on the transcriptome of A. annua to identify genes and markers for fast-track breeding. Extensive genetic variation enabled us to build a detailed genetic map with nine linkage groups. Replicated field trials resulted in a quantitative trait loci (QTL) map that accounts for a significant amount of the variation in key traits controlling artemisinin yield. Enrichment for positive QTLs in parents of new high-yielding hybrids confirms that the knowledge and tools to convert A. annua into a robust crop are now available.

MeSH Categories: Antimalarials/*metabolism, Artemisia/*genetics/*metabolism, Artemisinins/*metabolism, *Chromosome Mapping, Crosses, Genetic, DNA, Complementary, Gene Expression Profiling, *Genes, Plant, Genetic Association Studies, Humans, Malaria/drug therapy, Mutation, Phenotype, Polymorphism, Single Nucleotide, *Quantitative Trait Loci, Sequence Analysis, DNA

post to: CiteULike

Lower predation risk for migratory birds at high latitudes.

Publication Date: 2010 Jan 15 PMID: 20075251
Authors: McKinnon, L. - Smith, P. A. - Nol, E. - Martin, J. L. - Doyle, F. I. - Abraham, K. F. - Gilchrist, H. G. - Morrison, R. I. - Bety, J.
Journal: Science

Quantifying the costs and benefits of migration distance is critical to understanding the evolution of long-distance migration. In migratory birds, life history theory predicts that the potential survival costs of migrating longer distances should be balanced by benefits to lifetime reproductive success, yet quantification of these reproductive benefits in a controlled manner along a large geographical gradient is challenging. We measured a controlled effect of predation risk along a 3350-kilometer south-north gradient in the Arctic and found that nest predation risk declined more than twofold along the latitudinal gradient. These results provide evidence that birds migrating farther north may acquire reproductive benefits in the form of lower nest predation risk.

MeSH Categories: *Animal Migration, Animals, Arctic Regions, Birds/*physiology, *Ecosystem, Geography, *Nesting Behavior, *Predatory Behavior, *Reproduction, Risk

post to: CiteULike

Large-scale controls of methanogenesis inferred from methane and gravity spaceborne data.

Publication Date: 2010 Jan 15 PMID: 20075250
Authors: Bloom, A. A. - Palmer, P. I. - Fraser, A. - Reay, D. S. - Frankenberg, C.
Journal: Science

Wetlands are the largest individual source of methane (CH4), but the magnitude and distribution of this source are poorly understood on continental scales. We isolated the wetland and rice paddy contributions to spaceborne CH4 measurements over 2003-2005 using satellite observations of gravity anomalies, a proxy for water-table depth Gamma, and surface temperature analyses TS. We find that tropical and higher-latitude CH4 variations are largely described by Gamma and TS variations, respectively. Our work suggests that tropical wetlands contribute 52 to 58% of global emissions, with the remainder coming from the extra-tropics, 2% of which is from Arctic latitudes. We estimate a 7% rise in wetland CH4 emissions over 2003-2007, due to warming of mid-latitude and Arctic wetland regions, which we find is consistent with recent changes in atmospheric CH4.

MeSH Categories: Archaea/metabolism, Atmosphere/*chemistry, *Crops, Agricultural/growth & development, Geography, Gravitation, Methane/*analysis/biosynthesis, *Oryza sativa/growth & development, Seasons, Spacecraft, Temperature, Tropical Climate, *Wetlands

post to: CiteULike

Nanoporous gold catalysts for selective gas-phase oxidative coupling of methanol at low temperature.

Publication Date: 2010 Jan 15 PMID: 20075249
Authors: Wittstock, A. - Zielasek, V. - Biener, J. - Friend, C. M. - Baumer, M.
Journal: Science

Gold (Au) is an interesting catalytic material because of its ability to catalyze reactions, such as partial oxidations, with high selectivities at low temperatures; but limitations arise from the low O2 dissociation probability on Au. This problem can be overcome by using Au nanoparticles supported on suitable oxides which, however, are prone to sintering. Nanoporous Au, prepared by the dealloying of AuAg alloys, is a new catalyst with a stable structure that is active without any support. It catalyzes the selective oxidative coupling of methanol to methyl formate with selectivities above 97% and high turnover frequencies at temperatures below 80 degrees C. Because the overall catalytic characteristics of nanoporous Au are in agreement with studies on Au single crystals, we deduced that the selective surface chemistry of Au is unaltered but that O2 can be readily activated with this material. Residual silver is shown to regulate the availability of reactive oxygen.

post to: CiteULike

Electrocatalytic CO2 conversion to oxalate by a copper complex.

Publication Date: 2010 Jan 15 PMID: 20075248
Authors: Angamuthu, R. - Byers, P. - Lutz, M. - Spek, A. L. - Bouwman, E.
Journal: Science

Global warming concern has dramatically increased interest in using CO2 as a feedstock for preparation of value-added compounds, thereby helping to reduce its atmospheric concentration. Here, we describe a dinuclear copper(I) complex that is oxidized in air by CO2 rather than O2; the product is a tetranuclear copper(II) complex containing two bridging CO2-derived oxalate groups. Treatment of the copper(II) oxalate complex in acetonitrile with a soluble lithium salt results in quantitative precipitation of lithium oxalate. The copper(II) complex can then be nearly quantitatively electrochemically reduced at a relatively accessible potential, regenerating the initial dinuclear copper(I) compound. Preliminary results demonstrate six turnovers (producing 12 equivalents of oxalate) during 7 hours of catalysis at an applied potential of -0.03 volts versus the normal hydrogen electrode.

post to: CiteULike

How the shape of an H-bonded network controls proton-coupled water activation in HONO formation.

Publication Date: 2010 Jan 15 PMID: 20075247
Authors: Relph, R. A. - Guasco, T. L. - Elliott, B. M. - Kamrath, M. Z. - McCoy, A. B. - Steele, R. P. - Schofield, D. P. - Jordan, K. D. - Viggiano, A. A. - Ferguson, E. E. - Johnson, M. A.
Journal: Science

Many chemical reactions in atmospheric aerosols and bulk aqueous environments are influenced by the surrounding solvation shell, but the precise molecular interactions underlying such effects have rarely been elucidated. We exploited recent advances in isomer-specific cluster vibrational spectroscopy to explore the fundamental relation between the hydrogen (H)-bonding arrangement of a set of ion-solvating water molecules and the chemical activity of this ensemble. We find that the extent to which the nitrosonium ion (NO+)and water form nitrous acid (HONO) and a hydrated proton cluster in the critical trihydrate depends sensitively on the geometrical arrangement of the water molecules in the network. Theoretical analysis of these data details the role of the water network in promoting charge delocalization.

post to: CiteULike

Hungry codons promote frameshifting in human mitochondrial ribosomes.

Publication Date: 2010 Jan 15 PMID: 20075246
Authors: Temperley, R. - Richter, R. - Dennerlein, S. - Lightowlers, R. N. - Chrzanowska-Lightowlers, Z. M.
Journal: Science

Human mitochondria are not strict adherents to the universal genetic code, with modifications that include the apparent recoding of two arginine triplets to termination signals. This use of both AGA and AGG occurs rarely in other mammals, and this putative change has long posed a challenging conundrum. A -1 mitoribosome frameshift upstream of the rare codons would necessitate recognition of only the conventional UAA and UAG termination codons. By using a sequence-specific endoribonuclease, we show that the rare arginine codons, presumably in association with other cis elements, promote frameshifting in human mitoribosomes.

MeSH Categories: 3' Untranslated Regions, Arginine/genetics, Codon, Terminator/*genetics, Endoribonucleases/metabolism, *Frameshifting, Ribosomal, Genes, Mitochondrial, Humans, Mitochondria/*genetics/ultrastructure, Mitochondrial Proteins/genetics/metabolism, Open Reading Frames, Peptide Termination Factors/genetics/metabolism, RNA/genetics/*metabolism, RNA, Messenger/genetics/*metabolism, Ribosomes/*genetics/metabolism

post to: CiteULike

The NLRP3 inflammasome: a sensor for metabolic danger?

Publication Date: 2010 Jan 15 PMID: 20075245
Authors: Schroder, K. - Zhou, R. - Tschopp, J.
Journal: Science

Interleukin-1beta (IL-1beta), reactive oxygen species (ROS), and thioredoxin-interacting protein (TXNIP) are all implicated in the pathogenesis of type 2 diabetes mellitus (T2DM). Here we review mechanisms directing IL-1beta production and its pathogenic role in islet dysfunction during chronic hyperglycemia. In doing so, we integrate previously disparate disease-driving mechanisms for IL-1beta, ROS, and TXNIP in T2DM into one unifying model in which the NLRP3 inflammasome plays a central role. The NLRP3 inflammasome also drives IL-1beta maturation and secretion in another disease of metabolic dysregulation, gout. Thus, we propose that the NLRP3 inflammasome contributes to the pathogenesis of T2DM and gout by functioning as a sensor for metabolic stress.

MeSH Categories: Animals, Carrier Proteins/*metabolism, Diabetes Mellitus, Type 2/immunology/*metabolism/physiopathology, Gout/immunology/metabolism, Humans, *Inflammation, Insulin-Secreting Cells/physiology, Interleukin-1beta/metabolism/secretion, Multiprotein Complexes/*metabolism, Reactive Oxygen Species/metabolism, *Stress, Physiological

post to: CiteULike

Regulation of adaptive immunity by the innate immune system.

Publication Date: 2010 Jan 15 PMID: 20075244
Authors: Iwasaki, A. - Medzhitov, R.
Journal: Science

Twenty years after the proposal that pattern recognition receptors detect invasion by microbial pathogens, the field of immunology has witnessed several discoveries that have elucidated receptors and signaling pathways of microbial recognition systems and how they control the generation of T and B lymphocyte-mediated immune responses. However, there are still many fundamental questions that remain poorly understood, even though sometimes the answers are assumed to be known. Here, we discuss some of these questions, including the mechanisms by which pathogen-specific innate immune recognition activates antigen-specific adaptive immune responses and the roles of different types of innate immune recognition in host defense from infection and injury.

MeSH Categories: *Adaptive Immunity, Animals, Antigen-Presenting Cells/immunology, Bacterial Infections/*immunology, Humans, *Immunity, Innate, Ligands, Receptors, Pattern Recognition/immunology/*metabolism, Signal Transduction, Toll-Like Receptors/immunology/metabolism, Virus Diseases/*immunology

post to: CiteULike

How the noninflammasome NLRs function in the innate immune system.

Publication Date: 2010 Jan 15 PMID: 20075243
Authors: Ting, J. P. - Duncan, J. A. - Lei, Y.
Journal: Science

NLR (nucleotide-binding domain, leucine-rich repeat-containing) proteins have rapidly emerged as central regulators of immunity and inflammation with demonstrated relevance to human diseases. Much attention has focused on the ability of several NLRs to activate the inflammasome complex and drive proteolytic processing of inflammatory cytokines; however, NLRs also regulate important inflammasome-independent functions in the immune system. We discuss several of these functions, including the regulation of canonical and noncanonical NF-kappaB activation, mitogen-activated protein kinase activation, cytokine and chemokine production, antimicrobial reactive oxygen species production, type I interferon production, and ribonuclease L activity. We also explore the mechanistic basis of these functions and describe current challenges in the field.

MeSH Categories: Animals, Cytokines/metabolism, Endoribonucleases/metabolism, Humans, *Immunity, Innate, Inflammation, Interferon Type I/metabolism, Intracellular Signaling Peptides and Proteins/chemistry/*metabolism, Mitochondrial Proteins/metabolism, Mitogen-Activated Protein Kinases/metabolism, NF-kappa B/metabolism, Nod1 Signaling Adaptor Protein/metabolism, Nod2 Signaling Adaptor Protein/metabolism, Protein Interaction Domains and Motifs, Receptors, Pattern Recognition/chemistry/*metabolism, *Signal Transduction

post to: CiteULike

RIGorous detection: exposing virus through RNA sensing.

Publication Date: 2010 Jan 15 PMID: 20075242
Authors: Rehwinkel, J. - Reis e Sousa, C.
Journal: Science

Virus infection in mammals elicits a variety of defense responses that are initiated by signals from virus-sensing receptors expressed by the host. These receptors include the ubiquitously expressed RIG-I-like receptor (RLR) family of RNA helicases. RLRs are cytoplasmic proteins that act in cell-intrinsic antiviral defense by recognizing RNAs indicative of virus presence. Here, we highlight recent progress in understanding how RLRs discriminate between the RNA content of healthy versus virus-infected cells, functioning as accurate sensors of virus invasion.

MeSH Categories: Animals, Base Pairing, DEAD-box RNA Helicases/chemistry/immunology/*metabolism, Genome, Viral, Humans, *Immunity, Innate, Interferons/biosynthesis, Nucleic Acid Conformation, Protein Structure, Tertiary, RNA Virus Infections/*immunology, RNA Viruses/genetics/*immunology, RNA, Double-Stranded/immunology/metabolism, RNA, Viral/chemistry/*immunology/*metabolism, Receptors, Pattern Recognition/chemistry/immunology/*metabolism, Signal Transduction, Viral Proteins/immunology/metabolism

post to: CiteULike

Innate immunity. Recognizing the first responders. Introduction.

Publication Date: 2010 Jan 15 PMID: 20075241
Authors: Mueller, K. L.
Journal: Science

MeSH Categories: Adaptive Immunity, Animals, Humans, *Immunity, Innate, Lymphocyte Activation, Receptors, Pattern Recognition/physiology

post to: CiteULike

Retrospective. Paul A. Samuelson (1915-2009).

Publication Date: 2010 Jan 15 PMID: 20075240
Authors: Solow, R. M.
Journal: Science

post to: CiteULike

Chemistry. Ion chemistry mediated by water networks.

Publication Date: 2010 Jan 15 PMID: 20075239
Authors: Siefermann, K. R. - Abel, B.
Journal: Science

post to: CiteULike

Plant science. The botanical solution for malaria.

Publication Date: 2010 Jan 15 PMID: 20075238
Authors: Milhous, W. K. - Weina, P. J.
Journal: Science

MeSH Categories: Animals, Antimalarials/*metabolism/therapeutic use/toxicity, Artemisia annua/*genetics/*metabolism, Artemisinins/*metabolism/therapeutic use/toxicity, *Chromosome Mapping, Crosses, Genetic, Gene Expression Profiling, Humans, Malaria/*drug therapy, *Quantitative Trait Loci, Sequence Analysis, DNA

post to: CiteULike

Chemistry. Green gold catalysis.

Publication Date: 2010 Jan 15 PMID: 20075237
Authors: Christensen, C. H. - Norskov, J. K.
Journal: Science

post to: CiteULike

Ecology. Explaining bird migration.

Publication Date: 2010 Jan 15 PMID: 20075236
Authors: Gilg, O. - Yoccoz, N. G.
Journal: Science

MeSH Categories: *Animal Migration, Animals, Arctic Regions, Birds/*physiology, *Ecosystem, *Nesting Behavior, Population Density, Population Dynamics, *Predatory Behavior

post to: CiteULike

Biochemistry. CO2mmon sense.

Publication Date: 2010 Jan 15 PMID: 20075235
Authors: Frommer, W. B.
Journal: Science

MeSH Categories: Animals, Bicarbonates/metabolism, Carbon Dioxide/*analysis/metabolism, Carbonic Anhydrases/genetics/*metabolism, Evolution, Molecular, Humans, Hydrogen-Ion Concentration, Plant Stomata/metabolism, Plants/enzymology/*metabolism, Taste, Taste Buds/metabolism

post to: CiteULike

Health care policy. Reforming off-label promotion to enhance orphan disease treatment.

Publication Date: 2010 Jan 15 PMID: 20075234
Authors: Liang, B. A. - Mackey, T.
Journal: Science

MeSH Categories: Drug Approval, *Health Policy, Humans, Legislation, Drug, *Off-Label Use/legislation & jurisprudence, Orphan Drug Production/legislation & jurisprudence, Product Surveillance, Postmarketing, Rare Diseases/*drug therapy, United States, United States Food and Drug Administration

post to: CiteULike

The potential of nutritional therapy.

Publication Date: 2010 Jan 15 PMID: 20075232
Authors: Gardner, A. - Kaplan, B. J. - Rucklidge, J. J. - Jonsson, B. H. - Humble, M. B.
Journal: Science

MeSH Categories: Diet, *Dietary Supplements, Humans, Mental Disorders/*diet therapy, Mental Health, Micronutrients/*administration & dosage, Prisoners, Violence/prevention & control

post to: CiteULike

Emissions omissions.

Publication Date: 2010 Jan 15 PMID: 20075231
Authors: Wallington, T. J. - Anderson, J. E. - Mueller, S. A. - Winkler, S. - Ginder, J. M.
Journal: Science

post to: CiteULike

Infectious diseases. Questions abound in Q-fever explosion in the Netherlands.

Publication Date: 2010 Jan 15 PMID: 20075230
Authors: Enserink, M.
Journal: Science

MeSH Categories: Abortion, Veterinary/microbiology/prevention & control, Animal Husbandry, Animals, Bacterial Vaccines, Bioterrorism, Coxiella burnetii/immunology/pathogenicity, *Disease Outbreaks/prevention & control/veterinary, Female, *Goat Diseases, Goats, Humans, Netherlands/epidemiology, Pregnancy, Q Fever/*epidemiology/prevention & control/transmission/veterinary

post to: CiteULike

Infectious diseases. Humans, animals--it's one health. Or is it?

Publication Date: 2010 Jan 15 PMID: 20075229
Authors: Enserink, M.
Journal: Science

MeSH Categories: Animals, *Disease Outbreaks/veterinary, Humans, Netherlands/epidemiology, *Public Health, Q Fever/*epidemiology/transmission/*veterinary, *Veterinary Medicine

post to: CiteULike

Fisheries. The secret lives of ocean fish.

Publication Date: 2010 Jan 15 PMID: 20075228
Authors: Kean, S.
Journal: Science

MeSH Categories: Animals, *Ecosystem, *Gadus morhua, Oceans and Seas, Population Dynamics, *Salmon, *Seawater, Water Movements

post to: CiteULike

Fisheries. Fishing for gold in The Last Frontier State.

Publication Date: 2010 Jan 15 PMID: 20075227
Authors: Kean, S.
Journal: Science

MeSH Categories: Alaska, Animals, Copper, *Ecosystem, Environment, *Fisheries, Gold, *Mining, Population Dynamics, Rivers, *Salmon

post to: CiteULike

Entomology. The little wasp that could.

Publication Date: 2010 Jan 15 PMID: 20075226
Authors: Pennisi, E.
Journal: Science

MeSH Categories: Animals, Female, Genes, Insect, *Genome, Insect, Insects/parasitology, Lepidoptera/parasitology, Male, Pest Control, Biological, Research, Sequence Analysis, DNA, Wasps/classification/*genetics/microbiology/physiology

post to: CiteULike

Publishing. White House mulls plan to broaden access to published papers.

Publication Date: 2010 Jan 15 PMID: 20075225
Authors: Kaiser, J.
Journal: Science

MeSH Categories: *Access to Information, Costs and Cost Analysis, *Financing, Government, National Institutes of Health (U.S.), Periodicals as Topic/economics, *Publishing/economics, *Research Support as Topic, United States

post to: CiteULike

Astronomy. Oldest galaxies show stars came together in a hurry.

Publication Date: 2010 Jan 15 PMID: 20075223
Authors: Bhattacharjee, Y.
Journal: Science

post to: CiteULike

Astronomy. Inventory asks: where is all the non-dark matter hiding?

Publication Date: 2010 Jan 15 PMID: 20075222
Authors: Bhattacharjee, Y.
Journal: Science

post to: CiteULike

Chemistry. Catalyst offers new hope for capturing CO2 on the cheap.

Publication Date: 2010 Jan 15 PMID: 20075221
Authors: Service, R. F.
Journal: Science

post to: CiteULike

Academic facilities. NIST grants help schools build for tomorrow's research.

Publication Date: 2010 Jan 15 PMID: 20075219
Authors: Mervis, J.
Journal: Science

post to: CiteULike

Archaeology. Neandertal jewelry shows their symbolic smarts.

Publication Date: 2010 Jan 15 PMID: 20075218
Authors: Balter, M.
Journal: Science

MeSH Categories: Animals, Archaeology, *Hominidae, Humans, *Jewelry, Social Behavior, Spain, *Symbolism

post to: CiteULike

Virology. An indefatigable debate over chronic fatigue syndrome.

Publication Date: 2010 Jan 15 PMID: 20075217
Authors: Kean, S.
Journal: Science

MeSH Categories: Adult, Aged, Fatigue Syndrome, Chronic/etiology/*virology, Gammaretrovirus/genetics/*isolation & purification, Humans, Middle Aged, Polymerase Chain Reaction, Young Adult

post to: CiteULike

New approaches in immunotherapy.

Publication Date: 2010 Jan 15 PMID: 20075216
Authors: Thomas, P. G. - Doherty, P. C.
Journal: Science

MeSH Categories: Humans, *Immunity, Innate, Immunotherapy, Inflammation, Receptors, Pattern Recognition/*physiology, Signal Transduction, Toll-Like Receptors/physiology

post to: CiteULike

A Genetic Variant BDNF Polymorphism Alters Extinction Learning in Both Mouse and Human.

Publication Date: 2010 Jan 14 PMID: 20075215
Authors: Soliman, F. - Glatt, C. E. - Bath, K. G. - Levita, L. - Jones, R. M. - Pattwell, S. S. - Jing, D. - Tottenham, N. - Amso, D. - Somerville, L. - Voss, H. U. - Glover, G. - Ballon, D. J. - Liston, C. - Teslovich, T. - Van Kempen, T. - Lee, F. S. - Casey, B. J.
Journal: Science

Mouse models are useful for studying genes involved in behavior, but whether they are relevant for human behavior is unclear. Here, we identified parallel phenotypes in mice and humans resulting from a common single-nucleotide polymorphism in the brain-derived neurotrophic factor (BDNF) gene, which is involved in anxiety-related behavior. An inbred genetic knock-in mouse strain expressing the variant BDNF recapitulated the phenotypic effects of the human polymorphism. Both were impaired in extinguishing a conditioned fear response, which was paralleled by atypical frontoamygdala activity in humans. Thus, this variant BDNF allele may play a role in anxiety disorders showing impaired learning of cues that signal safety versus threat and in the efficacy of treatments that rely on extinction mechanisms, such as exposure therapy.

post to: CiteULike

Evolutionary Dynamics of Complex Networks of HIV Drug-Resistant Strains: The Case of San Francisco.

Publication Date: 2010 Feb 5 PMID: 20075214
Authors: Smith, R. J. - Okano, J. T. - Kahn, J. S. - Bodine, E. N. - Blower, S.
Journal: Science

Over the past two decades, HIV resistance to antiretroviral drugs (ARVs) has risen to high levels in the wealthier countries of the world, which are able to afford widespread treatment. We have gained insights into the evolution and transmission dynamics of ARV resistance by designing a biologically complex multistrain network model. With this model, we traced the evolutionary history of ARV resistance in San Francisco and predict its future dynamics. By using classification and regression trees, we identified the key immunologic, virologic, and treatment factors that increase ARV resistance. Our modeling shows that 60% of the currently circulating ARV-resistant strains in San Francisco are capable of causing self-sustaining epidemics, because each individual infected with one of these strains can cause, on average, more than one new resistant infection. It is possible that a new wave of ARV-resistant strains that pose a substantial threat to global public health is emerging.

post to: CiteULike

Effect of ocean acidification on iron availability to marine phytoplankton.

Publication Date: 2010 Feb 5 PMID: 20075213
Authors: Shi, D. - Xu, Y. - Hopkinson, B. M. - Morel, F. M.
Journal: Science

The acidification caused by the dissolution of anthropogenic carbon dioxide (CO(2)) in the ocean changes the chemistry and hence the bioavailability of iron (Fe), a limiting nutrient in large oceanic regions. Here, we show that the bioavailability of dissolved Fe may decline because of ocean acidification. Acidification of media containing various Fe compounds decreases the Fe uptake rate of diatoms and coccolithophores to an extent predicted by the changes in Fe chemistry. A slower Fe uptake by a model diatom with decreasing pH is also seen in experiments with Atlantic surface water. The Fe requirement of model phytoplankton remains unchanged with increasing CO(2). The ongoing acidification of seawater is likely to increase the Fe stress of phytoplankton populations in some areas of the ocean.

post to: CiteULike

Deglacial Meltwater Pulse 1B and Younger Dryas Sea Levels Revisited with Boreholes at Tahiti.

Publication Date: 2010 Jan 14 PMID: 20075212
Authors: Bard, E. - Hamelin, B. - Delanghe-Sabatier, D.
Journal: Science

Reconstructing sea-level changes during the last deglaciation provides a way of understanding the ice dynamics that can perturb large continental ice sheets. The resolution of the few sea-level records covering the critical time interval between 14 and 9 thousand calendar years before the present (cal kyr B.P.) is still insufficient to draw conclusions about sea-level changes associated with the Younger Dryas (YD) cold event and the meltwater pulse 1B (MWP-1B). Here, we use the U-Th method to date shallow-living corals from three new cores drilled onshore in the Tahiti barrier reef. No significant discontinuity can be detected in the sea-level rise during the MWP-1B period. The new Tahiti sea-level record shows that the sea-level rise slowed down during the YD before accelerating again during the Holocene.

post to: CiteULike

Ferroelectric Control of Spin Polarization.

Publication Date: 2010 Jan 14 PMID: 20075211
Authors: Garcia, V. - Bibes, M. - Bocher, L. - Valencia, S. - Kronast, F. - Crassous, A. - Moya, X. - Enouz-Vedrenne, S. - Gloter, A. - Imhoff, D. - Deranlot, C. - Mathur, N. D. - Fusil, S. - Bouzehouane, K. - Barthelemy, A.
Journal: Science

A current drawback of spintronics is the large power that is usually required for magnetic writing, in contrast with nanoelectronics, which relies on "zero-current," gate-controlled operations. Efforts have been made to control the spin-relaxation rate, the Curie temperature or the magnetic anisotropy with a gate voltage, but these effects are usually small and volatile. Here, we use ferroelectric tunnel junctions with ferromagnetic electrodes to demonstrate local, large and nonvolatile control of carrier spin polarization by electrically switching ferroelectric polarization. Our results represent a giant type of interfacial magnetoelectric coupling and suggest a low-power approach for spin-based information control.

post to: CiteULike

Essential role of the histone methyltransferase G9a in cocaine-induced plasticity.

Publication Date: 2010 Jan 8 PMID: 20056891
Authors: Maze, I. - Covington, H. E. 3rd - Dietz, D. M. - LaPlant, Q. - Renthal, W. - Russo, S. J. - Mechanic, M. - Mouzon, E. - Neve, R. L. - Haggarty, S. J. - Ren, Y. - Sampath, S. C. - Hurd, Y. L. - Greengard, P. - Tarakhovsky, A. - Schaefer, A. - Nestler, E. J.
Journal: Science

Cocaine-induced alterations in gene expression cause changes in neuronal morphology and behavior that may underlie cocaine addiction. In mice, we identified an essential role for histone 3 lysine 9 (H3K9) dimethylation and the lysine dimethyltransferase G9a in cocaine-induced structural and behavioral plasticity. Repeated cocaine administration reduced global levels of H3K9 dimethylation in the nucleus accumbens. This reduction in histone methylation was mediated through the repression of G9a in this brain region, which was regulated by the cocaine-induced transcription factor DeltaFosB. Using conditional mutagenesis and viral-mediated gene transfer, we found that G9a down-regulation increased the dendritic spine plasticity of nucleus accumbens neurons and enhanced the preference for cocaine, thereby establishing a crucial role for histone methylation in the long-term actions of cocaine.

MeSH Categories: Animals, Behavior, Animal/*drug effects, Cocaine/*administration & dosage/pharmacology, Cocaine-Related Disorders/etiology/metabolism, Dendritic Spines/physiology, Down-Regulation, Enzyme Repression, Gene Expression Profiling, Gene Expression Regulation, Histone-Lysine N-Methyltransferase/genetics/*metabolism, Histones/*metabolism, Lysine/metabolism, Male, Methylation, Mice, Mice, Inbred C57BL, *Neuronal Plasticity, Neurons/drug effects/*metabolism, Nucleus Accumbens/cytology/drug effects/*metabolism, Oligonucleotide Array Sequence Analysis, Proto-Oncogene Proteins c-fos/genetics/metabolism, Reward, Self Administration, Transcription, Genetic

post to: CiteULike

A transient niche regulates the specification of Drosophila intestinal stem cells.

Publication Date: 2010 Jan 8 PMID: 20056890
Authors: Mathur, D. - Bost, A. - Driver, I. - Ohlstein, B.
Journal: Science

Stem cell niches are locations where stem cells reside and self-renew. Although studies have shown how niches maintain stem cell fate during tissue homeostasis, less is known about their roles in establishing stem cells. The adult Drosophila midgut is maintained by intestinal stem cells (ISCs); however, how they are established is unknown. Here, we show that an ISC progenitor generates a niche cell via Notch signaling. This niche uses the bone morphogenetic protein 2/4 homolog, decapentaplegic, to allow progenitors to divide in an undifferentiated state and subsequently breaks down and dies, resulting in the specification of ISCs in the adult midgut. Our results demonstrate a paradigm for stem cell-niche biology, where progenitors generate transient niches that determine stem cell fate and may give insights into stem cell specification in other tissues.

MeSH Categories: Adult Stem Cells/*cytology/physiology, Animals, Cell Differentiation, Cell Lineage, Cell Proliferation, Drosophila/*cytology/growth & development/metabolism, Drosophila Proteins/genetics/metabolism, Enterocytes/cytology, Epithelial Cells/*cytology, Intestines/cytology/growth & development, Larva/cytology/growth & development/metabolism, Metamorphosis, Biological, Organogenesis, Receptors, Notch/metabolism, Signal Transduction, Stem Cell Niche/*physiology

post to: CiteULike

Topology links RNA secondary structure with global conformation, dynamics, and adaptation.

Publication Date: 2010 Jan 8 PMID: 20056889
Authors: Bailor, M. H. - Sun, X. - Al-Hashimi, H. M.
Journal: Science

Thermodynamic rules that link RNA sequences to secondary structure are well established, but the link between secondary structure and three-dimensional global conformation remains poorly understood. We constructed comprehensive three-dimensional maps depicting the orientation of A-form helices across RNA junctions in the Protein Data Bank and rationalized our findings with modeling and nuclear magnetic resonance spectroscopy. We show that the secondary structures of junctions encode readily computable topological constraints that accurately predict the three-dimensional orientation of helices across all two-way junctions. Our results suggest that RNA global conformation is largely defined by topological constraints encoded at the secondary structural level and that tertiary contacts and intermolecular interactions serve to stabilize specific conformers within the topologically allowed ensemble.

MeSH Categories: Anisotropy, Base Pairing, Base Sequence, Biochemical Phenomena, Databases, Nucleic Acid, *HIV Long Terminal Repeat, HIV-1, Kanamycin/chemistry/metabolism, Ligands, Models, Molecular, Neomycin/chemistry/metabolism, Nuclear Magnetic Resonance, Biomolecular, *Nucleic Acid Conformation, RNA/*chemistry/metabolism, RNA, Viral/*chemistry/metabolism

post to: CiteULike

Reefs as cradles of evolution and sources of biodiversity in the Phanerozoic.

Publication Date: 2010 Jan 8 PMID: 20056888
Authors: Kiessling, W. - Simpson, C. - Foote, M.
Journal: Science

Large-scale biodiversity gradients among environments and habitats are usually attributed to a complex array of ecological and evolutionary factors. We tested the evolutionary component of such gradients by compiling the environments of the geologically oldest occurrences of marine genera and using sampling standardization to assess if originations tended to be clustered in particular environments. Shallow, tropical environments and carbonate substrates all tend to have harbored high origination rates. Diversity within these environments tended to be preferentially generated in reefs, probably because of their habitat complexity. Reefs were also prolific at exporting diversity to other environments, which might be a consequence of low-diversity habitats being more susceptible to invasions.

MeSH Categories: Animals, *Anthozoa, *Biodiversity, Calcium Carbonate, *Ecosystem, Environment, *Evolution, Fishes, *Fossils, Geography, *Invertebrates/classification

post to: CiteULike

E-type asteroid (2867) Steins as imaged by OSIRIS on board Rosetta.

Publication Date: 2010 Jan 8 PMID: 20056887
Authors: Keller, H. U. - Barbieri, C. - Koschny, D. - Lamy, P. - Rickman, H. - Rodrigo, R. - Sierks, H. - A'Hearn, M. F. - Angrilli, F. - Barucci, M. A. - Bertaux, J. L. - Cremonese, G. - Da Deppo, V. - Davidsson, B. - De Cecco, M. - Debei, S. - Fornasier, S. - Fulle, M. - Groussin, O. - Gutierrez, P. J. - Hviid, S. F. - Ip, W. H. - Jorda, L. - Knollenberg, J. - Kramm, J. R. - Kuhrt, E. - Kuppers, M. - Lara, L. M. - Lazzarin, M. - Lopez Moreno, J. - Marzari, F. - Michalik, H. - Naletto, G. - Sabau, L. - Thomas, N. - Wenzel, K. P. - Bertini, I. - Besse, S. - Ferri, F. - Kaasalainen, M. - Lowry, S. - Marchi, S. - Mottola, S. - Sabolo, W. - Schroder, S. E. - Spjuth, S. - Vernazza, P.
Journal: Science

The European Space Agency's Rosetta mission encountered the main-belt asteroid (2867) Steins while on its way to rendezvous with comet 67P/Churyumov-Gerasimenko. Images taken with the OSIRIS (optical, spectroscopic, and infrared remote( )imaging system) cameras on board Rosetta show that Steins is an oblate body with an effective spherical diameter of 5.3 kilometers. Its surface does not show color variations. The morphology of Steins is dominated by linear faults and a large 2.1-kilometer-diameter crater near its south pole. Crater counts reveal a distinct lack of small craters. Steins is not solid rock but a rubble pile and has a conical appearance that is probably the result of reshaping due to Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) spin-up. The OSIRIS images constitute direct evidence for the YORP effect on a main-belt asteroid.

post to: CiteULike

Energy-conversion properties of vapor-liquid-solid-grown silicon wire-array photocathodes.

Publication Date: 2010 Jan 8 PMID: 20056886
Authors: Boettcher, S. W. - Spurgeon, J. M. - Putnam, M. C. - Warren, E. L. - Turner-Evans, D. B. - Kelzenberg, M. D. - Maiolo, J. R. - Atwater, H. A. - Lewis, N. S.
Journal: Science

Silicon wire arrays, though attractive materials for use in photovoltaics and as photocathodes for hydrogen generation, have to date exhibited poor performance. Using a copper-catalyzed, vapor-liquid-solid-growth process, SiCl4 and BCl3 were used to grow ordered arrays of crystalline p-type silicon (p-Si) microwires on p+-Si(111) substrates. When these wire arrays were used as photocathodes in contact with an aqueous methyl viologen(2+/+) electrolyte, energy-conversion efficiencies of up to 3% were observed for monochromatic 808-nanometer light at fluxes comparable to solar illumination, despite an external quantum yield at short circuit of only 0.2. Internal quantum yields were at least 0.7, demonstrating that the measured photocurrents were limited by light absorption in the wire arrays, which filled only 4% of the incident optical plane in our test devices. The inherent performance of these wires thus conceptually allows the development of efficient photovoltaic and photoelectrochemical energy-conversion devices based on a radial junction platform.

post to: CiteULike

Nematic electronic structure in the "parent" state of the iron-based superconductor Ca(Fe(1-x)Co(x))2As2.

Publication Date: 2010 Jan 8 PMID: 20056885
Authors: Chuang, T. M. - Allan, M. P. - Lee, J. - Xie, Y. - Ni, N. - Bud'ko, S. L. - Boebinger, G. S. - Canfield, P. C. - Davis, J. C.
Journal: Science

The mechanism of high-temperature superconductivity in the newly discovered iron-based superconductors is unresolved. We use spectroscopic imaging-scanning tunneling microscopy to study the electronic structure of a representative compound CaFe1.94Co0.06As2 in the "parent" state from which this superconductivity emerges. Static, unidirectional electronic nanostructures of dimension eight times the inter-iron-atom distance a(Fe-Fe) and aligned along the crystal a axis are observed. In contrast, the delocalized electronic states detectable by quasiparticle interference imaging are dispersive along the b axis only and are consistent with a nematic alpha2 band with an apparent band folding having wave vector q vector congruent with +/-2pi/8a(Fe-Fe) along the a axis. All these effects rotate through 90 degrees at orthorhombic twin boundaries, indicating that they are bulk properties. As none of these phenomena are expected merely due to crystal symmetry, underdoped ferropnictides may exhibit a more complex electronic nematic state than originally expected.

post to: CiteULike

Quantum criticality in an Ising chain: experimental evidence for emergent E8 symmetry.

Publication Date: 2010 Jan 8 PMID: 20056884
Authors: Coldea, R. - Tennant, D. A. - Wheeler, E. M. - Wawrzynska, E. - Prabhakaran, D. - Telling, M. - Habicht, K. - Smeibidl, P. - Kiefer, K.
Journal: Science

Quantum phase transitions take place between distinct phases of matter at zero temperature. Near the transition point, exotic quantum symmetries can emerge that govern the excitation spectrum of the system. A symmetry described by the E8 Lie group with a spectrum of eight particles was long predicted to appear near the critical point of an Ising chain. We realize this system experimentally by using strong transverse magnetic fields to tune the quasi-one-dimensional Ising ferromagnet CoNb2O6 (cobalt niobate) through its critical point. Spin excitations are observed to change character from pairs of kinks in the ordered phase to spin-flips in the paramagnetic phase. Just below the critical field, the spin dynamics shows a fine structure with two sharp modes at low energies, in a ratio that approaches the golden mean predicted for the first two meson particles of the E8 spectrum. Our results demonstrate the power of symmetry to describe complex quantum behaviors.

post to: CiteULike

Punishers benefit from third-party punishment in fish.

Publication Date: 2010 Jan 8 PMID: 20056883
Authors: Raihani, N. J. - Grutter, A. S. - Bshary, R.
Journal: Science

In cases where uninvolved bystanders pay to punish defectors, this behavior has typically been interpreted in terms of group-level rather than individual-level benefits. Male cleaner fish, Labroides dimidiatus, punish their female partner if she cheats while inspecting model clients. Punishment promotes female cooperation and thereby yields direct foraging benefits to the male. Thus, third-party punishment can evolve via self-serving tendencies in a nonhuman species, and this finding may shed light on the evolutionary dynamics of more complex behavior in other animal species, including humans.

MeSH Categories: Animals, *Behavior, Animal, *Cooperative Behavior, Decapoda (Crustacea), Evolution, Feeding Behavior, Female, Fishes, Male, *Perciformes, *Punishment

post to: CiteULike

CRISPR/Cas, the immune system of bacteria and archaea.

Publication Date: 2010 Jan 8 PMID: 20056882
Authors: Horvath, P. - Barrangou, R.
Journal: Science

Microbes rely on diverse defense mechanisms that allow them to withstand viral predation and exposure to invading nucleic acid. In many Bacteria and most Archaea, clustered regularly interspaced short palindromic repeats (CRISPR) form peculiar genetic loci, which provide acquired immunity against viruses and plasmids by targeting nucleic acid in a sequence-specific manner. These hypervariable loci take up genetic material from invasive elements and build up inheritable DNA-encoded immunity over time. Conversely, viruses have devised mutational escape strategies that allow them to circumvent the CRISPR/Cas system, albeit at a cost. CRISPR features may be exploited for typing purposes, epidemiological studies, host-virus ecological surveys, building specific immunity against undesirable genetic elements, and enhancing viral resistance in domesticated microbes.

MeSH Categories: Archaea/*genetics/immunology/virology, Archaeal Proteins/metabolism, Bacteria/*genetics/immunology/virology, Bacterial Proteins/metabolism, Bacteriophages/genetics/physiology, Base Sequence, Conserved Sequence, Gene Transfer, Horizontal, Genes, Archaeal, Genes, Bacterial, *Genetic Loci, *Genome, Archaeal, *Genome, Bacterial, Genome, Viral, Mutation, Plasmids, RNA Interference, RNA, Archaeal/genetics/metabolism, RNA, Bacterial/genetics/metabolism, *Repetitive Sequences, Nucleic Acid

post to: CiteULike

Physics. Electron nematic phases proliferate.

Publication Date: 2010 Jan 8 PMID: 20056881
Authors: Fradkin, E. - Kivelson, S. A.
Journal: Science

post to: CiteULike

Ecology. Valuing common species.

Publication Date: 2010 Jan 8 PMID: 20056880
Authors: Gaston, K. J.
Journal: Science

MeSH Categories: Animals, *Biodiversity, Biomass, Conservation of Natural Resources, *Ecosystem, Plants, Population Dynamics

post to: CiteULike

Ecology. Clarity on honey bee collapse?

Publication Date: 2010 Jan 8 PMID: 20056879
Authors: Ratnieks, F. L. - Carreck, N. L.
Journal: Science

MeSH Categories: Animals, *Beekeeping, *Bees/microbiology/parasitology/physiology/virology, *Colony Collapse/chemically induced/microbiology/parasitology/virology, Crops, Agricultural, Host-Parasite Interactions, Insect Viruses/isolation & purification/physiology, Insecticides/toxicity, Mites/physiology/virology, Nosema/isolation & purification/pathogenicity, Pollination, Prunus

post to: CiteULike

Geochemistry. Deep mantle properties.

Publication Date: 2010 Jan 8 PMID: 20056878
Authors: Hirose, K.
Journal: Science

post to: CiteULike

Molecular biology. Directing the centromere guardian.

Publication Date: 2010 Jan 8 PMID: 20056877
Authors: Javerzat, J. P.
Journal: Science

MeSH Categories: Animals, Cell Cycle Proteins/metabolism, Centromere/*metabolism, Chromosomal Proteins, Non-Histone/*metabolism, *Chromosome Segregation, Chromosomes, Fungal/metabolism, Histones/*metabolism, Interphase, Meiosis, Mitosis, Phosphorylation, Protein-Serine-Threonine Kinases/*metabolism, Schizosaccharomyces/cytology/*metabolism, Schizosaccharomyces pombe Proteins/*metabolism

post to: CiteULike

Science and regulation. Mountaintop mining consequences.

Publication Date: 2010 Jan 8 PMID: 20056876
Authors: Palmer, M. A. - Bernhardt, E. S. - Schlesinger, W. H. - Eshleman, K. N. - Foufoula-Georgiou, E. - Hendryx, M. S. - Lemly, A. D. - Likens, G. E. - Loucks, O. L. - Power, M. E. - White, P. S. - Wilcock, P. R.
Journal: Science

MeSH Categories: Animals, Biodiversity, *Coal Mining/legislation & jurisprudence, *Ecosystem, Environment, Environmental Exposure/*adverse effects, Environmental Remediation/legislation & jurisprudence, Female, Fresh Water/*chemistry, *Government Regulation, Humans, Male, Public Policy, United States, Water Pollutants, Chemical/*analysis

post to: CiteULike

Incentives: encouraging adventurous ideas.

Publication Date: 2010 Jan 8 PMID: 20056875
Authors: Trapani, J. A. - Burgess, A. W. - Hill, D. J.
Journal: Science

MeSH Categories: Australia, *Biomedical Research, Humans, *Motivation, *Neoplasms, *Research Support as Topic

post to: CiteULike

Incentives: stimulus missed an opportunity.

Publication Date: 2010 Jan 8 PMID: 20056874
Authors: Roy, R.
Journal: Science

MeSH Categories: *American Recovery and Reinvestment Act/economics, Financing, Government, *Motivation, *Research, *Science, United States

post to: CiteULike

Financial conflicts of interest worth knowing.

Publication Date: 2010 Jan 8 PMID: 20056873
Authors: Wray, K. B.
Journal: Science

MeSH Categories: *Conflict of Interest, *Disclosure, Publishing/*standards, *Research Support as Topic

post to: CiteULike

Honing the geoengineering strategy.

Publication Date: 2010 Jan 8 PMID: 20056872
Authors: Russell, B. D. - Connell, S. D.
Journal: Science

post to: CiteULike

Accelerator physics. The next big beam?

Publication Date: 2010 Jan 8 PMID: 20056871
Authors: Clery, D.
Journal: Science

MeSH Categories: Medical Oncology/*instrumentation, Nuclear Reactors, Particle Accelerators/*instrumentation, Physics, Protons/therapeutic use, Thorium

post to: CiteULike

Archaeology. Virtual archaeologists recreate parts of ancient worlds.

Publication Date: 2010 Jan 8 PMID: 20056870
Authors: Bawaya, M.
Journal: Science

post to: CiteULike

Materials science. Next wave of metamaterials hopes to fuel the revolution.

Publication Date: 2010 Jan 8 PMID: 20056869
Authors: Service, R. F.
Journal: Science

post to: CiteULike

Research institutions. Plan to merge Texas schools runs into faculty opposition.

Publication Date: 2010 Jan 8 PMID: 20056868
Authors: Kaiser, J.
Journal: Science

MeSH Categories: Biomedical Research, *Faculty, Schools, Medical/economics/*organization & administration, Texas, Universities/economics/*organization & administration

post to: CiteULike

Invasion biology. Gaps in moth logic.

Publication Date: 2010 Jan 8 PMID: 20056867
Authors: Chen, I.
Journal: Science

MeSH Categories: Animals, Australia, California, *Crops, Agricultural, *Insect Control, *Moths, United States, United States Department of Agriculture

post to: CiteULike

Invasion biology. From Medfly to moth: raising a buzz of dissent.

Publication Date: 2010 Jan 8 PMID: 20056866
Authors: Chen, I.
Journal: Science

MeSH Categories: Agriculture, Animals, Australia, California, *Ceratitis capitata, *Crops, Agricultural, *Insect Control, Insecticides, *Moths, Pest Control, Biological, Public Policy

post to: CiteULike

India. Fatal fire and tritium poisoning leave nuclear labs searching for answers.

Publication Date: 2010 Jan 8 PMID: 20056865
Authors: Bagla, P.
Journal: Science

MeSH Categories: *Accidents, Explosions, *Fires, Humans, India, *Laboratories, *Nuclear Reactors, Nuclear Weapons, Security Measures, Terrorism, Tritium/*poisoning, Water Supply

post to: CiteULike

China. After long march, scientists create 'Chinese NIH'.

Publication Date: 2010 Jan 8 PMID: 20056862
Authors: Jiao, L.
Journal: Science

MeSH Categories: Biomedical Research/economics/*organization & administration, China, Financing, Government, Government Agencies/economics/*organization & administration, International Cooperation, National Institutes of Health (U.S.)/organization & administration, Research Support as Topic, United States

post to: CiteULike

Ecology. Europe's bats resist fungal scourge of North America.

Publication Date: 2010 Jan 8 PMID: 20056861
Authors: Stokstad, E.
Journal: Science

MeSH Categories: Animals, Chiroptera/*microbiology, Disease Outbreaks/veterinary, Europe/epidemiology, Mycoses/epidemiology/immunology/microbiology/*veterinary, Onygenales/*isolation & purification/pathogenicity, United States/epidemiology

post to: CiteULike

Japan. 2010 science budget not apocalyptic, as feared.

Publication Date: 2010 Jan 8 PMID: 20056860
Authors: Normile, D.
Journal: Science

post to: CiteULike

Public health. U.S. panel favors wider use of preventive drug treatment.

Publication Date: 2010 Jan 8 PMID: 20056859
Authors: Couzin-Frankel, J.
Journal: Science

MeSH Categories: Advisory Committees, C-Reactive Protein/analysis, Cardiovascular Diseases/*prevention & control, Female, Fluorobenzenes/adverse effects/*therapeutic use, Humans, Hydroxymethylglutaryl-CoA Reductase Inhibitors/adverse, effects/*therapeutic use, Male, Pyrimidines/adverse effects/*therapeutic use, Randomized Controlled Trials as Topic, Sulfonamides/adverse effects/*therapeutic use, United States, United States Food and Drug Administration

post to: CiteULike

Spreading the spirit of EMBO.

Publication Date: 2010 Jan 8 PMID: 20056858
Authors: Leptin, M.
Journal: Science

MeSH Categories: Europe, European Union, International Cooperation, *Molecular Biology, *Organizations/organization & administration/trends, Politics, Public Policy, Research Support as Topic

post to: CiteULike

Axon extension occurs independently of centrosomal microtubule nucleation.

Publication Date: 2010 Feb 5 PMID: 20056854
Authors: Stiess, M. - Maghelli, N. - Kapitein, L. C. - Gomis-Ruth, S. - Wilsch-Brauninger, M. - Hoogenraad, C. C. - Tolic-Norrelykke, I. M. - Bradke, F.
Journal: Science

Microtubules are polymeric protein structures and components of the cytoskeleton. Their dynamic polymerization is important for diverse cellular functions. The centrosome is the classical site of microtubule nucleation and is thought to be essential for axon growth and neuronal differentiation-processes that require microtubule assembly. We found that the centrosome loses its function as a microtubule organizing center during development of rodent hippocampal neurons. Axons still extended and regenerated through acentrosomal microtubule nucleation, and axons continued to grow after laser ablation of the centrosome in early neuronal development. Thus, decentralized microtubule assembly enables axon extension and regeneration, and, after axon initiation, acentrosomal microtubule nucleation arranges the cytoskeleton, which is the source of the sophisticated morphology of neurons.

post to: CiteULike

238U/235U variations in meteorites: extant 247Cm and implications for Pb-Pb dating.

Publication Date: 2010 Jan 22 PMID: 20044543
Authors: Brennecka, G. A. - Weyer, S. - Wadhwa, M. - Janney, P. E. - Zipfel, J. - Anbar, A. D.
Journal: Science

The 238U/235U isotope ratio has long been considered invariant in meteoritic materials (equal to 137.88). This assumption is a cornerstone of the high-precision lead-lead dates that define the absolute age of the solar system. Calcium-aluminum-rich inclusions (CAIs) of the Allende meteorite display variable 238U/235U ratios, ranging between 137.409 +/- 0.039 and 137.885 +/- 0.009. This range implies substantial uncertainties in the ages that were previously determined by lead-lead dating of CAIs, which may be overestimated by several million years. The correlation of uranium isotope ratios with proxies for curium/uranium (that is, thorium/uranium and neodymium/uranium) provides strong evidence that the observed variations of 238U/235U in CAIs were produced by the decay of extant curium-247 to uranium-235 in the early solar system, with an initial 247Cm/235U ratio of approximately 1.1 x 10(-4) to 2.4 x 10(-4).

post to: CiteULike

Detection of Gamma-Ray Emission from the Vela Pulsar Wind Nebula with AGILE.

Publication Date: 2010 Feb 5 PMID: 20044540
Authors: Pellizzoni, A. - Trois, A. - Tavani, M. - Pilia, M. - Giuliani, A. - Pucella, G. - Esposito, P. - Sabatini, S. - Piano, G. - Argan, A. - Barbiellini, G. - Bulgarelli, A. - Burgay, M. - Caraveo, P. - Cattaneo, P. W. - Chen, A. W. - Cocco, V. - Contessi, T. - Costa, E. - D'Ammando, F. - Del Monte, E. - De Paris, G. - Di Cocco, G. - Di Persio, G. - Donnarumma, I. - Evangelista, Y. - Feroci, M. - Ferrari, A. - Fiorini, M. - Fuschino, F. - Galli, M. - Gianotti, F. - Hotan, A. - Labanti, C. - Lapshov, I. - Lazzarotto, F. - Lipari, P. - Longo, F. - Marisaldi, M. - Mastropietro, M. - Mereghetti, S. - Moretti, E. - Morselli, A. - Pacciani, L. - Palfreyman, J. - Perotti, F. - Picozza, P. - Pittori, C. - Possenti, A. - Prest, M. - Rapisarda, M. - Rappoldi, A. - Rossi, E. - Rubini, A. - Santolamazza, P. - Scalise, E. - Soffitta, P. - Striani, E. - Trifoglio, M. - Vallazza, E. - Vercellone, S. - Verrecchia, F. - Vittorini, V. - Zambra, A. - Zanello, D. - Giommi, P. - Colafrancesco, S. - Antonelli, A. - Salotti, L. - D'Amico, N. - Bignami, G. F.
Journal: Science

Pulsars are known to power winds of relativistic particles that can produce bright nebulae by interacting with the surrounding medium. These pulsar wind nebulae are observed by their radio, optical, and x-ray emissions, and in some cases also at TeV (teraelectron volt) energies, but the lack of information in the gamma-ray band precludes drawing a comprehensive multiwavelength picture of their phenomenology and emission mechanisms. Using data from the AGILE satellite, we detected the Vela pulsar wind nebula in the energy range from 100 MeV to 3 GeV. This result constrains the particle population responsible for the GeV emission and establishes a class of gamma-ray emitters that could account for a fraction of the unidentified galactic gamma-ray sources.

post to: CiteULike

Objective confirmation of subjective measures of human well-being: evidence from the U.S.A.

Publication Date: 2010 Jan 29 PMID: 20019249
Authors: Oswald, A. J. - Wu, S.
Journal: Science

A huge research literature, across the behavioral and social sciences, uses information on individuals' subjective well-being. These are responses to questions--asked by survey interviewers or medical personnel--such as, "How happy do you feel on a scale from 1 to 4?" Yet there is little scientific evidence that such data are meaningful. This study examines a 2005-2008 Behavioral Risk Factor Surveillance System random sample of 1.3 million U.S. citizens. Life satisfaction in each U.S. state is measured. Across America, people's answers trace out the same pattern of quality of life as previously estimated, from solely nonsubjective data, in one branch of economics (so-called "compensating differentials" neoclassical theory, originally from Adam Smith). There is a state-by-state match (r = 0.6, P < 0.001) between subjective and objective well-being. This result has some potential to help to unify disciplines.

post to: CiteULike

Spontaneous and x-ray-triggered crystallization at long range in self-assembling filament networks.

Publication Date: 2010 Jan 29 PMID: 20019248
Authors: Cui, H. - Pashuck, E. T. - Velichko, Y. S. - Weigand, S. J. - Cheetham, A. G. - Newcomb, C. J. - Stupp, S. I.
Journal: Science

We report here crystallization at long range in networks of like-charge supramolecular peptide filaments mediated by repulsive forces. The crystallization is spontaneous beyond a given concentration of the molecules that form the filaments but can be triggered by x-rays at lower concentrations. The crystalline domains formed by x-ray irradiation, with interfilament separations of up to 320 angstroms, can be stable for hours after the beam is turned off, and ions that screen charges on the filaments suppress ordering. We hypothesize that the stability of crystalline domains emerges from a balance of repulsive tensions linked to native or x-ray-induced charges and the mechanical compressive entrapment of filaments within a network. Similar phenomena may occur naturally in the cytoskeleton of cells and, if induced externally in biological or artificial systems, lead to possible biomedical and lithographic functions.

post to: CiteULike

p53 controls radiation-induced gastrointestinal syndrome in mice independent of apoptosis.

Publication Date: 2010 Jan 29 PMID: 20019247
Authors: Kirsch, D. G. - Santiago, P. M. - di Tomaso, E. - Sullivan, J. M. - Hou, W. S. - Dayton, T. - Jeffords, L. B. - Sodha, P. - Mercer, K. L. - Cohen, R. - Takeuchi, O. - Korsmeyer, S. J. - Bronson, R. T. - Kim, C. F. - Haigis, K. M. - Jain, R. K. - Jacks, T.
Journal: Science

Acute exposure to ionizing radiation can cause lethal damage to the gastrointestinal (GI) tract, a condition called the GI syndrome. Whether the target cells affected by radiation to cause the GI syndrome are derived from the epithelium or endothelium and whether the target cells die by apoptosis or other mechanisms are controversial issues. Studying mouse models, we found that selective deletion of the proapoptotic genes Bak1 and Bax from the GI epithelium or from endothelial cells did not protect mice from developing the GI syndrome after sub-total-body gamma irradiation. In contrast, selective deletion of p53 from the GI epithelium, but not from endothelial cells, sensitized irradiated mice to the GI syndrome. Transgenic mice overexpressing p53 in all tissues were protected from the GI syndrome after irradiation. These results suggest that the GI syndrome is caused by the death of GI epithelial cells and that these epithelial cells die by a mechanism that is regulated by p53 but independent of apoptosis.

post to: CiteULike

Editorial expression of concern.

Publication Date: 2010 Jan 8 PMID: 20019246
Authors: Alberts, B.
Journal: Science

MeSH Categories: *Genome, *Metabolome, Metabolomics/*methods, Microarray Analysis/*methods

post to: CiteULike

Global analysis of short RNAs reveals widespread promoter-proximal stalling and arrest of Pol II in Drosophila.

Publication Date: 2010 Jan 15 PMID: 20007866
Authors: Nechaev, S. - Fargo, D. C. - dos Santos, G. - Liu, L. - Gao, Y. - Adelman, K.
Journal: Science

Emerging evidence indicates that gene expression in higher organisms is regulated by RNA polymerase II stalling during early transcription elongation. To probe the mechanisms responsible for this regulation, we developed methods to isolate and characterize short RNAs derived from stalled RNA polymerase II in Drosophila cells. Significant levels of these short RNAs were generated from more than one-third of all genes, indicating that promoter-proximal stalling is a general feature of early polymerase elongation. Nucleotide composition of the initially transcribed sequence played an important role in promoting transcriptional stalling by rendering polymerase elongation complexes highly susceptible to backtracking and arrest. These results indicate that the intrinsic efficiency of early elongation can greatly affect gene expression.

MeSH Categories: Animals, Base Composition, Cell Line, Drosophila melanogaster, *Gene Expression Regulation, *Genes, Insect, Genome, Insect, Oligonucleotide Array Sequence Analysis, *Promoter Regions, Genetic, RNA/genetics/*metabolism, RNA Caps/genetics/metabolism, RNA Polymerase II/*metabolism, RNA, Messenger/genetics/metabolism, Transcription Initiation Site, *Transcription, Genetic

post to: CiteULike

Adaptive evolution of pelvic reduction in sticklebacks by recurrent deletion of a Pitx1 enhancer.

Publication Date: 2010 Jan 15 PMID: 20007865
Authors: Chan, Y. F. - Marks, M. E. - Jones, F. C. - Villarreal, G. Jr - Shapiro, M. D. - Brady, S. D. - Southwick, A. M. - Absher, D. M. - Grimwood, J. - Schmutz, J. - Myers, R. M. - Petrov, D. - Jonsson, B. - Schluter, D. - Bell, M. A. - Kingsley, D. M.
Journal: Science

The molecular mechanisms underlying major phenotypic changes that have evolved repeatedly in nature are generally unknown. Pelvic loss in different natural populations of threespine stickleback fish has occurred through regulatory mutations deleting a tissue-specific enhancer of the Pituitary homeobox transcription factor 1 (Pitx1) gene. The high prevalence of deletion mutations at Pitx1 may be influenced by inherent structural features of the locus. Although Pitx1 null mutations are lethal in laboratory animals, Pitx1 regulatory mutations show molecular signatures of positive selection in pelvic-reduced populations. These studies illustrate how major expression and morphological changes can arise from single mutational leaps in natural populations, producing new adaptive alleles via recurrent regulatory alterations in a key developmental control gene.

MeSH Categories: Alleles, Animals, Chromosome Fragile Sites, Chromosome Mapping, Crosses, Genetic, DNA, Intergenic, *Enhancer Elements, Genetic, *Evolution, Fish Proteins/*genetics, Molecular Sequence Data, Mutation, Paired Box Transcription Factors/*genetics, Pelvis/anatomy & histology, Selection, Genetic, *Sequence Deletion, Smegmamorpha/*anatomy & histology/*genetics/growth & development

post to: CiteULike

Tuberculous granuloma induction via interaction of a bacterial secreted protein with host epithelium.

Publication Date: 2010 Jan 22 PMID: 20007864
Authors: Volkman, H. E. - Pozos, T. C. - Zheng, J. - Davis, J. M. - Rawls, J. F. - Ramakrishnan, L.
Journal: Science

Granulomas, organized aggregates of immune cells, are a hallmark of tuberculosis and have traditionally been thought to restrict mycobacterial growth. However, analysis of Mycobacterium marinum in zebrafish has shown that the early granuloma facilitates mycobacterial growth; uninfected macrophages are recruited to the granuloma where they are productively infected by M. marinum. Here, we identified the molecular mechanism by which mycobacteria induce granulomas: The bacterial secreted protein 6-kD early secreted antigenic target (ESAT-6), which has long been implicated in virulence, induced matrix metalloproteinase-9 (MMP9) in epithelial cells neighboring infected macrophages. MMP9 enhanced recruitment of macrophages, which contributed to nascent granuloma maturation and bacterial growth. Disruption of MMP9 function attenuated granuloma formation and bacterial growth. Thus, interception of epithelial MMP9 production could hold promise as a host-targeting tuberculosis therapy.

MeSH Categories: Animals, Antigens, Bacterial/genetics/*metabolism, Bacterial Proteins/genetics/*metabolism, Disease Models, Animal, Embryo, Nonmammalian/microbiology, Enzyme Induction, Epithelial Cells/*enzymology, Granuloma/metabolism/*microbiology, Macrophages/microbiology/physiology, Matrix Metalloproteinase 9/genetics/*metabolism, Mycobacterium Infections, Atypical/*microbiology, Mycobacterium marinum/growth & development/metabolism/*pathogenicity, Mycobacterium tuberculosis/genetics/pathogenicity, Oligoribonucleotides, Antisense, Recombinant Proteins/metabolism, Tuberculosis/*microbiology, Virulence Factors/genetics/*metabolism, Zebrafish/embryology, Zebrafish Proteins/genetics/metabolism

post to: CiteULike

Iapetus: unique surface properties and a global color dichotomy from Cassini imaging.

Publication Date: 2010 Jan 22 PMID: 20007863
Authors: Denk, T. - Neukum, G. - Roatsch, T. - Porco, C. C. - Burns, J. A. - Galuba, G. G. - Schmedemann, N. - Helfenstein, P. - Thomas, P. C. - Wagner, R. J. - West, R. A.
Journal: Science

Since 2004, Saturn's moon Iapetus has been observed repeatedly with the Imaging Science Subsystem of the Cassini spacecraft. The images show numerous impact craters down to the resolution limit of approximately 10 meters per pixel. Small, bright craters within the dark hemisphere indicate a dark blanket thickness on the order of meters or less. Dark, equator-facing and bright, poleward-facing crater walls suggest temperature-driven water-ice sublimation as the process responsible for local albedo patterns. Imaging data also reveal a global color dichotomy, wherein both dark and bright materials on the leading side have a substantially redder color than the respective trailing-side materials. This global pattern indicates an exogenic origin for the redder leading-side parts and suggests that the global color dichotomy initiated the thermal formation of the global albedo dichotomy.

MeSH Categories: Color, Extraterrestrial Environment, *Ice, *Saturn, Spacecraft, Temperature, *Water

post to: CiteULike

Formation of Iapetus' extreme albedo dichotomy by exogenically triggered thermal ice migration.

Publication Date: 2010 Jan 22 PMID: 20007862
Authors: Spencer, J. R. - Denk, T.
Journal: Science

The extreme albedo asymmetry of Saturn's moon Iapetus, which is about 10 times as bright on its trailing hemisphere as on its leading hemisphere, has been an enigma for three centuries. Deposition of exogenic dark material on the leading side has been proposed as a cause, but this alone cannot explain the global shape, sharpness, and complexity of the transition between Iapetus' bright and dark terrain. We demonstrate that all these characteristics, and the asymmetry's large amplitude, can be plausibly explained by runaway global thermal migration of water ice, triggered by the deposition of dark material on the leading hemisphere. This mechanism is unique to Iapetus among the saturnian satellites because its slow rotation produces unusually high daytime temperatures and water ice sublimation rates for a given albedo.

MeSH Categories: Extraterrestrial Environment, *Ice, *Saturn, Spacecraft, Temperature, *Water

post to: CiteULike

Iron partitioning and density changes of pyrolite in Earth's lower mantle.

Publication Date: 2010 Jan 8 PMID: 19965719
Authors: Irifune, T. - Shinmei, T. - McCammon, C. A. - Miyajima, N. - Rubie, D. C. - Frost, D. J.
Journal: Science

Phase transitions and the chemical composition of minerals in Earth's interior influence geophysical interpretations of its deep structure and dynamics. A pressure-induced spin transition in olivine has been suggested to influence iron partitioning and depletion, resulting in a distinct layered structure in Earth's lower mantle. For a more realistic mantle composition (pyrolite), we observed a considerable change in the iron-magnesium partition coefficient at about 40 gigapascals that is explained by a spin transition at much lower pressures. However, only a small depletion of iron is observed in the major high-pressure phase (magnesium silicate perovskite), which may be explained by preferential retention of the iron ion Fe3+. Changes in mineral proportions or density are not associated with the change in partition coefficient. The observed density profile agrees well with seismological models, which suggests that pyrolite is a good model composition for the upper to middle parts of the lower mantle.

post to: CiteULike

Therapeutic silencing of microRNA-122 in primates with chronic hepatitis C virus infection.

Publication Date: 2010 Jan 8 PMID: 19965718
Authors: Lanford, R. E. - Hildebrandt-Eriksen, E. S. - Petri, A. - Persson, R. - Lindow, M. - Munk, M. E. - Kauppinen, S. - Orum, H.
Journal: Science

The liver-expressed microRNA-122 (miR-122) is essential for hepatitis C virus (HCV) RNA accumulation in cultured liver cells, but its potential as a target for antiviral intervention has not been assessed. We found that treatment of chronically infected chimpanzees with a locked nucleic acid (LNA)-modified oligonucleotide (SPC3649) complementary to miR-122 leads to long-lasting suppression of HCV viremia, with no evidence of viral resistance or side effects in the treated animals. Furthermore, transcriptome and histological analyses of liver biopsies demonstrated derepression of target mRNAs with miR-122 seed sites, down-regulation of interferon-regulated genes, and improvement of HCV-induced liver pathology. The prolonged virological response to SPC3649 treatment without HCV rebound holds promise of a new antiviral therapy with a high barrier to resistance.

MeSH Categories: Animals, Antiviral Agents/adverse effects/blood/*therapeutic use, Chemokine CXCL10/blood, Cholesterol/blood, Disease Models, Animal, Drug Evaluation, Preclinical, Drug Resistance, Viral, Female, Gene Expression Profiling, Gene Expression Regulation, Hepacivirus/drug effects/genetics/isolation & purification/physiology, Hepatitis C, Chronic/*drug therapy/genetics/virology, Interferons/metabolism, Liver/metabolism/virology, Male, MicroRNAs/*antagonists & inhibitors/genetics/metabolism, *Pan troglodytes, Phosphorothioate Oligonucleotides/adverse effects/blood/*therapeutic use, RNA, Messenger/genetics/metabolism, RNA, Viral/metabolism, Viral Load, Viremia/drug therapy

post to: CiteULike

Overexpression of alpha2A-adrenergic receptors contributes to type 2 diabetes.

Publication Date: 2010 Jan 8 PMID: 19965390
Authors: Rosengren, A. H. - Jokubka, R. - Tojjar, D. - Granhall, C. - Hansson, O. - Li, D. Q. - Nagaraj, V. - Reinbothe, T. M. - Tuncel, J. - Eliasson, L. - Groop, L. - Rorsman, P. - Salehi, A. - Lyssenko, V. - Luthman, H. - Renstrom, E.
Journal: Science

Several common genetic variations have been associated with type 2 diabetes, but the exact disease mechanisms are still poorly elucidated. Using congenic strains from the diabetic Goto-Kakizaki rat, we identified a 1.4-megabase genomic locus that was linked to impaired insulin granule docking at the plasma membrane and reduced beta cell exocytosis. In this locus, Adra2a, encoding the alpha2A-adrenergic receptor [alpha(2A)AR], was significantly overexpressed. Alpha(2A)AR mediates adrenergic suppression of insulin secretion. Pharmacological receptor antagonism, silencing of receptor expression, or blockade of downstream effectors rescued insulin secretion in congenic islets. Furthermore, we identified a single-nucleotide polymorphism in the human ADRA2A gene for which risk allele carriers exhibited overexpression of alpha(2A)AR, reduced insulin secretion, and increased type 2 diabetes risk. Human pancreatic islets from risk allele carriers exhibited reduced granule docking and secreted less insulin in response to glucose; both effects were counteracted by pharmacological alpha(2A)AR antagonists.

MeSH Categories: Adolescent, Adrenergic alpha-Agonists/pharmacology, Adrenergic alpha-Antagonists/pharmacology, Adult, Aged, Animals, Animals, Congenic, Blood Glucose/metabolism, Cell Membrane/metabolism, Cyclic AMP/metabolism, Diabetes Mellitus, Type 2/*genetics/metabolism, Exocytosis, Genetic Association Studies, Genetic Predisposition to Disease, Humans, Insulin/blood/*secretion, Insulin-Secreting Cells/*secretion, Middle Aged, Polymorphism, Single Nucleotide, RNA Interference, Rats, Rats, Inbred Strains, Receptors, Adrenergic, alpha-2/agonists/antagonists &, inhibitors/*genetics/*metabolism, Risk Factors, Secretory Vesicles/metabolism, Up-Regulation, Young Adult

post to: CiteULike

Direct imaging of bridged twin protoplanetary disks in a young multiple star.

Publication Date: 2010 Jan 15 PMID: 19965388
Authors: Mayama, S. - Tamura, M. - Hanawa, T. - Matsumoto, T. - Ishii, M. - Pyo, T. S. - Suto, H. - Naoi, T. - Kudo, T. - Hashimoto, J. - Nishiyama, S. - Kuzuhara, M. - Hayashi, M.
Journal: Science

Studies of the structure and evolution of protoplanetary disks are important for understanding star and planet formation. Here we present the direct image of an interacting binary protoplanetary system. Both circumprimary and circumsecondary disks are resolved in the near-infrared. There is a bridge of infrared emission connecting the two disks and a long spiral arm extending from the circumprimary disk. Numerical simulations show that the bridge corresponds to gas flow and a shock wave caused by the collision of gas rotating around the primary and secondary stars. Fresh material streams along the spiral arm, consistent with the theoretical scenarios in which gas is replenished from a circummultiple reservoir.

post to: CiteULike

Phosphorylation of H2A by Bub1 prevents chromosomal instability through localizing shugoshin.

Publication Date: 2010 Jan 8 PMID: 19965387
Authors: Kawashima, S. A. - Yamagishi, Y. - Honda, T. - Ishiguro, K. - Watanabe, Y.
Journal: Science

Bub1 is a multi-task protein kinase required for proper chromosome segregation in eukaryotes. Impairment of Bub1 in humans may lead to chromosomal instability (CIN) or tumorigenesis. Yet, the primary cellular substrate of Bub1 has remained elusive. Here, we show that Bub1 phosphorylates the conserved serine 121 of histone H2A in fission yeast Schizosaccharomyces pombe. The h2a-SA mutant, in which all cellular H2A-S121 is replaced by alanine, phenocopies the bub1 kinase-dead mutant (bub1-KD) in losing the centromeric localization of shugoshin proteins. Artificial tethering of shugoshin to centromeres largely restores the h2a-SA or bub1-KD-related CIN defects, a function that is evolutionally conserved. Thus, Bub1 kinase creates a mark for shugoshin localization and the correct partitioning of chromosomes.

MeSH Categories: Animals, Centromere/*metabolism, *Chromosomal Instability, Chromosomal Proteins, Non-Histone/genetics/*metabolism, *Chromosome Segregation, Chromosomes, Fungal/metabolism, Histones/*metabolism, Humans, Kinetochores/metabolism, Meiosis, Mice, Mitosis, Nucleosomes/metabolism, Phosphorylation, Protein-Serine-Threonine Kinases/genetics/*metabolism, Recombinant Proteins/metabolism, Saccharomyces cerevisiae/genetics/metabolism, Saccharomyces cerevisiae Proteins/genetics/metabolism, Schizosaccharomyces/cytology/genetics/*metabolism, Schizosaccharomyces pombe Proteins/genetics/*metabolism, Serine/metabolism

post to: CiteULike

Structure of an RNA polymerase II-TFIIB complex and the transcription initiation mechanism.

Publication Date: 2010 Jan 8 PMID: 19965383
Authors: Liu, X. - Bushnell, D. A. - Wang, D. - Calero, G. - Kornberg, R. D.
Journal: Science

Previous x-ray crystal structures have given insight into the mechanism of transcription and the role of general transcription factors in the initiation of the process. A structure of an RNA polymerase II-general transcription factor TFIIB complex at 4.5 angstrom resolution revealed the amino-terminal region of TFIIB, including a loop termed the "B finger," reaching into the active center of the polymerase where it may interact with both DNA and RNA, but this structure showed little of the carboxyl-terminal region. A new crystal structure of the same complex at 3.8 angstrom resolution obtained under different solution conditions is complementary with the previous one, revealing the carboxyl-terminal region of TFIIB, located above the polymerase active center cleft, but showing none of the B finger. In the new structure, the linker between the amino- and carboxyl-terminal regions can also be seen, snaking down from above the cleft toward the active center. The two structures, taken together with others previously obtained, dispel long-standing mysteries of the transcription initiation process.

MeSH Categories: Amino Acid Sequence, Catalytic Domain, Crystallography, X-Ray, Models, Molecular, Molecular Sequence Data, Protein Conformation, Protein Interaction Domains and Motifs, Protein Structure, Secondary, Protein Structure, Tertiary, RNA Polymerase II/*chemistry/*metabolism, Repetitive Sequences, Amino Acid, Saccharomyces cerevisiae/chemistry/genetics/metabolism, Saccharomyces cerevisiae Proteins/*chemistry/*metabolism, Transcription Factor TFIIB/*chemistry/*metabolism, *Transcription, Genetic

post to: CiteULike

Two white dwarfs with oxygen-rich atmospheres.

Publication Date: 2010 Jan 8 PMID: 19965382
Authors: Gansicke, B. T. - Koester, D. - Girven, J. - Marsh, T. R. - Steeghs, D.
Journal: Science

Stars with masses ranging from 7 to 10 times the mass of the Sun end their lives either as massive white dwarfs or weak type II supernovae, but there are only limited observational constraints on either evolutionary channel. Here we report the detection of two white dwarfs with large photospheric oxygen abundances, implying that they are bare oxygen-neon cores and that they may have descended from the most massive progenitors that avoid core collapse.

post to: CiteULike

Ligand-enabled reactivity and selectivity in a synthetically versatile aryl C-H olefination.

Publication Date: 2010 Jan 15 PMID: 19965380
Authors: Wang, D. H. - Engle, K. M. - Shi, B. F. - Yu, J. Q.
Journal: Science

The Mizoroki-Heck reaction, which couples aryl halides with olefins, has been widely used to stitch together the carbogenic cores of numerous complex organic molecules. Given that the position-selective introduction of a halide onto an arene is not always straightforward, direct olefination of aryl carbon-hydrogen (C-H) bonds would obviate the inefficiencies associated with generating halide precursors or their equivalents. However, methods for carrying out such a reaction have suffered from narrow substrate scope and low positional selectivity. We report an operationally simple, atom-economical, carboxylate-directed Pd(II)-catalyzed C-H olefination reaction with phenylacetic acid and 3-phenylpropionic acid substrates, using oxygen at atmospheric pressure as the oxidant. The positional selectivity can be tuned by introducing amino acid derivatives as ligands. We demonstrate the versatility of the method through direct elaboration of commercial drug scaffolds and efficient syntheses of 2-tetralone and naphthoic acid natural product cores.

MeSH Categories: Alkenes/*chemistry, Amino Acids/chemistry, Carbon/*chemistry, Carboxylic Acids/*chemical synthesis/chemistry, Catalysis, Hydrogen/*chemistry, Ligands, Molecular Structure, Naphthalenes/*chemical synthesis/chemistry, Oxidants/chemistry, Oxygen/chemistry, Palladium/chemistry, Phenylacetates/chemistry, Phenylpropionates/chemistry, Physicochemical Processes, Tetralones/*chemical synthesis

post to: CiteULike

Tetrathiomolybdate inhibits copper trafficking proteins through metal cluster formation.

Publication Date: 2010 Jan 15 PMID: 19965379
Authors: Alvarez, H. M. - Xue, Y. - Robinson, C. D. - Canalizo-Hernandez, M. A. - Marvin, R. G. - Kelly, R. A. - Mondragon, A. - Penner-Hahn, J. E. - O'Halloran, T. V.
Journal: Science

Tetrathiomolybdate (TM) is an orally active agent for treatment of disorders of copper metabolism. Here we describe how TM inhibits proteins that regulate copper physiology. Crystallographic results reveal that the surprising stability of the drug complex with the metallochaperone Atx1 arises from formation of a sulfur-bridged copper-molybdenum cluster reminiscent of those found in molybdenum and iron sulfur proteins. Spectroscopic studies indicate that this cluster is stable in solution and corresponds to physiological clusters isolated from TM-treated Wilson's disease animal models. Finally, mechanistic studies show that the drug-metallochaperone inhibits metal transfer functions between copper-trafficking proteins. The results are consistent with a model wherein TM can directly and reversibly down-regulate copper delivery to secreted metalloenzymes and suggest that proteins involved in metal regulation might be fruitful drug targets.

MeSH Categories: Carrier Proteins/*antagonists & inhibitors/chemistry/*metabolism, Cation Transport Proteins/metabolism, Copper/chemistry/*metabolism, Crystallography, X-Ray, Ligands, Metallochaperones/*antagonists & inhibitors/chemistry/*metabolism, Models, Chemical, Models, Molecular, Molecular Structure, Molybdenum/chemistry/*metabolism/*pharmacology, Oxidation-Reduction, Physicochemical Processes, Protein Conformation, Saccharomyces cerevisiae Proteins/*antagonists &, inhibitors/chemistry/*metabolism

post to: CiteULike