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- Mars North Polar Deposits: Stratigraphy, Age, and Geodynamical Response.Publication Date: 2008 May 15 PMID: 18483402
Authors: Phillips, R. J. - Zuber, M. T. - Smrekar, S. E. - Mellon, M. T. - Head, J. W. - Tanaka, K. L. - Putzig, N. E. - Milkovich, S. M. - Campbell, B. A. - Plaut, J. J. - Safaeinili, A. - Seu, R. - Biccari, D. - Carter, L. M. - Picardi, G. - Orosei, R. - Mohit, P. S. - Heggy, E. - Zurek, R. W. - Egan, A. F. - Giacomoni, E. - Russo, F. - Cutigni, M. - Pettinelli, E. - Holt, J. W. - Leuschen, C. J. - Marinangeli, L.
Journal: Science
The sounding radar SHARAD on the Mars Reconnaissance Orbiter has imaged the internal stratigraphy of the North Polar Layered Deposits of Mars. Radar reflections within the deposits reveal laterally-continuous deposition of layers, which consist typically of four packets of finely-spaced reflectors separated by homogeneous inter-packet regions of nearly pure ice. The packet/inter-packet structure can be explained by likely ~million-year periodicities in Mars' obliquity or orbital eccentricity. The observed ~100-m maximum deflection of the underlying substrate in response to the ice load implies that the present-day thickness of an equilibrium elastic lithosphere is greater than 300 km. Alternatively, the response to the load may be in a transient state controlled by mantle viscosity. Both scenarios likely require that Mars has a sub-chondritic abundance of heat-producing elements.
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- Activation of the Cellular DNA Damage Response in the Absence of DNA Lesions.Publication Date: 2008 May 15 PMID: 18483401
Authors: Soutoglou, E. - Misteli, T.
Journal: Science
The cellular DNA damage response (DDR) is initiated by the rapid recruitment of repair factors to the site of DNA damage to form a multiprotein repair complex. How the repair complex senses damaged DNA and then activates the DDR is not well understood. Here we demonstrate that prolonged binding of DNA repair factors to chromatin can elicit DDR in an ATM- and DNAPK-dependent fashion in the absence of DNA damage. Targeting of single repair factors to chromatin revealed a hierarchy of protein interactions within the repair complex and suggests amplification of the damage signal. We conclude that activation of DDR does not require DNA damage and stable association of repair factors with chromatin is likely a critical step in triggering, amplifying and maintaining the DDR signal.
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- An Eccentric Pulsar: Result of a Threesome?Publication Date: 2008 May 15 PMID: 18483400
Authors: van den Heuvel, E. P.
Journal: Science
Observation of an eccentric millisecond binary pulsar challenges the standard model of pulsar formation.
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- An Eccentric Binary Millisecond Pulsar in the Galactic Plane.Publication Date: 2008 May 15 PMID: 18483399
Authors: Champion, D. J. - Ransom, S. M. - Lazarus, P. - Camilo, F. - Bassa, C. - Kaspi, V. M. - Nice, D. J. - Freire, P. C. - Stairs, I. H. - van Leeuwen, J. - Stappers, B. W. - Cordes, J. M. - Hessels, J. W. - Lorimer, D. R. - Arzoumanian, Z. - Backer, D. C. - Bhat, N. D. - Chatterjee, S. - Cognard, I. - Deneva, J. S. - Faucher-Giguere, C. A. - Gaensler, B. M. - Han, J. - Jenet, F. A. - Kasian, L. - Kondratiev, V. I. - Kramer, M. - Lazio, J. - McLaughlin, M. A. - Venkataraman, A. - Vlemmings, W.
Journal: Science
Binary pulsar systems are superb probes of stellar and binary evolution and the physics of extreme environments. In a survey with the Arecibo telescope, we have found PSR J1903+0327, a radio pulsar with a rotational period of 2.15 milliseconds in a highly eccentric (e = 0.44) 95-day orbit around a solar mass companion. Infrared observations identify a possible main-sequence companion star. Conventional binary stellar evolution models predict neither large orbital eccentricities nor main-sequence companions around millisecond pulsars. Alternative formation scenarios involve recycling a neutron star in a globular cluster, then ejecting it into the Galactic disk or membership in a hierarchical triple system. A relativistic analysis of timing observations of the pulsar finds its mass to be 1.74 +/- 0.04 Mmiddle dot in circle, an unusually high value.
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- Widespread Translational Inhibition by Plant miRNAs and siRNAs.Publication Date: 2008 May 15 PMID: 18483398
Authors: Brodersen, P. - Sakvarelidze-Achard, L. - Bruun-Rasmussen, M. - Dunoyer, P. - Yamamoto, Y. Y. - Sieburth, L. - Voinnet, O.
Journal: Science
High complementarity between plant miRNAs and their mRNA targets is thought to cause silencing prevalently by endonucleolytic cleavage. We have isolated Arabidopsis mutants defective in miRNA action. Their analysis provides evidence that plant miRNA-guided silencing has a widespread translational inhibitory component that is genetically separable from endonucleolytic cleavage. We further show that the same is true of silencing mediated by short interfering (si)RNA populations. Translational repression is effected in part by the ARGONAUTE proteins AGO1 and AGO10. It also requires the activity of the microtubule-severing enzyme katanin, implicating cytoskeleton dynamics in miRNA action as recently suggested from animal studies. Also as in animals, the decapping component VCS/Ge-1 is required for translational repression by miRNAs, suggesting that the underlying mechanisms in the two kingdoms are related.
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- Regulation of the cellular heat shock response in Caenorhabditis elegans by thermosensory neurons.Publication Date: 2008 May 9 PMID: 18467592
Authors: Prahlad, V. - Cornelius, T. - Morimoto, R. I.
Journal: Science
Temperature pervasively affects all cellular processes. In response to a rapid increase in temperature, all cells undergo a heat shock response, an ancient and highly conserved program of stress-inducible gene expression, to reestablish cellular homeostasis. In isolated cells, the heat shock response is initiated by the presence of misfolded proteins and therefore thought to be cell-autonomous. In contrast, we show that within the metazoan Caenorhabditis elegans, the heat shock response of somatic cells is not cell-autonomous but rather depends on the thermosensory neuron, AFD, which senses ambient temperature and regulates temperature-dependent behavior. We propose a model whereby this loss of cell autonomy serves to integrate behavioral, metabolic, and stress-related responses to establish an organismal response to environmental change.
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- Discovery of a cytokine and its receptor by functional screening of the extracellular proteome.Publication Date: 2008 May 9 PMID: 18467591
Authors: Lin, H. - Lee, E. - Hestir, K. - Leo, C. - Huang, M. - Bosch, E. - Halenbeck, R. - Wu, G. - Zhou, A. - Behrens, D. - Hollenbaugh, D. - Linnemann, T. - Qin, M. - Wong, J. - Chu, K. - Doberstein, S. K. - Williams, L. T.
Journal: Science
To understand the system of secreted proteins and receptors involved in cell-cell signaling, we produced a comprehensive set of recombinant secreted proteins and the extracellular domains of transmembrane proteins, which constitute most of the protein components of the extracellular space. Each protein was tested in a suite of assays that measured metabolic, growth, or transcriptional responses in diverse cell types. The pattern of responses across assays was analyzed for the degree of functional selectivity of each protein. One of the highly selective proteins was a previously undescribed ligand, designated interleukin-34 (IL-34), which stimulates monocyte viability but does not affect responses in a wide spectrum of other assays. In a separate functional screen, we used a collection of extracellular domains of transmembrane proteins to discover the receptor for IL-34, which was a known cytokine receptor, colony-stimulating factor 1 (also called macrophage colony-stimulating factor) receptor. This systematic approach is thus useful for discovering new ligands and receptors and assessing the functional selectivity of extracellular regulatory proteins.
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- Adaptive phenotypic plasticity in response to climate change in a wild bird population.Publication Date: 2008 May 9 PMID: 18467590
Authors: Charmantier, A. - McCleery, R. H. - Cole, L. R. - Perrins, C. - Kruuk, L. E. - Sheldon, B. C.
Journal: Science
Rapid climate change has been implicated as a cause of evolution in poorly adapted populations. However, phenotypic plasticity provides the potential for organisms to respond rapidly and effectively to environmental change. Using a 47-year population study of the great tit (Parus major) in the United Kingdom, we show that individual adjustment of behavior in response to the environment has enabled the population to track a rapidly changing environment very closely. Individuals were markedly invariant in their response to environmental variation, suggesting that the current response may be fixed in this population. Phenotypic plasticity can thus play a central role in tracking environmental change; understanding the limits of plasticity is an important goal for future research.
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- Phosphorylation of retinoblastoma protein by viral protein with cyclin-dependent kinase function.Publication Date: 2008 May 9 PMID: 18467589
Authors: Hume, A. J. - Finkel, J. S. - Kamil, J. P. - Coen, D. M. - Culbertson, M. R. - Kalejta, R. F.
Journal: Science
As obligate intracellular parasites, viruses expertly modify cellular processes to facilitate their replication and spread, often by encoding genes that mimic the functions of cellular proteins while lacking regulatory features that modify their activity. We show that the human cytomegalovirus UL97 protein has activities similar to cellular cyclin-cyclin-dependent kinase (CDK) complexes. UL97 phosphorylated and inactivated the retinoblastoma tumor suppressor, stimulated cell cycle progression in mammalian cells, and rescued proliferation of Saccharomyces cerevisiae lacking CDK activity. UL97 is not inhibited by the CDK inhibitor p21 and lacks amino acid residues conserved in the CDKs that permit the attenuation of kinase activity. Thus, UL97 represents a functional ortholog of cellular CDKs that is immune from normal CDK control mechanisms.
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- Architecture of a charge-transfer state regulating light harvesting in a plant antenna protein.Publication Date: 2008 May 9 PMID: 18467588
Authors: Ahn, T. K. - Avenson, T. J. - Ballottari, M. - Cheng, Y. C. - Niyogi, K. K. - Bassi, R. - Fleming, G. R.
Journal: Science
Energy-dependent quenching of excess absorbed light energy (qE) is a vital mechanism for regulating photosynthetic light harvesting in higher plants. All of the physiological characteristics of qE have been positively correlated with charge transfer between coupled chlorophyll and zeaxanthin molecules in the light-harvesting antenna of photosystem II (PSII). We found evidence for charge-transfer quenching in all three of the individual minor antenna complexes of PSII (CP29, CP26, and CP24), and we conclude that charge-transfer quenching in CP29 involves a delocalized state of an excitonically coupled chlorophyll dimer. We propose that reversible conformational changes in CP29 can "tune" the electronic coupling between the chlorophylls in this dimer, thereby modulating the energy of the chlorophyll-zeaxanthin charge-transfer state and switching on and off the charge-transfer quenching during qE.
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- Spatial regulators for bacterial cell division self-organize into surface waves in vitro.Publication Date: 2008 May 9 PMID: 18467587
Authors: Loose, M. - Fischer-Friedrich, E. - Ries, J. - Kruse, K. - Schwille, P.
Journal: Science
In the bacterium Escherichia coli, the Min proteins oscillate between the cell poles to select the cell center as division site. This dynamic pattern has been proposed to arise by self-organization of these proteins, and several models have suggested a reaction-diffusion type mechanism. Here, we found that the Min proteins spontaneously formed planar surface waves on a flat membrane in vitro. The formation and maintenance of these patterns, which extended for hundreds of micrometers, required adenosine 5'-triphosphate (ATP), and they persisted for hours. We present a reaction-diffusion model of the MinD and MinE dynamics that accounts for our experimental observations and also captures the in vivo oscillations.
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- Monte Verde: seaweed, food, medicine, and the peopling of South America.Publication Date: 2008 May 9 PMID: 18467586
Authors: Dillehay, T. D. - Ramirez, C. - Pino, M. - Collins, M. B. - Rossen, J. - Pino-Navarro, J. D.
Journal: Science
The identification of human artifacts at the early archaeological site of Monte Verde in southern Chile has raised questions of when and how people reached the tip of South America without leaving much other evidence in the New World. Remains of nine species of marine algae were recovered from hearths and other features at Monte Verde II, an upper occupational layer, and were directly dated between 14,220 and 13,980 calendar years before the present ( approximately 12,310 and 12,290 carbon-14 years ago). These findings support the archaeological interpretation of the site and indicate that the site's inhabitants used seaweed from distant beaches and estuarine environments for food and medicine. These data are consistent with the ideas that an early settlement of South America was along the Pacific coast and that seaweeds were important to the diet and health of early humans in the Americas.
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- Conditional dynamics of interacting quantum dots.Publication Date: 2008 May 9 PMID: 18467585
Authors: Robledo, L. - Elzerman, J. - Jundt, G. - Atature, M. - Hogele, A. - Falt, S. - Imamoglu, A.
Journal: Science
Conditional quantum dynamics, where the quantum state of one system controls the outcome of measurements on another quantum system, is at the heart of quantum information processing. We demonstrate conditional dynamics for two coupled quantum dots, whereby the probability that one quantum dot makes a transition to an optically excited state is controlled by the presence or absence of an optical excitation in the neighboring dot. Interaction between the dots is mediated by the tunnel coupling between optically excited states and can be optically gated by applying a laser field of the right frequency. Our results represent substantial progress toward realization of an optically effected controlled-phase gate between two solid-state qubits.
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- Controlled phase shifts with a single quantum dot.Publication Date: 2008 May 9 PMID: 18467584
Authors: Fushman, I. - Englund, D. - Faraon, A. - Stoltz, N. - Petroff, P. - Vuckovic, J.
Journal: Science
Optical nonlinearities enable photon-photon interaction and lie at the heart of several proposals for quantum information processing, quantum nondemolition measurements of photons, and optical signal processing. To date, the largest nonlinearities have been realized with single atoms and atomic ensembles. We show that a single quantum dot coupled to a photonic crystal nanocavity can facilitate controlled phase and amplitude modulation between two modes of light at the single-photon level. At larger control powers, we observed phase shifts up to pi/4 and amplitude modulation up to 50%. This was accomplished by varying the photon number in the control beam at a wavelength that was the same as that of the signal, or at a wavelength that was detuned by several quantum dot linewidths from the signal. Our results present a step toward quantum logic devices and quantum nondemolition measurements on a chip.
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- Climate-driven ecosystem succession in the Sahara: the past 6000 years.Publication Date: 2008 May 9 PMID: 18467583
Authors: Kropelin, S. - Verschuren, D. - Lezine, A. M. - Eggermont, H. - Cocquyt, C. - Francus, P. - Cazet, J. P. - Fagot, M. - Rumes, B. - Russell, J. M. - Darius, F. - Conley, D. J. - Schuster, M. - von Suchodoletz, H. - Engstrom, D. R.
Journal: Science
Desiccation of the Sahara since the middle Holocene has eradicated all but a few natural archives recording its transition from a "green Sahara" to the present hyperarid desert. Our continuous 6000-year paleoenvironmental reconstruction from northern Chad shows progressive drying of the regional terrestrial ecosystem in response to weakening insolation forcing of the African monsoon and abrupt hydrological change in the local aquatic ecosystem controlled by site-specific thresholds. Strong reductions in tropical trees and then Sahelian grassland cover allowed large-scale dust mobilization from 4300 calendar years before the present (cal yr B.P.). Today's desert ecosystem and regional wind regime were established around 2700 cal yr B.P. This gradual rather than abrupt termination of the African Humid Period in the eastern Sahara suggests a relatively weak biogeophysical feedback on climate.
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- Toward an AIDS vaccine.Publication Date: 2008 May 9 PMID: 18467582
Authors: Walker, B. D. - Burton, D. R.
Journal: Science
A quarter century of scientific discovery has been applied to developing an AIDS vaccine, yet this goal remains elusive. Specific characteristics of the virus, including the extreme genetic variability in circulating viral isolates worldwide, biological properties of HIV that impede immune attack, and a high mutation rate that allows for rapid escape from adaptive immune responses, render this a huge challenge. However, evidence of protection against AIDS viruses in animal models and control of HIV in humans under certain circumstances, together with scientific advances in understanding disease pathogenesis, provide a strong rationale and objective paths to continue the pursuit of an effective AIDS vaccine to stem the global epidemic.
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- Biogeochemistry. News about nitrogen.Publication Date: 2008 May 9 PMID: 18467581
Authors: Horner-Devine, M. C. - Martiny, A. C.
Journal: Science
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- Materials science. High-frequency chip connections.Publication Date: 2008 May 9 PMID: 18467580
Authors: Spencer, T. J. - Osborn, T. - Kohl, P. A.
Journal: Science
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- Biochemistry. Tinkering with acellular division.Publication Date: 2008 May 9 PMID: 18467579
Authors: Lutkenhaus, J.
Journal: Science
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- AIDS/HIV. A STEP into darkness or light?Publication Date: 2008 May 9 PMID: 18467578
Authors: Moore, J. P. - Klasse, P. J. - Dolan, M. J. - Ahuja, S. K.
Journal: Science
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- Ecology. How the Sahara became dry.Publication Date: 2008 May 9 PMID: 18467577
Authors: Holmes, J. A.
Journal: Science
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- Physics. Designer atomic nuclei.Publication Date: 2008 May 9 PMID: 18467576
Authors: Sherrill, B. M.
Journal: Science
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- Public health. Reassessing HIV prevention.Publication Date: 2008 May 9 PMID: 18467575
Authors: Potts, M. - Halperin, D. T. - Kirby, D. - Swidler, A. - Marseille, E. - Klausner, J. D. - Hearst, N. - Wamai, R. G. - Kahn, J. G. - Walsh, J.
Journal: Science
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- Comment on "Absence of cooling in New Zealand and the adjacent ocean during the Younger Dryas chronozone".Publication Date: 2008 May 9 PMID: 18467574
Authors: Applegate, P. J. - Lowell, T. V. - Alley, R. B.
Journal: Science
Barrows et al. (Reports, 5 October 2007, p. 86) presented cosmogenic exposure dates and data from an ocean sediment core that challenge evidence for glacier advance in New Zealand during the Younger Dryas event. We use modeling of geomorphic processes to argue that their cosmogenic exposure dates are inconclusive.
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- Living up to ancient civilizations.Publication Date: 2008 May 9 PMID: 18467573
Authors: Glasby, G. P.
Journal: Science
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- Data discrepancies in solar-climate link.Publication Date: 2008 May 9 PMID: 18467572
Authors: Pierrehumbert, R. T.
Journal: Science
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- Evolution and faith: empathy is crucial.Publication Date: 2008 May 9 PMID: 18467571
Authors: Whipple, A.
Journal: Science
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- Evolution and faith: empathy is misplaced.Publication Date: 2008 May 9 PMID: 18467570
Authors: Stevens, C. W.
Journal: Science
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- Lost in transliteration.Publication Date: 2008 May 9 PMID: 18467569
Authors: Wang, L.
Journal: Science
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- Conservation biology. Into the wild: reintroduced animals face daunting odds.Publication Date: 2008 May 9 PMID: 18467568
Authors: Morell, V.
Journal: Science
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- Science and society. Talk nerdy to me.Publication Date: 2008 May 9 PMID: 18467567
Authors: Heyman, K.
Journal: Science
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- Planetary science. To touch the water of Mars and search for life's abode.Publication Date: 2008 May 9 PMID: 18467566
Authors: Kerr, R. A.
Journal: Science
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- Neurobiology. The roots of morality.Publication Date: 2008 May 9 PMID: 18467565
Authors: Miller, G.
Journal: Science
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- Intellectual property. Chinese province crafts pioneering law to thwart biopiracy.Publication Date: 2008 May 9 PMID: 18467564
Authors: Stone, R.
Journal: Science
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- Evolution in the schools. States push academic freedom bills.Publication Date: 2008 May 9 PMID: 18467563
Authors: Bhattacharjee, Y.
Journal: Science
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- Genomics. Genome speaks to transitional nature of monotremes.Publication Date: 2008 May 9 PMID: 18467562
Authors: Finkel, E.
Journal: Science
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- Archaeology. Ancient algae suggest sea route for first Americans.Publication Date: 2008 May 9 PMID: 18467561
Authors: Balter, M.
Journal: Science
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- U.S. science policy. Going from RAGS to riches is proving to be very difficult.Publication Date: 2008 May 9 PMID: 18467560
Authors: Mervis, J.
Journal: Science
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- AIDS and the next 25 years.Publication Date: 2008 May 9 PMID: 18467559
Authors: Bernstein, A.
Journal: Science
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- The Right and the Good: Distributive Justice and Neural Encoding of Equity and Efficiency.Publication Date: 2008 May 8 PMID: 18467558
Authors: Hsu, M. - Anen, C. - Quartz, S. R.
Journal: Science
Distributive justice concerns how individuals and societies distribute benefits and burdens in a just or moral manner. Combining distribution choices with functional magnetic resonance imaging (fMRI), we investigate the central problem of distributive justice: the tradeoff between equity and efficiency. We find that the putamen responds to efficiency, whereas the insula encodes inequity, and the caudate/septal subgenual region encodes a unified measure of efficiency and inequity (utility). Strikingly, individual differences in inequity aversion correlate with activity in inequity and utility regions. Against utilitarianism, our results support the deontological intuition that a sense of fairness is fundamental to distributive justice, but, as suggested by moral sentimentalists, is rooted in emotional processing. More generally, emotional responses related to norm violations may underlie individual differences in equity considerations and adherence to ethical rules.
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- An in Vivo Map of the Yeast Protein Interactome.Publication Date: 2008 May 8 PMID: 18467557
Authors: Tarassov, K. - Messier, V. - Landry, C. R. - Radinovic, S. - Molina, M. M. - Shames, I. - Malitskaya, Y. - Vogel, J. - Bussey, H. - Michnick, S. W.
Journal: Science
Protein interactions regulate the systems-level behavior of cells, thus, deciphering the structure and dynamics of protein interaction networks in their cellular context is a central goal in biology. We have performed a genome-wide in vivo screen for protein-protein interactions (PPIs) in Saccharomyces cerevisiae by means of a protein-fragment complementation assay (PCA). We identified 2,770 interactions among 1,124 endogenously expressed proteins. Comparison with previous studies confirms known interactions, but most are new, revealing a previously unknown sub-space of the yeast protein interactome. PCA detects structural and topological relationships between proteins, providing an 8-nanometer resolution map of dynamically interacting complexes in vivo and extended networks that provide insights into fundamental cellular processes, including cell polarization and autophagy, pathways that are evolutionarily conserved and central to both development and human health.
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- Anticipatory Behavior Within Microbial Genetic Networks.Publication Date: 2008 May 8 PMID: 18467556
Authors: Tagkopoulos, I. - Liu, Y. C. - Tavazoie, S.
Journal: Science
We question whether homeostasis alone adequately explains microbial responses to environmental stimuli, and explore the capacity of intra-cellular networks for predictive behavior in a fashion similar to metazoan nervous systems. We show that in silico biochemical networks, evolving randomly under precisely defined complex habitats, capture the dynamical, multi-dimensional structure of diverse environments by forming internal models that allow prediction of environmental change. We provide evidence for such anticipatory behavior by revealing striking correlations of Escherichia coli transcriptional responses to temperature and oxygen perturbations-precisely mirroring the co-variation of these parameters upon transitions between the outside world and the mammalian gastrointestinal-tract. We further show that these internal correlations reflect a true associative learning paradigm, since they show rapid de-coupling upon exposure to novel environments.
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- Slicing and Dicing for Small RNAs.Publication Date: 2008 May 8 PMID: 18467555
Authors: Birchler, J. A. - Kavi, H. H.
Journal: Science
A new type of small RNA and mode of gene regulation is discovered in fly and mammals.
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- A haptoglobin-hemoglobin receptor conveys innate immunity to Trypanosoma brucei in humans.Publication Date: 2008 May 2 PMID: 18451305
Authors: Vanhollebeke, B. - De Muylder, G. - Nielsen, M. J. - Pays, A. - Tebabi, P. - Dieu, M. - Raes, M. - Moestrup, S. K. - Pays, E.
Journal: Science
The protozoan parasite Trypanosoma brucei is lysed by apolipoprotein L-I, a component of human high-density lipoprotein (HDL) particles that are also characterized by the presence of haptoglobin-related protein. We report that this process is mediated by a parasite glycoprotein receptor, which binds the haptoglobin-hemoglobin complex with high affinity for the uptake and incorporation of heme into intracellular hemoproteins. In mice, this receptor was required for optimal parasite growth and the resistance of parasites to the oxidative burst by host macrophages. In humans, the trypanosome receptor also recognized the complex between hemoglobin and haptoglobin-related protein, which explains its ability to capture trypanolytic HDLs. Thus, in humans the presence of haptoglobin-related protein has diverted the function of the trypanosome haptoglobin-hemoglobin receptor to elicit innate host immunity against the parasite.
MeSH Categories: Amino Acid Sequence, Animals, Haptoglobins/metabolism, Hemoglobins/metabolism, Humans, Immunity, Natural, Lipoproteins, HDL/metabolism, Mice, Mice, Inbred Strains, Molecular Sequence Data, Receptors, Cell Surface/*immunology/metabolism, Trypanosoma brucei brucei/*immunology
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- Asymmetric tethering of flat and curved lipid membranes by a golgin.Publication Date: 2008 May 2 PMID: 18451304
Authors: Drin, G. - Morello, V. - Casella, J. F. - Gounon, P. - Antonny, B.
Journal: Science
Golgins, long stringlike proteins, tether cisternae and transport vesicles at the Golgi apparatus. We examined the attachment of golgin GMAP-210 to lipid membranes. GMAP-210 connected highly curved liposomes to flatter ones. This asymmetric tethering relied on motifs that sensed membrane curvature both in the N terminus of GMAP-210 and in ArfGAP1, which controlled the interaction of the C terminus of GMAP-210 with the small guanine nucleotide-binding protein Arf1. Because membrane curvature constantly changes during vesicular trafficking, this mode of tethering suggests a way to maintain the Golgi architecture without compromising membrane flow.
MeSH Categories: ADP-Ribosylation Factor 1/metabolism, Binding Sites, Cell Line, GTPase-Activating Proteins/metabolism, Golgi Apparatus/chemistry/metabolism, Hela Cells, Humans, Intracellular Membranes/*chemistry/metabolism, Liposomes, Membrane Lipids/*chemistry, Nuclear Proteins/*chemistry/metabolism, Recombinant Proteins/chemistry/metabolism
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- Phosphorylation by p38 MAPK as an alternative pathway for GSK3beta inactivation.Publication Date: 2008 May 2 PMID: 18451303
Authors: Thornton, T. M. - Pedraza-Alva, G. - Deng, B. - Wood, C. D. - Aronshtam, A. - Clements, J. L. - Sabio, G. - Davis, R. J. - Matthews, D. E. - Doble, B. - Rincon, M.
Journal: Science
Glycogen synthase kinase 3beta (GSK3beta) is involved in metabolism, neurodegeneration, and cancer. Inhibition of GSK3beta activity is the primary mechanism that regulates this widely expressed active kinase. Although the protein kinase Akt inhibits GSK3beta by phosphorylation at the N terminus, preventing Akt-mediated phosphorylation does not affect the cell-survival pathway activated through the GSK3beta substrate beta-catenin. Here, we show that p38 mitogen-activated protein kinase (MAPK) also inactivates GSK3beta by direct phosphorylation at its C terminus, and this inactivation can lead to an accumulation of beta-catenin. p38 MAPK-mediated phosphorylation of GSK3beta occurs primarily in the brain and thymocytes. Activation of beta-catenin-mediated signaling through GSK3beta inhibition provides a potential mechanism for p38 MAPK-mediated survival in specific tissues.
MeSH Categories: Animals, Brain/enzymology, Glycogen Synthase Kinase 3/*antagonists & inhibitors/immunology/metabolism, Humans, Mice, Phosphorylation, Protein Kinase Inhibitors/*metabolism, Proto-Oncogene Proteins c-akt/metabolism, Serine/metabolism, Thymus Gland/cytology/enzymology, beta Catenin/metabolism, p38 Mitogen-Activated Protein Kinases/*metabolism
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- In vivo imaging of membrane-associated glycans in developing zebrafish.Publication Date: 2008 May 2 PMID: 18451302
Authors: Laughlin, S. T. - Baskin, J. M. - Amacher, S. L. - Bertozzi, C. R.
Journal: Science
Glycans are attractive targets for molecular imaging but have been inaccessible because of their incompatibility with genetically encoded reporters. We demonstrated the noninvasive imaging of glycans in live developing zebrafish, using a chemical reporter strategy. Zebrafish embryos were treated with an unnatural sugar to metabolically label their cell-surface glycans with azides. Subsequently, the embryos were reacted with fluorophore conjugates by means of copper-free click chemistry, enabling the visualization of glycans in vivo at subcellular resolution during development. At 60 hours after fertilization, we observed an increase in de novo glycan biosynthesis in the jaw region, pectoral fins, and olfactory organs. Using a multicolor detection strategy, we performed a spatiotemporal analysis of glycan expression and trafficking and identified patterns that would be undetectable with conventional molecular imaging approaches.
MeSH Categories: Acetylgalactosamine/chemistry, Affinity Labels, Animals, Cell Line, Cell Membrane/*chemistry, Fluorescent Dyes/chemistry, Polysaccharides/*analysis/biosynthesis, *Zebrafish/embryology
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- A general model for food web structure.Publication Date: 2008 May 2 PMID: 18451301
Authors: Allesina, S. - Alonso, D. - Pascual, M.
Journal: Science
A central problem in ecology is determining the processes that shape the complex networks known as food webs formed by species and their feeding relationships. The topology of these networks is a major determinant of ecosystems' dynamics and is ultimately responsible for their responses to human impacts. Several simple models have been proposed for the intricate food webs observed in nature. We show that the three main models proposed so far fail to fully replicate the empirical data, and we develop a likelihood-based approach for the direct comparison of alternative models based on the full structure of the network. Results drive a new model that is able to generate all the empirical data sets and to do so with the highest likelihood.
MeSH Categories: *Food Chain, Likelihood Functions, *Models, Biological
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- Expanding oxygen-minimum zones in the tropical oceans.Publication Date: 2008 May 2 PMID: 18451300
Authors: Stramma, L. - Johnson, G. C. - Sprintall, J. - Mohrholz, V.
Journal: Science
Oxygen-poor waters occupy large volumes of the intermediate-depth eastern tropical oceans. Oxygen-poor conditions have far-reaching impacts on ecosystems because important mobile macroorganisms avoid or cannot survive in hypoxic zones. Climate models predict declines in oceanic dissolved oxygen produced by global warming. We constructed 50-year time series of dissolved-oxygen concentration for select tropical oceanic regions by augmenting a historical database with recent measurements. These time series reveal vertical expansion of the intermediate-depth low-oxygen zones in the eastern tropical Atlantic and the equatorial Pacific during the past 50 years. The oxygen decrease in the 300- to 700-m layer is 0.09 to 0.34 micromoles per kilogram per year. Reduced oxygen levels may have dramatic consequences for ecosystems and coastal economies.
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- Marine polyphosphate: a key player in geologic phosphorus sequestration.Publication Date: 2008 May 2 PMID: 18451299
Authors: Diaz, J. - Ingall, E. - Benitez-Nelson, C. - Paterson, D. - de Jonge, M. D. - McNulty, I. - Brandes, J. A.
Journal: Science
The in situ or authigenic formation of calcium phosphate minerals in marine sediments is a major sink for the vital nutrient phosphorus. However, because typical sediment chemistry is not kinetically conducive to the precipitation of these minerals, the mechanism behind their formation has remained a fundamental mystery. Here, we present evidence from high-sensitivity x-ray and electrodialysis techniques to describe a mechanism by which abundant diatom-derived polyphosphates play a critical role in the formation of calcium phosphate minerals in marine sediments. This mechanism can explain the puzzlingly dispersed distribution of calcium phosphate minerals observed in marine sediments worldwide.
MeSH Categories: Apatites/chemistry, Biomass, Diatoms/*chemistry, Geologic Sediments, Microscopy, Fluorescence, Pacific Ocean, Phosphorus/*chemistry, Polyphosphates/*chemistry, Spectrometry, Fluorescence
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- Practical synthesis of prostratin, DPP, and their analogs, adjuvant leads against latent HIV.Publication Date: 2008 May 2 PMID: 18451298
Authors: Wender, P. A. - Kee, J. M. - Warrington, J. M.
Journal: Science
Although antiretroviral therapies have been effective in decreasing active viral loads in AIDS patients, the persistence of latent viral reservoirs prevents eradication of the virus. Prostratin and DPP (12-deoxyphorbol-13-phenylacetate) activate the latent virus and thus represent promising adjuvants for antiviral therapy. Their limited supply and the challenges of accessing related structures have, however, impeded therapeutic development and the search for clinically superior analogs. Here we report a practical synthesis of prostratin and DPP starting from phorbol or crotophorbolone, agents readily available from renewable sources, including a biodiesel candidate. This synthesis reliably supplies gram quantities of the therapeutically promising natural products, hitherto available only in low and variable amounts from natural sources, and opens access to a variety of new analogs.
MeSH Categories: Anti-HIV Agents/*chemical synthesis, Chemotherapy, Adjuvant, HIV-1/*drug effects/physiology, Humans, Models, Molecular, Phorbol Esters/*chemical synthesis, Phorbols/chemistry, Viral Load, Virus Latency/drug effects
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- Strong interactions in multimode random lasers.Publication Date: 2008 May 2 PMID: 18451297
Authors: Tureci, H. E. - Ge, L. - Rotter, S. - Stone, A. D.
Journal: Science
Unlike conventional lasers, diffusive random lasers (DRLs) have no resonator to trap light and no high-Q resonances to support lasing. Because of this lack of sharp resonances, the DRL has presented a challenge to conventional laser theory. We present a theory able to treat the DRL rigorously and provide results on the lasing spectra, internal fields, and output intensities of DRLs. Typically DRLs are highly multimode lasers, emitting light at a number of wavelengths. We show that the modal interactions through the gain medium in such lasers are extremely strong and lead to a uniformly spaced frequency spectrum, in agreement with recent experimental observations.
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- Coherent control of decoherence.Publication Date: 2008 May 2 PMID: 18451296
Authors: Branderhorst, M. P. - Londero, P. - Wasylczyk, P. - Brif, C. - Kosut, R. L. - Rabitz, H. - Walmsley, I. A.
Journal: Science
Manipulation of quantum interference requires that the system under control remains coherent, avoiding (or at least postponing) the phase randomization that can ensue from coupling to an uncontrolled environment. We show that closed-loop coherent control can be used to mitigate the rate of quantum dephasing in a gas-phase ensemble of potassium dimers (K2), which acts as a model system for testing the general concepts of controlling decoherence. Specifically, we adaptively shaped the light pulse used to prepare a vibrational wave packet in electronically excited K2, with the amplitude of quantum beats in the fluorescence signal used as an easily measured surrogate for the purpose of optimizing coherence. The optimal pulse increased the beat amplitude from below the noise level to well above it, and thereby increased the coherence life time as compared with the beats produced by a transform-limited pulse. Closed-loop methods can thus effectively identify states that are robust against dephasing without any previous information about the system-environment interaction.
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- A specialized forebrain circuit for vocal babbling in the juvenile songbird.Publication Date: 2008 May 2 PMID: 18451295
Authors: Aronov, D. - Andalman, A. S. - Fee, M. S.
Journal: Science
Young animals engage in variable exploratory behaviors essential for the development of neural circuitry and adult motor control, yet the neural basis of these behaviors is largely unknown. Juvenile songbirds produce subsong-a succession of primitive vocalizations akin to human babbling. We found that subsong production in zebra finches does not require HVC (high vocal center), a key premotor area for singing in adult birds, but does require LMAN (lateral magnocellular nucleus of the nidopallium), a forebrain nucleus involved in learning but not in adult singing. During babbling, neurons in LMAN exhibited premotor correlations to vocal output on a fast time scale. Thus, juvenile singing is driven by a circuit distinct from that which produces the adult behavior-a separation possibly general to other developing motor systems.
MeSH Categories: Animals, Finches/growth & development/*physiology, Neural Pathways/physiology, Neurons/physiology, Prosencephalon/*physiology, Vocalization, Animal/*physiology
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- Fire-derived charcoal causes loss of forest humus.Publication Date: 2008 May 2 PMID: 18451294
Authors: Wardle, D. A. - Nilsson, M. C. - Zackrisson, O.
Journal: Science
Fire is a global driver of carbon storage and converts a substantial proportion of plant biomass to black carbon (for example, charcoal), which remains in the soil for thousands of years. Black carbon is therefore often proposed as an important long-term sink of soil carbon. We ran a 10-year experiment in each of three boreal forest stands to show that fire-derived charcoal promotes loss of forest humus and that this is associated with enhancement of microbial activity by charcoal. This result shows that charcoal-induced losses of belowground carbon in forests can partially offset the benefits of charcoal as a long-term carbon sink.
MeSH Categories: Biomass, Charcoal/chemistry, Ecosystem, *Fires, *Soil, Soil Microbiology, Soot/chemistry, Sweden, *Trees
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- Structure and dynamics of Earth's lower mantle.Publication Date: 2008 May 2 PMID: 18451293
Authors: Garnero, E. J. - McNamara, A. K.
Journal: Science
Processes within the lowest several hundred kilometers of Earth's rocky mantle play a critical role in the evolution of the planet. Understanding Earth's lower mantle requires putting recent seismic and mineral physics discoveries into a self-consistent, geodynamically feasible context. Two nearly antipodal large low-shear-velocity provinces in the deep mantle likely represent chemically distinct and denser material. High-resolution seismological studies have revealed laterally varying seismic velocity discontinuities in the deepest few hundred kilometers, consistent with a phase transition from perovskite to post-perovskite. In the deepest tens of kilometers of the mantle, isolated pockets of ultralow seismic velocities may denote Earth's deepest magma chamber.
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- Molecular biology. The paradox of silent heterochromatin.Publication Date: 2008 May 2 PMID: 18451292
Authors: Djupedal, I. - Ekwall, K.
Journal: Science
MeSH Categories: Cell Cycle/genetics, Heterochromatin/*physiology, Models, Biological, RNA Interference, RNA Polymerase II/metabolism, RNA, Fungal/physiology, Schizosaccharomyces/genetics/physiology, Transcription, Genetic
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- Physics. A unified picture of laser physics.Publication Date: 2008 May 2 PMID: 18451291
Authors: Bravo-Abad, J. - Soljacic, M.
Journal: Science
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- Ecology. How reefs respond to mass coral spawning.Publication Date: 2008 May 2 PMID: 18451290
Authors: Guest, J.
Journal: Science
MeSH Categories: Animals, Anthozoa/growth & development/*physiology, Ecology, Ecosystem, Geologic Sediments, Reproduction
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- Chemistry. Synchronized self-assembly.Publication Date: 2008 May 2 PMID: 18451289
Authors: Moore, J. S. - Kraft, M. L.
Journal: Science
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- Immunology. How frustration leads to inflammation.Publication Date: 2008 May 2 PMID: 18451288
Authors: O'Neill, L. A.
Journal: Science
MeSH Categories: Air Pollutants/*toxicity, Animals, Asbestos/immunology/toxicity, Humans, Inflammation/chemically induced/complications/*etiology, Inflammation Mediators/immunology, Mice
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- Engineering. High-performance transistors by design.Publication Date: 2008 May 2 PMID: 18451287
Authors: Guo, X. - Silva, S. R.
Journal: Science
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- Economics. Linking natural resources to slow growth and more conflict.Publication Date: 2008 May 2 PMID: 18451286
Authors: Brunnschweiler, C. N. - Bulte, E. H.
Journal: Science
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- Comment on "Long-lived giant number fluctuations in a swarming granular nematic".Publication Date: 2008 May 2 PMID: 18451285
Authors: Aranson, I. S. - Snezhko, A. - Olafsen, J. S. - Urbach, J. S.
Journal: Science
Narayan et al. (Reports, 6 July 2007, p. 105) reported giant number fluctuations attributed to curvature-driven active currents specific for nonequilibrium nematic systems. We present data demonstrating that similar results can be found in systems of spherical particles due either to inelastic clustering or persistent density inhomogeneity, suggesting two alternative explanations for their results.
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- Coarse-resolution models only partly cloudy.Publication Date: 2008 May 2 PMID: 18451284
Authors: Sperber, K. R. - Slingo, J. M. - Waliser, D. E. - Inness, P. M.
Journal: Science
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- Ensuring food security.Publication Date: 2008 May 2 PMID: 18451283
Authors: Wojtkowski, P.
Journal: Science
MeSH Categories: Agriculture, Crops, Agricultural, Developing Countries, *Food Supply, Humans, *Security Measures
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- American Association of Physical Anthropologists meeting. Snapshots from the meeting.Publication Date: 2008 May 2 PMID: 18451282
Authors: Gibbons, A. - Culotta, E.
Journal: Science
MeSH Categories: Animals, *Anthropology, Physical, Evolution, Flight, Animal, Hominidae, Humans, Locomotion, Speech
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- American Association of Physical Anthropologists meeting. Australopithecus not much of a nutcracker.Publication Date: 2008 May 2 PMID: 18451281
Authors: Gibbons, A.
Journal: Science
MeSH Categories: Animals, Diet, Evolution, *Hominidae/anatomy & histology/classification/physiology, Humans, Jaw/anatomy & histology, Molar/anatomy & histology, Paleodontology, Tooth Attrition
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- American Association of Physical Anthropologists meeting. Tuberculosis jumped from humans to cows, not vice versa.Publication Date: 2008 May 2 PMID: 18451280
Authors: Gibbons, A.
Journal: Science
MeSH Categories: Animals, Cattle, DNA, Bacterial, Evolution, Molecular, History, Ancient, Humans, *Mycobacterium bovis/genetics, *Mycobacterium tuberculosis/genetics, Tuberculosis/*history/transmission/veterinary, Tuberculosis, Bovine/*history/microbiology, Zoonoses/history
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- Gene therapy. Two teams report progress in reversing loss of sight.Publication Date: 2008 May 2 PMID: 18451279
Authors: Kaiser, J.
Journal: Science
MeSH Categories: Adolescent, Adult, Animals, Blindness/genetics/*therapy, Carrier Proteins/genetics, Child, Clinical Trials as Topic, Dogs, Eye Proteins/genetics, *Gene Therapy, Humans, Infant, Male, Retinal Diseases/genetics/*therapy
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- Neil Turok profile. An African showcase for math studies.Publication Date: 2008 May 2 PMID: 18451278
Authors: Koenig, R.
Journal: Science
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- Neil Turok profile. Wishing for an African Einstein.Publication Date: 2008 May 2 PMID: 18451277
Authors: Clery, D.
Journal: Science
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- Medicine. A bumper crop of conflicts.Publication Date: 2008 May 2 PMID: 18451276
Authors: Marshall, E.
Journal: Science
MeSH Categories: Clinical Trials as Topic, *Conflict of Interest, Humans, Lung Neoplasms/*diagnosis/etiology, *Mass Screening/economics, Patents as Topic, Research Personnel, *Smoking/adverse effects, Tobacco Industry, Tomography, X-Ray Computed/economics
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- Medicine. A bruising battle over lung scans.Publication Date: 2008 May 2 PMID: 18451275
Authors: Marshall, E.
Journal: Science
MeSH Categories: Adult, Clinical Trials as Topic/*economics, Cost-Benefit Analysis, Early Diagnosis, Humans, Lung Neoplasms/*diagnosis/economics/therapy, *Mass Screening/economics, National Cancer Institute (U.S.), Randomized Controlled Trials as Topic, Smoking, Tomography, Spiral Computed/*economics, United States
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- Paleoecology. Fossils help figure out food webs old and new.Publication Date: 2008 May 2 PMID: 18451274
Authors: Pennisi, E.
Journal: Science
MeSH Categories: Animals, Canada, China, Ecosystem, Evolution, *Food Chain, *Fossils, Plants
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- Tropical diseases. Dispute clouds the future of U.S. Naval Lab in Indonesia.Publication Date: 2008 May 2 PMID: 18451273
Authors: Normile, D.
Journal: Science
MeSH Categories: *Academies and Institutes, *Biomedical Research, *Communicable Diseases, Forecasting, Health Facility Closure, Indonesia, Influenza A Virus, H5N1 Subtype, International Cooperation, *Laboratories, Military Medicine, *Tropical Medicine, United States
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- Ecology. Yosemite: protected but not preserved.Publication Date: 2008 May 2 PMID: 18451272
Authors: Morell, V.
Journal: Science
MeSH Categories: Animals, California, *Conservation of Natural Resources, Deer, Ecosystem, Humans, Oenothera biennis, Population Dynamics, *Quercus
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- Louise Slaughter interview. How to get a genetic protection law through Congress? Keep trying. Interview by Jennifer Couzin.Publication Date: 2008 May 2 PMID: 18451271
Authors: Slaughter, L.
Journal: Science
MeSH Categories: Employment/legislation & jurisprudence, Genetic Privacy/*legislation & jurisprudence, Genetic Screening/legislation & jurisprudence, Genome, Human, Humans, *Insurance Selection Bias, Prejudice
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- Global warming. Mother nature cools the greenhouse, but hotter times still lie ahead.Publication Date: 2008 May 2 PMID: 18451270
Authors: Kerr, R. A.
Journal: Science
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- Endangered species. Spotted owl recovery plan flawed, review panel finds.Publication Date: 2008 May 2 PMID: 18451269
Authors: Stokstad, E.
Journal: Science
MeSH Categories: Advisory Committees, Animals, *Conservation of Natural Resources/legislation & jurisprudence, Public Policy, *Strigiformes, United States
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- Misbegotten preemptions.Publication Date: 2008 May 2 PMID: 18451268
Authors: Kennedy, D.
Journal: Science
MeSH Categories: Commerce/legislation & jurisprudence, Drug Approval, Federal Government, Liability, Legal, Public Policy, State Government, United States, United States Food and Drug Administration/*legislation & jurisprudence
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- The Serine Protease TMPRSS6 Is Required to Sense Iron Deficiency.Publication Date: 2008 May 1 PMID: 18451267
Authors: Du, X. - She, E. - Gelbart, T. - Truksa, J. - Lee, P. - Xia, Y. - Khovananth, K. - Mudd, S. - Mann, N. - Moresco, E. M. - Beutler, E. - Beutler, B.
Journal: Science
Hepcidin, a liver-derived protein that restricts enteric iron absorption, is the key regulator of body iron content. Several proteins induce expression of the hepcidin-encoding gene Hamp in response to infection or high levels of iron. However, mechanism(s) of Hamp suppression during iron depletion are poorly understood. Here we describe mask, a recessive, chemically induced mutant mouse phenotype, characterized by progressive loss of body but not facial hair and microcytic anemia. The mask phenotype results from reduced absorption of dietary iron caused by high levels of hepcidin, and is due to a splicing defect in the transmembrane serine protease 6 gene Tmprss6. Overexpression of normal TMPRSS6 protein suppresses activation of the Hamp promoter, and the TMPRSS6 cytoplasmic domain mediates Hamp suppression via proximal promoter element(s). TMPRSS6 is an essential component of a pathway that detects iron deficiency and blocks Hamp transcription, permitting enhanced dietary iron absorption.
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- The Transcriptional Landscape of the Yeast Genome Defined by RNA Sequencing.Publication Date: 2008 May 1 PMID: 18451266
Authors: Nagalakshmi, U. - Wang, Z. - Waern, K. - Shou, C. - Raha, D. - Gerstein, M. - Snyder, M.
Journal: Science
The identification of untranslated regions (UTRs), introns, and coding regions within an organism remains challenging. We developed a quantitative sequencing-based method for mapping transcribed regions called RNA-Seq in which cDNA fragments are subjected to high throughput sequencing and mapped to the genome. We applied RNA-Seq to generate a high-resolution transcriptome map of the yeast genome and demonstrated that most (74.5%) of the nonrepetitive sequence of the yeast genome is transcribed. We confirmed many known and predicted introns and demonstrated that others are not actively used. Alternative initiation codons and upstream open reading frames were also identified for many yeast genes. We also found unexpected 3' end heterogeneity and the presence of many overlapping genes. These results indicate that the yeast transcriptome is more complex than previously appreciated.
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- A Polymorphism Within the G6PC2 Gene Is Associated with Fasting Plasma Glucose Levels.Publication Date: 2008 May 1 PMID: 18451265
Authors: Bouatia-Naji, N. - Rocheleau, G. - Van Lommel, L. - Lemaire, K. - Schuit, F. - Cavalcanti-Proenca, C. - Marchand, M. - Hartikainen, A. L. - Sovio, U. - De Graeve, F. - Rung, J. - Vaxillaire, M. - Tichet, J. - Marre, M. - Balkau, B. - Weill, J. - Elliott, P. - Jarvelin, M. R. - Meyre, D. - Polychronakos, C. - Dina, C. - Sladek, R. - Froguel, P.
Journal: Science
Several studies have shown that healthy individuals with fasting plasma glucose (FPG) levels at the high end of the normal range have a higher risk of mortality. To identify genetic determinants that contribute to inter-individual variation in FPG, we tested 392,935 single nucleotide polymorphisms (SNPs) in 654 normoglycemic subjects for association with FPG and we replicated the most strongly associated SNP (rs560887, p = 4 x 10(-7)) in 9,353 subjects. SNP rs560887 maps to intron 3 of the G6PC2 gene, which encodes glucose-6-phosphatase catalytic subunit-related protein (also known as IGRP), a protein selectively expressed in pancreatic islets. This SNP was associated with FPG (beta = -0.06 mmol/l per A-allele, combined p = 4 x 10(-23)) and with pancreatic beta-cell function (Homa-B model, combined p = 3 x 10(-13)) in three populations; however it was not associated with type 2 diabetes risk. We speculate that G6PC2/IGRP regulates FPG by modulating the set-point for glucose-stimulated insulin secretion in pancreatic beta cells.
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- Dislocation-Driven Nanowire Growth and Eshelby Twist.Publication Date: 2008 May 1 PMID: 18451264
Authors: Bierman, M. J. - Lau, Y. K. - Kvit, A. V. - Schmitt, A. L. - Jin, S.
Journal: Science
Hierarchical nanostructures of lead sulfide nanowires resembling pine trees were synthesized via chemical vapor deposition. Structural characterization reveals a screw-like dislocation in the nanowire trunks with helically rotating epitaxial branch nanowires. It is suggested that the screw component of an axial dislocation provides the self-perpetuating steps to enable one-dimensional crystal growth, in contrast to mechanisms that require metal catalysts. The rotating trunks and branches are the consequence of the Eshelby twist of screw dislocations with a dislocation Burgers vector along <110> directions with an estimated magnitude of 6 +/- 2 A for the screw component. The results confirm the Eshelby theory of dislocations and the proposed nanowire growth mechanism could be general to many materials.
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- Plastin 3 is a protective modifier of autosomal recessive spinal muscular atrophy.Publication Date: 2008 Apr 25 PMID: 18440926
Authors: Oprea, G. E. - Krober, S. - McWhorter, M. L. - Rossoll, W. - Muller, S. - Krawczak, M. - Bassell, G. J. - Beattie, C. E. - Wirth, B.
Journal: Science
Homozygous deletion of the survival motor neuron 1 gene (SMN1) causes spinal muscular atrophy (SMA), the most frequent genetic cause of early childhood lethality. In rare instances, however, individuals are asymptomatic despite carrying the same SMN1 mutations as their affected siblings, thereby suggesting the influence of modifier genes. We discovered that unaffected SMN1-deleted females exhibit significantly higher expression of plastin 3 (PLS3) than their SMA-affected counterparts. We demonstrated that PLS3 is important for axonogenesis through increasing the F-actin level. Overexpression of PLS3 rescued the axon length and outgrowth defects associated with SMN down-regulation in motor neurons of SMA mouse embryos and in zebrafish. Our study suggests that defects in axonogenesis are the major cause of SMA, thereby opening new therapeutic options for SMA and similar neuromuscular diseases.
MeSH Categories: Actins/blood/*genetics/*metabolism, Animals, Axons/metabolism/*physiology/ultrastructure, Cell Differentiation, Cell Line, Cyclic AMP Response Element-Binding Protein/genetics/metabolism, Female, Gene Expression, Growth Cones/metabolism/ultrastructure, Humans, Male, Mice, Muscular Atrophy, Spinal/*genetics, Nerve Tissue Proteins/genetics/metabolism, Pedigree, Phosphoproteins/blood/*genetics/*metabolism, RNA-Binding Proteins/genetics/metabolism, Spinal Cord/metabolism, Transcription, Genetic, Zebrafish/embryology/genetics
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- Human-induced Arctic moistening.Publication Date: 2008 Apr 25 PMID: 18440925
Authors: Min, S. K. - Zhang, X. - Zwiers, F.
Journal: Science
The Arctic and northern subpolar regions are critical for climate change. Ice-albedo feedback amplifies warming in the Arctic, and fluctuations of regional fresh water inflow to the Arctic Ocean modulate the deep ocean circulation and thus exert a strong global influence. By comparing observations to simulations from 22 coupled climate models, we find influence from anthropogenic greenhouse gases and sulfate aerosols in the space-time pattern of precipitation change over high-latitude land areas north of 55 degrees N during the second half of the 20th century. The human-induced Arctic moistening is consistent with observed increases in Arctic river discharge and freshening of Arctic water masses. This result provides new evidence that human activity has contributed to Arctic hydrological change.
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- Near-field plates: subdiffraction focusing with patterned surfaces.Publication Date: 2008 Apr 25 PMID: 18440924
Authors: Grbic, A. - Jiang, L. - Merlin, R.
Journal: Science
Using a patterned, grating-like plate to control the electromagnetic near field, we demonstrate focusing well beyond the diffraction limit at approximately 1 gigahertz. The near-field plate consists of only capacitive elements and focuses microwaves emanating from a cylindrical source to a spot of size approximately lambda/20 (half-power beamwidth), where lambda is the free-space wavelength. These plates will find application in antennas, beam-shaping devices, nonradiative wireless power-transfer systems, microscopy, and lithography.
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- Sign Change of Poisson's Ratio for Carbon Nanotube Sheets.Publication Date: 2008 Apr 25 PMID: 18440923
Authors: Hall, L. J. - Coluci, V. R. - Galvao, D. S. - Kozlov, M. E. - Zhang, M. - Dantas, S. O. - Baughman, R. H.
Journal: Science
Most materials shrink laterally like a rubber band when stretched, so their Poisson's ratios are positive. Likewise, most materials contract in all directions when hydrostatically compressed and decrease density when stretched, so they have positive linear compressibilities. We found that the in-plane Poisson's ratio of carbon nanotube sheets (buckypaper) can be tuned from positive to negative by mixing single-walled and multiwalled nanotubes. Density-normalized sheet toughness, strength, and modulus were substantially increased by this mixing. A simple model predicts the sign and magnitude of Poisson's ratio for buckypaper from the relative ease of nanofiber bending and stretch, and explains why the Poisson's ratios of ordinary writing paper are positive and much larger. Theory also explains why the negative in-plane Poisson's ratio is associated with a large positive Poisson's ratio for the sheet thickness, and predicts that hydrostatic compression can produce biaxial sheet expansion. This tunability of Poisson's ratio can be exploited in the design of sheet-derived composites, artificial muscles, gaskets, and chemical and mechanical sensors.
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- Encoding gender and individual information in the mouse vomeronasal organ.Publication Date: 2008 Apr 25 PMID: 18436787
Authors: He, J. - Ma, L. - Kim, S. - Nakai, J. - Yu, C. R.
Journal: Science
The mammalian vomeronasal organ detects complex chemical signals that convey information about gender, strain, and the social and reproductive status of an individual. How these signals are encoded is poorly understood. We developed transgenic mice expressing the calcium indicator G-CaMP2 and analyzed population responses of vomeronasal neurons to urine from individual animals. A substantial portion of cells was activated by either male or female urine, but only a small population of cells responded exclusively to gender-specific cues shared across strains and individuals. Female cues activated more cells and were subject to more complex hormonal regulations than male cues. In contrast to gender, strain and individual information was encoded by the combinatorial activation of neurons such that urine from different individuals activated distinctive cell populations.
MeSH Categories: Animals, Behavior, Animal, Calcium/metabolism, Cluster Analysis, Cues, Female, Male, Mice, Mice, Inbred C57BL, Mice, Inbred CBA, Neurons, Afferent/*physiology, *Pheromones, Principal Component Analysis, Receptors, Pheromone/physiology, Sex Characteristics, *Urine/chemistry, Vomeronasal Organ/cytology/*physiology
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- Vaccinia virus uses macropinocytosis and apoptotic mimicry to enter host cells.Publication Date: 2008 Apr 25 PMID: 18436786
Authors: Mercer, J. - Helenius, A.
Journal: Science
Viruses employ many different strategies to enter host cells. Vaccinia virus, a prototype poxvirus, enters cells in a pH-dependent fashion. Live cell imaging showed that fluorescent virus particles associated with and moved along filopodia to the cell body, where they were internalized after inducing the extrusion of large transient membrane blebs. p21-activated kinase 1 (PAK1) was activated by the virus, and the endocytic process had the general characteristics of macropinocytosis. The induction of blebs, the endocytic event, and infection were all critically dependent on the presence of exposed phosphatidylserine in the viral membrane, which suggests that vaccinia virus uses apoptotic mimicry to enter cells.
MeSH Categories: Actins/metabolism, Animals, *Apoptosis, Cell Membrane/*metabolism/ultrastructure, Humans, Phosphatidylserines/*metabolism, *Pinocytosis, RNA Interference, Vaccinia virus/*physiology, *Virus Internalization, p21-Activated Kinases/genetics/metabolism, rac1 GTP-Binding Protein/metabolism
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- Role of C. elegans TAT-1 protein in maintaining plasma membrane phosphatidylserine asymmetry.Publication Date: 2008 Apr 25 PMID: 18436785
Authors: Darland-Ransom, M. - Wang, X. - Sun, C. L. - Mapes, J. - Gengyo-Ando, K. - Mitani, S. - Xue, D.
Journal: Science
The asymmetrical distribution of phospholipids on the plasma membrane is critical for maintaining cell integrity and physiology and for regulating intracellular signaling and important cellular events such as clearance of apoptotic cells. How phospholipid asymmetry is established and maintained is not fully understood. We report that the Caenorhabditis elegans P-type adenosine triphosphatase homolog, TAT-1, is critical for maintaining cell surface asymmetry of phosphatidylserine (PS). In animals deficient in tat-1, PS is abnormally exposed on the cell surface, and normally living cells are randomly lost through a mechanism dependent on PSR-1, a PS-recognizing phagocyte receptor, and CED-1, which contributes to recognition and engulfment of apoptotic cells. Thus, tat-1 appears to function in preventing appearance of PS in the outer leaflet of plasma membrane, and ectopic exposure of PS on the cell surface may result in removal of living cells by neighboring phagocytes.
MeSH Categories: Animals, Animals, Genetically Modified, Apoptosis, Caenorhabditis elegans/cytology/genetics/*metabolism, Caenorhabditis elegans Proteins/genetics/*metabolism, Cell Membrane/*metabolism, Germ Cells/cytology/metabolism, Muscle Cells/cytology/metabolism, Neurons/cytology/metabolism, Phagocytosis, Phosphatidylserines/*metabolism, Phospholipid Transfer Proteins/genetics/*metabolism, RNA Interference, Recombinant Fusion Proteins/metabolism
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- Efficient inhibition of the Alzheimer's disease beta-secretase by membrane targeting.Publication Date: 2008 Apr 25 PMID: 18436784
Authors: Rajendran, L. - Schneider, A. - Schlechtingen, G. - Weidlich, S. - Ries, J. - Braxmeier, T. - Schwille, P. - Schulz, J. B. - Schroeder, C. - Simons, M. - Jennings, G. - Knolker, H. J. - Simons, K.
Journal: Science
beta-Secretase plays a critical role in beta-amyloid formation and thus provides a therapeutic target for Alzheimer's disease. Inhibitor design has usually focused on active-site binding, neglecting the subcellular localization of active enzyme. We have addressed this issue by synthesizing a membrane-anchored version of a beta-secretase transition-state inhibitor by linking it to a sterol moiety. Thus, we targeted the inhibitor to active beta-secretase found in endosomes and also reduced the dimensionality of the inhibitor, increasing its local membrane concentration. This inhibitor reduced enzyme activity much more efficiently than did the free inhibitor in cultured cells and in vivo. In addition to effectively targeting beta-secretase, this strategy could also be used in designing potent drugs against other membrane protein targets.
MeSH Categories: Alzheimer Disease/drug therapy/enzymology, Amyloid Precursor Protein Secretases/*antagonists & inhibitors/metabolism, Amyloid beta-Protein/metabolism, Amyloid beta-Protein Precursor/metabolism, Animals, Animals, Genetically Modified, Drosophila/genetics, Drug Delivery Systems, *Drug Design, Endocytosis, Endosomes/*enzymology, Hela Cells, Humans, Intracellular Membranes/metabolism, Membrane Microdomains/enzymology, Mice, Peptides/chemistry/metabolism/*pharmacology, Protease Inhibitors/chemical synthesis/chemistry/metabolism/*pharmacology, *Sterols
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- Synchronizing rock clocks of Earth history.Publication Date: 2008 Apr 25 PMID: 18436783
Authors: Kuiper, K. F. - Deino, A. - Hilgen, F. J. - Krijgsman, W. - Renne, P. R. - Wijbrans, J. R.
Journal: Science
Calibration of the geological time scale is achieved by independent radioisotopic and astronomical dating, but these techniques yield discrepancies of approximately 1.0% or more, limiting our ability to reconstruct Earth history. To overcome this fundamental setback, we compared astronomical and 40Ar/39Ar ages of tephras in marine deposits in Morocco to calibrate the age of Fish Canyon sanidine, the most widely used standard in 40Ar/39Ar geochronology. This calibration results in a more precise older age of 28.201 +/- 0.046 million years ago (Ma) and reduces the 40Ar/39Ar method's absolute uncertainty from approximately 2.5 to 0.25%. In addition, this calibration provides tight constraints for the astronomical tuning of pre-Neogene successions, resulting in a mutually consistent age of approximately 65.95 Ma for the Cretaceous/Tertiary boundary.
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- Molecular phylogenetics of mastodon and Tyrannosaurus rex.Publication Date: 2008 Apr 25 PMID: 18436782
Authors: Organ, C. L. - Schweitzer, M. H. - Zheng, W. - Freimark, L. M. - Cantley, L. C. - Asara, J. M.
Journal: Science
We report a molecular phylogeny for a nonavian dinosaur, extending our knowledge of trait evolution within nonavian dinosaurs into the macromolecular level of biological organization. Fragments of collagen alpha1(I) and alpha2(I) proteins extracted from fossil bones of Tyrannosaurus rex and Mammut americanum (mastodon) were analyzed with a variety of phylogenetic methods. Despite missing sequence data, the mastodon groups with elephant and the T. rex groups with birds, consistent with predictions based on genetic and morphological data for mastodon and on morphological data for T. rex. Our findings suggest that molecular data from long-extinct organisms may have the potential for resolving relationships at critical areas in the vertebrate evolutionary tree that have, so far, been phylogenetically intractable.
MeSH Categories: Amino Acid Sequence, Animals, Bayes Theorem, Birds/classification/genetics, Bone and Bones, Collagen Type I/*chemistry/genetics, Dinosaurs/anatomy & histology/*classification/*genetics, Elephants/anatomy & histology/*classification/*genetics, Evolution, Fossils, Likelihood Functions, Molecular Sequence Data, *Phylogeny, Sequence Alignment
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- From genotype to phenotype: systems biology meets natural variation.Publication Date: 2008 Apr 25 PMID: 18436781
Authors: Benfey, P. N. - Mitchell-Olds, T.
Journal: Science
The promise that came with genome sequencing was that we would soon know what genes do, particularly genes involved in human diseases and those of importance to agriculture. We now have the full genomic sequence of human, chimpanzee, mouse, chicken, dog, worm, fly, rice, and cress, as well as those for a wide variety of other species, and yet we still have a lot of trouble figuring out what genes do. Mapping genes to their function is called the "genotype-to-phenotype problem," where phenotype is whatever is changed in the organism when a gene's function is altered.
MeSH Categories: Animals, Epistasis, Genetic, Gene Regulatory Networks, Genetic Techniques, Genomics, *Genotype, Humans, Metabolic Networks and Pathways, Models, Genetic, *Phenotype, Plants/*genetics, Polymorphism, Genetic, Quantitative Trait Loci, *Systems Biology, *Variation (Genetics)
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- Extending genomics to natural communities and ecosystems.Publication Date: 2008 Apr 25 PMID: 18436780
Authors: Whitham, T. G. - Difazio, S. P. - Schweitzer, J. A. - Shuster, S. M. - Allan, G. J. - Bailey, J. K. - Woolbright, S. A.
Journal: Science
An important step in the integration of ecology and genomics is the progression from molecular studies of relatively simple model systems to complex field systems. The recent availability of sequenced genomes from key plants is leading to a new understanding of the molecular drivers of community composition and ecosystem processes. As genome sequences accumulate for species that form intimate associations in nature, a detailed view may emerge as to how these associations cause changes among species at the nucleotide level. This advance could dramatically alter views about the structure and evolution of communities and ecosystems.
MeSH Categories: Animals, *Ecosystem, Epigenesis, Genetic, Evolution, *Genome, Plant, *Genomics, *Plant Physiology, Plants/*genetics, Selection (Genetics), Symbiosis
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- The epigenetic landscape of plants.Publication Date: 2008 Apr 25 PMID: 18436779
Authors: Zhang, X.
Journal: Science
In plants, DNA methylation, histone modifications, and RNA interference play critically important roles in regulating chromatin structure, thereby profoundly affecting transcription and other molecular events. Recent advances in microarray and high-throughput sequencing technologies have enabled genome-wide studies of these pathways in great detail. The vast amounts of "epigenomic" data generated so far have provided new insights into the mechanisms and functions of these pathways and have broadened our understanding of the structure and organization of plant chromatin as a whole.
MeSH Categories: Arabidopsis/*genetics/physiology, DNA Methylation, *Epigenesis, Genetic, Gene Expression Profiling, Gene Expression Regulation, Plant, *Genome, Plant, Histones/metabolism, Methylation, Plant Physiology, Plants/*genetics, RNA Interference, RNA, Small Interfering
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- Synteny and collinearity in plant genomes.Publication Date: 2008 Apr 25 PMID: 18436778
Authors: Tang, H. - Bowers, J. E. - Wang, X. - Ming, R. - Alam, M. - Paterson, A. H.
Journal: Science
Correlated gene arrangements among taxa provide a valuable framework for inference of shared ancestry of genes and for the utilization of findings from model organisms to study less-well-understood systems. In angiosperms, comparisons of gene arrangements are complicated by recurring polyploidy and extensive genome rearrangement. New genome sequences and improved analytical approaches are clarifying angiosperm evolution and revealing patterns of differential gene loss after genome duplication and differential gene retention associated with evolution of some morphological complexity. Because of variability in DNA substitution rates among taxa and genes, deviation from collinearity might be a more reliable phylogenetic character.
MeSH Categories: Angiosperms/classification/*genetics, Chromosomes, Plant/genetics, Evolution, Gene Duplication, Gene Order, Gene Rearrangement, *Genome, Plant, Genomics, Karyotyping, Phylogeny, Polyploidy, Sequence Analysis, DNA, *Synteny
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- Selection on major components of angiosperm genomes.Publication Date: 2008 Apr 25 PMID: 18436777
Authors: Gaut, B. S. - Ross-Ibarra, J.
Journal: Science
Angiosperms are a relatively recent evolutionary innovation, but their genome sizes have diversified remarkably since their origin, at a rate beyond that of most other taxa. Genome size is often correlated with plant growth and ecology, and extremely large genomes may be limited both ecologically and evolutionarily. Yet the relationship between genome size and natural selection remains poorly understood. The manifold cellular and physiological effects of large genomes may be a function of selection on the major components that contribute to genome size, such as transposable elements and gene duplication. To understand the nature of selection on these genomic components, both population-genetic and comparative approaches are needed.
MeSH Categories: Angiosperms/*genetics/physiology, DNA Transposable Elements, Gene Duplication, Genetics, Population, *Genome, Plant, Genomics, Phenotype, *Selection (Genetics), Variation (Genetics)
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- Genomic plasticity and the diversity of polyploid plants.Publication Date: 2008 Apr 25 PMID: 18436776
Authors: Leitch, A. R. - Leitch, I. J.
Journal: Science
Polyploidy, a change whereby the entire chromosome set is multiplied, arises through mitotic or meiotic misdivisions and frequently involves unreduced gametes and interspecific hybridization. The success of newly formed angiosperm polyploids is partly attributable to their highly plastic genome structure, as manifested by tolerance to changing chromosome numbers (aneuploidy and polyploidy), genome size, (retro)transposable element mobility, insertions, deletions, and epigenome restructuring. The ability to withstand large-scale changes, frequently within one or a few generations, is associated with a restructuring of the transcriptome, metabolome, and proteome and can result in an altered phenotype and ecology. Thus, polyploid-induced changes can generate individuals that are able to exploit new niches or to outcompete progenitor species. This process has been a major driving force behind the divergence of the angiosperms and their biodiversity.
MeSH Categories: Angiosperms/classification/*genetics/metabolism, Biodiversity, Chromosomes, Plant/genetics, Evolution, Genetic Speciation, *Genome, Plant, Hybridization, Genetic, Nondisjunction, Genetic, Plant Proteins/genetics/metabolism, *Polyploidy, Proteome, Transcription, Genetic, *Variation (Genetics)
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- Genome-enabled approaches shed new light on plant metabolism.Publication Date: 2008 Apr 25 PMID: 18436775
Authors: DellaPenna, D. - Last, R. L.
Journal: Science
Plant metabolism research has experienced a second golden age resulting from synergies between genome-enabled technologies and classical biochemistry. The rapid rate at which genomics data are being accumulated creates increased needs for robust metabolomic technologies and fast and accurate methods for identifying the activities of enzymes.
MeSH Categories: Cell Wall/metabolism, Gene Expression Profiling, *Genes, Plant, Genome, Plant, *Genomics, Metabolic Networks and Pathways, Plants/enzymology/*genetics/*metabolism, Sequence Analysis, DNA
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- Sowing the seeds for high-energy plants.Publication Date: 2008 Apr 25 PMID: 18436774
Authors: Kintisch, E.
Journal: Science
MeSH Categories: *Agriculture, Cell Wall/metabolism, Cellulose/metabolism, *Energy-Generating Resources, *Genome, Plant, *Genomics, Plants/*genetics/growth & development/*metabolism
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- A life with grapes.Publication Date: 2008 Apr 25 PMID: 18436773
Authors: Travis, J.
Journal: Science
MeSH Categories: *Genome, Plant, History, 20th Century, History, 21st Century, Portraits as Topic, United States, Vitis/*genetics, *Wine
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- Uncorking the grape genome.Publication Date: 2008 Apr 25 PMID: 18436772
Authors: Travis, J.
Journal: Science
MeSH Categories: Crosses, Genetic, France, Genes, Plant, *Genome, Plant, International Cooperation, Italy, Microsatellite Repeats, Plant Diseases, Plants, Genetically Modified, Sequence Analysis, DNA, Vitis/*genetics, *Wine
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- Is the drought over for pharming?Publication Date: 2008 Apr 25 PMID: 18436771
Authors: Kaiser, J.
Journal: Science
MeSH Categories: *Biotechnology, Clinical Trials as Topic, Drug Approval, *Drug Industry, Humans, *Pharmaceutical Preparations, *Plants, Genetically Modified/metabolism, Public Opinion, Recombinant Proteins/biosynthesis, United States, United States Food and Drug Administration
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- Papaya takes on ringspot virus and wins.Publication Date: 2008 Apr 25 PMID: 18436770
Authors: Stokstad, E.
Journal: Science
MeSH Categories: Carica/*genetics/*virology, Crops, Agricultural/economics/*genetics, Developing Countries, Hawaii, Plant Diseases/*virology, *Plants, Genetically Modified, Potyvirus/*pathogenicity
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- Tough lessons from golden rice.Publication Date: 2008 Apr 25 PMID: 18436769
Authors: Enserink, M.
Journal: Science
MeSH Categories: Child, Crops, Agricultural/*genetics, Government Regulation, Humans, Industry, Oryza sativa/*genetics/metabolism, *Plants, Genetically Modified, Seeds/genetics/metabolism, Vitamin A Deficiency/*prevention & control, beta Carotene/*biosynthesis
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- GM crops: a world view.Publication Date: 2008 Apr 25 PMID: 18436768
Authors:
Journal: Science
MeSH Categories: Agriculture/*statistics & numerical data, Crops, Agricultural/*genetics, *Internationality, *Plants, Genetically Modified
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- Multimedia feature: plant genomes.Publication Date: 2008 Apr 25 PMID: 18436767
Authors:
Journal: Science
MeSH Categories: Crops, Agricultural/genetics, *Genome, Plant, Plants, Genetically Modified
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- Green genes. Plant genomes. Introduction.Publication Date: 2008 Apr 25 PMID: 18436766
Authors: Zahn, L. M. - Hines, P. J. - Pennisi, E. - Travis, J.
Journal: Science
MeSH Categories: Crops, Agricultural/genetics, *Genome, Plant, *Genomics, Plants/*genetics/metabolism, *Plants, Genetically Modified
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- Cell biology. RNA metabolism and oncogenesis.Publication Date: 2008 Apr 25 PMID: 18436765
Authors: Johnson, D. L. - Johnson, S. A.
Journal: Science
MeSH Categories: Animals, Cell Proliferation, *Cell Transformation, Neoplastic, Mice, Nuclear Proteins/metabolism, *Protein Biosynthesis, RNA/genetics/*metabolism, RNA Polymerase III/*metabolism, RNA, Messenger/genetics/metabolism, RNA, Ribosomal/metabolism, RNA, Transfer/*metabolism, RNA, Transfer, Met/metabolism, RNA-Binding Proteins/metabolism, Signal Transduction, Transcription Factors, General/metabolism, Transcription Factors, TFIII/metabolism, *Transcription, Genetic
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- Climate change. Carbon crucible.Publication Date: 2008 Apr 25 PMID: 18436764
Authors: Marquis, M. - Tans, P.
Journal: Science
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- Cell biology. A one-sided signal.Publication Date: 2008 Apr 25 PMID: 18436763
Authors: Fairn, G. D. - Grinstein, S.
Journal: Science
MeSH Categories: Adenosine Triphosphatases/metabolism, Animals, Apoptosis, Caenorhabditis elegans/genetics/metabolism, Caenorhabditis elegans Proteins/*metabolism, Cell Membrane/*metabolism, Endoplasmic Reticulum/metabolism, Golgi Apparatus/metabolism, Lipid Bilayers, Phosphatidylserines/*metabolism, Phospholipid Transfer Proteins/*metabolism, *Pinocytosis, RNA Interference, *Signal Transduction, Vaccinia virus/*physiology, *Virus Internalization
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- Planetary science. Identifying ancient asteroids.Publication Date: 2008 Apr 25 PMID: 18436762
Authors: Burbine, T. H.
Journal: Science
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- Biophysics. Enigmas of blood clot elasticity.Publication Date: 2008 Apr 25 PMID: 18436761
Authors: Weisel, J. W.
Journal: Science
MeSH Categories: Biophysics, Blood Coagulation/*physiology, Computer Simulation, Elasticity, Fibr |
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