Science

Science Podcast.

Publication Date: 2008 Aug 1 PMID: 18669864
Authors:
Journal: Science

Science Podcast The 1 August 2008 show includes a water-splitting catalyst for energy storage applications, the molecular basis of pain, Chinas environmental challenges, and more.

post to: CiteULike

The cell and molecular basis of mechanical, cold, and inflammatory pain.

Publication Date: 2008 Aug 1 PMID: 18669863
Authors: Abrahamsen, B. - Zhao, J. - Asante, C. O. - Cendan, C. M. - Marsh, S. - Martinez-Barbera, J. P. - Nassar, M. A. - Dickenson, A. H. - Wood, J. N.
Journal: Science

Peripheral pain pathways are activated by a range of stimuli. We used diphtheria toxin to kill all mouse postmitotic sensory neurons expressing the sodium channel Nav1.8. Mice showed normal motor activity and low-threshold mechanical and acute noxious heat responses but did not respond to noxious mechanical pressure or cold. They also showed a loss of enhanced pain responses and spontaneous pain behavior upon treatment with inflammatory insults. In contrast, nerve injury led to heightened pain sensitivity to thermal and mechanical stimuli indistinguishable from that seen with normal littermates. Pain behavior correlates well with central input from sensory neurons measured electrophysiologically in vivo. These data demonstrate that Na(v)1.8-expressing neurons are essential for mechanical, cold, and inflammatory pain but not for neuropathic pain or heat sensing.

post to: CiteULike

Pyogenic bacterial infections in humans with MyD88 deficiency.

Publication Date: 2008 Aug 1 PMID: 18669862
Authors: von Bernuth, H. - Picard, C. - Jin, Z. - Pankla, R. - Xiao, H. - Ku, C. L. - Chrabieh, M. - Mustapha, I. B. - Ghandil, P. - Camcioglu, Y. - Vasconcelos, J. - Sirvent, N. - Guedes, M. - Vitor, A. B. - Herrero-Mata, M. J. - Arostegui, J. I. - Rodrigo, C. - Alsina, L. - Ruiz-Ortiz, E. - Juan, M. - Fortuny, C. - Yague, J. - Anton, J. - Pascal, M. - Chang, H. H. - Janniere, L. - Rose, Y. - Garty, B. Z. - Chapel, H. - Issekutz, A. - Marodi, L. - Rodriguez-Gallego, C. - Banchereau, J. - Abel, L. - Li, X. - Chaussabel, D. - Puel, A. - Casanova, J. L.
Journal: Science

MyD88 is a key downstream adapter for most Toll-like receptors (TLRs) and interleukin-1 receptors (IL-1Rs). MyD88 deficiency in mice leads to susceptibility to a broad range of pathogens in experimental settings of infection. We describe a distinct situation in a natural setting of human infection. Nine children with autosomal recessive MyD88 deficiency suffered from life-threatening, often recurrent pyogenic bacterial infections, including invasive pneumococcal disease. However, these patients were otherwise healthy, with normal resistance to other microbes. Their clinical status improved with age, but not due to any cellular leakiness in MyD88 deficiency. The MyD88-dependent TLRs and IL-1Rs are therefore essential for protective immunity to a small number of pyogenic bacteria, but redundant for host defense to most natural infections.

post to: CiteULike

Regulation of CD45 alternative splicing by heterogeneous ribonucleoprotein, hnRNPLL.

Publication Date: 2008 Aug 1 PMID: 18669861
Authors: Oberdoerffer, S. - Moita, L. F. - Neems, D. - Freitas, R. P. - Hacohen, N. - Rao, A.
Journal: Science

The transition from naive to activated T cells is marked by alternative splicing of pre-mRNA encoding the transmembrane phosphatase CD45. Using a short hairpin RNA interference screen, we identified heterogeneous ribonucleoprotein L-like (hnRNPLL) as a critical inducible regulator of CD45 alternative splicing. HnRNPLL was up-regulated in stimulated T cells, bound CD45 transcripts, and was both necessary and sufficient for CD45 alternative splicing. Depletion or overexpression of hnRNPLL in B and T cell lines and primary T cells resulted in reciprocal alteration of CD45RA and RO expression. Exon array analysis suggested that hnRNPLL acts as a global regulator of alternative splicing in activated T cells. Induction of hnRNPLL during hematopoietic cell activation and differentiation may allow cells to rapidly shift their transcriptomes to favor proliferation and inhibit cell death.

post to: CiteULike

The global stoichiometry of litter nitrogen mineralization.

Publication Date: 2008 Aug 1 PMID: 18669860
Authors: Manzoni, S. - Jackson, R. B. - Trofymow, J. A. - Porporato, A.
Journal: Science

Plant residue decomposition and the nutrient release to the soil play a major role in global carbon and nutrient cycling. Although decomposition rates vary strongly with climate, nitrogen immobilization into litter and its release in mineral forms are mainly controlled by the initial chemical composition of the residues. We used a data set of approximately 2800 observations to show that these global nitrogen-release patterns can be explained by fundamental stoichiometric relationships of decomposer activity. We show how litter quality controls the transition from nitrogen accumulation into the litter to release and alters decomposers' respiration patterns. Our results suggest that decomposers lower their carbon-use efficiency to exploit residues with low initial nitrogen concentration, a strategy used broadly by bacteria and consumers across trophic levels.

post to: CiteULike

Colossal ionic conductivity at interfaces of epitaxial ZrO2:Y2O3/SrTiO3 heterostructures.

Publication Date: 2008 Aug 1 PMID: 18669859
Authors: Garcia-Barriocanal, J. - Rivera-Calzada, A. - Varela, M. - Sefrioui, Z. - Iborra, E. - Leon, C. - Pennycook, S. J. - Santamaria, J.
Journal: Science

The search for electrolyte materials with high oxygen conductivities is a key step toward reducing the operation temperature of fuel cells, which is currently above 700 degrees C. We report a high lateral ionic conductivity, showing up to eight orders of magnitude enhancement near room temperature, in yttria-stabilized zirconia (YSZ)/strontium titanate epitaxial heterostructures. The enhancement of the conductivity is observed, along with a YSZ layer thickness-independent conductance, showing that it is an interface process. We propose that the atomic reconstruction at the interface between highly dissimilar structures (such as fluorite and perovskite) provides both a large number of carriers and a high-mobility plane, yielding colossal values of the ionic conductivity.

post to: CiteULike

Structures of neutral Au7, Au19, and Au20 clusters in the gas phase.

Publication Date: 2008 Aug 1 PMID: 18669858
Authors: Gruene, P. - Rayner, D. M. - Redlich, B. - van der Meer, A. F. - Lyon, J. T. - Meijer, G. - Fielicke, A.
Journal: Science

The catalytic properties of gold nanoparticles are determined by their electronic and geometric structures. We revealed the geometries of several small neutral gold clusters in the gas phase by using vibrational spectroscopy between 47 and 220 wavenumbers. A two-dimensional structure for neutral Au7 and a pyramidal structure for neutral Au20 can be unambiguously assigned. The reduction of the symmetry when a corner atom is cut from the tetrahedral Au20 cluster is directly reflected in the vibrational spectrum of Au19.

post to: CiteULike

High rates of oxygen reduction over a vapor phase-polymerized PEDOT electrode.

Publication Date: 2008 Aug 1 PMID: 18669857
Authors: Winther-Jensen, B. - Winther-Jensen, O. - Forsyth, M. - Macfarlane, D. R.
Journal: Science

The air electrode, which reduces oxygen (O2), is a critical component in energy generation and storage applications such as fuel cells and metal/air batteries. The highest current densities are achieved with platinum (Pt), but in addition to its cost and scarcity, Pt particles in composite electrodes tend to be inactivated by contact with carbon monoxide (CO) or by agglomeration. We describe an air electrode based on a porous material coated with poly(3,4-ethylenedioxythiophene) (PEDOT), which acts as an O2 reduction catalyst. Continuous operation for 1500 hours was demonstrated without material degradation or deterioration in performance. O2 conversion rates were comparable with those of Pt-catalyzed electrodes of the same geometry, and the electrode was not sensitive to CO. Operation was demonstrated as an air electrode and as a dissolved O2 electrode in aqueous solution.

post to: CiteULike

Protostar formation in the early universe.

Publication Date: 2008 Aug 1 PMID: 18669856
Authors: Yoshida, N. - Omukai, K. - Hernquist, L.
Journal: Science

The nature of the first generation of stars in the universe remains largely unknown. Observations imply the existence of massive primordial stars early in the history of the universe, and the standard theory for the growth of cosmic structure predicts that structures grow hierarchically through gravitational instability. We have developed an ab initio computer simulation of the formation of primordial stars that follows the relevant atomic and molecular processes in a primordial gas in an expanding universe. The results show that primeval density fluctuations left over from the Big Bang can drive the formation of a tiny protostar with a mass 1% that of the Sun. The protostar is a seed for the subsequent formation of a massive primordial star.

post to: CiteULike

Evidence of global chlorophyll d.

Publication Date: 2008 Aug 1 PMID: 18669855
Authors: Kashiyama, Y. - Miyashita, H. - Ohkubo, S. - Ogawa, N. O. - Chikaraishi, Y. - Takano, Y. - Suga, H. - Toyofuku, T. - Nomaki, H. - Kitazato, H. - Nagata, T. - Ohkouchi, N.
Journal: Science

Although analyses of chlorophyll d (Chl d)-dominated oxygenic photosystems have been conducted since their discovery 12 years ago, Chl d distribution in the environment and quantitative importance for aquatic photosynthesis remain to be investigated. We analyzed the pigment compositions of surface sediments and detected Chl d and its derivatives from diverse aquatic environments. Our data show that the viable habitat for Chl d-producing phototrophs extends across salinities of 0 to 50 practical salinity units and temperatures of 1 degrees to 40 degrees C, suggesting that Chl d production can be ubiquitously observed in aquatic environments that receive near-infrared light. The relative abundances of Chl d derivatives over that of Chl a derivatives in the studied samples are up to 4%, further suggesting that Chl d-based photosynthesis plays a quantitatively important role in the aquatic photosynthesis.

post to: CiteULike

Hopping hotspots: global shifts in marine biodiversity.

Publication Date: 2008 Aug 1 PMID: 18669854
Authors: Renema, W. - Bellwood, D. R. - Braga, J. C. - Bromfield, K. - Hall, R. - Johnson, K. G. - Lunt, P. - Meyer, C. P. - McMonagle, L. B. - Morley, R. J. - O'Dea, A. - Todd, J. A. - Wesselingh, F. P. - Wilson, M. E. - Pandolfi, J. M.
Journal: Science

Hotspots of high species diversity are a prominent feature of modern global biodiversity patterns. Fossil and molecular evidence is starting to reveal the history of these hotspots. There have been at least three marine biodiversity hotspots during the past 50 million years. They have moved across almost half the globe, with their timing and locations coinciding with major tectonic events. The birth and death of successive hotspots highlights the link between environmental change and biodiversity patterns. The antiquity of the taxa in the modern Indo-Australian Archipelago hotspot emphasizes the role of pre-Pleistocene events in shaping modern diversity patterns.

post to: CiteULike

Climate change. Ecosystem disturbance, carbon, and climate.

Publication Date: 2008 Aug 1 PMID: 18669853
Authors: Running, S. W.
Journal: Science

post to: CiteULike

Materials science. Electrochemical capacitors for energy management.

Publication Date: 2008 Aug 1 PMID: 18669852
Authors: Miller, J. R. - Simon, P.
Journal: Science

post to: CiteULike

Climate change. Did you say "fast"?

Publication Date: 2008 Aug 1 PMID: 18669851
Authors: Fluckiger, J.
Journal: Science

post to: CiteULike

Cell signaling. "Make and brake" in signaling.

Publication Date: 2008 Aug 1 PMID: 18669850
Authors: Eliopoulos, A. G.
Journal: Science

post to: CiteULike

Astronomy. The cosmic Rosetta stone.

Publication Date: 2008 Aug 1 PMID: 18669849
Authors: Bromm, V.
Journal: Science

post to: CiteULike

Immunology. A splicing switch for T cells.

Publication Date: 2008 Aug 1 PMID: 18669848
Authors: Holmes, N.
Journal: Science

post to: CiteULike

Research funding. Structural disequilibria in biomedical research.

Publication Date: 2008 Aug 1 PMID: 18669847
Authors: Teitelbaum, M. S.
Journal: Science

post to: CiteULike

Comment on "Magnetic resonance spectroscopy identifies neural progenitor cells in the live human brain".

Publication Date: 2008 Aug 1 PMID: 18669846
Authors: Jansen, J. F. - Gearhart, J. D. - Bulte, J. W.
Journal: Science

Manganas et al. (Reports, 9 November 2007, p. 980) reported the discovery of a biomarker specific for neural progenitor cells detectable using magnetic resonance spectroscopy. A new algorithm was developed to extract the biomarker from noisy in vivo data. We question how this algorithm was validated, because the biomarker overlaps with peaks from nonspecific lipid signals.

post to: CiteULike

Comment on "Magnetic resonance spectroscopy identifies neural progenitor cells in the live human brain".

Publication Date: 2008 Aug 1 PMID: 18669845
Authors: Friedman, S. D.
Journal: Science

Manganas et al. (Reports, 9 November 2007, p. 980) used a metabolic biomarker identified in vitro to characterize the existence of neural progenitor cells in vivo. Although their detailed experiments and general approach are laudable, aspects of their magnetic resonance spectroscopy data and analyses raise questions about their results.

post to: CiteULike

Comment on "magnetic resonance spectroscopy identifies neural progenitor cells in the live human brain".

Publication Date: 2008 Aug 1 PMID: 18669844
Authors: Hoch, J. C. - Maciejewski, M. W. - Gryk, M. R.
Journal: Science

Manganas et al. (Reports, 9 November 2007, p. 980) used nuclear magnetic resonance spectroscopy to identify a biomarker of neural progenitor cells. However, their analysis relies on spectral processing methods that are known to be problematic. Absent detection using alternate methods of spectrum analysis or controls to quantify the false discovery rate, their conclusions may be premature.

post to: CiteULike

Gene mutations and cognitive delay.

Publication Date: 2008 Aug 1 PMID: 18669843
Authors: Leonard, C. M. - Kuldau, J. M.
Journal: Science

post to: CiteULike

Survey says: name a role model.

Publication Date: 2008 Aug 1 PMID: 18669842
Authors: Webb, M. R.
Journal: Science

post to: CiteULike

Policy forum offered new ideas.

Publication Date: 2008 Aug 1 PMID: 18669841
Authors: Liu, J. - Diamond, J.
Journal: Science

post to: CiteULike

The cost benefits of early detection.

Publication Date: 2008 Aug 1 PMID: 18669840
Authors: Guntheroth, W. G.
Journal: Science

post to: CiteULike

China's environmental challenges. Beijing's marathon run to clean foul air nears finish line.

Publication Date: 2008 Aug 1 PMID: 18669839
Authors: Stone, R.
Journal: Science

post to: CiteULike

China's environmental challenges. A green fervor sweeps the Qinghai-Tibetan Plateau.

Publication Date: 2008 Aug 1 PMID: 18669838
Authors: Xin, H.
Journal: Science

post to: CiteULike

China's environmental challenges. Fears over western water crisis.

Publication Date: 2008 Aug 1 PMID: 18669837
Authors: Stone, R.
Journal: Science

post to: CiteULike

China's environmental challenges. Three Gorges Dam: into the unknown.

Publication Date: 2008 Aug 1 PMID: 18669836
Authors: Stone, R.
Journal: Science

post to: CiteULike

Science at the Olympics. Gender balance.

Publication Date: 2008 Aug 1 PMID: 18669835
Authors:
Journal: Science

post to: CiteULike

Science at the Olympics. Does doping work?

Publication Date: 2008 Aug 1 PMID: 18669834
Authors: Enserink, M.
Journal: Science

post to: CiteULike

Science at the Olympics. Can neuroscience provide a mental edge?

Publication Date: 2008 Aug 1 PMID: 18669833
Authors: Miller, G.
Journal: Science

post to: CiteULike

Science at the Olympics. Do new materials make the athlete?

Publication Date: 2008 Aug 1 PMID: 18669832
Authors: Lu, A.
Journal: Science

post to: CiteULike

Science at the Olympics. What's age got to do with it?

Publication Date: 2008 Aug 1 PMID: 18669831
Authors:
Journal: Science

post to: CiteULike

Science at the Olympics. Can ice vests provide a competitive chill?

Publication Date: 2008 Aug 1 PMID: 18669830
Authors: Cho, A.
Journal: Science

post to: CiteULike

Science at the Olympics. Will Beijing's dirty air hurt performance?

Publication Date: 2008 Aug 1 PMID: 18669829
Authors: Stokstad, E.
Journal: Science

post to: CiteULike

Paleontology. Is dinosaur 'soft tissue' really slime?

Publication Date: 2008 Aug 1 PMID: 18669828
Authors: Zimmer, C.
Journal: Science

post to: CiteULike

Lino Baranao interview. New minister raises expectations for science in Argentina. Interview by Jocelyn Kaiser and Eliot Marshall.

Publication Date: 2008 Aug 1 PMID: 18669827
Authors: Baranao, L.
Journal: Science

post to: CiteULike

Risk assessment. Regulators seek to redefine 'working life'.

Publication Date: 2008 Aug 1 PMID: 18669826
Authors: Malakoff, D.
Journal: Science

post to: CiteULike

Chemistry. New catalyst marks major step in the march toward hydrogen fuel.

Publication Date: 2008 Aug 1 PMID: 18669825
Authors: Service, R. F.
Journal: Science

post to: CiteULike

Blue skies for China.

Publication Date: 2008 Aug 1 PMID: 18669824
Authors: Fu, B.
Journal: Science

post to: CiteULike

Regional Synthesis of Mediterranean Atmospheric Circulation During the Last Glacial Maximum.

Publication Date: 2008 Jul 31 PMID: 18669823
Authors: Kuhlemann, J. - Rohling, E. J. - Krumrei, I. - Kubik, P. - Ivy-Ochs, S. - Kucera, M.
Journal: Science

Atmospheric circulation leaves few direct traces in the geological record, making reconstructions of this crucial element of the climate system inherently difficult. Here, we produce a regional Mediterranean synthesis of palaeo-proxy data from sea-surface to alpine altitudes. This provides - for the first time - a detailed observational context of change in the three-dimensional structure of atmospheric circulation between the Last Glacial Maximum (LGM) (~23-19 ka) and Present. The synthesis reveals evidence for frequent cold polar air incursions, topographically channelled into the northwestern Mediterranean. Anomalously steep vertical temperature gradients in the central Mediterranean imply local convective precipitation. We find the LGM patterns to be analogous, though amplified, to previously reconstructed phases of enhanced meridional winter circulation during the Maunder Minimum (Little Ice Age).

post to: CiteULike

Dual Origin of Tissue-Specific Progenitor Cells in Drosophila Tracheal Remodeling.

Publication Date: 2008 Jul 31 PMID: 18669822
Authors: Weaver, M. - Krasnow, M. A.
Journal: Science

During Drosophila metamorphosis, most larval cells die. Pupal and adult tissues form from imaginal cells, tissue-specific progenitors allocated in embryogenesis that remain quiescent during embryonic and larval life. Clonal analysis and fate mapping of single, identified cells show that tracheal system remodeling at metamorphosis involves a classical imaginal cell population, and a population of differentiated, functional larval tracheal cells that reenter the cell cycle and regain developmental potency. In late larvae, both populations are activated and proliferate, spread over and replace old branches, and diversify into various stalk and coiled tracheolar cells under FGF control. Thus, Drosophila pupal/adult tissue progenitors can arise both by early allocation of multipotent cells and late return of differentiated cells to a multipotent state, even within a single tissue.

post to: CiteULike

Induced Pluripotent Stem Cells Generated from Patients with ALS Can Be Differentiated into Motor Neurons.

Publication Date: 2008 Jul 31 PMID: 18669821
Authors: Dimos, J. T. - Rodolfa, K. T. - Niakan, K. K. - Weisenthal, L. M. - Mitsumoto, H. - Chung, W. - Croft, G. F. - Saphier, G. - Leibel, R. - Goland, R. - Wichterle, H. - Henderson, C. E. - Eggan, K.
Journal: Science

The generation of pluripotent stem cells from an individual patient would enable the large-scale production of the cell-types affected by that patient's disease. These cells could in turn be used for disease modeling, drug discovery, and eventually autologous cell-replacement therapies. Although recent studies have demonstrated the reprogramming of human fibroblasts to a pluripotent state, it remains unclear whether these induced pluripotent stem (iPS) cells can be produced directly from elderly patients with chronic disease. We have generated iPS cells from an 82-year-old woman diagnosed with a familial form of amyotrophic lateral sclerosis (ALS). These patient-specific iPS cells possess properties of embryonic stem cells and were successfully directed to differentiate into motor neurons, the cell type destroyed in ALS.

post to: CiteULike

In Situ Formation of an Oxygen-Evolving Catalyst in Neutral Water Containing Phosphate and Co2+

Publication Date: 2008 Jul 31 PMID: 18669820
Authors: Kanan, M. W. - Nocera, D. G.
Journal: Science

The utilization of solar energy on a large scale requires its storage. In natural photosynthesis, energy from sunlight is used to rearrange the bonds of water to O2 and H2-equivalents. The realization of artificial systems that perform similar "water splitting" requires catalysts that produce O2 from water without the need for excessive driving potentials. Here, we report such a catalyst that forms upon the oxidative polarization of an inert indium tin oxide electrode in phosphate-buffered water containing Co(2+). A variety of analytical techniques indicates the presence of phosphate in an approximate 1:2 ratio with cobalt in this material. The pH dependence of the catalytic activity also implicates HPO4(2-) as the proton acceptor in the O2-producing reaction. This catalyst not only forms in situ from earth-abundant materials but also operates in neutral water under ambient conditions.

post to: CiteULike

Manipulating the metazoan mitochondrial genome with targeted restriction enzymes.

Publication Date: 2008 Jul 25 PMID: 18653897
Authors: Xu, H. - DeLuca, S. Z. - O'Farrell, P. H.
Journal: Science

High copy number and random segregation confound genetic analysis of the mitochondrial genome. We developed an efficient selection for heritable mitochondrial genome (mtDNA) mutations in Drosophila, thereby enhancing a metazoan model for study of mitochondrial genetics and mutations causing human mitochondrial disease. Targeting a restriction enzyme to mitochondria in the germline compromised fertility, but escaper progeny carried homoplasmic mtDNA mutations lacking the cleavage site. Among mutations eliminating a site in the cytochrome c oxidase gene, mt:CoI(A302T) was healthy, mt:CoI(R301L) was male sterile but otherwise healthy, and mt:CoI(R301S) exhibited a wide range of defects, including growth retardation, neurodegeneration, muscular atrophy, male sterility, and reduced life span. Thus, germline expression of mitochondrial restriction enzymes creates a powerful selection and has allowed direct isolation of mitochondrial mutants in a metazoan.

MeSH Categories: Animals, Animals, Genetically Modified, Bacterial Proteins/genetics/metabolism, DNA Restriction Enzymes/genetics/*metabolism, DNA, Mitochondrial/*genetics/metabolism, Deoxyribonucleases, Type II Site-Specific/genetics/*metabolism, Drosophila melanogaster/embryology/*genetics/growth &, development/metabolism, Embryo, Nonmammalian/metabolism, Eye/anatomy & histology/growth & development, Female, Genome, Insect, *Genome, Mitochondrial, Infertility, Male, Male, Mitochondrial Diseases/genetics/metabolism, Morphogenesis, Muscles/ultrastructure, Muscular Dystrophy, Animal, *Mutation, Spermatogenesis

post to: CiteULike

The crystal structure of [Fe]-hydrogenase reveals the geometry of the active site.

Publication Date: 2008 Jul 25 PMID: 18653896
Authors: Shima, S. - Pilak, O. - Vogt, S. - Schick, M. - Stagni, M. S. - Meyer-Klaucke, W. - Warkentin, E. - Thauer, R. K. - Ermler, U.
Journal: Science

Biological formation and consumption of molecular hydrogen (H2) are catalyzed by hydrogenases, of which three phylogenetically unrelated types are known: [NiFe]-hydrogenases, [FeFe]-hydrogenases, and [Fe]-hydrogenase. We present a crystal structure of [Fe]-hydrogenase at 1.75 angstrom resolution, showing a mononuclear iron coordinated by the sulfur of cysteine 176, two carbon monoxide (CO) molecules, and the sp2-hybridized nitrogen of a 2-pyridinol compound with back-bonding properties similar to those of cyanide. The three-dimensional arrangement of the ligands is similar to that of thiolate, CO, and cyanide ligated to the low-spin iron in binuclear [NiFe]- and [FeFe]-hydrogenases, although the enzymes have evolved independently and the CO and cyanide ligands are not found in any other metalloenzyme. The related iron ligation pattern of hydrogenases exemplifies convergent evolution and presumably plays an essential role in H2 activation. This finding may stimulate the ongoing synthesis of catalysts that could substitute for platinum in applications such as fuel cells.

MeSH Categories: Apoenzymes/chemistry, Binding Sites, Carbon Monoxide/chemistry, Catalytic Domain, Coenzymes/chemistry, Crystallography, X-Ray, Cyanides/chemistry/metabolism, Dimerization, Evolution, Molecular, Holoenzymes/chemistry, Hydrogen/chemistry/*metabolism, Hydrogenase/*chemistry/isolation & purification/metabolism, Iron/chemistry, Ligands, Methane/biosynthesis, Methanococcales/*enzymology, Models, Molecular, Oxidation-Reduction, Protein Structure, Secondary, Protein Structure, Tertiary

post to: CiteULike

ERdj5 is required as a disulfide reductase for degradation of misfolded proteins in the ER.

Publication Date: 2008 Jul 25 PMID: 18653895
Authors: Ushioda, R. - Hoseki, J. - Araki, K. - Jansen, G. - Thomas, D. Y. - Nagata, K.
Journal: Science

Membrane and secretory proteins cotranslationally enter and are folded in the endoplasmic reticulum (ER). Misfolded or unassembled proteins are discarded by a process known as ER-associated degradation (ERAD), which involves their retrotranslocation into the cytosol. ERAD substrates frequently contain disulfide bonds that must be cleaved before their retrotranslocation. Here, we found that an ER-resident protein ERdj5 had a reductase activity, cleaved the disulfide bonds of misfolded proteins, and accelerated ERAD through its physical and functional associations with EDEM (ER degradation-enhancing alpha-mannosidase-like protein) and an ER-resident chaperone BiP. Thus, ERdj5 is a member of a supramolecular ERAD complex that recognizes and unfolds misfolded proteins for their efficient retrotranslocation.

MeSH Categories: Amino Acid Motifs, Amino Acid Substitution, Animals, Cell Line, Endoplasmic Reticulum/*metabolism, Glutathione/metabolism, HSP40 Heat-Shock Proteins/chemistry/genetics/*metabolism, Heat-Shock Proteins/metabolism, Humans, Immunoglobulin J-Chains/chemistry/metabolism, Membrane Proteins/metabolism, Mice, Molecular Chaperones/chemistry/genetics/*metabolism, Mutation, Oxidation-Reduction, Protein Disulfide Reductase (Glutathione)/metabolism, Protein Disulfide-Isomerase/metabolism, Protein Folding, Protein Structure, Tertiary, Proteins/chemistry/*metabolism, Recombinant Proteins/chemistry/metabolism, Transfection, Two-Hybrid System Techniques, alpha 1-Antitrypsin/chemistry/metabolism

post to: CiteULike

A molecular determinant for the establishment of sister chromatid cohesion.

Publication Date: 2008 Jul 25 PMID: 18653894
Authors: Unal, E. - Heidinger-Pauli, J. M. - Kim, W. - Guacci, V. - Onn, I. - Gygi, S. P. - Koshland, D. E.
Journal: Science

Chromosome segregation, transcriptional regulation, and repair of DNA double-strand breaks require the cohesin protein complex. Cohesin holds the replicated chromosomes (sister chromatids) together to mediate sister chromatid cohesion. The mechanism of how cohesion is established is unknown. We found that in budding yeast, the head domain of the Smc3p subunit of cohesin is acetylated by the Eco1p acetyltransferase at two evolutionarily conserved residues, promoting the chromatin-bound cohesin to tether sister chromatids. Smc3p acetylation is induced in S phase after the chromatin loading of cohesin and is suppressed in G(1) and G(2)/M. Smc3 head acetylation and its cell cycle regulation provide important insights into the biology and mechanism of cohesion establishment.

MeSH Categories: Acetylation, Acetyltransferases/genetics/*metabolism, Amino Acid Sequence, Amino Acid Substitution, Cell Cycle Proteins/chemistry/genetics/*metabolism, Cell Division, Chromatids/*physiology, Chromatin/metabolism, Chromosomal Proteins, Non-Histone/chemistry/genetics/*metabolism, Chromosomes, Fungal/*physiology, G1 Phase, G2 Phase, Immunoprecipitation, Lysine/metabolism, Molecular Sequence Data, Mutation, Nuclear Proteins/genetics/*metabolism, Protein Structure, Tertiary, Proteochondroitin Sulfates/chemistry/genetics/*metabolism, S Phase, Saccharomyces cerevisiae/genetics/growth & development/*physiology, Saccharomyces cerevisiae Proteins/chemistry/genetics/*metabolism

post to: CiteULike

Eco1-dependent cohesin acetylation during establishment of sister chromatid cohesion.

Publication Date: 2008 Jul 25 PMID: 18653893
Authors: Ben-Shahar, T. R. - Heeger, S. - Lehane, C. - East, P. - Flynn, H. - Skehel, M. - Uhlmann, F.
Journal: Science

Replicated chromosomes are held together by the chromosomal cohesin complex from the time of their synthesis in S phase onward. This requires the replication fork-associated acetyl transferase Eco1, but Eco1's mechanism of action is not known. We identified spontaneous suppressors of the thermosensitive eco1-1 allele in budding yeast. An acetylation-mimicking mutation of a conserved lysine in cohesin's Smc3 subunit makes Eco1 dispensable for cell growth, and we show that Smc3 is acetylated in an Eco1-dependent manner during DNA replication to promote sister chromatid cohesion. A second set of eco1-1 suppressors inactivate the budding yeast ortholog of the cohesin destabilizer Wapl. Our results indicate that Eco1 modifies cohesin to stabilize sister chromatid cohesion in parallel with a cohesion establishment reaction that is in principle Eco1-independent.

MeSH Categories: Acetylation, Acetyltransferases/chemistry/genetics/*metabolism, Alleles, Cell Cycle Proteins/chemistry/genetics/*metabolism, Chromatids/*physiology, Chromosomal Proteins, Non-Histone/chemistry/genetics/*metabolism, Chromosomes, Fungal/*physiology, DNA Repair, DNA Replication, DNA, Fungal/metabolism, Mutation, Nuclear Proteins/chemistry/genetics/*metabolism, Protein Subunits/chemistry/genetics/metabolism, Proteochondroitin Sulfates/chemistry/genetics/*metabolism, S Phase, Saccharomyces cerevisiae/genetics/growth & development/*physiology, Saccharomyces cerevisiae Proteins/chemistry/genetics/*metabolism, Suppression, Genetic

post to: CiteULike

One-third of reef-building corals face elevated extinction risk from climate change and local impacts.

Publication Date: 2008 Jul 25 PMID: 18653892
Authors: Carpenter, K. E. - Abrar, M. - Aeby, G. - Aronson, R. B. - Banks, S. - Bruckner, A. - Chiriboga, A. - Cortes, J. - Delbeek, J. C. - Devantier, L. - Edgar, G. J. - Edwards, A. J. - Fenner, D. - Guzman, H. M. - Hoeksema, B. W. - Hodgson, G. - Johan, O. - Licuanan, W. Y. - Livingstone, S. R. - Lovell, E. R. - Moore, J. A. - Obura, D. O. - Ochavillo, D. - Polidoro, B. A. - Precht, W. F. - Quibilan, M. C. - Reboton, C. - Richards, Z. T. - Rogers, A. D. - Sanciangco, J. - Sheppard, A. - Sheppard, C. - Smith, J. - Stuart, S. - Turak, E. - Veron, J. E. - Wallace, C. - Weil, E. - Wood, E.
Journal: Science

The conservation status of 845 zooxanthellate reef-building coral species was assessed by using International Union for Conservation of Nature Red List Criteria. Of the 704 species that could be assigned conservation status, 32.8% are in categories with elevated risk of extinction. Declines in abundance are associated with bleaching and diseases driven by elevated sea surface temperatures, with extinction risk further exacerbated by local-scale anthropogenic disturbances. The proportion of corals threatened with extinction has increased dramatically in recent decades and exceeds that of most terrestrial groups. The Caribbean has the largest proportion of corals in high extinction risk categories, whereas the Coral Triangle (western Pacific) has the highest proportion of species in all categories of elevated extinction risk. Our results emphasize the widespread plight of coral reefs and the urgent need to enact conservation measures.

MeSH Categories: Animals, *Anthozoa/classification/growth & development, Caribbean Region, *Climate, Conservation of Natural Resources, *Ecosystem, *Extinction, Biological, Greenhouse Effect, Indian Ocean, Pacific Ocean, Risk Assessment, *Seawater, Species Specificity, Temperature

post to: CiteULike

BSKs mediate signal transduction from the receptor kinase BRI1 in Arabidopsis.

Publication Date: 2008 Jul 25 PMID: 18653891
Authors: Tang, W. - Kim, T. W. - Oses-Prieto, J. A. - Sun, Y. - Deng, Z. - Zhu, S. - Wang, R. - Burlingame, A. L. - Wang, Z. Y.
Journal: Science

Brassinosteroids (BRs) bind to the extracellular domain of the receptor kinase BRI1 to activate a signal transduction cascade that regulates nuclear gene expression and plant development. Many components of the BR signaling pathway have been identified and studied in detail. However, the substrate of BRI1 kinase that transduces the signal to downstream components remains unknown. Proteomic studies of plasma membrane proteins lead to the identification of three homologous BR-signaling kinases (BSK1, BSK2, and BSK3). The BSKs are phosphorylated by BRI1 in vitro and interact with BRI1 in vivo. Genetic and transgenic studies demonstrate that the BSKs represent a small family of kinases that activate BR signaling downstream of BRI1. These results demonstrate that BSKs are the substrates of BRI1 kinase that activate downstream BR signal transduction.

MeSH Categories: Amino Acid Sequence, Arabidopsis/enzymology/genetics/*metabolism, Arabidopsis Proteins/chemistry/genetics/*metabolism, Cell Membrane/metabolism, Cholestanols/metabolism/pharmacology, Molecular Sequence Data, Mutagenesis, Insertional, Phosphorylation, Plants, Genetically Modified, Protein Kinases/chemistry/genetics/*metabolism, Protein Structure, Tertiary, Proteomics, Recombinant Fusion Proteins/metabolism, *Signal Transduction, Steroids, Heterocyclic/metabolism/pharmacology

post to: CiteULike

Enhancement of thermoelectric efficiency in PbTe by distortion of the electronic density of states.

Publication Date: 2008 Jul 25 PMID: 18653890
Authors: Heremans, J. P. - Jovovic, V. - Toberer, E. S. - Saramat, A. - Kurosaki, K. - Charoenphakdee, A. - Yamanaka, S. - Snyder, G. J.
Journal: Science

The efficiency of thermoelectric energy converters is limited by the material thermoelectric figure of merit (zT). The recent advances in zT based on nanostructures limiting the phonon heat conduction is nearing a fundamental limit: The thermal conductivity cannot be reduced below the amorphous limit. We explored enhancing the Seebeck coefficient through a distortion of the electronic density of states and report a successful implementation through the use of the thallium impurity levels in lead telluride (PbTe). Such band structure engineering results in a doubling of zT in p-type PbTe to above 1.5 at 773 kelvin. Use of this new physical principle in conjunction with nanostructuring to lower the thermal conductivity could further enhance zT and enable more widespread use of thermoelectric systems.

post to: CiteULike

Did cooling oceans trigger Ordovician biodiversification? Evidence from conodont thermometry.

Publication Date: 2008 Jul 25 PMID: 18653889
Authors: Trotter, J. A. - Williams, I. S. - Barnes, C. R. - Lecuyer, C. - Nicoll, R. S.
Journal: Science

The Ordovician Period, long considered a supergreenhouse state, saw one of the greatest radiations of life in Earth's history. Previous temperature estimates of up to approximately 70 degrees C have spawned controversial speculation that the oxygen isotopic composition of seawater must have evolved over geological time. We present a very different global climate record determined by ion microprobe oxygen isotope analyses of Early Ordovician-Silurian conodonts. This record shows a steady cooling trend through the Early Ordovician reaching modern equatorial temperatures that were sustained throughout the Middle and Late Ordovician. This favorable climate regime implies not only that the oxygen isotopic composition of Ordovician seawater was similar to that of today, but also that climate played an overarching role in promoting the unprecedented increases in biodiversity that characterized this period.

MeSH Categories: Animals, Apatites, *Biodiversity, *Climate, *Fossils, Invertebrates, Oceans and Seas, Oxygen Isotopes/analysis, *Seawater, Temperature, *Vertebrates

post to: CiteULike

Phase transitions of Dirac electrons in bismuth.

Publication Date: 2008 Jul 25 PMID: 18653888
Authors: Li, L. - Checkelsky, J. G. - Hor, Y. S. - Uher, C. - Hebard, A. F. - Cava, R. J. - Ong, N. P.
Journal: Science

The Dirac Hamiltonian, which successfully describes relativistic fermions, applies equally well to electrons in solids with linear energy dispersion, for example, in bismuth and graphene. A characteristic of these materials is that a magnetic field less than 10 tesla suffices to force the Dirac electrons into the lowest Landau level, with resultant strong enhancement of the Coulomb interaction energy. Moreover, the Dirac electrons usually come with multiple flavors or valley degeneracy. These ingredients favor transitions to a collective state with novel quantum properties in large field. By using torque magnetometry, we have investigated the magnetization of bismuth to fields of 31 tesla. We report the observation of sharp field-induced phase transitions into a state with striking magnetic anisotropy, consistent with the breaking of the threefold valley degeneracy.

post to: CiteULike

Entangling the spatial properties of laser beams.

Publication Date: 2008 Jul 25 PMID: 18653887
Authors: Wagner, K. - Janousek, J. - Delaubert, V. - Zou, H. - Harb, C. - Treps, N. - Morizur, J. F. - Lam, P. K. - Bachor, H. A.
Journal: Science

Position and momentum were the first pair of conjugate observables explicitly used to illustrate the intricacy of quantum mechanics. We have extended position and momentum entanglement to bright optical beams. Applications in optical metrology and interferometry require the continuous measurement of laser beams, with the accuracy fundamentally limited by the uncertainty principle. Techniques based on spatial entanglement of the beams could overcome this limit, and high-quality entanglement is required. We report a value of 0.51 for inseparability and 0.62 for the Einstein-Podolsky-Rosen criterion, both normalized to a classical limit of 1. These results are a conclusive optical demonstration of macroscopic position and momentum quantum entanglement and also confirm that the resources for spatial multimode protocols are available.

post to: CiteULike

An Argonaute transports siRNAs from the cytoplasm to the nucleus.

Publication Date: 2008 Jul 25 PMID: 18653886
Authors: Guang, S. - Bochner, A. F. - Pavelec, D. M. - Burkhart, K. B. - Harding, S. - Lachowiec, J. - Kennedy, S.
Journal: Science

Ribonucleoprotein complexes consisting of Argonaute-like proteins and small regulatory RNAs function in a wide range of biological processes. Many of these small regulatory RNAs are predicted to act, at least in part, within the nucleus. We conducted a genetic screen to identify factors essential for RNA interference (RNAi) in nuclei of Caenorhabditis elegans and identified the Argonaute protein NRDE-3. In the absence of small interfering RNAs (siRNAs), NRDE-3 resides in the cytoplasm. NRDE-3 binds siRNAs generated by RNA-dependent RNA polymerases acting on messenger RNA templates in the cytoplasm and redistributes to the nucleus. Nuclear redistribution of NRDE-3 requires a functional nuclear localization signal, is required for nuclear RNAi, and results in NRDE-3 association with nuclear-localized nascent transcripts. Thus, specific Argonaute proteins can transport specific classes of small regulatory RNAs to distinct cellular compartments to regulate gene expression.

MeSH Categories: Active Transport, Cell Nucleus, Animals, Caenorhabditis elegans/embryology/*genetics/growth &, development/*metabolism, Caenorhabditis elegans Proteins/chemistry/genetics/*metabolism, Cell Nucleus/*metabolism, Cytoplasm/*metabolism, Genes, Helminth, Mutation, Nuclear Localization Signals, Protein Structure, Tertiary, *RNA Interference, RNA Precursors/genetics/metabolism, RNA Replicase/metabolism, RNA, Double-Stranded/chemistry/genetics/metabolism, RNA, Helminth/chemistry/genetics/metabolism, RNA, Messenger/genetics/metabolism, RNA, Small Interfering/chemistry/genetics/*metabolism, RNA-Binding Proteins/chemistry/genetics/*metabolism, Up-Regulation

post to: CiteULike

A quantitative link between recycling and osmium isotopes.

Publication Date: 2008 Jul 25 PMID: 18653885
Authors: Sobolev, A. V. - Hofmann, A. W. - Brugmann, G. - Batanova, V. G. - Kuzmin, D. V.
Journal: Science

Recycled subducted ocean crust has been traced by elevated 187Os/188Os in some studies and by high nickel and low manganese contents in others. Here, we show that these tracers are linked for Quaternary lavas of Iceland, strengthening the recycling model. An estimate of the osmium isotopic composition of both the recycled crust and the mantle peridotite implies that Icelandic Quaternary lavas are derived in part from an ancient crustal component with model ages between 1.1 _ 109 and 1.8 _ 109 years and from a peridotitic end-member close to present-day oceanic mantle.

post to: CiteULike

Whither or wither microbicides?

Publication Date: 2008 Jul 25 PMID: 18653884
Authors: Grant, R. M. - Hamer, D. - Hope, T. - Johnston, R. - Lange, J. - Lederman, M. M. - Lieberman, J. - Miller, C. J. - Moore, J. P. - Mosier, D. E. - Richman, D. D. - Schooley, R. T. - Springer, M. S. - Veazey, R. S. - Wainberg, M. A.
Journal: Science

After disappointing results from all efficacy trials conducted to date, the field of microbicides research now faces substantial challenges. Poor coordination among interested parties and the choice of nonvalidated scientific targets for phase III studies have hampered progress and created mistrust about the use of microbicides as a method to prevent HIV-1 sexual transmission. Although new promising strategies are available, there will need to be serious reappraisals of how decisions are made to advance the next generations of candidates into clinical trials, and the use of appropriate animal models in this process will be critical.

MeSH Categories: Administration, Intravaginal, Animals, Anti-HIV Agents/*administration & dosage/pharmacology/therapeutic use, Anti-Infective Agents, Local/*administration &, dosage/pharmacology/therapeutic use, Clinical Trials as Topic, Disease Models, Animal, Drug Evaluation, Preclinical, Drug Therapy, Combination, Female, HIV Infections/drug therapy/*prevention & control/transmission, HIV-1/*drug effects, Humans, Male, Patient Compliance, Polymers/*administration & dosage/pharmacology/therapeutic use, Primates, Reverse Transcriptase Inhibitors/*administration &, dosage/pharmacology/therapeutic use, Vaginal Diseases/drug therapy/*prevention & control

post to: CiteULike

HIV vaccine research: the way forward.

Publication Date: 2008 Jul 25 PMID: 18653883
Authors: Fauci, A. S. - Johnston, M. I. - Dieffenbach, C. W. - Burton, D. R. - Hammer, S. M. - Hoxie, J. A. - Martin, M. - Overbaugh, J. - Watkins, D. I. - Mahmoud, A. - Greene, W. C.
Journal: Science

The need to broaden research directed at answering fundamental questions in HIV vaccine discovery through laboratory, nonhuman primate (NHP), and clinical research has recently been emphasized. In addition, the importance of attracting and retaining young researchers, developing better NHP models, and more closely linking NHP and clinical research is being stressed. In an era of a level budget for biomedical research at the U.S. National Institutes of Health (NIH), HIV/AIDS vaccine research efforts will need to be carefully prioritized such that resources to energize HIV vaccine discovery can be identified. This article summarizes progress and challenges in HIV vaccine research, the priorities arising from a recent summit at NIAID, and the actions needed, some already under way, to address those priorities.

MeSH Categories: *AIDS Vaccines/economics/immunology, Animals, *Biomedical Research/economics, Controlled Clinical Trials as Topic, Disease Models, Animal, Financing, Government, HIV/immunology/physiology, HIV Antibodies/immunology, HIV Infections/immunology/*prevention & control/virology, Humans, Male, National Institute of Allergy and Infectious Diseases (U.S.)/economics, Primates, Research Support as Topic, T-Lymphocytes/immunology, United States, Virus Replication

post to: CiteULike

HIV/AIDS. Botswana's success comes at steep cost.

Publication Date: 2008 Jul 25 PMID: 18653882
Authors: Cohen, J.
Journal: Science

MeSH Categories: Acquired Immunodeficiency Syndrome/drug therapy/economics/prevention &, control, Anti-HIV Agents/economics/*supply & distribution/therapeutic use, Botswana/epidemiology, Financing, Government, Financing, Organized, HIV Infections/*drug therapy/economics/epidemiology/*prevention & control, Humans, Prevalence, Private Sector, Public Sector

post to: CiteULike

HIV/AIDS. The Global Fund's best friend?

Publication Date: 2008 Jul 25 PMID: 18653881
Authors: Cohen, J.
Journal: Science

MeSH Categories: Acquired Immunodeficiency Syndrome/*economics, Anti-HIV Agents/*economics, *Financing, Organized, Humans, *International Cooperation, *Periodicals as Topic, Private Sector, Public Sector

post to: CiteULike

HIV/AIDS. The high cost of stolen funds.

Publication Date: 2008 Jul 25 PMID: 18653880
Authors: Cohen, J.
Journal: Science

MeSH Categories: Anti-HIV Agents/*economics/supply & distribution/therapeutic use, *Financing, Organized, HIV Infections/drug therapy/*economics, Humans, International Cooperation, Private Sector, Public Sector, *Theft, Uganda

post to: CiteULike

HIV/AIDS. Uganda confronts corruption, slowly.

Publication Date: 2008 Jul 25 PMID: 18653879
Authors: Cohen, J.
Journal: Science

MeSH Categories: Acquired Immunodeficiency Syndrome/drug therapy/economics, *Financing, Organized, *Fraud, HIV Infections/drug therapy/*economics/prevention & control, Humans, International Cooperation, Private Sector, Public Sector, *Theft, Uganda

post to: CiteULike

HIV/AIDS. Where have all the dollars gone?

Publication Date: 2008 Jul 25 PMID: 18653878
Authors: Cohen, J.
Journal: Science

MeSH Categories: Acquired Immunodeficiency Syndrome/economics, *Bibliometrics, *Financing, Government, HIV Infections/*economics, Humans, National Institutes of Health (U.S.)/*economics, *Research Support as Topic, United States

post to: CiteULike

HIV/AIDS. Bang for the buck.

Publication Date: 2008 Jul 25 PMID: 18653877
Authors: Cohen, J.
Journal: Science

MeSH Categories: Acquired Immunodeficiency Syndrome/*economics/epidemiology/virology, Budgets, Cohort Studies, Databases, Factual/*economics, Financing, Government, *HIV/genetics/immunology, Humans, Indicators and Reagents, Multicenter Studies as Topic, National Institute of Allergy and Infectious Diseases (U.S.)/*economics, *Research Support as Topic, United States

post to: CiteULike

HIV/AIDS. The great funding surge.

Publication Date: 2008 Jul 25 PMID: 18653876
Authors: Cohen, J.
Journal: Science

MeSH Categories: Acquired Immunodeficiency Syndrome/drug therapy/economics/prevention &, control, Anti-HIV Agents/*economics/supply & distribution/therapeutic use, Developed Countries/economics, Developing Countries/economics, Financial Support, Financing, Government, *Financing, Organized, Foundations, HIV Infections/drug therapy/*economics/prevention & control, Humans, International Cooperation, Research Support as Topic, United Nations, United States

post to: CiteULike

HIV/AIDS: money matters.

Publication Date: 2008 Jul 25 PMID: 18653875
Authors: Roberts, L. - Jasny, B.
Journal: Science

MeSH Categories: AIDS Vaccines/economics, Acquired Immunodeficiency Syndrome/drug therapy/economics, Anti-HIV Agents/*economics, Biomedical Research/*economics, Budgets, Financing, Government, HIV Infections/drug therapy/*economics, Humans, International Cooperation, National Institutes of Health (U.S.)/economics, *Research Support as Topic, United States

post to: CiteULike

Studying atomic structures by aberration-corrected transmission electron microscopy.

Publication Date: 2008 Jul 25 PMID: 18653874
Authors: Urban, K. W.
Journal: Science

Seventy-five years after its invention, transmission electron microscopy has taken a great step forward with the introduction of aberration-corrected electron optics. An entirely new generation of instruments enables studies in condensed-matter physics and materials science to be performed at atomic-scale resolution. These new possibilities are meeting the growing demand of nanosciences and nanotechnology for the atomic-scale characterization of materials, nanosynthesized products and devices, and the validation of expected functions. Equipped with electron-energy filters and electron-energy-loss spectrometers, the new instruments allow studies not only of structure but also of elemental composition and chemical bonding. The energy resolution is about 100 milli-electron volts, and the accuracy of spatial measurements has reached a few picometers. However, understanding the results is generally not straightforward and only possible with extensive quantum-mechanical computer calculations.

post to: CiteULike

Materials science. Bulk metallic glasses.

Publication Date: 2008 Jul 25 PMID: 18653873
Authors: Byrne, C. J. - Eldrup, M.
Journal: Science

post to: CiteULike

Physics. Let quantum mechanics improve your images.

Publication Date: 2008 Jul 25 PMID: 18653872
Authors: Boyd, R. W.
Journal: Science

post to: CiteULike

Biochemistry. Cargo load reduction.

Publication Date: 2008 Jul 25 PMID: 18653871
Authors: Braakman, I. - Otsu, M.
Journal: Science

MeSH Categories: Amino Acid Motifs, Animals, Endoplasmic Reticulum/*metabolism, Glycoproteins/metabolism, HSP40 Heat-Shock Proteins/chemistry/genetics/*metabolism, Heat-Shock Proteins/metabolism, Humans, Membrane Proteins/metabolism, Mice, Molecular Chaperones/chemistry/genetics/*metabolism, Oxidation-Reduction, Protein Binding, Protein Disulfide-Isomerase/metabolism, Protein Folding, Protein Structure, Tertiary, Protein Transport, Proteins/chemistry/*metabolism

post to: CiteULike

Biochemistry. A natural choice for activating hydrogen.

Publication Date: 2008 Jul 25 PMID: 18653870
Authors: Armstrong, F. A. - Fontecilla-Camps, J. C.
Journal: Science

MeSH Categories: Binding Sites, Carbon Dioxide/metabolism, Carbon Monoxide/chemistry/metabolism, Crystallography, X-Ray, Cyanides/chemistry/metabolism, Hydrogen/*metabolism, Hydrogenase/*chemistry/*metabolism, Iron/chemistry, Ligands, Methane/*biosynthesis, Oxidation-Reduction

post to: CiteULike

Physics. Elemental complexity.

Publication Date: 2008 Jul 25 PMID: 18653869
Authors: Behnia, K.
Journal: Science

post to: CiteULike

Molecular biology. RNA interference in the nucleus.

Publication Date: 2008 Jul 25 PMID: 18653868
Authors: Meister, G.
Journal: Science

MeSH Categories: Active Transport, Cell Nucleus, Animals, Caenorhabditis elegans/*genetics/metabolism, Caenorhabditis elegans Proteins/chemistry/genetics/*metabolism, Cell Nucleus/genetics/*metabolism, Cytoplasm/metabolism, *RNA Interference, RNA Replicase/metabolism, RNA, Helminth/metabolism, RNA, Small Interfering/*metabolism, RNA-Binding Proteins/chemistry/genetics/*metabolism

post to: CiteULike

Diversity. Gender similarities characterize math performance.

Publication Date: 2008 Jul 25 PMID: 18653867
Authors: Hyde, J. S. - Lindberg, S. M. - Linn, M. C. - Ellis, A. B. - Williams, C. C.
Journal: Science

MeSH Categories: *Achievement, Adolescent, Aptitude, Career Choice, Child, Educational Measurement, Ethnic Groups, Female, Humans, *Learning, Male, *Mathematics, Problem Solving, *Sex Characteristics

post to: CiteULike

Comment on "Major Australian-Antarctic plate reorganization at Hawaiian-Emperor bend time".

Publication Date: 2008 Jul 25 PMID: 18653866
Authors: Tikku, A. A. - Direen, N. G.
Journal: Science

Whittaker et al. (Reports, 5 October 2007, p. 83) presented reconstructions for Australia and Antarctica showing a change in relative plate motion approximately 53 million years ago, coincident with an inferred major global plate reorganization. This comment addresses problematic areas in their assumptions and the geological consequences of their reconstructions.

post to: CiteULike

Leave regulation to the FDA.

Publication Date: 2008 Jul 25 PMID: 18653865
Authors: Hughes, O. C.
Journal: Science

MeSH Categories: Drug Approval, *Jurisprudence, *Liability, Legal, United States, United States Food and Drug Administration/*legislation & jurisprudence

post to: CiteULike

Italy not alone in science system woes.

Publication Date: 2008 Jul 25 PMID: 18653864
Authors: Vendrame, M.
Journal: Science

MeSH Categories: *Career Mobility, *Faculty, Italy, *Research Personnel/economics, Salaries and Fringe Benefits, United States

post to: CiteULike

Doubts about GM crops.

Publication Date: 2008 Jul 25 PMID: 18653863
Authors: Mitchell, P.
Journal: Science

MeSH Categories: *Agriculture, Crops, Agricultural/*genetics, *Plants, Genetically Modified

post to: CiteULike

Retraction.

Publication Date: 2008 Jul 25 PMID: 18653862
Authors: Geremia, J. M. - Stockton, J. K. - Mabuchi, H.
Journal: Science

post to: CiteULike

Behavior Genetics Association. Do good sperm predict a good brain?

Publication Date: 2008 Jul 25 PMID: 18653861
Authors: Holden, C.
Journal: Science

MeSH Categories: Adult, Humans, *Intelligence, Male, Sperm Count, Sperm Motility, Spermatozoa/*physiology

post to: CiteULike

Behavior Genetics Association. The sociable brain.

Publication Date: 2008 Jul 25 PMID: 18653860
Authors: Holden, C.
Journal: Science

MeSH Categories: Brain/*anatomy & histology, Cephalometry, Female, *Friends, Head/anatomy & histology, Humans, Intelligence, Male, Organ Size, Personality, *Social Behavior

post to: CiteULike

Behavior Genetics Association. Voting: in your genes?

Publication Date: 2008 Jul 25 PMID: 18653859
Authors: Holden, C.
Journal: Science

MeSH Categories: *Genes, Genetics, Behavioral, Humans, Personality/genetics, *Politics, Twin Studies as Topic, Twins, Dizygotic, Twins, Monozygotic

post to: CiteULike

Planetary science. Water everywhere on early Mars but only for a geologic moment?

Publication Date: 2008 Jul 25 PMID: 18653858
Authors: Kerr, R. A.
Journal: Science

MeSH Categories: Extraterrestrial Environment, *Mars, *Water

post to: CiteULike

U.S. research earmarks. Building a scientific legacy on a controversial foundation.

Publication Date: 2008 Jul 25 PMID: 18653857
Authors: Mervis, J.
Journal: Science

MeSH Categories: Academies and Institutes/*economics, Aging, *Financing, Government, Humans, Nutritional Sciences, Radioactive Waste, *Research Support as Topic, United States, United States Department of Agriculture/economics, Universities/*economics

post to: CiteULike

Astronomy. From atop a mountain, a deeper look at the Sun.

Publication Date: 2008 Jul 25 PMID: 18653856
Authors: Bhattacharjee, Y.
Journal: Science

post to: CiteULike

U.S. environmental policy. EPA calls for more studies on health risks of climate change.

Publication Date: 2008 Jul 25 PMID: 18653855
Authors: Kintisch, E.
Journal: Science

MeSH Categories: Budgets, Centers for Disease Control and Prevention (U.S.)/economics, *Climate, Greenhouse Effect, *Health, Humans, Population Surveillance, United States, *United States Environmental Protection Agency

post to: CiteULike

Wenchuan earthquake. Lessons of disasters past could guide Sichuan's revival.

Publication Date: 2008 Jul 25 PMID: 18653854
Authors: Stone, R.
Journal: Science

post to: CiteULike

Scientific meetings. Europe's science gathering draws crowds and long-term funds.

Publication Date: 2008 Jul 25 PMID: 18653853
Authors: Enserink, M.
Journal: Science

MeSH Categories: *Congresses as Topic/organization & administration, Europe, *Science

post to: CiteULike

Science in Japan. Paper retraction puts focus on informed consent rules.

Publication Date: 2008 Jul 25 PMID: 18653852
Authors: Normile, D.
Journal: Science

MeSH Categories: Biomedical Research/*ethics, Editorial Policies, *Ethics Committees, Research, Humans, *Informed Consent, Japan, Retraction of Publication as Topic

post to: CiteULike

Scientific misconduct. New Purdue panel faults bubble fusion pioneer.

Publication Date: 2008 Jul 25 PMID: 18653851
Authors: Service, R. F.
Journal: Science

post to: CiteULike

AIDS vaccine research. Thumbs down on expensive, hotly debated trial of NIH AIDS vaccine.

Publication Date: 2008 Jul 25 PMID: 18653850
Authors: Cohen, J.
Journal: Science

MeSH Categories: *AIDS Vaccines/economics, Acquired Immunodeficiency Syndrome/*prevention & control, *Clinical Trials as Topic/economics, Costs and Cost Analysis, Humans, National Institute of Allergy and Infectious Diseases (U.S.)/economics, United States

post to: CiteULike

HIV/AIDS in Latin America.

Publication Date: 2008 Jul 25 PMID: 18653849
Authors: Soto-Ramirez, L. E.
Journal: Science

MeSH Categories: Acquired Immunodeficiency Syndrome/epidemiology/prevention & control, Anti-HIV Agents/supply & distribution/*therapeutic use, Caribbean Region/epidemiology, Disease Outbreaks, *HIV Infections/drug therapy/epidemiology/prevention & control, Health Services Accessibility, Humans, Latin America/epidemiology

post to: CiteULike

The Elusive Onset of Geomagnetic Substorms.

Publication Date: 2008 Jul 24 PMID: 18653848
Authors: Petrukovich, A. A.
Journal: Science

The triggers of geomagnetic substorms, and their connection to auroral displays, have been sought in data from a satellite fleet and ground-based observations.

post to: CiteULike

Human CHN1 Mutations Hyperactivate {alpha}2-Chimaerin and Cause Duane's Retraction Syndrome.

Publication Date: 2008 Jul 24 PMID: 18653847
Authors: Miyake, N. - Chilton, J. - Psatha, M. - Cheng, L. - Andrews, C. - Chan, W. M. - Law, K. - Crosier, M. - Lindsay, S. - Cheung, M. - Allen, J. - Gutowski, N. J. - Ellard, S. - Young, E. - Iannaccone, A. - Appukuttan, B. - Stout, J. T. - Christiansen, S. - Ciccarelli, M. L. - Baldi, A. - Campioni, M. - Zenteno, J. C. - Davenport, D. - Mariani, L. E. - Sahin, M. - Guthrie, S. - Engle, E. C.
Journal: Science

Duane's retraction syndrome (DRS) is a complex congenital eye movement disorder caused by aberrant innervation of the extraocular muscles by axons of brainstem motor neurons. Studying families with a variant form of the disorder (DURS2-DRS), we have identified causative heterozygous missense mutations in CHN1, a gene on chromosome 2q31 that encodes alpha2-chimaerin, a RacGAP signaling protein previously implicated in the pathfinding of corticospinal axons in mice. We show that these are gain-of-function mutations that increase alpha2-chimaerin RacGAP activity in vitro. Several of the mutations appear to enhance alpha2-chimaerin translocation to the cell membrane or enhance its ability to self-associate. Expression of mutant alpha2-chimaerin constructs in chick embryos resulted in failure of oculomotor axons to innervate their target extraocular muscles. We conclude that alpha2-chimaerin has a critical developmental function in ocular motor axon pathfinding.

post to: CiteULike

The Metamorphosis of Supernova SN 2008D/XRF 080109: A Link Between Supernovae and GRBs/Hypernovae.

Publication Date: 2008 Jul 24 PMID: 18653846
Authors: Mazzali, P. A. - Valenti, S. - Della Valle, M. - Chincarini, G. - Sauer, D. N. - Benetti, S. - Pian, E. - Piran, T. - D'Elia, V. - Elias-Rosa, N. - Margutti, R. - Pasotti, F. - Antonelli, L. A. - Bufano, F. - Campana, S. - Cappellaro, E. - Covino, S. - D'Avanzo, P. - Fiore, F. - Fugazza, D. - Gilmozzi, R. - Hunter, D. - Maguire, K. - Maiorano, E. - Marziani, P. - Masetti, N. - Mirabel, F. - Navasardyan, H. - Nomoto, K. - Palazzi, E. - Pastorello, A. - Panagia, N. - Pellizza, L. J. - Sari, R. - Smartt, S. - Tagliaferri, G. - Tanaka, M. - Taubenberger, S. - Tominaga, N. - Trundle, C. - Turatto, M.
Journal: Science

The only supernovae (SNe) to have shown early gamma-ray or x-ray emission thus far are overenergetic, broad-lined type Ic SNe (hypernovae, HNe). Recently, SN 2008D has shown several novel features: (i) weak x-ray flash (XRF); (ii) an early, narrow optical peak; (iii) disappearance of the broad lines typical of SN Ic HNe; and (iv) development of He lines as in SNe Ib. Detailed analysis shows that SN 2008D was not a normal SN: Its explosion energy (E approximately 6 x 10(51) erg) and ejected mass (~7 Mmiddle dot in circle) are intermediate between normal SNe Ibc and HNe. We derive that SN 2008D was originally a ~30 Mmiddle dot in circle star. When it collapsed, a black hole formed and a weak, mildly relativistic jet was produced, which caused the XRF. SN 2008D is probably among the weakest explosions that produce relativistic jets. Inner engine activity appears to be present whenever massive stars collapse to black holes.

post to: CiteULike

Tail Reconnection Triggering Substorm Onset.

Publication Date: 2008 Aug 5 PMID: 18653845
Authors: Angelopoulos, V. - McFadden, J. P. - Larson, D. - Carlson, C. W. - Mende, S. B. - Frey, H. - Phan, T. - Sibeck, D. G. - Glassmeier, K. H. - Auster, U. - Donovan, E. - Mann, I. R. - Rae, I. J. - Russell, C. T. - Runov, A. - Zhou, X. Z. - Kepko, L.
Journal: Science

Magnetospheric substorms explosively release solar wind energy previously stored in Earth's magnetotail, encompassing the entire magnetosphere and producing spectacular auroral displays. It has been unclear whether a substorm is triggered by a disruption of the electrical current flowing across the near-Earth magnetotail, at ~10 RE (RE = Earth Radius, or 6374 km), or by the process of magnetic reconnection typically seen farther out in the magnetotail, at ~20 to 30 RE. We report on simultaneous measurements in the magnetotail at multiple distances, at the time of substorm onset. Reconnection was observed at 20 RE, at least 1.5 min before auroral intensification, at least 2 min before substorm expansion, and about 3 min before near-Earth current disruption. These results demonstrate that substorms are likely initiated by tail reconnection.

post to: CiteULike

Orbitofrontal dysfunction in patients with obsessive-compulsive disorder and their unaffected relatives.

Publication Date: 2008 Jul 18 PMID: 18635808
Authors: Chamberlain, S. R. - Menzies, L. - Hampshire, A. - Suckling, J. - Fineberg, N. A. - del Campo, N. - Aitken, M. - Craig, K. - Owen, A. M. - Bullmore, E. T. - Robbins, T. W. - Sahakian, B. J.
Journal: Science

Obsessive-compulsive disorder (OCD) is characterized by repetitive thoughts and behaviors associated with underlying dysregulation of frontostriatal circuitry. Central to neurobiological models of OCD is the orbitofrontal cortex, a neural region that facilitates behavioral flexibility after negative feedback (reversal learning). We identified abnormally reduced activation of several cortical regions, including the lateral orbitofrontal cortex, during reversal learning in OCD patients and their clinically unaffected close relatives, supporting the existence of an underlying previously undiscovered endophenotype for this disorder.

MeSH Categories: Adult, Brain Mapping, Family, Female, Frontal Lobe/*physiopathology, Humans, Magnetic Resonance Imaging, Male, Obsessive-Compulsive Disorder/*physiopathology, Prefrontal Cortex/physiopathology, *Reversal Learning

post to: CiteULike

Evolutionary origins for social vocalization in a vertebrate hindbrain-spinal compartment.

Publication Date: 2008 Jul 18 PMID: 18635807
Authors: Bass, A. H. - Gilland, E. H. - Baker, R.
Journal: Science

The macroevolutionary events leading to neural innovations for social communication, such as vocalization, are essentially unexplored. Many fish vocalize during female courtship and territorial defense, as do amphibians, birds, and mammals. Here, we map the neural circuitry for vocalization in larval fish and show that the vocal network develops in a segment-like region across the most caudal hindbrain and rostral spinal cord. Taxonomic analysis demonstrates a highly conserved pattern between fish and all major lineages of vocal tetrapods. We propose that the vocal basis for acoustic communication among vertebrates evolved from an ancestrally shared developmental compartment already present in the early fishes.

MeSH Categories: Animals, Batrachoidiformes/*anatomy & histology/growth & development/physiology, Cerebellum/cytology/growth & development, *Evolution, Motor Neurons/*cytology, Nerve Net/*cytology/growth & development, Neurons/*cytology, Rhombencephalon/*cytology/growth & development, Spinal Cord/*cytology/growth & development, Vagus Nerve/cytology, Vertebrates/anatomy & histology/growth & development/physiology, *Vocalization, Animal

post to: CiteULike

Bottom-up dependent gating of frontal signals in early visual cortex.

Publication Date: 2008 Jul 18 PMID: 18635806
Authors: Ekstrom, L. B. - Roelfsema, P. R. - Arsenault, J. T. - Bonmassar, G. - Vanduffel, W.
Journal: Science

The frontal eye field (FEF) is one of several cortical regions thought to modulate sensory inputs. Moreover, several hypotheses suggest that the FEF can only modulate early visual areas in the presence of a visual stimulus. To test for bottom-up gating of frontal signals, we microstimulated subregions in the FEF of two monkeys and measured the effects throughout the brain with functional magnetic resonance imaging. The activity of higher-order visual areas was strongly modulated by FEF stimulation, independent of visual stimulation. In contrast, FEF stimulation induced a topographically specific pattern of enhancement and suppression in early visual areas, but only in the presence of a visual stimulus. Modulation strength depended on stimulus contrast and on the presence of distractors. We conclude that bottom-up activation is needed to enable top-down modulation of early visual cortex and that stimulus saliency determines the strength of this modulation.

MeSH Categories: Animals, Brain Mapping, Electric Stimulation, Fixation, Ocular, Frontal Lobe/*physiology, Macaca mulatta, Magnetic Resonance Imaging, Male, Photic Stimulation, Saccades, Visual Cortex/*physiology, Visual Pathways

post to: CiteULike

Riboswitches in eubacteria sense the second messenger cyclic di-GMP.

Publication Date: 2008 Jul 18 PMID: 18635805
Authors: Sudarsan, N. - Lee, E. R. - Weinberg, Z. - Moy, R. H. - Kim, J. N. - Link, K. H. - Breaker, R. R.
Journal: Science

Cyclic di-guanosine monophosphate (di-GMP) is a circular RNA dinucleotide that functions as a second messenger in diverse species of bacteria to trigger wide-ranging physiological changes, including cell differentiation, conversion between motile and biofilm lifestyles, and virulence gene expression. However, the mechanisms by which cyclic di-GMP regulates gene expression have remained a mystery. We found that cyclic di-GMP in many bacterial species is sensed by a riboswitch class in messenger RNA that controls the expression of genes involved in numerous fundamental cellular processes. A variety of cyclic di-GMP regulons are revealed, including some riboswitches associated with virulence gene expression, pilus formation, and flagellum biosynthesis. In addition, sequences matching the consensus for cyclic di-GMP riboswitches are present in the genome of a bacteriophage.

MeSH Categories: Aptamers, Nucleotide/*metabolism, Bacillus cereus/genetics/metabolism, Bacteria/*genetics/metabolism, Bacteriophages/genetics, Base Sequence, Clostridium difficile/genetics/metabolism, Cyclic GMP/*analogs & derivatives/metabolism, *Gene Expression Regulation, Bacterial, Genes, Bacterial, Ligands, Molecular Sequence Data, Nucleic Acid Conformation, RNA, Bacterial/chemistry/*metabolism, RNA, Messenger/chemistry/*metabolism, Regulon, *Second Messenger Systems, Vibrio cholerae/genetics/metabolism

post to: CiteULike

Anomalous type 17 response to viral infection by CD8+ T cells lacking T-bet and eomesodermin.

Publication Date: 2008 Jul 18 PMID: 18635804
Authors: Intlekofer, A. M. - Banerjee, A. - Takemoto, N. - Gordon, S. M. - Dejong, C. S. - Shin, H. - Hunter, C. A. - Wherry, E. J. - Lindsten, T. - Reiner, S. L.
Journal: Science

When intracellular pathogens invade mammalian hosts, naive CD8+ T cells differentiate into cytotoxic killers, which lyse infected target cells and secrete cytokines that activate intracellular microbicides. We show that CD8+ T cells deficient in the transcription factors T-bet and eomesodermin (Eomes) fail to differentiate into functional killers required for defense against lymphocytic choriomeningitis virus. Instead, virus-specific CD8+ T cells lacking both T-bet and Eomes differentiate into an interleukin-17-secreting lineage, reminiscent of the helper T cell fate that has been implicated in autoimmunity and extracellular microbial defense. Upon viral infection, mice with T cells lacking both T-bet and Eomes develop a CD8+ T cell-dependent, progressive inflammatory and wasting syndrome characterized by multi-organ infiltration of neutrophils. T-bet and Eomes, thus, ensure that CD8+ T cells adopt an appropriate course of intracellular rather than extracellular destruction.

MeSH Categories: Animals, Antigens, Viral/immunology, Arenaviridae Infections/*immunology/pathology/virology, CD4-Positive T-Lymphocytes/immunology, CD8-Positive T-Lymphocytes/*immunology/*metabolism, Cell Differentiation, Cytotoxicity, Immunologic, Interferon Type II/metabolism, Interleukin-17/*metabolism, Lymphocyte Depletion, *Lymphocytic choriomeningitis virus/immunology/isolation &, purification/physiology, Mice, Mice, Inbred C57BL, Mice, Knockout, T-Box Domain Proteins/deficiency/genetics/*physiology, Virus Replication, Wasting Syndrome/immunology/pathology/virology

post to: CiteULike

Signal-mediated dynamic retention of glycosyltransferases in the Golgi.

Publication Date: 2008 Jul 18 PMID: 18635803
Authors: Tu, L. - Tai, W. C. - Chen, L. - Banfield, D. K.
Journal: Science

Golgi-resident glycosyltransferases are a family of enzymes that sequentially modify glycoproteins in a subcompartment-specific manner. These type II integral membrane proteins are characterized by a short cytoplasmically exposed amino-terminal tail and a luminal enzymatic domain. The cytoplasmic tails play a role in the localization of glycosyltransferases, and coat protein complex I (COPI) vesicle-mediated retrograde transport is also involved in their Golgi localization. However, the tails of these enzymes lack known COPI-binding motifs. Here, we found that Vps74p bound to a pentameric motif present in the cytoplasmic tails of the majority of yeast Golgi-localized glycosyltransferases, as well as to COPI. We propose that Vps74p maintains the steady-state localization of Golgi glycosyltransferases dynamically, by promoting their incorporation into COPI-coated vesicles.

MeSH Categories: Amino Acid Motifs, Amino Acid Sequence, COP-Coated Vesicles/metabolism, Carrier Proteins/*metabolism, Coat Protein Complex I/metabolism, Endoplasmic Reticulum/metabolism, Glycosyltransferases/chemistry/*metabolism, Golgi Apparatus/*metabolism, Molecular Sequence Data, Protein Transport, Recombinant Fusion Proteins/metabolism, Saccharomyces cerevisiae/*metabolism, Saccharomyces cerevisiae Proteins/*metabolism

post to: CiteULike

Four-jointed is a Golgi kinase that phosphorylates a subset of cadherin domains.

Publication Date: 2008 Jul 18 PMID: 18635802
Authors: Ishikawa, H. O. - Takeuchi, H. - Haltiwanger, R. S. - Irvine, K. D.
Journal: Science

The atypical cadherin Fat acts as a receptor for a signaling pathway that regulates growth, gene expression, and planar cell polarity. Genetic studies in Drosophila identified the four-jointed gene as a regulator of Fat signaling. We show that four-jointed encodes a protein kinase that phosphorylates serine or threonine residues within extracellular cadherin domains of Fat and its transmembrane ligand, Dachsous. Four-jointed functions in the Golgi and is the first molecularly defined kinase that phosphorylates protein domains destined to be extracellular. An acidic sequence motif (Asp-Asn-Glu) within Four-jointed was essential for its kinase activity in vitro and for its biological activity in vivo. Our results indicate that Four-jointed regulates Fat signaling by phosphorylating cadherin domains of Fat and Dachsous as they transit through the Golgi.

MeSH Categories: Amino Acid Motifs, Amino Acid Sequence, Animals, Cadherins/chemistry/*metabolism, Cell Adhesion Molecules/chemistry/*metabolism, Cell Line, Drosophila Proteins/chemistry/genetics/*metabolism, Drosophila melanogaster, Electrophoretic Mobility Shift Assay, Glycosylation, Golgi Apparatus/enzymology/*metabolism, Kinetics, Membrane Glycoproteins/chemistry/genetics/*metabolism, Molecular Sequence Data, Mutant Proteins/chemistry/metabolism, Phosphorylation, Protein Kinases/chemistry/genetics/*metabolism, Protein Structure, Tertiary, Recombinant Fusion Proteins/metabolism, Serine/metabolism, Signal Transduction, Threonine/metabolism

post to: CiteULike

The evolution and distribution of species body size.

Publication Date: 2008 Jul 18 PMID: 18635801
Authors: Clauset, A. - Erwin, D. H.
Journal: Science

The distribution of species body size within taxonomic groups exhibits a heavy right tail extending over many orders of magnitude, where most species are much larger than the smallest species. We provide a simple model of cladogenetic diffusion over evolutionary time that omits explicit mechanisms for interspecific competition and other microevolutionary processes, yet fully explains the shape of this distribution. We estimate the model's parameters from fossil data and find that it robustly reproduces the distribution of 4002 mammal species from the late Quaternary. The observed fit suggests that the asymmetric distribution arises from a fundamental trade-off between the short-term selective advantages (Cope's rule) and long-term selective risks of increased species body size in the presence of a taxon-specific lower limit on body size.

MeSH Categories: Animals, *Body Size, Computer Simulation, *Evolution, Extinction, Biological, Fossils, Genetic Speciation, Mammals/*anatomy & histology/classification/physiology, Models, Biological, Selection (Genetics)

post to: CiteULike