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Results 201 - 250 of 1255
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Kronawitter Coleman X - - 2013
The orbital anisotropy of hematite (α-Fe2O3) nanorod arrays, an engineered structure commonly investigated for applications in solar water oxidation photoanodes, is probed using polarization-dependent soft X-ray absorption spectroscopy at the O K-edge and at the Fe L2,3-edge. Thereby the unoccupied states of α-Fe2O3 are examined. In the lowest energy region ...
Sheka Elena F - - 2013
Applied to graphene oxide, the molecular theory of graphene considers its oxide as a final product in the succession of polyderivatives related to a series of oxidation reactions involving different oxidants. The graphene oxide structure is created in the course of a stepwise computational synthesis of polyoxides of the (5,5) ...
Cabral Gabriela - - 2013
Centrosome function in cell division requires their duplication, once, and only once, per cell cycle. Underlying centrosome duplication are alternating cycles of centriole assembly and separation [1]. Work in vertebrates has implicated the cysteine protease separase in anaphase-coupled centriole separation (or disengagement) and identified this as a key step in ...
Phillips Matthew J - - 2013
It is exciting to be living at a time when the big questions in biology can be investigated using modern genetics and computing [1]. Bauzà-Ribot et al.[2] take on one of the fundamental drivers of biodiversity, the effect of continental drift in the formation of the world's biota [3,4], employing ...
Loewith Robbie - - 2013
Cell division, intuitively, is often dependent upon increases in cellular mass and volume. Less obvious is the reciprocal regulation of growth by the cell division cycle. In budding yeast, this link is mediated by the cell-cycle-dependent polarization of actin.
Land Michael F - - 2013
A recent study using two head-mounted cameras has found that, in freely moving rats, eye movements are usually not conjugate, precluding stereopsis, but they maintain a wide region of binocular overlap above the head, presumably to detect flying predators.
Pichaud Franck - - 2013
The Flower protein family is part of a cell-cell communication pathway that regulates cell competition, in which fit cells eliminate less fit neighbors. A new study demonstrates that this pathway can also govern the culling of unwanted neurons during development.
Groen Aaron - - 2013
A new study demonstrates that two microtubule plus end-directed kinesins can oppose each other. The cause of this apparent contradiction is the specific orientation of microtubules on which each motor exerts its force.
Miura Grant I - - 2013
To function properly, the vertebrate heart must navigate challenging periods by utilizing appropriate stress-response pathways. A new study highlights a crucial role for the transcription factor Gata4 in mediating diverse stress responses in the zebrafish heart.
Ferrero David M - - 2013
Male and female mice behave differently when encountering a male. A recent study identifies progesterone receptor-expressing neurons in the hypothalamus that are required for sexual behavior and male aggression. These findings provide insight into how neural circuits control sexually dimorphic behaviors.
Trybus Kathleen M - - 2013
Intracellular transport of motor-driven cargo faces the navigational challenges of a dense, intersecting cytoskeleton and obstacles including organelles. A new study investigates why directed early endosome trafficking is so frequently interrupted, and how pauses play a role in cargo sorting.
Maître Jean-Léon - - 2013
Cadherins are transmembrane proteins that mediate cell-cell adhesion in animals. By regulating contact formation and stability, cadherins play a crucial role in tissue morphogenesis and homeostasis. Here, we review the three major functions of cadherins in cell-cell contact formation and stability. Two of those functions lead to a decrease in ...
Kellogg Elizabeth A - - 2013
The number of humans on earth is increasing, generating concerns about food security and spurring efforts throughout the world to increase the productivity of crops. If a way could be found to increase the yield of crops by, say, 20%, it would have immense impact on global food supplies. Fortunately, ...
Oliveira Raquel A - - 2013
Centriole disengagement is thought to act as a licensing mechanism restricting centrosome duplication to once per cell cycle [1] and to depend on cleavage of the cohesin complex by separase [1-3]. Whether this is a conserved mechanism in eukaryotic cells remains to be determined. We show that artificial cohesin cleavage ...
Barnes David K A - - 2013
The recent collapse of the Antarctic Larson ice shelves revealed a slow growing benthic community on the seabed below. But a revisit just four years later revealed rapid growth of glass sponges. Antarctic continental shelves could become sites of significant carbon sequestration.
Shine Richard - - 2013
A single meal soon after hatching can reverberate through a lizard's entire life. More generally, events early in life may outweigh genetic factors in fashioning an organism's life history traits.
Grant-Downton Robert - - 2013
Pollen formation, while critical for the success of plant reproduction, also represents an important paradigm for differential cellular development within small groups of cells. In Arabidopsis thaliana pollen, the male meiotic product first divides asymmetrically to form a vegetative and a generative (germ) cell, the latter then dividing to generate ...
Bauzà-Ribot Maria M - - 2013
Phillips et al.[1] reply to our finding that genetic divergence between subterranean metacrangonyctid amphipods from opposite shores of the Atlantic is congruent with vicariance by plate tectonics [2]. They highlight three presumed shortcomings in our analyses: first, the third codon positions of the mitochondrial genes used to reconstruct the metacrangonyctid ...
Zhang Qianyi - - 2013
A newly emerged H7N9 virus has caused 132 human infections with 37 deaths in China since 18 February 2013. Control measures in H7N9 virus-positive live poultry markets have reduced the number of infections; however, the character of the virus, including its pandemic potential, remains largely unknown. We systematically analyzed H7N9 ...
Yang Wentian - - 2013
The tyrosine phosphatase SHP2, encoded by PTPN11, is required for the survival, proliferation and differentiation of various cell types. Germline activating mutations in PTPN11 cause Noonan syndrome, whereas somatic PTPN11 mutations cause childhood myeloproliferative disease and contribute to some solid tumours. Recently, heterozygous inactivating mutations in PTPN11 were found in ...
Yefsah Tarik - - 2013
Solitons-solitary waves that maintain their shape as they propagate-occur as water waves in narrow canals, as light pulses in optical fibres and as quantum mechanical matter waves in superfluids and superconductors. Their highly nonlinear and localized nature makes them very sensitive probes of the medium in which they propagate. Here ...
Hollenstein Kaspar - - 2013
Structural analysis of class B G-protein-coupled receptors (GPCRs), cell-surface proteins that respond to peptide hormones, has been restricted to the amino-terminal extracellular domain, thus providing little understanding of the membrane-spanning signal transduction domain. The corticotropin-releasing factor receptor type 1 is a class B receptor which mediates the response to stress ...
Siu Fai Yiu FY Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, - - 2013
Binding of the glucagon peptide to the glucagon receptor (GCGR) triggers the release of glucose from the liver during fasting; thus GCGR plays an important role in glucose homeostasis. Here we report the crystal structure of the seven transmembrane helical domain of human GCGR at 3.4 Å resolution, complemented by ...
Ota Hidetaka - - 2013
Gnetum gnemon is an arboreal dioecious plant that is cultivated in Indonesia. The seeds of this species mainly contain dimeric stilbenoid compounds [gnetin C (1), gnemonoside A (2), and gnemonoside D (3)] along with trans-resveratrol (4). trans-Resveratrol has been reported to have antiaging, anticancer, and antidiabetic effects, as well as ...
Gooszen Hein G - - 2013
Acute pancreatitis remains an unpredictable, potentially lethal disease with significant morbidity and mortality rates. New insights in the pathophysiology of acute pancreatitis have changed management concepts. In the first phase, characterized by a systemic inflammatory response syndrome, organ failure, not related to infection but rather to severe inflammation, dominates the ...
Lee Min Ai - - 2013
The antiproliferative and antitumor activities of 2-hydroxycinnamaldehyde (1), a phenylpropanoid isolated from the bark of Cinnamomum cassia, were investigated using human colorectal cancer cells. Compound 1 exhibited antiproliferative effects in HCT116 colon cancer cells, accompanied by modulation of the Wnt/β-catenin cell signaling pathway. This substance was found also to inhibit ...
Wattana-Amorn Pakorn - - 2013
Menisporopsin A, produced by Menisporopsis theobromae, shows antimalarial, antimycobacterial, and cytotoxic activities. Here, we report the first (13)C incorporations at individual carbons of menisporopsin A using sodium [1-(13)C] and [2-(13)C] acetate. This result indicates that each of the subunits of the pentalactone menisporopsin A is assembled by a polyketide synthase.
Shirouzu Takayuki - - 2013
An optically inactive C-20 bisacetylenic alcohol, (4E,16E)-icosa-4,16-diene-1,19-diyne-3,18-diol, was isolated from a marine sponge Callyspongia sp. as a result of screening of antilymphangiogenic agents from marine invertebrates. An optical resolution using chiral-phase HPLC gave each enantiomer, (-)-1 and (+)-2. Because the natural and synthetic enantiomers 1 and 2 showed different biological ...
Li Jing J Department of Pharmacology, University of Texas Health Science Center at San Antonio, Texas 78229, United - - 2013
The taccalonolides are microtubule stabilizers isolated from plants of the genus Tacca that show potent in vivo antitumor activity and the ability to overcome multiple mechanisms of drug resistance. The most potent taccalonolide identified to date, AJ, is a semisynthetic product generated from the major plant metabolite taccalonolide A in ...
Robertson Sabrina D - - 2013
Central norepinephrine-producing neurons comprise a diverse population of cells differing in anatomical location, connectivity, function and response to disease and environmental insult. The mechanisms that generate this diversity are unknown. Here we elucidate the lineal relationship between molecularly distinct progenitor populations in the developing mouse hindbrain and mature norepinephrine neuron ...
Matta Jose A - - 2013
Disrupted excitatory synapse maturation in GABAergic interneurons may promote neuropsychiatric disorders such as schizophrenia. However, establishing developmental programs for nascent synapses in GABAergic cells is confounded by their sparsity, heterogeneity and late acquisition of subtype-defining characteristics. We investigated synaptic development in mouse interneurons targeting cells by lineage from medial ganglionic ...
Lu Li - - 2013
In the hippocampus, spatial and non-spatial parameters may be represented by a dual coding scheme, in which coordinates in space are expressed by the collective firing locations of place cells and the diversity of experience at these locations is encoded by orthogonal variations in firing rates. Although the spatial signal ...
Dobbin Matthew M - - 2013
Defects in DNA repair have been linked to cognitive decline with age and neurodegenerative disease, yet the mechanisms that protect neurons from genotoxic stress remain largely obscure. We sought to characterize the roles of the NAD(+)-dependent deacetylase SIRT1 in the neuronal response to DNA double-strand breaks (DSBs). We found that ...
Rinke Christian - - 2013
Genome sequencing enhances our understanding of the biological world by providing blueprints for the evolutionary and functional diversity that shapes the biosphere. However, microbial genomes that are currently available are of limited phylogenetic breadth, owing to our historical inability to cultivate most microorganisms in the laboratory. We apply single-cell genomics ...
Schmidt Robert R Department of Psychology, University of Michigan, Ann Arbor, Michigan, - - 2013
Salient cues can prompt the rapid interruption of planned actions. It has been proposed that fast, reactive behavioral inhibition involves specific basal ganglia pathways, and we tested this by comparing activity in multiple rat basal ganglia structures during performance of a stop-signal task. Subthalamic nucleus (STN) neurons exhibited low-latency responses ...
Hunt David L DL Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, - - 2013
NMDA receptors (NMDARs) are classically known as coincidence detectors for the induction of long-term synaptic plasticity and have been implicated in hippocampal CA3 cell-dependent spatial memory functions that likely rely on dynamic cellular ensemble encoding of space. The unique functional properties of both NMDARs and mossy fiber projections to CA3 ...
Yoon Kijung K Center for Learning and Memory, University of Texas at Austin, Austin, Texas, - - 2013
We examined simultaneously recorded spikes from multiple rat grid cells, to explain mechanisms underlying their activity. Among grid cells with similar spatial periods, the population activity was confined to lie close to a two-dimensional (2D) manifold: grid cells differed only along two dimensions of their responses and otherwise were nearly ...
Anderson Emily B EB The Salk Institute for Biological Studies, San Diego, California, USA. - - 2013
Attention improves the encoding of visual stimuli. One mechanism that is implicated in facilitating sensory encoding is the firing of action potentials in bursts. We tested the hypothesis that when spatial attention is directed to a stimulus, this causes an increase in burst firing to the attended stimulus. To the ...
Shou Qingyao - - 2013
Two novel alkaloids (parvifloranines A and B), possessing an unusual 11-carbon skeleton linked with amino acids, were isolated from Geijera parviflora, an endemic Australian Rutaceae. Their structures were elucidated by extensive spectroscopic measurements including 2D NMR analyses. Parvifloranine A was found to be a mixture of two enantiomers, (S)-1 and ...
Tan Karen Co - - 2013
A macrocylic dodecapeptide, cycloforskamide, was isolated from the sea slug Pleurobranchus forskalii, collected off Ishigaki Island, Japan. Its planar structure was deduced by extensive NMR analyses and was further confirmed by MS/MS fragmentation analyses. Finally, the absolute configuration was determined by total hydrolysis and chiral-phase gas chromatographic analysis. This novel ...
Chen Charn-Ying - - 2013
We simultaneously employed grazing incidence small-angle and wide-angle X-ray scattering (GISAXS and GIWAXS) techniques to quantitatively study the structural evolution and kinetic behavior of poly(3-hexylthiophene) (P3HT) crystallization, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) aggregation and amorphous P3HT/PCBM domains from a bulk heterojunction (BHJ) to a thermally unstable structure. The independent phase ...
Cong Hai-Jian - - 2013
Eleven new guanidine alkaloids, plumbagines A-G (2-8) and plumbagosides A-D (9-12), as well as two known analogues (1, 13), were isolated from the aerial parts of Plumbago zeylanica. Their structures were elucidated by spectroscopic analyses including 1D and 2D NMR, MS, IR, and CD methods. The absolute configuration of 1 ...
Blanche S - - 2013
Thirty years after the first descriptions of AIDS in children in May 1983, the risk of viral transmission from mother to child has been reduced to almost zero and the disease in infected children has become an asymptomatic condition, stable in the long-term, thanks to antiretroviral drugs. Unbelievable though it ...
Wang Lu - - 2013
Here, we first provide a facile ultrasonic-assisted synthesis of SnO using SnCl2 and the organic solvent of ethanolamine (ETA). The moderate alkalinity of ETA and ultrasound play very important roles in the synthesis of SnO. After the hydrolysis of the intermediate of ETA-Sn(ii), the as-synthesized SnO nanoclusters undergo assembly, amalgamation, ...
Hirata A - - 2013
Icosahedral order has been suggested as the prevalent atomic motif of supercooled liquids and metallic glasses for more than half a century, because the icosahedron is highly close-packed but is difficult to grow, owing to structure frustration and the lack of translational periodicity. By means of angstrom-beam electron diffraction of ...
Suzuki Jun - - 2013
A classic feature of apoptotic cells is the cell-surface exposure of phosphatidylserine (PtdSer) as an "eat me" signal for engulfment. We show that the Xk-family protein Xkr8 mediates PtdSer exposure in response to apoptotic stimuli. Mouse Xkr8(-/-) cells or human cancer cells in which Xkr8 expression was repressed by hypermethylation ...
Dumortier B - - 2013
The Measles-Mumps-Rubella (MMR) vaccine is often postponed in egg-allergic patients due to fear of anaphylactic reaction at the time of injection of this vaccin produced on egg derivates. However, this vaccine is recommended by health authorities, especially in case of increased measles incidence, and international recommendations indicate that there is ...
Fillinger Laura - - 2013
Over 30% of the Antarctic continental shelf is permanently covered by floating ice shelves [1], providing aphotic conditions [2, 3] for a depauperate fauna sustained by laterally advected food [4, 5]. In much of the remaining Antarctic shallows (<300 m depth), seasonal sea-ice melting allows a patchy primary production supporting rich ...
Santoro Stefano - - 2013
Agarsenone (1), a new cadinane sesquiterpenoid, was isolated from the resin of Commiphora erythraea. The structures of 1 and its decomposition products agarsenolides (2a and 2b) and myrrhone (3) were established by extensive NMR spectroscopic analysis. The absolute configuration of 3 and the relative and absolute configurations of 1 were ...
Savić Tatjana D - - 2013
The surface modification of nanocrystalline TiO2 particles (45 Å) with salicylate-type ligands consisting of an extended aromatic ring system, specifically 3-hydroxy-2-naphthoic acid, 3,5-dihydroxy-2-naphthoic acid and 3,7-dihydroxy-2-naphthoic acid, was found to alter the optical properties of nanoparticles in a similar way to salicylic acid. The formation of the inner-sphere charge-transfer (CT) ...
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