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  • Oxford University Press  (483)
  • American Geophysical Union (AGU)
  • Blackwell Publishing Ltd
  • Nature Publishing Group
  • 2015-2019  (246)
  • 2010-2014  (243)
  • 1945-1949  (9)
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  • 11
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 160 (1947), S. 900-901 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SINCE starch can be split into maltose, the opinion has been widespread that starch is composed of chains of the maltose type1. Some authors, however, suggested a branched or netted structure2,3; comparative measurements of molecular weight and viscosity were ...
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  • 12
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 160 (1947), S. 155-156 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] IN previous experiments a method was found for the cultivation of the exoerythrocytic form of Plasmodium gallinaceum in tissue cultures of embryonic chicken brain. It was found that proliferation of the parasites in tissue culture cells is very slow, and that the initial stages are difficult to ...
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  • 13
    Publication Date: 2015-08-15
    Description: We use a new, improved version of the H i Parkes All-Sky Survey to search for H i emission from nine new, ultrafaint Milky Way satellite galaxy candidates recently discovered in data from the Dark Energy Survey. None of the candidates is detected in H i , implying upper limits for their H i masses of typically several hundred to a few thousand solar masses. The resulting upper limits on $M_{\rm H\small {I}} / L_{\rm V}$ and $M_{\rm H\small {I}} / M_{\star }$ suggest that at least some of the new galaxy candidates are H i deficient. This finding is consistent with the general H i deficiency of satellite galaxies located within the Milky Way's virial radius and supports the hypothesis that gas is being removed from satellites by tidal and ram-pressure forces during perigalactic passages. In addition, some of the objects may be embedded in, and interacting with, the extended neutral and ionized gas filaments of the Magellanic Stream.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 14
    Publication Date: 2015-09-11
    Description: We examine the properties of galaxies in the Galaxies and Mass Assembly (GAMA) survey located in voids with radii 〉10 h –1  Mpc. Utilizing the GAMA equatorial survey, 592 void galaxies are identified out to z   0.1 brighter than M r  = –18.4, our magnitude completeness limit. Using the W Hα versus [N  ii ]/Hα (WHAN) line strength diagnostic diagram, we classify their spectra as star forming, AGN, or dominated by old stellar populations. For objects more massive than 5  x  10 9 M , we identify a sample of 26 void galaxies with old stellar populations classed as passive and retired galaxies in the WHAN diagnostic diagram, else they lack any emission lines in their spectra. When matched to Wide-field Infrared Survey Explorer mid-IR photometry, these passive and retired galaxies exhibit a range of mid-IR colour, with a number of void galaxies exhibiting [4.6] – [12] colours inconsistent with completely quenched stellar populations, with a similar spread in colour seen for a randomly drawn non-void comparison sample. We hypothesize that a number of these galaxies host obscured star formation, else they are star forming outside of their central regions targeted for single-fibre spectroscopy. When matched to a randomly drawn sample of non-void galaxies, the void and non-void galaxies exhibit similar properties in terms of optical and mid-IR colour, morphology, and star formation activity, suggesting comparable mass assembly and quenching histories. A trend in mid-IR [4.6] – [12] colour is seen, such that both void and non-void galaxies with quenched/passive colours 〈1.5 typically have masses higher than 10 10 M , where internally driven processes play an increasingly important role in galaxy evolution.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 15
    Publication Date: 2015-09-27
    Description: We report the discovery of a low-mass companion to the nearby ( d = 47 pc) F7V star HD 984. The companion is detected 0.19 arcsec away from its host star in the L ' band with the Apodized Phase Plate on NaCo/Very Large Telescope and was recovered by L '-band non-coronagraphic imaging data taken a few days later. We confirm the companion is comoving with the star with SINFONI integral field spectrograph H + K data. We present the first published data obtained with SINFONI in pupil-tracking mode. HD 984 has been argued to be a kinematic member of the 30 Myr-old Columba group, and its HR diagram position is not altogether inconsistent with being a zero-age main sequence star of this age. By consolidating different age indicators, including isochronal age, coronal X-ray emission, and stellar rotation, we independently estimate a main-sequence age of 115 ± 85 Myr (95 per cent CL) which does not rely on this kinematic association. The mass of directly imaged companions are usually inferred from theoretical evolutionary tracks, which are highly dependent on the age of the star. Based on the age extrema, we demonstrate that with our photometric data alone, the companion's mass is highly uncertain: between 33 and 96 M Jup (0.03–0.09 M ) using the COND evolutionary models. We compare the companion's SINFONI spectrum with field dwarf spectra to break this degeneracy. Based on the slope and shape of the spectrum in the H band, we conclude that the companion is an M6.0 ± 0.5 dwarf. The age of the system is not further constrained by the companion, as M dwarfs are poorly fit on low-mass evolutionary tracks. This discovery emphasizes the importance of obtaining a spectrum to spectral type companions around F-stars.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 16
    Publication Date: 2015-09-27
    Description: We report the results of a direct imaging survey of A- and F-type main-sequence stars searching for giant planets. A/F stars are often the targets of surveys, as they are thought to have more massive giant planets relative to solar-type stars. However, most imaging is only sensitive to orbital separations 〉30 au, where it has been demonstrated that giant planets are rare. In this survey, we take advantage of the high-contrast capabilities of the Apodizing Phase Plate coronagraph on NACO at the Very Large Telescope. Combined with optimized principal component analysis post-processing, we are sensitive to planetary-mass companions (2–12 M Jup ) at Solar system scales (≤30 au). We obtained data on 13 stars in the L ' band and detected one new companion as part of this survey: an M6.0 ± 0.5 dwarf companion around HD 984. We re-detect low-mass companions around HD 12894 and HD 20385, both reported shortly after the completion of this survey. We use Monte Carlo simulations to determine new constraints on the low-mass (〈80 M Jup ) companion frequency, as a function of mass and separation. Assuming solar-type planet mass and separation distributions, normalized to the planet frequency appropriate for A-stars, and the observed companion mass-ratio distribution for stellar companions extrapolated to planetary masses, we derive a truncation radius for the planetary mass companion surface density of 〈135 au at 95 per cent confidence.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 17
    Publication Date: 2015-11-22
    Description: Gene regulatory networks (GRN) are central to developmental processes. They are composed of transcription factors and signaling molecules orchestrating gene expression modules that tightly regulate the development of organisms. The neural crest (NC) is a multipotent cell population that is considered a key innovation of vertebrates. Its derivatives contribute to shaping the astounding morphological diversity of jaws, teeth, head skeleton, or pigmentation. Here, we study the molecular evolution of the NC GRN by analyzing patterns of molecular divergence for a total of 36 genes in 16 species of bony fishes. Analyses of nonsynonymous to synonymous substitution rate ratios (d N /d S ) support patterns of variable selective pressures among genes deployed at different stages of NC development, consistent with the developmental hourglass model. Model-based clustering techniques of sequence features support the notion of extreme conservation of NC-genes across the entire network. Our data show that most genes are under strong purifying selection that is maintained throughout ray-finned fish evolution. Late NC development genes reveal a pattern of increased constraints in more recent lineages. Additionally, seven of the NC-genes showed signs of relaxation of purifying selection in the famously species-rich lineage of cichlid fishes. This suggests that NC genes might have played a role in the adaptive radiation of cichlids by granting flexibility in the development of NC-derived traits—suggesting an important role for NC network architecture during the diversification in vertebrates.
    Electronic ISSN: 1759-6653
    Topics: Biology
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  • 18
    Publication Date: 2015-08-29
    Description: On average, mutations are deleterious to proteins. Mutations conferring new function to a protein often come at the expense of protein folding or stability, reducing overall activity. Over the years, a panel of T7 RNA polymerases have been designed or evolved to accept nucleotides with modified ribose moieties. These modified RNAs have proven useful, especially in vivo , but the transcriptional yields tend to be quite low. Here we show that mutations previously shown to increase the thermal tolerance of T7 RNA polymerase can increase the activity of mutants with expanded substrate range. The resulting polymerase mutants can be used to generate 2' -O- methyl modified RNA with yields much higher than enzymes currently employed.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
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  • 19
    Publication Date: 2016-07-14
    Description: Beetles represent the largest insect order and they display extreme morphological, ecological and behavioral diversity, which makes them ideal models for evolutionary studies. Here, we present the draft genome of the scarab beetle Oryctes borbonicus , which has a more basal phylogenetic position than the two previously sequenced pest species Tribolium castaneum and Dendroctonus ponderosae providing the potential for sequence polarization. Oryctes borbonicus is endemic to La Réunion, an island located in the Indian Ocean, and is the host of the nematode Pristionchus pacificus , a well-established model organism for integrative evolutionary biology. At 518 Mb, the O. borbonicus genome is substantially larger and encodes more genes than T. castaneum and D. ponderosae . We found that only 25% of the predicted genes of O. borbonicus are conserved as single copy genes across the nine investigated insect genomes, suggesting substantial gene turnover within insects. Even within beetles, up to 21% of genes are restricted to only one species, whereas most other genes have undergone lineage-specific duplications and losses. We illustrate lineage-specific duplications using detailed phylogenetic analysis of two gene families. This study serves as a reference point for insect/coleopteran genomics, although its original motivation was to find evidence for potential horizontal gene transfer (HGT) between O. borbonicus and P. pacificus . The latter was previously shown to be the recipient of multiple horizontally transferred genes including some genes from insect donors. However, our study failed to provide any clear evidence for additional HGTs between the two species.
    Electronic ISSN: 1759-6653
    Topics: Biology
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  • 20
    Publication Date: 2013-06-06
    Description: : INstruct is a database of high-quality, 3D, structurally resolved protein interactome networks in human and six model organisms. INstruct combines the scale of available high-quality binary protein interaction data with the specificity of atomic-resolution structural information derived from co-crystal evidence using a tested interaction interface inference method. Its web interface is designed to allow for flexible search based on standard and organism-specific protein and gene-naming conventions, visualization of protein architecture highlighting interaction interfaces and viewing and downloading custom 3D structurally resolved interactome datasets. Availability: INstruct is freely available on the web at http://instruct.yulab.org with all major browsers supported. Contact: haiyuan.yu@cornell.edu Supplementary information: Supplementary data are available at Bioinformatics online.
    Print ISSN: 1367-4803
    Electronic ISSN: 1460-2059
    Topics: Biology , Computer Science , Medicine
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