Institution
Hokkaido University
Education•Sapporo, Hokkaidô, Japan•
About: Hokkaido University is a education organization based out in Sapporo, Hokkaidô, Japan. It is known for research contribution in the topics: Population & Catalysis. The organization has 53925 authors who have published 115403 publications receiving 2651647 citations. The organization is also known as: Hokudai & Hokkaidō daigaku.
Topics: Population, Catalysis, Gene, Transplantation, Virus
Papers published on a yearly basis
Papers
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TL;DR: It is shown, by transmission electron microscopy of serially sectioned virions, that theRNPs of influenza A virus are organized in a distinct pattern (seven segments of different lengths surrounding a central segment), arguing against random incorporation of RNPs into virions and supporting instead a model in which each segment contains specific incorporation signals that enable the RNPs to be recruited and packaged as a complete set.
Abstract: In viruses, as in eukaryotes, elaborate mechanisms have evolved to protect the genome and to ensure its timely replication and reliable transmission to progeny. Influenza A viruses are enveloped, spherical or filamentous structures, ranging from 80 to 120 nm in diameter. Inside each envelope is a viral genome consisting of eight single-stranded negative-sense RNA segments of 890 to 2,341 nucleotides each. These segments are associated with nucleoprotein and three polymerase subunits, designated PA, PB1 and PB2; the resultant ribonucleoprotein complexes (RNPs) resemble a twisted rod (10-15 nm in width and 30-120 nm in length) that is folded back and coiled on itself. Late in viral infection, newly synthesized RNPs are transported from the nucleus to the plasma membrane, where they are incorporated into progeny virions capable of infecting other cells. Here we show, by transmission electron microscopy of serially sectioned virions, that the RNPs of influenza A virus are organized in a distinct pattern (seven segments of different lengths surrounding a central segment). The individual RNPs are suspended from the interior of the viral envelope at the distal end of the budding virion and are oriented perpendicular to the budding tip. This finding argues against random incorporation of RNPs into virions, supporting instead a model in which each segment contains specific incorporation signals that enable the RNPs to be recruited and packaged as a complete set. A selective mechanism of RNP incorporation into virions and the unique organization of the eight RNP segments may be crucial to maintaining the integrity of the viral genome during repeated cycles of replication.
428 citations
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TL;DR: The results of the present study suggest that the PYY-containing enteroendocrine cells and 5-HT-containing mucosal mast cells sense SCFAs via the GPR43 receptor, which is consistent with physiological data showing thatSCFAs stimulate the release of PYY and5-HT from the ileum and colon.
Abstract: Short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, are the major anions in the large intestinal lumen. They are produced from dietary fiber by bacterial fermentation and are known to have a variety of physiological and pathophysiological effects on the intestine. In the present study, we investigated the expression of the SCFA receptor, GPR43, in the rat distal ileum and colon. Expression of GPR43 was detected by reverse transcriptase/polymerase chain reaction (RT-PCR), Western blotting, and immunohistochemistry. mRNA for GPR43 was detected, by RT-PCR, in extracts of the whole wall and separated mucosa from the ileum and colon and from muscle plus submucosa from the ileum, but not from muscle plus submucosa preparations from the colon. We raised a rabbit antiserum against a synthesized fragment of rat GPR43; this was specific for rat GPR43. GPR43 protein was detected by Western blot analysis in extracts of whole wall and separated mucosa, but not in muscle plus submucosa extracts. By immunohistochemistry, GPR43 immunoreactivity was localized to enteroendocrine cells expressing peptide YY (PYY), whereas 5-hydroxytryptamine (5-HT)-immunoreactive (IR) enteroendocrine cells were not immunoreactive for GPR43. Mast cells of the lamina propria expressing 5-HT were also GPR43-IR. The results of the present study suggest that the PYY-containing enteroendocrine cells and 5-HT-containing mucosal mast cells sense SCFAs via the GPR43 receptor. This is consistent with physiological data showing that SCFAs stimulate the release of PYY and 5-HT from the ileum and colon.
426 citations
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National Center for Atmospheric Research1, Pusan National University2, Cornell University3, Geophysical Fluid Dynamics Laboratory4, University of Texas at Austin5, Lamont–Doherty Earth Observatory6, University of Paris7, University of Victoria8, Northwestern University9, University of Colorado Boulder10, Cooperative Institute for Research in Environmental Sciences11, ETH Zurich12, Institute of Arctic and Alpine Research13, Max Planck Society14, University of California, Los Angeles15, Hokkaido University16, University of California, Irvine17, University of Exeter18
TL;DR: In this article, a collection of initial-condition large ensembles (LEs) generated with seven Earth system models under historical and future radiative forcing scenarios provides new insights into uncertainties due to internal variability versus model differences.
Abstract: Internal variability in the climate system confounds assessment of human-induced climate change and imposes irreducible limits on the accuracy of climate change projections, especially at regional and decadal scales. A new collection of initial-condition large ensembles (LEs) generated with seven Earth system models under historical and future radiative forcing scenarios provides new insights into uncertainties due to internal variability versus model differences. These data enhance the assessment of climate change risks, including extreme events, and offer a powerful testbed for new methodologies aimed at separating forced signals from internal variability in the observational record. Opportunities and challenges confronting the design and dissemination of future LEs, including increased spatial resolution and model complexity alongside emerging Earth system applications, are discussed. Climate change detection is confounded by internal variability, but recent initial-condition large ensembles (LEs) have begun addressing this issue. This Perspective discusses the value of multi-model LEs, the challenges of providing them and their role in future climate change research.
426 citations
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University of Leeds1, James Cook University2, University College London3, Ulster University4, Universiti Brunei Darussalam5, Forestry Commission6, New York Botanical Garden7, Museu Paraense Emílio Goeldi8, University of Exeter9, Universidad Autónoma Gabriel René Moreno10, Wageningen University and Research Centre11, University of Amsterdam12, University of Edinburgh13, Universidad Nacional de la Amazonía Peruana14, Paul Sabatier University15, National Park Service16, University of Texas at Austin17, Forestry Research Institute of Ghana18, University of São Paulo19, Smithsonian Institution20, Hokkaido University21, National University of Colombia22, Forest Research Institute Malaysia23, Conservation International24, University of Twente25, Environmental Change Institute26, Universidade do Estado de Mato Grosso27, University of York28, Commonwealth Scientific and Industrial Research Organisation29, University of Cambridge30, Duke University31, University of Los Andes32, Karlsruhe Institute of Technology33, Universidade Federal do Acre34, University of Yaoundé I35, Naturalis36, University of Wisconsin–Milwaukee37, Smithsonian Tropical Research Institute38, University of Stirling39
TL;DR: In this article, the effect of tree height (H) on tropical forest biomass and carbon storage estimates was investigated using data from 20 sites across four continents, and the results showed that tree H is an important allometric factor that needs to be included in future forest biomass estimates to reduce error in estimates of tropical carbon stocks and emissions.
Abstract: . Aboveground tropical tree biomass and carbon storage estimates commonly ignore tree height (H). We estimate the effect of incorporating H on tropics-wide forest biomass estimates in 327 plots across four continents using 42 656 H and diameter measurements and harvested trees from 20 sites to answer the following questions: 1. What is the best H-model form and geographic unit to include in biomass models to minimise site-level uncertainty in estimates of destructive biomass? 2. To what extent does including H estimates derived in (1) reduce uncertainty in biomass estimates across all 327 plots? 3. What effect does accounting for H have on plot- and continental-scale forest biomass estimates? The mean relative error in biomass estimates of destructively harvested trees when including H (mean 0.06), was half that when excluding H (mean 0.13). Power- and Weibull-H models provided the greatest reduction in uncertainty, with regional Weibull-H models preferred because they reduce uncertainty in smaller-diameter classes (≤40 cm D) that store about one-third of biomass per hectare in most forests. Propagating the relationships from destructively harvested tree biomass to each of the 327 plots from across the tropics shows that including H reduces errors from 41.8 Mg ha−1 (range 6.6 to 112.4) to 8.0 Mg ha−1 (−2.5 to 23.0). For all plots, aboveground live biomass was −52.2 Mg ha−1 (−82.0 to −20.3 bootstrapped 95% CI), or 13%, lower when including H estimates, with the greatest relative reductions in estimated biomass in forests of the Brazilian Shield, east Africa, and Australia, and relatively little change in the Guiana Shield, central Africa and southeast Asia. Appreciably different stand structure was observed among regions across the tropical continents, with some storing significantly more biomass in small diameter stems, which affects selection of the best height models to reduce uncertainty and biomass reductions due to H. After accounting for variation in H, total biomass per hectare is greatest in Australia, the Guiana Shield, Asia, central and east Africa, and lowest in east-central Amazonia, W. Africa, W. Amazonia, and the Brazilian Shield (descending order). Thus, if tropical forests span 1668 million km2 and store 285 Pg C (estimate including H), then applying our regional relationships implies that carbon storage is overestimated by 35 Pg C (31–39 bootstrapped 95% CI) if H is ignored, assuming that the sampled plots are an unbiased statistical representation of all tropical forest in terms of biomass and height factors. Our results show that tree H is an important allometric factor that needs to be included in future forest biomass estimates to reduce error in estimates of tropical carbon stocks and emissions due to deforestation.
426 citations
Authors
Showing all 54156 results
Name | H-index | Papers | Citations |
---|---|---|---|
Shizuo Akira | 261 | 1308 | 320561 |
Yi Cui | 220 | 1015 | 199725 |
John F. Hartwig | 145 | 714 | 66472 |
Yoshihiro Kawaoka | 139 | 883 | 75087 |
David Y. Graham | 138 | 1047 | 80886 |
Takashi Kadowaki | 137 | 873 | 89729 |
Kazunari Domen | 130 | 908 | 77964 |
Susumu Kitagawa | 125 | 809 | 69594 |
Toshikazu Nakamura | 121 | 732 | 51374 |
Toshio Hirano | 120 | 401 | 55721 |
Li-Jun Wan | 113 | 639 | 52128 |
Wenbin Lin | 113 | 474 | 56786 |
Xiaoming Li | 113 | 1932 | 72445 |
Jinhua Ye | 112 | 658 | 49496 |
Terence Tao | 111 | 606 | 94316 |