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  • Articles  (391)
  • Models, Biological  (391)
  • 2005-2009  (391)
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  • Articles  (391)
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  • 1
    Publication Date: 2009-12-23
    Description: Reprogramming of somatic cell nuclei to yield induced pluripotent stem (iPS) cells makes possible derivation of patient-specific stem cells for regenerative medicine. However, iPS cell generation is asynchronous and slow (2-3 weeks), the frequency is low (〈0.1%), and DNA demethylation constitutes a bottleneck. To determine regulatory mechanisms involved in reprogramming, we generated interspecies heterokaryons (fused mouse embryonic stem (ES) cells and human fibroblasts) that induce reprogramming synchronously, frequently and fast. Here we show that reprogramming towards pluripotency in single heterokaryons is initiated without cell division or DNA replication, rapidly (1 day) and efficiently (70%). Short interfering RNA (siRNA)-mediated knockdown showed that activation-induced cytidine deaminase (AID, also known as AICDA) is required for promoter demethylation and induction of OCT4 (also known as POU5F1) and NANOG gene expression. AID protein bound silent methylated OCT4 and NANOG promoters in fibroblasts, but not active demethylated promoters in ES cells. These data provide new evidence that mammalian AID is required for active DNA demethylation and initiation of nuclear reprogramming towards pluripotency in human somatic cells.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2906123/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2906123/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bhutani, Nidhi -- Brady, Jennifer J -- Damian, Mara -- Sacco, Alessandra -- Corbel, Stephane Y -- Blau, Helen M -- AG009521/AG/NIA NIH HHS/ -- AG024987/AG/NIA NIH HHS/ -- AI007328/AI/NIAID NIH HHS/ -- R01 AG009521/AG/NIA NIH HHS/ -- R01 AG009521-25/AG/NIA NIH HHS/ -- R01 AG024987/AG/NIA NIH HHS/ -- R01 AG024987-05/AG/NIA NIH HHS/ -- T32 AI007328/AI/NIAID NIH HHS/ -- U01 HL100397/HL/NHLBI NIH HHS/ -- England -- Nature. 2010 Feb 25;463(7284):1042-7. doi: 10.1038/nature08752.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Baxter Laboratory for Stem Cell Biology, Institute for Stem Cell Biology and Regenerative Medicine, Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California 94305-5175, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20027182" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Division ; Cell Fusion ; Cell Line ; Cells, Cultured ; Cellular Reprogramming/genetics/*physiology ; Chromatin Immunoprecipitation ; Cytidine Deaminase/deficiency/genetics/*metabolism ; DNA/chemistry/genetics/metabolism ; *DNA Methylation ; DNA Replication ; Embryonic Stem Cells/cytology/metabolism ; Fibroblasts/cytology/metabolism ; Gene Expression Regulation ; Gene Knockdown Techniques ; Homeodomain Proteins/genetics ; Humans ; Induced Pluripotent Stem Cells/*cytology/enzymology/*metabolism ; Lung/cytology/embryology ; Mice ; Models, Biological ; Octamer Transcription Factor-3/genetics ; Promoter Regions, Genetic/genetics ; Time Factors
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  • 2
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    Nature Publishing Group (NPG)
    Publication Date: 2008-11-21
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉England -- Nature. 2008 Nov 20;456(7220):317-8. doi: 10.1038/456317a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19020598" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Anniversaries and Special Events ; Biodiversity ; *Biological Evolution ; Epidemiology/trends ; Humans ; Models, Biological ; Mutagenesis ; Religion and Science ; Science/*trends ; Selection, Genetic
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  • 3
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    Nature Publishing Group (NPG)
    Publication Date: 2008-06-20
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Luo, Ji -- Elledge, Stephen J -- England -- Nature. 2008 Jun 19;453(7198):995-6. doi: 10.1038/453995a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18563141" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Transformation, Neoplastic/*genetics ; Colonic Neoplasms/genetics/pathology ; Gene Expression Regulation, Neoplastic ; Genes, p53/genetics ; Genes, ras/genetics ; Humans ; Models, Biological ; Oncogenes/*genetics
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  • 4
    Publication Date: 2008-08-30
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ingolia, Nicholas T -- Weissman, Jonathan S -- England -- Nature. 2008 Aug 28;454(7208):1059-62. doi: 10.1038/4541059a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18756243" target="_blank"〉PubMed〈/a〉
    Keywords: *Environment ; Galactose/metabolism ; *Gene Expression Regulation, Fungal/drug effects ; Glucose/metabolism/pharmacology ; Metabolic Networks and Pathways/drug effects/*genetics ; Microfluidics ; Models, Biological ; Osmotic Pressure ; RNA Stability/drug effects ; Saccharomyces cerevisiae/classification/drug effects/*genetics/*metabolism ; Systems Biology
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  • 5
    Publication Date: 2008-02-26
    Description: Maintaining cell shape and tone is crucial for the function and survival of cells and tissues. Mechanotransduction relies on the transformation of minuscule mechanical forces into high-fidelity electrical responses. When mechanoreceptors are stimulated, mechanically sensitive cation channels open and produce an inward transduction current that depolarizes the cell. For this process to operate effectively, the transduction machinery has to retain integrity and remain unfailingly independent of environmental changes. This is particularly challenging for poikilothermic organisms, where changes in temperature in the environment may impact the function of mechanoreceptor neurons. Thus, we wondered how insects whose habitat might quickly vary over several tens of degrees of temperature manage to maintain highly effective mechanical senses. We screened for Drosophila mutants with defective mechanical responses at elevated ambient temperatures, and identified a gene, spam, whose role is to protect the mechanosensory organ from massive cellular deformation caused by heat-induced osmotic imbalance. Here we show that Spam protein forms an extracellular shield that guards mechanosensory neurons from environmental insult. Remarkably, heterologously expressed Spam protein also endowed other cells with superb defence against physically and chemically induced deformation. We studied the mechanical impact of Spam coating and show that spam-coated cells are up to ten times stiffer than uncoated controls. Together, these results help explain how poikilothermic organisms preserve the architecture of critical cells during environmental stress, and illustrate an elegant and simple solution to such challenge.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2387185/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2387185/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cook, Boaz -- Hardy, Robert W -- McConnaughey, William B -- Zuker, Charles S -- R01 EY006979/EY/NEI NIH HHS/ -- R01 EY006979-18/EY/NEI NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2008 Mar 20;452(7185):361-4. doi: 10.1038/nature06603. Epub 2008 Feb 24.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute and Departments of Neurobiology and Neurosciences, University of California at San Diego, La Jolla, California 92093-0649, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18297055" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Line ; Cell Shape/*drug effects/*physiology ; Drosophila Proteins/genetics/metabolism ; Drosophila melanogaster/*cytology/drug effects/genetics/physiology ; Electrophysiology ; *Environment ; Eye Proteins/genetics/metabolism ; Hot Temperature ; Humidity ; Mechanoreceptors/cytology/physiology ; Mechanotransduction, Cellular/*drug effects/*physiology ; Models, Biological ; Osmotic Pressure ; Stimulation, Chemical ; Stress, Mechanical
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  • 6
    Publication Date: 2008-03-07
    Description: Complex dynamics are often shown by simple ecological models and have been clearly demonstrated in laboratory and natural systems. Yet many classes of theoretically possible dynamics are still poorly documented in nature. Here we study long-term time-series data of a midge, Tanytarsus gracilentus (Diptera: Chironomidae), in Lake Myvatn, Iceland. The midge undergoes density fluctuations of almost six orders of magnitude. Rather than regular cycles, however, these fluctuations have irregular periods of 4-7 years, indicating complex dynamics. We fit three consumer-resource models capable of qualitatively distinct dynamics to the data. Of these, the best-fitting model shows alternative dynamical states in the absence of environmental variability; depending on the initial midge densities, the model shows either fluctuations around a fixed point or high-amplitude cycles. This explains the observed complex population dynamics: high-amplitude but irregular fluctuations occur because stochastic variability causes the dynamics to switch between domains of attraction to the alternative states. In the model, the amplitude of fluctuations depends strongly on minute resource subsidies into the midge habitat. These resource subsidies may be sensitive to human-caused changes in the hydrology of the lake, with human impacts such as dredging leading to higher-amplitude fluctuations. Tanytarsus gracilentus is a key component of the Myvatn ecosystem, representing two-thirds of the secondary productivity of the lake and providing vital food resources to fish and to breeding bird populations. Therefore the high-amplitude, irregular fluctuations in midge densities generated by alternative dynamical states dominate much of the ecology of the lake.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ives, Anthony R -- Einarsson, Arni -- Jansen, Vincent A A -- Gardarsson, Arnthor -- England -- Nature. 2008 Mar 6;452(7183):84-7. doi: 10.1038/nature06610.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Zoology, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA. arives@wisc.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18322533" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Chironomidae/*physiology ; Computer Simulation ; *Ecosystem ; Eukaryota/physiology ; Food ; *Fresh Water ; Iceland ; Models, Biological ; Population Density ; Stochastic Processes
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  • 7
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    Nature Publishing Group (NPG)
    Publication Date: 2008-06-06
    Description: 〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2865228/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2865228/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Warburton, David -- P01 HL060231/HL/NHLBI NIH HHS/ -- P01 HL060231-09/HL/NHLBI NIH HHS/ -- R01 HL044060/HL/NHLBI NIH HHS/ -- R01 HL044977/HL/NHLBI NIH HHS/ -- R01 HL044977-16/HL/NHLBI NIH HHS/ -- England -- Nature. 2008 Jun 5;453(7196):733-5. doi: 10.1038/453733a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18528385" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptor Proteins, Signal Transducing ; Animals ; Body Patterning/genetics/*physiology ; Fibroblast Growth Factor 10/metabolism ; Intracellular Signaling Peptides and Proteins ; Lung/*anatomy & histology/*embryology/metabolism ; Membrane Proteins/metabolism ; Mice ; Models, Biological ; Organogenesis/genetics/*physiology ; Receptor, Fibroblast Growth Factor, Type 2/genetics/metabolism
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  • 8
    Publication Date: 2008-04-11
    Description: There exists controversy over the nature of haematopoietic progenitors of T cells. Most T cells develop in the thymus, but the lineage potential of thymus-colonizing progenitors is unknown. One approach to resolving this question is to determine the lineage potentials of the earliest thymic progenitors (ETPs). Previous work has shown that ETPs possess T and natural killer lymphoid potentials, and rare subsets of ETPs also possess B lymphoid potential, suggesting an origin from lymphoid-restricted progenitor cells. However, whether ETPs also possess myeloid potential is unknown. Here we show that nearly all ETPs in adult mice possess both T and myeloid potential in clonal assays. The existence of progenitors possessing T and myeloid potential within the thymus is incompatible with the current dominant model of haematopoiesis, in which T cells are proposed to arise from lymphoid-. Our results indicate that alternative models for lineage commitment during haematopoiesis must be considered.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bell, J Jeremiah -- Bhandoola, Avinash -- England -- Nature. 2008 Apr 10;452(7188):764-7. doi: 10.1038/nature06840.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18401411" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Cell Lineage ; Cells, Cultured ; Coculture Techniques ; Dendritic Cells/cytology ; Female ; Granulocytes/cytology ; *Hematopoiesis ; Hematopoietic Stem Cells/*cytology/metabolism ; Macrophages/cytology ; Mice ; Models, Biological ; Myeloid Cells/*cytology/metabolism ; Stromal Cells/cytology ; T-Lymphocytes/*cytology/metabolism ; Thymus Gland/*cytology
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  • 9
    Publication Date: 2008-10-03
    Description: The integrity of the cornea, the most anterior part of the eye, is indispensable for vision. Forty-five million individuals worldwide are bilaterally blind and another 135 million have severely impaired vision in both eyes because of loss of corneal transparency; treatments range from local medications to corneal transplants, and more recently to stem cell therapy. The corneal epithelium is a squamous epithelium that is constantly renewing, with a vertical turnover of 7 to 14 days in many mammals. Identification of slow cycling cells (label-retaining cells) in the limbus of the mouse has led to the notion that the limbus is the niche for the stem cells responsible for the long-term renewal of the cornea; hence, the corneal epithelium is supposedly renewed by cells generated at and migrating from the limbus, in marked opposition to other squamous epithelia in which each resident stem cell has in charge a limited area of epithelium. Here we show that the corneal epithelium of the mouse can be serially transplanted, is self-maintained and contains oligopotent stem cells with the capacity to generate goblet cells if provided with a conjunctival environment. Furthermore, the entire ocular surface of the pig, including the cornea, contains oligopotent stem cells (holoclones) with the capacity to generate individual colonies of corneal and conjunctival cells. Therefore, the limbus is not the only niche for corneal stem cells and corneal renewal is not different from other squamous epithelia. We propose a model that unifies our observations with the literature and explains why the limbal region is enriched in stem cells.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Majo, Francois -- Rochat, Ariane -- Nicolas, Michael -- Jaoude, Georges Abou -- Barrandon, Yann -- England -- Nature. 2008 Nov 13;456(7219):250-4. doi: 10.1038/nature07406. Epub 2008 Oct 1.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Stem Cell Dynamics, Ecole Polytechnique Federale de Lausanne (EPFL), 1015 Lausanne CH, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18830243" target="_blank"〉PubMed〈/a〉
    Keywords: Adult Stem Cells/*cytology ; Animals ; Cattle ; Cells, Cultured ; Child, Preschool ; Clone Cells ; Corneal Transplantation ; Epithelium, Corneal/*cytology/metabolism ; Female ; Gene Expression Regulation ; Humans ; Infant ; Keratinocytes/cytology/metabolism ; Male ; Mice ; Mice, SCID ; Models, Biological ; Multipotent Stem Cells/*cytology ; Proteins/metabolism ; Rats ; Swine
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  • 10
    Publication Date: 2008-01-22
    Description: Understanding the mechanisms that determine an individual's sex remains a primary challenge for evolutionary biology. Chromosome-based systems (genotypic sex determination) that generate roughly equal numbers of sons and daughters accord with theory, but the adaptive significance of environmental sex determination (that is, when embryonic environmental conditions determine offspring sex, ESD) is a major unsolved problem. Theoretical models predict that selection should favour ESD over genotypic sex determination when the developmental environment differentially influences male versus female fitness (that is, the Charnov-Bull model), but empirical evidence for this hypothesis remains elusive in amniote vertebrates--the clade in which ESD is most prevalent. Here we provide the first substantial empirical support for this model by showing that incubation temperatures influence reproductive success of males differently than that of females in a short-lived lizard (Amphibolurus muricatus, Agamidae) with temperature-dependent sex determination. We incubated eggs at a variety of temperatures, and de-confounded sex and incubation temperature by using hormonal manipulations to embryos. We then raised lizards in field enclosures and quantified their lifetime reproductive success. Incubation temperature affected reproductive success differently in males versus females in exactly the way predicted by theory: the fitness of each sex was maximized by the incubation temperature that produces that sex. Our results provide unequivocal empirical support for the Charnov-Bull model for the adaptive significance of temperature-dependent sex determination in amniote vertebrates.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Warner, D A -- Shine, R -- England -- Nature. 2008 Jan 31;451(7178):566-8. doi: 10.1038/nature06519. Epub 2008 Jan 20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Biological Sciences, University of Sydney, Sydney, New South Wales 2006, Australia. dwarner@iastate.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18204437" target="_blank"〉PubMed〈/a〉
    Keywords: Acclimatization/physiology ; Adaptation, Physiological/*physiology ; Animals ; Body Size ; Fadrozole/pharmacology ; Female ; Lizards/*embryology/*physiology ; Male ; Models, Biological ; Ovum/drug effects/growth & development ; Reproduction/physiology ; Sex Characteristics ; Sex Differentiation/*physiology ; *Temperature
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  • 11
    Publication Date: 2008-02-15
    Description: Mathematical models predict that species interactions such as competition and predation can generate chaos. However, experimental demonstrations of chaos in ecology are scarce, and have been limited to simple laboratory systems with a short duration and artificial species combinations. Here, we present the first experimental demonstration of chaos in a long-term experiment with a complex food web. Our food web was isolated from the Baltic Sea, and consisted of bacteria, several phytoplankton species, herbivorous and predatory zooplankton species, and detritivores. The food web was cultured in a laboratory mesocosm, and sampled twice a week for more than 2,300 days. Despite constant external conditions, the species abundances showed striking fluctuations over several orders of magnitude. These fluctuations displayed a variety of different periodicities, which could be attributed to different species interactions in the food web. The population dynamics were characterized by positive Lyapunov exponents of similar magnitude for each species. Predictability was limited to a time horizon of 15-30 days, only slightly longer than the local weather forecast. Hence, our results demonstrate that species interactions in food webs can generate chaos. This implies that stability is not required for the persistence of complex food webs, and that the long-term prediction of species abundances can be fundamentally impossible.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Beninca, Elisa -- Huisman, Jef -- Heerkloss, Reinhard -- Johnk, Klaus D -- Branco, Pedro -- Van Nes, Egbert H -- Scheffer, Marten -- Ellner, Stephen P -- England -- Nature. 2008 Feb 14;451(7180):822-5. doi: 10.1038/nature06512.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Nieuwe Achtergracht 127, 1018 WS Amsterdam, The Netherlands.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18273017" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Bacteria/metabolism ; *Food Chain ; Models, Biological ; *Nonlinear Dynamics ; Oceans and Seas ; Plankton/*metabolism ; Population Dynamics ; Species Specificity ; Time Factors
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  • 12
    Publication Date: 2008-06-27
    Description: In groundbreaking experiments, Hans Spemann demonstrated that the dorsal part of the amphibian embryo can generate a well-proportioned tadpole, and that a small group of dorsal cells, the 'organizer', can induce a complete and well-proportioned twinned axis when transplanted into a host embryo. Key to organizer function is the localized secretion of inhibitors of bone morphogenetic protein (BMP), which defines a graded BMP activation profile. Although the central proteins involved in shaping this gradient are well characterized, their integrated function, and in particular how pattern scales with size, is not understood. Here we present evidence that in Xenopus, the BMP activity gradient is defined by a 'shuttling-based' mechanism, whereby the BMP ligands are translocated ventrally through their association with the BMP inhibitor Chordin. This shuttling, with feedback repression of the BMP ligand Admp, offers a quantitative explanation to Spemann's observations, and accounts naturally for the scaling of embryo pattern with its size.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ben-Zvi, Danny -- Shilo, Ben-Zion -- Fainsod, Abraham -- Barkai, Naama -- England -- Nature. 2008 Jun 26;453(7199):1205-11. doi: 10.1038/nature07059.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18580943" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Body Patterning ; Body Size ; Bone Morphogenetic Protein 4 ; Bone Morphogenetic Proteins/antagonists & inhibitors/*metabolism ; Embryo, Nonmammalian/embryology/*metabolism ; Glycoproteins/metabolism ; Intercellular Signaling Peptides and Proteins/metabolism ; Ligands ; Models, Biological ; Protein Transport ; Xenopus/*embryology/genetics/metabolism ; Xenopus Proteins/metabolism
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  • 13
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    Nature Publishing Group (NPG)
    Publication Date: 2008-05-30
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mandavilli, Apoorva -- England -- Nature. 2008 May 29;453(7195):581-2. doi: 10.1038/453581a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18509413" target="_blank"〉PubMed〈/a〉
    Keywords: Adult ; Defensins/metabolism ; *Ecosystem ; Feces/*microbiology ; Female ; Humans ; Infant, Newborn ; Intestines/*microbiology/*transplantation ; Models, Biological ; Nod2 Signaling Adaptor Protein/genetics/metabolism
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  • 14
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    Nature Publishing Group (NPG)
    Publication Date: 2008-02-14
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Speakman, John -- England -- Nature. 2008 Feb 14;451(7180):774-5. doi: 10.1038/451774a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18270540" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; Chiroptera/anatomy & histology/*physiology ; Cochlea/anatomy & histology/physiology ; Darkness ; Echolocation/*physiology ; Extremities/anatomy & histology/physiology ; Flight, Animal/*physiology ; Fossils ; Models, Biological ; Time Factors ; Wyoming
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  • 15
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    Nature Publishing Group (NPG)
    Publication Date: 2008-02-01
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Jones, Dan -- England -- Nature. 2008 Jan 31;451(7178):512-5. doi: 10.1038/451512a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18235473" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptation, Physiological ; Aggression/*physiology/psychology ; Altruism ; Anger/physiology ; Animals ; Antisocial Personality Disorder/physiopathology ; *Biological Evolution ; Conflict (Psychology) ; Female ; History, 15th Century ; History, 16th Century ; History, 17th Century ; History, 18th Century ; History, 19th Century ; History, 20th Century ; History, 21st Century ; History, Medieval ; *Homicide/history/psychology ; Humans ; Male ; Models, Biological ; Morals ; Pan troglodytes/physiology ; Prefrontal Cortex/anatomy & histology/physiology ; Sex Characteristics ; United Nations ; Violence/psychology ; Warfare
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  • 16
    Publication Date: 2008-02-01
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Crews, David -- Bull, James J -- England -- Nature. 2008 Jan 31;451(7178):527-8. doi: 10.1038/451527a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18235487" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptation, Physiological/*physiology ; Animals ; Body Size ; Fadrozole/pharmacology ; Female ; Lizards/*embryology/*physiology ; Male ; Models, Biological ; Ovum/drug effects/growth & development ; Reproduction/physiology ; Sex Characteristics ; Sex Differentiation/*physiology ; *Temperature
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  • 17
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    Nature Publishing Group (NPG)
    Publication Date: 2008-09-19
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Marris, Emma -- England -- Nature. 2008 Sep 18;455(7211):277-80. doi: 10.1038/455277a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18800107" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Conservation of Natural Resources/methods ; *Ecosystem ; Human Activities ; Models, Biological ; Nature ; Poland ; Time Factors ; *Trees/physiology
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  • 18
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    Nature Publishing Group (NPG)
    Publication Date: 2008-05-24
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Marris, Emma -- England -- Nature. 2008 May 22;453(7194):446-8. doi: 10.1038/453446a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18497792" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; Computer Simulation ; Humans ; *Language ; *Linguistics ; Models, Biological
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  • 19
    Publication Date: 2008-02-22
    Description: Messenger-RNA-directed protein synthesis is accomplished by the ribosome. In eubacteria, this complex process is initiated by a specialized transfer RNA charged with formylmethionine (tRNA(fMet)). The amino-terminal formylated methionine of all bacterial nascent polypeptides blocks the reactive amino group to prevent unfavourable side-reactions and to enhance the efficiency of translation initiation. The first enzymatic factor that processes nascent chains is peptide deformylase (PDF); it removes this formyl group as polypeptides emerge from the ribosomal tunnel and before the newly synthesized proteins can adopt their native fold, which may bury the N terminus. Next, the N-terminal methionine is excised by methionine aminopeptidase. Bacterial PDFs are metalloproteases sharing a conserved N-terminal catalytic domain. All Gram-negative bacteria, including Escherichia coli, possess class-1 PDFs characterized by a carboxy-terminal alpha-helical extension. Studies focusing on PDF as a target for antibacterial drugs have not revealed the mechanism of its co-translational mode of action despite indications in early work that it co-purifies with ribosomes. Here we provide biochemical evidence that E. coli PDF interacts directly with the ribosome via its C-terminal extension. Crystallographic analysis of the complex between the ribosome-interacting helix of PDF and the ribosome at 3.7 A resolution reveals that the enzyme orients its active site towards the ribosomal tunnel exit for efficient co-translational processing of emerging nascent chains. Furthermore, we have found that the interaction of PDF with the ribosome enhances cell viability. These results provide the structural basis for understanding the coupling between protein synthesis and enzymatic processing of nascent chains, and offer insights into the interplay of PDF with the ribosome-associated chaperone trigger factor.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bingel-Erlenmeyer, Rouven -- Kohler, Rebecca -- Kramer, Gunter -- Sandikci, Arzu -- Antolic, Snjezana -- Maier, Timm -- Schaffitzel, Christiane -- Wiedmann, Brigitte -- Bukau, Bernd -- Ban, Nenad -- England -- Nature. 2008 Mar 6;452(7183):108-11. doi: 10.1038/nature06683. Epub 2008 Feb 20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18288106" target="_blank"〉PubMed〈/a〉
    Keywords: Amidohydrolases/*chemistry/deficiency/genetics/*metabolism ; Amino Acid Sequence ; Arabinose/metabolism ; Binding Sites ; Crystallography, X-Ray ; Escherichia coli/*enzymology/genetics/growth & development/metabolism ; Genetic Complementation Test ; Models, Biological ; Models, Molecular ; Molecular Sequence Data ; N-Formylmethionine/metabolism ; Peptidylprolyl Isomerase/metabolism ; Protein Binding ; *Protein Biosynthesis ; *Protein Processing, Post-Translational ; Protein Structure, Secondary ; RNA, Transfer, Met/genetics/metabolism ; Ribosome Subunits/chemistry/metabolism ; Ribosomes/*chemistry/*metabolism
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  • 20
    Publication Date: 2008-10-31
    Description: It has long been known that the 5' to 3' polarity of DNA synthesis results in both a leading and lagging strand at all replication forks. Until now, however, there has been no evidence that leading or lagging strands are spatially organized in any way within a cell. Here we show that chromosome segregation in Escherichia coli is not random but is driven in a manner that results in the leading and lagging strands being addressed to particular cellular destinations. These destinations are consistent with the known patterns of chromosome segregation. Our work demonstrates a new level of organization relating to the replication and segregation of the E. coli chromosome.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉White, Martin A -- Eykelenboom, John K -- Lopez-Vernaza, Manuel A -- Wilson, Emily -- Leach, David R F -- G0401313/Medical Research Council/United Kingdom -- Medical Research Council/United Kingdom -- England -- Nature. 2008 Oct 30;455(7217):1248-50. doi: 10.1038/nature07282.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, King's Buildings, Edinburgh EH9 3JR, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18972020" target="_blank"〉PubMed〈/a〉
    Keywords: Cephalexin/pharmacology ; *Chromosome Segregation ; Chromosomes, Bacterial/*genetics/*metabolism ; DNA Replication ; DNA, Bacterial/biosynthesis/genetics ; Deoxyribonucleases/metabolism ; Enzyme Induction/drug effects ; Escherichia coli/*cytology/enzymology/*genetics ; Escherichia coli Proteins/metabolism ; Exonucleases/metabolism ; Models, Biological
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  • 21
    Publication Date: 2008-04-25
    Description: Bacteriophage lambda has for many years been a model system for understanding mechanisms of gene regulation. A 'genetic switch' enables the phage to transition from lysogenic growth to lytic development when triggered by specific environmental conditions. The key component of the switch is the cI repressor, which binds to two sets of three operator sites on the lambda chromosome that are separated by about 2,400 base pairs (bp). A hallmark of the lambda system is the pairwise cooperativity of repressor binding. In the absence of detailed structural information, it has been difficult to understand fully how repressor molecules establish the cooperativity complex. Here we present the X-ray crystal structure of the intact lambda cI repressor dimer bound to a DNA operator site. The structure of the repressor, determined by multiple isomorphous replacement methods, reveals an unusual overall architecture that allows it to adopt a conformation that appears to facilitate pairwise cooperative binding to adjacent operator sites.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stayrook, Steven -- Jaru-Ampornpan, Peera -- Ni, Jenny -- Hochschild, Ann -- Lewis, Mitchell -- R01 GM044025/GM/NIGMS NIH HHS/ -- England -- Nature. 2008 Apr 24;452(7190):1022-5. doi: 10.1038/nature06831.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, 37th and Hamilton Walk, Philadelphia, Pennsylvania 19102-6059, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18432246" target="_blank"〉PubMed〈/a〉
    Keywords: Allosteric Regulation ; Allosteric Site ; Bacteriophage lambda/*chemistry/genetics ; Crystallography, X-Ray ; DNA-Binding Proteins/*chemistry/*metabolism ; Dimerization ; Models, Biological ; *Models, Molecular ; Operator Regions, Genetic/*genetics ; Protein Conformation ; Repressor Proteins/*chemistry/*metabolism ; Structure-Activity Relationship ; Viral Regulatory and Accessory Proteins/*chemistry/*metabolism
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  • 22
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    Nature Publishing Group (NPG)
    Publication Date: 2008-01-18
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gottlinger, Heinrich G -- England -- Nature. 2008 Jan 24;451(7177):406-8. doi: 10.1038/nature06364.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18200012" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, CD/chemistry/*metabolism ; Cell Membrane/virology ; GPI-Linked Proteins ; HIV Infections/*metabolism/therapy/*virology ; HIV-1/drug effects/*metabolism ; Herpesvirus 8, Human/enzymology/physiology ; Human Immunodeficiency Virus Proteins/deficiency/genetics/*metabolism ; Humans ; Interferon-alpha/pharmacology ; Membrane Glycoproteins/chemistry/deficiency/*metabolism ; Models, Biological ; Ubiquitin-Protein Ligases/metabolism ; Viral Regulatory and Accessory Proteins/deficiency/genetics/*metabolism
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  • 23
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    Nature Publishing Group (NPG)
    Publication Date: 2008-08-08
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Steinbach, Joe Henry -- R01 NS022356/NS/NINDS NIH HHS/ -- England -- Nature. 2008 Aug 7;454(7205):704-5. doi: 10.1038/454704a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18685692" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Drug Partial Agonism ; Humans ; Models, Biological ; Nicotinic Agonists/*pharmacology ; Protein Conformation ; Receptors, Glycine/agonists/chemistry/metabolism ; Receptors, Nicotinic/chemistry/*metabolism
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  • 24
    Publication Date: 2008-11-07
    Description: The population cycles of rodents at northern latitudes have puzzled people for centuries, and their impact is manifest throughout the alpine ecosystem. Climate change is known to be able to drive animal population dynamics between stable and cyclic phases, and has been suggested to cause the recent changes in cyclic dynamics of rodents and their predators. But although predator-rodent interactions are commonly argued to be the cause of the Fennoscandian rodent cycles, the role of the environment in the modulation of such dynamics is often poorly understood in natural systems. Hence, quantitative links between climate-driven processes and rodent dynamics have so far been lacking. Here we show that winter weather and snow conditions, together with density dependence in the net population growth rate, account for the observed population dynamics of the rodent community dominated by lemmings (Lemmus lemmus) in an alpine Norwegian core habitat between 1970 and 1997, and predict the observed absence of rodent peak years after 1994. These local rodent dynamics are coherent with alpine bird dynamics both locally and over all of southern Norway, consistent with the influence of large-scale fluctuations in winter conditions. The relationship between commonly available meteorological data and snow conditions indicates that changes in temperature and humidity, and thus conditions in the subnivean space, seem to markedly affect the dynamics of alpine rodents and their linked groups. The pattern of less regular rodent peaks, and corresponding changes in the overall dynamics of the alpine ecosystem, thus seems likely to prevail over a growing area under projected climate change.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kausrud, Kyrre L -- Mysterud, Atle -- Steen, Harald -- Vik, Jon Olav -- Ostbye, Eivind -- Cazelles, Bernard -- Framstad, Erik -- Eikeset, Anne Maria -- Mysterud, Ivar -- Solhoy, Torstein -- Stenseth, Nils Chr -- England -- Nature. 2008 Nov 6;456(7218):93-7. doi: 10.1038/nature07442.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Centre for Ecological and Evolutionary Synthesis, University of Oslo, PO Box 1066 Blindern, N-0316 Oslo, Norway.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18987742" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Arvicolinae/*physiology ; Birds/physiology ; *Ecosystem ; *Greenhouse Effect ; History, 20th Century ; History, 21st Century ; Humidity ; Models, Biological ; Norway ; Population Dynamics ; Seasons ; Snow ; Temperature
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  • 25
    Publication Date: 2008-04-18
    Description: The evolutionary interaction between influenza A virus and the human immune system, manifest as 'antigenic drift' of the viral haemagglutinin, is one of the best described patterns in molecular evolution. However, little is known about the genome-scale evolutionary dynamics of this pathogen. Similarly, how genomic processes relate to global influenza epidemiology, in which the A/H3N2 and A/H1N1 subtypes co-circulate, is poorly understood. Here through an analysis of 1,302 complete viral genomes sampled from temperate populations in both hemispheres, we show that the genomic evolution of influenza A virus is characterized by a complex interplay between frequent reassortment and periodic selective sweeps. The A/H3N2 and A/H1N1 subtypes exhibit different evolutionary dynamics, with diverse lineages circulating in A/H1N1, indicative of weaker antigenic drift. These results suggest a sink-source model of viral ecology in which new lineages are seeded from a persistent influenza reservoir, which we hypothesize to be located in the tropics, to sink populations in temperate regions.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2441973/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2441973/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Rambaut, Andrew -- Pybus, Oliver G -- Nelson, Martha I -- Viboud, Cecile -- Taubenberger, Jeffery K -- Holmes, Edward C -- Z01 AI000996-01/Intramural NIH HHS/ -- England -- Nature. 2008 May 29;453(7195):615-9. doi: 10.1038/nature06945. Epub 2008 Apr 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Evolutionary Biology, University of Edinburgh, Ashworth Laboratories, Edinburgh EH9 3JT, UK. a.rambaut@ed.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18418375" target="_blank"〉PubMed〈/a〉
    Keywords: *Evolution, Molecular ; Genetic Drift ; Genetic Variation ; Genome, Viral/*genetics ; Hemagglutinin Glycoproteins, Influenza Virus/genetics ; Humans ; Influenza A Virus, H1N1 Subtype/*genetics/immunology ; Influenza A Virus, H3N2 Subtype/*genetics/immunology ; Influenza, Human/*epidemiology/*virology ; Models, Biological ; Neuraminidase/genetics ; New York/epidemiology ; New Zealand/epidemiology ; Phylogeny ; Reassortant Viruses/genetics/immunology
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  • 26
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    Nature Publishing Group (NPG)
    Publication Date: 2008-05-03
    Description: The universality of ribonuclease P (RNase P), the ribonucleoprotein essential for transfer RNA (tRNA) 5' maturation, is challenged in the archaeon Nanoarchaeum equitans. Neither extensive computational analysis of the genome nor biochemical tests in cell extracts revealed the existence of this enzyme. Here we show that the conserved placement of its tRNA gene promoters allows the synthesis of leaderless tRNAs, whose presence was verified by the observation of 5' triphosphorylated mature tRNA species. Initiation of tRNA gene transcription requires a purine, which coincides with the finding that tRNAs with a cytosine in position 1 display unusually extended 5' termini with an extra purine residue. These tRNAs were shown to be substrates for their cognate aminoacyl-tRNA synthetases. These findings demonstrate how nature can cope with the loss of the universal and supposedly ancient RNase P through genomic rearrangement at tRNA genes under the pressure of genome condensation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Randau, Lennart -- Schroder, Imke -- Soll, Dieter -- England -- Nature. 2008 May 1;453(7191):120-3. doi: 10.1038/nature06833.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18451863" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acyl-tRNA Synthetases/metabolism ; Aminoacylation ; Base Sequence ; *Evolution, Molecular ; Gene Deletion ; Genes, Archaeal/*genetics ; Models, Biological ; Molecular Sequence Data ; Nanoarchaeota/cytology/enzymology/*genetics ; Phosphorylation ; Promoter Regions, Genetic/*genetics ; RNA, Archaeal/*genetics/metabolism ; RNA, Transfer/*genetics/metabolism ; Ribonuclease P/*deficiency/metabolism ; Substrate Specificity ; Transcription, Genetic/genetics
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  • 27
    Publication Date: 2008-10-31
    Description: A long-standing issue in ecology is reconciling the apparent stability of many populations with robust predictions of large-amplitude population cycles from general theory on consumer-resource interactions. Even when consumers are decoupled from dynamic resources, large-amplitude cycles can theoretically emerge from delayed feedback processes found in many consumers. Here we show that resource-dependent mortality and a dynamic developmental delay in consumers produces a new type of small-amplitude cycle that coexists with large-amplitude fluctuations in coupled consumer-resource systems. A distinctive characteristic of the small-amplitude cycles is slow juvenile development for consumers, leading to a developmental delay that is longer than the cycle period. By contrast, the period exceeds the delay in large-amplitude cycles. These theoretical predictions may explain previous empirical results on coexisting attractors found in Daphnia-algal systems. To test this, we used bioassay experiments that measure the growth rates of individuals in populations exhibiting each type of cycle. The results were consistent with predictions. Together, the new theory and experiments establish that two very general features of consumers--a resource-dependent juvenile stage duration and resource-dependent mortality--combine to produce small-amplitude resource-consumer cycles. This phenomenon may contribute to the prevalence of small-amplitude fluctuations in many other consumer-resource populations.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McCauley, Edward -- Nelson, William A -- Nisbet, Roger M -- England -- Nature. 2008 Oct 30;455(7217):1240-3. doi: 10.1038/nature07220.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Ecology and Evolution Group, Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada. mccauley@ucalgary.ca〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18972019" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biological Assay ; Daphnia/growth & development/*physiology ; Eukaryota/*physiology ; Female ; *Food Chain ; Models, Biological ; Ovum/physiology
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  • 28
    Publication Date: 2008-05-24
    Description: The shape of motile cells is determined by many dynamic processes spanning several orders of magnitude in space and time, from local polymerization of actin monomers at subsecond timescales to global, cell-scale geometry that may persist for hours. Understanding the mechanism of shape determination in cells has proved to be extremely challenging due to the numerous components involved and the complexity of their interactions. Here we harness the natural phenotypic variability in a large population of motile epithelial keratocytes from fish (Hypsophrys nicaraguensis) to reveal mechanisms of shape determination. We find that the cells inhabit a low-dimensional, highly correlated spectrum of possible functional states. We further show that a model of actin network treadmilling in an inextensible membrane bag can quantitatively recapitulate this spectrum and predict both cell shape and speed. Our model provides a simple biochemical and biophysical basis for the observed morphology and behaviour of motile cells.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2877812/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2877812/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Keren, Kinneret -- Pincus, Zachary -- Allen, Greg M -- Barnhart, Erin L -- Marriott, Gerard -- Mogilner, Alex -- Theriot, Julie A -- U54 GM064346/GM/NIGMS NIH HHS/ -- U54 GM064346-099040/GM/NIGMS NIH HHS/ -- U54 GM64346/GM/NIGMS NIH HHS/ -- England -- Nature. 2008 May 22;453(7194):475-80. doi: 10.1038/nature06952.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, Technion- Israel Institute of Technology, Haifa 32000, Israel.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18497816" target="_blank"〉PubMed〈/a〉
    Keywords: Actin Cytoskeleton/chemistry/metabolism ; Actins/chemistry/metabolism ; Animals ; Biophysical Phenomena ; Biophysics ; Cell Membrane/chemistry/metabolism ; Cell Movement/*physiology ; Cell Shape/*physiology ; Cells, Cultured ; *Cichlids ; Epithelial Cells/*cytology ; Models, Biological ; Pseudopodia/metabolism ; Time Factors
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  • 29
    Publication Date: 2008-01-11
    Description: Explaining the rise and maintenance of cooperation is central to our understanding of biological systems and human societies. When an individual's cooperativeness is used by other individuals as a choice criterion, there can be competition to be more generous than others, a situation called competitive altruism. The evolution of cooperation between non-relatives can then be driven by a positive feedback between increasing levels of cooperativeness and choosiness. Here we use evolutionary simulations to show that, in a situation where individuals have the opportunity to engage in repeated pairwise interactions, the equilibrium degree of cooperativeness depends critically on the amount of behavioural variation that is being maintained in the population by processes such as mutation. Because our model does not invoke complex mechanisms such as negotiation behaviour, it can be applied to a wide range of species. The results suggest an important role of lifespan in the evolution of cooperation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McNamara, John M -- Barta, Zoltan -- Fromhage, Lutz -- Houston, Alasdair I -- England -- Nature. 2008 Jan 10;451(7175):189-92. doi: 10.1038/nature06455.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Mathematics, University of Bristol, University Walk, Bristol BS8 1TW, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18185587" target="_blank"〉PubMed〈/a〉
    Keywords: Altruism ; Animals ; *Biological Evolution ; Choice Behavior/*physiology ; Competitive Behavior/physiology ; *Cooperative Behavior ; Game Theory ; Humans ; Longevity ; Models, Biological ; Mutagenesis ; Reproduction/genetics/physiology
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  • 30
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    Nature Publishing Group (NPG)
    Publication Date: 2008-07-25
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Woodward, F I -- England -- Nature. 2008 Jul 24;454(7203):422-3. doi: 10.1038/454422a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18650910" target="_blank"〉PubMed〈/a〉
    Keywords: Cellulose/chemistry/metabolism ; Humidity ; Models, Biological ; Oxygen Isotopes ; Plant Leaves/*physiology ; *Temperature ; Trees/*physiology
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  • 31
    Publication Date: 2008-05-30
    Description: Malaria parasites and related Apicomplexans are the causative agents of the some of the most serious infectious diseases of humans, companion animals, livestock and wildlife. These parasites must undergo sexual reproduction to transmit from vertebrate hosts to vectors, and their sex ratios are consistently female-biased. Sex allocation theory, a cornerstone of evolutionary biology, is remarkably successful at explaining female-biased sex ratios in multicellular taxa, but has proved controversial when applied to malaria parasites. Here we show that, as predicted by theory, sex ratio is an important fitness-determining trait and Plasmodium chabaudi parasites adjust their sex allocation in response to the presence of unrelated conspecifics. This suggests that P. chabaudi parasites use kin discrimination to evaluate the genetic diversity of their infections, and they adjust their behaviour in response to environmental cues. Malaria parasites provide a novel way to test evolutionary theory, and support the generality and power of a darwinian approach.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3807728/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3807728/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reece, Sarah E -- Drew, Damien R -- Gardner, Andy -- Biotechnology and Biological Sciences Research Council/United Kingdom -- Wellcome Trust/United Kingdom -- England -- Nature. 2008 May 29;453(7195):609-14. doi: 10.1038/nature06954.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Evolutionary Biology, Ashworth Laboratories, School of Biological Science, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK. sarah.reece@ed.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18509435" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; Cues ; Female ; Fertility/genetics/physiology ; Genetic Variation ; Genotype ; Humans ; Malaria/*parasitology ; Male ; Models, Biological ; Plasmodium chabaudi/genetics/*physiology ; *Sex Ratio
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  • 32
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    Nature Publishing Group (NPG)
    Publication Date: 2008-11-21
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bowles, Samuel -- England -- Nature. 2008 Nov 20;456(7220):326-7. doi: 10.1038/456326a.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Behavioral Sciences Program at the Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501, USA. bowles@santafe.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19020603" target="_blank"〉PubMed〈/a〉
    Keywords: *Altruism ; Animals ; Biological Evolution ; *Conflict (Psychology) ; *Cooperative Behavior ; *Human Characteristics ; Humans ; Models, Biological ; Violence/psychology/statistics & numerical data ; Warfare
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  • 33
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    Nature Publishing Group (NPG)
    Publication Date: 2008-02-08
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kirkwood, Thomas B L -- BB/C008200/1/Biotechnology and Biological Sciences Research Council/United Kingdom -- England -- Nature. 2008 Feb 7;451(7179):644-7. doi: 10.1038/451644a.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University, Newcastle upon Tyne, UK. tom.kirkwood@ncl.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18256658" target="_blank"〉PubMed〈/a〉
    Keywords: Age Distribution ; Aging/*physiology ; Animals ; Caenorhabditis elegans/genetics/physiology ; DNA Damage ; Disease Models, Animal ; Geriatrics/trends ; Health ; Humans ; *Life Expectancy/trends ; Longevity/physiology ; Mice ; Models, Biological ; Neoplasms/epidemiology/pathology ; *Systems Biology ; Werner Syndrome/genetics/pathology
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  • 34
    Publication Date: 2008-04-25
    Description: One of the most dramatic perturbations to the Earth system during the past 100 million years was the rapid onset of Antarctic glaciation near the Eocene/Oligocene epoch boundary (approximately 34 million years ago). This climate transition was accompanied by a deepening of the calcite compensation depth--the ocean depth at which the rate of calcium carbonate input from surface waters equals the rate of dissolution. Changes in the global carbon cycle, rather than changes in continental configuration, have recently been proposed as the most likely root cause of Antarctic glaciation, but the mechanism linking glaciation to the deepening of calcite compensation depth remains unclear. Here we use a global biogeochemical box model to test competing hypotheses put forward to explain the Eocene/Oligocene transition. We find that, of the candidate hypotheses, only shelf to deep sea carbonate partitioning is capable of explaining the observed changes in both carbon isotope composition and calcium carbonate accumulation at the sea floor. In our simulations, glacioeustatic sea-level fall associated with the growth of Antarctic ice sheets permanently reduces global calcium carbonate accumulation on the continental shelves, leading to an increase in pelagic burial via permanent deepening of the calcite compensation depth. At the same time, fresh limestones are exposed to erosion, thus temporarily increasing global river inputs of dissolved carbonate and increasing seawater delta13C. Our work sheds new light on the mechanisms linking glaciation and ocean acidity change across arguably the most important climate transition of the Cenozoic era.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Merico, Agostino -- Tyrrell, Toby -- Wilson, Paul A -- England -- Nature. 2008 Apr 24;452(7190):979-82. doi: 10.1038/nature06853.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉National Oceanography Centre, Southampton, European Way, Southampton SO14 3ZH, UK. agostino.merico@gkss.de〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18432242" target="_blank"〉PubMed〈/a〉
    Keywords: Acids/analysis ; Antarctic Regions ; Atmosphere/chemistry ; Calcium Carbonate/analysis/metabolism ; Carbon/analysis/metabolism ; Carbon Isotopes ; Diatoms/metabolism ; Geologic Sediments/chemistry ; History, Ancient ; Hydrogen-Ion Concentration ; *Ice Cover ; Models, Biological ; Oceans and Seas ; Phytoplankton/metabolism ; Seawater/*analysis/*chemistry ; Time Factors
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  • 35
    Publication Date: 2008-05-09
    Description: Mammalian lungs are branched networks containing thousands to millions of airways arrayed in intricate patterns that are crucial for respiration. How such trees are generated during development, and how the developmental patterning information is encoded, have long fascinated biologists and mathematicians. However, models have been limited by a lack of information on the normal sequence and pattern of branching events. Here we present the complete three-dimensional branching pattern and lineage of the mouse bronchial tree, reconstructed from an analysis of hundreds of developmental intermediates. The branching process is remarkably stereotyped and elegant: the tree is generated by three geometrically simple local modes of branching used in three different orders throughout the lung. We propose that each mode of branching is controlled by a genetically encoded subroutine, a series of local patterning and morphogenesis operations, which are themselves controlled by a more global master routine. We show that this hierarchical and modular programme is genetically tractable, and it is ideally suited to encoding and evolving the complex networks of the lung and other branched organs.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2892995/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2892995/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Metzger, Ross J -- Klein, Ophir D -- Martin, Gail R -- Krasnow, Mark A -- R01 CA078711/CA/NCI NIH HHS/ -- R01 CA078711-02/CA/NCI NIH HHS/ -- R01 CA078711-03/CA/NCI NIH HHS/ -- R01 CA078711-04/CA/NCI NIH HHS/ -- R01 CA078711-05/CA/NCI NIH HHS/ -- R01 HL075769/HL/NHLBI NIH HHS/ -- R01 HL075769-01/HL/NHLBI NIH HHS/ -- R01 HL075769-02/HL/NHLBI NIH HHS/ -- R01 HL075769-03/HL/NHLBI NIH HHS/ -- R01 HL075769-04/HL/NHLBI NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2008 Jun 5;453(7196):745-50. doi: 10.1038/nature07005. Epub 2008 May 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and HHMI, Stanford University School of Medicine, Stanford, California 94305-5307, USA. ross.metzger@ucsf.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18463632" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptor Proteins, Signal Transducing ; Animals ; Body Patterning/genetics/*physiology ; Fibroblast Growth Factor 10/metabolism ; Intracellular Signaling Peptides and Proteins ; Lung/*anatomy & histology/cytology/*embryology/metabolism ; Membrane Proteins/metabolism ; Mice ; Models, Biological ; Organogenesis/genetics/*physiology ; Receptor, Fibroblast Growth Factor, Type 2/genetics/metabolism
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  • 36
    Publication Date: 2008-09-23
    Description: DNA ends exposed after introduction of double-strand breaks (DSBs) undergo 5'-3' nucleolytic degradation to generate single-stranded DNA, the substrate for binding by the Rad51 protein to initiate homologous recombination. This process is poorly understood in eukaryotes, but several factors have been implicated, including the Mre11 complex (Mre11-Rad50-Xrs2/NBS1), Sae2/CtIP/Ctp1 and Exo1. Here we demonstrate that yeast Exo1 nuclease and Sgs1 helicase function in alternative pathways for DSB processing. Novel, partially resected intermediates accumulate in a double mutant lacking Exo1 and Sgs1, which are poor substrates for homologous recombination. The early processing step that generates partly resected intermediates is dependent on Sae2. When Sae2 is absent, in addition to Exo1 and Sgs1, unprocessed DSBs accumulate and homology-dependent repair fails. These results suggest a two-step mechanism for DSB processing during homologous recombination. First, the Mre11 complex and Sae2 remove a small oligonucleotide(s) from the DNA ends to form an early intermediate. Second, Exo1 and/or Sgs1 rapidly process this intermediate to generate extensive tracts of single-stranded DNA that serve as substrate for Rad51.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3818707/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3818707/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mimitou, Eleni P -- Symington, Lorraine S -- R01 GM041784/GM/NIGMS NIH HHS/ -- R01 GM041784-19/GM/NIGMS NIH HHS/ -- R01 GM041784-20/GM/NIGMS NIH HHS/ -- R01 GM041784-21/GM/NIGMS NIH HHS/ -- England -- Nature. 2008 Oct 9;455(7214):770-4. doi: 10.1038/nature07312. Epub 2008 Sep 21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology, Columbia University Medical Center, 701 West 168th Street, New York, New York 10032, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18806779" target="_blank"〉PubMed〈/a〉
    Keywords: *DNA Breaks, Double-Stranded ; *DNA Repair ; Endodeoxyribonucleases/metabolism ; Endonucleases ; Exodeoxyribonucleases/genetics/*metabolism ; Models, Biological ; Rad51 Recombinase/genetics/metabolism ; RecQ Helicases/genetics/*metabolism ; Recombination, Genetic ; Saccharomyces cerevisiae/*genetics/*metabolism ; Saccharomyces cerevisiae Proteins/genetics/*metabolism
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  • 37
    Publication Date: 2008-01-19
    Description: In nature, self-assembling and disassembling complexes of proteins and nucleic acids bound to a variety of ligands perform intricate and diverse dynamic functions. In contrast, attempts to rationally encode structure and function into synthetic amino acid and nucleic acid sequences have largely focused on engineering molecules that self-assemble into prescribed target structures, rather than on engineering transient system dynamics. To design systems that perform dynamic functions without human intervention, it is necessary to encode within the biopolymer sequences the reaction pathways by which self-assembly occurs. Nucleic acids show promise as a design medium for engineering dynamic functions, including catalytic hybridization, triggered self-assembly and molecular computation. Here, we program diverse molecular self-assembly and disassembly pathways using a 'reaction graph' abstraction to specify complementarity relationships between modular domains in a versatile DNA hairpin motif. Molecular programs are executed for a variety of dynamic functions: catalytic formation of branched junctions, autocatalytic duplex formation by a cross-catalytic circuit, nucleated dendritic growth of a binary molecular 'tree', and autonomous locomotion of a bipedal walker.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yin, Peng -- Choi, Harry M T -- Calvert, Colby R -- Pierce, Niles A -- England -- Nature. 2008 Jan 17;451(7176):318-22. doi: 10.1038/nature06451.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Bioengineering, California Institute of Technology, Pasadena, California 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18202654" target="_blank"〉PubMed〈/a〉
    Keywords: Biopolymers/chemistry/metabolism ; Catalysis ; *Computer Simulation ; DNA/*chemistry/*metabolism ; DNA, Concatenated/chemistry/metabolism ; Dendrimers/chemistry/metabolism ; Gait ; Kinetics ; Models, Biological ; *Nucleic Acid Conformation ; Stochastic Processes ; Walking
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  • 38
    Publication Date: 2008-10-10
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Koentges, Georgy -- England -- Nature. 2008 Oct 9;455(7214):747-8. doi: 10.1038/455747a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18843358" target="_blank"〉PubMed〈/a〉
    Keywords: Ambystoma mexicanum/*embryology ; Animals ; Ectoderm/*cytology/embryology ; Endoderm/*cytology/embryology ; Epithelium/*embryology ; Models, Biological ; Morphogenesis ; Tooth/*cytology/*embryology
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  • 39
    Publication Date: 2008-01-25
    Description: Translocation of many soluble proteins across cell membranes occurs in an ATPase-driven manner. For construction of the bacterial flagellum responsible for motility, most of the components are exported by the flagellar protein export apparatus. The FliI ATPase is required for this export, and its ATPase activity is regulated by FliH; however, it is unclear how the chemical energy derived from ATP hydrolysis is used for the export process. Here we report that flagellar proteins of Salmonella enterica serovar Typhimurium are exported even in the absence of FliI. A fliH fliI double null mutant was weakly motile. Certain mutations in FlhA or FlhB, which form the core of the export gate, substantially improved protein export and motility of the double null mutant. Furthermore, proton motive force was essential for the export process. These results suggest that the FliH-FliI complex facilitates only the initial entry of export substrates into the gate, with the energy of ATP hydrolysis being used to disassemble and release the FliH-FliI complex from the protein about to be exported. The rest of the successive unfolding/translocation process of the substrates is driven by proton motive force.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Minamino, Tohru -- Namba, Keiichi -- England -- Nature. 2008 Jan 24;451(7177):485-8. doi: 10.1038/nature06449.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18216858" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Bacterial Proteins/genetics/*metabolism/secretion ; Carbonyl Cyanide m-Chlorophenyl Hydrazone/pharmacology ; Flagella/chemistry/metabolism/*secretion ; Hydrolysis/drug effects ; Membrane Proteins/genetics/metabolism ; Models, Biological ; Mutant Proteins/genetics/metabolism ; Mutation/genetics ; Protein Transport/drug effects ; Proton-Motive Force/drug effects/*physiology ; Proton-Translocating ATPases/deficiency/genetics/*metabolism ; Salmonella typhimurium/cytology/enzymology/genetics/*metabolism
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  • 40
    Publication Date: 2008-03-21
    Description: To understand the processes that regulate the abundance and persistence of wild populations is a fundamental goal of ecology and a prerequisite for the management of living resources. Variable abundance data, however, make the demonstration of regulation processes challenging. A previously overlooked aspect in understanding how populations are regulated is the possibility that the pattern of variability--its strength as a function of population size--may be more than 'noise', thus revealing much about the characteristics of population regulation. Here we show that patterns in survival variability do provide evidence of regulation through density. Using a large, global compilation of marine, anadromous and freshwater fisheries data, we examine the relationship between the variability of survival and population abundance. The interannual variability in progeny survival increases at low adult abundance in an inversely density-dependent fashion. This pattern is consistent with models in which density dependence enters after the larval stage. The findings are compatible with very simple forms of density dependence: even a linear increase of juvenile mortality with adult density adequately explains the results. The model predictions explain why populations with strong regulation may experience large increases in variability at low densities. Furthermore, the inverse relationship between survival variability and the strength of density dependence has important consequences for fisheries management and recovery, and population persistence or extinction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Minto, Coilin -- Myers, Ransom A -- Blanchard, Wade -- England -- Nature. 2008 Mar 20;452(7185):344-7. doi: 10.1038/nature06605.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4J1, Canada. mintoc@mathstat.dal.ca〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18354480" target="_blank"〉PubMed〈/a〉
    Keywords: Age Distribution ; Aging ; Animals ; Fishes/growth & development/*physiology ; Geography ; Larva/physiology ; Models, Biological ; Oceans and Seas ; Population Density ; Reproduction ; Stochastic Processes ; Survival Rate
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  • 41
    Publication Date: 2008-01-19
    Description: Spastin, the most common locus for mutations in hereditary spastic paraplegias, and katanin are related microtubule-severing AAA ATPases involved in constructing neuronal and non-centrosomal microtubule arrays and in segregating chromosomes. The mechanism by which spastin and katanin break and destabilize microtubules is unknown, in part owing to the lack of structural information on these enzymes. Here we report the X-ray crystal structure of the Drosophila spastin AAA domain and provide a model for the active spastin hexamer generated using small-angle X-ray scattering combined with atomic docking. The spastin hexamer forms a ring with a prominent central pore and six radiating arms that may dock onto the microtubule. Helices unique to the microtubule-severing AAA ATPases surround the entrances to the pore on either side of the ring, and three highly conserved loops line the pore lumen. Mutagenesis reveals essential roles for these structural elements in the severing reaction. Peptide and antibody inhibition experiments further show that spastin may dismantle microtubules by recognizing specific features in the carboxy-terminal tail of tubulin. Collectively, our data support a model in which spastin pulls the C terminus of tubulin through its central pore, generating a mechanical force that destabilizes tubulin-tubulin interactions within the microtubule lattice. Our work also provides insights into the structural defects in spastin that arise from mutations identified in hereditary spastic paraplegia patients.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2882799/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2882799/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Roll-Mecak, Antonina -- Vale, Ronald D -- K99 NS057934-01/NS/NINDS NIH HHS/ -- K99 NS057934-02/NS/NINDS NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2008 Jan 17;451(7176):363-7. doi: 10.1038/nature06482.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, 600 16th Street, San Francisco, California 94158, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18202664" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphatases/antagonists & ; inhibitors/*chemistry/*genetics/*metabolism ; Animals ; Drosophila Proteins/antagonists & inhibitors/*chemistry/genetics/*metabolism ; Humans ; Microtubules/chemistry/*metabolism ; Models, Biological ; Models, Molecular ; Protein Structure, Quaternary ; Protein Structure, Tertiary ; Scattering, Small Angle ; Spastic Paraplegia, Hereditary/*genetics ; Structure-Activity Relationship ; Substrate Specificity ; Tubulin/chemistry/metabolism ; X-Ray Diffraction
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  • 42
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    Nature Publishing Group (NPG)
    Publication Date: 2008-11-21
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Misteli, Tom -- England -- Nature. 2008 Nov 20;456(7220):333-4. doi: 10.1038/456333a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19020607" target="_blank"〉PubMed〈/a〉
    Keywords: *Cell Compartmentation ; Coiled Bodies/*metabolism ; Models, Biological ; Stochastic Processes
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  • 43
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    Nature Publishing Group (NPG)
    Publication Date: 2008-03-07
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tice, Michael M -- England -- Nature. 2008 Mar 6;452(7183):40-1. doi: 10.1038/452040a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18322521" target="_blank"〉PubMed〈/a〉
    Keywords: *Ecosystem ; Fossils ; Geologic Sediments/*chemistry/*microbiology ; *Marine Biology ; Models, Biological ; Oceans and Seas ; Paleontology ; Seawater/*microbiology ; Silicon Dioxide/chemistry ; South Africa ; Time Factors ; Water Movements
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  • 44
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    Nature Publishing Group (NPG)
    Publication Date: 2008-05-03
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Moore, Andrew -- England -- Nature. 2008 May 1;453(7191):31-2. doi: 10.1038/453031a.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Science & Society Programme at the European Molecular Biology Organization (EMBO), Meyerhofstrasse 1, D-69117 Heidelberg, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18451837" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; Biology/*education/history ; Computational Biology/education ; Curriculum/standards/*trends ; Evolution, Molecular ; History, 20th Century ; History, 21st Century ; Humans ; Internationality ; Models, Biological ; Teaching/history/*standards/*trends
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  • 45
    Publication Date: 2008-01-25
    Description: The evolution of avian flight remains one of biology's major controversies, with a long history of functional interpretations of fossil forms given as evidence for either an arboreal or cursorial origin of flight. Despite repeated emphasis on the 'wing-stroke' as a necessary avenue of investigation for addressing the evolution of flight, no empirical data exist on wing-stroke dynamics in an experimental evolutionary context. Here we present the first comparison of wing-stroke kinematics of the primary locomotor modes (descending flight and incline flap-running) that lead to level-flapping flight in juvenile ground birds throughout development. We offer results that are contrary both to popular perception and inferences from other studies. Starting shortly after hatching and continuing through adulthood, ground birds use a wing-stroke confined to a narrow range of less than 20 degrees , when referenced to gravity, that directs aerodynamic forces about 40 degrees above horizontal, permitting a 180 degrees range in the direction of travel. Based on our results, we put forth an ontogenetic-transitional wing hypothesis that posits that the incremental adaptive stages leading to the evolution of avian flight correspond behaviourally and morphologically to transitional stages observed in ontogenetic forms.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Dial, Kenneth P -- Jackson, Brandon E -- Segre, Paolo -- England -- Nature. 2008 Feb 21;451(7181):985-9. doi: 10.1038/nature06517. Epub 2008 Jan 23.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Flight Laboratory, Division of Biological Sciences, University of Montana, 32 Campus Drive, Missoula, Montana 59812, USA. kdial@mso.umt.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18216784" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; Biomechanical Phenomena ; Flight, Animal/*physiology ; Galliformes/growth & development/*physiology ; Locomotion/physiology ; Models, Biological ; Wings, Animal/*physiology
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  • 46
    Publication Date: 2008-10-17
    Description: Service providers may vary service quality depending on whether they work alone or provide the service simultaneously with a partner. The latter case resembles a prisoner's dilemma, in which one provider may try to reap the benefits of the interaction without providing the service. Here we present a game-theory model based on the marginal value theorem, which predicts that as long as the client determines the duration, and the providers cooperate towards mutual gain, service quality will increase in the pair situation. This prediction is consistent with field observations and with an experiment on cleaning mutualism, in which stable male-female pairs of the cleaner wrasse Labroides dimidiatus repeatedly inspect client fish jointly. Cleaners cooperate by eating ectoparasites off clients but actually prefer to cheat and eat client mucus. Because clients often leave in response to such cheating, the benefits of cheating can be gained by only one cleaner during a pair inspection. In both data sets, the increased service quality during pair inspection was mainly due to the smaller females behaving significantly more cooperatively than their larger male partners. In contrast, during solitary inspections, cleaning behaviour was very similar between the sexes. Our study highlights the importance of incorporating interactions between service providers to make more quantitative predictions about cooperation between species.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bshary, Redouan -- Grutter, Alexandra S -- Willener, Astrid S T -- Leimar, Olof -- England -- Nature. 2008 Oct 16;455(7215):964-6. doi: 10.1038/nature07184.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉University of Neuchatel, Department of Zoology, Rue Emile-Argand 11 Case postale 158, 2009 Neuchatel, Switzerland. redouan.bshary@unine.ch〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18923522" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Cooperative Behavior ; Feeding Behavior/*physiology ; Female ; Fishes/*physiology ; Game Theory ; Male ; Models, Biological ; Mucus ; *Parasites ; Sex Characteristics ; Swimming/physiology ; *Symbiosis
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  • 47
    Publication Date: 2008-10-17
    Description: Most proteins are secreted from bacteria by the interaction of the cytoplasmic SecA ATPase with a membrane channel, formed by the heterotrimeric SecY complex. Here we report the crystal structure of SecA bound to the SecY complex, with a maximum resolution of 4.5 angstrom (A), obtained for components from Thermotoga maritima. One copy of SecA in an intermediate state of ATP hydrolysis is bound to one molecule of the SecY complex. Both partners undergo important conformational changes on interaction. The polypeptide-cross-linking domain of SecA makes a large conformational change that could capture the translocation substrate in a 'clamp'. Polypeptide movement through the SecY channel could be achieved by the motion of a 'two-helix finger' of SecA inside the cytoplasmic funnel of SecY, and by the coordinated tightening and widening of SecA's clamp above the SecY pore. SecA binding generates a 'window' at the lateral gate of the SecY channel and it displaces the plug domain, preparing the channel for signal sequence binding and channel opening.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zimmer, Jochen -- Nam, Yunsun -- Rapoport, Tom A -- Howard Hughes Medical Institute/ -- England -- Nature. 2008 Oct 16;455(7215):936-43. doi: 10.1038/nature07335.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18923516" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphatases/*chemistry/*metabolism ; Adenosine Triphosphate/metabolism ; Bacillus subtilis/chemistry ; Bacterial Proteins/*chemistry/*metabolism ; Crystallography, X-Ray ; Hydrolysis ; Membrane Transport Proteins/*chemistry/*metabolism ; Models, Biological ; Models, Molecular ; Movement ; Multiprotein Complexes/chemistry/metabolism ; Protein Binding ; Protein Conformation ; Protein Sorting Signals/physiology ; Protein Transport ; Structure-Activity Relationship ; Thermotoga maritima/*chemistry
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  • 48
    Publication Date: 2008-11-28
    Description: Gibberellins control a range of growth and developmental processes in higher plants and have been widely used in the agricultural industry. By binding to a nuclear receptor, GIBBERELLIN INSENSITIVE DWARF1 (GID1), gibberellins regulate gene expression by promoting degradation of the transcriptional regulator DELLA proteins, including GIBBERELLIN INSENSITIVE (GAI). The precise manner in which GID1 discriminates and becomes activated by bioactive gibberellins for specific binding to DELLA proteins remains unclear. Here we present the crystal structure of a ternary complex of Arabidopsis thaliana GID1A, a bioactive gibberellin and the amino-terminal DELLA domain of GAI. In this complex, GID1A occludes gibberellin in a deep binding pocket covered by its N-terminal helical switch region, which in turn interacts with the DELLA domain containing DELLA, VHYNP and LExLE motifs. Our results establish a structural model of a plant hormone receptor that is distinct from the mechanism of the hormone perception and effector recognition of the known auxin receptors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Murase, Kohji -- Hirano, Yoshinori -- Sun, Tai-ping -- Hakoshima, Toshio -- England -- Nature. 2008 Nov 27;456(7221):459-63. doi: 10.1038/nature07519.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Structural Biology Laboratory, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19037309" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Motifs ; Arabidopsis/*chemistry/metabolism ; Arabidopsis Proteins/*chemistry/genetics/*metabolism ; Circular Dichroism ; Crystallography, X-Ray ; Gibberellins/metabolism/*pharmacology ; Models, Biological ; Models, Molecular ; Plant Growth Regulators/metabolism/*pharmacology ; Protein Binding ; Protein Structure, Tertiary/drug effects ; Receptors, Cell Surface/*chemistry/genetics/*metabolism ; Substrate Specificity
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  • 49
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    Nature Publishing Group (NPG)
    Publication Date: 2008-01-11
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tollefson, Jeff -- England -- Nature. 2008 Jan 10;451(7175):113. doi: 10.1038/451113a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18185549" target="_blank"〉PubMed〈/a〉
    Keywords: Agriculture/methods/*trends ; Atmosphere/*chemistry ; Bioelectric Energy Sources/trends ; *Biomass ; Carbon Dioxide/*analysis ; *Greenhouse Effect ; Models, Biological
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  • 50
    Publication Date: 2008-10-17
    Description: Among the morphological changes that occurred during the 'fish-to-tetrapod' transition was a marked reorganization of the cranial endoskeleton. Details of this transition, including the sequence of character acquisition, have not been evident from the fossil record. Here we describe the braincase, palatoquadrate and branchial skeleton of Tiktaalik roseae, the Late Devonian sarcopterygian fish most closely related to tetrapods. Although retaining a primitive configuration in many respects, the cranial endoskeleton of T. roseae shares derived features with tetrapods such as a large basal articulation and a flat, horizontally oriented entopterygoid. Other features in T. roseae, like the short, straight hyomandibula, show morphology intermediate between the condition observed in more primitive fish and that observed in tetrapods. The combination of characters in T. roseae helps to resolve the relative timing of modifications in the cranial endoskeleton. The sequence of modifications suggests changes in head mobility and intracranial kinesis that have ramifications for the origin of vertebrate terrestriality.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Downs, Jason P -- Daeschler, Edward B -- Jenkins, Farish A Jr -- Shubin, Neil H -- England -- Nature. 2008 Oct 16;455(7215):925-9. doi: 10.1038/nature07189.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Academy of Natural Sciences of Philadelphia, 1900 Benjamin Franklin Parkway, Philadelphia, Pennsylvania 19103, USA. downs@ansp.org〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18923515" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; *Ecosystem ; Fishes/*anatomy & histology/physiology ; *Fossils ; Models, Biological ; Skull/*anatomy & histology/physiology
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  • 51
    Publication Date: 2008-03-21
    Description: In the classical model of chick wing digit-patterning, the polarizing region--a group of cells at the posterior margin of the early bud--produces a morphogen gradient, now known to be based on Sonic hedgehog (Shh), that progressively specifies anteroposterior positional identities in the posterior digit-forming region. Here we add an integral growth component to this model by showing that Shh-dependent proliferation of prospective digit progenitor cells is essential for specifying the complete pattern of digits across the anteroposterior axis. Inhibiting Shh signalling in early wing buds reduced anteroposterior expansion, and posterior digits were lost because all prospective digit precursors formed anterior structures. Inhibiting proliferation also irreversibly reduced anteroposterior expansion, but instead anterior digits were lost because all prospective digit precursors formed posterior structures. When proliferation recovered in such wings, Shh transcription was maintained for longer than normal, suggesting that duration of Shh expression is controlled by a mechanism that measures proliferation. Rescue experiments confirmed that Shh-dependent proliferation controls digit number during a discrete time-window in which Shh-dependent specification normally occurs. Our findings that Shh signalling has dual functions that can be temporally uncoupled have implications for understanding congenital and evolutionary digit reductions.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Towers, Matthew -- Mahood, Ruth -- Yin, Yili -- Tickle, Cheryll -- G9806660/Medical Research Council/United Kingdom -- England -- Nature. 2008 Apr 17;452(7189):882-6. doi: 10.1038/nature06718. Epub 2008 Mar 19.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Cell and Developmental Biology, WTB/MSI Complex, University of Dundee, Dow Street, Dundee DD1 5EH, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18354396" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Body Patterning ; Chick Embryo ; Female ; Hedgehog Proteins/metabolism ; Limb Buds/cytology/embryology ; Models, Biological ; Wings, Animal/*anatomy & histology/cytology/*embryology
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  • 52
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    Nature Publishing Group (NPG)
    Publication Date: 2008-10-31
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Abbott, Alison -- England -- Nature. 2008 Oct 30;455(7217):1164-7. doi: 10.1038/4551164a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18971993" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Clinical Trials as Topic ; *Computer Simulation ; Diabetes Mellitus, Type 2/metabolism ; Drug Industry/*methods/*trends ; Genomics ; Glycoproteins/metabolism ; Humans ; Models, Biological ; Neoplasms/metabolism ; Proteome/metabolism ; Quinazolines/pharmacology ; Systems Biology/methods/*trends
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  • 53
    Publication Date: 2008-05-02
    Description: Mitochondria use transport proteins of the eukaryotic mitochondrial carrier family (MCF) to mediate the exchange of diverse substrates, including ATP, with the host cell cytosol. According to classical endosymbiosis theory, insertion of a host-nuclear-encoded MCF transporter into the protomitochondrion was the key step that allowed the host cell to harvest ATP from the enslaved endosymbiont. Notably the genome of the microsporidian Encephalitozoon cuniculi has lost all of its genes for MCF proteins. This raises the question of how the recently discovered microsporidian remnant mitochondrion, called a mitosome, acquires ATP to support protein import and other predicted ATP-dependent activities. The E. cuniculi genome does contain four genes for an unrelated type of nucleotide transporter used by plastids and bacterial intracellular parasites, such as Rickettsia and Chlamydia, to import ATP from the cytosol of their eukaryotic host cells. The inference is that E. cuniculi also uses these proteins to steal ATP from its eukaryotic host to sustain its lifestyle as an obligate intracellular parasite. Here we show that, consistent with this hypothesis, all four E. cuniculi transporters can transport ATP, and three of them are expressed on the surface of the parasite when it is living inside host cells. The fourth transporter co-locates with mitochondrial Hsp70 to the E. cuniculi mitosome. Thus, uniquely among eukaryotes, the traditional relationship between mitochondrion and host has been subverted in E. cuniculi, by reductive evolution and analogous gene replacement. Instead of the mitosome providing the parasite cytosol with ATP, the parasite cytosol now seems to provide ATP for the organelle.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tsaousis, Anastasios D -- Kunji, Edmund R S -- Goldberg, Alina V -- Lucocq, John M -- Hirt, Robert P -- Embley, T Martin -- MC_U105663139/Medical Research Council/United Kingdom -- Medical Research Council/United Kingdom -- England -- Nature. 2008 May 22;453(7194):553-6. doi: 10.1038/nature06903. Epub 2008 Apr 30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute for Cell and Molecular Biosciences, Catherine Cookson Building, Framlington Place, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18449191" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/*metabolism ; Animals ; Biological Transport ; Carrier Proteins/genetics/immunology/metabolism ; Cell Line ; Encephalitozoon cuniculi/*cytology/genetics/*metabolism ; Escherichia coli/genetics/metabolism ; Fungal Proteins/genetics/immunology/metabolism ; Genome, Fungal/genetics ; Genome, Mitochondrial/genetics ; Mitochondria/genetics/*metabolism ; Models, Biological ; Molecular Sequence Data ; Rabbits ; Rats ; Symbiosis
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  • 54
    Publication Date: 2008-10-17
    Description: Over 30% of proteins are secreted across or integrated into membranes. Their newly synthesized forms contain either cleavable signal sequences or non-cleavable membrane anchor sequences, which direct them to the evolutionarily conserved Sec translocon (SecYEG in prokaryotes and Sec61, comprising alpha-, gamma- and beta-subunits, in eukaryotes). The translocon then functions as a protein-conducting channel. These processes of protein localization occur either at or after translation. In bacteria, the SecA ATPase drives post-translational translocation. The only high-resolution structure of a translocon available so far is that for SecYEbeta from the archaeon Methanococcus jannaschii, which lacks SecA. Here we present the 3.2-A-resolution crystal structure of the SecYE translocon from a SecA-containing organism, Thermus thermophilus. The structure, solved as a complex with an anti-SecY Fab fragment, revealed a 'pre-open' state of SecYE, in which several transmembrane helices are shifted, as compared to the previous SecYEbeta structure, to create a hydrophobic crack open to the cytoplasm. Fab and SecA bind to a common site at the tip of the cytoplasmic domain of SecY. Molecular dynamics and disulphide mapping analyses suggest that the pre-open state might represent a SecYE conformational transition that is inducible by SecA binding. Moreover, we identified a SecA-SecYE interface that comprises SecA residues originally buried inside the protein, indicating that both the channel and the motor components of the Sec machinery undergo cooperative conformational changes on formation of the functional complex.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2590585/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2590585/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tsukazaki, Tomoya -- Mori, Hiroyuki -- Fukai, Shuya -- Ishitani, Ryuichiro -- Mori, Takaharu -- Dohmae, Naoshi -- Perederina, Anna -- Sugita, Yuji -- Vassylyev, Dmitry G -- Ito, Koreaki -- Nureki, Osamu -- R01 GM074252/GM/NIGMS NIH HHS/ -- R01 GM074252-04/GM/NIGMS NIH HHS/ -- R01 GM074840/GM/NIGMS NIH HHS/ -- R01 GM074840-04/GM/NIGMS NIH HHS/ -- England -- Nature. 2008 Oct 16;455(7215):988-91. doi: 10.1038/nature07421.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama-shi, Kanagawa 226-8501, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18923527" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Proteins/*chemistry/genetics/immunology/*metabolism ; Binding Sites ; Crystallography, X-Ray ; Disulfides/chemistry/metabolism ; Hydrophobic and Hydrophilic Interactions ; Immunoglobulin Fab Fragments/chemistry/immunology ; Methanococcus/chemistry/enzymology ; Models, Biological ; Models, Molecular ; Protein Binding ; Protein Structure, Tertiary ; Thermus thermophilus/*chemistry/*enzymology/genetics
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  • 55
    Publication Date: 2008-05-30
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schall, Jos J -- England -- Nature. 2008 May 29;453(7195):605-6. doi: 10.1038/453605a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18509433" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; Female ; Fertility/genetics/physiology ; Humans ; Malaria/*parasitology ; Male ; Models, Biological ; Plasmodium chabaudi/genetics/*physiology ; *Sex Ratio
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  • 56
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    Nature Publishing Group (NPG)
    Publication Date: 2008-05-24
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Haugh, Jason M -- England -- Nature. 2008 May 22;453(7194):461-2. doi: 10.1038/453461a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18497809" target="_blank"〉PubMed〈/a〉
    Keywords: Actin Cytoskeleton/chemistry/metabolism ; Animals ; Cell Movement/*physiology ; Cell Shape/*physiology ; Epithelial Cells/*cytology ; Fishes ; Models, Biological
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  • 57
    Publication Date: 2008-09-27
    Description: Opsin, the ligand-free form of the G-protein-coupled receptor rhodopsin, at low pH adopts a conformationally distinct, active G-protein-binding state known as Ops*. A synthetic peptide derived from the main binding site of the heterotrimeric G protein-the carboxy terminus of the alpha-subunit (GalphaCT)-stabilizes Ops*. Here we present the 3.2 A crystal structure of the bovine Ops*-GalphaCT peptide complex. GalphaCT binds to a site in opsin that is opened by an outward tilt of transmembrane helix (TM) 6, a pairing of TM5 and TM6, and a restructured TM7-helix 8 kink. Contacts along the inner surface of TM5 and TM6 induce an alpha-helical conformation in GalphaCT with a C-terminal reverse turn. Main-chain carbonyl groups in the reverse turn constitute the centre of a hydrogen-bonded network, which links the two receptor regions containing the conserved E(D)RY and NPxxY(x)(5,6)F motifs. On the basis of the Ops*-GalphaCT structure and known conformational changes in Galpha, we discuss signal transfer from the receptor to the G protein nucleotide-binding site.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Scheerer, Patrick -- Park, Jung Hee -- Hildebrand, Peter W -- Kim, Yong Ju -- Krauss, Norbert -- Choe, Hui-Woog -- Hofmann, Klaus Peter -- Ernst, Oliver P -- England -- Nature. 2008 Sep 25;455(7212):497-502. doi: 10.1038/nature07330.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut fur Medizinische Physik und Biophysik (CC2), Charite - Universitatsmedizin Berlin, Chariteplatz 1, D-10117 Berlin, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18818650" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Motifs ; Animals ; Arginine/chemistry/metabolism ; Binding Sites ; Cattle ; Conserved Sequence ; Crystallization ; Crystallography, X-Ray ; GTP-Binding Protein alpha Subunits/*chemistry/*metabolism ; Models, Biological ; Models, Molecular ; Protein Conformation ; Regeneration ; Retinaldehyde/chemistry/metabolism ; Rhodopsin/chemistry ; Rod Opsins/*chemistry/*metabolism ; Signal Transduction
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  • 58
    Publication Date: 2008-05-10
    Description: Despite two centuries of effort in characterizing environmental gradients of species richness in search of universal patterns, surprisingly few of these patterns have been widely acknowledged. Species richness along altitudinal gradients was previously assumed to increase universally from cool highlands to warm lowlands, mirroring the latitudinal increase in species richness from cool to warm latitudes. However, since the more recent general acceptance of altitudinal gradients as model templates for testing hypotheses behind large-scale patterns of diversity, these gradients have been used in support of all the main diversity hypotheses, although little consensus has been achieved. Here we show that when resampling a data set comprising 400,000 records for 3,046 Pyrenean floristic species at different scales of analysis (achieved by varying grain size and the extent of the gradients sampled), the derived species richness pattern changed progressively from hump-shaped to a monotonic pattern as the scale of extent diminished. Scale effects alone gave rise to as many conflicting patterns of species richness as had previously been reported in the literature, and scale effects lent significantly different statistical support to competing diversity hypotheses. Effects of scale on current studies may be affected by human activities, because montane ecosystems and human activities are intimately connected. This interdependence has led to a global reduction in natural lowland habitats, hampering our ability to detect universal patterns and impeding the search for universal diversity gradients to discover the mechanisms determining the distribution of biological diversity on Earth.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nogues-Bravo, D -- Araujo, M B -- Romdal, T -- Rahbek, C -- England -- Nature. 2008 May 8;453(7192):216-9. doi: 10.1038/nature06812.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biodiversity and Evolutionary Biology, National Museum of Natural Sciences, CSIC, C/ Jose Gutierrez Abascal, 2, 28006 Madrid, Spain. davidnogues@mncn.csic.es〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18464741" target="_blank"〉PubMed〈/a〉
    Keywords: *Altitude ; *Biodiversity ; Computer Simulation ; Costa Rica ; *Human Activities ; Models, Biological ; Software ; Spain ; Trees/physiology ; Tropical Climate
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  • 59
    Publication Date: 2008-10-17
    Description: An important step in the biosynthesis of many proteins is their partial or complete translocation across the plasma membrane in prokaryotes or the endoplasmic reticulum membrane in eukaryotes. In bacteria, secretory proteins are generally translocated after completion of their synthesis by the interaction of the cytoplasmic ATPase SecA and a protein-conducting channel formed by the SecY complex. How SecA moves substrates through the SecY channel is unclear. However, a recent structure of a SecA-SecY complex raises the possibility that the polypeptide chain is moved by a two-helix finger domain of SecA that is inserted into the cytoplasmic opening of the SecY channel. Here we have used disulphide-bridge crosslinking to show that the loop at the tip of the two-helix finger of Escherichia coli SecA interacts with a polypeptide chain right at the entrance into the SecY pore. Mutagenesis demonstrates that a tyrosine in the loop is particularly important for translocation, but can be replaced by some other bulky, hydrophobic residues. We propose that the two-helix finger of SecA moves a polypeptide chain into the SecY channel with the tyrosine providing the major contact with the substrate, a mechanism analogous to that suggested for hexameric, protein-translocating ATPases.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4354775/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4354775/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Erlandson, Karl J -- Miller, Stephanie B M -- Nam, Yunsun -- Osborne, Andrew R -- Zimmer, Jochen -- Rapoport, Tom A -- R01 GM052586/GM/NIGMS NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2008 Oct 16;455(7215):984-7. doi: 10.1038/nature07439.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18923526" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphatases/*chemistry/genetics/*metabolism ; Amino Acid Motifs ; Bacterial Proteins/*chemistry/genetics/*metabolism ; Cross-Linking Reagents ; Disulfides/chemistry/metabolism ; Escherichia coli/*enzymology ; Escherichia coli Proteins/chemistry/metabolism ; Membrane Transport Proteins/*chemistry/genetics/*metabolism ; Models, Biological ; Models, Molecular ; Protein Conformation ; Protein Transport ; Structure-Activity Relationship ; Tyrosine/metabolism
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  • 60
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    Unknown
    Nature Publishing Group (NPG)
    Publication Date: 2008-07-25
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nurse, Paul -- England -- Nature. 2008 Jul 24;454(7203):424-6. doi: 10.1038/454424a.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Rockefeller University, 1230 York Avenue, New York, New York 10065, USA. nurse@mail.rockefeller.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18650911" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biological Science Disciplines/education/*methods/trends ; Humans ; *Information Science/methods/trends ; *Logic ; Models, Biological
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  • 61
    Publication Date: 2008-05-16
    Description: Epithelial tissues maintain a robust architecture which is important for their barrier function, but they are also remodelled through the reorganization of cell-cell contacts. Tissue stability requires intercellular adhesion mediated by E-cadherin, in particular its trans-association in homophilic complexes supported by actin filaments through beta- and alpha-catenin. How alpha-catenin dynamic interactions between E-cadherin/beta-catenin and cortical actin control both stability and remodelling of adhesion is unclear. Here we focus on Drosophila homophilic E-cadherin complexes rather than total E-cadherin, including diffusing 'free' E-cadherin, because these complexes are a better proxy for adhesion. We find that E-cadherin complexes partition in very stable microdomains (that is, bona fide adhesive foci which are more stable than remodelling contacts). Furthermore, we find that stability and mobility of these microdomains depend on two actin populations: small, stable actin patches concentrate at homophilic E-cadherin clusters, whereas a rapidly turning over, contractile network constrains their lateral movement by a tethering mechanism. alpha-Catenin controls epithelial architecture mainly through regulation of the mobility of homophilic clusters and it is largely dispensable for their stability. Uncoupling stability and mobility of E-cadherin complexes suggests that stable epithelia may remodel through the regulated mobility of very stable adhesive foci.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cavey, Matthieu -- Rauzi, Matteo -- Lenne, Pierre-Francois -- Lecuit, Thomas -- England -- Nature. 2008 Jun 5;453(7196):751-6. doi: 10.1038/nature06953. Epub 2008 May 14.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institut de Biologie du Developpment de Marseille Luminy, UMR 6216 CNRS-Universite de la Mediterranee, Campus de Luminy case 907, 13288 Marseille Cedex 09, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18480755" target="_blank"〉PubMed〈/a〉
    Keywords: Actins/metabolism ; Animals ; Cadherins/chemistry/*metabolism ; Cell Adhesion ; Drosophila melanogaster/embryology/genetics/*metabolism ; Epithelium/*metabolism ; Female ; Male ; Models, Biological ; alpha Catenin/genetics/metabolism
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  • 62
    Publication Date: 2008-08-16
    Description: Diverse cell polarity networks require positive feedback for locally amplifying distributions of signalling molecules at the plasma membrane. Additional mechanisms, such as directed transport or coupled inhibitors, have been proposed to be required for reinforcing a unique axis of polarity. Here we analyse a simple model of positive feedback, with strong analogy to the 'stepping stone' model of population genetics, in which a single species of diffusible, membrane-bound signalling molecules can self-recruit from a cytoplasmic pool. We identify an intrinsic stochastic mechanism through which positive feedback alone is sufficient to account for the spontaneous establishment of a single site of polarity. We find that the polarization frequency has an inverse dependence on the number of signalling molecules: the frequency of polarization decreases as the number of molecules becomes large. Experimental observation of polarizing Cdc42 in budding yeast is consistent with this prediction. Our work suggests that positive feedback can work alone or with additional mechanisms to create robust cell polarity.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2562338/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2562338/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Altschuler, Steven J -- Angenent, Sigurd B -- Wang, Yanqin -- Wu, Lani F -- R01 GM071794/GM/NIGMS NIH HHS/ -- R01 GM071794-05/GM/NIGMS NIH HHS/ -- England -- Nature. 2008 Aug 14;454(7206):886-9. doi: 10.1038/nature07119.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Green Center for Systems Biology, Department of Pharmacology and Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA. steven.altschuler@utsouthwestern.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18704086" target="_blank"〉PubMed〈/a〉
    Keywords: Cell Polarity/*physiology ; Computer Simulation ; Feedback, Physiological ; Models, Biological ; Models, Molecular ; Saccharomyces cerevisiae/*cytology/*metabolism ; Signal Transduction ; cdc42 GTP-Binding Protein, Saccharomyces cerevisiae/*metabolism
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  • 63
    Publication Date: 2008-09-23
    Description: Most bilaterian animals possess a through gut with a separate mouth and anus. It is commonly believed that during the transition from radial to bilateral symmetry, both openings evolved simultaneously by the lateral closure of a slit-like blastopore. Molecular phylogenies however, place the acoel flatworms, which have only one opening to their digestive system, as the sister group to all remaining Bilateria. To address how this single body opening is related to the mouth and anus of the protostomes and deuterostomes, we studied the expression of genes involved in bilaterian foregut and hindgut patterning during the development of the acoel Convolutriloba longifissura. Here we show that the genes brachyury and goosecoid are expressed in association with the acoel mouth, suggesting that this single opening is homologous to the mouth of other bilaterians. In addition, we find that the genes caudal, orthopedia and brachyury-which are expressed in various bilaterian hindguts-are expressed in a small region at the posterior end of the animal, separated from the anterior oral brachyury-expressing region by a dorsal domain of ectodermal bmp2/4 expression. These results contradict the hypothesis that the bilaterian mouth and anus evolved simultaneously from a common blastoporal opening, and suggest that a through gut might have evolved independently in different animal lineages.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hejnol, Andreas -- Martindale, Mark Q -- England -- Nature. 2008 Nov 20;456(7220):382-6. doi: 10.1038/nature07309. Epub 2008 Sep 17.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Kewalo Marine Laboratory, PBRC, University of Hawaii, 41 Ahui Street, Honolulu, Hawaii 96813, USA. hejnol@hawaii.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18806777" target="_blank"〉PubMed〈/a〉
    Keywords: Anal Canal/*anatomy & histology/*embryology/growth & development ; Animals ; *Biological Evolution ; Gene Expression Regulation, Developmental ; Genes, Helminth/genetics ; Models, Biological ; Mouth/*anatomy & histology/*embryology/growth & development ; Turbellaria/*anatomy & histology/*embryology/genetics/growth & development
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  • 64
    Publication Date: 2008-06-13
    Description: The oxygen isotope ratio (delta(18)O) of cellulose is thought to provide a record of ambient temperature and relative humidity during periods of carbon assimilation. Here we introduce a method to resolve tree-canopy leaf temperature with the use of delta(18)O of cellulose in 39 tree species. We show a remarkably constant leaf temperature of 21.4 +/- 2.2 degrees C across 50 degrees of latitude, from subtropical to boreal biomes. This means that when carbon assimilation is maximal, the physiological and morphological properties of tree branches serve to raise leaf temperature above air temperature to a much greater extent in more northern latitudes. A main assumption underlying the use of delta(18)O to reconstruct climate history is that the temperature and relative humidity of an actively photosynthesizing leaf are the same as those of the surrounding air. Our data are contrary to that assumption and show that plant physiological ecology must be considered when reconstructing climate through isotope analysis. Furthermore, our results may explain why climate has only a modest effect on leaf economic traits in general.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Helliker, Brent R -- Richter, Suzanna L -- England -- Nature. 2008 Jul 24;454(7203):511-4. doi: 10.1038/nature07031. Epub 2008 Jun 11.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. helliker@sas.upenn.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18548005" target="_blank"〉PubMed〈/a〉
    Keywords: Caribbean Region ; Cellulose/chemistry/metabolism ; *Climate ; Humidity ; Models, Biological ; North America ; Oxygen Isotopes ; *Plant Leaves/physiology ; *Temperature ; *Trees/physiology ; Tropical Climate
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  • 65
    Publication Date: 2008-05-24
    Description: The origin of extant amphibians (Lissamphibia: frogs, salamanders and caecilians) is one of the most controversial questions in vertebrate evolution, owing to large morphological and temporal gaps in the fossil record. Current discussions focus on three competing hypotheses: a monophyletic origin within either Temnospondyli or Lepospondyli, or a polyphyletic origin with frogs and salamanders arising among temnospondyls and caecilians among the lepospondyls. Recent molecular analyses are also controversial, with estimations for the batrachian (frog-salamander) divergence significantly older than the palaeontological evidence supports. Here we report the discovery of an amphibamid temnospondyl from the Early Permian of Texas that bridges the gap between other Palaeozoic amphibians and the earliest known salientians and caudatans from the Mesozoic. The presence of a mosaic of salientian and caudatan characters in this small fossil makes it a key taxon close to the batrachian (frog and salamander) divergence. Phylogenetic analysis suggests that the batrachian divergence occurred in the Middle Permian, rather than the late Carboniferous as recently estimated using molecular clocks, but the divergence with caecilians corresponds to the deep split between temnospondyls and lepospondyls, which is congruent with the molecular estimates.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Anderson, Jason S -- Reisz, Robert R -- Scott, Diane -- Frobisch, Nadia B -- Sumida, Stuart S -- England -- Nature. 2008 May 22;453(7194):515-8. doi: 10.1038/nature06865.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, 3330 Hospital Drive, Calgary, Alberta T2N 4N1, Canada. janders@ucalgary.ca〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18497824" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Anura/anatomy & histology ; *Fossils ; Models, Biological ; *Phylogeny ; Skull/anatomy & histology ; Texas ; *Urodela/anatomy & histology
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  • 66
    Publication Date: 2008-03-14
    Description: Positive relationships between species diversity and productivity have been reported for a number of ecosystems. Theoretical and experimental studies have attempted to determine the mechanisms that generate this pattern over short timescales, but little attention has been given to the problem of understanding how diversity and productivity are linked over evolutionary timescales. Here, we investigate the role of dispersal in determining both diversity and productivity over evolutionary timescales, using experimental metacommunities of the bacterium Pseudomonas fluorescens assembled by divergent natural selection. We show that both regional diversity and productivity peak at an intermediate dispersal rate. Moreover, we demonstrate that these two patterns are linked: selection at intermediate rates of dispersal leads to high niche differentiation between genotypes, allowing greater coverage of the heterogeneous environment and a higher regional productivity. We argue that processes that operate over both ecological and evolutionary timescales should be jointly considered when attempting to understand the emergence of ecosystem-level properties such as diversity-function relationships.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Venail, P A -- MacLean, R C -- Bouvier, T -- Brockhurst, M A -- Hochberg, M E -- Mouquet, N -- England -- Nature. 2008 Mar 13;452(7184):210-4. doi: 10.1038/nature06554.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Universite Montpellier 2, CNRS, UMR 5554 Institut des Sciences de l'Evolution, CC065 Place Eugene Bataillon, Montpellier cedex 05, France. pvenail@univ-montp2.fr〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18337821" target="_blank"〉PubMed〈/a〉
    Keywords: *Biodiversity ; *Biological Evolution ; *Ecosystem ; Genotype ; Models, Biological ; Phenotype ; Pseudomonas fluorescens/*genetics/*physiology ; *Selection, Genetic
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  • 67
    Publication Date: 2008-09-06
    Description: DNA methylation of CpG dinucleotides is an important epigenetic modification of mammalian genomes and is essential for the regulation of chromatin structure, of gene expression and of genome stability. Differences in DNA methylation patterns underlie a wide range of biological processes, such as genomic imprinting, inactivation of the X chromosome, embryogenesis, and carcinogenesis. Inheritance of the epigenetic methylation pattern is mediated by the enzyme DNA methyltransferase 1 (Dnmt1), which methylates newly synthesized CpG sequences during DNA replication, depending on the methylation status of the template strands. The protein UHRF1 (also known as Np95 and ICBP90) recognizes hemi-methylation sites via a SET and RING-associated (SRA) domain and directs Dnmt1 to these sites. Here we report the crystal structures of the SRA domain in free and hemi-methylated DNA-bound states. The SRA domain folds into a globular structure with a basic concave surface formed by highly conserved residues. Binding of DNA to the concave surface causes a loop and an amino-terminal tail of the SRA domain to fold into DNA interfaces at the major and minor grooves of the methylation site. In contrast to fully methylated CpG sites recognized by the methyl-CpG-binding domain, the methylcytosine base at the hemi-methylated site is flipped out of the DNA helix in the SRA-DNA complex and fits tightly into a protein pocket on the concave surface. The complex structure suggests that the successive flip out of the pre-existing methylated cytosine and the target cytosine to be methylated is associated with the coordinated transfer of the hemi-methylated CpG site from UHRF1 to Dnmt1.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Arita, Kyohei -- Ariyoshi, Mariko -- Tochio, Hidehito -- Nakamura, Yusuke -- Shirakawa, Masahiro -- England -- Nature. 2008 Oct 9;455(7214):818-21. doi: 10.1038/nature07249. Epub 2008 Sep 3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18772891" target="_blank"〉PubMed〈/a〉
    Keywords: 5-Methylcytosine/metabolism ; Animals ; Base Sequence ; Conserved Sequence ; CpG Islands/genetics ; Crystallography, X-Ray ; DNA/*chemistry/genetics/*metabolism ; DNA (Cytosine-5-)-Methyltransferase/metabolism ; *DNA Methylation ; Mice ; Models, Biological ; Models, Molecular ; Molecular Conformation ; Nuclear Proteins/*chemistry/*metabolism ; Protein Binding ; Protein Structure, Tertiary
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  • 68
    Publication Date: 2008-04-11
    Description: During haematopoiesis, pluripotent haematopoietic stem cells are sequentially restricted to give rise to a variety of lineage-committed progenitors. The classical model of haematopoiesis postulates that, in the first step of differentiation, the stem cell generates common myelo-erythroid progenitors and common lymphoid progenitors (CLPs). However, our previous studies in fetal mice showed that myeloid potential persists even as the lineage branches segregate towards T and B cells. We therefore proposed the 'myeloid-based' model of haematopoiesis, in which the stem cell initially generates common myelo-erythroid progenitors and common myelo-lymphoid progenitors. T-cell and B-cell progenitors subsequently arise from common myelo-lymphoid progenitors through myeloid-T and myeloid-B stages, respectively. However, it has been unclear whether this myeloid-based model is also valid for adult haematopoiesis. Here we provide clonal evidence that the early cell populations in the adult thymus contain progenitors that have lost the potential to generate B cells but retain substantial macrophage potential as well as T-cell, natural killer (NK)-cell and dendritic-cell potential. We also show that such T-cell progenitors can give rise to macrophages in the thymic environment in vivo. Our findings argue against the classical dichotomy model in which T cells are derived from CLPs; instead, they support the validity of the myeloid-based model for both adult and fetal haematopoiesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wada, Haruka -- Masuda, Kyoko -- Satoh, Rumi -- Kakugawa, Kiyokazu -- Ikawa, Tomokatsu -- Katsura, Yoshimoto -- Kawamoto, Hiroshi -- England -- Nature. 2008 Apr 10;452(7188):768-72. doi: 10.1038/nature06839.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory for Lymphocyte Development, RIKEN Research Center for Allergy and Immunology, Yokohama 230-0045, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18401412" target="_blank"〉PubMed〈/a〉
    Keywords: Aging/*physiology ; Animals ; B-Lymphocytes/cytology ; *Cell Lineage ; Cells, Cultured ; Coculture Techniques ; Dendritic Cells/cytology ; Fetus ; *Hematopoiesis ; Hematopoietic Stem Cells/*cytology/metabolism ; Killer Cells, Natural/cytology ; Macrophages/cytology/metabolism ; Mice ; Models, Biological ; Myeloid Cells/*cytology/metabolism ; Stromal Cells/cytology ; T-Lymphocytes/*cytology/metabolism ; Thymus Gland/cytology/embryology/transplantation
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  • 69
    Publication Date: 2008-06-20
    Description: Dinitrogen (N(2)) fixation is widely recognized as an important process in controlling ecosystem responses to global environmental change, both today and in the past; however, significant discrepancies exist between theory and observations of patterns of N(2) fixation across major sectors of the land biosphere. A question remains as to why symbiotic N(2)-fixing plants are more abundant in vast areas of the tropics than in many of the mature forests that seem to be nitrogen-limited in the temperate and boreal zones. Here we present a unifying framework for terrestrial N(2) fixation that can explain the geographic occurrence of N(2) fixers across diverse biomes and at the global scale. By examining trade-offs inherent in plant carbon, nitrogen and phosphorus capture, we find a clear advantage to symbiotic N(2) fixers in phosphorus-limited tropical savannas and lowland tropical forests. The ability of N(2) fixers to invest nitrogen into phosphorus acquisition seems vital to sustained N(2) fixation in phosphorus-limited tropical ecosystems. In contrast, modern-day temperatures seem to constrain N(2) fixation rates and N(2)-fixing species from mature forests in the high latitudes. We propose that an analysis that couples biogeochemical cycling and biophysical mechanisms is sufficient to explain the principal geographical patterns of symbiotic N(2) fixation on land, thus providing a basis for predicting the response of nutrient-limited ecosystems to climate change and increasing atmospheric CO(2).〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Houlton, Benjamin Z -- Wang, Ying-Ping -- Vitousek, Peter M -- Field, Christopher B -- England -- Nature. 2008 Jul 17;454(7202):327-30. doi: 10.1038/nature07028. Epub 2008 Jun 18.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Biological Sciences, Stanford University, Stanford, California 94305, USA. bzhoulton@ucdavis.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18563086" target="_blank"〉PubMed〈/a〉
    Keywords: *Ecosystem ; Models, Biological ; *Nitrogen Fixation ; Nitrogenase/metabolism ; Phosphates/metabolism ; Phosphoric Monoester Hydrolases/metabolism ; Plants/enzymology/*metabolism ; Soil/analysis ; Symbiosis ; Temperature ; Tropical Climate
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  • 70
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    Unknown
    Nature Publishing Group (NPG)
    Publication Date: 2009-06-19
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Reiff, Sarah B -- Striepen, Boris -- England -- Nature. 2009 Jun 18;459(7249):918-9. doi: 10.1038/459918a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19536248" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Humans ; Malaria, Falciparum/drug therapy/*parasitology ; Models, Biological ; Plasmodium falciparum/*metabolism ; Protein Binding ; Protein Transport ; Protozoan Proteins/antagonists & inhibitors/*metabolism ; Vacuoles/metabolism/parasitology
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  • 71
    Publication Date: 2009-12-18
    Description: An important challenge in systems biology is to quantitatively describe microbial growth using a few measurable parameters that capture the essence of this complex phenomenon. Two key events at the cell membrane-extracellular glucose sensing and uptake-initiate the budding yeast's growth on glucose. However, conventional growth models focus almost exclusively on glucose uptake. Here we present results from growth-rate experiments that cannot be explained by focusing on glucose uptake alone. By imposing a glucose uptake rate independent of the sensed extracellular glucose level, we show that despite increasing both the sensed glucose concentration and uptake rate, the cell's growth rate can decrease or even approach zero. We resolve this puzzle by showing that the interaction between glucose perception and import, not their individual actions, determines the central features of growth, and characterize this interaction using a quantitative model. Disrupting this interaction by knocking out two key glucose sensors significantly changes the cell's growth rate, yet uptake rates are unchanged. This is due to a decrease in burden that glucose perception places on the cells. Our work shows that glucose perception and import are separate and pivotal modules of yeast growth, the interaction of which can be precisely tuned and measured.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2796206/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2796206/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Youk, Hyun -- van Oudenaarden, Alexander -- DP1 OD003936/OD/NIH HHS/ -- DP1 OD003936-01/OD/NIH HHS/ -- DP1 OD003936-02/OD/NIH HHS/ -- R01 GM068957/GM/NIGMS NIH HHS/ -- R01 GM068957-06/GM/NIGMS NIH HHS/ -- R01 GM068957-07/GM/NIGMS NIH HHS/ -- England -- Nature. 2009 Dec 17;462(7275):875-9. doi: 10.1038/nature08653.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20016593" target="_blank"〉PubMed〈/a〉
    Keywords: Biological Transport/drug effects ; Cell Growth Processes/drug effects ; Cell Membrane/drug effects/metabolism ; Doxycycline/pharmacology ; Glucose/*metabolism/pharmacology ; Kinetics ; Models, Biological ; Saccharomyces cerevisiae/cytology/drug effects/*growth & development/*metabolism
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  • 72
    Publication Date: 2009-09-11
    Description: It is widely accepted that tissue differentiation and morphogenesis in multicellular organisms are regulated by tightly controlled concentration gradients of morphogens. How exactly these gradients are formed, however, remains unclear. Here we show that Fgf8 morphogen gradients in living zebrafish embryos are established and maintained by two essential factors: fast, free diffusion of single molecules away from the source through extracellular space, and a sink function of the receiving cells, regulated by receptor-mediated endocytosis. Evidence is provided by directly examining single molecules of Fgf8 in living tissue by fluorescence correlation spectroscopy, quantifying their local mobility and concentration with high precision. By changing the degree of uptake of Fgf8 into its target cells, we are able to alter the shape of the Fgf8 gradient. Our results demonstrate that a freely diffusing morphogen can set up concentration gradients in a complex multicellular tissue by a simple source-sink mechanism.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Yu, Shuizi Rachel -- Burkhardt, Markus -- Nowak, Matthias -- Ries, Jonas -- Petrasek, Zdenek -- Scholpp, Steffen -- Schwille, Petra -- Brand, Michael -- England -- Nature. 2009 Sep 24;461(7263):533-6. doi: 10.1038/nature08391. Epub 2009 Sep 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Developmental Genetics, Biotechnology Center, TUD, Tatzberg 47-49, 01307 Dresden, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19741606" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Diffusion ; Embryo, Nonmammalian/*cytology/embryology/*metabolism ; *Endocytosis ; Extracellular Space/metabolism ; Fibroblast Growth Factors/genetics/*metabolism ; Gastrulation ; Green Fluorescent Proteins/genetics/metabolism ; Models, Biological ; Morphogenesis/*physiology ; Receptors, Fibroblast Growth Factor/metabolism ; Zebrafish/*embryology/*metabolism ; Zebrafish Proteins/genetics/*metabolism
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  • 73
    Publication Date: 2009-06-19
    Description: Several hundred malaria parasite proteins are exported beyond an encasing vacuole and into the cytosol of the host erythrocyte, a process that is central to the virulence and viability of the causative Plasmodium species. The trafficking machinery responsible for this export is unknown. Here we identify in Plasmodium falciparum a translocon of exported proteins (PTEX), which is located in the vacuole membrane. The PTEX complex is ATP-powered, and comprises heat shock protein 101 (HSP101; a ClpA/B-like ATPase from the AAA+ superfamily, of a type commonly associated with protein translocons), a novel protein termed PTEX150 and a known parasite protein, exported protein 2 (EXP2). EXP2 is the potential channel, as it is the membrane-associated component of the core PTEX complex. Two other proteins, a new protein PTEX88 and thioredoxin 2 (TRX2), were also identified as PTEX components. As a common portal for numerous crucial processes, this translocon offers a new avenue for therapeutic intervention.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2725363/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2725363/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉de Koning-Ward, Tania F -- Gilson, Paul R -- Boddey, Justin A -- Rug, Melanie -- Smith, Brian J -- Papenfuss, Anthony T -- Sanders, Paul R -- Lundie, Rachel J -- Maier, Alexander G -- Cowman, Alan F -- Crabb, Brendan S -- R01 AI044008-11/AI/NIAID NIH HHS/ -- R01 AI44008/AI/NIAID NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2009 Jun 18;459(7249):945-9. doi: 10.1038/nature08104.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Walter & Eliza Hall Institute of Medical Research, Melbourne 3052, Australia.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19536257" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Animals, Genetically Modified ; Malaria, Falciparum/*parasitology ; Models, Biological ; Multiprotein Complexes/*chemistry/*metabolism ; Plasmodium falciparum/*metabolism ; Protein Binding ; Protein Transport ; Protozoan Proteins/*metabolism
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  • 74
    Publication Date: 2009-07-17
    Description: In recent years, strikingly consistent patterns of biodiversity have been identified over space, time, organism type and geographical region. A neutral theory (assuming no environmental selection or organismal interactions) has been shown to predict many patterns of ecological biodiversity. This theory is based on a mechanism by which new species arise similarly to point mutations in a population without sexual reproduction. Here we report the simulation of populations with sexual reproduction, mutation and dispersal. We found simulated time dependence of speciation rates, species-area relationships and species abundance distributions consistent with the behaviours found in nature. From our results, we predict steady speciation rates, more species in one-dimensional environments than two-dimensional environments, three scaling regimes of species-area relationships and lognormal distributions of species abundance with an excess of rare species and a tail that may be approximated by Fisher's logarithmic series. These are consistent with dependences reported for, among others, global birds and flowering plants, marine invertebrate fossils, ray-finned fishes, British birds and moths, North American songbirds, mammal fossils from Kansas and Panamanian shrubs. Quantitative comparisons of specific cases are remarkably successful. Our biodiversity results provide additional evidence that species diversity arises without specific physical barriers. This is similar to heavy traffic flows, where traffic jams can form even without accidents or barriers.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉de Aguiar, M A M -- Baranger, M -- Baptestini, E M -- Kaufman, L -- Bar-Yam, Y -- England -- Nature. 2009 Jul 16;460(7253):384-7. doi: 10.1038/nature08168.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉New England Complex Systems Institute, Cambridge, Massachusetts 02138, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19606148" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biodiversity ; Disorders of Sex Development ; Extinction, Biological ; *Genetic Speciation ; Genotype ; Haploidy ; Models, Biological ; Mutation/genetics ; Population Dynamics ; Reproduction/genetics/*physiology ; Sexual Behavior, Animal ; Time Factors
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  • 75
    Publication Date: 2009-01-17
    Description: Autonomous and self-sustained oscillator circuits mediating the periodic induction of specific target genes are minimal genetic time-keeping devices found in the central and peripheral circadian clocks. They have attracted significant attention because of their intriguing dynamics and their importance in controlling critical repair, metabolic and signalling pathways. The precise molecular mechanism and expression dynamics of this mammalian circadian clock are still not fully understood. Here we describe a synthetic mammalian oscillator based on an auto-regulated sense-antisense transcription control circuit encoding a positive and a time-delayed negative feedback loop, enabling autonomous, self-sustained and tunable oscillatory gene expression. After detailed systems design with experimental analyses and mathematical modelling, we monitored oscillating concentrations of green fluorescent protein with tunable frequency and amplitude by time-lapse microscopy in real time in individual Chinese hamster ovary cells. The synthetic mammalian clock may provide an insight into the dynamics of natural periodic processes and foster advances in the design of prosthetic networks in future gene and cell therapies.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tigges, Marcel -- Marquez-Lago, Tatiana T -- Stelling, Jorg -- Fussenegger, Martin -- England -- Nature. 2009 Jan 15;457(7227):309-12. doi: 10.1038/nature07616.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, CH-4058 Basel, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19148099" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biological Clocks/*physiology ; CHO Cells ; Circadian Rhythm/*physiology ; Cricetinae ; Cricetulus ; Feedback, Physiological ; Fluorescence ; Gene Expression Regulation/*genetics ; Genes, Synthetic/*genetics ; *Genetic Engineering ; Green Fluorescent Proteins/analysis/genetics/metabolism ; Models, Biological ; Reproducibility of Results ; Time Factors ; Transcription, Genetic
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  • 76
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    Nature Publishing Group (NPG)
    Publication Date: 2009-11-06
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Todes, Daniel -- England -- Nature. 2009 Nov 5;462(7269):36-7. doi: 10.1038/462036a.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of the History of Medicine at Johns Hopkins University, 1900 East Monument Street, Baltimore, Maryland 21205, USA. dtodes@jhmi.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19890312" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; Biological Science Disciplines/*history ; *Competitive Behavior ; Cooperative Behavior ; *Cultural Diversity ; Food Supply ; Great Britain ; History, 19th Century ; History, 20th Century ; Humans ; Literature, Modern/history ; Metaphor ; Models, Biological ; Population Density ; Russia ; Selection, Genetic
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  • 77
    Publication Date: 2009-04-17
    Description: During cell division microtubules capture chromosomes by binding to the kinetochore assembled in the centromeric region of chromosomes. In mitosis sister chromatids are captured by microtubules emanating from both spindle poles, a process called bipolar attachment, whereas in meiosis I sisters are attached to microtubules originating from one spindle pole, called monopolar attachment. For determining chromosome orientation, kinetochore geometry or structure might be an important target of regulation. However, the molecular basis of this regulation has remained elusive. Here we show the link between kinetochore orientation and cohesion within the centromere in fission yeast Schizosaccharomyces pombe by strategies developed to visualize the concealed cohesion within the centromere, and to introduce artificial tethers that can influence kinetochore geometry. Our data imply that cohesion at the core centromere induces the mono-orientation of kinetochores whereas cohesion at the peri-centromeric region promotes bi-orientation. Our study may reveal a general mechanism for the geometric regulation of kinetochores, which collaborates with previously defined tension-dependent reorientation machinery.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sakuno, Takeshi -- Tada, Kenji -- Watanabe, Yoshinori -- England -- Nature. 2009 Apr 16;458(7240):852-8. doi: 10.1038/nature07876.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, Yayoi, Tokyo 113-0032, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19370027" target="_blank"〉PubMed〈/a〉
    Keywords: Centromere/genetics/*metabolism ; Chromosome Segregation ; Kinetochores/*metabolism ; Meiosis ; Microtubules/metabolism ; Mitosis ; Models, Biological ; Schizosaccharomyces/*cytology
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  • 78
    Publication Date: 2009-01-23
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Abbondanzieri, Elio A -- Zhuang, Xiaowei -- England -- Nature. 2009 Jan 22;457(7228):392-3. doi: 10.1038/457392a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19158782" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphatases/*chemistry/*metabolism ; Bacillus Phages/*enzymology ; DNA, Viral/chemistry/metabolism ; Hydrolysis ; Models, Biological ; Protein Structure, Quaternary ; Protein Subunits/chemistry/metabolism ; Virus Assembly
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  • 79
    Publication Date: 2009-02-20
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Muller-Landau, Helene C -- England -- Nature. 2009 Feb 19;457(7232):969-70. doi: 10.1038/457969a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19225510" target="_blank"〉PubMed〈/a〉
    Keywords: Africa ; Atmosphere/chemistry ; Biomass ; Carbon/analysis/*metabolism ; Carbon Dioxide/analysis/metabolism ; Models, Biological ; Trees/chemistry/growth & development/*metabolism ; *Tropical Climate ; Wilderness
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  • 80
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    Nature Publishing Group (NPG)
    Publication Date: 2009-02-20
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tonzani, Stefano -- England -- Nature. 2009 Feb 19;457(7232):974. doi: 10.1038/457974a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19225516" target="_blank"〉PubMed〈/a〉
    Keywords: Colloids/*chemistry ; *Magnetics ; Models, Biological ; Nanostructures/chemistry/ultrastructure ; Particle Size ; Water/chemistry
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  • 81
    Publication Date: 2009-04-28
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kutschera, U -- England -- Nature. 2009 Apr 23;458(7241):967. doi: 10.1038/458967c.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19396120" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; *Competitive Behavior ; Cooperative Behavior ; History, 19th Century ; Models, Biological ; *Selection, Genetic ; *Translating ; *Translations
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  • 82
    Publication Date: 2009-11-10
    Description: Direct reprogramming of somatic cells into induced pluripotent stem (iPS) cells can be achieved by overexpression of Oct4, Sox2, Klf4 and c-Myc transcription factors, but only a minority of donor somatic cells can be reprogrammed to pluripotency. Here we demonstrate that reprogramming by these transcription factors is a continuous stochastic process where almost all mouse donor cells eventually give rise to iPS cells on continued growth and transcription factor expression. Additional inhibition of the p53/p21 pathway or overexpression of Lin28 increased the cell division rate and resulted in an accelerated kinetics of iPS cell formation that was directly proportional to the increase in cell proliferation. In contrast, Nanog overexpression accelerated reprogramming in a predominantly cell-division-rate-independent manner. Quantitative analyses define distinct cell-division-rate-dependent and -independent modes for accelerating the stochastic course of reprogramming, and suggest that the number of cell divisions is a key parameter driving epigenetic reprogramming to pluripotency.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2789972/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2789972/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hanna, Jacob -- Saha, Krishanu -- Pando, Bernardo -- van Zon, Jeroen -- Lengner, Christopher J -- Creyghton, Menno P -- van Oudenaarden, Alexander -- Jaenisch, Rudolf -- R01 CA087869/CA/NCI NIH HHS/ -- R01 CA087869-09/CA/NCI NIH HHS/ -- R01 HD045022/HD/NICHD NIH HHS/ -- R01 HD045022-06/HD/NICHD NIH HHS/ -- R01-CA087869/CA/NCI NIH HHS/ -- R01-HDO45022/PHS HHS/ -- R37 CA084198/CA/NCI NIH HHS/ -- R37 CA084198-09/CA/NCI NIH HHS/ -- R37-CA084198/CA/NCI NIH HHS/ -- U54CA143874/CA/NCI NIH HHS/ -- England -- Nature. 2009 Dec 3;462(7273):595-601. doi: 10.1038/nature08592. Epub 2009 Nov 8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA. Hanna@wi.mit.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19898493" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Cell Differentiation ; Cell Division ; Cell Line ; *Cellular Reprogramming ; Gene Expression Regulation, Developmental ; Mice ; Mice, SCID ; Models, Biological ; Pluripotent Stem Cells/*cytology/*metabolism ; Time Factors ; Transcription Factors/genetics/metabolism
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  • 83
    Publication Date: 2009-04-03
    Description: Explaining the ecological causes of evolutionary diversification is a major focus of biology, but surprisingly little has been said about the effects of evolutionary diversification on ecosystems. The number of species in an ecosystem and their traits are key predictors of many ecosystem-level processes, such as rates of productivity, biomass sequestration and decomposition. Here we demonstrate short-term ecosystem-level effects of adaptive radiation in the threespine stickleback (Gasterosteus aculeatus) over the past 10,000 years. These fish have undergone recent parallel diversification in several lakes in coastal British Columbia, resulting in the formation of two specialized species (benthic and limnetic) from a generalist ancestor. Using a mesocosm experiment, we demonstrate that this diversification has strong effects on ecosystems, affecting prey community structure, total primary production, and the nature of dissolved organic materials that regulate the spectral properties of light transmission in the system. However, these ecosystem effects do not simply increase in their relative strength with increasing specialization and species richness; instead, they reflect the complex and indirect consequences of ecosystem engineering by sticklebacks. It is well known that ecological factors influence adaptive radiation. We demonstrate that adaptive radiation, even over short timescales, can have profound effects on ecosystems.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Harmon, Luke J -- Matthews, Blake -- Des Roches, Simone -- Chase, Jonathan M -- Shurin, Jonathan B -- Schluter, Dolph -- England -- Nature. 2009 Apr 30;458(7242):1167-70. doi: 10.1038/nature07974. Epub 2009 Apr 1.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Sciences, University of Idaho, Moscow, Idaho 83844-3051, USA. lukeh@uidaho.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19339968" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biodiversity ; *Biological Evolution ; Biomass ; British Columbia ; *Ecosystem ; Fishes/*classification/*physiology ; Food Chain ; Fresh Water ; Genetic Speciation ; Models, Biological ; Population Density ; Predatory Behavior
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  • 84
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    Nature Publishing Group (NPG)
    Publication Date: 2009-06-19
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Aguzzi, Adriano -- England -- Nature. 2009 Jun 18;459(7249):924-5. doi: 10.1038/459924a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19536253" target="_blank"〉PubMed〈/a〉
    Keywords: Amyloid/metabolism ; Animals ; Humans ; Models, Biological ; Peptides/metabolism ; Prion Diseases/*metabolism/pathology/transmission ; Prions/*chemistry/*metabolism ; Protein Denaturation ; tau Proteins/genetics/metabolism
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  • 85
    Publication Date: 2009-10-02
    Description: Down Syndrome cell adhesion molecule (Dscam) genes encode neuronal cell recognition proteins of the immunoglobulin superfamily. In Drosophila, Dscam1 generates 19,008 different ectodomains by alternative splicing of three exon clusters, each encoding half or a complete variable immunoglobulin domain. Identical isoforms bind to each other, but rarely to isoforms differing at any one of the variable immunoglobulin domains. Binding between isoforms on opposing membranes promotes repulsion. Isoform diversity provides the molecular basis for neurite self-avoidance. Self-avoidance refers to the tendency of branches from the same neuron (self-branches) to selectively avoid one another. To ensure that repulsion is restricted to self-branches, different neurons express different sets of isoforms in a biased stochastic fashion. Genetic studies demonstrated that Dscam1 diversity has a profound role in wiring the fly brain. Here we show how many isoforms are required to provide an identification system that prevents non-self branches from inappropriately recognizing each other. Using homologous recombination, we generated mutant animals encoding 12, 24, 576 and 1,152 potential isoforms. Mutant animals with deletions encoding 4,752 and 14,256 isoforms were also analysed. Branching phenotypes were assessed in three classes of neurons. Branching patterns improved as the potential number of isoforms increased, and this was independent of the identity of the isoforms. Although branching defects in animals with 1,152 potential isoforms remained substantial, animals with 4,752 isoforms were indistinguishable from wild-type controls. Mathematical modelling studies were consistent with the experimental results that thousands of isoforms are necessary to ensure acquisition of unique Dscam1 identities in many neurons. We conclude that thousands of isoforms are essential to provide neurons with a robust discrimination mechanism to distinguish between self and non-self during self-avoidance.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2836808/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2836808/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hattori, Daisuke -- Chen, Yi -- Matthews, Benjamin J -- Salwinski, Lukasz -- Sabatti, Chiara -- Grueber, Wesley B -- Zipursky, S Lawrence -- F31 NS060341/NS/NINDS NIH HHS/ -- R01 DC006485/DC/NIDCD NIH HHS/ -- R01 DC006485-07/DC/NIDCD NIH HHS/ -- R01 HD040279/HD/NICHD NIH HHS/ -- R01 HD040279-05/HD/NICHD NIH HHS/ -- T32 HD007430/HD/NICHD NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2009 Oct 1;461(7264):644-8. doi: 10.1038/nature08431.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19794492" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Alternative Splicing ; Animals ; Brain/cytology/metabolism ; Cell Adhesion Molecules/*chemistry/genetics/*metabolism ; Drosophila Proteins/*chemistry/genetics/*metabolism ; Drosophila melanogaster/*cytology/genetics/*metabolism ; Female ; Male ; Models, Biological ; Mushroom Bodies/cytology/metabolism ; Neurites/*metabolism ; Protein Isoforms/chemistry/genetics/metabolism ; Sequence Deletion ; Stochastic Processes
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  • 86
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    Nature Publishing Group (NPG)
    Publication Date: 2009-09-11
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Nicholls, Henry -- England -- Nature. 2009 Sep 10;461(7261):164-6. doi: 10.1038/461164a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19741680" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Biological Evolution ; Developmental Biology ; Fossils ; Hagfishes/*anatomy & histology/*classification/embryology/genetics ; Head/anatomy & histology ; Humans ; Lampreys/*anatomy & histology/*classification/embryology/genetics ; MicroRNAs/genetics/metabolism ; Models, Biological ; Phylogeny ; Sharks/anatomy & histology/classification/embryology
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  • 87
    Publication Date: 2009-02-20
    Description: The assembly of complex structures out of simple colloidal building blocks is of practical interest for building materials with unique optical properties (for example photonic crystals and DNA biosensors) and is of fundamental importance in improving our understanding of self-assembly processes occurring on molecular to macroscopic length scales. Here we demonstrate a self-assembly principle that is capable of organizing a diverse set of colloidal particles into highly reproducible, rotationally symmetric arrangements. The structures are assembled using the magnetostatic interaction between effectively diamagnetic and paramagnetic particles within a magnetized ferrofluid. The resulting multipolar geometries resemble electrostatic charge configurations such as axial quadrupoles ('Saturn rings'), axial octupoles ('flowers'), linear quadrupoles (poles) and mixed multipole arrangements ('two tone'), which represent just a few examples of the type of structure that can be built using this technique.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Erb, Randall M -- Son, Hui S -- Samanta, Bappaditya -- Rotello, Vincent M -- Yellen, Benjamin B -- England -- Nature. 2009 Feb 19;457(7232):999-1002. doi: 10.1038/nature07766.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Duke University, Department of Mechanical Engineering and Materials Science, Center for Biologically Inspired Materials and Material Systems, Box 90300, Hudson Hall, Durham, North Carolina 27708, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19225522" target="_blank"〉PubMed〈/a〉
    Keywords: Colloids/*chemistry ; *Magnetics ; Microscopy, Electron, Scanning ; Microspheres ; Models, Biological ; Nanostructures/chemistry/ultrastructure ; Particle Size ; Water/chemistry
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  • 88
    Publication Date: 2009-02-06
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Allen, Nicola J -- Barres, Ben A -- England -- Nature. 2009 Feb 5;457(7230):675-7. doi: 10.1038/457675a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19194443" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Astrocytes/physiology ; Biological Evolution ; Brain/*cytology/embryology/pathology/*physiology ; Cell Communication ; Cell Lineage ; Homeostasis ; Humans ; Models, Biological ; Nerve Net/physiology ; Nervous System Diseases/pathology/physiopathology ; Neural Pathways/physiology ; Neuroglia/classification/cytology/pathology/*physiology ; Neurons/cytology/physiology ; Oligodendroglia/pathology/physiology ; Schwann Cells/pathology/physiology
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  • 89
    Publication Date: 2009-09-04
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vasquez, Valeria -- Perozo, Eduardo -- England -- Nature. 2009 Sep 3;461(7260):47-9. doi: 10.1038/461047a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19727188" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Proteins/*chemistry/*metabolism ; Crystallography, X-Ray ; Ion Channel Gating/*physiology ; Ion Channels/*chemistry/*metabolism ; Models, Biological ; Models, Molecular ; Mycobacterium tuberculosis/chemistry ; Pressure ; Protein Structure, Quaternary ; Staphylococcus aureus/*chemistry
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  • 90
    Publication Date: 2009-07-25
    Description: Spatially synchronized fluctuations in system state are common in physical and biological systems ranging from individual atoms to species as diverse as viruses, insects and mammals. Although the causal factors are well known for many synchronized phenomena, several processes concurrently have an impact on spatial synchrony of species, making their separate effects and interactions difficult to quantify. Here we develop a general stochastic model of predator-prey spatial dynamics to predict the outcome of a laboratory microcosm experiment testing for interactions among all known synchronizing factors: (1) dispersal of individuals between populations; (2) spatially synchronous fluctuations in exogenous environmental factors (the Moran effect); and (3) interactions with other species (for example, predators) that are themselves spatially synchronized. The Moran effect synchronized populations of the ciliate protist Tetrahymena pyriformis; however, dispersal only synchronized prey populations in the presence of the predator Euplotes patella. Both model and data indicate that synchrony depends on cyclic dynamics generated by the predator. Dispersal, but not the Moran effect, 'phase-locks' cycles, which otherwise become 'decoherent' and drift out of phase. In the absence of cycles, phase-locking is not possible and the synchronizing effect of dispersal is negligible. Interspecific interactions determine population synchrony, not by providing an additional source of synchronized fluctuations, but by altering population dynamics and thereby enhancing the action of dispersal. Our results are robust to wide variation in model parameters representative of many natural predator-prey or host-pathogen systems. This explains why cyclic systems provide many of the most dramatic examples of spatial synchrony in nature.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vasseur, David A -- Fox, Jeremy W -- England -- Nature. 2009 Aug 20;460(7258):1007-10. doi: 10.1038/nature08208. Epub 2009 Jul 22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut 06520, USA. david.vasseur@yale.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19626006" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Euplotes/*physiology ; *Food Chain ; Models, Biological ; Population Dynamics ; Predatory Behavior/*physiology ; Stochastic Processes ; Tetrahymena pyriformis/*physiology
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  • 91
    Publication Date: 2009-06-12
    Description: Natural products containing phosphorus-carbon bonds have found widespread use in medicine and agriculture. One such compound, phosphinothricin tripeptide, contains the unusual amino acid phosphinothricin attached to two alanine residues. Synthetic phosphinothricin (glufosinate) is a component of two top-selling herbicides (Basta and Liberty), and is widely used with resistant transgenic crops including corn, cotton and canola. Recent genetic and biochemical studies showed that during phosphinothricin tripeptide biosynthesis 2-hydroxyethylphosphonate (HEP) is converted to hydroxymethylphosphonate (HMP). Here we report the in vitro reconstitution of this unprecedented C(sp(3))-C(sp(3)) bond cleavage reaction and X-ray crystal structures of the enzyme. The protein is a mononuclear non-haem iron(ii)-dependent dioxygenase that converts HEP to HMP and formate. In contrast to most other members of this family, the oxidative consumption of HEP does not require additional cofactors or the input of exogenous electrons. The current study expands the scope of reactions catalysed by the 2-His-1-carboxylate mononuclear non-haem iron family of enzymes.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2874955/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2874955/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cicchillo, Robert M -- Zhang, Houjin -- Blodgett, Joshua A V -- Whitteck, John T -- Li, Gongyong -- Nair, Satish K -- van der Donk, Wilfred A -- Metcalf, William W -- P01 GM077596/GM/NIGMS NIH HHS/ -- P01 GM077596-03/GM/NIGMS NIH HHS/ -- R01 GM059334/GM/NIGMS NIH HHS/ -- R01 GM059334-09/GM/NIGMS NIH HHS/ -- R01 GM59334/GM/NIGMS NIH HHS/ -- England -- Nature. 2009 Jun 11;459(7248):871-4. doi: 10.1038/nature07972.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19516340" target="_blank"〉PubMed〈/a〉
    Keywords: Aminobutyrates/*chemistry/*metabolism ; Biocatalysis ; Crystallography, X-Ray ; Dioxygenases/chemistry/genetics/*metabolism ; Escherichia coli ; Formates/metabolism ; Magnetic Resonance Spectroscopy ; Mass Spectrometry ; Models, Biological ; Models, Molecular ; Molecular Conformation ; Organophosphonates/metabolism
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  • 92
    Publication Date: 2009-08-14
    Description: Ecological communities characteristically contain a wide diversity of species with important functional, economic and aesthetic value. Ecologists have long questioned how this diversity is maintained. Classic theory shows that stable coexistence requires competitors to differ in their niches; this has motivated numerous investigations of ecological differences presumed to maintain diversity. That niche differences are key to coexistence, however, has recently been challenged by the neutral theory of biodiversity, which explains coexistence with the equivalence of competitors. The ensuing controversy has motivated calls for a better understanding of the collective importance of niche differences for the diversity observed in ecological communities. Here we integrate theory and experimentation to show that niche differences collectively stabilize the dynamics of experimental communities of serpentine annual plants. We used field-parameterized population models to develop a null expectation for community dynamics without the stabilizing effects of niche differences. The population growth rates predicted by this null model varied by several orders of magnitude between species, which is sufficient for rapid competitive exclusion. Moreover, after two generations of community change in the field, Shannon diversity was over 50 per cent greater in communities stabilized by niche differences relative to those exhibiting dynamics predicted by the null model. Finally, in an experiment manipulating species' relative abundances, population growth rates increased when species became rare--the demographic signature of niche differences. Our work thus provides strong evidence that species differences have a critical role in stabilizing species diversity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Levine, Jonathan M -- HilleRisLambers, Janneke -- England -- Nature. 2009 Sep 10;461(7261):254-7. doi: 10.1038/nature08251. Epub 2009 Aug 12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California 93106, USA. levine@lifesci.ucsb.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19675568" target="_blank"〉PubMed〈/a〉
    Keywords: *Biodiversity ; California ; *Ecosystem ; Models, Biological ; Plant Development ; *Plant Physiological Phenomena ; Plants/classification ; Population Dynamics ; Seeds/physiology
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  • 93
    Publication Date: 2009-02-20
    Description: The response of terrestrial vegetation to a globally changing environment is central to predictions of future levels of atmospheric carbon dioxide. The role of tropical forests is critical because they are carbon-dense and highly productive. Inventory plots across Amazonia show that old-growth forests have increased in carbon storage over recent decades, but the response of one-third of the world's tropical forests in Africa is largely unknown owing to an absence of spatially extensive observation networks. Here we report data from a ten-country network of long-term monitoring plots in African tropical forests. We find that across 79 plots (163 ha) above-ground carbon storage in live trees increased by 0.63 Mg C ha(-1) yr(-1) between 1968 and 2007 (95% confidence interval (CI), 0.22-0.94; mean interval, 1987-96). Extrapolation to unmeasured forest components (live roots, small trees, necromass) and scaling to the continent implies a total increase in carbon storage in African tropical forest trees of 0.34 Pg C yr(-1) (CI, 0.15-0.43). These reported changes in carbon storage are similar to those reported for Amazonian forests per unit area, providing evidence that increasing carbon storage in old-growth forests is a pan-tropical phenomenon. Indeed, combining all standardized inventory data from this study and from tropical America and Asia together yields a comparable figure of 0.49 Mg C ha(-1) yr(-1) (n = 156; 562 ha; CI, 0.29-0.66; mean interval, 1987-97). This indicates a carbon sink of 1.3 Pg C yr(-1) (CI, 0.8-1.6) across all tropical forests during recent decades. Taxon-specific analyses of African inventory and other data suggest that widespread changes in resource availability, such as increasing atmospheric carbon dioxide concentrations, may be the cause of the increase in carbon stocks, as some theory and models predict.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lewis, Simon L -- Lopez-Gonzalez, Gabriela -- Sonke, Bonaventure -- Affum-Baffoe, Kofi -- Baker, Timothy R -- Ojo, Lucas O -- Phillips, Oliver L -- Reitsma, Jan M -- White, Lee -- Comiskey, James A -- Djuikouo K, Marie-Noel -- Ewango, Corneille E N -- Feldpausch, Ted R -- Hamilton, Alan C -- Gloor, Manuel -- Hart, Terese -- Hladik, Annette -- Lloyd, Jon -- Lovett, Jon C -- Makana, Jean-Remy -- Malhi, Yadvinder -- Mbago, Frank M -- Ndangalasi, Henry J -- Peacock, Julie -- Peh, Kelvin S-H -- Sheil, Douglas -- Sunderland, Terry -- Swaine, Michael D -- Taplin, James -- Taylor, David -- Thomas, Sean C -- Votere, Raymond -- Woll, Hannsjorg -- England -- Nature. 2009 Feb 19;457(7232):1003-6. doi: 10.1038/nature07771.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Earth and Biosphere Institute, School of Geography, University of Leeds, Leeds LS2 9JT, UK. s.l.lewis@leeds.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19225523" target="_blank"〉PubMed〈/a〉
    Keywords: Africa ; Atmosphere/chemistry ; Biomass ; Carbon/analysis/*metabolism ; Carbon Dioxide/analysis/metabolism ; Models, Biological ; Trees/anatomy & histology/chemistry/growth & development/*metabolism ; *Tropical Climate ; Wilderness ; Wood/analysis/chemistry
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  • 94
    Publication Date: 2009-06-19
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Clark, Andrew J -- Summers, Adam P -- England -- Nature. 2009 Jun 18;459(7249):919-20. doi: 10.1038/459919a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19536249" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biomechanical Phenomena ; Body Weight ; Friction ; Gait/physiology ; Locomotion/*physiology ; Models, Biological ; Snakes/*physiology
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  • 95
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    Unknown
    Nature Publishing Group (NPG)
    Publication Date: 2009-06-12
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Seastedt, Tim -- England -- Nature. 2009 Jun 11;459(7248):783-4. doi: 10.1038/459783a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19516327" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Ecosystem ; Europe ; Models, Biological ; *Plant Development ; Plants/*microbiology ; Population Growth ; United States
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  • 96
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    Unknown
    Nature Publishing Group (NPG)
    Publication Date: 2009-05-02
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Seehausen, Ole -- England -- Nature. 2009 Apr 30;458(7242):1122-3. doi: 10.1038/4581122a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19407790" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biodiversity ; *Biological Evolution ; British Columbia ; *Ecosystem ; Fishes/*classification/*physiology ; Food Chain ; Fresh Water ; Genetic Speciation ; Models, Biological
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  • 97
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    Unknown
    Nature Publishing Group (NPG)
    Publication Date: 2009-01-17
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sendtner, Michael -- England -- Nature. 2009 Jan 15;457(7227):269-70. doi: 10.1038/457269a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19148087" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Cell Differentiation/drug effects ; Cell Separation ; *Cellular Reprogramming/drug effects ; Child ; Female ; Fibroblasts/cytology ; Humans ; Mice ; Models, Biological ; Motor Neurons/drug effects/metabolism/*pathology ; Muscular Atrophy, Spinal/drug therapy/metabolism/*pathology ; Pluripotent Stem Cells/cytology/drug effects/metabolism/*pathology ; Skin/*cytology ; Survival of Motor Neuron 1 Protein/genetics/metabolism
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  • 98
    Publication Date: 2009-07-03
    Description: Environmental conditions during the past 24 million years are thought to have been favourable for enhanced rates of atmospheric carbon dioxide drawdown by silicate chemical weathering. Proxy records indicate, however, that the Earth's atmospheric carbon dioxide concentrations did not fall below about 200-250 parts per million during this period. The stabilization of atmospheric carbon dioxide concentrations near this minimum value suggests that strong negative feedback mechanisms inhibited further drawdown of atmospheric carbon dioxide by high rates of global silicate rock weathering. Here we investigate one possible negative feedback mechanism, occurring under relatively low carbon dioxide concentrations and in warm climates, that is related to terrestrial plant productivity and its role in the decomposition of silicate minerals. We use simulations of terrestrial and geochemical carbon cycles and available experimental evidence to show that vegetation activity in upland regions of active orogens was severely limited by near-starvation of carbon dioxide in combination with global warmth over this period. These conditions diminished biotic-driven silicate rock weathering and thereby attenuated an important long-term carbon dioxide sink. Although our modelling results are semi-quantitative and do not capture the full range of biogeochemical feedbacks that could influence the climate, our analysis indicates that the dynamic equilibrium between plants, climate and the geosphere probably buffered the minimum atmospheric carbon dioxide concentrations over the past 24 million years.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pagani, Mark -- Caldeira, Ken -- Berner, Robert -- Beerling, David J -- England -- Nature. 2009 Jul 2;460(7251):85-8. doi: 10.1038/nature08133.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Geology and Geophysics, Yale University, New Haven, Connecticut 06520, USA. mark.pagani@yale.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19571882" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Atmosphere/*chemistry ; Biomass ; Carbon Dioxide/*analysis ; Climate ; Eukaryota ; Geologic Sediments/*chemistry ; Geology ; History, Ancient ; Ice Cover ; Models, Biological ; Plant Leaves/metabolism ; Plant Roots/growth & development ; Plant Transpiration ; Plants/*metabolism ; Silicates/*chemistry
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  • 99
    Publication Date: 2009-03-06
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Friend, Stephen -- Schadt, Eric -- England -- Nature. 2009 Mar 5;458(7234):13. doi: 10.1038/458013a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19262635" target="_blank"〉PubMed〈/a〉
    Keywords: *Access to Information ; Animals ; *Biomedical Research ; Humans ; *Internet ; Mice ; Models, Biological ; Time Factors
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  • 100
    Publication Date: 2009-11-20
    Description: Genomic DNA is replicated by two DNA polymerase molecules, one of which works in close association with the helicase to copy the leading-strand template in a continuous manner while the second copies the already unwound lagging-strand template in a discontinuous manner through the synthesis of Okazaki fragments. Considering that the lagging-strand polymerase has to recycle after the completion of every Okazaki fragment through the slow steps of primer synthesis and hand-off to the polymerase, it is not understood how the two strands are synthesized with the same net rate. Here we show, using the T7 replication proteins, that RNA primers are made 'on the fly' during ongoing DNA synthesis and that the leading-strand T7 replisome does not pause during primer synthesis, contrary to previous reports. Instead, the leading-strand polymerase remains limited by the speed of the helicase; it therefore synthesizes DNA more slowly than the lagging-strand polymerase. We show that the primase-helicase T7 gp4 maintains contact with the priming sequence during ongoing DNA synthesis; the nascent lagging-strand template therefore organizes into a priming loop that keeps the primer in physical proximity to the replication complex. Our findings provide three synergistic mechanisms of coordination: first, primers are made concomitantly with DNA synthesis; second, the priming loop ensures efficient primer use and hand-off to the polymerase; and third, the lagging-strand polymerase copies DNA faster, which allows it to keep up with leading-strand DNA synthesis overall.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2896039/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2896039/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pandey, Manjula -- Syed, Salman -- Donmez, Ilker -- Patel, Gayatri -- Ha, Taekjip -- Patel, Smita S -- GM065367/GM/NIGMS NIH HHS/ -- GM55310/GM/NIGMS NIH HHS/ -- R01 GM055310/GM/NIGMS NIH HHS/ -- R01 GM055310-14/GM/NIGMS NIH HHS/ -- R01 GM065367/GM/NIGMS NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2009 Dec 17;462(7275):940-3. doi: 10.1038/nature08611. Epub 2009 Nov 18.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19924126" target="_blank"〉PubMed〈/a〉
    Keywords: Bacteriophage T7/*enzymology/genetics/*physiology ; DNA Primase/chemistry/metabolism ; DNA Replication/*physiology ; DNA, Viral/biosynthesis/metabolism ; DNA-Directed DNA Polymerase/chemistry/metabolism ; Fluorescence Resonance Energy Transfer ; Kinetics ; Models, Biological ; Multienzyme Complexes/chemistry/metabolism ; Protein Structure, Tertiary ; RNA/biosynthesis ; Time Factors
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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