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  • 1
    Publikationsdatum: 2009-12-18
    Beschreibung: Avian brood parasites and their hosts provide model systems for investigating links between recognition, learning, and their fitness consequences. One major evolutionary puzzle has continued to capture the attention of naturalists for centuries: why do hosts of brood parasites generally fail to recognize parasitic offspring after they have hatched from the egg, even when the host and parasitic chicks differ to almost comic degrees? One prominent theory to explain this pattern proposes that the costs of mistakenly learning to recognize the wrong offspring make recognition maladaptive. Here we show that American coots, Fulica americana, can recognize and reject parasitic chicks in their brood by using learned cues, despite the fact that the hosts and the brood parasites are of the same species. A series of chick cross-fostering experiments confirm that coots use first-hatched chicks in a brood as referents to learn to recognize their own chicks and then discriminate against later-hatched parasitic chicks in the same brood. When experimentally provided with the wrong reference chicks, coots can be induced to discriminate against their own offspring, confirming that the learning errors proposed by theory can exist. However, learning based on hatching order is reliable in naturally parasitized coot nests because host eggs hatch predictably ahead of parasite eggs. Conversely, a lack of reliable information may help to explain why the evolution of chick recognition is not more common in hosts of most interspecific brood parasites.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shizuka, Daizaburo -- Lyon, Bruce E -- England -- Nature. 2010 Jan 14;463(7278):223-6. doi: 10.1038/nature08655. Epub 2009 Dec 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California 95064, USA. shizuka@biology.ucsc.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20016486" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Biological Evolution ; Birds/*parasitology/*physiology ; British Columbia ; Cues ; Discrimination Learning/*physiology ; Feeding Behavior/physiology ; Genetic Fitness ; Nesting Behavior/*physiology ; Ovum/growth & development ; Pattern Recognition, Visual/physiology ; Survival Rate ; Time Factors ; Wetlands
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2009-12-23
    Beschreibung: 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〉
    Schlagwort(e): 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
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2009-12-18
    Beschreibung: All cancers carry somatic mutations. A subset of these somatic alterations, termed driver mutations, confer selective growth advantage and are implicated in cancer development, whereas the remainder are passengers. Here we have sequenced the genomes of a malignant melanoma and a lymphoblastoid cell line from the same person, providing the first comprehensive catalogue of somatic mutations from an individual cancer. The catalogue provides remarkable insights into the forces that have shaped this cancer genome. The dominant mutational signature reflects DNA damage due to ultraviolet light exposure, a known risk factor for malignant melanoma, whereas the uneven distribution of mutations across the genome, with a lower prevalence in gene footprints, indicates that DNA repair has been preferentially deployed towards transcribed regions. The results illustrate the power of a cancer genome sequence to reveal traces of the DNA damage, repair, mutation and selection processes that were operative years before the cancer became symptomatic.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3145108/" 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/PMC3145108/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pleasance, Erin D -- Cheetham, R Keira -- Stephens, Philip J -- McBride, David J -- Humphray, Sean J -- Greenman, Chris D -- Varela, Ignacio -- Lin, Meng-Lay -- Ordonez, Gonzalo R -- Bignell, Graham R -- Ye, Kai -- Alipaz, Julie -- Bauer, Markus J -- Beare, David -- Butler, Adam -- Carter, Richard J -- Chen, Lina -- Cox, Anthony J -- Edkins, Sarah -- Kokko-Gonzales, Paula I -- Gormley, Niall A -- Grocock, Russell J -- Haudenschild, Christian D -- Hims, Matthew M -- James, Terena -- Jia, Mingming -- Kingsbury, Zoya -- Leroy, Catherine -- Marshall, John -- Menzies, Andrew -- Mudie, Laura J -- Ning, Zemin -- Royce, Tom -- Schulz-Trieglaff, Ole B -- Spiridou, Anastassia -- Stebbings, Lucy A -- Szajkowski, Lukasz -- Teague, Jon -- Williamson, David -- Chin, Lynda -- Ross, Mark T -- Campbell, Peter J -- Bentley, David R -- Futreal, P Andrew -- Stratton, Michael R -- 077012/Z/05/Z/Wellcome Trust/United Kingdom -- 088340/Wellcome Trust/United Kingdom -- 093867/Wellcome Trust/United Kingdom -- England -- Nature. 2010 Jan 14;463(7278):191-6. doi: 10.1038/nature08658. Epub 2009 Dec 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20016485" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Adult ; Cell Line, Tumor ; DNA Damage/genetics ; DNA Mutational Analysis ; DNA Repair/genetics ; Gene Dosage/genetics ; Genes, Neoplasm/*genetics ; Genome, Human/*genetics ; Humans ; Loss of Heterozygosity/genetics ; Male ; Melanoma/etiology/genetics ; MicroRNAs/genetics ; Mutagenesis, Insertional/genetics ; Mutation/*genetics ; Neoplasms/etiology/*genetics ; Polymorphism, Single Nucleotide/genetics ; Precision Medicine ; Sequence Deletion/genetics ; Ultraviolet Rays
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2009-12-17
    Beschreibung: Recent research on changing fears has examined targeting reconsolidation. During reconsolidation, stored information is rendered labile after being retrieved. Pharmacological manipulations at this stage result in an inability to retrieve the memories at later times, suggesting that they are erased or persistently inhibited. Unfortunately, the use of these pharmacological manipulations in humans can be problematic. Here we introduce a non-invasive technique to target the reconsolidation of fear memories in humans. We provide evidence that old fear memories can be updated with non-fearful information provided during the reconsolidation window. As a consequence, fear responses are no longer expressed, an effect that lasted at least a year and was selective only to reactivated memories without affecting others. These findings demonstrate the adaptive role of reconsolidation as a window of opportunity to rewrite emotional memories, and suggest a non-invasive technique that can be used safely in humans to prevent the return of fear.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3640262/" 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/PMC3640262/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Schiller, Daniela -- Monfils, Marie-H -- Raio, Candace M -- Johnson, David C -- Ledoux, Joseph E -- Phelps, Elizabeth A -- K05 MH067048/MH/NIMH NIH HHS/ -- P50 MH058911/MH/NIMH NIH HHS/ -- R01 MH038774/MH/NIMH NIH HHS/ -- R01 MH046516/MH/NIMH NIH HHS/ -- R21 MH072279/MH/NIMH NIH HHS/ -- R37 MH038774/MH/NIMH NIH HHS/ -- Canadian Institutes of Health Research/Canada -- England -- Nature. 2010 Jan 7;463(7277):49-53. doi: 10.1038/nature08637. Epub 2009 Dec 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Neural Science, New York University, New York, New York 10003, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20010606" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Conditioning, Classical/*physiology ; Cues ; Electrodes ; Electroshock ; Extinction, Psychological/*physiology ; Fear/*physiology/*psychology ; Humans ; Memory/*physiology ; Models, Neurological ; Models, Psychological ; Neuronal Plasticity/*physiology ; Photic Stimulation ; Time Factors
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
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    Unbekannt
    Nature Publishing Group (NPG)
    Publikationsdatum: 2008-05-08
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wadman, Meredith -- England -- Nature. 2008 May 1;453(7191):9. doi: 10.1038/453009a.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18461710" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): *Federal Government ; Genetic Privacy/*legislation & jurisprudence ; Genetics, Medical/*legislation & jurisprudence ; Genomics/legislation & jurisprudence/trends ; Humans ; Individuality ; *Prejudice ; United States
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Publikationsdatum: 2008-03-28
    Beschreibung: Although information storage in the central nervous system is thought to be primarily mediated by various forms of synaptic plasticity, other mechanisms, such as modifications in membrane excitability, are available. Local dendritic spikes are nonlinear voltage events that are initiated within dendritic branches by spatially clustered and temporally synchronous synaptic input. That local spikes selectively respond only to appropriately correlated input allows them to function as input feature detectors and potentially as powerful information storage mechanisms. However, it is currently unknown whether any effective form of local dendritic spike plasticity exists. Here we show that the coupling between local dendritic spikes and the soma of rat hippocampal CA1 pyramidal neurons can be modified in a branch-specific manner through an N-methyl-d-aspartate receptor (NMDAR)-dependent regulation of dendritic Kv4.2 potassium channels. These data suggest that compartmentalized changes in branch excitability could store multiple complex features of synaptic input, such as their spatio-temporal correlation. We propose that this 'branch strength potentiation' represents a previously unknown form of information storage that is distinct from that produced by changes in synaptic efficacy both at the mechanistic level and in the type of information stored.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Losonczy, Attila -- Makara, Judit K -- Magee, Jeffrey C -- England -- Nature. 2008 Mar 27;452(7186):436-41. doi: 10.1038/nature06725.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Janelia Farm Research Campus, 19700 Helix Dr Ashburn, Virginia 20147, USA. losonczya@janelia.hhmi.org〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18368112" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Action Potentials/physiology ; Animals ; Cell Shape ; Dendrites/*physiology ; Ion Channel Gating ; Male ; Mice ; Models, Neurological ; Neuronal Plasticity/*physiology ; Pyramidal Cells/*cytology/*metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate/metabolism ; Shal Potassium Channels/deficiency/genetics/metabolism
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Publikationsdatum: 2008-11-14
    Beschreibung: Many complex behaviours, like speech or music, have a hierarchical organization with structure on many timescales, but it is not known how the brain controls the timing of behavioural sequences, or whether different circuits control different timescales of the behaviour. Here we address these issues by using temperature to manipulate the biophysical dynamics in different regions of the songbird forebrain involved in song production. We find that cooling the premotor nucleus HVC (formerly known as the high vocal centre) slows song speed across all timescales by up to 45 per cent but only slightly alters the acoustic structure, whereas cooling the downstream motor nucleus RA (robust nucleus of the arcopallium) has no observable effect on song timing. Our observations suggest that dynamics within HVC are involved in the control of song timing, perhaps through a chain-like organization. Local manipulation of brain temperature should be broadly applicable to the identification of neural circuitry that controls the timing of behavioural sequences and, more generally, to the study of the origin and role of oscillatory and other forms of brain dynamics in neural systems.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2723166/" 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/PMC2723166/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Long, Michael A -- Fee, Michale S -- DC009280/DC/NIDCD NIH HHS/ -- K99 DC009280/DC/NIDCD NIH HHS/ -- K99 DC009280-02/DC/NIDCD NIH HHS/ -- MH067105/MH/NIMH NIH HHS/ -- R01 MH067105/MH/NIMH NIH HHS/ -- R01 MH067105-04/MH/NIMH NIH HHS/ -- England -- Nature. 2008 Nov 13;456(7219):189-94. doi: 10.1038/nature07448.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, 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/19005546" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Cold Temperature ; Efferent Pathways/physiology ; Finches/*physiology ; High Vocal Center/*physiology ; Neurons/physiology ; Prosencephalon/*physiology/radiography ; Time Factors ; Vocalization, Animal/*physiology
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
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    Unbekannt
    Nature Publishing Group (NPG)
    Publikationsdatum: 2008-04-24
    Beschreibung: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wadman, Meredith -- England -- Nature. 2008 Apr 17;452(7189):788. doi: 10.1038/452788b.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18431822" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Genetic Counseling/trends ; *Genome, Human ; Genomics/economics/*trends ; History, 21st Century ; Humans ; Individuality ; Male ; Reference Standards ; Sequence Analysis, DNA/economics/*trends ; Time Factors
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 2008-03-14
    Beschreibung: Many tumour cells have elevated rates of glucose uptake but reduced rates of oxidative phosphorylation. This persistence of high lactate production by tumours in the presence of oxygen, known as aerobic glycolysis, was first noted by Otto Warburg more than 75 yr ago. How tumour cells establish this altered metabolic phenotype and whether it is essential for tumorigenesis is as yet unknown. Here we show that a single switch in a splice isoform of the glycolytic enzyme pyruvate kinase is necessary for the shift in cellular metabolism to aerobic glycolysis and that this promotes tumorigenesis. Tumour cells have been shown to express exclusively the embryonic M2 isoform of pyruvate kinase. Here we use short hairpin RNA to knockdown pyruvate kinase M2 expression in human cancer cell lines and replace it with pyruvate kinase M1. Switching pyruvate kinase expression to the M1 (adult) isoform leads to reversal of the Warburg effect, as judged by reduced lactate production and increased oxygen consumption, and this correlates with a reduced ability to form tumours in nude mouse xenografts. These results demonstrate that M2 expression is necessary for aerobic glycolysis and that this metabolic phenotype provides a selective growth advantage for tumour cells in vivo.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Christofk, Heather R -- Vander Heiden, Matthew G -- Harris, Marian H -- Ramanathan, Arvind -- Gerszten, Robert E -- Wei, Ru -- Fleming, Mark D -- Schreiber, Stuart L -- Cantley, Lewis C -- R01 GM056203/GM/NIGMS NIH HHS/ -- T32 CA009172/CA/NCI NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2008 Mar 13;452(7184):230-3. doi: 10.1038/nature06734.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18337823" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Alternative Splicing/*genetics ; Animals ; Cell Line, Tumor ; Cell Proliferation ; Fructosediphosphates/metabolism ; Gene Expression Regulation, Neoplastic ; Glycolysis ; Humans ; Lactic Acid/metabolism ; Lung Neoplasms/genetics/metabolism/pathology ; Male ; Mice ; Mice, Nude ; Neoplasm Transplantation ; Neoplasms/enzymology/genetics/*metabolism/*pathology ; Oxidative Phosphorylation ; Oxygen Consumption ; Pyruvate Kinase/*genetics/*metabolism ; Pyruvic Acid/metabolism
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 2008-05-16
    Beschreibung: Atmospheric methane is an important greenhouse gas and a sensitive indicator of climate change and millennial-scale temperature variability. Its concentrations over the past 650,000 years have varied between approximately 350 and approximately 800 parts per 10(9) by volume (p.p.b.v.) during glacial and interglacial periods, respectively. In comparison, present-day methane levels of approximately 1,770 p.p.b.v. have been reported. Insights into the external forcing factors and internal feedbacks controlling atmospheric methane are essential for predicting the methane budget in a warmer world. Here we present a detailed atmospheric methane record from the EPICA Dome C ice core that extends the history of this greenhouse gas to 800,000 yr before present. The average time resolution of the new data is approximately 380 yr and permits the identification of orbital and millennial-scale features. Spectral analyses indicate that the long-term variability in atmospheric methane levels is dominated by approximately 100,000 yr glacial-interglacial cycles up to approximately 400,000 yr ago with an increasing contribution of the precessional component during the four more recent climatic cycles. We suggest that changes in the strength of tropical methane sources and sinks (wetlands, atmospheric oxidation), possibly influenced by changes in monsoon systems and the position of the intertropical convergence zone, controlled the atmospheric methane budget, with an additional source input during major terminations as the retreat of the northern ice sheet allowed higher methane emissions from extending periglacial wetlands. Millennial-scale changes in methane levels identified in our record as being associated with Antarctic isotope maxima events are indicative of ubiquitous millennial-scale temperature variability during the past eight glacial cycles.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Loulergue, Laetitia -- Schilt, Adrian -- Spahni, Renato -- Masson-Delmotte, Valerie -- Blunier, Thomas -- Lemieux, Benedicte -- Barnola, Jean-Marc -- Raynaud, Dominique -- Stocker, Thomas F -- Chappellaz, Jerome -- England -- Nature. 2008 May 15;453(7193):383-6. doi: 10.1038/nature06950.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratoire de Glaciologie et Geophysique de l'Environnement, CNRS-Universite Joseph Fourier Grenoble, 54 Rue Moliere, 38402 St Martin d'Heres, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18480822" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Atmosphere/*chemistry ; Greenhouse Effect ; History, Ancient ; Ice Cover ; Methane/*analysis ; Temperature ; Time Factors ; Tropical Climate ; Wetlands
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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