219 resultados para 499
Resumo:
Conspecific aggregation of waterfowl in winter is a common example of animal flocking behaviour, yet patterns of relatedness and temporal substructure in such social groups remain poorly understood even in common species. A previous study based on mark-recapture data showed that Tufted Ducks Aythya fuligula caught on the same day were re-caught together in subsequent winters more often than expected by chance, suggesting stable assortments of ‘socially familiar’ individuals between wintering periods. The genetic relationships within these social groups were not clear. Based on 191 individuals genotyped at 10 microsatellite markers, we investigated the temporal genetic structure and patterns of relatedness among wintering Tufted Ducks at Lake Sempach, Switzerland, in two consecutive winters. We found no evidence of genetic differentiation between temporal groups within or between winters. The average levels of relatedness in temporal groups were low and not higher than expected in random assortments of individuals. However, Mantel tests performed for each sex separately revealed significant negative correlations between the pairwise relatedness coefficients and the number of days between the capture dates of pairs of wintering Tufted Duck in males and females. This pattern suggests the presence of a small number of co-migrating same-sex sibling pairs in wintering flocks of Tufted Ducks. Our findings provide one of the first genetic analyses of a common duck species outside the breeding season and contribute to the understanding of social interactions in long-distance migratory birds.
Resumo:
Sirtuins (SIRT1-7) are a highly conserved family of NAD(+)-dependent enzymes that control the activity of histone and nonhistone regulatory proteins. SIRT1 is purposed to promote longevity and to suppress the initiation of some cancers. Nevertheless, SIRT1 is reported to function as a tumor suppressor as well as an oncogenic protein. Our data show that compared with normal liver or surrounding tumor tissue, SIRT1 is strongly overexpressed in human hepatocellular carcinoma (HCC). In addition, human HCC cell lines (Hep3B, HepG2, HuH7, HLE, HLF, HepKK1, skHep1) were screened for the expression of the sirtuin family members and only SIRT1 was consistently overexpressed compared with normal hepatocytes. To determine its effect on HCC growth, SIRT1 activity was inhibited either with lentiviruses expressing short hairpin RNAs or with the small molecule inhibitor, cambinol. Knockdown or inhibition of SIRT1 activity had a cytostatic effect, characterized by an altered morphology, impaired proliferation, an increased expression of differentiation markers, and cellular senescence. In an orthotopic xenograft model, knockdown of SIRT1 resulted in 50% fewer animals developing tumors and cambinol treatment resulted in an overall lower tumor burden. Taken together, our data show that inhibition of SIRT1 in HCC cells impairs their proliferation in vitro and tumor formation in vivo. These data suggest that SIRT1 expression positively influences the growth of HCC and support further studies aimed to block its activity alone or in combination as a novel treatment strategy.
Resumo:
Connus sous le nom populaire de palafittes, les habitats préhistoriques construits sur les rives des lacs subalpins du Néolithique à l’aube de l’âge du Fer (entre 5300 et 700 av. J.-C.) offrent des informations exceptionnelles sur l’évolution culturelle d’une importante région européenne, grâce à la préservation remarquable des matériaux organiques, en particulier du bois. À partir de la deuxième moitié du XXe siècle, le perfectionnement des techniques de fouille subaquatiques et de la dendrochronologie permettront la construction d’un schéma chronologique précis pour l’Europe nord-alpine. Les recherches contribueront à des observations d’ordre écologique à l’échelle locale et régionale et à l’identification des rythmes de développement des villages. Sous l’égide de l'UNESCO, les années 2010 verront la constitution d’un inventaire vaste et uniforme des sites préhistoriques des lacs circumalpins, classés Patrimoine culturel mondial en juin 2011. De nombreux objets préhistoriques, romains et médiévaux ont été découverts entre 2003 et 2010, au Schnidejoch, un col des Alpes bernoises occidentales à 2756 m d’altitude, à la frontière entre les cantons de Berne et du Valais. Les hautes températures de l'été 2003 ont provoqué la fonte d'un petit champ de glace et mis en lumière les vestiges. Les recherches ont été programmées à la suite d’une série d’informations fournies par des randonneurs. Les objets en matière organique (bois, écorce de bouleau, cuir, fibres végétales) revêtent une très grande importance car ils ont permis l’obtention de plus d’une cinquantaine de datations radiocarbone ; elles indiquent le passage du col entre la moitié du Ve millénaire av. J.-C. et l’année 1000 de notre ère. En outre, les séries de datations suggèrent l’alternance de périodes de praticabilité et d’inaccessibilité du col. Le Schnidejoch est actuellement le plus ancien témoignage de la traversée des Alpes, reliant l‘Oberland bernois par les vallées de la Simme et du Rhône.
Les villages préhistoriques des bords des lacs circum-alpins entre le Ve et IVe millénaire av. J.-C.
Resumo:
Connus sous le nom populaire de palafittes, les habitats préhistoriques construits sur les rives des lacs subalpins du Néolithique à l’aube de l’âge du Fer (entre 5300 et 700 av. J.-C.) offrent des informations exceptionnelles sur l’évolution culturelle d’une importante région européenne, grâce à la préservation remarquable des matériaux organiques, en particulier du bois. À partir de la deuxième moitié du XXe siècle, le perfectionnement des techniques de fouille subaquatiques et de la dendrochronologie permettront la construction d’un schéma chronologique précis pour l’Europe nord-alpine. Les recherches contribueront à des observations d’ordre écologique à l’échelle locale et régionale et à l’identification des rythmes de développement des villages. Sous l’égide de l'UNESCO, les années 2010 verront la constitution d’un inventaire vaste et uniforme des sites préhistoriques des lacs circumalpins, classés Patrimoine culturel mondial en juin 2011.
Resumo:
In sheep, small ruminant lentiviruses cause an incurable, progressive, lymphoproliferative disease that affects millions of animals worldwide. Known as ovine progressive pneumonia virus (OPPV) in the U.S., and Visna/Maedi virus (VMV) elsewhere, these viruses reduce an animal's health, productivity, and lifespan. Genetic variation in the ovine transmembrane protein 154 gene (TMEM154) has been previously associated with OPPV infection in U.S. sheep. Sheep with the ancestral TMEM154 haplotype encoding glutamate (E) at position 35, and either form of an N70I variant, were highly-susceptible compared to sheep homozygous for the K35 missense mutation. Our current overall aim was to characterize TMEM154 in sheep from around the world to develop an efficient genetic test for reduced susceptibility. The average frequency of TMEM154 E35 among 74 breeds was 0.51 and indicated that highly-susceptible alleles were present in most breeds around the world. Analysis of whole genome sequences from an international panel of 75 sheep revealed more than 1,300 previously unreported polymorphisms in a 62 kb region containing TMEM154 and confirmed that the most susceptible haplotypes were distributed worldwide. Novel missense mutations were discovered in the signal peptide (A13V) and the extracellular domains (E31Q, I74F, and I102T) of TMEM154. A matrix-assisted laser desorption/ionization-time-of flight mass spectrometry (MALDI-TOF MS) assay was developed to detect these and six previously reported missense and two deletion mutations in TMEM154. In blinded trials, the call rate for the eight most common coding polymorphisms was 99.4% for 499 sheep tested and 96.0% of the animals were assigned paired TMEM154 haplotypes (i.e., diplotypes). The widespread distribution of highly-susceptible TMEM154 alleles suggests that genetic testing and selection may improve the health and productivity of infected flocks.
Resumo:
In der Antike haben jüdische Autoren in ganz unterschiedlichen literarischen Gefäßen die Tora mit häufig bemerkenswerter inhaltlicher Freiheit für sich gedeutet und weiter gesponnen. Wie auf einer Drehbühne konnten biblische Texte immer wieder neu inszeniert werden - ohne, dass der Urtext deswegen in Frage gestellt werden musste. Die Tora war die Vorlage für unterschiedlichste Deutungen der eigenen Lebenswelten. René Bloch untersucht solche literarischen Imaginationen und deren Entstehungskontexte. Die in diesem Band versammelten Texte sind aus den Tria Corda-Vorlesungen an der Universität Jena hervorgegangen. Vier Texte aus der jüdischen Diaspora und Palästina stehen im Zentrum: der jüdisch-hellenistische Liebesroman Joseph und Aseneth, die Moses-Biographie des Philon von Alexandrien, das Buch der Biblischen Altertümer des Pseudo-Philo und schließlich - über die Antike hinaus, aber eng mit der Antike verbunden - der Josippon, eine hebräische Neufassung der biblischen Geschichte und des jüdisch-römischen Kriegs aus dem Italien des 10. Jahrhunderts. Die literarischen Genres der diskutierten Texte reichen vom Roman über das religionsphilosophische Traktat bis zur Geschichtsschreibung. Alle vier Autoren nehmen biblische Figuren auf und schreiben deren Geschichten um und weiter. Alle vier Texte sind stark geprägt von ihrem zeitlichen und geographischen Entstehungskontext und spiegeln ein komplexes Verhältnis zur nichtjüdischen Umwelt wider: Zum einen stehen sie für ein authentisches, teils gar wegweisendes Judentum ein. Zum andern sind sie aber auch um Verbindungen mit der Mehrheitsgesellschaft bemüht.
Resumo:
Climate targets are designed to inform policies that would limit the magnitude and impacts of climate change caused by anthropogenic emissions of greenhouse gases and other substances. The target that is currently recognized by most world governments1 places a limit of two degrees Celsius on the global mean warming since preindustrial times. This would require large sustained reductions in carbon dioxide emissions during the twenty-first century and beyond2, 3, 4. Such a global temperature target, however, is not sufficient to control many other quantities, such as transient sea level rise5, ocean acidification6, 7 and net primary production on land8, 9. Here, using an Earth system model of intermediate complexity (EMIC) in an observation-informed Bayesian approach, we show that allowable carbon emissions are substantially reduced when multiple climate targets are set. We take into account uncertainties in physical and carbon cycle model parameters, radiative efficiencies10, climate sensitivity11 and carbon cycle feedbacks12, 13 along with a large set of observational constraints. Within this framework, we explore a broad range of economically feasible greenhouse gas scenarios from the integrated assessment community14, 15, 16, 17 to determine the likelihood of meeting a combination of specific global and regional targets under various assumptions. For any given likelihood of meeting a set of such targets, the allowable cumulative emissions are greatly reduced from those inferred from the temperature target alone. Therefore, temperature targets alone are unable to comprehensively limit the risks from anthropogenic emissions.