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981.
982.
Forecasted coral reef decline in marine biodiversity hotspots under climate change 总被引:1,自引:0,他引:1
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Patrice Descombes Mary S. Wisz Fabien Leprieur Valerianio Parravicini Christian Heine Steffen M. Olsen Didier Swingedouw Michel Kulbicki David Mouillot Loïc Pellissier 《Global Change Biology》2015,21(7):2479-2487
Coral bleaching events threaten coral reef habitats globally and cause severe declines of local biodiversity and productivity. Related to high sea surface temperatures (SST), bleaching events are expected to increase as a consequence of future global warming. However, response to climate change is still uncertain as future low‐latitude climatic conditions have no present‐day analogue. Sea surface temperatures during the Eocene epoch were warmer than forecasted changes for the coming century, and distributions of corals during the Eocene may help to inform models forecasting the future of coral reefs. We coupled contemporary and Eocene coral occurrences with information on their respective climatic conditions to model the thermal niche of coral reefs and its potential response to projected climate change. We found that under the RCP8.5 climate change scenario, the global suitability for coral reefs may increase up to 16% by 2100, mostly due to improved suitability of higher latitudes. In contrast, in its current range, coral reef suitability may decrease up to 46% by 2100. Reduction in thermal suitability will be most severe in biodiversity hotspots, especially in the Indo‐Australian Archipelago. Our results suggest that many contemporary hotspots for coral reefs, including those that have been refugia in the past, spatially mismatch with future suitable areas for coral reefs posing challenges to conservation actions under climate change. 相似文献
983.
Synthesis and Characterization of High‐Energy,High‐Power Spinel‐Layered Composite Cathode Materials for Lithium‐Ion Batteries
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Steffen Krueger Vassilios Siozios Jie Li Sascha Nowak Martin Winter 《Liver Transplantation》2015,5(5)
Spinel‐layered composites, where a high‐voltage spinel is incorporated in a layered lithium‐rich (Li‐rich) cathode material with a nominal composition x{0.6Li2MnO3 · 0.4[LiCo0.333Mn0.333Ni0.333]O2} · (1 – x) Li[Ni0.5Mn1.5]O4 (x = 0, 0.3, 0.5, 0.7, 1) are synthesized via a hydroxide assisted coprecipitation route to generate high‐energy, high‐power cathode materials for Li‐ion batteries. X‐ray diffraction patterns and the cyclic voltammetry investigations confirm the presence of both the parent components in the composites. The electrochemical investigations performed within a wide potential window show an increased structural stability of the spinel component when incorporated into the composite environment. All the composite materials exhibit initial discharge capacities >200 mAh g–1. The compositions with x = 0.5 and 0.7 show excellent cycling stability among the investigated materials. Moreover, the first cycle Coulombic efficiency achieve a dramatic improvement with the incorporation of the spinel component. More notably, the composite materials with increased spinel component exhibit superior rate capability compared with the parent Li‐rich material especially together with the highest capacity retention for x = 0.5 composition, making this as the optimal high‐energy high‐power material. The mechanisms involved in the symbiotic relationship of the spinel and layered Li‐rich components in the above composites are discussed. 相似文献
984.
Nickel D Busch M Mayer D Hagemann B Knoll V Stenger S 《Journal of immunology (Baltimore, Md. : 1950)》2012,188(8):4001-4007
Low oxygen tension is a metabolic hallmark of chronic infection. To investigate the influence of hypoxia on macrophage biology, we analyzed the interaction between the intracellular pathogen Mycobacterium tuberculosis and primary human macrophages. Although the metabolic activity of extracellular M. tuberculosis was reduced at oxygen levels between 0.5 and 10%, the bacilli remained viable throughout the 4 d of culture. Phagocytosis of virulent M. tuberculosis and the pathogen-induced release of inflammatory cytokines by macrophages were not affected by oxygen levels as low as 1%. However, we detected the upregulation of an antimicrobial effector pathway mediated by the vitamin D receptor and human β defensin 2. This finding was functionally relevant, because intracellular mycobacterial growth was inhibited by 58 ± 8% at 1% O(2). We conclude that a hypoxic microenvironment, which is characteristic of infected tissue, supports the efficacy of antimicrobial immunity, in part by the upregulation of the antimicrobial peptide human β defensin 2. 相似文献
985.
Frédéric H. Vaillancourt Martine Brault Louise Pilote Nathalie Uyttersprot Elias T. Gaillard James H. Stoltz Brian L. Knight Lynn Pantages Mary McFarland Steffen Breitfelder Tim T. Chiu Louiza Mahrouche Anne-Marie Faucher Mireille Cartier Michael G. Cordingley Richard C. Bethell Huiping Jiang Peter W. White George Kukolj 《Journal of virology》2012,86(21):11595-11607
Phosphatidylinositol-4-kinase IIIα (PI4KIIIα) is an essential host cell factor for hepatitis C virus (HCV) replication. An N-terminally truncated 130-kDa form was used to reconstitute an in vitro biochemical lipid kinase assay that was optimized for small-molecule compound screening and identified potent and specific inhibitors. Cell culture studies with PI4KIIIα inhibitors demonstrated that the kinase activity was essential for HCV RNA replication. Two PI4KIIIα inhibitors were used to select cell lines harboring HCV replicon mutants with a 20-fold loss in sensitivity to the compounds. Reverse genetic mapping isolated an NS4B-NS5A segment that rescued HCV RNA replication in PIK4IIIα-deficient cells. HCV RNA replication occurs on specialized membranous webs, and this study with PIK4IIIα inhibitor-resistant mutants provides a genetic link between NS4B/NS5A functions and PI4-phosphate lipid metabolism. A comprehensive assessment of PI4KIIIα as a drug target included its evaluation for pharmacologic intervention in vivo through conditional transgenic murine lines that mimic target-specific inhibition in adult mice. Homozygotes that induce a knockout of the kinase domain or knock in a single amino acid substitution, kinase-defective PI4KIIIα, displayed a lethal phenotype with a fairly widespread mucosal epithelial degeneration of the gastrointestinal tract. This essential host physiologic role raises doubt about the pursuit of PI4KIIIα inhibitors for treatment of chronic HCV infection. 相似文献
986.
Joern E. Schmitz Zhong-Min Ma Emily A. Hagan Andrew B. Wilks Kathryn L. Furr Caitlyn H. Linde Roland C. Zahn Jason M. Brenchley Christopher J. Miller Sallie R. Permar 《Journal of virology》2012,86(20):11380-11385
Simian immunodeficiency virus (SIV) infection of natural hosts is characterized by nonpathogenic chronic viremia, maintenance of gastrointestinal epithelial barrier integrity, and low numbers of target cells. Assessment of cell-associated virus load in T cell subsets in multiple anatomic compartments of chronically SIV-infected sabeus African green monkeys (AGMs) revealed that gastrointestinal memory CD4+ T lymphocytes are a major source of cell-associated virus and a significant contributor to SIV viremia in AGMs. 相似文献
987.
Yang F Wang Q Schmitz G Müller D Theres K 《The Plant journal : for cell and molecular biology》2012,71(1):61-70
During post-embryonic shoot development, new meristems are initiated in the axils of leaves. They produce secondary axes of growth that determine morphological plasticity and reproductive efficiency in higher plants. In this study, we describe the role of the bHLH-protein-encoding Arabidopsis gene REGULATOR OF AXILLARY MERISTEM FORMATION (ROX), which is the ortholog of the branching regulators LAX PANICLE1 (LAX1) in rice and barren stalk1 (ba1) in maize. rox mutants display compromised axillary bud formation during vegetative shoot development, and combination of rox mutants with mutations in RAX1 and LAS, two key regulators of axillary meristem initiation, enhances their branching defects. In contrast to lax1 and ba1, flower development is unaffected in rox mutants. Over-expression of ROX leads to formation of accessory side shoots. ROX mRNA accumulates at the adaxial boundary of leaf and flower primordia. However, in the vegetative phase, axillary meristems initiate after ROX expression has terminated, suggesting an indirect role for ROX in meristem formation. During vegetative development, ROX expression is dependent on RAX1 and LAS activity, and all three genes act in concert to modulate axillary meristem formation. 相似文献
988.
Moritz S Stöckle F Ortmeier C Schmitz H Rodríguez-Esteban G Key G Gentile L 《The International journal of developmental biology》2012,56(1-3):117-125
The planarian adult stem cell (pASC) population has a specific molecular signature and can be easily visualized and isolated by flow cytometry. However, the lack of antibodies against specific surface markers for planarian cells prevents a deeper analysis of specific cell populations. Here, if we describe the results of the immunoscreening of pASC plasma membrane proteins (PMPs). A novel papain-based method for planarian cell dissociation enabling both high yield and improved cell viability was used to generate single cell preparations for PMP purification. PMPs were used for intraperitoneal immunization of mice and thus about 1000 hybridoma clones were generated and screened. Supernatants collected from the hybridoma clones were first screened by ELISA and then by live immuno-staining. About half of these supernatants stained all the planarian cells, whereas the other half specifically labeled a subfraction thereof. A detailed analysis of two hybridoma supernatants revealed that large subfractions of the X1, X2 and Xin populations differentially express specific membrane markers. Quantitative PCR data disclosed a correlation between the immunostaining results and the expression of markers of the early and late progeny, also for those pASCs in the S/G2/M phase of the cell cycle (X1 population). Thus, about two thirds of the cycling pASCs showed a specific membrane signature coupled with the expression of markers hitherto considered to be restricted to differentiating, post-mitotic progeny. In summary, a library of 66 monoclonal antibodies against planarian PMPs was generated. The analysis of two of the clones generated revealed that a subset of cells of the X1 population expresses early and late progeny markers, which might indicate that these cells are committed while still proliferating. The findings demonstrate the usefulness of our PMP antibody library for planarian research. 相似文献
989.
Nadia S. Santini Nele Schmitz Catherine E. Lovelock 《Trees - Structure and Function》2012,26(5):1555-1563
Wood density is an important plant trait that influences a range of ecological processes, including resistance to damage and growth rates. Wood density is highly dependent on anatomical characteristics associated with the conductive tissue of trees (xylem and phloem) and the fibre matrix in which they occur. Here, we investigated variation in the wood density of the widespread mangrove species Avicennia marina in the Exmouth Gulf in Western Australia and in the Firth of Thames in New Zealand. We assessed how variation in xylem vessel size, fibre wall thickness and proportion of phloem within the wood contributed to variation in wood density and how these characteristics were linked to growth rates. We found the wood density of A. marina to be higher in Western Australia than in New Zealand and to be higher in taller seaward fringing trees than in scrub trees growing high in the intertidal. At the cellular level, high wood density was associated with large xylem vessels and thick fibre walls. Additionally, wood density increased with decreasing proportions of phloem per growth layer of wood. Tree growth rates were positively correlated with xylem vessel size and wood density. We conclude that A. marina can have large xylem vessel sizes and high growth rates while still maintaining high wood density because of the abundance and thickness of fibres in which vessels are found. 相似文献
990.
Matzke A Churakov G Berkes P Arms EM Kelsey D Brosius J Kriegs JO Schmitz J 《Molecular biology and evolution》2012,29(6):1497-1501
More than 150 Ma, the avian lineage separated from that of other dinosaurs and later diversified into the more than 10,000 species extant today. The early neoavian bird radiations most likely occurred in the late Cretaceous (more than 65 Ma) but left behind few if any molecular signals of their archaic evolutionary past. Retroposed elements, once established in an ancestral population, are highly valuable, virtually homoplasy-free markers of species evolution; after applying stringent orthology criteria, their phylogenetically informative presence/absence patterns are free of random noise and independent of evolutionary rate or nucleotide composition effects. We screened for early neoavian orthologous retroposon insertions and identified six markers with conflicting presence/absence patterns, whereas six additional retroposons established before or after the presumed major neoavian radiation show consistent phylogenetic patterns. The exceptionally frequent conflicting retroposon presence/absence patterns of neoavian orders are strong indicators of an extensive incomplete lineage sorting era, potentially induced by an early rapid successive speciation of ancestral Neoaves. 相似文献