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111.
Justus Masa Stefan Piontek Patrick Wilde Hendrik Antoni Till Eckhard Yen‐Ting Chen Martin Muhler Ulf‐Peter Apfel Wolfgang Schuhmann 《Liver Transplantation》2019,9(26)
Breakthroughs toward effective water‐splitting electrocatalysts for mass hydrogen production will necessitate material design strategies based on unexplored material chemistries. Herein, Ni‐metalloid (B, Si, P, As, Te) alloys are reported as an emergent class of highly promising electrocatalysts for the oxygen evolution reaction (OER) and insight is offered into the origin of activity enhancement on the premise of the surface electronic structure, the OER activation energy, influence of the guest metalloid elements on the lattice structure of the host metal (Ni), and surface‐oxidized metalloid oxoanions. The metalloids modify the lattice structure of Ni, causing changes in the nearest Ni–Ni interatomic distance (dNi–Ni). The activation energy Ea scales with dNi–Ni indicating an apparent dependence of the OER activity on lattice properties. During the OER, surface Ni atoms are oxidized to nickel oxyhydroxide, which is the active state of the catalyst, meanwhile, the surface metalloids are oxidized to the corresponding oxoanions that affect the interfacial electrode/electrolyte properties and hence the adsorption/desorption interaction energies of the reacting species. 相似文献
112.
Sybryn L. Maes Michael P. Perring Margot Vanhellemont Leen Depauw Jan Van den Bulcke Guntis Brmelis Jrg Brunet Guillaume Decocq Jan den Ouden Werner Hrdtle Radim Hdl Thilo Heinken Steffi Heinrichs Bogdan Jaroszewicz Martin Kopecký Frantiek Mli Monika Wulf Kris Verheyen 《Global Change Biology》2019,25(1):201-217
Forecasting the growth of tree species to future environmental changes requires a better understanding of its determinants. Tree growth is known to respond to global‐change drivers such as climate change or atmospheric deposition, as well as to local land‐use drivers such as forest management. Yet, large geographical scale studies examining interactive growth responses to multiple global‐change drivers are relatively scarce and rarely consider management effects. Here, we assessed the interactive effects of three global‐change drivers (temperature, precipitation and nitrogen deposition) on individual tree growth of three study species (Quercus robur/petraea, Fagus sylvatica and Fraxinus excelsior). We sampled trees along spatial environmental gradients across Europe and accounted for the effects of management for Quercus. We collected increment cores from 267 trees distributed over 151 plots in 19 forest regions and characterized their neighbouring environment to take into account potentially confounding factors such as tree size, competition, soil conditions and elevation. We demonstrate that growth responds interactively to global‐change drivers, with species‐specific sensitivities to the combined factors. Simultaneously high levels of precipitation and deposition benefited Fraxinus, but negatively affected Quercus’ growth, highlighting species‐specific interactive tree growth responses to combined drivers. For Fagus, a stronger growth response to higher temperatures was found when precipitation was also higher, illustrating the potential negative effects of drought stress under warming for this species. Furthermore, we show that past forest management can modulate the effects of changing temperatures on Quercus’ growth; individuals in plots with a coppicing history showed stronger growth responses to higher temperatures. Overall, our findings highlight how tree growth can be interactively determined by global‐change drivers, and how these growth responses might be modulated by past forest management. By showing future growth changes for scenarios of environmental change, we stress the importance of considering multiple drivers, including past management and their interactions, when predicting tree growth. 相似文献
113.
Ray Dybzinski Angelo Kelvakis John McCabe Samantha Panock Kanyarak Anuchitlertchon Leah Vasarhelyi M. Luke McCormack Gordon G. McNickle Hendrik Poorter Clare Trinder Caroline E. Farrior 《Global Change Biology》2019,25(3):885-899
Understanding the effects of global change in terrestrial communities requires an understanding of how limiting resources interact with plant traits to affect productivity. Here, we focus on nitrogen and ask whether plant community nitrogen uptake rate is determined (a) by nitrogen availability alone or (b) by the product of nitrogen availability and fine‐root mass. Surprisingly, this is not empirically resolved. We performed controlled microcosm experiments and reanalyzed published pot experiments and field data to determine the relationship between community‐level nitrogen uptake rate, nitrogen availability, and fine‐root mass for 46 unique combinations of species, nitrogen levels, and growing conditions. We found that plant community nitrogen uptake rate was unaffected by fine‐root mass in 63% of cases and saturated with fine‐root mass in 29% of cases (92% in total). In contrast, plant community nitrogen uptake rate was clearly affected by nitrogen availability. The results support the idea that although plants may over‐proliferate fine roots for individual‐level competition, it comes without an increase in community‐level nitrogen uptake. The results have implications for the mechanisms included in coupled carbon‐nitrogen terrestrial biosphere models (CN‐TBMs) and are consistent with CN‐TBMs that operate above the individual scale and omit fine‐root mass in equations of nitrogen uptake rate but inconsistent with the majority of CN‐TBMs, which operate above the individual scale and include fine‐root mass in equations of nitrogen uptake rate. For the much smaller number of CN‐TBMs that explicitly model individual‐based belowground competition for nitrogen, the results suggest that the relative (not absolute) fine‐root mass of competing individuals should be included in the equations that determine individual‐level nitrogen uptake rates. By providing empirical data to support the assumptions used in CN‐TBMs, we put their global climate change predictions on firmer ground. 相似文献
114.
115.
Britt Paulsen Kim Alex Fredriksen Dirk Petersen Louis Maes An Matheeussen Ali-Oddin Naemi Anne Aamdal Scheie Roger Simm Rui Ma Baojie Wan Scott Franzblau Lise-Lotte Gundersen 《Bioorganic & medicinal chemistry》2019,27(4):620-629
(+)-N6-Hydroxyagelasine D, the enantiomer of the proposed structure of (?)-ageloxime D, as well as N6-hydroxyagelasine analogs were synthesized by selective N-7 alkylation of N6-[tert-butyl(dimethyl)silyloxy]-9-methyl-9H-purin-6-amine in order to install the terpenoid side chain, followed by fluoride mediated removal of the TBDMS-protecting group. N6-Hydroxyagelasine D and the analog carrying a geranylgeranyl side chain displayed profound antimicrobial activities against several pathogenic bacteria and protozoa and inhibited bacterial biofilm formation. However these compounds were also toxic towards mammalian fibroblast cells (MRC-5). The spectral data of N6-hydroxyagelasine D did not match those reported for ageloxime D before. Hence, a revised structure of ageloxime D was proposed. Basic hydrolysis of agelasine D gave (+)-N-[4-amino-6-(methylamino)pyrimidin-5-yl]-N-copalylformamide, a compound with spectral data in full agreement with those reported for (?)-ageloxime D. 相似文献
116.
Hendrik Koliwer‐Brandl Paulina Knobloch Caroline Barisch Amanda Welin Nabil Hanna Thierry Soldati Hubert Hilbi 《Cellular microbiology》2019,21(6)
The causative agent of tuberculosis, Mycobacterium tuberculosis, and its close relative Mycobacterium marinum manipulate phagocytic host cells, thereby creating a replication‐permissive compartment termed the Mycobacterium‐containing vacuole (MCV). The phosphoinositide (PI) lipid pattern is a crucial determinant of MCV formation and is targeted by mycobacterial PI phosphatases. In this study, we establish an efficient phage transduction protocol to construct defined M. marinum deletion mutants lacking one or three phosphatases, PtpA, PtpB, and/or SapM. These strains were defective for intracellular replication in macrophages and amoebae, and the growth defect was complemented by the corresponding plasmid‐borne genes. Fluorescence microscopy of M. marinum‐infected Dictyostelium discoideum revealed that MCVs harbouring mycobacteria lacking PtpA, SapM, or all three phosphatases accumulate significantly more phosphatidylinositol‐3‐phosphate (PtdIns3P) compared with MCVs containing the parental strain. Moreover, PtpA reduced MCV acidification by blocking the recruitment of the V‐ATPase, and all three phosphatases promoted bacterial escape from the pathogen vacuole to the cytoplasm. In summary, the secreted M. marinum phosphatases PtpA, PtpB, and SapM determine the MCV PI pattern, compartment acidification, and phagosomal escape. 相似文献
117.
118.
Oosterveen T Coudreuse DY Yang PT Fraser E Bergsma J Dale TC Korswagen HC 《Developmental biology》2007,308(2):438-448
Axin is a central component of the canonical Wnt signaling pathway that interacts with the adenomatous polyposis coli protein APC and the kinase GSK3beta to downregulate the effector beta-catenin. In the nematode Caenorhabditis elegans, canonical Wnt signaling is negatively regulated by the highly divergent Axin ortholog PRY-1. Mutation of pry-1 leads to constitutive activation of BAR-1/beta-catenin-dependent Wnt signaling and results in a range of developmental defects. The pry-1 null phenotype is however not fully penetrant, indicating that additional factors may partially compensate for PRY-1 function. Here, we report the cloning and functional analysis of a second Axin-like protein, which we named AXL-1. We show that despite considerable sequence divergence with PRY-1 and other Axin family members, AXL-1 is a functional Axin ortholog. AXL-1 functions redundantly with PRY-1 in negatively regulating BAR-1/beta-catenin signaling in the developing vulva and the Q neuroblast lineage. In addition, AXL-1 functions independently of PRY-1 in negatively regulating canonical Wnt signaling during excretory cell development. In contrast to vertebrate Axin and the related protein Conductin, AXL-1 and PRY-1 are not functionally equivalent. We conclude that Axin function in C. elegans is divided over two different Axin orthologs that have specific functions in negatively regulating canonical Wnt signaling. 相似文献
119.
Chalajour F Treede H Gehling UM Ebrahimnejad A Boehm DH Riemer RK Ergun S Reichenspurner H 《Experimental cell research》2007,313(11):2326-2335
Recent data suggest that angiogenesis plays an important role in the pathogenesis of valvular disease. However, the cellular mechanisms underlying this process remain unknown. This study aimed at identifying and characterizing the cellular components responsible for pathological neovascularization in calcific aortic valves (CAV). Immunohistochemical analysis of uncultured CAV tissues revealed that smooth muscle alpha-actin (alpha-SMA)-positive cells, which coexpressed Tie-2 and vascular endothelial growth factor receptor-2 (VEGFR-2), can be identified prior to the initiation of capillary-like tube formation. In a second step, leaflets of CAV and non-calcific aortic valves (NCAV) were cultured and the cells involved in capillary-like tube formation were isolated. The majority of these cells displayed the same phenotype as non-cultured cells identified in CAV tissues, i.e., expression of alpha-SMA, Tie-2, and VEGFR-2. In comparison to cells isolated from cultures of NCAV leaflets, these cells showed enhanced angiogenic activity as demonstrated by migration and tube assays. The coexpression of VEGFR-2 and Tie-2 together with alpha-SMA suggests both endothelial and mesenchymal properties of the angiogenically activated cells involved in valvular neovascularization. Hence, our findings might provide new insights into the process of pathological angiogenesis in cardiac valves. 相似文献
120.