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31.
Václav Šlouf Marcel Fuciman Silke Johanning Eckhard Hofmann Harry A. Frank Tomáš Polívka 《Photosynthesis research》2013,117(1-3):257-265
The major light-harvesting complex of Amphidinium (A.) carterae, chlorophyll-a–chlorophyll-c 2–peridinin–protein complex (acpPC), was studied using ultrafast pump-probe spectroscopy at low temperature (60 K). An efficient peridinin–chlorophyll-a energy transfer was observed. The stimulated emission signal monitored in the near-infrared spectral region was stronger when redder part of peridinin pool was excited, indicating that these peridinins have the S1/ICT (intramolecular charge-transfer) state with significant charge-transfer character. This may lead to enhanced energy transfer efficiency from “red” peridinins to chlorophyll-a. Contrary to the water-soluble antenna of A. carterae, peridinin–chlorophyll-a protein, the energy transfer rates in acpPC were slower under low-temperature conditions. This fact underscores the influence of the protein environment on the excited-state dynamics of pigments and/or the specificity of organization of the two pigment–protein complexes. 相似文献
32.
Labeled nitrogen (15?N) was applied to a soil-based substrate in order to study the uptake of N by Glomus intraradices extraradical mycelium (ERM) from different mineral N (NO 3 ? vs. NH 4 + ) sources and the subsequent transfer to cowpea plants. Fungal compartments (FCs) were placed within the plant growth substrate to simulate soil patches containing root-inaccessible, but mycorrhiza-accessible, N. The fungus was able to take up both N-forms, NO 3 ? and NH 4 + . However, the amount of N transferred from the FC to the plant was higher when NO 3 ? was applied to the FC. In contrast, analysis of ERM harvested from the FC showed a higher 15?N enrichment when the FC was supplied with 15NH 4 + compared with 15NO 3 ? . The 15?N shoot/root ratio of plants supplied with 15NO 3 ? was much higher than that of plants supplied with 15NH 4 + , indicative of a faster transfer of 15NO 3 ? from the root to the shoot and a higher accumulation of 15NH 4 + in the root and/or intraradical mycelium. It is concluded that hyphae of the arbuscular mycorrhizal fungus may absorb NH 4 + preferentially over NO 3 ? but that export of N from the hyphae to the root and shoot may be greater following NO 3 ? uptake. The need for NH 4 + to be assimilated into organically bound N prior to transport into the plant is discussed. 相似文献
33.
Tomá? Venit Rastislav Dzijak Al?běta Kalendová Michal Kahle Jana Roho?ková Volker Schmidt Thomas Rülicke Birgit Rathkolb Wolfgang Hans Alexander Bohla Oliver Eickelberg Tobias Stoeger Eckhard Wolf Ali ?nder Yildirim Valérie Gailus-Durner Helmut Fuchs Martin Hrabě de Angelis Pavel Hozák 《PloS one》2013,8(4)
34.
Martin Neumann Ebru Coskun Lars Fransecky Liliana H. Mochmann Isabelle Bartram Nasrin Farhadi Sartangi Sandra Heesch Nicola G?kbuget Stefan Schwartz Christian Brandts Cornelia Schlee Rainer Haas Ulrich Dührsen Martin Griesshammer Hartmut D?hner Gerhard Ehninger Thomas Burmeister Olga Blau Eckhard Thiel Dieter Hoelzer Wolf-Karsten Hofmann Claudia D. Baldus 《PloS one》2013,8(1)
Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) has been identified as high-risk subgroup of acute T-lymphoblastic leukemia (T-ALL) with a high rate of FLT3-mutations in adults. To unravel the underlying pathomechanisms and the clinical course we assessed molecular alterations and clinical characteristics in a large cohort of ETP-ALL (n = 68) in comparison to non-ETP T-ALL adult patients. Interestingly, we found a high rate of FLT3-mutations in ETP-ALL samples (n = 24, 35%). Furthermore, FLT3 mutated ETP-ALL was characterized by a specific immunophenotype (CD2+/CD5-/CD13+/CD33-), a distinct gene expression pattern (aberrant expression of IGFBP7, WT1, GATA3) and mutational status (absence of NOTCH1 mutations and a low frequency, 21%, of clonal TCR rearrangements). The observed low GATA3 expression and high WT1 expression in combination with lack of NOTCH1 mutations and a low rate of TCR rearrangements point to a leukemic transformation at the pluripotent prothymocyte stage in FLT3 mutated ETP-ALL. The clinical outcome in ETP-ALL patients was poor, but encouraging in those patients with allogeneic stem cell transplantation (3-year OS: 74%). To further explore the efficacy of targeted therapies, we demonstrate that T-ALL cell lines transfected with FLT3 expression constructs were particularly sensitive to tyrosine kinase inhibitors. In conclusion, FLT3 mutated ETP-ALL defines a molecular distinct stem cell like leukemic subtype. These data warrant clinical studies with the implementation of FLT3 inhibitors in addition to early allogeneic stem cell transplantation for this high risk subgroup. 相似文献
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36.
The Tau/A152T mutation,a risk factor for frontotemporal‐spectrum disorders,leads to NR2B receptor‐mediated excitotoxicity 下载免费PDF全文
Astrid Sydow Frank JA Dennissen Zuzana Siskova Eckhard Mandelkow Eva‐Maria Mandelkow 《EMBO reports》2016,17(4):552-569
We report on a novel transgenic mouse model expressing human full‐length Tau with the Tau mutation A152T (hTauAT), a risk factor for FTD‐spectrum disorders including PSP and CBD. Brain neurons reveal pathological Tau conformation, hyperphosphorylation, mis‐sorting, aggregation, neuronal degeneration, and progressive loss, most prominently in area CA3 of the hippocampus. The mossy fiber pathway shows enhanced basal synaptic transmission without changes in short‐ or long‐term plasticity. In organotypic hippocampal slices, extracellular glutamate increases early above control levels, followed by a rise in neurotoxicity. These changes are normalized by inhibiting neurotransmitter release or by blocking voltage‐gated sodium channels. CA3 neurons show elevated intracellular calcium during rest and after activity induction which is sensitive to NR2B antagonizing drugs, demonstrating a pivotal role of extrasynaptic NMDA receptors. Slices show pronounced epileptiform activity and axonal sprouting of mossy fibers. Excitotoxic neuronal death is ameliorated by ceftriaxone, which stimulates astrocytic glutamate uptake via the transporter EAAT2/GLT1. In summary, hTauAT causes excitotoxicity mediated by NR2B‐containing NMDA receptors due to enhanced extracellular glutamate. 相似文献
37.
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
38.
39.
A new class of galactooligosaccharides has been identified from the terrestrial cyanobacterium Nostoc commune by MS and NMR techniques. These consist of beta-D-galactofuranosyl-(1-->6)-[beta-D-galactofuranosyl-(1-->6)]n-beta-d-1,4-anhydrogalactitols with n ranging from 2 to 8, corresponding to compounds designated 1 through 7. In total these saccharides amounted to approximately 0.35% of the dry thallus of N. commune, while in several other cyanobacteria they were not detected. Possibly they play some role in protection from damage by heat and desiccation as suggested by experiments with heterologous systems. For example, phosphoglucomutase (EC 2.7.5.1) from rabbit muscle was protected against heat inactivation by these oligosaccharides, and alpha-amylase (EC 3.2.1.1) from porcine pancreas by the oligosaccharides 6 and 7. The homologues of lower molecular mass, however, enhanced heat sensitivity of alpha-amylase. The viability of Escherichia coli was completely abolished by desiccation, whereas in the presence of 4 survival rates were approximately 50% of controls not subjected to desiccation. The newly identified saccharides are compared with known galactofuranose-based oligo- and polysaccharides and possible biological functions of them are discussed. 相似文献
40.
A genetic screen for modifiers of the delta1-dependent notch signaling function in the mouse 下载免费PDF全文
Rubio-Aliaga I Soewarto D Wagner S Klaften M Fuchs H Kalaydjiev S Busch DH Klempt M Rathkolb B Wolf E Abe K Zeiser S Przemeck GK Beckers J de Angelis MH 《Genetics》2007,175(3):1451-1463
The Notch signaling pathway is an evolutionarily conserved transduction pathway involved in embryonic patterning and regulation of cell fates during development. Recent studies have demonstrated that this pathway is integral to a complex system of interactions, which are also involved in distinct human diseases. Delta1 is one of the known ligands of the Notch receptors. Mice homozygous for a loss-of-function allele of the Delta1 gene Dll1(lacZ/lacZ) die during embryonic development. Here, we present the results of two phenotype-driven modifier screens. Heterozygous Dll1(lacZ) knockout animals were crossed with ENU-mutagenized mice and screened for dysmorphological, clinical chemical, and immunological variants that are dependent on the Delta1 loss-of-function allele. First, we show that mutagenized heterozygous Dll1(lacZ) offspring have reduced body weight and altered specific clinical chemical parameters, including changes in metabolites and electrolytes relevant for kidney function. In our mutagenesis screen we have successfully generated 35 new mutant lines. Of major interest are 7 mutant lines that exhibit a Dll1(lacZ/+)-dependent phenotype. These mutant mouse lines provide excellent in vivo tools for studying the role of Notch signaling in kidney and liver function, cholesterol and iron metabolism, cell-fate decisions, and during maturation of T cells in the immune system. 相似文献