TY - JOUR A1 - Schurr, Frank Martin A1 - Dean, W. R. J. A1 - Milton, Sue J. A1 - Jeltsch, Florian T1 - A conceptual model linking demography of the shrub species Grewia flava to the dynamics of Kalahari savannas N2 - Environmental heterogeneity is a major determinant of plant population dynamics. In semi-arid Kalahari savannas, heterogeneity is created by savanna structure, i.e. by the spatial arrangement and temporal dynamics of woody plant and open grassland microsites. We formulate a conceptual model describing the effects of savanna dynamics on the population dynamics of the animal-dispersed shrub Grewia flava. From empirical results we derive model rules describing effects of savanna structure on several processes in Grewia's life cycle. By formulating the model, we summarise existing information on Grewia demography and identify gaps in this knowledge. Despite a number of such gaps, the model can be used to make certain quantitative predictions. As an example, we apply the model to investigate the role of seed dispersal in Grewia encroachment on rangelands. Model results show that cattle promote encroachment by depositing substantial numbers of seeds in open areas, where Grewia is otherwise dispersal-limited. Finally, we draw some general conclusions about Grewia's life history and population dynamics. Under natural conditions, concentrated seed deposition under woody plants appears to be a key process causing the observed association between Grewia and other woody plants. Furthermore, low rates of recruitment and high adult survival result in slow-motion dynamics of Grewia populations. As a consequence, Grewia populations interact with savanna dynamics on long temporal and short to intermediate spatial scales. Y1 - 2004 ER - TY - JOUR A1 - Chapman, Eric M. A1 - Lant, Benjamin A1 - Ohashi, Yota A1 - Yu, Bin A1 - Schertzberg, Michael A1 - Go, Christopher A1 - Dogra, Deepika A1 - Koskimaki, Janne A1 - Girard, Romuald A1 - Li, Yan A1 - Fraser, Andrew G. A1 - Awad, Issam A. A1 - Abdelilah-Seyfried, Salim A1 - Gingras, Anne-Claude A1 - Derry, William Brent T1 - A conserved CCM complex promotes apoptosis non-autonomously by regulating zinc homeostasis JF - Nature Communications N2 - Apoptotic death of cells damaged by genotoxic stress requires regulatory input from surrounding tissues. The C. elegans scaffold protein KRI-1, ortholog of mammalian KRIT1/CCM1, permits DNA damage-induced apoptosis of cells in the germline by an unknown cell non-autonomous mechanism. We reveal that KRI-1 exists in a complex with CCM-2 in the intestine to negatively regulate the ERK-5/MAPK pathway. This allows the KLF-3 transcription factor to facilitate expression of the SLC39 zinc transporter gene zipt-2.3, which functions to sequester zinc in the intestine. Ablation of KRI-1 results in reduced zinc sequestration in the intestine, inhibition of IR-induced MPK-1/ERK1 activation, and apoptosis in the germline. Zinc localization is also perturbed in the vasculature of krit1(-/-) zebrafish, and SLC39 zinc transporters are mis-expressed in Cerebral Cavernous Malformations (CCM) patient tissues. This study provides new insights into the regulation of apoptosis by cross-tissue communication, and suggests a link between zinc localization and CCM disease. Y1 - 2019 U6 - https://doi.org/10.1038/s41467-019-09829-z SN - 2041-1723 VL - 10 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Wolff, Martin A1 - Gast, Klaus A1 - Evers, Andreas A1 - Kurz, Michael A1 - Pfeiffer-Marek, Stefania A1 - Schüler, Anja A1 - Seckler, Robert A1 - Thalhammer, Anja T1 - A Conserved Hydrophobic Moiety and Helix-Helix Interactions Drive the Self-Assembly of the Incretin Analog Exendin-4 JF - Biomolecules N2 - Exendin-4 is a pharmaceutical peptide used in the control of insulin secretion. Structural information on exendin-4 and related peptides especially on the level of quaternary structure is scarce. We present the first published association equilibria of exendin-4 directly measured by static and dynamic light scattering. We show that exendin-4 oligomerization is pH dependent and that these oligomers are of low compactness. We relate our experimental results to a structural hypothesis to describe molecular details of exendin-4 oligomers. Discussion of the validity of this hypothesis is based on NMR, circular dichroism and fluorescence spectroscopy, and light scattering data on exendin-4 and a set of exendin-4 derived peptides. The essential forces driving oligomerization of exendin-4 are helix–helix interactions and interactions of a conserved hydrophobic moiety. Our structural hypothesis suggests that key interactions of exendin-4 monomers in the experimentally supported trimer take place between a defined helical segment and a hydrophobic triangle constituted by the Phe22 residues of the three monomeric subunits. Our data rationalize that Val19 might function as an anchor in the N-terminus of the interacting helix-region and that Trp25 is partially shielded in the oligomer by C-terminal amino acids of the same monomer. Our structural hypothesis suggests that the Trp25 residues do not interact with each other, but with C-terminal Pro residues of their own monomers. KW - biophysics KW - diabetes KW - peptides KW - oligomerization KW - conformational change KW - molecular modeling KW - static and dynamic light scattering KW - spectroscopy Y1 - 2021 U6 - https://doi.org/10.3390/biom11091305 SN - 2218-273X VL - 11 IS - 9 PB - MDPI CY - Basel ER - TY - JOUR A1 - Luetkecosmann, Steffi A1 - Faupel, Thomas A1 - Porstmann, Silvia A1 - Porstmann, Tomas A1 - Micheel, Burkhard A1 - Hanack, Katja T1 - A cross-reactive monoclonal antibody as universal detection antibody in autoantibody diagnostic assays JF - Clinica chimica acta N2 - Diagnostics of Autoimmune Diseases involve screening of patient samples for containing autoantibodies against various antigens. To ensure quality of diagnostic assays a calibrator is needed in each assay system. Different calibrators as recombinant human monoclonal antibodies as well as chimeric antibodies against the autoantigens of interest are described. A less cost-intensive and also more representative possibility covering different targets on the antigens is the utilization of polyclonal sera from other species. Nevertheless, the detection of human autoantibodies as well as the calibration reagent containing antibodies from other species in one assay constitutes a challenge in terms of assay calibration. We therefore developed a cross-reactive monoclonal antibody which binds human as well as rabbit sera with similar affinities in the nanomolar range. We tested our monoclonal antibody S38CD11B12 successfully in the commercial Serazym (R) Anti-Cardiolipin-beta 2-GPI IgG/IgM assay and could thereby prove the eligibility of S38CD11B12 as detection antibody in autoimmune diagnostic assays using rabbit derived sera as reference material. KW - Monoclonal antibody KW - Detection KW - Autoimmune diagnostics KW - Cross reactivity KW - Assay calibration Y1 - 2019 U6 - https://doi.org/10.1016/j.cca.2019.09.003 SN - 0009-8981 SN - 1873-3492 VL - 499 SP - 87 EP - 92 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Samuel, Prinson P. A1 - Horn, Sebastian A1 - Döring, Alexander A1 - Havelius, Kajsa G. V. A1 - Reschke, Stefan A1 - Leimkühler, Silke A1 - Haumann, Michael A1 - Schulzke, Carola T1 - A Crystallographic and Mo K-Edge XAS Study of Molybdenum Oxo Bis-,Mono-, and Non-Dithiolene Complexes - First-Sphere Coordination Geometry and Noninnocence of Ligands JF - European journal of inorganic chemistry : a journal of ChemPubSoc Europe N2 - Ten square-based pyramidal molybdenum complexes with different sulfur donor ligands, that is, a variety of dithiolenes and sulfides, were prepared, which mimic coordination motifs of the molybdenum cofactors of molybdenum-dependent oxidoreductases. The model compounds were investigated by Mo K-edge X-ray absorption spectroscopy (XAS) and (with one exception) their molecular structures were analyzed by X-ray diffraction to derive detailed information on bond lengths and geometries of the first coordination shell of molybdenum. Only small variations in Mo=O and Mo-S bond lengths and their respective coordination angles were observed for all complexes including those containing Mo(CO)(2) or Mo(mu-S)(2)Mo motifs. XAS analysis (edge energy) revealed higher relative oxidation levels in the molybdenum ion in compounds with innocent sulfur-based ligands relative to those in dithiolene complexes, which are known to exhibit noninnocence, that is, donation of substantial electron density from ligand to metal. In addition, longer average Mo-S and Mo=O bonds and consequently lower.(Mo=O) stretching frequencies in the IR spectra were observed for complexes with dithiolene-derived ligands. The results emphasize that the noninnocent character of the dithiolene ligand influences the electronic structure of the model compounds, but does not significantly affect their metal coordination geometry, which is largely determined by the Mo(IV) or (V) ion itself. The latter conclusion also holds for the molybdenum site geometries in the oxidized Mo-VI cofactor of DMSO reductase and the reduced Mo-IV cofactor of arsenite oxidase. The innocent behavior of the dithiolene molybdopterin ligands observed in the enzymes is likely to be related to cofactor-protein interactions. KW - Molybdenum KW - Enzyme models KW - X-ray absorption spectroscopy KW - Noninnocence KW - Bioinorganic chemistry Y1 - 2011 U6 - https://doi.org/10.1002/ejic.201100331 SN - 1434-1948 IS - 28 SP - 4387 EP - 4399 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Landau, Alejandra Mabel A1 - Lokstein, Heiko A1 - Scheller, Henrik Vibe A1 - Lainez, Veronica A1 - Maldonado, Sara A1 - Prina, Alberto Raúl T1 - A cytoplasmically inherited barley mutant is defective in photosystem I assembly due to a temperature-sensitive defect in ycf3 splicing N2 - A cytoplasmically inherited chlorophyll-deficient mutant of barley (Hordeum vulgare) termed cytoplasmic line 3 (CL3), displaying a viridis (homogeneously light-green colored) phenotype, has been previously shown to be affected by elevated temperatures. In this article, biochemical, biophysical, and molecular approaches were used to study the CL3 mutant under different temperature and light conditions. The results lead to the conclusion that an impaired assembly of photosystem I (PSI) under higher temperatures and certain light conditions is the primary cause of the CL3 phenotype. Compromised splicing of ycf3 transcripts, particularly at elevated temperature, resulting from a mutation in a noncoding region (intron 1) in the mutant ycf3 gene results in a defective synthesis of Ycf3, which is a chaperone involved in PSI assembly. The defective PSI assembly causes severe photoinhibition and degradation of PSII. Y1 - 2009 UR - http://www.plantphysiol.org/ U6 - https://doi.org/10.1104/pp.109.147843 SN - 0032-0889 ER - TY - JOUR A1 - Chen, Ziping A1 - Warsinke, Axel A1 - Gajovic, Nenad A1 - Große, St. A1 - Hu, J. A1 - Kleber, H.-P. A1 - Scheller, Frieder W. T1 - A D-carnitine dehydrogenase electrode for the assessment of enantiomeric purity of L-carnitine preparations Y1 - 2000 ER - TY - JOUR A1 - Hentrich, Doreen A1 - Taabache, Soraya A1 - Brezesinski, Gerald A1 - Lange, Nele A1 - Unger, Wolfgang A1 - Kuebel, Christian A1 - Bertin, Annabelle A1 - Taubert, Andreas T1 - A Dendritic Amphiphile for Efficient Control of Biomimetic Calcium Phosphate Mineralization JF - Macromolecular bioscience N2 - The phase behavior of a dendritic amphiphile containing a Newkome-type dendron as the hydrophilic moiety and a cholesterol unit as the hydrophobic segment is investigated at the air-liquid interface. The amphiphile forms stable monomolecular films at the airliquid interface on different subphases. Furthermore, the mineralization of calcium phosphate beneath the monolayer at different calcium and phosphate concentrations versus mineralization time shows that at low calcium and phosphate concentrations needles form, whereas flakes and spheres dominate at higher concentrations. Energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and electron diffraction confirm the formation of calcium phosphate. High-resolution transmission electron microscopy and electron diffraction confirm the predominant formation of octacalcium phosphate and hydroxyapatite. The data also indicate that the final products form via a complex multistep reaction, including an association step, where nano-needles aggregate into larger flake-like objects. Y1 - 2017 U6 - https://doi.org/10.1002/mabi.201600524 SN - 1616-5187 SN - 1616-5195 VL - 17 SP - 2541 EP - 2548 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Hlinak, Andreas A1 - Müller, Thomas A1 - Kramer, Matthias A1 - Mühle, Ralf-Udo A1 - Liebherr, Helga A1 - Ziedler, Klaus T1 - A descriptive analysis of the potenrial association between migration patterns of bean and white-fronted geese and the occurence of newcastle disease outbreaks in domestic birds N2 - Sightings and migration patterns of 65 bean and 65 white-fronted geese are reported. These geese were tagged and serologically screened. 19 of the 53 birds sighted had serologic evidence of Newcastle Disease. The migration patterns of the wild geese provided further evidence that the main resting and wintering sites of migratory waterfowl are likely to be important for the inter- and intraspecies transmission of avian diseases. Y1 - 1999 SN - 0005-2086 ER - TY - JOUR A1 - Bukovinszky, Tibor A1 - Helmsing, Nico R. A1 - Grau, R. A. A1 - Bakker, Elisabeth S. A1 - Bezemer, T. Martijn A1 - Vos, Matthijs A1 - Uittenhout, H. A1 - Verschoor, A. M. T1 - A device to study the behavioral responses of zooplankton to food quality and quantity JF - Journal of insect behavior N2 - In order to explore the behavioral mechanisms underlying aggregation of foragers on local resource patches, it is necessary to manipulate the location, quality and quantity of food patches. This requires careful control over the conditions in the foraging arena, which may be a challenging task in the case of aquatic resource-consumer systems, like that of freshwater zooplankton feeding on suspended algal cells. We present an experimental tool designed to aid behavioral ecologists in exploring the consequences of resource characteristics for zooplankton aggregation behavior and movement decisions under conditions where the boundaries and characteristics (quantity and quality) of food patches can be standardized. The aggregation behavior of Daphnia magna and D. galeata x hyalina was tested in relation to i) the presence or absence of food or ii) food quality, where algae of high or low nutrient (phosphorus) content were offered in distinct patches. Individuals of both Daphnia species chose tubes containing food patches and D. galeata x hyalina also showed a preference towards food patches of high nutrient content. We discuss how the described equipment complements other behavioral approaches providing a useful tool to understand animal foraging decisions in environments with heterogeneous resource distributions. KW - Foraging behavior KW - behavioral choice KW - food preference KW - Daphnia KW - flow-through vessel Y1 - 2013 U6 - https://doi.org/10.1007/s10905-012-9366-0 SN - 0892-7553 VL - 26 IS - 4 SP - 453 EP - 465 PB - Springer CY - New York ER -