114 research outputs found

    Vom "Greis" zum "Silver Ager"? : Sprachkritische Anmerkungen zu ab- und aufwertenden Bezeichnungen für ältere Menschen

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    Es hat Zeiten gegeben, in denen sich Autoren der verschiedensten Disziplinen auf »die Alten« beriefen, wenn sie ihre Argumentation mit Verweis auf Autoritäten der Vergangenheit, meist der Antike, absichern wollten. Das waren Zeiten, in denen »die Alten« insgesamt ein hohes Ansehen hatten. Auch die traditionelle Darstellung des christlichen Gottvaters als alter Mann sollte ihn eindeutig als Respektsperson auszeichnen. Im ältesten deutschen Heldenlied, dem »Hildebrandslied« (Aufzeichnung im 9. Jahrhundert), ist es entsprechend der Vater Hildebrand, der aufgrund seines Alters vor seinem Sohn das Wort ergreifen darf. ..

    2-[(1-Methyl-1H-pyrrol-2-yl)carbonyl­meth­yl]isoindoline-1,3-dione

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    The asymmetric unit of the title compound, C15H12N2O3, contains two almost identical mol­ecules forming an nearly C 2-symmetric dimeric pattern. The dihedral angles between the pyrrole ring and the phthalimide unit are 82.95 (8) and 86.57 (8)° for the two mol­ecules. Within such a dimer, the phthalimide units of the two mol­ecules form a dihedral angle of 1.5 (5)°

    Cornforth–Evans Transition States in Stereocontrolled Allylborations of Epoxy Aldehydes

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    Allylboration reactions rank among the most reliable tools in organic synthesis. Herein, we report a general synthesis of trifunctionalized allylboronates and systematic investigations of their stereocontrolled transformations with substituted aldehyde substrates, in order to efficiently access diverse, highly substituted target substrates. A peculiar transition in stereocontrol was observed from the polar Felkin–Anh (PFA) to the Cornforth–Evans (CE) model for alkoxy‐ and epoxy‐substituted aldehydes. CE‐type transition states were uniformly identified as minima in advanced, DFT‐based computational studies of allylboration reactions of epoxy aldehydes, conforming well to the experimental data, and highlighting the underestimated relevance of this model. Furthermore, a mechanism‐based rationale for the substitution pattern of the epoxide was delineated that ensures high levels of stereocontrol and renders α,β‐epoxy aldehydes generally applicable substrates for target synthesis

    Demography and Population Projections of the Invasive Tunicate Styela clava in southern New Zealand

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    This thesis is about the demography of the tunicate Styela clava, a species of some notoriety because of its invasiveness and impacts in many parts of the world. Species assemblages have continuously changed throughout evolutionary history, but the rate of today’s anthropogenically facilitated dispersal is unparalleled in history. Non-indigenous species (NIS) are now considered one of the most important risks to native biodiversity. NIS become invasive by becoming both widespread and locally dominant. This requires that a species becomes established, spreads locally, and increases in abundance. In the early stages of invasion, its demography and life history characteristics are of crucial importance. In New Zealand, Styela has established populations in several places, but none of these populations has yet reached the high densities found in other countries. In Lyttelton Port, where this study was located, Styela was first noticed in 2005. It therefore presented an ideal situation to study an invasive species in its early stages of establishment and provided a potentially good model for understanding how invasive species get local traction and spread from initial infestation points. Therefore, I set out to determine demographic features of Styela to understand the numbers game of population dynamics. This study used empirical data on growth rates, size-frequencies through time, and size and age to maturity to test several models, including von Bertalanffy, Logistic dose-response, Ricker and power models of individual growth. The most useful proved to be the von Bertalanffy model. Styela individuals shrink frequently, so average growth rates were often quite low, even though some individuals reached 160 mm or more in total length. Mortality was greatest in summer, presumably after reproduction, and lowest in winter. Fewer than 5% of individuals survived 12 months, and most or all of these died soon afterwards. Populations were, therefore, essentially annual. Recruitment was difficult to determine because of the cryptic nature of small juveniles. However, size-frequency, abundance and mortality data indicated that recruitment most likely occurred in early spring (late-October), and then again in late summer, with growth to maturity (at c. 50 mm total length) within < 5 months. Several manipulative experiments showed that Styela did not readily capitalise on provision of free space but the other non-native ascidian, Ciona intestinalis, rapidly recruited. Transplants of Styela were greatly affected by C. intestinalis, which overgrew them, similar to a localised replacement of Styela by Ciona seen overseas. Lefkovitch modelling was used to test whether Styela had an “Achilles heel” in its life history, whereby managed removal could impact future populations. This showed that under several scenarios intervention would most likely be ineffectual. Overall, this study showed that the original populations in Lyttelton Port are either static or in decline, somewhat contrary to original expectations. Nevertheless, it appears that these small populations may be acting as stepping stones for spread of this species outside of the port

    7-[4-(4-Fluoro­phen­yl)-2-methyl­sulfanyl-1H-imidazol-5-yl]tetra­zolo[1,5-a]pyridine

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    The crystal structure of the title compound, C15H11FN6S, forms a three-dimensional network stabilized by π–π inter­actions between the imidazole core and the tetra­zole ring of the tetra­zolopyridine­unit; the centroid–centroid distance is 3.627 (1) Å. The crystal structure also displays bifurcated N—H⋯(N,N) hydrogen bonding and C—H⋯F inter­actions. The former involve the NH H atom of the imidazole core and the tetra­zolopyridine N atoms, while the latter involve a methyl H atom, of the methyl­sulfanyl group, and the 4-fluoro­phenyl F atom. In the mol­ecule, the imidazole ring makes dihedral angles of 40.45 (9) and 17.09 (8)°, respectively, with the 4-fluoro­phenyl ring and the tetra­zolopyridine ring mean plane

    Non-canonical shedding of TNFα by SPPL2a is determined by the conformational flexibility of its transmembrane helix

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    Ectodomain (EC) shedding defines the proteolytic removal of a membrane protein EC and acts as an important molecular switch in signaling and other cellular processes. Using tumor necrosis factor (TNF)α as a model substrate, we identify a non-canonical shedding activity of SPPL2a, an intramembrane cleaving aspartyl protease of the GxGD type. Proline insertions in the TNFα transmembrane (TM) helix strongly increased SPPL2a non-canonical shedding, while leucine mutations decreased this cleavage. Using biophysical and structural analysis, as well as molecular dynamic simulations, we identified a flexible region in the center of the TNFα wildtype TM domain, which plays an important role in the processing of TNFα by SPPL2a. This study combines molecular biology, biochemistry, and biophysics to provide insights into the dynamic architecture of a substrate\u27s TM helix and its impact on non-canonical shedding. Thus, these data will provide the basis to identify further physiological substrates of non-canonical shedding in the future

    Non-canonical Shedding of TNFα by SPPL2a Is Determined by the Conformational Flexibility of Its Transmembrane Helix

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    Ectodomain (EC) shedding defines the proteolytic removal of a membrane protein EC and acts as an important molecular switch in signaling and other cellular processes. Using tumor necrosis factor (TNF)α as a model substrate, we identify a non-canonical shedding activity of SPPL2a, an intramembrane cleaving aspartyl protease of the GxGD type. Proline insertions in the TNFα transmembrane (TM) helix strongly increased SPPL2a non-canonical shedding, while leucine mutations decreased this cleavage. Using biophysical and structural analysis, as well as molecular dynamic simulations, we identified a flexible region in the center of the TNFα wildtype TM domain, which plays an important role in the processing of TNFα by SPPL2a. This study combines molecular biology, biochemistry, and biophysics to provide insights into the dynamic architecture of a substrate\u27s TM helix and its impact on non-canonical shedding. Thus, these data will provide the basis to identify further physiological substrates of non-canonical shedding in the future

    Helical stability of the GnTV transmembrane domain impacts on SPPL3 dependent cleavage

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    Signal-Peptide Peptidase Like-3 (SPPL3) is an intramembrane cleaving aspartyl protease that causes secretion of extracellular domains from type-II transmembrane proteins. Numerous Golgi-localized glycosidases and glucosyltransferases have been identified as physiological SPPL3 substrates. By SPPL3 dependent processing, glycan-transferring enzymes are deactivated inside the cell, as their active site-containing domain is cleaved and secreted. Thus, SPPL3 impacts on glycan patterns of many cellular and secreted proteins and can regulate protein glycosylation. However, the characteristics that make a substrate a favourable candidate for SPPL3-dependent cleavage remain unknown. To gain insights into substrate requirements, we investigated the function of a GxxxG motif located in the transmembrane domain of N-acetylglucosaminyltransferase V (GnTV), a well-known SPPL3 substrate. SPPL3-dependent secretion of the substrate’s ectodomain was affected by mutations disrupting the GxxxG motif. Using deuterium/hydrogen exchange and NMR spectroscopy, we studied the effect of these mutations on the helix flexibility of the GnTV transmembrane domain and observed that increased flexibility facilitates SPPL3-dependent shedding and vice versa. This study provides first insights into the characteristics of SPPL3 substrates, combining molecular biology, biochemistry, and biophysical techniques and its results will provide the basis for better understanding the characteristics of SPPL3 substrates with implications for the substrates of other intramembrane proteases
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