196 research outputs found

    ‘Negatives Face’, ‘positives Face’ etc. Was Gesprachsanalytiker von Erving Goffman Iernen konnen

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    В статье рассматриваются актуальные вопросы анализа персонифицированной речевой коммуникации (диалога) с точки зрения оригинальной концепции Э. Гофмана (США)

    Verbale Aggressionen und Streitgesprache - und was die Linguistik dazu zu sagen hat

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    В статье рассматриваются в исторической перспективе речевые стратегии и формы в жанре спора

    The Korringa-Kohn-Rostoker Non-Local Coherent Potential Approximation (KKR-NLCPA)

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    We introduce the Korringa-Kohn-Rostocker non-local coherent potential approximation (KKR-NLCPA) for describing the electronic structure of disordered systems. The KKR-NLCPA systematically provides a hierarchy of improvements upon the widely used KKR-CPA approach and includes non-local correlations in the disorder configurations by means of a self-consistently embedded cluster. The KKR-NLCPA method satisfies all of the requirements for a successful cluster generalization of the KKR-CPA; it remains fully causal, becomes exact in the limit of large cluster sizes, reduces to the KKR-CPA for a single-site cluster, is straightforward to implement numerically, and enables the effects of short-range order upon the electronic structure to be investigated. In particular, it is suitable for combination with electronic density functional theory to give an ab-initio description of disordered systems. Future applications to charge correlation and lattice displacement effects in alloys and spin fluctuations in magnets amongst others are very promising. We illustrate the method by application to a simple one-dimensional model.Comment: Revised versio

    Comparative genomic and metabolomic analysis of Termitomyces species provides insights into the terpenome of the fungal cultivar and the characteristic odor of the fungus garden of Macrotermes natalensis termites

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    Macrotermitinae termites have domesticated fungi of the genus Termitomyces as food for their colony, analogously to human farmers growing crops. Termites propagate the fungus by continuously blending foraged and predigested plant material with fungal mycelium and spores (fungus comb) within designated subterranean chambers. To test the hypothesis that the obligate fungal symbiont emits specific volatiles (odor) to orchestrate its life cycle and symbiotic relations, we determined the typical volatile emission of fungus comb biomass and Termitomyces nodules, revealing α-pinene, camphene, and d-limonene as the most abundant terpenes. Genome mining of Termitomyces followed by gene expression studies and phylogenetic analysis of putative enzymes related to secondary metabolite production encoded by the genomes uncovered a conserved and specific biosynthetic repertoire across strains. Finally, we proved by heterologous expression and in vitro enzymatic assays that a highly expressed gene sequence encodes a rare bifunctional mono-/sesquiterpene cyclase able to produce the abundant comb volatiles camphene and d-limonene. IMPORTANCE The symbiosis between macrotermitinae termites and Termitomyces is obligate for both partners and is one of the most important contributors to biomass conversion in the Old World tropic’s ecosystems. To date, research efforts have dominantly focused on acquiring a better understanding of the degradative capabilities of Termitomyces to sustain the obligate nutritional symbiosis, but our knowledge of the small-molecule repertoire of the fungal cultivar mediating interspecies and interkingdom interactions has remained fragmented. Our omics-driven chemical, genomic, and phylogenetic study provides new insights into the volatilome and biosynthetic capabilities of the evolutionarily conserved fungal genus Termitomyces, which allows matching metabolites to genes and enzymes and, thus, opens a new source of unique and rare enzymatic transformations

    Nocardia macrotermitis sp. nov. and Nocardia aurantia sp. nov., isolated from the gut of the fungus-growing termite Macrotermes natalensis

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    The taxonomic positions of two novel aerobic, Gram-stain-positive Actinobacteria, designated RB20T^{T} and RB56T^{T}, were determined using a polyphasic approach. Both were isolated from the fungus-farming termite Macrotermes natalensis. Results of 16S rRNA gene sequence analysis revealed that both strains are members of the genus Nocardia with the closest phylogenetic neighbours Nocardia miyunensis JCM12860T^{T} (98.9 %) and Nocardia nova DSM44481T^{T} (98.5 %) for RB20T^{T} and Nocardia takedensis DSM 44801T^{T} (98.3 %), Nocardia pseudobrasiliensis DSM 44290T^{T} (98.3 %) and Nocardia rayongensis JCM 19832T^{T} (98.2 %) for RB56T^{T}. Digital DNA–DNA hybridization (DDH) between RB20T^{T} and N. miyunensis JCM12860T^{T} and N. nova DSM 44481T^{T} resulted in similarity values of 33.9 and 22.0 %, respectively. DDH between RB56T^{T} and N. takedensis DSM44801T^{T} and N. pseudobrasiliensis DSM44290T^{T} showed similarity values of 20.7 and 22.3 %, respectively. In addition, wet-lab DDH between RB56T^{T} and N. rayongensis JCM19832T^{T} resulted in 10.2 % (14.5 %) similarity. Both strains showed morphological and chemotaxonomic features typical for the genus Nocardia , such as the presence of meso-diaminopimelic acid (A2_{2}pm) within the cell wall, arabinose and galactose as major sugar components within whole cell-wall hydrolysates, the presence of mycolic acids and major phospholipids (diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol), and the predominant menaquinone MK-8 (H4, ω-cyclo). The main fatty acids for both strains were hexadecanoic acid (C16:0_{16 : 0}), 10-methyloctadecanoic acid (10-methyl C18:0_{18 : 0}) and cis-9-octadecenoic acid (C18:1_{18 : 1} ω9c). We propose two novel species within the genus Nocardia : Nocardia macrotermitis sp. nov. with the type strain RB20T^{T} (=VKM Ac-2841T^{T}=NRRL B65541T^{T}) and Nocardia aurantia sp. nov. with the type strain RB56T^{T} (=VKM Ac-2842T^{T}=NRRL B65542T^{T})

    Metaplastic Cdx2-depleted cells can be very disruptive neighbors.

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    In this issue of JEM, Balbinot et al. (https://doi.org/10.1084/jem.20170934) describe an original mechanism where Cdx2 inactivation regulates intestinal metaplastic to neoplastic transition in a paracrine fashion. Surprisingly, the target cells are neighboring "normal" Cdx2-positive cells

    TGFβ pathway limits dedifferentiation following WNT and MAPK pathway activation to suppress intestinal tumourigenesis

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    Recent studies have suggested increased plasticity of differentiated cells within the intestine to act both as intestinal stem cells (ISCs) and tumour-initiating cells. However, little is known of the processes that regulate this plasticity. Our previous work has shown that activating mutations of Kras or the NF-κB pathway can drive dedifferentiation of intestinal cells lacking Apc. To investigate this process further, we profiled both cells undergoing dedifferentiation in vitro and tumours generated from these cells in vivo by gene expression analysis. Remarkably, no clear differences were observed in the tumours; however, during dedifferentiation in vitro we found a marked upregulation of TGFβ signalling, a pathway commonly mutated in colorectal cancer (CRC). Genetic inactivation of TGFβ type 1 receptor (Tgfbr1/Alk5) enhanced the ability of KrasG12D/+ mutation to drive dedifferentiation and markedly accelerated tumourigenesis. Mechanistically this is associated with a marked activation of MAPK signalling. Tumourigenesis from differentiated compartments is potently inhibited by MEK inhibition. Taken together, we show that tumours arising in differentiated compartments will be exposed to different suppressive signals, for example, TGFβ and blockade of these makes tumourigenesis more efficient from this compartment

    Aberrant epithelial GREM1 expression initiates colonic tumorigenesis from cells outside the stem cell niche

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    Hereditary mixed polyposis syndrome (HMPS) is characterized by the development of mixed-morphology colorectal tumors and is caused by a 40-kb genetic duplication that results in aberrant epithelial expression of the gene encoding mesenchymal bone morphogenetic protein antagonist, GREM1. Here we use HMPS tissue and a mouse model of the disease to show that epithelial GREM1 disrupts homeostatic intestinal morphogen gradients, altering cell fate that is normally determined by position along the vertical epithelial axis. This promotes the persistence and/or reacquisition of stem cell properties in Lgr5-negative progenitor cells that have exited the stem cell niche. These cells form ectopic crypts, proliferate, accumulate somatic mutations and can initiate intestinal neoplasia, indicating that the crypt base stem cell is not the sole cell of origin of colorectal cancer. Furthermore, we show that epithelial expression of GREM1 also occurs in traditional serrated adenomas, sporadic premalignant lesions with a hitherto unknown pathogenesis, and these lesions can be considered the sporadic equivalents of HMPS polyps

    Tumour Cell Heterogeneity.

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    The population of cells that make up a cancer are manifestly heterogeneous at the genetic, epigenetic, and phenotypic levels. In this mini-review, we summarise the extent of intra-tumour heterogeneity (ITH) across human malignancies, review the mechanisms that are responsible for generating and maintaining ITH, and discuss the ramifications and opportunities that ITH presents for cancer prognostication and treatment
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