The “Neuro-Glial-Vascular” Unit: The Role of Glia in Neurovascular Unit Formation and Dysfunction

The neurovascular unit (NVU) is a complex multi-cellular structure consisting of endothelial cells (ECs), neurons, glia, smooth muscle cells (SMCs), and pericytes. Each component is closely linked to each other, establishing a structural and functional unit, regulating central nervous system (CNS) blood flow and energy metabolism as well as forming the blood-brain barrier (BBB) and inner blood-retina barrier (BRB). As the name suggests, the “neuro” and “vascular” components of the NVU are well recognized and neurovascular coupling is the key function of the NVU. However, the NVU consists of multiple cell types and its functionality goes beyond the resulting neurovascular coupling, with cross-component links of signaling, metabolism, and homeostasis. Within the NVU, glia cells have gained increased attention and it is increasingly clear that they fulfill various multi-level functions in the NVU. Glial dysfunctions were shown to precede neuronal and vascular pathologies suggesting central roles for glia in NVU functionality and pathogenesis of disease. In this review, we take a “glio-centric” view on NVU development and function in the retina and brain, how these change in disease, and how advancing experimental techniques will help us address unanswered questions.

THE PECULIARITIES OF FUNCTIONING OF LEXICAL-SEMANTIC VARIANTS OF THE NOUN FIRE IN THE PROCESS OF PHRASEOLOGICAL UNIT FORMATION

The article focuses on the issue of participation of lexical-semantic variants of the polysemous noun Eng. fire in the process of formation of phraseological units. The goal of our article is to find out how the semantic range of the polysemous noun Eng. fire is reproduced in the structure of idioms. To achieve this goal, the author uses the following research methods: descriptive, comparative, the method of dictionary definitions, the method of phraseological application to establish phraseological meanings, as well as the method of establishing the content of language stereotypes. Occasionally, the historical and etymological methods were used, as well as methods of frame modeling and quantitative estimation. The author describes the peculiarities of actualization of the system of lexical meanings of the polysemantic noun Eng. fire at the phraseological level and establishes structural types of phraseological units which are formed with the help of semantemes of the noun Eng. fire. The object of our research is English phraseological units sharing the common key lexical component � polysemanti� noun of thermal semantics Eng. fire. We conduct the research using not only nominative and predicative idiomatic phraseological units, but also comparative phrases, proverbs and speech formulae. In modern phraseology the problem of interrelationships between the lexico-semantic and lexico- -phraseological levels of the language system is currently important. The specificity of functioning of polysemous adjective with thermal meaning Eng. fire in phraseological units is analysed within the framework of research of the general problem of interrelationships between the lexico-semantic and lexico-phraseological levels of the language system. The author finds general trends of sense development of this noun within the structure of idiomatic set phrases sharing the common key lexical component Eng. fire. The analysis shows that lexical meanings of the polysemantic of noun Eng. fire at the phraseological level are actualized unevenly and selectively. In the structure of nominative and predicative idiomatic phraseological units and comparative phrases the key noun Eng. fire implements almost exclusively its original �thermal� semanteme as a formative one, but its lexical semantemes used in the formation of idioms rarely coincide with its phraseo-derived meanings. Individual semantemes of the noun Eng. fire differ with respect to the number of phrasemes they occur in, besides there are many phraseo-derived meanings that don�t have the corresponding lexico-semantic variants of the noun Eng. fire, though some of them have synonymic lexical meanings. To continue the research of semantic relations between lexical and phraseological levels of the language we should involve to our analysis other parts of speech. This aspect, together with the use of information from other languages is necessary for our better understanding of the role of high temperature characteristics, objects and processes in linguistic world image.

Rare Taxa Exhibit Disproportionate Cell-Level Metabolic Activity in Enriched Anaerobic Digestion Microbial Communities

ABSTRACTMicrobial communities are composed of populations with vastly different abundances and levels of metabolic and replicative activity, ranging from actively metabolizing and dividing to dormant or nonviable. The 16S rRNA/rDNA ratio is an emerging tool for evaluating cell-level metabolic activity independent of abundance. In this study, we used five long-term enriched model anaerobic digestion (AD) communities to investigate community composition, diversity, structure, and in particular activity based on the rRNA/rDNA ratio. We cross-validated the 16S amplicon-based results using two alternative operational taxonomic unit (OTU) formation methods (conventional 97% sequence similarity and 100% sequence similar zero-radius OTUs by UNOISE3) and compared these to metagenome-derived population genomes and metatranscriptomes. Significant positive correlations were observed between microbial total activity and abundance with both the amplicon- and omic-based methods. All three methods revealed disproportionately high transcription/abundance ratios for some rare taxa but lower ratios for most abundant taxa for all the communities, which was further corroborated by the high replication rate (iRep) of most low-abundance population genomes.IMPORTANCEVariation in microbial activity levels is increasingly being recognized as both an important dimension in community function and a complicating factor in sequencing-based survey methods. This study extends previous reports that rare taxa may contribute disproportionately to community activity in some natural environments, showing that this may also hold in artificially maintained model communities with well-described inputs, outputs, and biochemical functions. These results demonstrate that assessment of activity levels using the rRNA/rDNA ratio is robust across taxonomic unit formation methods and is independently corroborated by omics methods. The results also provide insight into the comparative advantages and disadvantages of different taxonomic unit formation methods in amplicon sequencing studies, showing that UNOISE3 provides comparable microbial diversity, structure, and activity information as the 97% sequence similarity method but potentially loses some phylogenetic diversity and creates more “phantom taxa” (which are present in the RNA pool but not the corresponding DNA pool).

Hair follicle epidermal stem cells define a niche for tactile sensation

The heterogeneity and compartmentalization of stem cells is a common principle in many epithelia, and is known to function in epithelial maintenance, but its other physiological roles remain elusive. Here we show transcriptional and anatomical contributions of compartmentalized epidermal stem cells in tactile sensory unit formation in the mouse hair follicle. Epidermal stem cells in the follicle upper-bulge, where mechanosensory lanceolate complexes innervate, express a unique set of extracellular matrix (ECM) and neurogenesis-related genes. These epidermal stem cells deposit an ECM protein called EGFL6 into the collar matrix, a novel ECM that tightly ensheathes lanceolate complexes. EGFL6 is required for the proper patterning, touch responses, and αv integrin-enrichment of lanceolate complexes. By maintaining a quiescent original epidermal stem cell niche, the old bulge, epidermal stem cells provide anatomically stable follicle–lanceolate complex interfaces, irrespective of the stage of follicle regeneration cycle. Thus, compartmentalized epidermal stem cells provide a niche linking the hair follicle and the nervous system throughout the hair cycle.