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HDV-like self-cleaving ribozymes have been found in a wide variety of organisms, implicated in diverse biological processes, and their activity typically shows a strong divalent metal dependence, but little metal specificity. Recent studies suggested that very short variants of these ribozymes exist in nature, but their distribution and biochemical properties have not been established. To map out the distribution of small HDV-like ribozymes, the drz-Spur-3 sequence was minimized to yield a core construct for structure-based bioinformatic searches. These searches revealed several microbial ribozymes, particularly in the human microbiome. Kinetic profile of the smallest ribozyme revealed two distinct metal binding sites, only one of which promotes fast catalysis. Furthermore, this ribozyme showed markedly reduced activity in Ca(2+), even in the presence of physiological Mg(2+) concentrations. Our study substantially expands the number of microbial HDV-like ribozymes and provides an example of cleavage regulation by divalent metals.

In vitro selection and structure-based searches have emerged as useful techniques for the discoveries of structurally complex RNAs with high affinity and specificity toward metabolites. Here, we focus on the design of a human genomic library that serves as the DNA template for in vitro selection of RNA aptamers. In addition, the structural solutions obtained from the in vitro selection can be used for structure-based searches for discovery of analogous aptamers in various genomic databases.

In vitro selection and structure-based searches have emerged as useful techniques for the discoveries of structurally complex RNAs with high affinity and specificity toward metabolites. Here, we focus on the design of a human genomic library that serves as the DNA template for in vitro selection of RNA aptamers. In addition, the structural solutions obtained from the in vitro selection can be used for structure-based searches for discovery of analogous aptamers in various genomic databases.

In the present article, we reflect on the victimization survey conducted as part of the research project BRIZOLIT (Security Risks in Socially Excluded Localities). Our main focus is on the methodological, epistemological and ethical problems which appeared during the survey among inhabitants of the so-called socially excluded localities in April — August 2016. More specifically, we will deal with the issues related to the construction of our research object, interviewing strategies, as well as problems of validity of survey data with regard to the complex processes of victimization in socially excluded localities. In other words, we will try to answer three rather basic questions: „Who did we research? How did we do it? How did we record our findings?“ and hope to provide clues for future researchers facing similar problems.

This work deals with comparing the mechanical properties of OFHC copper and CuCrZr alloys processed by asymmetric ambient rolling (ASaR) and asymmetric cryorolling (AScR). The conditions for asymmetrical rolling were ensured by different diameters of the main rolls. The thickness of samples was reduced about 20% - 70% at ambient temperature and at a temperature of liquid nitrogen. Mechanical properties such as yield strength, tensile strength, reduction of area and microhardness were determined for all rolled samples. Rolling at cryogenic temperatures provide about 50-60MPa more tensile strength for Cu and 60-80 MPa for CuCrZr alloys when rolling at ambient temperature. After AScR of CuCrZr alloys, a start of precipitation was shifted at the temperature of 434∘C and recrystallization was a part of the precipitation peak. According to the results, plastic deformation through shear bands is the dominant mechanism in materials with lower stacking fault energy (CuCrZr) treated under cryogenic conditions.

Hepatitis delta virus (HDV) and cytoplasmic polyadenylation element-binding protein 3 (CPEB3) ribozymes form a family of self-cleaving RNAs characterized by a conserved nested double-pseudoknot and minimal sequence conservation. Secondary structure-based searches were used to identify sequences capable of forming this fold, and their self-cleavage activity was confirmed in vitro. Active sequences were uncovered in several marine organisms, two nematodes, an arthropod, a bacterium, and an insect virus, often in multiple sequence families and copies. Sequence searches based on identified ribozymes showed that plants, fungi, and a unicellular eukaryote also harbor the ribozymes. In Anopheles gambiae, the ribozymes were found differentially expressed and self-cleaved at basic developmental stages. Our results indicate that HDV-like ribozymes are abundant in nature and suggest that self-cleaving RNAs may play a variety of biological roles.

Although the active site of group I introns is phylogenetically conserved, subclasses of introns have evolved different mechanisms of stabilizing the catalytic core. Large introns contain weakly conserved 'peripheral' domains that buttress the core through predicted interhelical contacts, while smaller introns use loop-helix interactions for stability. In all cases, specific and non-specific magnesium ion binding accompanies folding into the active structure. Whether similar RNA-RNA and RNA-magnesium ion contacts play related functional roles in different introns is not clear, particularly since it can be difficult to distinguish interactions directly involved in catalysis from those important for RNA folding. Using phosphorothioate interference with RNA activity and structure in the small (249 nt) group I intron from Anabaena, we used two independent assays to detect backbone phosphates important for catalysis and those involved in intron folding. Comparison of the interference sites identified in each assay shows that positions affecting catalysis cluster primarily in the conserved core of the intron, consistent with conservation of functionally important phosphates, many of which are magnesium ion binding sites, in diverse group I introns, including those from Azoarcus and Tetrahymena. However, unique sites of folding interference located outside the catalytic core imply that different group I introns, even within the same subclass, use distinct sets of tertiary interactions to stabilize the structure of the catalytic core.

This paper is focused on the permeability of cement composite samples with various admixtures. Permeability was examined by the rapid chloride permeability test due to the simple and relatively quick performance among the many methods. Permeability is one of the durability parameters considering the pore system of the composite structure. Ion diffusion provides information about inner pore structure by passing a charge through the sample. In real-life conditions, not only chlorides but also other ions can penetrate into the structure and cause corrosion. Various cement supplements were used as admixtures. The reference sample consisted of cement, fine sand, and water, while the rest of the samples consisted of 20% blast furnace slag, bypass dust, eggshells or recycled glass instead of the cement. The results showed lower permeability in samples containing blast furnace slag and eggshells and a higher charge passage in samples with recycled glass and bypass dust than for the reference sample. [ABSTRACT FROM AUTHOR]

Studie se věnuje dnes již zaniklé dělnické kolonii Karlov, kterou v Plzni zbudovaly Škodovy závody počátkem druhého desetiletí 20. století. V textu studujeme toto dnes již neexistující místo v kontextu transformujícího se urbánního prostoru průmyslové metropole a jeho vztah k pamětnickým reprezentacím. Na základě dat z rozhovorů s pamětníky, zúčastněného pozorování komemorativních setkání a archivního výzkumu zachycujeme vyjednávané změny v reprezentačních praktikách „Karlováků“. Tak v textu zkoumáme dva Karlovy. Prvním je Karlov vzpomínkový, tak, jak je komemorován a utvářen původními obyvateli Karlova, kteří se jako společenstvo vzpomínání pravidelně scházejí, když retroaktivně konstruují Karlov jako smysluplné a ideální místo pro život v městském prostoru. Dále se věnujeme tomu, jak a proč se tento vzpomínkový Karlov brání tomu být ztotožňován se zbytkovým Karlovem, tj. s fyzickými a architektonickými pozůstatky komemorovaného místa.