Analyses of the TCR repertoire of MHC class II-restricted innate CD4+ T cells

Analysis of the T-cell receptor (TCR) repertoire of innate CD4⁺ T cells selected by major histocompatibility complex (MHC) class II-dependent thymocyte–thymocyte (T-T) interaction (T-T CD4⁺ T cells) is essential for predicting the characteristics of the antigens that bind to these T cells and for distinguishing T-T CD4⁺ T cells from other types of innate T cells. Using the TCR^mini Tg mouse model, we show that the repertoire of TCRα chains in T-T CD4⁺ T cells was extremely diverse, in contrast to the repertoires previously described for other types of innate T cells. The TCRα chain sequences significantly overlapped between T-T CD4⁺ T cells and conventional CD4⁺ T cells in the thymus and spleen. However, the diversity of the TCRα repertoire of T-T CD4⁺ T cells seemed to be restricted compared with that of conventional CD4⁺ T cells. Interestingly, the frequency of the parental OT-II TCRα chains was significantly reduced in the process of T-T interaction. This diverse and shifted repertoire in T-T CD4⁺ T cells has biological relevance in terms of defense against diverse pathogens and a possible regulatory role during peripheral T-T interaction.     

Fetal hematopoietic stem cells express MFG-E8 during mouse embryogenesis

The milk fat globule-EGF-factor 8 protein (MFG-E8) has been identified in various tissues, where it has an important role in intercellular interactions, cellular migration, and neovascularization. Previous studies showed that MFG-E8 is expressed in different cell types under normal and pathophysiological conditions, but its expression in hematopoietic stem cells (HSCs) during hematopoiesis has not been reported. In the present study, we investigated MFG-E8 expression in multiple hematopoietic tissues at different stages of mouse embryogenesis. Using immunohistochemistry, we showed that MFG-E8 was specifically expressed in CD34⁺ HSCs at all hematopoietic sites, including the yolk sac, aorta-gonad-mesonephros region, placenta and fetal liver, during embryogenesis. Fluorescence-activated cell sorting and polymerase chain reaction analyses demonstrated that CD34⁺ cells, purified from the fetal liver, expressed additional HSC markers, c-Kit and Sca-1, and that these CD34⁺ cells, but not CD34⁻ cells, highly expressed MFG-E8. We also found that MFG-E8 was not expressed in HSCs in adult mouse bone marrow, and that its expression was confined to F4/80⁺ macrophages. Together, this study demonstrates, for the first time, that MFG-8 is expressed in fetal HSC populations, and that MFG-E8 may have a role in embryonic hematopoiesis.     

Metals in surface water of Ukraine: the migration forms,features of distribution between the abiotic components of aquatic ecosystems,and potential bioavailability

We have generalized the results of long-term studies of coexisting forms of a series of metals (Al, Fe, Mn, Zn, Cu, Cr, Pb, Mo, Cd, and V) in surface water bodies of Ukraine, differing in the hydrological regime and the water chemical composition (rivers, reservoirs, lakes, and ponds). The studied metals content has ranged widely, the concentrations of aluminum, iron, and manganese being typically the highest, and the concentration of molybdenum, vanadium, and cadmium being typically the lowest. The ratio between the suspended and the dissolved forms of the metals has been established. Iron and aluminum migrate mostly as part of the suspended matter, whereas the other metals mainly migrate in the dissolved state. The dissolved manganese form predominates in the water bodies under anaerobic conditions. Copper and molybdenum are present almost always in the dissolved state, regardless of the water body type. The data on the relative content of the labile metal fraction (potentially toxic to aquatic organisms) are reported. The relatively low content of this fraction has been found to be majorly owing to the metal ions complexing with natural organic ligands. The humic compounds, the most widespread group of natural organic compounds, play the primary role in the complexation. Even metals with variable oxidation state (Cr, Mo, and V) are found mainly in the form of anionic complexes with the humic substances. Carbohydrates are also involved in the metals binding in the highly bioproductive water bodies, thus increasing the mass fraction of the neutral complexes during the summer and autumn periods. The molecular weight distribution of anionic metal complexes has been discussed; the substantial part of the metals constitutes the compounds with the molecular weight of below 5.0 kDa.     

Calculation of possible stabilization of glycosyl carbocations in furanosides by different theoretical methods

The paper deals with the comparison of different theoretical methods for the calculation of stabilization energies of glycosyl cations from fucofuranoside glycosyl donors containing different protecting groups at atom O(3). The experimental and calculated data on stereoselectivity of glycosylation were compared. The formation of the stabilized glycosyl cations is considered as one of the possible steps of glycosylation reaction, which exerts influence on the stereoselectivity of the process and makes it possible to obtain difficultly accessible 1,2-cis-glycosides. Semi-empirical and ab initio methods without allowance for the electron correlation underestimate the stabilization energy values. The allowance for the electron correlation in the MP2 approximation, as well as the calculations by density functional theory, allowed us to obtain the data corresponding to the experimentally observed stereoselectivity.     

Chalcogenation of 1,4-dichlorobut-2-yne with organic dichalcogenides in the system hydrazine hydrate–KOH

A reaction of organic dichalcogenides R₂Y₂ (R = Ph, Bn, Pr; Y = S, Se) with 1,4-dichlorobut-2-yne in the system hydrazine hydrate–KOH leads to four principal products: 1,4-bis(organylchalcogenyl)but-2-ynes, 1-organylchalcogenylbut-1-en-3-ynes, 4-organylchalcogenylbut-1-en-3-ynes, and 3(5)-methylpyrazole. The selectivity of the formation of individual products is determined by the ratio of the substrates used and the reaction temperature. A plausible mechanism of chalcogenation considered in the work agrees with the effect of the nature of chalcogene atoms and organic substituents R on stability of intermediates and products. The stabilization of carbanions by α chalcogene-containing groups corresponds to the following order: PhS > PhSe > BnS > BnSe > PrS.     

Interaction of amorphous and crystalline nickel nanoparticles with hydrogen

Nickel nanoparticles were deposited on the surface of highly oriented pyrolytical graphite by laser electrodispersion and precipitation from a solution of reverse micelles. The particles were studied using scanning tunneling microscopy and spectroscopy as well as Auger spectroscopy. The elemental composition of the nanoparticles and specific features of the electronic structure of their surface were determined. Adsorption of molecular hydrogen was also studied.     

Integrated One‐Flow Synthesis of Heterocyclic Thioquinazolinones through Serial Microreactions with Two Organolithium Intermediates

The synthesis of pharmaceutical compounds via short‐lived intermediates in a microreactor is attractive, because of the fast flow and high throughput. Additionally, intermediates can be utilized sequentially to efficiently build up a library in a short time. Here we present an integrated microfluidic synthesis of biologically active thioquinazolinone libraries. Generation of o‐lithiophenyl isothiocyanate and subsequent reaction with aryl isocyanate is optimized by controlling the residence time in the microreactor to 16 ms at room temperature. Various S‐benzylic thioquinazolinone derivatives are synthesized within 10 s in high yields (75–98 %) at room temperature. These three‐step reactions involve two organolithium intermediates, an isothiocyanate‐functionalized aryllithium intermediate, and a subsequent lithium thiolate intermediate. We also demonstrate the gram‐scale synthesis of a multifunctionalized thioquinazolinone in the microfluidic device with a high yield (91 %) and productivity (1.25 g in 5 min).