Modeling of the composition of materials for soft X-ray sources used in research on inertial confinement fusion

A method for calculating and optimizing the composition of materials for soft X-ray sources used in research on inertial confinement fusion is described. For a target-converter, a material composition is determined with which the conversion of laser light into X radiation is highly efficient. A comparative analysis is carried out of the efficiencies of generation of soft X-ray emission in the plasmas of some composite materials of thin conductors (wires) used as loads in X-and Z-pinches. Numerical calculations of the optical plasma properties are reported whose results make it possible to judge the emissivity of plasmas of different materials. The results obtained are compared to the data from other studies.     

Karyology and Cytotaxonomy of the Genus Chrysolina Motschulsky (Coleoptera, Chrysomelidae)

Eight species of Chrysolina have been chromosomally studied in male individuals from Central Europe, South France and the Urals, in Russia. Ch. rufa had 2n = 23, Ch. purpurascens crassimargo 2n = 24 and a meioformula of 11 + Xy_p, Ch. globosa and Ch. bigorrensis 12 + Xy_p, Ch. umbratilis 2n = 30 and 14 + XY_p, a new non-chiasmate sex-chromosome system with both male sex-chromosomes of large size, Ch. cf. subcostata 12 + XY_p with large sex-chromosomes also, Ch. interstincta 2n = 40 and 19 + Xy_p, and Ch. obscurella 2n = 47. The taxonomic implications of these findings are discussed in relation with the current subgeneric classification of Chrysolina and principally that of the subgenera Colaphoptera, Sphaerochrysolina, Pleurosticha, Chalcoidea and Threnosoma.     

Influence of Electroporation Conditions on Transfection of Muscle Fibers in Vivo

This study is a survey of in vivo experiments on transfection of laboratory mouse muscle fibers by electoporation using an original device generating electric impulses. Transfection efficiency proved to depend on DNA dose and the number of electric impulses. It can be increased significantly by electroporation at varying pulse burst polarity. At both direct electrode application to muscles and electroporation through the skin, the muscle fiber transfection was more efficient under electroporation conditions much milder than those usually reported. The use of electroporation method for gene therapy of Duchenne muscular dystrophy is discussed.     

Molecular structure of the glibenclamide binding site of the beta-cell K(ATP) channel.

We have investigated the structure of the glibenclamide binding site of pancreatic beta-cell ATP-sensitive potassium (K(ATP)) channels. K(ATP) channels are a complex of four pore-forming Kir6.2 subunits and four sulfonylurea receptor (SUR1) subunits. SUR1 (ABCC8) belongs to the ATP binding cassette family of proteins and has two nucleotide binding domains (NBD1 and NBD2) and 17 putative transmembrane (TM) sequences. Co-expression in a baculovirus expression system of two parts of SUR1 between NBD1 and TM12 leads to restoration of glibenclamide binding activity, whereas expression of either individual N- or C-terminal part alone gave no glibenclamide binding activity, confirming a bivalent structure of the glibenclamide binding site. By using N-terminally truncated recombinant proteins we have shown that CL3 - the cytosolic loop between TM5 and TM6 - plays a key role in formation of the N-terminal component of the glibenclamide binding site. Analysis of deletion variants of the C-terminal part of SUR1 showed that CL8 - the cytosolic loop between TM15 and TM16 - is the only determinant for the C-terminal component of the glibenclamide binding site. We suggest that in SUR1 in the native K(ATP) channel close proximity of CL3 and CL8 leads to formation of the glibenclamide binding site.     

A Comparative Study on the Cleavage of Stereoisomeric Uridylyl (3',5')Uridines [D,D-, D,L- and L,D-UPU] by Acid,Base and Metal Ion Catalysts

Stereoisomeric uridylyl(3',5')uridines D,L-UpU andL,D-UpU were synthesised. Their cleavage was followed in thepresence of acid, base and metal ion catalysts to studywhether the stereochemistry affects the inherent reactivity ofthe internucleosidic phosphodiester bond, and whether the lowmolecular weight catalysts can distinguish between thesubstrates. The rate constants obtained were compared to thoseof D,D-UpU. The comparison shows that the stability of thephosphodiester bond does not depend on the stereochemistry ofthe sugar rings. In contrast slight reactivity differences areobserved in the presence of metal ion catalysts, whichsuggests that selective cleavage of stereoisomeric substrateseven by small molecular weight chemical catalysts may bepossible.     

Gangliosides of sea urchin embryos. Their localization and participation in early development

The influence of antibodies to gangliosides of sea urchin Strongylocentrotus intermedius eggs on early embryos of this species was studied. gamma-Globulins were isolated from rabbit anti-ganglioside serum by micropreparative electrophoresis. These gamma-globulins produced anomalies in the development of embryos permeabilized in Triton X-100. The anomalies were not observed when anti-ganglioside gamma-globulins were added to the incubation medium together with gangliosides or when the permeabilized embryos were incubated with gamma-globulins of normal rabbit serum. Pretreatment of S. intermedius embryos with serotonin, tryptamine or some other indole derivatives led to the disappearance of ganglioside determinants from the cell surface and sharply increased immunofluorescence within the cell. Such pretreatment of embryos increased the amount of cell-associated gangliosides more than threefold as compared to untreated embryos. Serotonin was shown to bind specifically to sea urchin gangliosides immobilized on octyl-Sepharose. These observations suggest that cell-surface gangliosides, after binding drugs, are internalized and that serotonin and its antagonists inhibit the transport of newly synthesized gangliosides to the cell-surface membrane.     

Studies on Disaccharide Nucleoside Synthesis. Mechanism of the Formation of Trisaccharide Purine Nucleosides

Abstract

The unexpected formation of trisaccharide nucleosides during synthesis of purine 5′-O-β-D-ribofuranosylnucleosides in the presence of Lewis acids was observed.