[Modified Oligonucleotides for Guiding RNA Cleavage Using Bacterial RNase P].

The ability of a series of novel modified external guide sequences (EGS oligonucleotides) to induce the hydrolysis of target RNA with bacterial ribonuclease P has been studied; the most efficient modification variants have been selected. We have found patterns of the oligonucleotide sugar-phosphate backbone modi-fications that enhance oligonucleotide stability in the biological environment and do not violate the ability to interact with the enzyme and induce the RNA hydrolysis. It has been shown that analogues of EGS oligonucleotides selectively modified at 2'-position (2'-O-methyl and 2'-fluoro) or at internucleotide phosphates (phosphoryl guanidines) can be used for the addressed cleavage of a model RNA target by bacterial RNase P. The ability of new phosphoryl guanidine analogues of oligodeoxyribonucleotides that are stable in biological media to induce the hydrolysis of target RNA with bacterial ribonuclease P has been shown for the first time. The modified EGS oligonucleotides with an optimal balance between functional activity and stability in biological media can be considered as potential antibacterial agents.

Field emission properties of a graphene/polymer composite.

Thin graphene/polymer sheet composites were fabricated using easily soluble expanded graphite (ESEG), and their field emission (FE) parameters were examined. Due to the high dispersability of ESEG, a stable graphene suspension was prepared by ultrasonication in toluene without the need for a surfactant. The suspension consisted of exfoliated graphene sheets with a thickness of 1 - 2 nm. Using a calendering process, the solution was further shear mixed with ethyl cellulose to obtain a well-dispersed graphene/polymer composite. The composite was screen printed onto a conducing substrate to fabricate the FE cathode layers. The FE measurements were taken in a diode configuration at an applied electrostatic field and inter-electrode distance of 1.7 to 6 V/microm and approximately 200 microm, respectively. The threshold turn-on-field was approximately 3.5 V/microm at a current density of approximately 10 microA/cm2 with a corresponding mean field enhancement factor of 1350 +/- 50. Emission occurred mainly from the edges and bends of the graphene layers. The luminescence uniformity of the composite cathode layers was examined using a phosphor-coated anode.

[Ecology of the geohelminths of Karakul sheep in the Kyzyl Kum]. / Izuchenie ékologii geogel'mintov karakul'skikh ovets v usloviiakh Kyzylkumov.

Data on the ecology of geohelminths and epizootiology of main geohelminthiases of Karakul sheep under conditions of desert-pasture biocoenoses of the Kyzyl Kum in the Bukhara and Navoi Provinces of the Uzbek SSR are given. 23 species of geohelminths belonging to 14 genera and 8 families are reported from this zone. Age and seasonal dynamics of the infection rate of Karakul sheep with geohelminths are established. Survival of eggs and larvae of some widely distributed geohelminths in central Kyzyl Kum is determined. On the basis of results of investigations recommendations on the control of main helminthiases of Karakul sheep in Bukhara and Navoi Provinces are worked out.