Binding and transfer of an oligodeoxynucleotide containing the translation initiation site of the <Emphasis Type="Italic">BCL2</Emphasis> mRNA into K562 cells

A study was conducted of the interaction of an octadecameric oligodeoxynucleotide (dON) containing the BCL2 mRNA translation start with K562 cells. Both in solution and upon lipofection, the binding of dON used at a low concentration (30 nM) at 37°C involved two steps: saturating surface binding with the cell membrane and internalization. Three phases were revealed in the dynamics of internalization: the extent and rate of internalization increased during the first hour of incubation; decreased during the second hour; and then increased again, which was assumed to reflect the priming of new dON-binding sites. The binding constant and the number of binding sites were estimated at 10°C (the conditions preventing internalization) by consecutive dissociation of dON-cell complexes formed in 1 h at 37°C. Incubation of dON with cells led to the priming of new high-affinity binding sites and an increase of the binding constant to a level characteristic of high-affinity ligand-receptor interactions (10⁹ M^–1). High-affinity receptor-mediated binding preceded internalization of dON. Lipofection increased the binding constant and the number of binding sites severalfold but had virtually no effect on the temporal pattern and the extent of dON internalization.__________Translated from Molekulyarnaya Biologiya, Vol. 39, No. 2, 2005, pp. 235–244.Original Russian Text Copyright © 2005 by Timofeev, Borovkova, Nydenova, Akhlynina, Shmarov, Grineva.     

Prognosis of accumulation of 137Cs and 90Sr in the herbage of the main types of the Belarus Polessje meadows using agrochemical soil properties

On the basis of long-term stationary experience it was established that the minimum accumulation quantities for 137Cs and 90Sr in the herbage of the dry, lowland and flood-plain types of the Belarus Polessje meadows contaminated with Chemobyl radionuclides are determined when the optimum of basic agrochemical soil properties is achieved with application of the scientifically reasonable protective measures. For remote prognosis of radionuclide contents in natural and cultural meadow herbage the use of transfer factors (TFa, (Bq/kg)(kBq/m2)) based on the complex agrochemical parameters--agrochemical cultivation soil index (Icd) and basic saturation degree (V, %), which take into account some soil characteristics simultaneously, is a streamlined approach. This paper provides the equations of linear and multiple regressions, which can be used to calculate the transfer factors for 137Cs and 90Sr uptake and the herbage contamination degree for the main types of meadows of the region, that will allow reducing the volume of forage production (hay, green bulk), which is not adequate to established permissible levels: "Republican allowable levels of the contents of 137Cs and 90Sr in agricultural raw material and forages".     

The temperature dependence of high-resolution 1H NMR spectra of Rhodobacter sphaeroides photosynthetic reaction centres in a temperature range of 25-40 degrees C

High-resolution 1H-NMR spectra registered within a temperature range of 25-40 degrees C revealed a nonmonotonous dome-shaped temperature dependence of the ratio between integral NMR signal intensities determined at ppm intervals 2.5-4.5 and 0.2-2.5 with a maximum at 30 degrees C. This may be due to RC structural changes accompanying the temperature rise and accelerating the recombination reaction between oxidized bacteriochlorophyll and reduced primary quinone at temperatures above 30 degrees C.     

Binding of unnatural alpha,beta-oligocytidylates with DNA duplexes

Binding of short fluorescently labeled AT-containing DNA duplexes with modified oligocytidylates is studied. The latter are modified to contain unnatural alpha-anomers along with natural beta-nucleotides; the nucleotide composition is selected according to putative pattern of unconventional triplex formation between duplex and oligomer bases. Nondenaturing gel electrophoresis is used to study complexation of fluorescent duplexes with cytidyl oligomers and oligocytidylate self-association at low temperatures. A DNA duplex of random AT composition is shown to bind with an excess of the corresponding oligocytidylate in 0.1 M Tris-HCl in the presence of Mg2+. Binding is observed at neutral pH values, while more basic pH (8.0) prevents complexation of the AT duplex and oligocytidylate. Contrary to oligonucleotides of irregular composition, a regular dA30:dT30 duplex does not bind with the dC strand. It is also shown that alternating self-complementary duplex d(AT)16 and oligocytidylate d(CbetaCalpha)15 do not form complexes, and poly-dC self-associates are formed instead. The effect of 2'-O-methylation of the third strand on complex formation and self-association is also analyzed. The results suggest that a modified oligocytidylate binds with a random-composition duplex, albeit with lower efficiency.     

A simple synthesis of 3β-acetoxy-20-oxomethylpregn-5-ene and 3β-acetoxy-20-hydroxymethylpregn-5-ene

3β-Acetoxy-20-oxomethylpregn-5-ene and 3β-acetoxy-20-hydroxymethylpregn-5-ene were synthesized from (22R, 23R)-sitost-5-ene-3β,22,23-triol in 66% overall yields.     

A heterogeneous computing environment to solve the 768-bit RSA challenge

In December 2009 the 768-bit, 232-digit number RSA-768 was factored using the number field sieve. Overall, the computational challenge would take more than 1700 years on a single, standard core. In the article we present the heterogeneous computing approach, involving different compute clusters and Grid computing environments, used to solve this problem.     

ICR heating in ion separation systems

A systematic procedure for analyzing the physical processes that govern ICR heating in systems for ion separation is developed. The procedure is based on an analytic model of an rf antenna generating rf fields within a plasma column in a magnetic field and includes such issues as the calculation of rf fields, examination of the ICR interaction of ions with these fields, and determination of the distribution function of the ion flow at the exit from the ICR heating system. It is shown that, even in ICR heating systems with easily achievable parameter values, ions with appreciably different masses can be efficiently separated by energy.     

Use of direct solid-phase immunoenzyme analysis for assessing the immunological activity of a vaccine against tick-borne encephalitis

A high correlation between the current index of the effectiveness of tick-borne encephalitis vaccine, its protective activity in mice, and the results of the direct solid-phase enzyme-immunoassay has been established, which permits the use of this assay as an auxiliary method for the immunological evaluation of newly prepared commercial purified tick-borne-encephalitis vaccine.