Solid phase ligation of synthetic DNA fragments

A synthetic oligodeoxyribonucleotide (oligo) covalently bound by an internucleotide linkage to the succinylated Sephacryl S-500 support through 1.9-diaminononane spacer was used as starting compound to assemble the E. coli rec A promoter DNA fragment from synthetic oligos by means of T4 DNA ligase. The solid-phase assembly of the designed DNA was performed by two ways: stepwise ligation of two pairs of oligos (2 dyads) or simultaneous ligation of four oligos (tetrad). Both ways gave equal results with some preference in the tetrad case. The reliability of E. coli promoter DNA fragment assembly was demonstrated by cloning it in a plasmid vector and sequencing the cloned DNA by the solid-phase Maxam--Gilbert technique.     

1-Deaza and 3-deazapurines in the reaction of microbiological transglycosylation

Summary Substrate activity of 1- and 3-deazapurines in the reaction of microbiological ribo- 2-deoxyribosylation catalysed by purine nucleoside phosphorylase of viable cells ofE. coli BMT-1D/1A has been studied. Guanosine or 2-deoxyguanosine were used as donors. 1-Deazapurines are good substrates in both reactions; 3-deazapurines are very effective intransdeoxyribosylation but not intransribosylation. Benzimidazole is an excellent substrate in both reactions indicating that N(1) and N(3) are not essential for transglycosylation.     

Interaction of 3'-fluoro-3'-deoxyanalogs of a trimer of (2'-5')oligoadenylic acid with (2'-5')A3-antibodies: stereochemical aspect

Mouse antibodies to (2'-5')oligoadenylates were obtained by the immunization of animals with the (2'-5')oligoadenylic acid trimer conjugated with bovine serum albumin through a 2',3'-levulinic acid residue. Using radioimmunoassay, the reactivity of mouse polyclonal antibodies to the (2'-5')oligoadenylic acid trimer was studied for the trimer analogues containing 9-(3-deoxy-3-fluro-beta-D- xylofuranosyl)adenine and 3'-deoxy-3'-fluoro-adenosine in various positions of the chain. It was found that (a) the three-dimensional structure of short oligonucleotides is an important factor in the antibody recognition; (b) antibodies are more sensitive to modifications of the 5'-terminal and central ribose fragments of the (2'-5')oligoadenylic acid trimer; (c) the 3'-hydroxyl group plays a secondary role in the formation of the antigen determinant.     

Evaluation of the bioavailability of radionuclides from soil in cattle by an in vitro method

Factors have been examined which influence the radionuclides sorption from soil particles by fluid imitating rumen liquid of the cattle. It is noted that the extent of extractability of 137Cs from soil is influenced mainly by presence of potassium ions in modelling liquid. Major factor influencing the release of 90Sr from soil is pH value of the medium. The presence of heavy metals salts affected the release of radionuclides from soil particles. The data observed make it possible to use the modelling solutions to predict bioavailability of radionuclides from soil as well as to predict possible contamination of animal products (milk and meat).     

The influence of the composition of essential lemon oils on their antioxidant properties and the stability of the components

The antioxidant properties of various essential oils of lemon (Citrus limon L.) were studied by capillary gas liquid chromatography and compared with those of individual limonene and citral and their mixture in model systems. Some differences in resistance towards oxidation of the major components of lemon oils were ascertained and the synergetic effects in the antioxidant activity of the components and their stability were found.