Site-directed mutagenesis in the uracil-repair system. Preparation of mutated forms of human alpha 2 interferon

The mutant forms of human IFN-alpha 2 gene are obtained by oligonucleotide-directed mutagenesis with the use of uracil-repair system. To intensify the process the procedure of the uracil-containing DNA template preparation is modified. It was determined that when mutagenesis is performed in the uracil-repair system the yield of the process depends on the mutant DNA-strand in vitro synthesis efficiency. It is shown that the stability of the 5'-end primer-template complex and the level of the endogenic primers elongation are the basis factors, that determine induction mutations.     

Kemantane pharmacokinetics in rats

Pharmacokinetics of novel immunostimulating drug kamantane was studied by using gas-liquid chromatography in experiments on rats. It was found that kemantane biotransformed rapidly after oral administration with the forming of active metabolite. Kemantane and its metabolites are distributed rapidly from the blood to organs. The drug is eliminated from the organism of rats as metabolite.     

Regulation of apolipoprotein expression]

Recent data and concepts on the structure and functioning of apolipoprotein genes as well as on the role of hereditary factors in pathogenesis of atherosclerosis are reviewed. The most important variants of inherited disorders in the system of apolipoproteins promoting the development of atherosclerosis are considered. Special attention is paid to the RFLP of apolipoprotein genes which serves as a peculiar genetic background, increasing probability of the atherosclerosis development in certain individuals.     

A model system for the study of repair of DNA double-strand breaks in Saccharomyces cerevisiae

The efficiency of "LiCl transformation" in Saccharomyces cerevisiae haploid cells by an autonomously replicating pLL12 plasmid carrying yeast LEU2 and LYS2 genes is increased (by an order or more) when the plasmid is linearized by the restriction endonuclease XhoI cleavage of a unique site in LYS2 gene. Transformants were selected on the medium lacking leucine. This phenomenon has been shown to be a result of recombinational repair of double-strand breaks (DSB) of plasmid DNA stimulated by a restriction endonuclease. The kinetic data have shown the process of plasmid DNA DSB repair to consist of two phases. The completion of the first phase occurs during an hour and the second phase occurs in 14-18 hours. DNA double-strand gaps (the deleted sequences of plasmid LYS2 gene in DSB region) with maximal length of 2-2.5 kb are repaired with the same efficiency as DSB. The genetic control of the recombinational repair of plasmid DNA DSB has been studied.     

Neurospecific and neuron-specific enolase levels in human nerve tissue at early stages of embryogenesis

Neurospecific and neuro-nonspecific isozymes of glycolytic enzyme enolase known to be molecular markers of neuronal and glial cells respectively were isolated from human brain. Using immunoenzyme assay, the content of these proteins was measured in the brain of 7-13-week human embryos and adult subjects. The content of both isoenzymes gradually increases attaining constant level in 10-13-week embryos. Relative content of neuro-nonspecific enolase in the brain of 10-13-week embryos is 1 1/2 times higher than that in adults, whereas the content of neurospecific enolase amounts only to 2% of its level in the adult brain.     

Ontogenetic features of autonomic homeostasis in children according to the data of variation pulsometry

A method of variation pulsometry was used to determine the vegetative homeostasis state in 20 children aged from 4 to 14. Normotonic type of the cardiac rhythm regulation was observed in a group of children aged 4-5. In children aged 12-14 the effect of sympathetic area of the vegetative nervous system decreased while the effect of the parasympathetic one increased. The tension index, effect of the humoral regulation channel and the degree of cardiac rhythm control centralization decreased.     

Loss of CpG dinucleotides from DNA. VI. Methylation of mitochondrial and chloroplast genes

From nucleotide sequences of mitochondrial and chloroplast genes the probable frequency of the CpG----TpG + CpA substitutions was determined. These substitutions may indicate the level of prior DNA methylation. It was found that the level of this methylation is significantly lower in mitochondrial DNA (mtDNA) and chloroplast DNA (chDNA) than in nuclear DNA (nDNA) of the same species. The species (taxon) specificity of mtDNA and chDNA methylation was revealed. A correlation was found between the level of CpG methylation in nDNA, and mtDNA and chDNA in different organisms. It is shown that cytosine residues in CpG were not subjected to significant methylation in the fungi and invertebrate mtDNA and also in the algae chDNA. In contrast, the vertebrate mtDNA bears the impress of CpG-supression, which is confirmed by direct data on methylation of these DNA. Here the first data on the possible enzymatic methylation of the plant mtDNA and chDNA were obtained. It was shown that the degree of CpG-suppression in the 5S rRNA nuclear genes of lower and higher plants is significantly higher in the chloroplast genes of 4,5S and 5S rRNA. From data on pea chDNA hydrolysis with MspI and HpaII it was established that in CCGG sequences this DNA is not methylated. The role of DNA methylation in increasing the mutation rate and in accelerating the evolutionary rates of vertebrate mtDNA is discussed.