A novel nucleic acid-binding protein that interacts with human rad51 recombinase.

Using the yeast two-hybrid system, we isolated a cDNA encoding a novel human protein, named Pir51, that strongly interacts with human Rad51 recombinase. Analysis in vitro confirmed the interaction between Rad51 and Pir51. Pir51 mRNA is expressed in a number of human organs, most notably in testis, thymus, colon and small intestine. The Pir51 gene locus was mapped to chromosome 12p13.1-13. 2 by fluorescence in situ hybridization. The Pir51 protein was expressed in Escherichia coli and purified to near homogeneity. Biochemical analysis shows that the Pir51 protein binds both single- and double-stranded DNA, and is capable of aggregating DNA. The protein also binds RNA. The Pir51 protein may represent a new member of the multiprotein complexes postulated to carry out homologous recombination and DNA repair in mammalian cells.     

Synthesis of new 1-alkyl-, 1-benzyl-, and 1-aryloxyethyl-substituted 4,5-dichloroimidazoles and their antimicrobial,protistocidal, and fungistatic properties

Previously unknown 1-alkyl-, 1-benzyl-, and 1-aryloxyethylderivatives of dichloroimidazoles and products of their structural transformation were synthesized from 4,5-dichloroimidazole or 2-methyl-4,5- dichloroimidazole using alkyl, benzyl or aryloxyethyl halides. These N-substituted compounds were shown to have a weak antibacterial activity against some pathogenic gram-positive and gram-negative bacteria (Staphylococcus aureus and Escherichia coli). At the same time, some of the obtained compounds demonstrated a significant protistocidal activity against Colpoda steinii, which can exceed in strength the activity of clinically used veterinary drug Baycox. Moreover, these compounds showed a pronounced fungistatic effect.     

Multiparticle computer simulation of photosynthetic electron transport in a thylakoid membrane

A method for multiparticle computer simulation of photosynthetic electron transport in a thylakoid membrane has been developed. The basic principles of this method were described previously. The method is used to describe the cyclic electron flow around photosystem I. The effects of size and shape of the reaction volume on the kinetics of interaction of a mobile carrier with a protein complex and the limited diffusion of reactants were studied. It was shown that the kinetic parameters of photosynthetic electron transport processes depend on the distribution of protein complexes in the membrane. It was shown that the limited nature of diffusion of plastoquinone molecules in the membrane leads to a tenfold decrease in the efficient diffusion coefficient. It was shown that the occurrence of two phases of dark reduction of photooxidized P700+ is due to a heterogeneous spatial organization of the thylakoid membrane of a chloroplast.     

Detection of the 5382insC mutation in the human <Emphasis Type="Italic">BRCA1</Emphasis> gene with fluorescent labeled oligonucleotides

Analysis of genetic predisposition to cancer provides valuable information for early cancer detection or even prevention. The 5382insC insertion in the BRCA1 gene is the most frequent mutation among those associated with high breast cancer risk in women of East European origin. A method for 5382insC detection with fluorescent labeled allele-specific oligonucleotides in the Duplex Scorpion format has been developed. The method can be used under real-time PCR conditions as well as under the conditions of end-point fluorescence measurement following regular PCR. The adequacy of the method was demonstrated in the study of the 5382insC mutation frequency in breast cancer patients. A total of 564 genomic DNA samples from breast cancer patients were screened. Eleven patients (1.95%) were found to carry the mutation under consideration in the heterozygous state. The 5382insC allele frequency in the breast cancer patient group was 0.0098. The method is appropriate in clinical practice to detect individuals at high breast cancer risk, as well as in large-scale population studies.     

Synthesis and cytotoxic properties of 4,11-bis[(aminoethyl)amino]anthra[2,3-b]thiophene-5,10-diones,novel analogues of antitumor anthracene-9,10-diones

We developed the synthesis of a series of thiophene-fused tetracyclic analogues of the antitumor drug ametantrone. The reactions included nucleophilic substitution of methoxy groups in 4,11-dimethoxyanthra[2,3-b]thiophene-5,10-diones with ethylenediamines, producing the derivatives of 4,11-diaminoanthra[2,3-b]thiophene-5,10-dione in good yields. Several compounds showed marked antiproliferative potency against doxorubicin-selected, P-glycoprotein-expressing tumor cells and p53^?/? cells. The cytotoxicity of some novel compounds for P-glycoprotein-positive cells is highly dependent on N-substituent at the terminal amino group of ethylenediamine moiety. The cytotoxic potency of selected compounds correlated with their ability to attenuate the functions of topoisomerase I and telomerase, strongly suggesting that these enzymes are the major targets of antitumor activity of anthra[2,3-b]thiophene-5,10-dione derivatives.     

Catalytical properties of <Emphasis Type="Italic">Arthrobacter nicotianae</Emphasis> cells,a producer of glucose isomerase,immobilized inside xerogel of silicium dioxide

Arthrobacter nicotianae cells, producers of glucose isomerase, were immobilized inside xerogel of silicium dioxide, and properties of the resulted heterogeneous biocatalysts were investigated in the process of isomerization of monosaccharide (glucose and fructose). The glucose isomerase activity of the resulted biocatalysts was shown to be 10 U/g, on average, taking into account the loss of the activity upon the immobilization, which amounted to 50% of the cell activity in suspension. The rate of the fructose isomerization increased linearly in the range of 55–80°C with the temperature coefficient 1.3. The biocatalysts were stable in this range; they were rapidly inactivated, however, at increasing temperature. The half-pife time of inactivation was six to seven h and five min or less at 80 and 85°C, respectively. The half-pife time of inactivation of heterogeneous biocatalysts was 50–90 h in the periodic process of isomerization of 2 M monosaccharides at 60°C in the presence of the immobilized Arthrobacter nicotianae cells.     

Molecular Implications of Repeated Aggression: Th,Dat1, Snca and Bdnf Gene Expression in the VTA of Victorious Male Mice

Background

It is generally recognized that recurrent aggression can be the result of various psychiatric disorders. The aim of our study was to analyze the mRNA levels, in the ventral tegmental area (VTA) of the midbrain, of the genes that may possibly be associated with aggression consistently shown by male mice in special experimental settings.

Methodology/Principal Findings

The genes were Th, Dat1, Snca and Bdnf; the male mice were a group of animals that had each won 20 daily encounters in succession and a group of animals that had the same winning track record followed by a no-fight period for 14 days. Increased Th, Dat1 and Snca mRNA levels were in the fresh-from-the-fight group as compared to the controls. Increased Th and Dat1 mRNA levels were in the no-fight winners as compared to the controls. Significant positive correlations were found between the level of aggression and Th and Snca mRNA levels.

Conclusions

Repeated positive fighting experience enhances the expression of the Th, Dat1 and Snca genes, which are associated with brain dopaminergic systems. The expression of the Th and Dat1 genes stays enhanced for a long time.     

Multiparticle computer simulation of protein interactions in the photosynthetic membrane

The basic principles of the design of direct multiparticle models and the results of multiparticle computer simulation of electron transfer by mobile protein carriers in the photosynthetic membrane of a chloroplast thylakoid are presented. The reactions of complex formation of the plastocyanin with cytochrome f and the pigment-protein complex of photosystem I, as well as of ferredoxin with FNR and photosystem I are considered. The regulatory role of diffusion and electrostatic interactions as well as the effect of the shape of the reaction volume and ionic strength on the rate of electron transport are discussed.