The effect of anabiosis autoinducers on the bacterial genome

The mutagenic activity of chemical analogues of microbial anabiosis autoinducers (the autoregulatory d1 factors of cell differentiation), which act to inhibit cell proliferation, to enhance cell tolerance, and to induce the transition of cells to anabiotic state, was studied using the Ames test. In the range of concentrations studied (0.1 to 100 micrograms/ml), alkyl-substituted hydroxybenzenes (AHBs) differing in hydrophobicity, i.e., methylresorcinol (C1-AHB) and hexylresorcinol (C6-AHB), as well as unsubstituted resorcinol, showed different growth-inhibiting and mutagenic effects. C6-AHB was found to inhibit the growth of Salmonella typhimurium TA100 and to induce its mutagenesis at a rate of 1.8 revertants/nmol. C1-AHB taken at low concentrations not only failed to inhibit bacterial growth but even stimulated it and exerted an antimutagenic effect. Unsubstituted resorcinol virtually did not influence bacterial growth and showed weak mutagenic activity. The growth-inhibiting effect of elevated C6-AHB concentrations correlated with the degree of the transition of the original phenotype producing S-type colonies to a phenotype producing R-type colonies. The role of AHB homologues, as microbial autoregulators with mutagenic activity, in the regulation and correlation of two processes (the phenotypic dissociation of microbial populations and the formation of resting microbial forms) is discussed. The accumulation of AHBs in senescent microbial cultures may induce adaptive mutations, change the expression of genes, and promote the development of minor cell subpopulations (phenotypes), thus providing for the adaptation of these cultures to varying environmental conditions.     

Cleavage of RNA in a hybrid duplex by E. coli ribonuclease H. III. Substrate characteristics of hybrid duplexes of RNA and oligodeoxyribonucleotides containing a bleomycin A5 residue

The effect of the bleomycin A5 residue linked to four-, eight-, and twelve-mer oligodeoxyribonucleotides on the substrate properties of their tandem and continuous (with or without unmodified octanucleotide effectors) hybrid duplexes was studied using E. coli RNase H. The bleomycin derivatives of oligodeoxyribonucleotides were shown to form hybrid duplexes with practically the same thermostability as those formed by unmodified oligodeoxyribonucleotides. The RNA in the bleomycin-containing hybrid duplexes is cleaved by the E. coli RNase H; however, the initial hydrolysis rate (v0) is 2.6-3.4-fold reduced for the continuous duplexes. In the case of tandem hybrid complexes, the effect of bleomycin on v0 was less pronounced. We hypothesized that steric factors play a key role in the bleomycin inhibition and effectors probably determine the substrate properties of such hybrid complexes. Of all the tandem systems studied, the RNA duplex with the bleomycin-containing tetranucleotide flanked with two effectors displayed the best substrate properties. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2002, vol. 28, no. 4; see also http://www.maik.ru.     

The detection of genome polymorphism in Stachys species using RAPD

Molecular genome analysis was for the first time carried out in the genus Stachys. RAPD analysis proved to be suitable for identifying the species-specific markers, studying the interspecific DNA polymorphism, and detecting the genetic changes that arise during in vitro culturing of Stachys sieboldii. In addition, RAPD was used for screening genetic variation in S. sieboldii regenerants obtained at various phytohormone concentrations. High cytokinin concentrations and multiple regeneration were shown to induce genetic changes detectable with RAPD patterns. High DNA polymorphism was demonstrated for two types of S. sieboldii callus cultures and for plants regenerated from a callus culture.     

The activity of xylose reductase and xylitol dehydrogenase in yeasts

The activity and the cofactor specificity of xylose reductase and xylitol dehydrogenase were studied in extracts of yeasts from the genera Candida, Kluyveromyces, Pachysolen, Pichia, and Torulopsis grown under microaerobic conditions. It was found that xylitol dehydrogenase in all of the yeast species studied is specific for NAD+; xylose reductase in the xylitol-producing species C. didensiae, C. intermediae, C. parapsilosis, C. silvanorum, C. tropicalis, Kl. fragilis, Kl. marxianus, P. guillermondii, and T. molishiama is specific for NADPH; and xylose reductase in the ethanol-producing species P. stipitis, C. shehatae, and Pa. tannophilus is specific for both NADPH and NADH.     

The accumulation and degradation dynamics of cyanophycin in cyanobacteria grown in symbiotic associations with plant tissues and cells

Five different artificial associations of cyanobacterial cells with the cells or tissues of nightshade and rauwolfia were studied. The associations grown on nitrogen-containing media produced heterocysts. Cyanobacterial cells in the associations retained their ability to take up bound nitrogen from the medium, to store it in the form of cyanophycin granules, and to use them in the process of symbiotic growth. The synthesis and degradation of cyanophycin granules in cyanobacterial cells were more active in the associations than in monocultures. In the symbiotic associations of Chlorogloeopsis fritschii ATCC 27193 with Solanum laciniatum cells and of Nostoc muscorum CALU 304 with the Rauwolfia serpentina callus, heterocysts were produced at 3- to 30-fold higher cyanophycin contents than in cyanobacterial monocultures. In contrast, in the association of N. muscorum CALU 304 with the Solanum dulcamara callus, heterocysts were produced at lower cyanophycin contents than in the N. muscorum CALU 304 monoculture. The degradation of cyanophycin granules in N. muscorum CALU 304 cells grown in associations with plant tissues or cells was subjected to mathematical analysis. The activation of cyanophycin degradation and heterocyst production in the associations N. muscorum CALU 304-R. serpentina and C. fritschii-S. laciniatum was accompanied by an enhanced synthesis of the nitrogen-containing alkaloids in plant cells. The data obtained suggest that an integrated system of nitrogen homeostasis can be formed in symbiotic associations. Depending on the growth stage of an association, its plant member can either stimulate the accumulation of bound nitrogen in vegetative cyanobacterial cells in the form of cyanophycin granules, or activate their degradation, or initiate the formation of heterocysts independently of the cyanobacterial sensory-signalling system.     

Radioprotective activity and toxicity of copolymer 2-methyl-5-vinyl pyridine with 2-methyl-5-vinylpyridinium-n-oxide

In experiments in mice, hamsters and dogs therapeutic radioprotective efficiency and toxicity of new water-soluble copolymer were studied. It was found that at intramuscular injection of the copolymer to dogs in a dose of 5 mg/kg 24 h after irradiation with a dose of 3.30 Gy (LD85/45) it showed pronounced therapeutic effect (68.1%). In mice and hamsters, the effect was less pronounced: 42-21% after irradiation with a dose of 8.0 Gy. The copolymer is low toxic substance and according to the State standards of Russian Federation belongs to the fourth class (harmless).     

Influence of N-palmitoylethanolamine on the phospholipid and fatty acid composition of rat liver in ischemia

The effect of N-palmitoylethanolamine (NPE, 10(-5) M) on the lipid peroxidation (LPO) processes, phospholipid and fatty acid content in the rat liver at perfusion and ischemia during the liver preservation was estimated. As early as at the 5th min of perfusion by cooled conserving solution "Eurocollins", LPO activation was determined. Simultaneously the content of lysophosphatidylcholine (LPC) and phosphatidylserine increased, the total cholesterol level decreased. The redistribution of saturated and unsaturated fatty acids quantity was detected. The addition of NPE into "Eurocollins" solution reduced the accumulation of malonedialdehyde and LPC, modified the fatty acids content. These effects, evidently, formed the basis of the protective action of NPE on the hepatic tissues under anoxia.     

Recognition of joy, anger, and fear by face expression in humans

Behavioral and neurophysiological characteristics of a visual recognition of emotions of joy, anger, and fear were studied in 9 young healthy men and 10 women. It was shown that these emotions were identified by subjects with different rate and accuracy; significant gender differences in recognition of anger and fear were found. Recording of visual evoked potentials (VEP) from the occipital (O1/2), medial temporal (T3/4), inferior temporal (T5/6), and frontal (F3/4) areas revealed differences (related with the type of emotion) in the latencies of P150, N180, P250, and N350 waves and in the amplitude of VEP components with the latencies longer than 250 ms. These differences were maximally expressed in T3/4 derivation. The subjects could be divided in two groups. The first group was characterized by increased VEP latencies and higher amplitudes of VEP components later than 250 ms in response to anger (in comparison with other types of emotions). These phenomena were observed in all the derivations but were most pronounced in T3/4. In the second group, only late P250 and N350 components had shorter latencies during recognition of fear. VEP amplitude variations related with the type of emotions were insignificant and were recorded in the occipital and frontal areas. The two groups of subjects also differed in psychoemotional personality characteristics. It is suggested that primary recognition of facial expression takes place in the temporal cortical areas. A possible correlation of electrophysiological indices of emotion recognition with personality traits is discussed.