Intra- and intermolecular recombination of test plasmids in K12 Escherichia coli cells carrying an RTF derivative of the R1drd-19 plasmid

The RTF derivative of the plasmid R1drd-19 was found to stimulate recombination of the tester plasmids in a recB mutant of Escherichia coli K12. The frequency of intramolecular recombination is increased 3.5 and 20-fold, as compared to the one in rec+ and rec- strains, respectively. The frequency of interplasmid recombination is enhanced 4 and 9-fold, respectively. Considerable heterogeneity of the recombination products of the tester plasmid intramolecular recombination in recB-/RTFR1-19 strain has been revealed. It is hypothesized that a "recombinase" encoded by Rldrd-19 plasmid determines a new minor pathway in recB- (Rec P) which differs in activity and, perhaps substrate specificity from the main Rec BCD pathway.     

Revision of the structure of ristomycinic and actinoidinic amino acids

The structures of ristomycin and actinoidine amino acids described earlier were revised. Crystalline derivatives of the amino acids and the products of their oxidation were prepared. The study on the spectral properties of the compounds showed that ristomycin and actinoidine amino acids had the structures of 3-(2'-hydroxy-5'-glycyl-phenoxy)-4-methyl-5-hydroxyphenylglycine and 2-(2'-hydroxy-5'-glycyl-phenyl)-3,5-dioxyphenylglycine respectively. They did not differ from deaminodicarboxylic acids prepared with ristocetin, vancomycin and actionoidine.     

Variability in host plant resistance of Sorghum to Striga Hermonthica infestation in West Africa

Fourteen elite sorghum lines were evaluated for their resistance to Striga hermonthica at three locations in Nigeria and Mali. Results showed that many of the lines especially MALISOR 84-1, SAMSORG 41, 97-SB-F5DT-64 (Keninkédié) and the check SRN 39 remained resistant to Striga in all locations with low emerged Striga counts, while SAMSORG 14 had the highest Striga infestation in all locations. Considerable variation in reaction to Striga infestation was observed on Séguètana, 97-SB-F5DT-63 (Wasa), 97-SB-F5DT-65, CMDT 38, CMDT 39 and CMDT 45 which were susceptible to Striga at Samaru, Nigeria but were resistant to Striga at both locations in Mali. Based on low Striga resistance and high grain yield, lines MALISOR 84-1, SAMSORG 41, 97-SB-F5DT-64, 97-SB-F5DT-65, CMDT 39 and SAMSORT 14 have been nominated for wider evaluation across more West African countries.     

The increasing mutagenic effect of nitrosoguanidine under the influence of modified bases during inhibition of repair AGT enzyme in mammalian somatic cells in vitro

Gene mutations were studied on human cells SL68, XP12BE and chinese hamster cells Blld-ii-FAF28C1237. All the cells were sensitive to purine base analogs and were characterized by a high rate of O6-alkylguanine-DNA-transferase (AGT) activity. Inhibiting AGT activity by O6-benzylguanine considerably increases the frequency of mutants induced by the alkylating agent MNNG. Transitions of the GC-->AT type are the dominant mutations in the coding region of the hprt gene. The mechanism of DNA lesion repair by the AGT enzyme differs significantly from the excision repair.     

Endogenous DNases as a Tool for Isolation of Nuclear Matrix: Critical Parameters of Nucleolysis

The degree of nucleolysis is of critical significance for isolation of nuclear matrix (NM) specifically enriched in transcribed DNA sequences, as demonstrated using an example of inactive (c-fos, c-myc, andC ) and active (p53, albumin, and28S rRNA) genes in resting hepatocytes. The optimal degree of nucleolysis is characterized by degradation of loop domains of chromatin, with the relatively uniform molecular weight distribution of DNA being preserved. Deviation from these parameters leads to nonspecific fragmentation of chromatin in various gene loci and isolation of NM samples nonspecifically enriched with or depleted of transcribed DNA sequences. Under optimal hydrolytic conditions, the transcribed chromatin is more resistant to endogenous DNase attack, which allows selective conservation of its association with the nuclear matrix     

DNA, RNA, and protein biosynthesis in cells of Yersinia pseudotuberculosis at various cultivation temperatures

Y. pseudotuberculosis cells cultivated at temperatures of 37 degrees C and 8 degrees C were found to be capable of incorporating exogenic precursors into DNA, RNA and protein. The linear growth of thymidine incorporation occurred during 8 hours of cultivation at 37 degrees C, then the amount of the incorporated label decreased. At 8 degrees C the level of thymidine incorporation into DNA gradually increased for 80 hours and longer, but not reaching the level of incorporation observed at 37 degrees C. The incorporation of uridine into RNA of Y. pseudotuberculosis cells reached its maximum after 4 hours of cultivation at 37 degrees C, at a lower temperature of cultivation the incorporation of uridine into bacterial cells was almost linear, though slower, and lasted for 20 hours. The content of radioactive alanine in Y. pseudotuberculosis protein increased during 16 hours of cultivation at a high temperature, while at 8 degrees C the growth of the incorporation level lasted for at least 40 hours. For all precursors under study the incorporation rate into the cell biopolymers at the initial stages of cultivation was higher at 37 degrees C, than at a lower temperature.     

Two common nonsynonymous paraoxonase 1 (<Emphasis Type="Italic">PON1</Emphasis>) gene polymorphisms and brain astrocytoma and meningioma

Background  

Human serum paraoxonase 1 (PON1) plays a major role in the metabolism of several organophosphorus compounds. The enzyme is encoded by the polymorphic gene PON1, located on chromosome 7q21.3. Aiming to identify genetic variations related to the risk of developing brain tumors, we investigated the putative association between common nonsynonymous PON1 polymorphisms and the risk of developing astrocytoma and meningioma.     

Long-term effects of graduated compression stockings on cardiorespiratory performance

The use of graduated compression stockings (GCS) in sport has been increasing in the last years due to their potential positive effects for athletes. However, there is little evidence to support whether these types of garments actually improve cardiorespiratory performance. The aim of this study was to examine the cardiorespiratory responses of GCS during running after three weeks of regular use. Twenty recreational runners performed three tests on different days: test 1) – a 5-min maximal effort run in order to determine the participants’ maximal aerobic speed; and tests 2) and 3) – a fatigue running test of 30 minutes at 80% of their maximal aerobic speed with either GCS or PLACEBO stockings at random. Cardiorespiratory parameters (minute ventilation, heart rate, relative oxygen consumption, relative carbon dioxide production, ventilatory equivalents for oxygen and carbon dioxide, and oxygen pulse) were measured. Before each test in the laboratory, the participants trained with the randomly assigned stockings (GCS or PLACEBO) for three weeks. No significant differences between GCS and PLACEBO were found in any of the cardiorespiratory parameters. In conclusion, the present study provides evidence that running with GCS for three weeks does not influence cardiorespiratory parameters in recreational runners.     

Influence of different F1-specific components of Yersinia pestis capsular antigen on cell-mediated immunity

The F1-specific components of Y. pestis capsular antigen, isolated by Baker's method, were shown to differ by their biological activity and the character of action on cell-mediated immunity factors, used in this study. Depending on the method of isolation, antigens could vary in the proportion of their components, which determined the specific features of the total preparations obtained in this investigation. Out of the four components under study having the same antigenic specificity, but different physico-chemical characteristics and genetically determined synthesis, only one component exhibited biological properties dominating in the secreted form of F1, more similar in their composition to protein Caf1. The other three components exhibited immunological activity on the level of unspecific protection in different ways, depending on the model, and influencing the outcome of the interaction "bacteria-macrophage". Lectin-like hemagglutinating and hemolyzing activity was shown by components not related to protein Caf1. The multi-component character of preparations F1 (Baker) and the individual activity of their components should be taken into consideration when using capsular antigen and different methods of its isolation for different aims.     

A molecular dynamics simulation study of human alpha-fetoprotein-derived peptide and its analogues. Influence of dielectric constant

A comparative study of the conformation dynamics of a series of heptapeptides: the human alpha-fetoprotein fragment LDSYQCT and its seven analogues has been conducted. The effect of the dielectric constant of medium on the dynamics of heptapeptide conformation is considered. It is shown that electrostatic interactions have a marked effect on several accessible conformations and the dynamics of the behavior of amino acid residues.