Bacillus subtilis soil isolates: plasmid replicon analysis and construction of a new theta-replicating vector

We have searched for plasmids in a collection of 55 Bacillus subtilis strains isolated from various natural sources of the territory of Belarus. Twenty percent of the strains contained one or two plasmids of either 6-8 or approximately 90 kb. Small plasmids were shown to carry a rolling circle replicon of the pC194 type. Four out of the eight large plasmids contained a related theta replicon that has no homolog in databases as shown by sequence determination. A B. subtilis/Escherichia coli shuttle vector based on this replicon was constructed. It has a low copy number (6 units per chromosome) and is stably inherited in B. subtilis. It might thus be a useful tool for DNA cloning. These data extend previous observations, indicating that most of the small plasmids of B. subtilis replicate as rolling circles and belong to the pC194 family. On the contrary, large plasmids appear to form a large pool of theta-replicating determinants, since three different replicons have already been isolated from them.     

Genetic association between the apolipoprotein E (ApoE) gene alleles and various forms of Alzheimer's disease]

Allele epsilon 4 of the apolipoprotein E (APOE) gene is associated with higher risk of Alzheimer's disease (AD) in many, though not all, ethnic groups. The APOE allele and genotype frequency distributions were studied in 207 AD patients without cerebrovascular disorders, 62 AD patients with cerebrovascular disorders (combined AD), and 206 control individuals (ethnic Russians from the Russian population). The frequency of allele epsilon 4 in patients with early-onset and late-onset AD was three times higher than in control individuals (p < 0.000001). Compared with control people, patients with cerebrovascular disorders displayed a twofold higher frequency of allele epsilon 4; the difference between the two groups was significant (p = 0.0019). Relative risk of AD in carriers of allele epsilon 4 was five times higher than in carriers of alleles epsilon 2 and epsilon 3 (p < 0.000001). Allele epsilon 2 had a protective effect with respect to AD onset until 65 years of age (p = 0.015). Thus, APOE allele epsilon 4 proved to be a universal factor of early-onset, late-onset, and combined AD in ethnic Russians from Russia.     

Self-assembly of collagen type I molecules without telopeptides

The effect of temperature on the kinetics of formation of fibrils from rat tail collagen molecules devoid of telopeptides was studied. It was shown that the rats of fibril formation at 30 and 35 degrees C increases five- and eightfold, respectively, as compared with that at 25 degrees C. It was found that enthalpy of fibril denaturation at 30 degrees C is maximal for the collagen both with intact telopeptides and devoid of telopeptides. It was found that essential for the fibrilogenesis of type I collagen devoid of telopeptides are temperatures of 30 and 35 degrees C.     

Population Identification of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> Isolates from Russia

Using multilocus sequence typing (MLST), 22 Helicobacter pylori isolates from Russia have been characterized. All of the Russian strains were assigned to a single population, hpEurope.     

<Emphasis Type="Italic">A2144G</Emphasis> Is the Main Mutation in the <Emphasis Type="Italic">23S</Emphasis> rRNA Gene of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> Associated with Clarithromycin Resistance

To detect point mutations A2115C, A2143G/C, and A2144G in the 23S rRNA gene of Helicobacter pylori associated with resistance of the microorganism to clarithromycin, a new powerful way of analysis was used. This method involved the reaction of minisequencing followed by MALDI-TOF mass spectrometry of reaction products. In ten analyzed clarithromycin-resistant clinical isolates of H. pylori obtained in Russia, the resistance was found to be mediated only by mutation A2144G in the 23S rRNA gene.     

Relationship of the sensitizing and protective properties of pertussis antigens

When comparing delayed hypersensitivity (DN) to B. pertussis corpuscular antigens with the agglutinogenic composition of B. pertussis, as well as to its histamine-sensitizing, leukocyte-sensitizing, adjuvant and hemagglutinating activity, no correlation was detected between the specific sensitizing properties of these antigens and the serotype and studied nonspecific properties of B. pertussis. The DH level correlated with the protective activity of B. pertussis corpuscular antigens and the ultrasonic fractions of B. pertussis. The close correlation of these two phenomena suggest that DH-inducing and protective B. pertussis antigens are identical, though their action has different manifestations, depending on the method of administration of the antigen preparation. On these grounds a new method for evaluating the immunogenicity of B. pertussis antigens is proposed. This method consists in comparing the sensitizing activity of the antigen under test and that of the national standard.     

Action of cyclic adenosine monophosphate on the spleen antibody--forming cells of rabbits immunized with Escherichia coli]

Cyclic adenosine monophosphate (cAMP) parenterally injected to rabbits (immunized intraperitoneally with thymus-independent antigen of killed E. coli 0127/545) during January--April inhibited production of antibody-forming cells (AFC) in the spleen of these animals, and during May--June it increased the AFC count. Both the stimulating and inhibitory effect of cAMP was associated with the administration of the same doses of 25--250 microgram/kg. The nature of the cAMP effect on the production of the AFC depends on the initial immune response level. At the maximum immune response and in the absence of the dose-effect dependence cAMP inhibited the antibody formation, but when the immunological reaction was below the maximal level and in the presence of the dose-effect relationship cAMP increased the AFC production.     

Frequency of mutagen-induced sister chromatid exchanges in the course of 3 cell cycles

The induction of SCE by fotrine (0.125 and 0.250 microgram/ml) and thiophosphamide (5 micrograms/ml) during the first three cell cycles was studied in the Chinese hamster cells. No increase in the SCE number was observed after treatment with thiophosphamide and fotrine at the G2 stage (the first stage from the moment of fixation) as compared with the control variants. The maximal sensitivity of the cells to the SCE induction by the mutagens is marked at the G1 stage of the first cell cycle before the moment of fixation. The level of SCE remains approximately the same in the second cell cycle before the moment of fixation (20-32 h) and decreased down to the control level at the G1 stage of the third cell cycle (48-52 h).