The replication of Escherichia coli chromosome can be initiated by integrated ColE1-type plasmids

Summary When integrated in the chromosome of E. coli by site-specific recombination of , the ColE1 type replicator provokes the phenotypic suppression of CRT46 dnaA strain. The level of this suppression depends on the orientation of ColE1 replicator in the chromosome of bacteria. Integrative plasmids (intmids) coexist in both autonomous and extrachromosomal states in the same cell.     

Construction of recombinant plasmid carrying the lambda DNA fragment responsible for prophage integration.

The recombinant DNA molecules were constructed from plasmid RSF2124 and the EcoRI fragment of lambda DNA containing the genes responsible for prophage integration. The presence of these genes in recombinant plasmids was detected genetically. lambda int-gene was shown to be expressed in either orientation of insertion in the plasmid. We found that recombinant plasmid was able to integrate into chromosome of lambda lysogens. The integration of plasmid into host chromosome was demonstrated by contransduction of chromosome and plasmid markers using generalized transducer P1 and by specialized transduction with lambda phages.     

Plasma-coagulation hemostasis in physically active subjects during adaptation to physical exercise

Basic hemorheological and pro-and anticoagulatory characteristics were studied in athletes practicing cyclic sports and patients with venous thrombosis and arterial atherosclerosis. The results of factor analysis of the entire sample indicated that changes in the procoagulatory components of the plasma-coagulation hemostasis in athletes tend to decrease the coagulatory potential of the blood. The athletes displayed a decrease in the activity of natural anticoagulants (protein C and antithrombin III). A significant decrease in the parameters of blood viscosity mainly caused by a better red cell deformability was correlated with the changes in the procoagulatory and anticoagulatory components of the hemostasis; these changes were well balanced and may be considered predominant. Damage to the vascular endothelium and disturbances in the red cell microrheology were found to be the most important factors in the patients with peripheral arterial disease. Acute deep vein thrombosis was associated with a strong activation of procoagulatory components and dysfunction of natural anticoagulants.     

Enzymatic properties of immobilized beta-galactosidase from Curvularia inaequalis]

beta-Galactosidase (EC 3.2.1.23) from fungus Curvularia inaequalis was modified by active brilliant orange KH and adsorbed on DEAE-Sephadex A-50. The lactose hydrolysis was studied in a continous flow on the column packed with the immobilized enzyme. The pH and temperatures optima for the substrate hydrolysis by the immobilized enzyme were shown to remain unchanged. A certain destabilizing effect of the matrix on the enzyme resistance to hear denaturation was observed. The activation parameters of denaturation of the native enzyme as well as those of the dye-modified and immobilized preparations were determined.     

Stability of DNA duplexes containing GG, CC, AA, and TT mismatches

We employed salt-dependent differential scanning calorimetric measurements to characterize the stability of six oligomeric DNA duplexes (5'-GCCGGAXTGCCGG-3'/5'-CCGGCAYTCCGGC-3') that contain in the central XY position the GC, AT, GG, CC, AA, or TT base pair. The heat-induced helix-to-coil transitions of all the duplexes are associated with positive changes in heat capacity, DeltaC(p), ranging from 0.43 to 0.53 kcal/mol. Positive values of DeltaC(p) result in strong temperature dependences of changes in enthalpy, DeltaH degrees, and entropy, DeltaS degrees , accompanying duplex melting and cause melting free energies, DeltaG degrees, to exhibit characteristically curved shapes. These observations suggest that DeltaC(p) needs to be carefully taken into account when the parameters of duplex stability are extrapolated to temperatures distant from the transition temperature, T(M). Comparison of the calorimetric and van't Hoff enthalpies revealed that none of the duplexes studied in this work exhibits two-state melting. Within the context of the central AXT/TYA triplet, the thermal and thermodynamic stabilities of the duplexes in question change in the following order: GC > AT > GG > AA approximately TT > CC. Our estimates revealed that the thermodynamic impact of the GG, AA, and TT mismatches is confined within the central triplet. In contrast, the thermodynamic impact of the CC mismatch propagates into the adjacent helix domains and may involve 7-9 bp. We discuss implications of our results for understanding the origins of initial recognition of mismatched DNA sites by enzymes of the DNA repair machinery.     

Genetic and phenotypic differences between thistle populations in response to habitat and weed management practices

Rapid evolutionary change is increasingly being recognized as commonplace, but the evolutionary consequences for species and ecosystems under human‐induced selection regimes have not been explored in detail, although many species occur in such environments. In a common garden experiment and with amplified fragment length polymorphism markers, we examined whether genetic differentiation has taken place between spatially intermixed populations of creeping thistles Cirsium arvense (Asteraceae) collected from a natural habitat (maritime shores), a semi‐natural habitat (road verges) and arable fields under two management regimes: conventional and organic farming. Populations of C. arvense have altered genetically and locally adapted their growth patterns with changed land use. Although plants from different habitats showed similar total biomass production, shoot and root production was higher for maritime populations, suggesting selection for increased competitive ability. Competitive ability then declined in the order semi‐natural, conventional farms and organic farms. Thistles in arable fields may be more selected for tolerance against disturbances from herbicides and mechanical weed control. In addition, early shoot sprouting and genetic analysis showed differentiation between plants originating from conventional farms and farms that were converted to organic 9–30 years ago, suggesting some adaptation to altered crop cultivation practices. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 797–807.     

Function of external respiration in patients with systemic scleroderma (according to roentgenopneumopolygraphic data)

External respiratory function was investigated in 33 patients with systemic scleroderma+ using roentgenopneumopolygraphy (RPPG). Respiratory changes consisted in diffuse and regional ventilation disturbance (after emphysematous, hypoventilation or mixed type), disorders of respiratory kinetics of the diaphragm, ribs and mediastinum. External respiratory functional disturbance showed direct correlation with the patients' age, period of disease and a degree of pathological activity. The type of external respiratory functional disturbance was unchanged during observation over time. The use of exercise testing showed the presence of signs of latent ventilation insufficiency in most of the patients.