Role of the NS gene in regulating the synthesis of RNA-segments of the influenza A virus

To find the role of any influenza virus gene in regulation of the RNA-segments replication the transfer of ts-mutants to nonpermissive temperature on the late step of infection has been used (shift-up). The mutants having impaired the NS or NP-genes have been obtained and studied. The transfer of mutants to partially nonpermissive conditions (when the amount of replication is decreased, but it still continues) results in the distinct return to the early mode of replication in ts-mutant with the mutation in NS-gene. This suggests the NS-gene role in replication of viral RNA-segments, in particular, in the switch from the "early" stage of replication to the "late" one. In NP-gene mutant only the decrease in general replication takes place without the shift to "early" replication mode.     

Hybrid vectors for the cyanobacterium Anacystis nidulans R2, containing the plasmid pUB110 from Staphylococcus aureus

The recombinant vector plasmids were constructed having the DNA of pUB110 plasmid (4,5 kb, KmR) from Staphylococcus aureus inserted into the cryptic plasmids pANS (8 Kb) and pANL (48,5 kb) of cyanobacterium Anacystis nidulans R2. The hybrid plasmids transform cyanobacterial cells to Km-resistance with high efficiency. The plasmid pBS20, containing the complete sequence of pANS and pUB110 DNA, transforms Bacillus subtilis rec E4 protoplasts being, however, unstable in bacilli cells and disintegrates deriving a parent pUB110 plasmid.     

Composition and structure of the antibiotic polypeptide 308-I from Actinomadura recticatena

Antibiotic 308-I isolated from Actinomadura recticatena and the products of its degradation were studied with the methods of electron impact mass spectrometry, chemical ionization with ammonia, field desorption and ion extraction from solution under atmospheric pressure. It was shown that by its composition and structure antibiotic 308-I was identical to antibiotic BBM-928 A.     

Dependence of Ca outflow and depression of frog myocardium contraction on ryodipine concentration

The effect of ryodipine on calcium outflow from tissues, on contraction force, the duration of action potentials and the relaxation phase time-constant in the contraction cycles of myocardial strips was studied using frog heart preparations. It was found that calcium outflow (delta Ca) as a function on ryodipine concentration can be represented as: (formula; see text) A linear correlation exists between Ca2+, contraction blocking and the shortening of the action potential in the presence of various ryodipine concentrations. Ryodipine (10(-5) mol/l) decreased the relaxation time-constant by about 20% as compared to controls. It was concluded that calcium outflow from myocardial tissues in response to ryodipine is due to blockade of calcium entry into the cells and their output through the Na+--Ca2+ exchange system. Frog heart myocardial contractions are essentially under the control of calcium entry through sarcolemmal calcium channels.     

A modified method of isolation of "tight" 70S ribosomes from Escherichia coli highly active at different stages of the elongation cycle

The functional activity of the wide-spread "tight" 70S ribosomes is usually equal to 55-80%. We show here that the inactive fraction of this type of ribosomes is virtually blocked by residual endogenous RNA's. These RNA's are shown to be removable by introducing an additional stage in the isolation procedure including: 1. short heating (15 min, 37 degrees C) of "tight" 70S under dissociation conditions, i. e. in a buffer containing 3 mM MgCl2 and 200 mM NH4Cl; 2. washing off endogenous RNA's on a sucrose density gradient in the same buffer; 3. final selection of purified "tight" 70S on the sucrose gradient containing 5 mM MgCl2 and 50 mM NH4Cl. "Tight" 70S ribosomes isolated by such a procedure are 90-100% active with respect to tRNA binding (including the factor-dependent one), peptide bond synthesis and translocation.     

The physiologic role of pyocyanine synthesized by Pseudomonas aeruginosa

The physiological role of pyocyanine for Pseudomonas aeruginosa was studied. Its synthesis was shown to commence at the retardation growth phase. Pyocyanine was accumulated only in the growth medium. The addition of 2,6-dichlorophenolindophenol accepting the reducing equivalents from coenzyme Q and transferring them to cytochrome c inhibited the pigment accumulation. This was indicative of the connection between pyocyanine synthesis and the level of the reducing equivalents in the cells. Pyocyanine did not accept the reducing equivalents from coenzyme Q in the respiratory chain of P. aeruginosa. Only reduced pyridine nucleotides served as substrates for pyocyanine in the reaction of autooxidation. The kinetic parameters of this reaction and the affinity of NADH dehydrogenase for the substrate were measured. The kinetic data were analysed to show that, under the physiological conditions, pyocyanine could not apparently compete with the respiratory chain for the reducing equivalents and hence directly regulate the level of NAD(P)H in P. aeruginosa cells. In order to keep the oxidising activity at a level necessary for the cells, the latter decreased the content of the reducing equivalents either by synthesizing pyocyanine or owing to the activity of cyanide-resistant oxidase. These processes of releasing the reducing equivalents are in a reciprocal relationship.     

Reaction of anti-HLA-B monoclonal antibodies with envelope proteins of Shigella species. Evidence for molecular mimicry in the spondyloarthropathies

Immunologic cross-reactivity between enteric bacteria and the HLA-B27 protein may play a role in the etiology of Reiter's syndrome and reactive arthritis. The reactivity of two anti-B27 mAb (B27M1 and B27M2) with envelope proteins of Shigella flexneri isolated from Reiter's syndrome patients was studied by Western blot analysis. Proteins with an apparent Mr of approximately 36 and 23 kDa reacted with both mAb in ascites. mAb against related HLA class I Ag B7 and B40 did not react with the 23 kDa protein. Relatively high concentrations of antibody were required for reactivity, suggesting a low affinity interaction. Additional evidence for cross-reactive epitopes was obtained by ELISA against whole envelope and by using unsolubilized envelope to inhibit binding of M1 and M2 to B27-positive cell lines, as measured by quantitative flow microfluorimetry. The presence of cross-reactive proteins was not related to the presence of the intact virulence-associated plasmid or the invasive phenotype. Two Shigella sonnei isolates not implicated as causative agents of Reiter's syndrome or reactive arthritis showed a similar pattern of cross-reactivity. These results indicate that cross-reactive epitopes may be present on "arthritogenic" bacteria, but their presence is not a unique feature of such strains and is not the sole factor in induction of arthritis in B27-positive individuals.     

Changes in the characteristics of human granulo- and monocytopoiesis and the activity of stromal precursor cells in acute hypobaric hypoxia

10 healthy men underwent a 48 hour acute hypobaric hypoxia in the "Taba?" climate chamber imitating conditions of an altitude of 4.00 m. above s.l. The "ascent" and "descent" took 30 minutes each. Blood and bone marrow samples were taken before entering the chamber and immediately after leaving it. A decrease in colony-forming capacity of granulo- and monocyte and fibroblast precursors was shown, along with an increase in functional activity of circulating monocytes and monocyte precursors in bone marrow. A possible role of changes in granulo- and monocytopoiesis and in stromal cells is discussed in relation to the increased morbidity and decreased cicatricial and bone tissue reparation in the mountains.