A-Factor as a selective agent for isolation of the soil Gram-negative bacterium strain--the producent of an antibacterial antibiotic]

It was shown the stimulating role of A-factor on soil prokaryotes growth. Soil sample culturing on agar medium, containing A-factor, resulted in the colony forming units (CFU) increasing in comparison with culturing on the medium without this regulator. Gram-negative bacteria were the reason of CFU increasing; previously the effect of A-factor on bacteria of this group was not shown. Gram-negative rod bacterial strain No. 35 was isolated and shown that CFU number was approximately twice increased at A-factor concentration in agar medium 2 and 7 mcg/ml; high A-factor concentration up to 28 mcg/ml was not effective. Isolated strain No. 35 is the producer of antibiotic, effective against gram-positive bacteria.     

Positive selection is a general phenomenon in the evolution of abalone sperm lysin

Lysin is a 16kDa acrosomal protein used by abalone sperm to create a hole in the egg vitelline envelope (VE). The interaction of lysin with the VE is species-selective and is one step in the multistep fertilization process that restricts heterospecific (cross-species) fertilization. For this reason, the evolution of lysin could play a role in establishing prezygotic reproductive isolation between species. Previously, we sequenced sperm lysin cDNAs from seven California abalone species and showed that positive Darwinian selection promotes their divergence. In this paper an additional 13 lysin sequences are presented representing species from Japan, Taiwan, Australia, New Zealand, South Africa, and Europe. The total of 20 sequences represents the most extensive analysis of a fertilization protein to date. The phylogenetic analysis divides the sequences into two major clades, one composed of species from the northern Pacific (California and Japan) and the other composed of species from other parts of the world. Analysis of nucleotide substitution demonstrates that positive selection is a general process in the evolution of this fertilization protein. Analysis of nucleotide and codon usage bias shows that neither parameter can account for the robust data supporting positive selection. The selection pressure responsible for the positive selection on lysin remains unknown.      

Reconstruction of the properties of smooth-muscle cell sarcolemma on planar lipid membranes

A method is described for reconstruction of certain sarcolemma characteristics of smooth muscle cells in the small intestine of a rabbit on the planar lipid membranes (PLM). The method is based on the use of fusogenic properties of certain lipid preparations. The ultrasound dispergates of azolectin and egg lecithin in combined incubation with sarcolemma vesicles of smooth-muscle cells promote a 1.4-1.8-fold increase of the total ATPase activity of the sarcolemma. Cholesterol, dipalmithoil lecithin, total brain phospholipids, inhibit the ATPase activity. Sarcolemma vesicles preincubated with azolectin lyposomes in the ratio which induces maximum ATPase activation (sarcolemma protein: azolectin-1:6) interact intensively with PLM from azolectin. PLM modified in such a way is channel-conductive, sensitive to tetraethylammonium and sign of the applied voltage.     

Inducible surface proteins from some strains of Pseudomonas species bacteria while adapting to cobalt

The possibility of increasing resistance of some Pseudomonas strains to cobalt at adaptation to monotonous increasing its concentration was studied. Strains Pseudomonas fluorescens B5242 and Pseudomonas fluorescens B894 are capable to increase its resistance in such conditions via inducible synthesis of protective surface proteins. The molecular masses of such proteins were 55.0; 45.0 and 33.0 kDa for P. fluorescens B5242 strain.     

Structural and functional aspects of bacterial membranes and liposomes interactions

Effect of exogenous lipids on the morphology and enzymatic activity of Bacillus cereus B4368 membrane has been studied. Specific character of different lipids action on the membrane enzyme activity was found. This peculiarity had been taken into account by using liposomes in biological systems.     

Interaction of energized bacteria cells with particles of colloidal gold: peculiarities and kinetic model of the process.

It is found that the cells of Bacillus cereus B-4368 at energized state can concentrate the colloidal gold particles on their surface. It is shown that the process depends on metabolic reactions proceeding on the plasma membrane. The inhibitory analysis permits to suppose that the metal concentration is due to the functioning of ATP-dependent generator of the transmembrane potential, apparently, of proton ATPase. Kinetic characteristics of the process show the presence of an intermediate state in the formation of biomineral aggregates. A kinetic model of the studied process is suggested which describes the experimental data well.     

Interaction of the glycoprotein from the Bacillus pumilis cell wall with liposomes

The methods of centrifugation and gel-filtration on Sephadexes G-50 and G-150 were used to study the interaction of Bacillus pumilis cell wall glycoprotein component having the molecular weight of 50 kDa (GP-50) with lyposomes from bacterial lipids. GP-50 is shown to sorb on such liposomes and disturb their barrier properties inducing yield of low-molecular label. GP-50 exerts no effect on properties of liposomes from egg lecithin. Electrostatic forces are supposed to play a decisive role in initial acts of GP-50 interactions with lipid phase of microbial envelopes.     

Obtaining bioluminescent bacterial strains for detection of thallium ions

The possibility of Alcaligenes eutrophus T1 luxphenotype creation by temperature induced mutagenesis has been shown. These mutants are able to emit light after induction by thallium ions. This biological method of thallium detection possesses high specificity and sensitivity (0.5 microM of metal). Such microbial cells can be used to quantify bioavailability of thallium part in the environment.     

Search for A factor-dependent variants in actinomycete population

A study of 28 nocardia-like, asporogenous, and oligosporous spontaneous morphological variants belonging to 23 species of streptomycetes revealed five strains producing regulators of the A-factor group. Streptomyces griseus 1439, which forms aerial mycelium and spores only in the presence of exogenous A-factor was used as the test strain. Among the 28 spontaneous variants, three new A-factor-dependent strains were revealed, which represented the species Streptomyces griseus, S. citreofluorescens, and S. viridovulgaris subsp. albomarinus. These weakly differentiated variants id not produce A-factor and behaved as its recipients, responding by changes in their morphological characteristics at a concentration of this regulator in the medium of 0.01 microgram/ml and higher. The original collection strains in whose populations the variants were selected produced substances of the A-factor group. The A-factor-dependent variants differed in the level of the regulator required for maximal expression of the morphological characteristics were shown: it was necessary to introduce the A-factor at a concentration of 1 microgram/ml for S. citreofluorescens and S. viridovulgaris subsp. albomarinus and at 10 micrograms/ml for S. griseus.