[Isolation and characteristics of plasmids from Aeromonas].

Fourteen out of fifty-two examined strains of Aeromonas contain plasmids. One of them determines the resistance to tetracycline, streptomycin, and chloramphenicol. The pAs30 plasmid, 53 t.

Theoretical and experimental study of DNA helix-coil transition in acidic and alkaline medium.

The theoretical approach to the calculation of the influence of selective binding of small ligands on DNA helix-coil transition has been described in the previous paper (Lando D. Yu., J.

[Temperate SM phage from Pseudomonas aeruginosa as a vector for cloning genetic information].

The recombinant bacteriophages with the genomes containing the DNA fragments of bacteria Erwinia chrysanthemi, including the pectatelyase gene, were constructed on the base of Pseudomonas aeruginosa temperate bacteriophage SM. The gene transferred into Pseudomonas aeruginosa PAO1 cells by transfection is expressed in the new bacterial host. The restriction maps of the recombinant bacteriophages are constructed and the position of an insert is defined.

[Localization of prophage SM of Pseudomonas aeruginosa in the chromosome of host cells].

Pseudomonas aeruginosa PAO SM-prophage was localized on the chromosome between thr-9001 and pur-66 locuses on 42-43 min of chromosomal genetic map. The location of prophage was identified on the basis of prophage linkage with the above-mentioned markers and confirmed by the purine, hypoxanthine and threonine deletions in course of thermoinduction of SM cts6 prophage from lysogens. The decrease for two orders in lysogenization frequency of thr mutants by SM bacteriophage suggests the integration of SM prophage in these cells into some other region of chromosome.

[Restriction analysis of DNA from phage SM of Pseudomonas aeruginosa].

The DNA of temperate phage SM P. aeruginosa has one PvuII site, two BamHI sites, three HindIII sites and five EcoRI sites. Using these restrictases the physical map of the phage genome has been constructed.

[Control of lysogeny and a genetic map of the temperate phage SM of Pseudomonas aeruginosa].

76 mutants with impaired ability to lysogenize host cells were isolated in SM phage after mutagenesis using several chemical mutagens. By means of complementation test, these mutants were distributed into two groups, cI and cII. The mutants of the cI group were similar phenotypically to the cI mutants of phage lambda defective in synthesis of repressor.

[The role of te transposition of Tn1000 from Flac+-plasmid into chromosome of Erwinia chrysanthemi in the formation of Hfr-type donors].

Based on the data of stability of the donor state of Hfr-like strain Erwinia chrysanthemi VY1-10 in RecA+ and RecA- cells, it can be suggested that the donor properties of the strain are mediated by the presence of the genetic homology region which occurred as a result of transposition of the Tn1000 from the Flac+ plasmid into the chromosome of E. chrysanthemi. Tn1000 may be transposed into several sites on the chromosome of E.

[The effect of R-plasmids on the reproduction of Pseudomonas aeruginosa phage SM].

The inheritance of plasmids Rms163 and R74 by Pseudomonas aeruginosa strain PAO hs been shown to effect the reproduction of a temperature bacteriophage SM. The decrease in plating efficiency of bacteriophage on Pseudomonas aeruginosa PAO (rms163) lawn is explained by the high degree of cell lysogenization by bacteriophage. Plasmid R74 inhibits bacteriophage SM propagation ultimately, evidently due to interruption of definite stages in vegetative development of bacteriophage by the products of plasmid specific genes.

[Complementation and the physiological characteristics of the ts mutants of Pseudomonas aeruginosa phage SM].

Seventy three temperature-sensitive mutants of Pseudomonas aeruginosa SM phage have been obtained using different mutagens and assigned to thirteen complementation groups. Representative mutants of each group have been studied with the aim of characterizing tentatively the time of genes expression in infected bacteria. Two genes appear to function during the first minutes after infection, whereas the remaining genes are needed for late functions.

[Conjugative R-plasmid of facultative methylotrophic bacteria Pseudomonas sp. M].

50 Md conjugative plasmid, designated pM3, has been found in the cells from natural isolates of Pseudomonas sp M. The plasmid determines the resistance to tetracycline and streptomycin and is capable of conjugative transfer between the cells of Pseudomonas and Escherichia coli. The conjugative derivatives of pM3 deleted for 14 Md of molecular mass were isolated after acridine dyes treatment of cells harbouring plasmid pM3.

[Transducing activity of the temperate SM bacteriophage of Pseudomonas aeruginosa].

The temperate bacteriophage SM is not serologically related to the known transducing phages F116, G101, B3 of Pseudomonas aeruginosa. The strains with auxotrophic mutations within the wide ranges of the genetic map of P. aeruginosa strain PAO1 were used for studying the transducing activity of the SM phage.

[Dependence of the melting temperature of phage DNA on the GC pair content in a solvent with low ionic strength].

Base ratio of DNA from 21 bacteriophage of Pseudomonas was determined by chemical hydrolysis and paper chromatography. Obtained values of the GC pair content were compared with melting temperature of DNA in 0,1 X SSC. The content of GC pairs correlates with melting temperature by equation %GC = 2,53 (Tm - 53,4).

[Effect of selectively reacting ligands on the helix-coil transition of DNA. IV. Heat denaturation of DNA in an acid medium].

The DNA thermal denaturation in acidic medium has been investigated experimentally and theoretically. The formulae describing a dependence of the helix--coil transition parameters (melting temperature (Tm) and melting range width (delta T) on ionisation constants values of all kinds of DNA bases in the helix and coil regions and medium acidity have been obtained. Dependences Tm (pH) and delta T (pH) have been determined experimentally and calculated for different models of protonation.

[Biological properties and DNA nucleotide makeup of Pseudomonas bacteriophages].

Fifty-two bacteriophages active against Pseudomonas bacteria were isolated from nautral sources and their following properties were studied: the morphology of negative colonies, the spectrum of lytic action, and the susceptibility to certain chemical and physical factors. One phage was shown to contain lipids. The content of GC pairs in the DNA of the phages determined from the melting temperature varied within the range of 46 to 67%.

[Spectroscopic and photochemical properties of pigments bound to proteins].

Using gel-filtration and spectral-luminescent analysis properties of artificial chlorophyll-protein and chlorine-protein complexes on the basis of human serum albumin (HSA) were analysed. It has been shown that formation of joint complexes pigments - HSA does not induce essential changes in the spectral and energetic parameters of the pigment part of the complex. A change in the rate of photosensitized reduction of methylviologen (sensitizer-pigment) was found during the variation of the relative content of the pigment mixed with HSA.

[Pseudomonas putida PpG1 resistance to different bacteriophages].

Cris-cross resistance analysis has been accomplished for some Pseudomonas putida PpG1 mutants resistant to pf16, af, tf and PMW phages. On the basis of the results, a formal scheme of the receptor sites for these phages on the bacterial cell surface was drawn. Study of the sensitivity of P.