[Features of genome expression of phage transposon D3112 of Pseudomonas aeruginosa in Escherichia coli bacteria: dependence of bacterial phenotype on copy number of D3112 genome]. / Osobennosti vyrazheniia genoma faga-transpozona D3112 Pseudomonas aeruginosa v bakteriiakh Escherichia coli: zavisimost' fenotipa bakterii ot chisla kopii genoma D3112.

Escherichia coli (RP4 :: D3112) bacteria manifest Tcs phenotype (thirty centigrade sensitivity), i.e. the cells do not divide and form colonies under conditions of lowered temperature (30 degrees C and lower), while cells grow normally at 42 degrees C. In this work it is demonstrated that replication-transposition of D3112 and the Tcs phenotype depend on no recA system of E.coli. Following events lead to the loss of the Tcs phenotype (in E.coli (RP4 :: D3112) cells survived after growing at 30 degrees C): occurrence of mutations in bacterial, phage and plasmid genomes, elimination of DNA of hybrid plasmid or RP4 DNA (a portion of DNA) as well as integration of the hybrid plasmid into bacterial chromosome. In the latter case, the E.coli (D3112) cells acquired the properties shared by the initial bacteria and those with the Tcs phenotype. Such clones are designated tcl (thirty centigrade low sensitivity), they are able to form colonies at 30 degrees C but their growth is more slow, they maintain instability at lowered temperature and continue to produce D3112 phage. The tcl clones in which replication-transposition of D3112 DNA in less effective than in the tcs clones are a suitable object for the study of genetic rearrangements caused by D3112 phage transposon. It is shown that either complete RP4 genome or its portion are comprised between direct repeats of D3112 and are built into various chromosomal sites, i.e. cointegrates are being formed. Two types of deletions are revealed: eliminating sites of RP4 plasmid adjacent to the left end of D3112 genome as well as deletions of the D3112 genome. It is demonstrated that alteration in the growth nature of E.coli, carrying D3112 DNA, at 30 degrees C depends on the copy number of D3112 per bacterial cell.

[Cloning of grisin resistance gene gsr and the study of its functioning in Streptomyces griseus Kr. strain]. / Klonirovanie gena ustoichivosti k grizinu gsr i izuchenie ego funktsionirovaniia v shtamme-produtsente Streptomyces Kr.

S. griseus Kr. is a commercial strain producing grisin, an antibiotic of the streptothricin group used as a feed additive. It was shown earlier that genetic instability of the strain was very high which was evident from a high frequency of nonreverting Grn- Grns mutants. With densitographic analysis of chromosomal DNA electrophoregrams and DNA-DNA hybridization it was revealed that the molecular basis of the genetic instability of the S. griseus strain was deletion of a DNA fragment about 20 kb in size containing a grisin resistance gene. The resistance gene designated as gsr was cloned to S. lividans TK 64 within the plasmid vector pIJ699. The restriction map of a cloned DNA fragment with a gsr gene was constructed and its similarity to that of a nat gene resistant to norseothricin, another streptothricin was observed. Introduction of a gsr gene within the multicopy plasmid pIJ699 into S. griseus 212, a highly productive strain synthesiing the antibiotic, led to an increase in its resistance and productivity. Proceeding from the preliminary data on possible linkage of a gsr gene and grisin biosynthesis genes, it appeared possible to use the cloned gene as a molecular probe in cloning the biosynthesis genes.

[Cloning and expression in Bacillus subtilis of the gene for neutral protease of Bacillus brevis]. / Klonirovanie i ékspressiia v Bacillus subtilis gena neitral'noi proteazy Bacillus brevis.

Plasmids pCB20 and pCB22 were used for cloning and expression of the Bac brevis 7882 neutral protease gene in Bac. subtilis cells. The protease-containing fragments of 13 and 14 kb were cloned in pCB20 plasmid based on replication region of Streptococci plasmid pSM19035. Expression of the gene was shown to take place in Bac. subtilis. Application of vegetative promoters of the previously identified expression unit EU19035 greatly increases the expression of the protease in Bac. subtilis. Bac. subtilis cells, expressing the gene of Bac. brevis neutral protease, do not sporulate, are considerably larger than the cells which do not contain the gene and form multicellular structures.

[Molecular cloning and the expression of the genes of amino acid biosynthesis of Corynebacterium glutamicum in Escherichia coli cells]. / Molekuliarnoe klonirovanie i ékspressiia genov biosinteza aminokislot Corynebacterium glutamicum v kletkakh Escherichia coli.

Cloning of genes for threonine and lysine biosynthesis from Corynebacterium glutamicum was performed in Escherichia coli cells using the plasmid vector lambda pSL5. The cloned genes are identified via complementation of thrB and lysA mutations. The gene complementing thrB of E. coli is located within a 4.1 kb EcoRI fragment of C. glutamicum chromosomal DNA. All the recombinant phasmids complementing the lysA gene of E. coli contain common 2.2 kb and 3.3 kb EcoRI C. glutamicum DNA fragments. The cloned DNA fragments hybridize with identical EcoRI fragments of C. glutamicum chromosomal DNA.

[Effects of different concentrations of chloramphenicol on RNA synthesis in E. coli]. / Vliianie razlichnykh kontsentratsii khloramfenikola na sintez RNK v kletkakh E. coli.

In the presence of 2 microgram/ml chloramphenicol the rate of total RNA synthesis increases 1,6-fold, while that of rRNA synthesis--2,5--3,0-fold. Other ribosomal antibiotics, e.g. oxytetracycline, neomycin and puromycin, as well as chloramphenicol stimulate the synthesis of RNA while not causing a complete inhibition of the protein synthesis. Intensive stimulation of the rate of rRNA synthesis with low concentrations of chloramphenicol may be due to a decrease of intracellular concentration of guanosine-5'-diphosphate, 3'-diphosphate, as well as to the maintenance of a sufficiently high level of protein synthesis under these conditions.

[The effect of guanosinetetraphosphate on rRNA synthesis in E. coli extracts]. / Vliianie guanozintetrafosfata na sintez rRNK v ekstraktakh kletok E. coli.

The synthesis of rRNA in the ribosome-free extracts S100 of E. coli cells was about 30 and 60% of total transcript when E. coli DNA and DNA of lambda rifd 18 phage were used respectively. The synthesis of rRNA with both types of DNA was inhibited in 5--6 times by 0.8 mM ppGpp, while the synthesis of total RNA decreased only two-fold. Selective action of ppGpp on rRNA synthesis is due to the intensive inhibition of the initiation of transcription of the appropriate genes. The rRNA synthesis and the inhibitory capacity of ppGpp was shown to dependend on the KCl concentration in S 100 extracts. These results indicate that ppGpp is the main factor controlling rRNA synthesis both in isolated RNA polymerase system and in cell-free extracts.

[Alpha-L-fucosidase activity in human blood]. / Al'fa - L-Fukozidaznaia aktivnost' cheloveka.

The alpha-L-fucosidase activity was studied in blood plasma and cells. In leucocytes and blood plasma of healthy persons the fucosidase activity varied considerably. The fucosidase activity in blood was not altered under pathological conditions other than fucosidosis. The fucosidase activity did not depend on sex and age of the persons studied. No correlation was observed between the values of the fucosidase activity. Two forms of fucosidase (alpha-L-fucosidase I and alpha-L-fucosidase II) were found in human leucocytes and blood plasma. Isoelectric focusing experiments indicates multiple forms alpha-L-fucosidase from human serum. The possibility is discussed of the use of human blood plasma and cells not only for estimation of the total fucosidase activity but also for studies of different forms of the enzyme.