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R R Azizbekian

Publications and source records attributed to R R Azizbekian.

At least 19 recordsLinked to original sources
PubMed1992

[Site-specific restrictases from Bacillus thuringiensis var. Kumantoensis].

The efficiency of bacteriophages CP-54 and CP-55 plating on Bacillus thuringiensis var. kumantoensis H18 (Kum) is decreased about 10-fold as compared with the efficiency of plating on Bacillus thuringiensis var. galleriae H5 (Gal). Bacteriophages having propagated for one cycle in Kum cells might be further grown in this strain without growth restriction. Two site-specific restriction enzymes isolated from Bacillus thuringiensis var. kumantoensis were designated BtkI and BtkII. The endonuclease BtkI recognises the same nucleotide sequence CGCG in DNA as recognised by the restriction endonuclease FnuDII; BtkII recognises the same nucleotide sequence GATC as the endonuclease Sau3A.

Bacillus thuringiensis↗
PubMed1990

[Conjugation transfer of the pAMbeta1 plasmid to Bacillus anthracis].

The possibility of conjugational transfer of the plasmid pAM beta 1 in the cells of different strains of Bacillus anthracis has been established. The efficiency of the plasmid replicon transfer in interspecies transfer B. thuringiensis X B. anthracis was n.10(-7), while in interspecies transfer it was n.10(-6). The capability of mobilization of extrachromosomal replicon pTG141 for conjugational transfer has been demonstrated. Bacillus anthracis transconjugants harbouring the pAM beta 1 plasmid have acquired the donor properties in conjugation.

Bacillus anthracis↗
PubMed1989

[Plasmid transduction by Bacillus anthracis bacteriophage CP54].

Possibility of plasmid transduction in Bacillus anthracis vaccine strains Sterne and STI-1 by bacteriophage CP54ant having an increased ability of adsorbtion and a shortened period of latent development in Bacillus anthracis cells has been isolated. The main parameters of plasmid transduction by the bacteriophage have been established for the plasmid pTG141 (TcR). They include the effect of multiplicity of infection, the level of UV-inactivation of bacteriophage, the presence of antiphage serum in the incubation medium. Plasmid transduction by the mutant phage CP54ant was found to be more efficient as compared with the one by the parent phage. The isolated transductants served as donors of the transduced plasmid for Bacillus anthracis and Bacillus thuringiensis strains.

Bacillus anthracis↗
PubMed1989

[Site-specific restriction endonuclease BtcI from Bacillus thuringiensis var. canadensis].

Efficiency of bacteriophage Tp4 plating on Bacillus thuringiensis var. canadensis H5 (Can) is decreased 10(7)-fold as compared with the efficiency of plating on Bacillus thuringiensis var. galleriae H5 (Gal). Bacteriophage Tp4 having propagated for one cycle in Can cells might be further grown in this strain without restriction. The sitespecific restriction endonuclease BtcI isolated from Bacillus thuringiensis var. canadensis recognises the same nucleotide sequence GATC in DNA as recognised by restriction endonuclease Sau3A.

Bacillus thuringiensis↗
PubMed1987

[Homologous and heterologous transcription of the Cry+-plasmid in Bacillus thuringiensis].

The possibility of homologous and heterologous transception of Cry+ plasmids in Bacillus thuringiensis is demonstrated. Cry+ plasmids from crystal bearing strain of Bacillus thuringiensis were transferred into acrystalline strain belonging to H5 serotype by mutual incubation. The donor strain was previously marked by the transmissive plasmid pAM beta 1 coding for erythromycin and lincomycin resistance. The transcipients having acquired the ability to synthesize delta-endotoxin were referred to H5 serotype due to their phenotype. By analogous method Cry+ plasmid was transferred from Bacillus thuringiensis to Bacillus cereus. Bacillus cereus strain GP7 was used as a recipient strain resistant to tetracycline. The presence of delta-endotoxin in transcipients was confirmed by bioprobes and immunoenzyme assay. To prove the transfer of Cry+ plasmid the plasmid profiles of the parent strains and transcipients have been analyzed. The formation of cellular contacts during mutual incubation of Bacillus thuringiensis and Bacillus cereus strains was demonstrated by electron microscopic study of ultrafine cuts.

Bacillus thuringiensis↗
PubMed1987

[The role of plasmids in the regulation of delta-endotoxin synthesis in Bacillus thuringiensis H14].

The role of plasmids in regulation of delta-endotoxin synthesis by Bacillus thuringiensis H14 was studied. The derivatives of strain Is-1 H14 containing a 4Md plasmid integrated into the chromosome synthesize small crystals and are not toxic for the gnat larvae. The transceptional transfer into this strain of a plasmid coding for crystal synthesis from the strain 69-6 serotype H5 results in restoration of insecticidal activity to the level of the parental strain Is-1. Transcipients activity is increased 10-15 fold in case of 4Md plasmid excision from the chromosome and autonomous functioning. Evidently, 4Md plasmid from the strain Is-1 as well as a plasmid coding for crystal synthesis from the strain 69-6 contains the regulatory elements participating in the expression of crystalline protein genes localized on other plasmids. The existence of two cellular regulatory groups is supposed to result in the significant increase in crystalline protein synthesis.

Bacillus thuringiensis↗
PubMed1985

[Effect of the pC194 plasmid on the development of Bacillus thuringiensis phages].

Bacillus thuringiensis var. galleriae strains were transformed by plasmid pC194, coding for chloramphenicol resistance (CmR). Efficiency of plating and the yields of bacteriophages Tg13 and Tg27 maturating in CmR transformant cells were decreased for 2-3 orders as compared with the ones in parental strains. The CmR transformants are characterized by the increased level of spontaneous induction of bacteriophage Tg22.

Bacillus thuringiensis↗
PubMed1985

[Characteristics of Bacillus thuringiensis phages with circular permutation in the DNA molecule].

Bacteriophages Tm2 and Tg27 of different origins but identical in biological properties have been compared. Physicochemical characteristics of bacteriophages have revealed the existence of end repeats and circular permutation of phage DNA. Phages Tm2 and Tg27 share the same dimensions of incapsulated DNA, differing in the sizes of phage genome and end repeats. Bacteriophage Tm2 genome is 45.2 kb. long with the end repeats containing 5.7%. The genome of Tg27 is 42.53 kb and 11.8% of end repeat. The bacteriophages relation has been confirmed by heteroduplex and restriction analysis. Tm2 and Tg27 share 84% of homology. Two regions of nonhomology are found representing a single-stranded loop and equishouldered vesicle with the sizes 2.19 kb and 5.03 kb, respectively.

Bacillus thuringiensis↗
PubMed1984

[Intervariant transduction in Bacillus thuringiensis].

This report deals with intervariant transduction in strains of Bacillus thuringiensis subsp, dendrolimus and galleriae with bacteriophage Tg13. This bacteriophage has a broad host range and is of a large DNA molecular mass (40.3 mD). Transducing properties of this bacteriophage were studied in Bacillus thuringiensis var. galleriae using auxotrophic mutants requiring purine and pyrimidine bases or tryptophan as recipients. The frequency of transduction was 10(-5)-10(-6). In order to prove the possibility of intervariant transduction, two series of experiments have been conducted. In the first case, bacteriophage tg13 has been propagated on the prototrophic strain 49-18 (var. dendrolimus), 48gua (var. galleriae) being used as a recipient. In the second case, the prototrophic strain 69-6 (var. galleriae) served as a donor and 49-18-1 trp (var. dendrolimus) - as a recipient. The frequency of heterologous transduction was 10(-7). The positive result obtained in cross-transduction experiments may be explained by common metabolic pathways of purine and pyrimidine bases and amino acids in strains of different serotypes.

Bacillus thuringiensis↗
PubMed1983

[Simultaneous reversion for genes thy, dra and drm in Bacillus thuringiensis].

The reversions of mutations in genes thy, dra (deoxyriboaldolase) and drm (phosphodeoxyribomutase) were studied in Bacillus thuringiensis var. galleriae 351. In this strain, both dra and drm mutants are sensitive to the presence of thymidine (Tds). In addition to the reversions for one of the properties (thymine requirement or sensitivity to thymidine), the simultaneous reversions for both properties (Thy + Tdr) were indicated. The frequency of Thy + Tdr revertants varied from 10(-4) to 10(-8), depending on both a selection method and the conditions of preliminary cultivation. The Thy + Tdr revertants had a rough (R) colony morphology in 100% of the cases, though the parental strains were of smooth (S) colony morphology. Selection for R variants, visually or by means of screening for Tg4 resistant or tetracycline resistant clones, resulted in detecting double Thy + Tdr revertants in 100% of the cases. The parental Thy - Tds phenotype restored after R leads to S conversion which occurred at the frequency 10(-7) to 10(-8) and might be detected by means of streptomycine selection.

Aldehyde-Lyases↗
PubMed1983

[Interspecific recombinants of Bacillus thuringiensis x Bacillus cereus].

The possibility of interspecies recombination was shown by using protoplast fusion method. The Bacillus thuringiensis var. galleriae strain 48S Thi Nic Gua Rifr Strr and 56R Gua Rifr, and also Bac. cereus carrying the plasmid pBC16 responsible for resistance to tetracycline (150 mcg/ml) were used. Recombinants were selected on the medium containing rifampicin and tetracycline. They were shown to combine the properties of both parents. The majority of recombinants were resistant to phages Tg4 and Td15 and represented the mean level of sensitivity to phages Tg12, Tg13 and Td14. Examination of the plasmid profiles of recombinants revealed that their resistance to tetracycline was due to the plasmid with mobility analogous to pBC16. It was concluded that the protoplast fusion method can be used to obtain recombinants between relatively remote species of microorganisms.

Bacillus cereus↗
PubMed1981

[Instability of the auxotrophic markers in Bacillus thuringiensis].

Auxotrophic mutants of Bacillus thuringiensis have been isolated and compared with the mutants of Bacillus subtilis. It has been found that after spore formation and a prolonged storage, the considerable part of cells in a population of some strains display a genetically unstable additional requirement for arginine with high frequency. The correlation between tetracycline sensitivity and unstable requirement for arginine and other growth factors has been found. The possible reasons for instability of genetic markers in Bac. thuringiensis are discussed.

Arginine↗
PubMed1981

[Extracellular serine proteinase of Bacillus thuringiensis].

Pure extracellular serine proteinase has been isolated from a broth filtrate of Bacillus thuringiensis, strain 69-6R by fractionation with ammonium sulfate and affinity chromatography on Sepharose 4B derivatives containing p-(omega-aminomethyl)-phenylboronic acid and cyclopeptide bacillichin as ligands. The enzyme is completely inactivated by phenylmethylsolfonyl fluoride, a specific reagent for serine proteinases, has the molecular weight of 29 000 and pI of 8.4, reveals maximal activity and stability at pH 8.5 and is inactivated at pH values below 4 and above 10 and at temperatures above 60 degrees. The enzyme hydrolyzed azokasein, bovine serum albumin and synthetic chromogenic peptide substrates, e.g. benzyloxycarbonyl-L-alanyl-L-alanyl-L-leucyl p-nitroanilide and possesses the esterolytic activity. In terms of its physico-chemical characteristics, interaction with specific inhibitors and substrates, extracellular serine proteinase from Bacillus thuringiensis can be related to subtilisins. However, its amino acid composition-Lys16, His4, Arg8, Asx28, Thr16, Ser18, Glx29, Pro12, Gly32, Ala31, Val19, Met5, Ile12, Leu18, Tyr11, Phe10, Trp4 appears to be an intermediate between that of subtilisins and intracellular serine proteinases of Bacilli.

Amino Acids↗
PubMed1981

[Bacillus thuringiensis bacteriophage interference].

Strains of Bacillus thuringiensis lysogenic for temperate bacteriophage Tm2 inhibit the development of virulent bacteriophage Tg4, although the latter can absorb to and kill these bacteria. Tm2 mediated interference did not act directly on the Tg4 genome; rather, the phage altered the host physiology. The latent period of Tg4 growth in Bac. thuringiensis lysogenic for phage Tm2 was longer than when nonlysogenic bacteria were infected. Progeny yields have been counted in Bac. thuringiensis strain mixedly infected with two unrelated phages-Tg4 and Tm2 in a varying order of addition. The dominance was dependent on the order of addition. Under the conditions of mixed infections, only single phage (Tm2 or Tg4) produced a significant number of progeny, provided, it was added 5 min before the infection with the other phage. When two phages were added simultaneously, the yields of both phages were reduced.

Bacillus thuringiensis↗