[Detection of free histidine by thin-layer chromatography].
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Chromatography, Thin Layer↗
Biomedical subjects
O B Ivanchenko
Publications and source records attributed to O B Ivanchenko.
[Genotoxic effects of metabolic derivatives of the new drug phosphabenzide].
Genotoxic action of four possible metabolites of the new tranquilizer phosphabenzide (acetylphosphabenzide, diphenylphosphinylacetic acid, phosphabenzide hydrazone with pyruvic acid, bis-1,2-(diphenylphosphinylacetyl)hydrazine) has been studied. These metabolites belong to slightly toxic phosphororganic compounds. The Ames Salmonella/microsomes tests performed on strains TA100 and TA98 showed that of these compounds only acetylphosphabenzide possessed mutagenic action. Metabolic activation of liver microsomes decreased the mutagenic effect. The mechanism of action of acetylphosphabenzide is likely to involve the formation of acetylhydrazine, capable of producing active electrophiles attacking DNA.
Biotransformation↗
[Genotoxic effects of tonarol].
Genotoxic effects of 2,6-di-tret-butyl-4-methylphenol (tonarol) were studied using four test systems: the Ames test, the SOS chromotest, the cytogenetic test with rootlets of onion (Allium cepa), and the in vivo micronucleus test. Tonarol did not affect gene mutation induction in Salmonella typhimurium tester strains, the SOS response in the Escherichia coli strain PQ37, chromosomal aberrations in cells of onion (Allium cepa) rootlets, and micronuclei in erythrocytes of peripheral blood of CBA x C5713 L/G mice. Tonarol induced cell division in A.
Allium↗
SOS-inducing ability of native and mutant microbial ribonucleases.
The results of genotoxicity testing of microbial ribonucleases from Bacillus species with different catalytic activity obtained by site-directed mutagenesis in SOS chromotest are reported. At the concentrations 0.1-1 mg/ml, the induction factor for wild-type bacillar binase, barnase and mutant Arg58Lys binase with 100% activity was found to be significantly higher than 1.5 (1.8-2.8). Mutant RNases having decreased catalytic activity (binases with replacements Lys26Ala, Arg61Gln, His101Glu) or through natural inhibitor barstar inactivated wild-type RNase exhibited no SOS-inducing potency. The ability of native bacillar RNases and mutant enzymes possessing high catalytic activity comparable with the activity of wild-type RNase to cause the SOS response indicates that genotoxicity is mediated through the probable cleavage of cellular RNA.
Bacterial Proteins↗
Bacterial ribonuclease: mutagenic effect in microbial test-systems.
Pure enzyme samples of ribonuclease from Bacillus intermedius 7P (known commercially as 'binase') were investigated for genotoxicity in four microbial tests: the Ames plate incorporation method, AraR-assay; the prophage induction test; and the DNA-repair test. The weak mutagenic effect of binase at high concentrations (0.1 mg/plate, 1 mg/plate) was established by induction of forward AraR-mutations and histidine-reverse mutations (both frameshift mutations and base pair substitution). Metabolic activation with rat or chicken liver, human placenta or plant (from tulip bulbs) microsomal fractions in vitro was seen to abolish the binase mutagenicity. Bacillus intermedius 7P ribonuclease appears to possess DNA damaging activity in uvrA- and polA- mutants, but not in the recA-deficient Escherichia coli strain, and exhibits an induction of recA-dependent mutagenesis detected by the 8-fold increase of the prophage-induction level in lysogenic Bacillus subtilis culture and by the 5-fold increase of this level in the Streptomyces lavendulae 3 lysogenic strain. The importance of the roles of both of enzyme catalytic activity and native structure is emphasized. A proposed mechanism for exogenous ribonuclease action is discussed. Bacillus intermedius 7P ribonuclease probably does not act as a direct genotoxic agent interacting with DNA, but could provoke nucleotide imbalance through its catalytic action on membrane-associated RNAs, which results in alteration of DNA replication and, as a consequence, in recA-dependent mutagenesis.
Arabinose↗
[2,4,6-trinitrotoluene and 2,4-diamino-6-nitrotoluene: the absence of recA-dependent mutagenesis?].
The genotoxicity of 2,4,6-trinitrotoluene (2,4,6-TNT) and its amino derivative, 2,4-diamino-6-nitrotoluene (2,4-DA-6-NT), was studied using the Escherichia coli tester strain PQ37 in the SOS chromotest. The compound 2,4,6-TNT, without metabolic activation, virtually failed to induce an SOS effect in cells of the tester bacteria. Consequently, mutagenic activity of 2,4,6-TNT, which was shown earlier in the Ames test, does not depend on SOS mutagenesis. It was demonstrated that metabolic activation with the microsomal S9 human placenta fraction results in a threefold increase in the induction factor of the SOS effect caused by 2,4,6-TNT. The absence of the SOS-inducing activity of 2,4-DA-6-NT, regardless of the presence of a microsomal activating mixture, is shown. Thus, 2,4-DA-6-NT does not belong to metabolites of 2,4,6-TNT, responsible for the genotoxicity of this compound.
Biotransformation↗
[Mutagenic activity of 2,4,6-trinitrotoluene: the role of metabolizing enzymes].
Mutagenic activity of 2,4,6-trinitrotoluene (2,4,6-TNT) and one of its derivatives, 2,4-diamino-6-nitrotoluene (2,4-DA-6-NT) was studied in the Ames test using the Salmonella typhimurium tester strains TA98, TA100, TA100NR (deficient in classical nitroreductases), and TA100/1, 8DNP (deficient in O-acetyltransferase). The number of revertants was significantly increased by 2,4,6-TNT, in comparison with that of spontaneous revertants. Base pair substitutions were preferentially induced by 2,4,6-TNT. The mutagenic effect of this compound was virtually altered by in vitro metabolic activation with the S9 fraction of human placenta. Neither 2,4,6-TNT nor 2,4-DA-6-NT exhibited mutagenic activity in the strains TA 100NR and TA 100/1,8DNP. Based on the results obtained, it is concluded that the mutagenic potential of 2,4,6-TNT is determined by its metabolites that form during bacterial metabolism. Bacterial nitroreductases and O-acetyltransferases are the key activators of this compound to form the ultimate mutagens.
Biotransformation↗
[An evaluation of the genotoxicity of nonionogenic surface-active substances].
The mutagenic activity of 16 industrial nonionic surfactant samples has been investigated in Ames-test without metabolic activation and with the use of mouse liver microsomal fraction in vitro. The genotoxical estimation of their possible biodegradation products is given. The mutagenicity of a number of high molecular polyethylene glycoles related to nonionic surfactants is shown.
Biodegradation, Environmental↗
[The mechanisms of the manifestation of the genotoxic effects of binase].
The high concentrations of commercial sample of Bacillus intermedius 7P ribonuclease (binase) showed a weak mutagenic effect in Ames test and Ara-test. It has been established that binase induces the SOS-functions of microbial cell and prophage induction. The way of exogenic enzyme action through activation of RecA protein is proposed.
Bacillus↗
[Assessment of the genotoxicity of the "Binase" enzyme preparation].
"Binase" enzyme sample (a microbial ribonuclease) has been tested for mutagenicity in a set of tests. The set included Ames test Salmonella/microsome, Escherichia coli Rec-test, bacteriophage induction assay, DNA-repair synthesis in lymphoid cells. "Binase" is shown to possess a small genotoxic effect at high concentrations. Both animal and plant S-9 fractions eliminated the effect.
Animals↗
[Effect of thermal processing of Bacillus intermedius ribonuclease on its catalytic activity and biological properties].
Bacillus intermedius ribonuclease (binase), which is known to exert a growth-stimulating effect at low concentrations and a genotoxic effect at high concentrations, loses these abilities completely after exposure to 100 degrees C for 10 min, but retains approximately 96% of its catalytic activity and structural integrity. Other types of modification, such as photoinactivation and site-specific mutagenesis, gave rise to enzyme forms with unaltered structure but reduced (sometimes to trace amounts) catalytic activity. Genotoxicity was always proportional to the catalytic activity of the native enzyme, while a notable growth-stimulating effect may be exerted by enzymes with low activity. The loss of biological activity of thermoinactivated binase was related to the increase in the number of negatively charged groups on the enzyme surface, which led to a substantial decline in the adhesive properties of the enzyme.
Bacillus↗
[Genotoxicity of the preparation "binase" in tests on Salmonella: Ames test and ARA-test].
The present work deals with mutagenicity determination of enzyme sample "binase" (Bacillus intermedius ribonuclease) in microbial test-systems: Ames test and Ara-test. The weak mutagenic effect of "binase" high concentration was established in both tests by induction of forward Ara-mutations and Histidine-reverse mutations. A metabolic activation is seen to remove this effect.
Arabinose↗
[Antimutagenic activity of the enzyme preparation "binase" in microbial test systems].
The occurrence of microorganisms and the rates of terminal biogenic reduction of sulfates and synthesis of methane in stratal waters in deposit 302 of Bashkir Carboniferous deposition at the Romashkinskoe oil field were studied. It was shown that deposit 302 is a dynamic, highly reduced ecosystem containing sulfates and hydrogen sulfide in considerable concentrations, in which active biogenic processes occur. Sulfate reduction is a dominating anaerobic process by which the organic constituents of oil are transformed. The sulfate-reducing microflora is quite varied and characterized by high metabolic potentials. Enriched cultures, which can oxidize many organic substances, such as benzoate, acetate, ethanol, or lactate, at the expense of reduction of sulfates and ferric ion, were isolated from the samples extracted from deposit 302. It was suggested that the sulfate-reducing microflora might be responsible not only for sulfate reduction in the stratum but also for mobilization of part of insoluble iron oxides in the oil trap rock. The findings indicate that the dissimilation sulfate- and iron-reducing bacteria can contribute to the geochemistry of organic and mineral compounds in underground ecosystems.
Antimutagenic Agents↗
[Dependence of the intensity of 2,4,6-trinitrotoluene-induced mutagenesis on the physiological state of tester strains of Salmonella typhimurium].
The dependence of the mutagenic potential of 2,4,6-trinitrotoluene (TNT) on the growth phase of the Salmonella typhimurium tester strains TA100 and TA98 is shown. The mutagenic potential proved to be maximal for log-phase cultures, being higher with strain TA100 than TA98. The amount of TNT absorbed by bacteria in the first minutes of contact varied, depending on culture age, and was the largest at the beginning of the exponential growth phase. A direct relation between the number of microbial cells and the amount of TNT absorbed from the medium was shown. The analysis of infrared (IR) spectra of cells after a 3-min contact with TNT, demonstrated that, at physiological temperatures, 2.4% of the original amount of TNT was present in cells of the tester strain in an unaltered form, while, at a lowered temperature, this value was 10.3%. Thus, the retardation of physiological processes in the cell changes the intensity of mutagen absorption and transformation. It is emphasized that an accurate assessment of mutagenicity should take into account the physiological state of tester bacteria.
Absorption↗
[Induction of the SOS-response with Bacillus intermedius RNAase].
This paper deals with the induction of the SOS-functions of a bacterial cell by the exogenous ribonuclease of Bacillus intermedius. Two test systems were employed, which made it possible to quantitatively estimate SOS-response induction activity in gram-positive and gram-negative bacteria. It was established that the catalytically active enzyme elicits the SOS-response in the cells of Escherichia coli PQ 37 and causes prophage induction in the lysogenic strain Bacillus subtilis 168 phi 105 WT (a phenomenon related to the SOS-response). An enzyme with a His101Glu-substituted active center, exhibiting residual catalytic activity, failed to induce the SOS-response in an SOS-chromotest with E. coli PQ 37, indicating dependence of the SOS-inducing effect of the enzyme on its catalytic activity. It is suggested that the effect of active ribonuclease on membrane-bound and cytoplasmic RNA causes a change in the nucleotide pool and, as a consequence, elicits the SOS-response of the cell.
Bacillus↗