Biomedical subjects

O Ilinskaya

Publications and source records attributed to O Ilinskaya.

3 recordsLinked to original sources

PubMed2001

Bacillus intermedius ribonuclease as inhibitor of cell proliferation and membrane current.

The antiproliferative action of the guanine-specific ribonuclease secreted by Bacillus intermedius (binase) was studied in different chicken and mouse cell lines. The proliferation rate of chicken embryo fibroblasts, either normal or Rous sarcoma virus-transformed, was significantly reduced by binase treatment. Among mouse fibroblasts, v-ras-transformed NIH3T3 cells were sensitive to binase, whereas the growth of non-transformed, v-src-transformed or v-fms-transformed NIH3T3 cells was not affected. A 48 h treatment with binase inhibited the Ca2+-dependent K+ current of v-ras-transformed NIH3T3 cells but had no effect on this membrane current in non-transformed and in v-src- or v-fms-transformed NIH3T3 cells. Our results suggest that mammalian cells expressing the ras-oncogene are a potential target for the antiproliferative action of binase.

3T3 Cells↗

PubMed1999

Discrimination between genotoxicity and cytotoxicity for the induction of DNA double-strand breaks in cells treated with aldehydes and diepoxides.

The time-dependent dose-response relationships for the induction of DNA double-strand breaks (DSB) assessed by pulsed-field gel electrophoresis (PFGE) and for viability (evaluated by the MTT cytotoxicity test) were investigated in order to discriminate between genotoxic and cytotoxic mechanisms of DNA fragmentation. Cultured human lung epithelial cells (A549) were treated (i) with the aldehydes formaldehyde or glutaraldehyde and (ii) with the DNA-DNA interstrand crosslinkers melphalan, diepoxybutane or diepoxyoctane. Induction of DSB by formaldehyde and glutaraldehyde was seen only after cell viability was reduced to less than about 60% of the control values, indicating that DSB were the consequence of extragenomic damage and viability loss. Melphalan, diepoxybutane and diepoxyoctane induced DSB by a genotoxic mode with concentrations that did not affect cell survival: 8 h after treatment initiation both heat-labile crosslinks and DSB could be detected. Cells were not able to repair the crosslinks induced by diepoxybutane, the crosslinker with the shortest chain length. In contrast, with melphalan and diepoxyoctane, which have a longer crosslinking property considerable repair of crosslinks was observed. The molecular size distribution of the produced DNA fragments supported this mechanistic distinction. The DNA fragments generated by diepoxides were initially large, their concentration decreasing monotonously from 7 Mbp to less than 1 Mbp and were converted to smaller fragments by 72 h in the course of cell death. In contrast, DNA fragments induced by formaldehyde peaked below 1 Mbp, implicating activation of DNA-degrading enzymes.

Aldehydes↗

PubMed1995

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↗