Biomedical subjects

O B Chernova

Publications and source records attributed to O B Chernova.

22 records · Page 2Linked to original sources

PubMed1985

Gene amplification in Djungarian hamster cell lines possessing decreased plasma membrane permeability for colchicine and some other drugs.

By multistep selection a set of clones and sublines possessing different levels of resistance to colchicine or adriablastin was obtained from the SV40-transformed Djungarian hamster cell lines, DM-15 and DMcap. Resistance to both colchicine and adriablastin is associated with an alteration of plasma membrane permeability leading to a decreased uptake of various drugs (3H-colchicine, 3H-cytochalasin B, 3H-actinomycin D, 3H-puromycin, 3H-vinblastine, 14C-chloramphenicol). The DNA of cells highly resistant to cholchicine can transmit resistance only to low dosages of the drug. Comparison of DNAs from wild-type and resistant cells digested by restriction endonucleases revealed new classes of repeated DNA sequences in resistant cell lines. The degree of DNA repetition was correlated with the level of drug resistance. The repeated DNA sequences evidently represent parts of the genome that are amplified in resistant cells. The size of the amplified sequences is 200-250 kilobase pairs (kb). Cell lines highly resistant to colchicine contain amplified DNA, which like mitochondrial DNA replicate asynchronously with the main portion of the cellular DNA and related but not identical DNA sequences are amplified in independent cell lines selected for resistance to colchicine, adriablastin, and actinomycin D. These cell lines display similar patterns of alterations of plasma membrane permeability. The amplified DNA sequences may contain a gene or genes the overexpression of which leads to change in plasma membrane permeability and a development of resistance to various drugs.

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PubMed1981

[Characteristics of A-type intracytoplasmic particles produced by human cells].

Radioimmunoprecipitation was used to analyse comparatively proteins in cytoplasmic A-type particles (CAP) and structural proteins of D-type virions in Hep-2 system of cultivated human cells. Proteins of CAP were iodinated and studied by electrophoresis in SDS-PAAG. In the preparations obtained, 60 000 (p60), 45 000, 42 000 and 20 000 dalton proteins wee detected. p60 was the main protein in CAP. It was precipitated by purified CAP antiserum rather than by antisera against structural proteins of D-type virions. It was thus demonstrated that the main structural protein of CAP Hep-2 cells contains no antigenic determinants of structural proteins of D-type oncoviruses.

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PubMedDate not supplied

[Isolation of DNA probes for the detection of sequences amplified in colchicine-resistant cells].

Earlier we have found that the development of resistance to colchicine in mammalian cells in vitro is due to gene amplification leading to decreased plasma membrane permeability to the selective agent and some other unrelated drugs. By a stepwise self-renaturation procedure followed by chromatography on hydroxyapatite we isolated the fraction of middle-repeated sequences (DNAc0t = 10-250) enriched in amplified DNA from the DNA of colchicine-resistant Djungarian hamster cell line. Blotting-hybridization with [32P]DNAc0t = 10-250 performed in the presence of the excess of unlabelled DNA from wild type cells reveals amplified sequences in resistant cell lines. The comparison of DNAs from cell lines resistant to colchicine, adriablastin and actinomycin D showed that common but not identical DNA sequences are amplified in these cases. In situ hybridization with [3H]DNAc0t = 10-250 indicates that amplified sequences are located in the long homogeneously staining regions (HSRs) of the marker chromosomes. These results suggest that DNAc0t = 10-250 may be used for screening of recombinant molecules containing amplified sequences.

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PubMedDate not supplied

[Hormone-dependent process of the maturation of the major structural proteins of the mouse mammary tumor virus].

The following findings were obtained by the radio-immunoprecipitation method with antisera to gp52 and p27. When the cells were cultivated in a hormone-free medium, they contained precursors of proteins of gene gag (Pr 73gag) and gene evn (gPr 70env). No mature structural MTV proteins were found. The addition of insulin to the growth medium had no effect on maturation of protein precursors. When dexamethazone was added to the medium, gPr 70env "maturated" to gp52 of the main envelope glycoprotein of virion coat whereas Pr 73gag was not cleaved into final products. When the cells were cultivated in the presence of insulin and dexamethazone, there was a marked stimulation of Pr 73gag (although its maturation did not occur), g Pr 70env, and, especially, gp 52. Extracellular particles were found to contain p27 which was precipitated by homologous monospecific antiserum, that is, in the system of clone F2 cells processing of Pr 73gag occurred mainly in extracellular particles. Thus, expression of all three known genes (gag, pol, and env) occurred in the cells of cloned F2 culture.

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