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Biomedical subjects

R A Zakharian

Publications and source records attributed to R A Zakharian.

5 recordsLinked to original sources
PubMed1978

[Studies of nucleic acid metabolism in cultured chick embryo cells infected with Mycoplasma gallisepticum].

M. gallisepticum infection of cultured chick embryo cells led to a sharp reduction the rate of 3H-thymidine and 3H-uridine incorporation into DNA and RNA cells, and almost completely suppressed the transposition of uridine label from the nucleus into the cytoplasm, this pointing to the inhibition of escape of RNA synthesized de novo into the infected cells cytoplasm. As suggested, weak labeling of the cytoplasm after prolonged (about several hours) incubation of cultured cells with labeled urine could indicate infection of cell cultures with the mycoplasmae.

Animals↗
PubMedDate not supplied

[Effect of dexamethasone and arecoline on the 5-methylcytosine and pyrimidine blocks in the DNA of certain sections of the brain, the liver and the spleen of rats].

In DNA of rat brain and liver tissues content of 5-methylcytosine increased by about 25 percent after dexamethasone administration; arecholine decreased content of 5-methylcytosine by about 20 percent. No other essential changes (GC content, amount of different pyrimidine isoplits) were found in these DNA. These data suggested that changes in 5-methylcytosine content in DNA studied were due to difference in DNA methylation rather than to alteration in DNA molecular population. The changes in DNA methylation, induced by the hormone or the alkaloid, were tissue-specific (brain, liver but not spleen). The level of DNA methylation was different in various parts of brain and correlated with the functional activity of the corresponding cells or genes. The alterations in DNA methylation, induced by the hormone or by the alkaloid, corresponded to changes in RNA synthesis. Thus, DNA methylation may be one of possible control mechanisms of transcription.

Animals↗
PubMedDate not supplied

[Bacillus thuringiensis plasmid DNA].

Plasmid DNAs were isolated from Bacillus thuringiensis and their physico-chemical properties were studied. The DNAs were purified using ultracentrifugation in a CsCl2 density gradient. The molecular weight of these extrachromosomal DNAs determined by electrophoresis in 0.6% agarose gel and by electron microscopy was 6 . 10(6)--10 . 10(6) daltons; a DNA with a molecular weight of 90 . 10(6) daltons was also found. Digestion with restriction endonuclease EcoRI yielded fragments of the plasmid DNAs with cohesive ends; these were further identified by means of electrophoresis in 1% agarose gel.

Bacillus thuringiensis↗
PubMedDate not supplied

[Characteristics of Pseudomonas putida plasmid DNAs].

Physico-chemical characteristics of plasmid DNAs isoalted from Pseudomonas putida G7 were studied as well as the behavior of these DNAs in th eourse of chromatography on columns with Sepharose 4B and kieselguhr with methylated albumin (MAC). This strain was found to contain several plasmid DNAs having molecular weights of 33-36X10(6), 15-18X10(6), and 3-5X10(6) dalton. The plasmid DNAs of biodegradation are supposed to be located in the vicinity of chromosomes, and only a small part of them is characterized by extrachromosomal localization.

Chemical Phenomena↗