Sephadex G-200 column chromatography of hepatoma DNA polymerase yields two peaks of enzyme activity. Peak I contains enzyme having a marked preference for denatured DNA, and the levels of this enzyme increase in proportion to tumor growth rate. Peak II contains the enzyme fraction having a moderate preference for native DNA. Normal and regenerating rat liver have a predominance of Peak II, in c...

We have developed a new strain of rats (resistant rat) which exhibit resistance against the carcinogenic action of several carcinogenic compounds. In the present study, we compared the ability of resistant rat liver to activate 3'-methyl-4-dimethylaminoazobenzene and 2-acetylaminofluorene to highly reactive metabolites, which can covalently bind to DNA, with that of carcinogen-sensitive parent ...

The major DNA adduct formed from the carcinogen ethylene dibromide (1,2-dibromoethane, EDB) is S-[2-(N7-guanyl)ethyl]glutathione, resulting from the reaction of guanyl residues with the half-mustard S-(2-bromoethyl)glutathione, which is generated by glutathione S-transferase-catalyzed conjugation of EDB with glutathione. The half-life of the alkylating species [putative S-(2-bromoethyl)glutathi...

OBJECTIVES Several reports demonstrated that ethanol administration impairs the DNA synthesis in rat hepatocytes. Also, it has been demonstrated that prostaglandin (PG) helps prevent membrane damage by hepatotoxic chemicals. In this study, the authors examined PG's effects on the toxicity of ethanol in the primary culture of rat regenerations. METHODS We examined two kinds of parameters, i.e....

This study demonstrates the ability of tar isolated from environmental tobacco smoke (ETS) to nick DNA in mammalian cells. Solutions of ETS tar behave similarly to aqueous solutions of cigarette tar from mainstream smoke. Both solutions contain the tar semiquinone radical, and this radical associates with the DNA in viable rat alveolar macrophages. Solutions of tar from ETS cause single-strand ...

Although Pst I does not cut the circular mitochondrial genome of the rat, BamHI generates from this genome two unequal fragments of DNA. Each of these fragments was cloned in pBR322. Nuclear DNA was digested from rat liver singly or doubly with Pst I and BamHI, and it was demonstrated that nuclear DNA shared a common sequence with the larger mitochondrial DNA BamHI fragment. The cloned larger m...

Chronic administration of acrylonitrile results in a dose-related increase in astrocytomas in rat brain, but the mechanism of acrylonitrile carcinogenicity is not fully understood. The potential of acrylonitrile or its metabolites to induce direct DNA damage as a mechanism for acrylonitrile carcinogenicity has been questioned, and recent studies indicate that the mechanism involves the inductio...

This investigation concerns with the effect of low intensity microwave (2.45 and 16.5 GHz, SAR. 1.0 and 2.01 W/kg respectively) radiation on developing rat brain. Wistar rats were exposed for 35 days at the above mentioned frequencies separately in two different exposure systems. After the exposure period the rats were sacrificed and the whole brain tissue was dissected and used for study of si...

The incorporation of tritiated thymidine into DNA molecules was studied by electr.:m microscopic autoradiography. To make autoradiogram in electron microscopic level, DNA was extracted from rat ascites hepatoma (AH 130) cells after in vitro incubation with tritiated thymidine. Extracted DNA samples were rotary shadowed with platinum palladium and covered with emulsion. Silver grains demonstrate...

The polyomavirus large T antigen promotes homologous recombination at high rates when expressed in rat cells carrying the viral replication origin and two repeats of viral DNA sequences stably integrated into the cellular genome. Recombination consists of both reciprocal and nonreciprocal events and is promoted by mutants defective in the initiation of viral DNA synthesis (L. St-Onge, L. Boucha...