ABSTRACT
Employing the CHO/HGPRT system, we have shown that the acetone fraction of a crude coal--liquid crude oil is the major contributor to the mutagenicity of synthetic oil. The system appears to be useful for determination of mutagenicity of organic mixtures and for corroboration of results from other biological assays.
Subject(s)
Coal , Fuel Oils , Mutagens , Petroleum , Animals , Cell Line , Cricetinae , Cricetulus , Drug Evaluation, Preclinical , Female , Genetic Techniques , Hypoxanthine Phosphoribosyltransferase/genetics , OvarySubject(s)
Alkylating Agents/toxicity , Carcinogens , Mutagens , Toxicology/methods , Animals , Cell Survival/drug effects , Cell Survival/radiation effects , Cells, Cultured , Cricetinae , Dose-Response Relationship, Drug , Mesylates/toxicity , Mutation/radiation effects , Nitrogen Mustard Compounds/toxicity , Nitrosamines/toxicity , Ploidies , Structure-Activity Relationship , Sunlight , Technology, Radiologic , Ultraviolet Rays , X-RaysABSTRACT
Chicken-erythrocyte inner histone tetramer has been complexed with several natural and synthetic DNA duplexes by salt-gradient dialysis at various protein/DNA ratios. The resulting complexes, in low-ionic-strength buffer, have been examined by electron microscopy, circular dichroism, and thermal denaturation. Electron microscopy reveals nucleosomes (nu bodies) randomly arranged along DNA fibers, including poly(dA-dT)-poly(dA-dT), poly(dI-dC)-poly(dI-dC), but not poly(dA)-poly(dT). Circular dichroism studies showed prominent histone alpha-helix and "suppression" of nucleic acid ellipticity (lambda less than 240 nm). Thermal denaturation experiments revealed Tm behavior comparable to that of H1- (or H5-) depleted chromatin. Tm III and Tm IV increased linearly with G + C%(natural DNAs), but were virtually independent of the histone/DNA ratio; therefore, the melting of nucleosomes along a DNA chain is insensitive to adjacent "spacer" DNA lengths. This suggests that Tm III and Tm IV arise from the melting of different domains of DNA associated with the core nu body.
