[DNA polymerase gamma in the cells of loach embryos localized in mitochondria]

The homogenate of loach (Misgurnus fossilis) embryonic cells was fractionated by differential centrifugation into fractions, in which the activities of DNA polymerases alpha and gamma were measured. About half of the total alpha-polymerase activity was retained in the postmicrosomal supernatant. The activity of gamma-polymerase in the supernatant did not exceed 2% of the total activity. The specific activity of gamma-polymerase was maximal in the mitochondrial pellet. The enzyme activity in the nuclear pellet was proportional to the activity of mitochondrial enzymes, cytochrome oxidase and KCN-insensitive superoxide dismutase. The nuclei were separated from gamma-polymerase-containing fraction by ultracentrifugation in a 10-50% sucrose density gradient. The material of this fraction was identical to the mitochondria in terms of buoyant density, morphology and enzymatic properties. Thus, in loach embryos the fraction of gamma-polymerase associated with the nuclei is absent; the total gamma-polymerase activity is localized in the mitochondria.