On the increased precursor incorporation into the DNA of rat liver mitochondria irradiated in vitro.

The kinetics of incorporation of labelled precursors into the DNA of isolated rat liver mitochondria has been studied after X-irradiation in vitro. Incorporation ofH-TTP was slightly inhibited during the initial period, followed by an increase of about 25 % of the specific activity. Incorporations ofH-TdR andH-BUdR were also stimulated by irradiation of mitochondria, although the amount of incorporated precursor was lower than that ofH-TTP. This radiation-induced incorporation of precursors was abolished by the addition of ethidium bromide or EDTA. Degradation of mt-DNA, indicated by the decrease of specific radioactivity, was observed after irradiation of pre-labelled mitochondria; in presence of EDTA the degradation was not detected. These results were discussed from the viewpoint of the repair synthesis of mitochondrial DNA. [ABSTRACT FROM AUTHOR]