Determination of some mitochondrial RNAs concentration in adult rat liver.

A method has been developed to accurately measure steady state concentrations of mitochondrial transcripts in adult rat liver. Total mitochondrial RNA has been hybridized with an excess of labelled mitochondrial DNA fragments coding for a single gene or a piece of it. The results obtained show that each mitochondrion contains 36 molecules of 16S rRNA, 81 of 12S rRNA and about 8 molecules of mRNAs coding for identified and unidentified reading frames. Thus, the rRNA/mRNA ratio in rat liver differs from that reported in HeLa cell mitochondria. These results are discussed in the light of mitochondrial DNA transcription regulation.