Résumé
Mitochondrial transcription has been studied as a function of mitochondriogenesis in yeast cells. Two systems have been used: synchronously growing cells and cells subjected to glucose repression followed by derepression. Maximal RNA synthesis has been found in the S phase of the cell cycle and during the 'repressed' phase in asynchronous cells. Activities of RNA polymerase, poly A polymerase and incorporation of [32P]-into RNA in vitro are maximal at the same period. Gel analysis reveals the presence of some high molecular weight RNA species which are likely to be precursors. When chase experiments are carried out in the presence of excess glucose, the high molecular weight species remain unaffected, suggesting that RNA processing may be an important site of action of glucose repression.