INCREASE IN MACROMOLECULAR AMOUNTS DURING THE CELL-CYCLE OF TETRAHYMENA - CONTRIBUTION TO CELL-CYCLE CONTROL

  • 1 January 1979
    • journal article
    • research article
    • Vol. 37  (JUN) , 117-124
Abstract
Increase in RNA, protein and cell size was determined cytophotometrically during the cell division cycle of Tetrahymena. For these parameters different patterns were found. RNA accumulates slowly during G1 period and faster during macronuclear S. This agrees with the changing uridine-incorporation rate which is at least partly related to the varying macronuclear DNA amount. Increase in protein content and cell size occur mainly during G1 and G2. This pattern was confirmed by determining the RNA:protein ratio in individual cells. It is minimal at the end of the G1 period. Initiation of DNA replication seems to be under negative control by the relative RNA content of the cell.