DNA is made (green diagonals) during the reductive phase before respiration begins.
Klevecz/NAS
Damaging oxidizing agents are produced by respiration. In yeast, respiration is periodic—it alternates in ∼40-min cycles with a stage of nonrespiration called the reductive phase. This oscillation was detected decades ago, but it was never thought to be connected to cell cycle progression. Now, Klevecz shows that both S-phase entry and transcription are controlled by the respiratory oscillation.
Microarray analysis revealed that nearly 90% of transcribed yeast genes were maximally transcribed in two peaks during the reductive phase—one early and one late. The transcription of fewer than 700 genes, in contrast, peaked during respiration.
The respiration cycle also gated entry...
