Circadian rhythms: Redox redux

Abstract

Oscillations in gene transcription that occur in response to biological daily clocks coordinate the physiological workings of living organism. But turnover in cellular energy may be sufficient to make a clock tick.

Figure 1. Coupling of genetic and metabolic clocks

Two types of circadian oscillator maintain synchrony between the light–dark environment and internal biochemical processes. These are genetic oscillators, which consist of a transcription–translation feedback loop, and — as two new studies^, show — metabolic oscillators, which are involved in fuel-utilization cycles and consist of the cycle of oxidation and reduction of peroxiredoxin enzymes. The two oscillator types are coupled, both driving rhythmic outputs (such as photosynthesis reaction cycles in plants and the feeding–fasting cycle in animals) in synchrony with Earth’s rotation.