Clocks James Qualtrough from Flickr
We believe that as organisms had to buffer against rhythmic free radicals, they developed 24 hour oscillations in the peroxiredoxin proteins to protect themselves at appropriate times of the day. These cycles appear to have become so important that they became autonomous."
—Dr Akhilesh Reddy, from the Institute of Metabolic Science at the University of Cambridge
A metabolic protein involved in circadian rhythms has been found in all three domains of cellular life (bacteria, archaea and eukaryote), new research reveals.
The discovery dispels the previously held belief that, because no shared clock mechanisms had been identified, circadian rhythms had evolved independently in different organisms. The new research suggests that circadian clocks may share a common ancestor.
Circadian rhythms, which regulate the cycles of everything from metabolism to behaviour, operate on a 24-hour clock. The scientists hypothesise that these clocks evolved over 2.5 billion years ago. At the time, the levels of oxygen in the atmosphere were increasing. Some organisms perished, but other organisms with the peroxiredoxin proteins, which act to minimise the damage caused by naturally generated toxic free radicals, were able to survive.
Lead author Akhilesh Reddy, from the Institute of Metabolic Science at the University of Cambridge, said: "We believe that as organisms had to buffer against rhythmic free radicals, they developed 24 hour oscillations in the peroxiredoxin proteins to protect themselves at appropriate times of the day. These cycles appear to have become so important that they became autonomous."
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