Mechanism that controls 24-hour clock of all forms of life discovered

LONDON - Scientists have discovered the mechanism that controls the internal 24-hour clock of all forms of life from human cells to algae.ot only does the research provide important insight into health-related problems linked to individuals with disrupted clocks - such as pilots and shift workers - it also indicates that the 24-hour circadian clock found in human cells is the same as that found in algae and dates back millions of years to early life on Earth.

Two new studies from the Universities of Cambridge and Edinburgh give insight into the circadian clock which controls patterns of daily and seasonal activity, from sleep cycles to butterfly migrations to flower opening.

One study, from the University of Cambridge’s Institute of Metabolic Science, has for the first time identified 24-hour rhythms in red blood cells. This is significant because circadian rhythms have always been assumed to be linked to DNA and gene activity, but - unlike most of the other cells in the body - red blood cells do not have DNA.

“We know that clocks exist in all our cells; they’re hard-wired into the cell. Imagine what we’d be like without a clock to guide us through our days. The cell would be in the same position if it didn’t have a clock to coordinate its daily activities,” Akhilesh Reddy, from the University of Cambridge and lead author of the study, said.

For the study, the scientists, funded by the Wellcome Trust, incubated purified red blood cells from healthy volunteers in the dark and at body temperature, and sampled them at regular intervals for several days. They then examined the levels of biochemical markers - proteins called peroxiredoxins - that are produced in high levels in blood and found that they underwent a 24-hour cycle. Peroxiredoxins are found in virtually all known organisms.

A further study, by scientists working together at the Universities of Edinburgh and Cambridge, and the Observatoire Oceanologique in Banyuls, France, found a similar 24-hour cycle in marine algae, indicating that internal body clocks have always been important, even for ancient forms of life.

The researchers in this study found the rhythms by sampling the peroxiredoxins in algae at regular intervals over several days. When the algae were kept in darkness, their DNA was no longer active, but the algae kept their circadian clocks ticking without active genes. Scientists had thought that the circadian clock was driven by gene activity, but both the algae and the red blood cells kept time without it.

The study has been published in the journal Nature. (ANI)