Research into the Circadian Rhythm

The mechanism which regulates the internal 24 hour cycle of all life from the cells of human beings to algae has been identified by researchers.

Two recent research studies from the journal Nature from the Universities of Cambridge and Edinburgh give some insight regarding the circadian rhythm which regulates daily and seasonal activity patterns, from sleeping cycles to migrations to flower blossoming.

One research study, from the University of Cambridge's Institute of Metabolic Science, has observed 24 hour rhythms within red blood cells. This is important since circadian rhythms have always been thought to be linked to DNA, but - different from most other cells in the body - red blood cells do not contain any DNA.

For the study, the researchers, funded by the Wellcome Trust, incubated pure red blood cells from volunteers in darkness and at normal body temperature, and continued to take samples at regular intervals for a period of several days. Then they observed the levels of biochemical markers which are created in high levels in blood and discovered that they underwent a 24 hour cycle. Peroxiredoxins are located in almost every known organism.

Another study, by researchers collaborating at the Universities of Edinburgh and Cambridge, and the Observatoire Oceanologique in Banyuls, France, observed a similar 24 hour clock in marine algae, suggesting that circadian rhythms have always been significant, even for primitive forms of life.

The scientists in this study located the rhythms by sampling the peroxiredoxins from algae at defined intervals over the course of several days. When the algae was kept in the dark, its DNA became inactive, but the algae kept its circadian rhythm ticking without active DNA. Scientists had previously thought that the circadian rhythm was controlled by DNA activity, but both the algae and the human red blood cells kept to their cycles without it.