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Sunday, 12 January, 2003, 00:19 GMT
One switch 'controls body clock'
Professor James and Professor Dorothy Morre
A husband and wife team made the breakthrough
The body's internal 24-hour biological clock is controlled by a single protein, say scientists.

The husband and wife team at Purdue University, Indiana, who have come up with the theory say it could lead to new ways to help people whose internal clock has been disrupted by jet lag or health problems.

But other experts in the field say the control of the body's natural rhythms is likely to be a great deal more complex.

This discovery holds myriad potential applications, from minimizing jet lag to determining when best to administer cancer drugs

Professor James Morre
Professor James Morre and his wife Professor Dorothy Morre say the as yet unnamed protein is responsible for determining when the body's cells are active or inactive.

They found that if the protein is altered, the body's clock is thrown into turmoil - and an internal "day" can last for as long as 42 hours.

Professor James Morre said: "We can now begin to understand the complex chain of events that connect the clock to events in the body.

"Since the clock affects nearly every bodily activity, this discovery holds myriad potential applications, from minimizing jet lag to determining when best to administer cancer drugs."

Growth cycle

The Morres had already discovered that cells have a 24-minute growth cycle, they enlarge themselves for 12 minutes, and then rest for 12 before growing again.

Now they have isolated a single cylinder-shaped protein molecule which appears to control both growth and rest phases of the cellular cycle.

Professor James Morre said: "Our model is that of a Janus-head protein with two opposing faces.

"One 'face' handles cell enlargement. Then the protein 'flips over,' allowing the second face to carry out other activities while cell enlargement rests."

While two functions from a single protein have been seen before, the precisely timed alternation of these functions has not.

Disrupted time

To confirm that the protein was responsible not just for regulating growth but for all activities set by the biological clock, the researchers isolated the gene which produces the protein within the body's cells.

They then cloned the protein and altered it in ways that produced different period lengths.

Professor James Morre said: "We found that we could produce clocks with cycles of between 22 and 42 minutes.

"The 'day' which the cell experienced was precisely 60 times the period length of the protein's cycle."

The researchers said the finding could help work into a wide range of subjects, including heart rhythms, sleep and response to drugs.

Theory doubted

However, Dr Martin Zatz, editor of the Journal of Biological Rhythms, told BBC News Online that regulation of the body clock was probably more complex than the theory suggested.

He said a handful of genes had been identified in which mutations disrupted the body clock.

And he rejected the idea that cell cycles of around 20 minutes could be conveniently multiplied by 60 to come up with the basis of a daily rhythm.

The research is published in the journal Biochemistry.

See also:

23 Dec 01 | Health
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27 Apr 00 | Health
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