The biological clock: What really makes us tick


Genetic circuitry key to array of human conditions, UH circadian scientists say

HOUSTON, March 25, 2004 From sleep patterns to health conditions, biological clocks get down to what makes us tick. The University of Houston is home to one of the world's leading centers for biological rhythms research. With five laboratories and a team of more than 30 scholars led by five tenured faculty members, the UH Biological Clocks Program studies an array of issues with far-reaching human implications.

Paul Hardin, a professor of biology and biochemistry at UH, primarily focuses on researching the molecular mechanisms that underlie circadian oscillators, which are biological clocks that control daily rhythms such as sleep-wake cycles and daily cycles of many hormones. By understanding this molecular circuitry that underlies biological rhythm function in the fruit fly (Drosophila melanogaster), Hardin is determining how daily rhythms in physiology and behavior found in many organisms are controlled by an innate, genetically encoded circadian clock. This research has allowed Hardin to be able to define certain genetic relationships that, in turn, led to the discovery that circadian oscillators can produce profound effects on the performance of animal sensory systems. His research with fruit flies, then, also is pertinent to biological clock function in mammals.

"Distinct rhythms are present in so many organisms, spanning the evolutionary chain of microbes, plants, animals and humans," Hardin said. "One of the main reasons for studying circadian rhythms is to uncover the impact they have on human health and well being. A better understanding of the function of these rhythms across species can help us evaluate the consequences of problems that occur when the clock is damaged in humans."

Also known as circadian rhythms, biological clocks offer scientific insight into depression and medication toxicity, as well as helps pinpoint peak attack times related to lung, heart and brain disorders. For instance, it has been found that cancer drug therapies are metabolized much better at certain times of the day. So, if physicians can pinpoint these ideal times and give those drugs when they do not metabolize and allow the body to clear them naturally, then side effects can be reduced while impact is maximized.

And with such vital signs as blood pressure and heart rate under the control of the circadian clock, respiratory, cardiac and cerebrovascular conditions that are dependent on these vitals also are on the way to being better understood. Asthma attacks, for example, primarily occur in the middle of the night, while peak time for heart attacks and strokes is typically mid morning.

The mystery behind biological clocks also is key to understanding how sleep-wake cycle disruptions lead to various types of depression and may ultimately uncover ways to better cope with shift work and jet lag.

Hardin's enthusiasm for this burgeoning field is obvious and his contributions significant. He was trained as a molecular geneticist, joining the UH faculty in 1995. He has won a number of awards for his research, among them the Aschoff-Honma Prize that he received this September in Japan. The award is presented every two years to a scientist working in the field of biological rhythms and currently carries a monetary award of one million yen (approximately $10,000). Hardin and his team also have grants from the National Institutes of Health, Department of Defense and NASA.

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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