01.09.08

Looking for a Link

Posted in Biology at the University of Virginia, Body Clock, Nocturnin, The Oscar Show, UVa College of Arts & Sciences, University of Virginia, biology, circadian rhythms, evolution, hypothalamus, metabolism, physical health at 12:15 pm by Jacob Canon

In today’s show, adapted from an article published on the Oscar web site written by Fariss Samarrai, we discuss the research of Carla Green, associate professor of biology at the University of Virginia, and a study she headed which says that the gene Nocturnin, working within the network of the body’s circadian clock, appears to be particularly important in the control of metabolism.

The body’s biological clock has been shown to regulate life’s activity/rest cycles by controlling energy levels, alertness, growth, moods and the effects of aging. Further study has revealed that these internal clocks are controlled by circadian rhythms. Rhythms that were established early in the history of life on the planet and evolved associated with the astronomical cycles that effect Earth’s environment such as the rise and setting of the sun and the passing of seasons. What is now being discovered is that certain elements, already known to be part of the body’s circadian network, may have a broader influence on the life of an individual.

In a study published in the journal, Proceedings of the National Academy of Sciences, Associate Professor of Biology at the University of Virginia Carla Green and her colleagues discovered that the gene Nocturnin, which participates in the regulation of the body’s biological rhythms, may also be a major control in regulating metabolism. The study showed that mice lacking the gene were resistant to weight gain when put on a high fat diet and also were resistant to the accumulation of fat in the liver.

Professor Green, said, “It’s been known for some time that there are many links between the circadian clock and various aspects of physiology and metabolism. This study suggests that Nocturnin is part of the network that the circadian clock uses to control important aspects of metabolism.”

In the study, Green and her colleagues, Nicholas Douris, a U.Va. graduate student who designed the study, U.Va. post-doctoral fellow Shihoko Kojima and Joseph Besharse of the Medical College of Wisconsin, used regular mice and genetically altered mice in which the Nocturnin gene was not present. The Nocturnin-deficient mice were divided into two groups; one group fed a normal diet, the other a very high fat diet. A group of normal mice were also fed a high fat diet.

The researchers found that both groups of genetically altered mice maintained normal weight and activity levels, and, of particular interest, the ones fed the high fat diet exhibited only slight weight gains, even over long periods of time. However, the normal mice on the high fat diet ballooned, gaining more than twice the weight of the Nocturnin-deficient mice. And, when the mice were dissected, the researchers found that the normal mice had, as expected, large concentrations of fat in their livers, whereas the altered mice had normal levels of fat.

Green said, “We were quite amazed at what we found. We thought that over time, as we continued to feed the mutant mice the high fat diet that they would eventually gain weight at some expected rate, but it never happened. These mice continued to stay slim while the normal mice nearly doubled in weight and developed fatty livers.”

Clock genes in the body’s organs operate in conjunction with a central time keeper in the brain, the hypothalamic suprachiasmatic nucleus, but also work somewhat independently, resulting in a complex system of oscillators regulating various functions of the body. Scientists are working to better understand how the genes and proteins of the circadian clock in mammals affect not only activity cycles but also rates of metabolism, which are tied to feeding cycles. Green said it is possible that, “A better understanding of Nocturnin’s function could eventually lead to medical treatments that could counteract the problems of obesity, which has become a major issue in modern society.”

We look forward to the continued study of this important new finding in the hope that its potentially far reaching health benefits will be realized in our lifetime.

You’ve been listening to the Oscar Show… I’m Jacob Canon. Join us next week when our topic will be UVa professor and chair of biomedical engineering Thomas Skalak and his efforts to develop real scientific evidence about the effectiveness of magnetic therapy.

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