Fall 2004 Table of Contents.
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 New & Now.

Stories:

Battlefield Bacteria

The Last Word

Historic Disclosure

Genetically Altered

School for Scientists

Gravity Unbound

Papers and Profits

 

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Genetically Altered

According to the most recent edition of the Center for Disease Control's National Health and Nutrition Examination Survey, an estimated 17 percent of children and adolescents ages two to 19 are overweight.

Most of us are familiar with behavioral reasons: Overweight kids, often through no fault of their own, tend to get too little exercise, eat too much unhealthy food, and live in homes where neither exercise nor wholesome food is a priority. Far fewer Americans, however, are aware of the genetic basis for kids' weight gain; how, in the words of the CDC report, a child's "genes can influence how the body burns calories for energy and how the body stores fat."

Frederick vom Saal, a professor of biological sciences at MU, is working to advance our understanding of genes and weight gain. He has spent much of his career examining the endocrine disrupting effects of low-level chemical exposures, most notably bisphenol-A, which recently made news in San Francisco, where a controversial ordinance seeks to ban its use in children's products. Vom Saal's bisphenol-A research has, in turn, helped him to ask some important, and unsettling, questions about a possible relationship between a genetic predisposition to weight gain and pregnant women's exposure to certain chemicals.

According to vom Saal, fetal exposure to the endocrine-disrupting chemicals commonly found in plastic containers, pesticides, electronics and other products may change the functioning of a fetus's genes, altering a baby's metabolic system and predisposing him to obesity. "This individual could eat the same thing and exercise the same amount as someone with a normal metabolic system, but he or she would become obese, while the other person remained thin," he says.

Vom Saal aired these concerns during a symposium session at the 2007 annual meeting of the American Association for the Advancement of Science. They were based on a recently concluded study in which vom Saal demonstrated that, when pregnant mice were exposed to low levels of potentially endocrine-disrupting chemicals, their offspring were born at low weights. Tellingly, soon after birth members of these underweight litters began gaining weight very rapidly. Vom Saal went on to record the mice's body mass over the course of their lives. They remained fat.

Studies of low-birth-weight children have shown a similar pattern, vom Saal says. "The babies are born with a low body weight and a metabolic system that's been programmed for starvation. This is called a 'thrifty phenotype,' a system designed to maximize the use of all food taken into the body. The problem comes when the baby isn't born into a world of starvation, but into a world of fast food restaurants and fatty foods."

More research needs to be done to determine which chemicals cause this effect, he says. There are approximately 55,000 man-made chemicals in the world, and as many as 1,000 of those might fall into the category of "endocrine-disrupting."

"You inherit genes, but how those genes develop during your very early life also plays an important role in your propensity for obesity and disease," vom Saal says. "People who have abnormal metabolic systems have to live extremely different lifestyles in order to not be obese because their systems are malfunctioning. We need to figure out what we can do to understand and prevent this."

       
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Published by the Office of Research.

©2007 Curators of the University of Missouri. Click here to contact the editor.