Monday, December 10, 2007
Meet the 'Lance Armstrong mouse'
Imagine if you could live longer, be super fit, bear children at age 85 and had the ability to not only be able to run marathons, but to have an unquenchable desire for extreme exercise.
Well, all this is possible - if you're a mouse.
Researchers at Case Western Reserve University School of Medicine have created a new breed of mouse that some people are affectionately calling the "Lance Armstrong mouse."
Physiologically, these mice produce less lactic acid during exercise. That means their muscles can go longer and harder without major fatigue, a trait that was identified in Lance Armstrong by exercise physiology researchers at the University of Texas at Austin. But the wonders of the mighty mice don't stop there.
These mice can run for more than five hours straight, long after their normal rodent counterparts have given up and fallen off the treadmill. This endurance is due in part to their bodies' producing more mitochondria. For those of you who don't remember middle-school biology, mitochondria are a cell's powerhouse. The mice could run an incredible 5 km at 20 meters/minute. You can see the mice running alongside a normal mouse by clicking here http://www.cnn.com/video/#/video/health/2007/12/10/vo.mighty.mice.cnn. The lab subjects also ate 60 percent more food than the average mouse, but weighed only half as much. These mice burned just their fat when they exercised, resulting in being leaner and eating more to recover. All in all, they not only lived longer than other mice, but they could reproduce at older ages. The female mice were able to have a baby when they were nearly 3 years old -- that's 85 in mouse years.
How did scientists make such a mighty mouse? They came in the form of transgenic mice -- a mouse that was genetically manipulated to research a specific gene or enzyme. Case Western University researchers engineered lab mice to have an overabundance of an enzyme called phosphenolpyruvate carboxykinase or PEPCK (pronounced pepsi-K) in their muscles. The enzyme can be found in the livers and kidneys of all animals including humans.
Manipulating lab mice is a common practice in science. "In general, mice are the preferred choice because of their size, breeding efficiency and short gestation time," according to Dr. Karen Wu, a physiology researcher at Columbia University. Furthermore, mice and humans are 99 percent genetically similar according to a 2002 mapping of the mouse genome in Nature magazine. In fact, the same researchers said that 90 percent of genes associated with disease are the same in humans and mice.
But hold on. Don't expect PEPCK to show up in pills, shots or supplements anytime soon.
"I wouldn't dream of putting these genes in humans!" warns Dr. Richard Hanson of Case Western. "The process just wouldn't be possible in humans." Regardless of human applications, the news wasn't all good for the supermice. They are very hyperactive, aggressive and their intelligence has yet to be measured.
What do you think of the mighty mouse or supermouse? Do you think we'll ever see such traits in humans?
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