Scientists Genetically Engineer Mice With Super Endurance

How do you build a mouse that can run six-times farther than its average bretheren? Take away all its fast-twitch muscle fiber, along with its ability to contract its muscles.

According to ScienceNow, researchers at the University of Pennsylvania found the gene receptor that controls the protein responsible for muscle contraction. When they engineered mice to lack that protein, all the muscle in their body converted any fast twitch muscle (which is more powerful, but fatigues quicker) to slow twitch muscle fiber, which provided endurance gains.

But these behavioral quirks weren't quite enough to convince Khurana of the effect on muscles. Lack of the IL-15Rα gene could just be making the mice jittery or giving them extra energy. So the researchers dissected muscles from the longer-running mice. The muscles sported increased numbers of energy-generating mitochondria and more muscle fibers, indicating that they tired less easily. And when the researchers stimulated them with electricity, the muscles continued to contract for longer than normal, taking longer to use up their energy stores, the team reports in The Journal of Clinical Investigation.

The discovery of this gene could explain why some people are better endurance runners than others, and if discovered in humans (or any other animal, for that matter), could be used to create a human that could run and run and run and run. Although, the absence of speed and power might not be worth it.