Scientists breed 'mighty mouse'

Last week the papers were flooded with reports of a so-called 'mighty mouse' - a genetically engineered mouse able to run for up to six hours at a speed of 20 metres per minute before needing a rest - created by researchers based at Case Western Reserve University in Cleveland, Ohio. The research, published in the Journal of Biological Chemistry, will help scientists to gain a better understanding of the genes involved in metabolism and muscle strength in humans, potentially leading to new treatments for muscle wasting disorders like Duchene Muscular Dystrophy.

Professor Richard Hanson, who co-led the study, said that the special 'athletic' abilities of the mice are to do with the remarkable way in which they metabolise glucose in the blood. 'They are metabolically similar to Lance Armstrong biking up the Pyrenees; they utilize mainly fatty acids for energy and produce very little lactic acid', he said.

The researchers found that the mice also had other remarkable traits: although the new mice ate 60 per cent more, they were fitter and leaner than normal 'wild-type' mice and they had the ability to give birth at three years old - the equivalent of an 80 year old woman giving birth.

The new mice have been genetically engineered to express a glucose metabolising gene - PEPCK-C - to be over-expressed in the skeletal muscle, allowing them to avoid the muscle-cramping build-up of lactic acid which normal mice, and humans, experience during prolonged exercise.

The research has raised concerns that some athletes might resort to gene therapy to improve their performance, however Professor Hanson argues that this is unlikely. 'We humans have exactly the same gene. But this is not something you would do in a human. It's completely wrong. We do not think that this mouse model is an appropriate model for human gene therapy. It is currently not possible to introduce genes into the skeletal muscles of humans and it would not be ethical to even try'.

In future, the researchers plan to use the new mouse to study the effects of diet and exercise on longevity and cancer risk and potentially to better understand the genetic basis of inherited conditions which lead to muscle wasting in humans.