In This Corner, Weighing 0.9 Ounces: Knockout Mouse!

While it’s certainly not ideal that scientists experiment on animals, it’s proven to be better than the alternative (i.e., experimenting on humans). The noble and adorable mouse is one of the most commonly-used laboratory animal, as they are relatively closely related to humans in terms of genetic similarity—humans and mice share a large number of genes. To test the effects of specific genes within the overall gene sequence, scientists frequently work with special genetically-modified mice called “knockout mice.”

knockout mouse

Gene Gene the Knockout Machine

In a knockout mouse, science has been used to inactivate or “knock out” an existing gene by replacing it or by disrupting it with a piece of artificial DNA. In modifying the creature’s gene structure, researchers can study the role of genes that have been sequenced, but whose functions are as yet undetermined. Observed differences in the knockout mouse’s behavior or physiology can be used to infer the probably function of the inactivated gene.

The first knockout mouse was created in 1989 by the power trio of Italian-American molecular geneticist Mario “Big Mario” Capecchi, English biologist Sir Martin “Big Marty” Evans, and British-American geneticist Oliver “Big Oli” Smithies. The technical details of how a knockout mouse is created are a bit much to get into here; suffice it to say that, for their efforts, Capecchi, Evans, and Smithies were awarded the Nobel Prize in Physiology/Medicine in 2007. Why it took 18 years for their achievement to be recognized is an Agatha Christie-caliber mystery.

Mighty Mouse

Since their “invention,” knockout mice have been used to model and study numerous diseases and maladies, including anxiety, arthritis, cancer, diabetes, heart disease, obesity, and Parkinson’s disease. They are also used to provide a biological and scientific context for the development and testing of drugs and other therapy techniques.

Millions of knockout mice are used in scientific and medical experiments every year, and thousands of different strains of knockout mice have been developed. Many different variations of the technology used to create them, as well as the modified mice themselves, have been patented by private companies.

Though gene knockout is most easily achieved in mice, other research animals can be “knocked out,” as well. Knockout rats have been used in research since 2003, but knockout rats are much more difficult to create than knockout mice.

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