myostatin gene and muscle size
This is one of my favorite knockout animal models!
The myostatin gene in mice (and other animals) inhibits muscle growth and instead promotes deposition of fat. This gene is thought to have been evolutionarily conserved in order to promote formation of energy stores (fat) and restrict calorie consumption (by muscle) in animals who don’t have a guaranteed source of food. This makes sense because what animal knows for a fact that it will find something to eat every day? But, if this gene is knocked out in the laboratory setting or as a naturally occurring mutation (myostatin “knockout” mice), check out what happens: there is tremendous muscle hypertrophy and a significant reduction of body fat. There’s a reason why this animal model is called “Mighty Mouse”!
A view of the chest muscles of these mice:
A view of the muscles in the front and rear limbs (i.e. arms and legs):
For a more real-life example, the Belgian Blue Bull is naturally missing the myostatin gene:
I think I speak for everyone when I say, “Awesome!”
All of these images are taken from the original scientific article, which first described the function of the myostatin gene:
