Tuesday, 20 March 2012

Mutation: A lack of myostatin exhibits abnormal muscle growth
Jeremy Tran (42916352)
Throughout our life, humans have grown from short to tall, from bones to brawn.  With muscles, they normally grow bigger through time, possibly accredited to our puberty stage in our teens. But why is it that there is a limit to how big muscles grow? What could be the explanation of why the potential of muscle growth is inhibited?

In the 20th century, livestock breeders noticed a difference in muscularity of their cattle. Being amateurs of science and genetics, these breeders selectively chose certain cattle to breed in hope of a discovery that would change the livestock market.

One would look normal like any other cattle yet the other would appear ripped full of muscle. Unbeknownst to them, this phenomenon of increased muscle mass can be explained by a certain gene mutation.

Dr Pherron and his team of geneticists at John Hopkins University investigated various proteins related to cell growth and the like. While investigating, he discovered that certain a gene responsible for controlled muscle mass, myostatin. Myostatin is primarily produced in the skeletal muscle cells and is secreted throughout the body where it circulates through blood. Myostatin acts as an inhibitor of muscle growth. There, it acts on muscle tissue to keep muscle growth in control ensuring it to grow within an optimal range.

Myostatin, a protein that the gene encodes is also a relative to a family of molecules known as the transforming growth factor beta (TGF-b). It can also be known as the differentiation factor-8 (GDF-8). However if muscle growth is abnormally big, it can possibly be explained by a mutation of the gene responsible for encoding myostatin that produces amounts less than normal. With less myostatin in the body, the less lenience of muscle growth it has on the body. Hence, the increase of muscle mass is reliant on how much the body produces myostatin protein.

With our high-tech revolutionized genetic technology, possibilities are endless. Intrigued by such phenomenon, scientists further explored the myostatin, in hope of using its characteristics and properties to their advantage. It is important to note that myostatin does not always exhibit muscle growth. It can also inhibit muscle growth with excessive amount of myostatin. With that in mind, scientists experimented using mice. By “knocking” out the gene responsible for encoding myostatin, they found those mice were twice as musclier as the normal mice.

Difference of muscle of mass of a controlled mouse and a mouse with less myostatin.
Such discovery of myostatin has paved a way for livestock breeders with bigger cattles, increasing competitiveness in the market. In addition, this can also be a potential cure for human muscle wasting disease.

This phenomenon also makes you think. High metabolism or hormone levels may not be the answer to why a person is skinny or why they can’t gain weight. It might just be myostatin.

Liam Hoekstra with lacking myostatin.
Video of Belgian blue (cows) with high muscle mass:


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