Epigenetics: An Introduction
Generally, the focus of much easily accessible literature - and much teaching, at least in my limited experience - is focused on genes. Genes: They’re made of DNA, and code for mRNA, which codes for a protein. It’s the central dogma of molecular biology, one that nearly every biology student is familiar with.
So, then, how does one explain the so-called “mystery of the mice”?
As seen in the video above, there are two twin mice - they are genetically identical. They have all of the same genes, and yet, one mouse is fat and yellow (for lack of more scientific terms) and one mouse is thinner and brown. Therefore, it’s reasonable to infer that the difference in the mouse phenotypes has nothing to do with the genes they possess, and you’d be right: It has to do with the way the genes they possess are regulated. The yellow mouse has a gene called agouti that’s switched on all the time. The gene inappropriately blocks a receptor that tells the satiation centre of the mouse’s brain when it’s full - causing the yellow mouse to overeat its way into obesity, and a higher risk of mouse heart disease, mouse diabetes, mouse cancer, and ultimately, mouse death.
Any of those problems sound familiar?
The video is an excerpt from “A Ghost in Your Genes”, a NOVA documentary about the rise of epigenetics. As scientists scour the genome for genetic links to things like cancer and obesity, it’s worth noting that the answers don’t always lie in the genes themselves, but in the power of gene regulation on phenotype.
If you’re interested, the full programme “A Ghost in Your Genes” can be found here.