The Science behind Glofish

I was wandering through the halls of Petsmart, filled with canaries, ball pythons, and dog toys, but I was mesmerized by a fish. At first, I thought it was an ordinary zebrafish. But when it peered from its underwater alcove, I saw that it was literally glowing.

Glofish are a product of genetic engineering, meaning that humans have altered the DNA of ordinary fish to make them glow. This is done through the addition of GFP (green fluorescent protein), which is originally from jellyfish, through a technology called CRISPR. CRISPR is made up of an enzyme, also known as Cas 9, and an RNA sequence. Enzymes are proteins which can do specific tasks because they have a hole that can only fit certain things, like how a key fits in a lock. Cas-9 is very useful because it only binds to the DNA sequence that matches the RNA sequence that it has. This means that scientists can carefully cut the DNA at the right spot and insert the glowing gene, GFP.

How does GFP work? GFP fluoresces. The main difference between bioluminescence and fluorescence is that while bioluminescence requires a chemical reaction to start, fluorescence needs light. Fluorescence basically takes the energy from that light and converts it into light emitted in a different wavelength. So, when these GFP organisms are shined under a blacklight, which is made out of ultraviolet light, they absorb the ultraviolet light, and emit green light. Red has the lowest wavelength and has the lowest energy in visible light, while violet has the highest wavelength and highest energy in visible light. Wavelength is the distance from the top of one wave to another. So, in violet light, the waves are closely packed together, a lower wavelength, resulting in more energy. Ultraviolet light is basically light that we can’t see, which has a higher energy and lower wavelength than violet light, so it is ultra-violet. This high energy light which we can’t see is absorbed and emitted as green light that we can see.

Since the GFP is inside the DNA and not just a pigment, the glowing can be passed down through generations. And interestingly enough, GFP is a reporter gene, so the specimen glows if CRISPR has succeeded. If GFP is added with another gene, you can see if the other gene has been added successfully.

Even though there are still a lot of things to tweak and discover, Glofish provides an illuminating example of transgenic technology found everyday.