Friday, September 11, 2015

Gene You're Positively Glowing!

Out on the beaches of the Pacific is a group of heroes. A squad of jiggly life savers, spending their days scanning the surf, waiting for their moment to pull you back from oblivion... 

What!? Oh God...NO. Get your head out of the gutter, uck! What the heck is wrong with you? I'm talking about jellyfish; specifically the water jelly (Aequorea victoria), they're also called crystal jellies and have many other common names, so for this post we'll just call them Aequorea (pronounced: ay-core-ee-uh). 

Just as much acting talent in this photo, as in the one above it.
Courtesy: Denise Allen via Flickr

Now we've often declared our love for jellies. In fact this isn't the first time they've appeared on Depth and Taxa. If you want to get a refresher on the jelly life cycle, and learn about one of Aequorea's cousins check out the older post here. But Aequorea are especially interesting thanks to their contributions to the field of medicine. You might be picturing some kind of Doogie Howser scenario with a jelly subbing in for Neil Patrick Harris, and you'd be right to want to watch that. But what Aequorea have provided for humanity goes beyond just caring for sick individuals, and making us laugh Tuesdays at eight on ABC.

At first glance Aequorea only possess a simple elegance. They're completely clear, and don't have particularly flashy innards like some species. The wagon wheel-like structure inside their umbrellas is a system of canals that distribute nutrients around the jellies' bodies. But radial canals are a basic part of jelly structure, so although they're pretty, they aren't particularly distinctive. To see what has made Aequorea so important to humanity we need to take the lights down.

Oh man, those damn ravers keep leaving their trash everywhere...
Courtesy: William Ward via The Encyclopedia of Life

That ring is the outline of the bell margin of an Aequorea jelly. The glow you see is naturally produced by the jelly itself. Interestingly, we don't know for sure why these jellies produce this light. They don't constantly flash like fireflies, nor do they glow continuously like the stage at a Deadmau5 show. For the most part we've only observed Aequorea glow after they've been jostled by a human. Even if we don't understand why Aequorea glow, scientists have spent a lot of time figuring out how they do it.

In the 1960's, while trying to isolate the glowing material from Aequorea jellies, Dr. Osamu Shimomura and his team determined that a pair of proteins is actually responsible for producing this jelly's light. The first in this dynamic duo is a molecule called aequorin. Aequorin emits blue light when it's exposed to calcium ions. The second protein, which produces that green fluorescent glow we see is called... green fluorescent protein. Points for clarity I guess. Green fluorescent protein, or GFP, only glows when exposed to light in the same spectrum as the light produced by aequorin. So first, calcium ions flow into the aequorin which flashes blue, then the blue light hits the GFP which absorbs it, and then the GFP releases some of the energy it absorbed as green light.

Okay so how is glowing protein helpful to medicine? Well it's what triggers the glow in these proteins that's important. See calcium is an important trigger in both the nervous and muscular system. Calcium ions flowing into nerves spark them to send out the chemicals that transmit information between themselves and the next nerve in the chain. Scientists can inject aequorin into the area around a nerve and figure out where and when the calcium is flowing to the cell by seeing when the aequorin glows! This is incredibly useful when studying nervous systems because you can actually observe a nerve functioning, which is normally an invisible process.

Aequorin being activated by a calcium solution.

So aequorin is pretty cool, but it's green fluorescent protein that has really changed the landscape of cell research. GFP normally absorbs the light from aequorin to glow, but will also absorb light from the nearby UV spectrum. So that same black-light you used to make that Bob Marley poster look so cool in your dorm can be used to peer into the chemicals that sustain life itself.

Scientists managed to clone the green fluorescent protein and ever since have been attaching it to other proteins to watch how they're made, where they go, and how long they last inside the bodies of different animals. Dozens of fluorescent proteins, in several colors, have been created from GFP and others have been found in animals like sea anemones. Mice have been genetically modified with GFP tagged normal cells and glowing red protein tagged cancer cells. When observed under black-light scientists can actually watch how the cancer cells grow and spread in real time without harming the mice.

The thing that makes GFP so powerful is that it can be added to almost any cell or protein. So if you have a question about how fetuses develop, tag an egg cell with GFP and watch it divide. If you want to watch nerves grow as a mouse learns, tag their brains with GFP, and see them think. If you want to release a bunch of infertile male mosquitoes into a population to eliminate malaria without pesticides. Tag their testicles with GFP so you can sort the boys from the girls, and get to sterilizing. All of these things have actually been done using modern genetic techniques and a variety of fluorescent proteins.

These are the nerve cells in a mouse's brain expressing different chemical signals.
You're observing this animal's brain tell its body how to function
Courtesy: ZEISS Microscopy via Flickr 

Okay so maybe it isn't Aequorea itself that'll save your life. Mostly they'll keep eating plankton and washing up on shore like they've been doing for millions of years. But if it weren't for Aequorea's development of GFP we would probably never have been able to discover all that we have about living things, especially our own bodies. Animals and plants shouldn't be protected and preserved solely for their potential usefulness, but if one of the least noteworthy jellies can single tentacledly spark an entire research industry; imagine what else we can learn from the "nobodies" on the tree of life.


Nikon's Microscopy U,
Accessed via:

The GFP Site; From professor Marc Zimmer at Connecticut College.
Accessed via:

Mills, C.E. 1999-present. Bioluminescence of Aequorea, a hydromedusa. Electronic internet document available at Published by the author, web page established June 1999, last updated January 11th 2009

Shimomura, O., "The Discovery of Aerquorin and Green Fluorescent Protein", Journal of Microscopy, Vol. 217 Pt. 1, Jan. 2005, pg. 3-15.