[Posted by NIGHTSEA founder Charles Mazel]
In August 2019 my wife and I went on a wonderful ‘Alaska Glacier Country’ cruise with UnCruise Adventures in Alaska’s Inside Passage. Lots of up-close views of wildlife and spectacular scenery, with opportunities for exploring on kayaks, skiffs, and shore walks. All of the off-boat activities were led by knowledgeable and enthusiastic guides who were eager to spot things of interest and share them with the guests. On an exploration of the intertidal zone on Kuiu Island we came across a jellyfish in the shallow water. Our guides Kalyn and Bobby consulted their field life guide and identified it as Aequorea spp. They provided some nice information about jellies in general, but were not aware that this one in particular is phenomenally important – it is the source of the original discovery of green fluorescent protein (GFP). You can’t expect them to know everything, so I told them a bit about the discovery and significance of this magical protein. Bobby and Kalyn asked for more information, so I decided to put together this write-up, hopefully suitable for on-the-spot sharing during a shore excursion in the Alaskan wilderness. Bobby and Kalyn, this is for you and for all the expedition guides who add so much to our appreciation and understanding of the world around us.
The Jellyfish that Won the Nobel Prize
(Click any image for larger view)
(All images (c) Charles Mazel)
This particular jellyfish looks pretty ordinary but is really special – it won the Nobel Prize and is worth billions of dollars. Well, not the jellyfish itself, but a protein discovered within it led to a complete revolution in what you can image in biology, and the story of the discovery is a great example of the benefits that can pop out of doing science for the sake of science.
This jellyfish, named Aequorea, is bioluminescent. That is, it contains chemicals that it can mix to emit light by itself – like fireflies. The light appears in a ring of spots around the edge of the bell. A curious thing is that while the bioluminescence of marine organisms is usually blue, the light from this jellyfish is green. A scientist was studying this at a marine laboratory in Puget Sound in the early 1960’s. He discovered that there was an ordinary blue-light-producing bioluminescent reaction, but Aequorea had an additional protein that took up the energy and emitted green light instead. So the glow was coming not from the bioluminescent chemicals, but from this extra protein. And the protein was also strongly fluorescent – if you shone ultraviolet or blue light on it, that same green light would be emitted.
The scientist, Osamu Shimomura, collected thousands and thousands of the jellies so that he could extract, isolate, and study this protein, which became termed ‘green fluorescent protein’, or GFP. Living things are made mostly of proteins, and there are lots of things that fluoresce in nature, but in almost all cases the fluorescence does not come directly from the protein itself, but from another molecule that gets attached after the protein is made. What makes GFP special is that its fluorescence comes from the protein itself, with nothing else needed – if you make the protein you have fluorescence.
Proteins are manufactured in cells under the control of DNA. In the 1980’s scientists realized that if you could isolate the genetic sequence for GFP and attach it to the gene for something else you could add fluorescence to that thing. By getting the GFP marker to be expressed where you wanted it in an organism you had a phenomenal tool for viewing things directly – muscles, organs, blood cells, tumors, nerves, whatever. Another nice property of GFP is that it is a small protein, so when added it doesn’t interfere with normal biological functions. And since it is being added to the DNA the fluorescent properties can be passed on to the next generation. The video below shows larval zebrafish in which the blood cells have been labeled with GFP, enabling you to directly see blood flow. Note that you will see some zebrafish that are not showing this fluorescence – not all of them inherit the trait.
This was accomplished in the early 1990’s, and after that the rush was on. Researchers searched for new versions of this special protein, hoping for new or brighter colors. Some people were exploring in nature for similar proteins in other bioluminescent organisms, while others were manipulating the protein itself to create new variations. In the late ‘90’s it was discovered that the fluorescence from corals and anemones, which are NOT bioluminescent, also came from related proteins that behaved in the same way. People were out exploring the ocean for new varieties and even getting patents on corals and anemones!
If you explore the intertidal you may find more of these animals with magic fluorescent proteins. The green color in the Anthopleura anemone pictured on the left below, which we found in the same intertidal walk, comes from a protein of the same type. The second picture (from a different specimen, not from Alaska) shows an Anthopleura anemone fluorescing under blue light.
The value of this protein as a marker is incalculable. It is routinely used to tag biological features so that they can be studied at high resolution. You can use it to observe development of parts of an animal, essentially watching genes turn on and off. And sometimes it is used as a marker to help scientists select which members of the next generation carry other traits of interest. It contributes to research into an incredible range of biological functions and to investigations of many human diseases.
The importance of the protein from this jellyfish is so great that in 2008 three scientists – Shimomura for the original discovery, Martin Chalfie for first expressing the protein in an organism, and Roger Tsien for creating a veritable rainbow of GFP variants – shared the Nobel Prize in Chemistry.
Always be curious – even a nearly transparent, primitive organism like this jellyfish can harbor secrets that are incredibly important for science and medicine.