This past month, our lab picked up the latest version of a 'genetically encoded calcium indicator' known as GCaMP from the GENIE project at Janelia Farm. Below is an example of calcium levels changing inside of neurons. GCaMP utilizes GFP (green fluorescent protein) to fluoresce brightly as calcium concentrations rise and then dims as calcium levels drop (note the movie has been false-colored to improve contrast, and to look cool, of course):
GCaMP movie
Claudia E. Mills at the University of Washington knows these creatures, Aequorea, in great detail and has some answers:
Aequorea has been silently drifting in the ocean for 160,000,000 years. To date, we still do not know exactly for what purpose these jellyfish glow.
Sources:
Mills, C.E. 1999-present. Bioluminescence of Aequorea, a hydromedusa. Electronic internet document available at http://faculty.washington.edu/cemills/Aequorea.html.
Shimomura, O., Journal of Microscopy, Vol. 217, Pt 1 January 2005, pp. 3–15
http://www.cooperlab.wustl.edu/PracticalAdvice/Shimomura2005.pdf
After some intense left-brain activity, analyzing these data, I kind of just wanted to take a minute to think about the source of GFP, the crystal jellyfish. Some of the best crystal jellyfish stories are from the accounts of nobel-laureate Osamu Shimomura, who started his quest to understand the bioluminescent glow back in 1961 off the coast of Washington state. Shimomura's advisor, Dr. Frank Johnson, constructed a chopping device, so that they could plow through tens of thousands of these creatures. The unknown glowing substance was then squeezed out, as 'the squeezate', for further purification and analysis. Fifty years later, everything has been solved - the chemical details, genetic code and crystal structure of two molecules essential to the natural process: aequorin and GFP. Over the years, things have been shuffled around to generate brighter greens and better calcium grabbers.
Wait a minute, I just spent my time writing about the details of a tragic end to 50,000 mysterious creatures as they were scooped out of the ocean and slapped down onto the chopping blocks. Oh, my ... I need to make sure that this little organism is alive and well.
Claudia E. Mills at the University of Washington knows these creatures, Aequorea, in great detail and has some answers:
I am relieved to find that those fervent scientists of the 1960's were not responsible for a major depletion of our jelly friend. Reading through her facts, you will quickly notice an impassioned rant on the misrepresentation of Aequorea in the popular news media - things being false colored green for the most part. As it turns out, the glowing substance does not permeate the entire jelly, but precisely exists around the edge of his dome, hence the special chopping device that dissected out the rim. My first thoughts are 'well, this scientist is over-reacting - really what's the harm in a little photo-shopping to get the green-glow idea across?' Then I read her statement:
I am increasingly concerned that people studying green fluorescent protein recognize neither the animal from which it derives nor natural fluorescence when they see it. The "cool inner light" (phrase used in opening text of the Science News article, vol. 152, p. 55) of the above-mentioned photo was actually reflected light from the photographer's flash, not fluorescence. This article has inadvertently highlighted the growing gap between the reductionist and the naturalist in science.
The 'growing gap'. As scientific finding builds upon scientific finding, we do become distanced from the organism itself. Perhaps the best discoveries by Shimomura were made when he was closest to the natural home of the jellyfish. For many months, he had a tough time deciphering the luminescent reaction. He finally developed the correct hypothesis after long hours, close to the sea, quietly thinking...
I often meditated on the problem on a drifting rowing boat under clear summer skies. Friday Harbor in summer at that time was quiet and peaceful, quite different from the present day, when it is saturated with busy pleasure boats and noisy seaplanes. Meditation afloat was safe but if I fell asleep the boat was carried away by the tide so that I had to row for a long time to get back to the laboratory.
Aequorea has been silently drifting in the ocean for 160,000,000 years. To date, we still do not know exactly for what purpose these jellyfish glow.
Sources:
Mills, C.E. 1999-present. Bioluminescence of Aequorea, a hydromedusa. Electronic internet document available at http://faculty.washington.edu/cemills/Aequorea.html.
Shimomura, O., Journal of Microscopy, Vol. 217, Pt 1 January 2005, pp. 3–15
http://www.cooperlab.wustl.edu/PracticalAdvice/Shimomura2005.pdf
I like your take on materials that originated naturally and how far separated they have become from the original creature they were extracted from. It sounds like enhancing GFP for scientific purposes may have changed it into something far removed from it's natural state, and I can see how someone working in a lab may not have a real feel for or as much reverence for the creature as Shimomura...even though he killed so many. I do get the impression that humans see nature as something to decode and then improve upon, despite how amazing it already is. It also appears that some people may have a heightened expectation of "wow factor" falsely gained from photos that have been manipulated to increase contrast for the purpose of observation. The story about Shimomura is a valuable one, I hope that more scientists grow this interest in the natural world :)
ReplyDeleteI really want to see this jellyfish glow in real life! I think that we enhance images in order to emote to our audience. It is as though we have seen this really cool thing and want to express our excitement about it to others - color helps a little, but never quite gets there.
ReplyDeleteGFP has been an extraordinary gift from nature to biomedical science (there are at least 24,674 publications that list GFP as a keyword). It has revolutionized our ability to observe life in action. In return, the very least we can do is value the environment and protect the ocean.