The seas in Southern California are aglow, and flowering plants are emitting their own light. It has been quite a week for bioluminescence!
Last September I was up in Maine at the Acadia Night Sky Festival with my family, and yes, the star parties, meteorite displays, and Bar Harbor restaurants were terrific, but at least as memorable as all of that was kayaking on Castine Harbor in the dark and observing bioluminescence up close. Tiny organisms in the water produce their own light when the water is disturbed, partly because the reaction that produces the glow requires oxygen, but also because the microorganisms have some kind of mechanism that makes them respond to shear stress. You strike the water with your oar, and it briefly lights up in a funky blue. Sometimes beads of the glowing blue stick to the boat — or to you!
So I’ve had it in the back of my mind ever since, but this week bioluminescence really bubbled up to the surface.
First of all, as Katherine J. Wu writes for Smithsonian Magazine, Southern California is in the midst of a bioluminescence bonanza, and it’s not clear just how long it will last. Some places on Earth like Vieques Island in Puerto Rico and Castine Harbor have stable bioluminescence all year round, but it’s fleeting in the few other places lucky enough to experience it at all.
Earlier this week, after noting a strengthening red tide at Newport Beach, California, and thinking he might have a chance to film something special, photographer Patrick Coyne went out on a boat one night and, after hours of frustration, he ultimately succeeded rather spectacularly:
Coyne, on his Instagram post, calls it “truly one of the most magical nights of my life,” but also explains how difficult it was to capture this footage.
As Linh Anh Cat writes for Forbes, the tiny organism responsible for the glow is Lingulodinium polyedra, and fortunately the Southern California version we’re now seeing does not seem to be harmful to humans.
Lingulodinium polyedra, and other marine plankton like it, called dinoflagellates, make bioluminescence using the reaction of oxygen with a chlorophyll-like molecule called luciferin:
This is done with the help of an enzyme (a protein that greatly speeds up chemical reactions) called luciferase.
“Luciferin” is actually a generic term, because different organisms have different forms of it. Fireflies, of course, have a luciferin that produces yellow light when it reacts with oxygen. But marine organisms like Lingulodinium polyedra have fine-tuned this reaction to emit bluish light so that it will be most visible through the water. Sea or lake water absorbs the other colors pretty well, but greenish-blue can travel the farthest (which is why the water looks bluish in the first place):
While the functions of bioluminescence in larger organisms like fish, worms, and fireflies are reasonably well understood, it’s not really clear why these tiny plankton emit light when they are agitated in the open water. But evolution would have gotten rid of it if it weren’t valuable to them for some reason. Maybe it saves them from some predators because eating things that glow strikes hungry sea creatures as weird.
I’m not a huge fan of mushrooms to begin with (except morels), but I would certainly never eat one that was glowing. Would you?
And that’s our segue into the other fun bioluminescence story this week: A team of Russian researchers provided tobacco plants with a few mushroom genes, enabling them to produce their own light.
There are various bioluminescent fungi out there, like the mushroom Neonothopanus gardneri, seen here in a time-lapse with waves of light emission roiling through it both day and night:
A still photo is perhaps a bit easier to look at:
Just three years ago, the chemistry of the mushroom’s light emission was explained by a collaboration among Russian, Japanese, and Brazilian scientists. The mushroom’s luciferin (called 3-hydroxyhispidin) is a lot simpler in structure than the one from dinoflagellates:
Plants don’t make 3-hydroxyhispidin naturally, but it turns out they only need a little bit of help to do so. Most plants already make plenty of caffeic acid, which they normally use to form lignin, pigments, tannins, and other things. (Caffeine isn’t made from caffeic acid, though, despite the name!) Adding just three genes from a Neonothopanus mushroom allows a plant to make 3-hydroxyhispidin from the caffeic acid it already has.
If those three genes, plus the mushroom’s gene for luciferase — to catalyze the light-producing reaction — are added to tobacco, then, as reported this week by Moscow-based researchers led by Ilia Yampolsky and Karen Sarkisyan, you get this:
That picture was taken in the dark (and to be fair, with a not-so-short exposure). The green light you see is not reflected from the plant, but rather it is emitted by the plant. Did flowering plants on Earth ever do this themselves? I don’t know, but if they did, it apparently didn’t stand the test of evolution.
You could make ornamental plants this way (and someone surely will), but they can be pretty valuable scientifically, too. You’re going to get light emission wherever and whenever caffeic acid is made in the plant, and because caffeic acid links up to some important plant functions, it’ll certainly help us learn about plant physiology and development. Take a look at this 32-second (and unfortunately non-embeddable) video as an example of the research value of these time-lapse images, but also their general coolness:
So …. this has been The Week of Bioluminescence! And that’s the way it is. I would like to thank bioluminescence for striking a two-fer and finally giving me an excuse to write about it!
Now, if you ever get the chance to check out bioluminescent waters in person, by all means do it, because it’s certainly worth it. But we’ll have to see about those glowing cucumbers when the time comes…...