Glow-in-the-dark Christmas Trees
lawrence writes "The BBC is carrying this story about five post-grad students at the University of Hertfordshire who are planning on creating a glow-in-the-dark christmas tree. They would do this by adding the genes that cause glowing in fireflies and jellyfish, making the pine-needles glow all the time. They expect the cost of the trees to be about £200 ($330) Future possibilities involve coral genes that would make it multicolored. " I think my favorite part about this story is the comment about Americans being a likely market. *grin*
Luciferase is a firefly gene that catalyzes the breakdown of the chemical luciferin, emitting light in the process. (Yellow light.) Fireflies "blink" by controlling the access of luciferase to luciferin. A plant isn't going to blink since it doesn't have the appropriate control machinery (e.g. no neurons to send a signal saying "turn on now"). But a plant could always simply glow steadily. Unfortunately, plants don't make luciferin, and normal luciferase doesn't catalyze anything in a normal non-firefly-light-organ cell. I presume that the postdocs have figured out a way to get around this.
Even stranger is the idea to use GFP. GFP (green fluorescent protein) is responsible for most of the neat pictures of glowing organisms that you're likely to see. However, what they don't tell you is that since it is fluorescent it requires violet or blue light as input. GFP absorbs violet or blue light, blah blah Stokes Shift blah blah, and emits green light. If you're going to shine blue light on your tree, why bother with all the confusing luciferase stuff and--if you want yellow--just include YFP as well (which works just like GFP except it emits yellow, or actually more chartreuse, light).
My guess as to what the group is really trying to do is this: find and use a luciferase-like gene that creates bioluminescence out of common cellular energy carriers, e.g. NADPH. Plants store the energy from sunlight in NADPH, so if you express this gene, they'd glow (at least during the day...). Furthermore, the reaction would ideally produce blue light. It's tough to get blue light out of a plant, because cholorphyll absorbs blue light. But if you tack on a GFP, it will convert the blue light to green and you'll be able to see it fine. Likewise for yellow with YFP. If you want orange or red, you can tack on both a GFP and a coral fluorescent protein, which will turn green light into an orangy color.
It makes a nice headline, but it sounds rather complicated to me. I wouldn't hold your breath for these trees.