November 2 SciCafe: Q&A with Bioluminescence and Biofluorescence Experts
by AMNH on
Museum scientists John Sparks and David Gruber have traveled the world in search of bioluminescent and biofluorescent organisms. On Wednesday, November 2, at 7 pm, the pair will host November’s SciCafe, Alive and Glowing: Adventures in Bioluminescence and Biofluorescence, and shed light on the way these phenomena have appeared throughout the tree of life. Dr. Sparks will also curate the Museum’s upcoming special exhibition Creatures of Light: Nature’s Bioluminescence, which opens March 31. Below, Sparks and Gruber answer a few questions about their enlightening research.
What’s the difference between bioluminescence and biofluorescence?
John Sparks: For an organism to biofluoresce, it must be illuminated by—in other words, absorb photons from—an external source of light. Turn off the light source, and there’s no fluorescence. In bioluminescence, the light-producing reaction takes place inside of an organism, requiring no external source of light. Some organisms combine both bioluminescence and biofluorescence, such as the jellyfish Aequorea.
How did bioluminescence first evolve, and how widespread is it across the tree of life?
David Gruber: Charles Darwin pondered this exact question in 1859, mentioning the perplexing problems bioluminescence posed to his theory of natural selection. Bioluminescence’s first evolutionary appearance was likely due to random mutations in non-luminescent organisms that produced a living glow. It may have started with antioxidant functions. Since sighted animals did not appear until after the Cambrian (542 million years ago), this metabolic antioxidant feature precedes the visual mating and predator avoidance displays we humans see—or can’t see—today.
JS: And the phenomenon of bioluminescence is remarkably widespread across the tree of life, ranging from single-celled bacteria, radiolarians, and dinoflagellates, to mushrooms, sharks, snails, and bony fishes. The widespread nature of bioluminescence throughout the tree of life and the vastly different chemistries used to produce light indicate that there have been numerous evolutionary origins of the phenomenon. It has been estimated that bioluminescence has evolved independently over 40 times, but this may be a severe underestimate.
Are there any medical or research applications of bioluminescent or biofluorescent mechanisms?
DG: Scientists, like all humans, are highly visual creatures, and these molecules are proving incredibly successful at illuminating previously invisible biological processes down to the cellular and molecular levels. For instance, recently developed green luminescent proteins derived from sea pansies and a red-emitting protein from a luminous click beetle are being used in cutting-edge cancer research. And applications of biofluorescent proteins from corals and jellyfish are now allowing neuroscientists to visualize the firing of single neurons in living brains.
Your research on ocean organisms has led you to some extreme environments. What was your wildest research trip?
JS: We were diving at night on Bloody Bay Wall off of Little Cayman Island in the Caribbean and using special lights and filters to capture coral fluorescence on the shear wall. It was rather disheartening on these evening dives to notice just how many sharks were becoming active and circling our team—while we could still see them. Once on the wall in the complete blackness, we had to focus on getting the images and staying level in the water, as the wall drops for 1,000 feet and one could get into serious trouble quickly if not paying attention. Facing the wall and just knowing all of those sharks were out there in the darkness was unnerving.