November 14, 2013
Investigating The Slimy Bioluminscence Of A Hidden Sea Worm
April Flowers for redOrbit.com - Your Universe Online
A new study, led by Scripps Institution of Oceanography at UC San Diego, is investigating the mechanisms behind a little-known marine worm that produces a dazzling bioluminescent display in the form of puffs of blue light, released into seawater.
The Chaetopterus marine worm, commonly known as the "parchment tube worm" due to the opaque, cocoon-like cylinders where it makes its home, is found around the world in muddy environments, from shallow bays to deep canyons. The light produced by the worms is secreted as a slimy bioluminescent mucus, which the worms are able to secrete out of any part of their body.
This slime hasn't been studied by scientists in more than 50 years. Two recent studies, however, have helped to reignite a determination to decode the inner workings of the worm's glow.
One study, conducted by Scripps Associate Research Scientist Dimitri Deheyn and his colleagues at Georgetown University, described details of Chaetopterus’ light production as never before. The findings, published in Physiological and Biochemical Zoology, were based on data derived from experiments conducted inside Scripps Oceanography’s Experimental Aquarium. The researchers used this data to characterize specific features of the worm’s light, tracing back its generation to a specific “photoprotein” tied to bioluminescence.
“The fact that the light is produced as a long glow without direct oxygen consumption is attractive for a range of future biotechnological applications,” added Deheyn, whose current work focuses on identifying the specific protein(s) involved in the light production.
The other study focused on the general biochemistry and optical properties of the light production. “We have shown that the mucus produces a long-lasting glow of blue light, which is unique for this environment where bioluminescence is usually produced as short-lived flashes of light in the green spectrum, especially for benthic (seafloor) species,” said Deheyn. He added that green travels farther and is therefore the easier to detect in shallow coastal environments.
The research team speculates that the luminous mucus may have several ecological functions, including serving as a trap to attract prey, a deterrent to ward off certain unwelcome guests to the worm’s living areas (the glowing mucus could stick to an intruder, making it more visible to its own predators), or possibly serving as a substance to build the worms’ flaky, tube-shaped homes.
The blue color, however, makes it intriguing and difficult to reconcile with a visual function for shallow animals.
“However, one can imagine that blue light would work better if the predator is a fish coming from greater depths, or for specific predators for which we still don’t know the visual sensitivity,” concluded Deheyn.
In a separate study, published in Photochemistry and Photobiology, Deheyn and his colleagues at Connecticut College found that riboflavin, known as vitamin B2 and used widely as a dietary supplement, is a key source of the light production.
The team focused on worms collected by Scripps Marine Collector and Technician Phil Zerofski in the La Jolla submarine canyon off the coast of San Diego, California, finding that riboflavin is a major fluorescent compound in all extracts of the worm’s luminescent material, including the glowing slime. While further study is needed, the researchers hypothesize that a derivative of riboflavin serves as the emitting force in the worm’s light-production process.
The worms do not produce riboflavin on their own, only plants and microbes can. The worms must acquire the vitamin through a food source, the same way humans do.
“We have shown that the bioluminescent light production involves riboflavin, which is key because it means that the worm is relying on an external source,” said Deheyn. “We suggest the light production depends on the worm’s diet, yet it could also involve a symbiosis with bacteria (possibly living in the tube) to provide the riboflavin.”
Continuing investigations are focusing on the intricacies of the chemical reactions behind the light production and methods to synthesize the light production in the laboratory.