Earthworm’s Glow Unearthed

In the forest soils of Siberia, there is a tiny worm that will emit blue light if given a little tickle. The critter, known scientifically as Fridericia heliota, gets its glow via the oxidation of a previously unknown luciferin compound facilitated by a luciferase enzyme. This is the same mechanism that many bioluminescent creatures, including fireflies and certain jellyfish, use to produce so-called cold light. To date, only a handful of luciferin analogs have been chemically characterized. Researchers led by Ilia V. Yampolsky of the Russian Academy of Sciences’ Institute of Bioorganic Chemistry wanted to know precisely which chemical made F. heliota glow. The team collected approximately 60,000 of the little worms, each of which is only about 15 mm long, and then extracted their bioluminescent components (Angew. Chem. Int. Ed. 2014, DOI: 10.1002/anie.201400529). The researchers were able to isolate only 0.005 mg of the color-giving chemical from which they could do limited NMR and mass spectral analyses. Using these studies, they narrowed down the structural possibilities to four isomeric peptides and then synthesized them. One of the synthesized compounds (shown) turned out to be a match with the natural Siberian worm luciferin and produced light when mixed with crude Fridericia luciferase.