Why These Eels Glow Green and What It Could Mean for People

Gymnothorax zonipectis fluorescent eel (Photo © John Sparks)

By Lida Tunesi

Researchers from the Graduate Center, Baruch College, and the American Museum of Natural History have identified a protein in the barred-fin moray eel that causes the eel to glow green. For humans, the protein could offer a new way to test for jaundice in newborns.

The new paper, co-authored by two Graduate Center Biology Ph.D. students, was published in Frontiers in Marine Science.

The discovery comes 10 years after scientists captured an image of a bioluminescent eel for the first time off the coast of the Cayman Islands and is the first identification of a fluorescent protein in any moray eel, adding to the growing list and awareness of biofluorescent fish.

“We are starting to realize how widespread fluorescence is in marine life, particularly in eels,” said Ph.D. student Andrew Guarnaccia (Biology), who was first author on the paper. “This is now the third family of eels to contain this type of fluorescent protein, and I’m sure that we will find representatives in most, if not all, of the remaining families.”

“We have been studying eels for a few years now,” said co-author Professor Jean Gaffney (GC/Baruch; Biology, Chemistry/Natural Sciences). “Our interests are primarily focused on the discovery of fluorescent proteins, but we are also excited about potential applications.”

This type of eel protein, known as a fluorescent fatty acid binding protein, gives off light in the presence of a substance called bilirubin. Bilirubin occurs naturally in humans as a result of normal red blood cell breakdown, but too much of it can be a sign of problems with the liver or bile duct. Following up on a patent that Gaffney, Gruber, and Vincent Pieribone of Yale University were awarded in 2018, this type of protein could offer a new way to test bilirubin levels in infants that would be more accurate and use less blood than current methods. 

Researchers don’t know why the eels have the protein, however.

“This study raises intrigue as to what role the glowing molecule plays in these mysterious marine eels,” said co-author Professor David Gruber (GC/Baruch, Biology/Natural Sciences). “It may be related to attracting each other for full moon mating events.”

Gaffney previously received a National Science Foundation CAREER grant that partly funded the new work. The first two authors on the study, Guarnaccia and Sara Krivoshik, are fifth-year Ph.D. students in Gaffney’s lab.

“Andrew took the lead on this work and played a very major role in writing the paper,” Gaffney said. “Both Andrew and Sara are amazing students, and I am very lucky to have them in my lab.”

Professor John Sparks (Biology), who is a curator of ichthyology at the American Museum of Natural History, was also an author on the study.

Published by the Office of Communications and Marketing

Submitted on: OCT 7, 2021

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