RIPPLE MARKS: THE STORY BEHIND THE STORY Bioluminescent, Biofluorescent Species Light the Way to New Biomedical Discoveries

By Cheryl Lyn Dybas

The bioluminescent crystal jellyfish Aequorea victoria. Image Credit: Sierra Blakely, Wikimedia Commons

Throughout history, humans have been an animal such as a jellyfish or eel absorbs leap forward. For example, in the seven- fascinated with the “living light” produced light and re-emits it in a different color. teenth century, Anton van Leeuwenhoek by luminescent organisms. Today, the Now, “a vast range of analytical tech- invented the microscope. A new world glimmering power of bioluminescence niques has been developed based on opened. Scientists could suddenly has been harnessed for lifesaving uses bioluminescence,” write Zinaida Kaskova, observe previously unknown bacteria and in medicine, from lighting up structures Aleksandra Tsarkova, and Ilia Yampolsky blood cells. So it is with fluorescent pro- inside the brain to illuminating the pro- of the Russian Academy of Sciences and teins, Pieribone says. gression of cancer cells. the Pirogov Russian National Research One of the first accounts of biolumines- Medical University in a 2016 paper in BRIGHT GREEN EEL PATENT cence and health was written in 77 CE. In Chemical Society Reviews. Based on a bright green fluorescent pro- Historia Naturalis, Roman physician and “Immunoassays, gene expression tein found in two fish—the false moray naturalist Pliny the Elder described medic- assays, drug screening, bioimaging of live eels Kaupichthys hyoproroides and inal substances derived from aquatic ani- organisms, cancer studies, and the inves- Kaupichthys n. sp.—Pieribone’s team mals, including pulmo marinus. A jellyfish tigation of infectious diseases,” the scien- was awarded a patent for a new method now known as Pelagia noctiluca, Latin for tists state, are just the beginning of a tale of detecting bilirubin in blood or urine. “night light of the sea,” the species emits of 1,001 lights, as the researchers refer to Bilirubin is produced in bone marrow cells a glowing substance from the outer edge the growing number of bioluminescence and in the liver as the end product of red of its bell. When boiled in water or taken discoveries with applications in medicine. blood cell (hemoglobin) breakdown. in wine, Pliny believed, pulmo marinus High levels of bilirubin may indicate treated “the gravell and the stone.” A REVOLUTION IN SCIENCE liver damage or other disease. Molecular Also in the first century, Greek physi- An early chapter in the tale of 1,001 lights, Tools LLC, a biotech company in Frederick, cian and botanist Pedanius Dioscorides according to neurobiologist Vincent Maryland, is working with the scientists to posited in De Materia Medica, an herbal Pieribone, director of the John B. Pierce develop new ways of testing for bilirubin medicine encyclopedia he penned, that Laboratory at the Yale University School based on these proteins. “pulmo marinus being beaten small whilst of Medicine, is green fluorescent protein it is new and so applied, doth help such as (GFP). GFP is found in the crystal jelly- are troubled with chillblanes and such as fish Aequorea victoria. This and other ye have goute.” fluorescent proteins have revolutionized Some two thousand years have passed research in fields from immunology to since the time of Pliny and Dioscorides. neuroscience. Only recently, however, have researchers Many organisms are now known to discovered exactly how bioluminescence manufacture fluorescent proteins. “These is created, let alone how to employ it in proteins are extending the boundaries of cures for disease. science, including allowing researchers to The sparkle of marine bioluminescence understand, manipulate, and interact with occurs in species from fish in the deep the living brain,” says Pieribone. ocean to jellyfish and dinoflagellates in the When scientists develop methods shallows, among others. They create light that allow them to see things that were through the interaction of the enzymes once invisible, research takes a giant luciferase and luciferin (the terms are derived from the Latin word lucifer—light- Image of the bioluminescence of bringer), or by hosting light-emitting bacte- Chaetopterus, the parchment tubeworm. ria. Biofluorescence, sometimes confused Image credit: David Liittschwager, Scripps with bioluminescence, is released when Institution of Oceanography

8 Oceanography | Vol.32, No.4 The eels’ biofluorescence could be related to their unusual management of bilirubin, says Pieribone. Unlike other ver- tebrates, he says, the blood plasma of some eels, such as Anguilla japonica, is blue-green due to a high concentration of biliverdin, the precursor of bilirubin and the pigment responsible for the greenish color sometimes seen in bruises.

GROUND-TRUTHING CANCER IMMUNOTHERAPIES Bioluminescence is also leading to better ways of developing cancer immunother- An eel whose unique green fluorescence led to a patent. It was photo- apies. Researchers at the University of graphed near Little Cayman Island. Image credit: Jim Hellemn Southern California (USC)’s Keck School of Medicine created a bioluminescence test to find out whether an immuno- resents,” says Chaudhary. “That’s why the faster than ferritin in humans. The secret therapy is in fact killing the cancer cells inventions are named after local beaches.” may be in the worm’s light show, scien- that are its targets. The results of the Like the Matador assay, the Topanga tists have discovered. The study was study were published on January 9, 2018, assay uses luciferase to measure the funded by the Air Force Office of Scientific in Scientific Reports. expression of chimeric antigen recep- Research. Biologists there are interested “One of the most promising areas in can- tors on the surfaces of patients’ disease-​ in learning more about the bioluminescent cer research is immunotherapy, including fighting T cells. properties of this unusual worm and the CAR-T [chimeric antigen receptor-T] cells,” “Academic labs and biotech com- speed of its ferritin. says senior author Preet Chaudhary, a panies are developing CAR-T cells Tubeworms are common in muddy hematologist at USC. The gold standard directed against different cancers,” says nearshore habitats in temperate coastal for finding out whether immunotherapy is Chaudhary, “but a major challenge is the waters around the world. This tubeworm working, he says, has been an expensive lack of a fast, economical, sensitive assay has another unique ability: it can keep and complicated radioactive chromium for the detection of cancer-fighting CARs its bioluminescent blue light glowing for release assay. Now Chaudhary and col- on the surfaces of immune T cells.” hours—and sometimes days. That’s much leagues have developed an assay based The Topanga assay, he says, like the longer than most bioluminescent organ- on luciferase. Matador assay, can be employed in as isms, which usually “light up” for seconds The researchers used biolumines- little as half an hour. “It has major uses or even milliseconds. cent Pacific Ocean crustaceans for the not only in research on next-generation The worm’s bioluminescence may rely test, named the Matador assay after CAR-T cell therapies, but also on CAR-T on the iron dissolved in seawater. But it’s the El Matador State Beach in Malibu, cells that are in current clinical use.” more likely, researchers think, that the California. Luciferase from the creatures Chaudhary is planning studies to deter- worm’s mucus contains iron that regulates is introduced into cancer cells, then leaks mine whether the Topanga assay can its light production. Chaetopterus kept in out as the cells die, leaving a visible glow monitor the expansion and persistence seawater with no iron can still produce that can be measured. of CAR-T cells after they’ve been given mucus with strong luminescence. More The scientists tested the Matador to patients. That would allow doctors to research, marine scientists say, will lead to assay’s effectiveness in several cancers, identify people at risk of a toxic reaction new answers. including chronic myelogenous leuke- if the CAR-T cells expand too quickly, and In One Thousand and One Nights, story­ mia, acute myelogenous leukemia, and to find patients who might relapse if the teller Scheherazade spun a never-ending Burkitt’s lymphoma. The assay could accu- CAR-T cells die out too soon. tale. So, too, in the saga of 1,001 living rately recognize the death of a single can- lights, the sequel awaits. cer cell. “The Matador assay can detect THE SUPERPOWERS OF cell death in 30 minutes,” says Chaudhary. BIOLUMINESCENCE ABOUT THE AUTHOR “That will lead to faster treatments for Chaetopterus sp. It sounds like an alien Cheryl Lyn Dybas ([email protected]), a Fellow of the International League of Conservation patients receiving immunotherapies such being. In its own way, it is. Also known as Writers, is a contributing writer for Oceanography and as CAR-T cells.” the parchment tubeworm, its souped-up a marine ecologist and science writer. She also writes Chaudhary’s team recently developed a ferritin may be as linked with biolumines- about science and the environment for National Geographic, BioScience, Ocean Geographic, related assay based on bioluminescence, cence as spinach is with Popeye. Canadian Geographic, National Wildlife, Yankee, and called the Topanga assay after Topanga Ferritin is an important protein; it man- many other publications. Beach in Malibu. The researchers pub- ages iron metabolism in cells by storing lished their results in the February 13, 2019, and releasing it in a controlled way. ARTICLE CITATION issue of Scientific Reports. “The work is In this tubeworm, known for its biolu- Dybas, C.L. 2019. Bioluminescent, biofluorescent spe- cies light the way to new biomedical discoveries. inspired by and celebrates the beauty minescence, ferritin has the fastest per- Oceanography 32(4):8–9, https://doi.org/10.5670/ and endless possibilities the ocean rep- formance discovered, almost eight times oceanog.2019.403.

Oceanography | December 2019 9