New fluorescent protein from eel revolutionizes clinical biomarker

Researchers from the RIKEN Brain Science Institute (Wako City, Japan) have discovered that Unagi (Anguilla japonica), a Japanese freshwater eel, harbors a fluorescent protein that could serve as the basis for a new clinical test for bilirubin, a critical indicator of human liver function, hemolysis, and jaundice.1 The discovery also sheds light on the mysterious and endangered Unagi that could contribute to its conservation.

Related: Optogenetics shows that memories live in specific brain cells

Related: Chemical reagent, fluorescence microscopy team to produce mouse brain tissue details in 3-D

Drs. Atsushi Miyawaki and Akiko Kumagai and their team cloned a gene from Unagi for an unusual fluorescent protein they named UnaG, for Unagi Green protein, that allows eels to glow in the dark. UnaG is the first fluorescent protein found in vertebrates; previously, they were thought to exist only in simple animals like jellyfish.

But what makes UnaG truly unique in nature is that it needs a natural chemical to activate its powerful green light emission. In a surprise twist, the compound was identified by the authors to be bilirubin, a slippery molecule universally used in clinical labs around the world as a human blood marker for liver function.

Bilirubin is the breakdown product of blood hemoglobin and is toxic if present in excess in the body like in the characteristic yellow skin and eye color conditions seen in newborn babies, jaundice and kernicterus. It is also a common marker in blood tests where bilirubin is used by doctors to assess liver function and for the assessment of health, including hemolysis, the loss of red blood cells in anemia.  

By analyzing the structure of UnaG, the team discovered a novel mechanism of fluorescence-enabling bilirubin to bind to UnaG and activate its light emission. With this property, they developed a superior new assay for bilirubin with high sensitivity, accuracy, and speed that may become the global clinical standard, and can be used in developing countries where child liver health is a major issue.

Fluorescence image of a transverse section of a formalin-fixed eel
Fluorescence image of a transverse section of a formalin-fixed eel.

Japanese freshwater eels have a long-distance migration life cycle, growing in inland rivers and swimming far into the sea to spawn. The authors identified UnaG and bilirubin in the muscle cells of Japanese, American, and European eels where they may aid in endurance swimming during migration. The unexpected discovery of UnaG may initiate legislation to conserve endangered eel species.

“We believe that UnaG provides an unexpected foothold into several important but currently obscure areas of human health including bilirubin metabolism and muscle physiology during endurance exercise,” Miyawaki concludes. “Before the discovery of UnaG, I couldn’t imagine that basic science could have such a direct impact on human health. From a simple eel, we found a new path to the clinic.”

REFERENCE
1. A. Kumagai et al., “A Bilirubin-Inducible Fluorescent Protein from Eel Muscle,” Cell, doi:10.1016/j.cell.2013.05.038 (2013).

-----

Follow us on Twitter, 'like' us on Facebook, and join our group on LinkedIn

Subscribe now to BioOptics World magazine; it's free!

Get All the BioOptics World News Delivered to Your Inbox

Subscribe to BioOptics World Magazine or email newsletter today at no cost and receive the latest news and information.

 Subscribe Now
Related Articles

New bioimaging technique offers clear view of nervous system

Scientists at Ludwig-Maximilians University have developed a technique for turning the body of a deceased rodent entirely transparent, revealing the central nervous system in unprecedented clarity....

Fluorescent jellyfish proteins light up unconventional laser

Safer lasers to map your cells could soon be in the offing -- all thanks to the humble jellyfish. Conventional lasers, like the pointer you might use to entertain your cat, produce light by emittin...

Fluorescence microscopy helps provide new insight into how cancer cells metastasize

By using fluorescence microscopy, scientists have discovered an alternate theory on how some cancer cells metastasize.

In vivo imaging method visualizes bone-resorbing cell function in real time

In vivo imaging can visualize sites where osteoclasts (bone-resorbing cells) were in the process of resorbing bone.

BLOGS

Neuro15 exhibitors meet exacting demands: Part 2

Increasingly, neuroscientists are working with researchers in disciplines such as chemistry and p...

Why be free?

A successful career contributed to keeping OpticalRayTracer—an optical design software program—fr...

LASER Munich 2015 is bio-bent

LASER World of Photonics 2015 included the European Conferences on Biomedical Optics among its si...

White Papers

Understanding Optical Filters

Optical filters can be used to attenuate or enhance an image, transmit or reflect specific wavele...

How can I find the right digital camera for my microscopy application?

Nowadays, image processing is found in a wide range of optical microscopy applications. Examples ...

CONNECT WITH US

            

Twitter- BioOptics World

Copyright © 2007-2016. PennWell Corporation, Tulsa, OK. All Rights Reserved.PRIVACY POLICY | TERMS AND CONDITIONS