Have you ever tasted Japanese Anguilla that is principally served as a sushi meal? Very appreciated in the high gastronomy and sometimes used as a cure in Chinese traditional medicine, the Japanese Anguilla (called Anguilla japonica – see caption image) is also very interesting for biologists. Indeed, scientists have discovered that the muscles of this animal produce a fluorescent protein called UnaG (or unighi), representing the first discovery of such a molecule in a vertebrate.
Fluorescent proteins are standard tools in bioimaging, used by cell and molecular biologists, as well as biochemists. These molecules don’t produce light but, when illuminated by external sources, they are able to shine. In 2008, the Nobel Price in Chemistry was awarded to three American and Japanese researchers for the discovery of the first fluorescent protein (also called GFP or green fluorescent protein – found in the medusa, some microbes and in corals – and for the development of different other fluorescent proteins, that allow to obtain multiple interesting phenomena in biology. In fact, these micro-lusters are generally used to localize and identify different compartments in the cell. Biologists employ them as “spy-molecules” to recognize other proteins and follow the expression of genes in a given cell system. The molecules can also be expressed homogeneously in the organism of a mutant mouse model: when the protein is illuminated, the animal shines like a stranger in the night.
Since their discovery, a variety of fluorescent molecules have been developed and researchers were then able to show their artistic talents by creating a rainbow for these proteins, which, are now used on a daily basis in the laboratory. With the discovery of the fluorescent molecule UnaG in the Japanese anguilla’s organism, the scientists were already able to highlight its fundamental properties: the molecule shines when attached to the Hemoglobin derivative, the Bilirubin, which quantity in the blood is measured to test an eventual liver disease or jaundiceIt also seems that the fluorescent molecule shines intensely when it is in a medium with a very low oxygen content, which makes it possible to use it to identify tumors or cancer cells that grow in anaerobic (low oxygen) medium.
On the menu of this season, I invite you to discover the exquisite taste of Japanese Anguilla served generally as a refreshing, but do not be surprised if in the dark, you discover a fluorescent sushi!
Kumagai et al (2013)A bilirubin-inducible fluorescent protein from eel muscle. Cell 153(7):1602-11.
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