A group of biologists headed Prof Taifo Mahmud of Oregon State University has discovered that zebrafish (Danio rerio) are able to synthesize a chemical called gadusol that protects against ultraviolet (UV) radiation.
The zebrafish (Danio rerio). Image credit: Bernat Arlandis / CC BY-SA 2.0.
“The fact that the compound is produced by fish, as well as by other animals including birds, makes it a safe prospect to ingest in pill form,” Prof Mahmud said.
Gadusol was originally identified in cod roe and has since been discovered in the eyes of the mantis shrimp, sea urchin eggs, sponges, and in the dormant eggs and newly hatched larvae of brine shrimps.
It was previously thought that fish can only acquire the chemical through their diet or through a symbiotic relationship with bacteria.
Marine organisms in the upper ocean and on reefs are subject to intense and often unrelenting sunlight.
Gadusol and related compounds are of great scientific interest for their ability to protect against DNA damage from UV rays. There is evidence that amphibians, reptiles, and birds can also produce gadusol, while the genetic machinery is lacking in humans and other mammals.
Prof Mahmud and his colleagues were investigating compounds similar to gadusol that are used to treat diabetes and fungal infections. It was believed that the biosynthetic enzyme common to all of them, EEVS, was only present in bacteria.
They were surprised to discover that fish and other vertebrates contain similar genes to those that code for EEVS.
Curious about their function in animals, they expressed the zebrafish gene in Escherichia coli and analysis suggested that fish combine EEVS with another protein, whose production may be induced by light, to produce gadusol.
To check that this combination is really sufficient, the scientists transferred the genes to yeast and set them to work to see what they would create.
This confirmed the production of gadusol. Its successful production in yeast provides a viable route to commercialization.
As well as providing UV protection, gadusol may also play a role in stress responses, in embryonic development, and as an antioxidant.
“In the future it may be possible to use yeast to produce large quantities of this natural compound for sunscreen pills and lotions, as well as for other cosmetics sold at your local supermarket or pharmacy,” said Prof Mahmud, who is the senior author of the paper published in the journal eLife.
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Andrew R Osborn et al. De novo synthesis of a sunscreen compound in vertebrates. eLife 2015, 4: e05919; doi: 10.7554/eLife.05919
