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Why do fish need sunscreen? [Coffee-byte]

Danio rerio, better known as the zebrafish
Danio rerio, better known as the zebrafish (Photo credit: Wikipedia)
If you remember your last trip to the beach and try to list out the things you took for this trip, chances are that the sun block or sunscreen will feature in there. Why just the beach, using a sun screen is almost a part of our daily routine, whenever we know we will be spending time under the sun. But, as you might have noticed, it is only humans who wear a sun block while the rest of creatures walk, swim and fly on the planet, unprotected. As much as we, humans, like to think that we are the smartest on the planet, we actually are not. The fact is that we have to manufacture our sun blocks in factories, whereas fishes can do it on their own. Why just adult fishes, even fish eggs can do this nifty trick that protects them from harmful sunrays.

Research conducted at the Oregon State University, shows that zebrafish can produce this magic chemical called gadusol, that can protect it from UV-B rays of the sun. Before this research was published, it was believed that fishes take up gadusol from the bacteria and algae that they consume as food and stock it for their own use. But then the questions arises, why would a fish produce a sun block. Before, we I give you the answer, let me tell you that the genes responsible for producing gadusol, named EEVS and MT-Ox are found not only in zebrafish but also in amphibians, reptiles and birds. So, in a way, most animals on the planet can produce their sun block. So, a better question would be, why are all these animals doing this?

More than a sun block

Gadusol is more than just a sun block. It has properties of an anti-oxidant that can help in combating stress and plays a role in embryonic development too, hence the presence in embryonic cells. Scientists are also looking at compounds that are similar to gadusol and could potentially be used to tackle diabetes and fungal infections.

Researchers were able to transfer zebrafish genes into a strain of yeast and produce gadusol in the lab. In the future, this modified yeast could be used to make sun blocks in large quantities and since the product is naturally formed and found, the next generation sub blocks, could even be ingested without any harm.

But its not just the sub block that we are bothered about. Life under the sea hold vital clues to longevity and prevention of cancer too. I can only hope that we unearth these secrets soon.


Osborn AR, Almabruk KH, Holzwarth G, Asamizu S, LaDu J, Kean KM, Karplus PA, Tanguay RL, Bakalinsky AT, & Mahmud T (2015). De novo synthesis of a sunscreen compound in vertebrates. eLife, 4 PMID: 25965179


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