Lichens 'a natural sunblock'

Lichens 'a natural sunblock'

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Science Lichens_L
Photo: Bloomberg
When people talk about Antarctica, they usually think of penguins, whales and seals. But its plant life should not be overlooked.

Scientists can learn a lot from its vegetation, which survives in very low levels of humidity and high levels of solar radiation.

The Earth's ozone layer protects most of its plant life by absorbing harmful solar radiation. In areas such as Antarctica, where the ozone layer is getting thinner, UV-B radiation is reaching the land; UV-B radiation can destroy DNA, membrane lipids, proteins and other cellular levels in plants.

Yet one plant, a lichen - a combination of a fungus and alga that grows on rocks and trees - thrives in the harsh conditions of Antarctica; scientists have found 350 species of lichens there.

So what allows lichens to survive? The answer is in the way UV-B radiation influences the natural production of protective screening pigments called parietin, melanin and usnic acid. These compounds can absorb some UV-B radiation.

Scientists have found special compounds in Antarctic lichens that produce antioxidant activity. These compounds can prevent cell damage - and not only help lichens to survive, but also shows how natural pigments can be used for UV-filtering, and in antioxidant activities of skincare products, such as sunblock lotion.

This month I've got the chance to go and study lichens in Antarctica on an expedition with City University.

I will share my experiences after I return next month.

Question:

How do lichens survive in the harsh conditions of Antarctica?

Answer the question about this story and win fabulous prizes. E-mail your answer, your school name and phone number to yp@scmp.com with "Science" in the subject line.


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