Glow in the dark corals

11 July 2017

Interview with

Joerg Wiedenmann, University of Southampton

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Not content with just hearing about the amazing glow in the dark corals, we sent Tom Crawford along to Jorg Wiedenmann's exhibit at the Royal Society Summer Exhibition to check them out...

Tom - Jörg has brought me inside a very darkly lit room and he’s holding I think a UV flashlight.

Jörg - It’s blue light. So it’s 450 nanometres.

Tom - Okay, so he’s got a blue flashlight which is shining on a mini fish tank or a little puddling pool filled with about 10 centimetres of water, and there's all kinds of glowing creatures, and like rocks. Are these corals I'm looking at?

Jörg - No. what you're looking here sea anemones and they're actually our local stars, so they come from the Dorset Coast, they come from Cambridge Bay, and also from the Isle of Wight. You can see two different species here. So you have for the green tentacles here, the snakelock anemones, and here, the strawberry anemone. So the strawberry anemone would be usually red with green dots. We see here only the green dots because they contain one of this fluorescent protein pigments.

Tom - Do you have any actual corals for me to look at?

Jörg - Sure, we do, if you want to move over here. in this other tank, we have our tropical corals here. they are kept at higher temperature. You have a range of species from different parts of the world from the Great Barrier Reef, from the Caribbean, and also, from Fiji. So you can see here if we just shine the torch through the tank that there's a huge diversity of colours. We have these greens and yellow stones, and then you have various shades of red. If you also look down here, this is a typical shallow water coral and in these shallow water corals, the animal uses the fluorescent pigments to shield the symbiotic algae that live inside of the tissue from excess sunlight.

Tom - So when you say animal, the coral itself is an animal.

Jörg - Yes, the coral indeed is an animal. It belongs to the same group as the jelly fish and the sea anemones. In the case of the corals, you have many polyps that form a colony. They're attached to each other and they form a limestone skeleton on which they sit, so they're rather hard and brittle in contrast to the sea anemones or jelly fish which are quite squishy.

Tom - If a coral is an animal then, how do they feed?

Jörg - So you can see here the colonies of different shapes. In this particular colony, you have rather large polyps. One of the polyps is like 5 centimetres in diameter so they're really unusually big and you can also see that around the mouth that they are extending some tentacles. So they are behaving like a colony of sea anemones and they have this stinging cells with which they can capture prey items such as tiny crustaceans or little fish, and they feed on them.

Tom - Of course, corals are often used to demonstrate the effect – human impact on the environment and climate change it’s having because they seem to be very sensitive to changes in their environment. And beyond the fact that they're very beautiful creatures, is there a real reason why we need to make sure we look after these species?

Jörg - Yes, certainly. So you need to bear in mind, coral reefs provide a source of income for about half a billion of people in the world. Here, you have some very vivid examples. So these pigments can be used in biomedical research for example to understand how diseased cells work, you can use them to understand how cancer cells function, and the pharmaceutical industry can use them to develop tests which they can use to screen for novel drugs.

Tom - So it’s the case of taking the fluorescent pigment out of the coral. So like here, when you're shining the blue light, these things, they're really bright. They are glowing in the dark pretty and you're saying, we can take this pigment and then put it in a cell that is of interest in a human body, and then be able to track that and follow it.

Jörg - Yes, exactly that’s what we can do. Here, the pigments are encoded by the DNA so this is a very special case that you have a single pigment that is encoded by a single gene. So you can take this gene and can transfer it in a cell under study and you can use this genetic information to label proteins of interest in living cell systems.

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