Aequorea victoria, the jellyfish that made rabbits glow green and revolutionised science, features in our list of the top ocean light-makers.
Sarah - my first critter is a type of jellyfish called Aequorea victoria, or the ‘crystal jelly’, found off the West Coast of North America and out into the Pacific ocean.
It’s a small jellyfish, growing up to around 10cm across, and is well named – it’s almost completely colourless, but does show luminescence in a ring around the bottom edge of the main body.
The protein that causes the greenish glow of the crystal jelly’s luminescence is known as GFP – the Green Fluorescent Protein. When the jelly is startled, its cells release calcium ions, that excite a blueish coloured protein called aequorin, which then stimulates the GFP to glow.
Osamu Shimomura first extracted GFP from the crystal jelly, and now it’s used in many other areas of biology – and particularly to stain cells for fluorescent microscopy. The good thing about GFP is that unlike most stains that are used, it’s not toxic to living cells, so it can be used to look at living tissues under the microscope. There’s also several mutations of the GFP protein that have been developed – Blue FP, Yellow FP, Cyan and actually, Red fluorescent proteins have been extracted from corals. These can each be attached to a different protein or structure in a cell to see how they interact.
There’s also been several transgenic animals produced by modifying their genes so they produce GFP – there’ve been mice, zebrafish (that you can buy in pet shops – that’d be quite cool to have glow in the dark fish in your tank at home), and even rabbits.
The crystal jellies have quite an interesting life cycle – they alternate between a sessile, or ground dwelling hydroid form, and the swimming medusa form. The medusae are either male or female and will release gametes into the water column, which meet and fertilise then settle onto the sea bed and grow into a hydroid colony. In the spring, the colonies then bud off more little medusae into the water column, that grown, start producing gametes, then die after about 6 months.
So they’re a really good example of how the oceans are helping to advance other areas of research – a key point to think about when we’re talking about conservation. This is a point made about the rainforests on land as well – the potential for new drugs etc in these untapped areas is a major reason to conserve species and ecosystems.
Part of the show Glittering seas: the science of ocean bioluminescence from the 11th Nov 2011