Issue 37

The Brilliant World of Bioluminescence

Bioluminescence is the production and emission of light by living organisms such as jellyfish, fireflies, and even some species of mushroom. The potential scientific applications of this “living light” could revolutionise the world as we know it, from medical research to glowing lollipops.

In 1832, on board The Beagle off the coast of Tenerife, Charles Darwin wrote in his notebook:

The sea was luminous in specks and in the wake of the vessel, of a uniform slightly milky colour. When the water was put into a bottle, it gave out sparks…

bioluminescent plankton in the sea

What he was seeing was a species of bioluminescent plankton which emits light when it is physically disturbed. The flashes of light are designed to startle predators and have the added effect of giving away the position of the predators to any higher predators. There are many examples of bioluminescence in the sea and it is estimated that more than 75% of deep sea animals produce their own light.

There are several reasons animals have evolved this ability including:

  • camouflage (a squid can blend into the night sky when viewed from below)
  • warning (some firefly larvae use bioluminescence to warn off predators)
  • mimicry (the anglerfish uses its bioluminescent lure to attract prey).

Humans have been utilising bioluminescence for many years. Fireflies were captured and used by miners to light their way underground, and indigenous tribes have long known how to navigate the jungle at night using the light emitted from bioluminescent fungi.

fireflies in a forest

In recent years, the way we make use of bioluminescence has become much more sophisticated. Levels of unwanted chemicals in water can be measured using the bioluminescence in a bacteria called Aliivibrio fischeri. The light produced by the bacteria is dimmer when there are pollutants present because the pollutants affect the growth and reproduction of the bacteria. There are several companies that are producing light up lollipops and cosmetics.

Researchers are currently investigating the potential of bioluminescence in green energy. Glowing plants have been produced using genes taken from fireflies and, more recently, mushrooms. It’s theoretically possible that, by engineering plants to produce light, we could have glowing plants in our homes, self-illuminating Christmas trees, and even light our streets using bioluminescent trees. These advances are still a way off and scientists are working on making the plants glow brighter.

FACT:

The light-producing chemical reaction involves a light-emitting pigment called luciferin, being acted upon by an enzyme called luciferase. This results in light energy being emitted. Bioluminescence has evolved separately, on land and sea, over 40 times. It is much rarer on land but can still be found in some species of mushroom and bacteria, and in some insects. Bioluminescence does not occur naturally in plants.

A potentially significant use of bioluminescence is in agriculture. Engineering plants that can alert farmers when they need water or nutrients via a bioluminescent-based system is the subject of current research. This approach could also produce plants that give early warning signs about disease or pest infestations, allowing farmers to act quickly and reduce crop waste. Bioluminescence genes might be linked to highlighting when a plant is perfectly ripe as well as when a plant is exhibiting stress, for example when it is diseased or not receiving adequate nutrition. The idea of ‘smart crops’ such as these has received a lot of media attention.

In 2000 a biologist from Cambridge University engineered a fluorescent potato that glowed under UV light when it needed watering. This would avoid over-watering and increase the potential crop yield. Research of this kind tends to meet a lot of opposition. People are very wary of genetically modified organisms (GMOs) and, if these approaches are to be widely adopted, more research needs to be done into the potential safety issues associated with them.

The use of bioluminescence in medicine is the subject of a lot of ground breaking research that is producing and improving both diagnosis and treatments for many conditions.

Before research was done on bioluminescence, work was already being done on fluorescence. Fluorescence is unlike bioluminescence in that the protein needs to be excited by blue light before emitting light of its own. The 2008 Nobel Prize in Chemistry was awarded for the discovery and development of Green Fluorescent Protein (GFP). GFP is found naturally in the crystal jellyfish Aequorea victoria. Since its discovery, GFP has been genetically inserted into many different cell types and various animals to shed light on important aspects of cell biology and disease dynamics. Researchers have developed genetically encoded fluorescent markers which enables colour coding of proteins and allows the study of protein interactions.

crystal jellyfish ‘glowing’ in the sea

Immunoassays, gene expression assays, drug screening, bioluminescent imaging, cancer research studies and investigations into infectious diseases have all been enhanced using bioluminescence.

The evolutionary process that resulted in bioluminescence may have taken millions of years, but its scientific applications continue to benefit many aspects of our lives and will continue to do so.

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WRITTEN BY

Dr Danielle Taylor
STEM Learning


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