Shining the Light on Fungi, Crimes and Superheroes

If you were a superhero what power would you like to have- being able to fly, read other people’s minds, have an enormous strength? Or perhaps glow in the dark? Ok, the latter one may sound a bit useless. Unless there’s a permanent power outage, why would anyone want to glow in the dark? Since, however, we do not live in the world of the superheroes and we are creatures governed by the laws of physics and an outcome of evolution by natural selection, we perhaps should reconsider the “usefulness” of glowing in the dark.

Firefly forest
Firefly forest

Bioluminescence is a term used to describe emission of light by the living organisms. Perhaps the most commonly cited example of a bioluminescent creature is a firefly, but the fireflies are far from being an exception. Bioluminescence has independently evolved multiple times during the course of evolution, in fact, over 700 metazoan (multicellular organism) genera are known to be bioluminescent, not to speak of the numbers among the bacteria. The observable widespread of the bioluminescence across the different kingdoms of life clearly suggests that it may be quite a useful superpower to have.

Indeed living creatures have come up with some ingenious ways of using bioluminescence for their own advantage. Perhaps one of the best studies examples of bioluminescence is in Hawaiian bobtail squid and Vibrio fischeri , a symbiotic bacterium that colonises it. The squid has an organ on its belly-side where the bacteria reside. During the night, when the squid goes out for a hunt, the bacteria emit light that counter-illuminates the light coming from the moon and stars. The counter-illumination essentially erases the squid’s silhouette and acts as an invisibility cloak. The clock allows the squid to sneak up on it’s bottom dwelling prey unnoticed.

The Hawaiian bobtail squid has symbiotic bacteria, Vibrio fischeri, that provides bioluminescence
The Hawaiian bobtail squid has symbiotic bacteria, Vibrio fischeri, that provides bioluminescence

Bioluminescence is not, however, only useful for hiding, in fact, in many cases it is used for the opposite purpose- to attract. Fireflies produce flashing light to attract the mating partners, many deep-sea fishes use bioluminescence to attract the prey. There are around 80 species of bioluminescent fungi worldwide. A well-studied species of fungus, N. gardneri, produces one of the brightest green bioluminescence among all of the known fungi. The amount of bioluminescence that the N. gardneri makes varies throughout the day, it peaks in the middle of the night, and is linked to the fungal circadian rhythms (the discovery of circadian rhythms won the Nobel Prize this year). It turns out that during the night-time the green light attracts the insects that are capable of spreading the fungal spores. This is essentially the same effect as a street lamp, which, as you may noticed, usually has a lot of insects flying around it during the night. Some spiders actually exploit the bioluminescent fungal light and make home next to the fungus, so that they would have a greater chance of catching an insect to eat.

Bioluminescent N. gardneri
Bioluminescent N. gardneri

On a chemical basis, bioluminescence is a reaction that involves three components: luciferase, luciferin and oxygen. Luciferase is an enzyme that in the presence of oxygen can oxidise the luciferin into a high-energy state. As the oxidised luciferin falls from high to low-energy state it releases photons of light that we see. Understanding of the chemical basis of the bioluminescence has been very useful in a number of laboratory settings. Scientists often use bioluminescent reactions as indirect measures for gene expression, the effectiveness of drugs, and imaging inside the cells or animals. In the popular media bioluminescence has often appeared in the form of a luminol reaction. Think the CSI or other detective-type series and that blue-light patches in a crime scene is a consequence of the high-state luciferin-like intermediate luminol. When luminol comes into contact with iron that is present in the blood, in the presence of several other compounds, it emits light. That is how the traces of blood can be detected (dilutions of blood of up to 1 part per million can be identified this way).

So, yes, while being a glow-in-the-dark person may not be the most attractive superpower it sure can come to use in nature. I am no expert in comic book superheroes but I did found one who has a bioluminescent superpower- Olivia Underwood, also known as Foxfire. Foxfire can emit light through her fingertips and as Marvel’s Database says:

Olivia Underwood, the Foxfire
Olivia Underwood, the Foxfire

Underwood had the power to project bioluminescent energy that weakened the molecular binding of matter, causing it to disintegrate. Her powers worked on both animate and inanimate objects. She was also able to use her bioluminescent energy to temporarily blind someone by projecting it around their eyes without disintegrating them.

Sadly, the Foxfire seems to be on the side of the members of the criminal Institute of Evil. Her name, Foxfire, actually comes from a name of a bioluminescent fungus which has been referenced by many figures well-known figures including the Aristotle and Mark Twain.

 

References:

Widder, Edith A. “Bioluminescence in the ocean: origins of biological, chemical, and ecological diversity.” Science 328.5979 (2010): 704-708.

Oliveira, Anderson G., et al. “Circadian control sheds light on fungal bioluminescence.” Current Biology 25.7 (2015): 964-968.

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