In the last post, we talked about the idea of organisms manipulating light. We saw a few examples of organisms reflecting/emitting light to change how other organisms perceive them. I wrote that “Every color we see in nature has a purpose and/or reason for being the color that it is”. So why are plants green? Why are we the color we are? And what do those colors mean for our lives? We will answer all those and more including… What is radiation? And Specifically what are gamma rays? Why should we care?
Today, when most of us think of energy, we think of electricity. But, energy exists as potential energy in objects under gravity or in a spring under pressure, and kinetic energy in objects that are in motion. Heat, light and radiation are also forms of energy. Thermal energy is the energy of heat, which originates from the rapid movements of particles within an object. Light and radiation have energy in the form of waves or particles. You can take a look at this short video which explains radiation in more detail.
Melanin
Almost all living things are adapting to radiation constantly. Fungi, bacteria and especially plants have mechanisms that react to the amount light that is available. A simple example is how plants have internal clocks, and change their metabolism during the night or during the day. An example of this in our species is tanning. When we tan our skin cells produce pigments that are broadly called melanin. UV radiation from sunlight is also connected to our mechanism for producing Vitamin D. Melanin is an antioxidant and an effective broadband UV ray absorbent. This concept is important for us, because it also exists in fungi found in radioactive areas, and it has been shown to have some exciting properties. See how Painted Turtles use it to go without oxygen for long periods!
Chlorophyll
There is a mechanism that was first thought to have evolved in cyanobacteria billions of years ago. It was such an effective use of resources that it’s thought to be the initial source of the oxygen that we breath today, which you can read more about here. That powerful mechanism is one of the many reasons life exists as we know of it. I am sure you haven’t already thought of it, this mechanism is photosynthesis. But the taxonomy of the word photosynthesis doesn’t really tell us much of what is going on. In short, plants and algae create pigments called chlorophyll. These pigment molecules become excited when exposed to visible light. This is the start of an electron transfer chain where the energy is transferred from cholorphyll to make adenosine triphosphate, or ATP, which is chemical energy that most organisms use. In a similar sense, melanin has recently been found to be photoreactive when subjected to different forms of electromagnetic radiation creating a flow of energy and ATP.
Cryptococcus neoformans
The mechanism of radiation absorption by melanin was discovered in one of Earth’s first irradiated disaster grounds: Chernobyl. The radioactive environment was exploited by a fungus called Cryptococcus neoformans (pictured above). These fungi can thrive in these environments, while others cannot. Hence, they are called radiotrophic. This is a mechanism we are really interested in considering hair coloration is due to melanin. It’s a class of compounds that a lot of organisms, including cats, are already able to produce. Melanin is responsible for both absorbing radiation, as well as pigmentation, in our hair and skin. Is there a way for us to leverage these special compounds for our color changing mechanism?
Living things adapt to thrive in their environments. When the environment is high energy radiation, we’ll be able to find living things that are able to survive using unique mechanisms. Events like Chernobyl are devastating and tragic, yet, new and unique living things have found niches in these radioactive areas.