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BIOLUMINESCENCE: FIREFLIES AND THE FUTURE Light is such a powerful force in our universe and the idea of an organism being able to create its own light is an incredibly exciting concept. How are they able to create this "light"? And why is it useful for their survival? Fireflies must utilize this fairly unique ability for some important purpose. Could these light-producing fireflies teach us anything about life? Why Do Fireflies Glow? Organisms that produce light are referred to bioluminescent beings. Bioluminescence is defined as "the process wherein light is produced by a chemical reaction which originates in the organism". Bioluminescence is mostly a phenomenon found at the bottom of the ocean floor, but fireflies also possess this ability. They emit a soft light and are often called "lightning bugs" because of the way they flash their light on and off. Contrary to what one might think, the glow that the fireflies give off is not used to attract or deter their prey. On the other hand, fireflies use different intermittent signals in order to capture the attention of a possible future mate. Both sexes of fireflies use a specific flash pattern that can range anywhere from a short burst to a long continuous flashing sequence. Within any given population, there are many different species of fireflies and each species has a distinct signal. Males and females locate each other by recognizing their specific sequences. Since mating is essential to survival, attracting a mate can sometime become an aggressive game. It is not unusual in this game for a specific female species of firefly to fake their signals in order to confuse and lure a male from another species for the sole purpose of eliminating him. Overall, the firefly's lantern is essentially a courtship device; but how does the firefly actually make light? How Does Bioluminescence Work? The light that a firefly creates is the result of a combination of four different ingredients. This light is produced through a chemical reaction involving Luciferin, which is a substrate, Luciferase, an enzyme, ATP, and oxygen (3). The light producing section of the body is located in the sixth or seventh abdominal section of the firefly. It is within this cavity that the two compounds Luciferin and Luciferase are stored. A firefly will draw oxygen in through its complex system of air tubes and expose the oxygen to the Luciferin and the Luciferin will then oxidize and activate the Luciferase. This will generate a light that will shine through the skeleton of the abdomen. It is important to note that scientists disagree about the method that the fireflies use to control the duration of their flashes. One theory, known as the "Oxygen Control Theory", explains that fireflies can control the length and duration of their light by regulating the amount of oxygen that they intake. If little or no oxygen reaches the part of the firefly known as the phonic organ, the chemical reaction will not be extremely strong and the light of the firefly will not shine very brightly or for a lengthy duration. Another theory, known as the "Neural Activation Theory" states that fireflies have neural control over the activity of structures called "tracheal end cells". These structures aid in the initiation of the chemical reaction. Whether or not the fireflies have physical or neural control over their ability to produce light, their method of creating the light that emanates from their bodies is extremely efficient. Very little heat is given off of this light which means that not very much energy is wasted at all. This "cold light" has a 96% efficiency rating; which, when compared to an incandescent light that has only 10% efficiency, is rather impressive. How Useful is Bioluminescence? Christopher Contag, a bioluminescence researcher a Stanford University began to think more about this glow-in-the-dark idea and developed a way to utilize the process that occurs in fireflies when doing research about living tissue. This is because fireflies create light due to a chemical reaction that depends on the presence of ATP. If ATP is present in a sample of something, that is a good indication that life is occurring within that specimen. NASA has considered using this method to test for life on other planets. If these firefly compounds were mixed with samples and they produced a glowing reaction, that would mean that the presence of ATP would be highly likely. Biologists are also using this approach to fight Tuberculosis. If the enzyme Luciferase is added to a cultured sample of Tuberculosis and an antibiotic is also added, the strength of the antibiotic can be tested. If the drug fails, then the bacteria will continue to thrive and glow. This method enables researches and doctors to cut the time needed for drug treatments to just three days instead of three months. This research has also been employed in gene activation therapy cases, where ultraviolet cameras seek out genes treated with Luciferase. If light is visible, this means that the Luciferase gene is active. This will help researchers to know when they have made a successfully attempt a gene therapy. "This is a powerful approach for looking at any number of biological phenomena, because you can study gene regulation in a living animal over time, in superficial or deep tissues," said Contag. There is enormous potential for this type of research. There are many forms of life in this world. There is also an incredible range of diversity among the kinds of living organisms that roam the earth. Although there is still a lot that we do not know about bioluminescence and fireflies, we do know that the findings of the experiments with Luciferin, Luciferase, and ATP can lead scientists to new and exciting discoveries.