Consider the Firefly...

I spent the first 14 years of my life in Southeastern New Mexico: dry desert country. Our summer vacations, however, were spent in southern Missouri where my grandparents lived. We loved it there. Moisture, rivers, grass, forests: it was heaven to me and my siblings and is why I live in the Ozarks today. It was during those vacations we first encountered fireflies: those magical flying lanterns! Ever the scientist, even at 14, I was fascinated that a small insect could produce light. How could it do that and not get hot like a light bulb? Fast forward to 1981. I'm a graduate student at the University of South Alabama College of Medicine and starting work on a doctoral thesis. One of the first things I learn is how to determine the activity of an enzyme known as phosphodiesterase or PDE. The assay used an extract of firefly lanterns (containing luciferin and the enzyme luciferase) to produce a small amount of light that was then measured with a luminometer. Combining the luciferin-luciferase extract with ATP (the energy source for many cellular functions) and the PDE enzyme resulted in obtaining PDE activity by measuring the amount of light produced from the firefly lantern extract. On a historical note, the extract was obtained from Sigma Chemical company in Saint Louis, MO. It was one of the first products made by the company back in the 1940's. People, including children, were paid to collect the fireflies from Forest Park near the Central West End of Saint Louis. Even today, Sigma will pay about a penny per firefly! As a child I didn't imagine ever finding out how fireflies worked. As an adult, I sit on my deck in the summer evenings and watch the flying lights. I know how they light up now. But the wonder remains.