Celebrating Juneteenth

On June 19, 1865, the Emancipation Proclamation was officially enforced in Texas, the last state where slavery remained legal. This came two and a half years after the proclamation had outlawed slavery in the Confederate states. Though Juneteenth has been celebrated for decades, it was only recognized as a federal holiday in 2021.

Racial justice was, and still is, a hard-fought battle. One aspect of this prejudice has been the erasure of African Americans’ inventions, discoveries, and ingenuity. By recognizing remarkable Black scientists, we attempt to highlight contributions that have too often been overlooked.

In keeping with our Bioluminescent June theme, we are spotlighting Dr. Emmett Chappelle. Dr. Chappelle pioneered the use of luciferase to detect ATP, a molecule present in all living cells. He would go on to apply this research to bacteria detection technologies that are still used in medical, environmental, and aerospace studies today.

Luciferase is a generic term for the class of oxidative enzymes that produce bioluminescence, and is usually distinguished from a photoprotein.

Dr. Chappelle began his work in bioluminescence research at the University of California, Berkeley, where he earned a B.S. in biochemistry. He later received an M.S. in biology from the University of Washington in 1954. His research focused on luciferase, an enzyme used by fireflies and other bioluminescent organisms to produce light.

By measuring the light produced in this reaction, scientists can detect the presence of living cells. This breakthrough opened the door to new methods of identifying bacterial life.

After continuing his studies at Stanford University, Dr. Chappelle joined the Research Institute for Advanced Studies in Baltimore, where his work contributed to the development of safe oxygen supplies for astronauts. He later joined NASA’s Goddard Space Flight Center, where he used his expertise in luminescence to develop methods for detecting bacterial life forms.

Working with Grace Picciolo, Dr. Chappelle helped develop techniques that have been used to monitor bacteria in waterways, diagnose bacterial infections, and support the search for life beyond Earth.

Dr. Chappelle has been honored as one of the top 100 African American scientists and engineers. His contributions laid the foundation for important advances in medicine, environmental science, and space exploration that continue to benefit us today.