Red-glowing railroad worm may hold key to better medical imaging

Many animals have the ability to emit light, but the most studied emit yellow-green light. An exception is the railroad worm, the larva of the Phrixothrix hirtus beetle, which emits both red and yellow-green light. It has a row of light-emitting organs along its body, giving rise to an effect like the lights of an illuminated train carriage, hence the name. An article in Scientific Reports details research by engineers and biologists at the Federal University of Sao Carlos and the University of electro-Communications in Tokyo to determine the mechanism of the red light emission.

The Brazilian team, attached to the country’s National Energy and Materials Research Centre, built on previous research by principal investigator Vadim Viviani which showed that luciferase, an enzyme involved in the production of light by invertebrates, when taken from fireflies changed the colour of the light they emitted from green to red in a test tube in response to the acidity of the medium in which the light-emitting reaction took place. However, they still did not know how the railroad worm naturally emitted red light. This effect is confined to a cell on the larva’s head, producing a light which the larva uses to find its way in the dark (the row of yellow lights along its side frighten away predators).