Nitric oxide holds the key to firefly glow

LONDON The mysterious secret of how fireflies control when they glow is starting to be unravelled. A study published in 29 June Science, has discovered that the key chemical that fireflies need to switch on and off could be nitric oxide.

Scientists have known for some time that the spectacular lightshow put on by fireflies as part of their courting display starts from bursts of neural activity stimulating the release of the primary neurotransmitter, octopamine. This triggers the firefly's light producing organ in the abdomen, called the lantern, which contains thousands of photocytes subdivided into an inner region rich in organelles housing luceriferin and luciferase. These react to generate light when oxygen is available, which is provided by thousands of mitochondria packed along the photocyte edges.

But it remained unclear how this process was being switched on, as the firefly abdominal nerve endings are not in direct contact with the ...