The finding is remarkable because the blue light was observed both for worms dying from natural causes and for stress-related death, such as being under extreme heat or cold. Starting from one end of the worm, the blue light wave would propagate along its intestine until it was dead. This ordered propagation suggested that, among multicellular organisms, death may happen through a series of coordinated “self-destruct” signals.

Gems found that the blue light was caused by the activation of a biological pathway related to calcium signalling, ultimately triggering the fluorescence of small molecules called anthranilic acids (AAs). They found that the spark of blue light was not due to the sudden production of AAs, but because of their release from acidic cellular compartments when the membranes keeping them trapped broke open upon necrosis.

When the team blocked the calcium signalling pathway, the burst could be delayed if a stress was the cause of death. However, no delay could be obtained if it was a case of age-related death. This suggests that age-related death involves more than just calcium signalling.

The work casts doubt on the idea that age-related death is simply a consequence of accumulated damage at the cellular level. It may well be that a coordinated action decides when the threshold is met. But the fact that death can now be caught in action under a microscope will help us develop and understand methods to delay it. In which case, seeing the light might be a good thing in the end.

PLOS Biology, June 2013. DOI: 10.1371/journal.pbio.1001613 (About DOIs)

Luc Henry is postdoctoral fellow at the Swiss Federal Institute of Technology in Lausanne.

This article was first published on The Conversation.