Death – while the only constant in every living organism's life – also differs from organism to organism when it comes to how the body succumbs to it. But what exactly happens during the process of dying?
While humans are known to be struck by a phase called rigor mortis, where the body stiffens briefly after you die and then relaxes again, it turns out that in case of a species of roundworms, rigor mortis sets in while the creature is still alive.
Scientists have finally captured footage of rigor mortis occurring in these roundworms, which has been able to shed new light on the processes that a multi-cellular organism goes through upon dying. This could in turn also reveal clues about age-related death in humans.
Researchers from the University College London stated that this is the first time rigor-mortis has been observed in worms. While medically, death is defined as the moment the heart stops beating or the brain no longer functions, the processes involved with death set in long before this.
"Cell death has been widely studied but much less is known about the death of whole organisms, how it happens, what triggers it, and when it begins and ends," Professor David Gems, from UCL Institute of Healthy Ageing, who led the research, mentioned in the study. "But it's extremely important for understanding fatal disease in humans, especially those caused by aging."
The observations made by researchers on these c. elegans revealed that death spreads through the body via the process of cellular necrosis. Beginning with the muscles, these dying cells trigger the death of the ones next to them by releasing calcium. Eventually, death spreads to the intestine.
The findings also suggested that in deaths related to old age, the cause is mostly cells' weakening ability to generate energy in the form of the ATP enzyme. Without this energy, cells are unable to hold calcium within them, causing it to flood out and trigger necrosis.
"Dying C. elegans also undergo what we term a "belly punch" phenomenon where death contraction in the head drives the pharynx backward into the intestine, and the impact triggers cell death," said professor Gems.
"Discovering rigor mortis in worms is exciting as it highlights a key step in the chain of events leading from healthy adulthood to death from old age," Gems said.
"It helps us to understand death in humans, and perhaps in the future to prevent death in mortally ill patients."
The study was published in the journal Cell Reports.