Death is not a single event. It is a series of events as life fades away. Part of it happens to be rigor mortis – a period of stiffness, which makes body somewhat rigid as muscles contract and joints lose flexibility. For humans it occurs after the main event of heart stopping, but a dying worm experiences rigor mortis early in the death process. Scientists from UCL and Washington University say that it could reveal something about the process of death.
C. elegans experience rigor mortis while they are still alive – it is one of the early stages of death for them. Image credit: Peter Andrus via Wikimedia(CC BY-SA 4.0)
Organisms constructed from many cells are not homogenous in a way. These cells do not die all at the same time. Scientists struggle to understand the process of death and what causes cells to die after heart stops beating. They say that it is very important to understand the process of death better, because it might have implications in lethal diseases and ageing. Scientists studied a worm called C. elegans to discover the mechanisms involved when multicellular organisms die.
Death spreads through the process called cellular necrosis, when cell release calcium, triggering death of neighbouring cells. This process happens first in muscle, leading to muscle hypercontraction and rigor mortis, also known as stiffness of death. For humans rigor mortis happens after death and is followed by necrotic degeneration where the muscles become soft again. This is actually how most mammals die, which is important to meat industry – this is how meat becomes tenderer.
Rigor mortis is not only specific to humans and mammals – it happens to worms too. But scientists were surprised to see that rigor mortis in C. elegans occurs while they are still alive. That is because worms are small enough to get oxygen in a different way – they don’t die from circulatory failure. Instead these worms undergo something called a ‘belly punch’ – contraction in the head drives the pharynx backwards into the intestine.
Worms are good research subjects. We have a lot of them and they are easy to observe. Professor David Gems, the leader of the research team, said: “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. It helps us to understand death in humans, and perhaps in the future to prevent death in mortally ill patients”.
Understanding death is good for all of us. It is a completely natural phenomenon and it is not going to be avoided anytime soon. Understanding how death occurs could help making the end of life easier and could eventually help treating terminally ill people.
Source: UCL