Scientists observe rigor mortis in dying worms for the first time

Death is a process that eventually comes for all living things – but, just how the body succumbs is not the same for every organism.

In humans, a state known as rigor mortis sets in hours after passing, causing the body to stiffen up before ultimately relaxing again.

But for a species of roundworm, rigor mortis begins while the creature is still alive.

Scientists have captured footage of worms undergoing rigor mortis for the first time, uncovering new insight on the processes that occur as a multicellular organism dies – and, it could reveal clues on age-related death in humans.

In the footage, the researchers use blue fluorescence to highlight the passage, showing how death spreads from cell to cell ‘like a house burning down,’ said lead author Dr Evgeniy Galimov. The discovery could shed light on age-related death in humans

According to the researchers from University College London, the discovery marks the first time rigor mortis has been observed in worms.

While death may be defined as the moment the heart ceases to beat or the brain no longer functions, the processes involved may begin long before this.

‘Cell death has been widely studied but much less is known about death of whole organisms, how it happens, what triggers it, and when it begins and ends,’ says Professor David Gems, from UCL Institute of Healthy Ageing.

‘But it’s extremely important for understanding fatal disease in humans, especially those caused by aging.’

In C. elegans, the researchers observed how death spreads through the body in a process known as cellular necrosis.

Beginning the muscle, dying cells trigger the death of their neighbours by releasing calcium.

This leads to hypercontraction and rigor mortis.

Then, death spreads to the intestine.

Beginning the muscle, dying cells trigger the death of their neighbours by releasing calcium

In C. elegans, the researchers observed how death spreads through the body in a process known as cellular necrosis. Beginning the muscle, dying cells trigger the death of their neighbours by releasing calcium.

In humans, a state known as rigor mortis sets in hours after passing, causing the body to stiffen up before ultimately relaxing again. But for a species of roundworm, rigor mortis begins while the creature is still alive. Blue fluorescence tracked cellular necrosis, including rigor mortis

In humans, a state known as rigor mortis sets in hours after passing, causing the body to stiffen up before ultimately relaxing again. But for a species of roundworm, rigor mortis begins while the creature is still alive. Blue fluorescence tracked cellular necrosis, including rigor mortis

In the footage, the researchers use blue fluorescence to highlight the passage, showing how death spreads from cell to cell ‘like a house burning down,’ said lead author Dr Evgeniy Galimov.

According to the team, the rigor mortis seen in the worms is similar to that which occurs in humans, with muscle contraction followed by relaxation.

But, for C. elegans, it happens much earlier.

‘What really surprised us at first was that rigor mortis in worms begins while they are still alive,’ said Dr Galimov.

‘But then we realized that death from circulatory failure, as in mammals, doesn’t happen in C. elegans. The worms are so small they don’t need a circulatory system to get oxygen for respiration.’

WHAT DOES DYING FEEL LIKE?

Scientists reported in October 2017 that they had discovered a person’s consciousness continues to work after the body has stopped showing signs of life.

That means they may be aware of their own death and there is evidence to suggest someone who has died may even hear their own death being announced by medics.

A team from New York University Langone School of Medicine investigated the topic through twin studies in Europe and the US of people who have suffered cardiac arrest and ‘come back’ to life, in the largest study of its kind.

Study author Dr Sam Parnia told Live Science: ‘They’ll describe watching doctors and nurses working and they’ll describe having awareness of full conversations, of visual things that were going on, that would otherwise not be known to them.’

He said these recollections were then verified by medical and nursing staff who reported their patients, who were technically dead, could remember details of what they were saying.

Doctors define death based on when the heart no longer beats, which then immediately cuts off blood supply to the brain.

Once that happens, blood no longer circulates to the brain, which means brain function halts almost instantaneously.

You lose all your brain stem reflexes, including your gag reflex and your pupil reflex.

The brain’s cerebral cortex, which is responsible for thinking and processing information from the five senses, also instantly flatlines.

This means that within two to 20 seconds, no brainwaves will be detected on an electric monitor.

This sparks a chain reaction of cellular processes that will result in the death of brain cells. 

However this can take hours after the heart has stopped, researchers said.

The findings suggest old age decline is linked to cells’ weakening ability to generate energy in the form of ATP.

Without this energy, the cells can’t hold calcium in the muscle, 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 backwards 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.’



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