‘Zombie genes’ come alive and grow larger with arm-like appendages in the brain for many HOURS after a person dies, study reveals
- Experts observed genes in brain tissue increase activity after a person was dead
- The team says these ‘zombie genes’ are inflammatory cells called glial cells
- They grew larger and sprouted long-arm like appendages for many hours
Most research suggests that everything in the brain stops once a person is declared dead, but a new study reveals some genes come alive shortly after.
A team from the University of Illinois Chicago (UIC) found these ‘zombie genes,’ which are inflammatory cells called glial cells, increase activity and grow to gargantuan proportions.
Researchers observed the actions in gene expressions in fresh brain tissue and observed them sprout long-arm like appendages for many hours after death.
Although seeing genes come alive post-mortem may sound bizarre, experts say it is not a complete surprise because these cells are tasked with cleaning ‘things up after brain injuries like oxygen deprivation or stroke.’
Researchers found these ‘zombie’ genes, which are inflammatory cells called glial cells, increase activity and grow to gargantuan proportions that sprout arm-like appendages for many hours after death
Dr. Jeffrey Loeb, the John S. Garvin Professor and head of neurology and rehabilitation at the UIC College of Medicine, said: ‘Most studies assume that everything in the brain stops when the heart stops beating, but this is not so.
‘Our findings will be needed to interpret research on human brain tissues. We just haven’t quantified these changes until now.’
The study analyzed fresh brain tissue collected during a standard brain surgery of an individual with a neurological disorder.
The team found that about 80 percent of the genes analyzed remained relatively stable for 24 hours — their expression didn’t change much.
Although seeing genes come alive post-mortem may sound bizarre, experts say it is not a complete surprise because these cells are tasked with cleaning ‘things up after brain injuries like oxygen deprivation or stroke’
The set of genes found to waken were those that provide basic cellular functions and are commonly used in research studies to show the quality of the tissue – also known as housekeeping genes.
What happens to the body when you die?
First your heart stomps pumping, so the flow of blood around your body stops.
This causes the blood to coagulate, forming clots and becoming thick and lumping.
Your muscles then stiffen in a process known as rigor mortis, which also stops you breathing and means no oxygen gets to your cells.
Your cells thus too begin to die, releasing enzymes that make your body very welcoming to bacteria and fungi.
These decompose and petrify your body and ultimately, within a year or so, most of the flesh on your body will have decomposed leaving just your bones behind.
Another group, known to be present in neurons and shown to be intricately involved in human brain activity such as memory, thinking and seizure activity, rapidly degraded in the hours after death.
These genes are important to researchers studying disorders like schizophrenia and Alzheimer’s disease, Loeb said.
A third group of genes — the ‘zombie genes’ — increased their activity at the same time the neuronal genes were ramping down. The pattern of post-mortem changes peaked at about 12 hours.
‘Our findings don’t mean that we should throw away human tissue research programs, it just means that researchers need to take into account these genetic and cellular changes, and reduce the post-mortem interval as much as possible to reduce the magnitude of these changes,’ Loeb said.
‘The good news from our findings is that we now know which genes and cell types are stable, which degrade, and which increase over time so that results from postmortem brain studies can be better understood.’
A previous study in 2016 found similar results in animals that showed more than 1,000 genes are active post-mortem, some of which only grind into gear 24 hours after the event.
Researchers at the University of Washington turned to two model lab animals, mice and zebra fish, to look for the tell-tale signs of genetic activity.
Analyzing the mRNA from the deceased mice and zebra fish, the team found evidence of activity in 1,063 genes.
The ‘zombie genes’ increased their activity at the same time the neuronal genes were ramping down. The pattern of post-mortem changes peaked at about 12 hours.
In a series of two studies published online in biorxiv in 2016, they report that the majority of the genes kick into action half an hour after the animals die, but some only seemed to ramp up after 24 or even 48 hours.
For both animals, more than half of the active genes coded for proteins, while the others were regulatory genes – which show significant energy is still being used to keep the system orderly.