Major Discovery: How Mitochondria ‘Meddle’ and Change DNA – This Is How the Human Species Evolves

Scientists in Britain have discovered that although it occurs rarely – in one child in 4,000 births – a part of the genetic code from mitochondria, the energy “batteries” of our cells, it enters human DNA altering it to some degree. The unexpected discovery essentially brings to light a new way humans evolve.

Researchers from the University of Cambridge and Queen Mary, London, led by the former’s Professor Patrick Chinnery, who made the relevant publication in the journal “Nature”, also found that mitochondrial DNA appears in some cancer cells, possibly causing cancer itself. cancer.

The tiny mitochondria inside human cells provide them with energy in the form of the ATP molecule. Each mitochondrion has its own genetic material – mitochondrial DNA – which is distinct from the rest of the human genome, which is made up of nuclear DNA (the genetic code inside the cell’s nucleus).

Mitochondrial DNA is inherited in children only from their mothers and not from their fathers, as is the case with nuclear DNA that comes from both parents. An American study in 2018 presented evidence for the first time that some mitochondrial DNA can also be passed through the paternal line, but this was met with great disbelief by the scientific community.

To investigate this claim, British scientists analyzed DNA from 11,000 families. What they found was that mitochondrial DNA rarely pokes through nuclear DNA, so they thought the American researchers had probably jumped to the wrong conclusion: what they observed was not mitochondrial DNA that had been passed down to the child from the father, but that had inserted itself into the nuclear DNA of some children.

A further study by the same British scientific team of more than 66,000 people found that this “invasion” of mitochondrial DNA into the nucleus occurs more often than expected, thus pointing to a new way of enriching and evolving the human genome.

As said by Dr. Chinery“billions of years ago a primitive animal cell absorbed a bacterium, which eventually became what we now call a mitochondrion. These provide energy to the cell allowing it to function smoothly, while also removing oxygen that is toxic at high levels. As it passes through time, pieces of these primordial mitochondria passed into the cell’s nucleus, allowing their (mitochondrial and nuclear) genomes to ‘talk’ to each other.All of this was thought to have happened long ago, before we even existed as a human species, but this “What we discovered is that this is not true. We can see this happening even at this very moment, as parts of the mitochondrial genetic code are transferred to the nuclear genome in a way that can be recorded.”

The researchers estimated that mitochondrial DNA is transferred to nuclear DNA at a rate of one birth per 4,000. If that same person later has children of his own, he will pass on to them the changes he has made to the mitochondrial and nuclear DNA. The study found that most people carry at least five such mitochondrial changes in their genome, while one in seven (14%) carry very recent changes of mitochondrial origin. The introduction of mitochondrial DNA into nuclear genome it can sometimes lead to very rare conditions, including a rare form of cancer of genetic origin.

It is not yet clear exactly how mitochondrial DNA “punches” into the nucleus, whether for example it does so directly or indirectly (eg via RNA). The researchers consider it possible that its penetration takes place inside the mother’s eggs.

Furthermore, the study of genetic samples from 12,500 cancer tumors found that mitochondrial DNA is even more common in cancer DNA, in about one in a thousand cancers. In some cases, it is the invading mitochondrial DNA that causes the cancer itself.

“Our nuclear genetic code gets damaged and repaired all the time. Mitochondrial DNA seems to act as a ‘band-aid’ to help the nuclear genetic code repair itself. Sometimes this is successful, but in rare cases it can make things worse or even trigger tumor growth,” Chinery said.

The researchers investigated whether the reverse occurs, ie mitochondrial DNA absorbs parts of the nuclear DNA, but found no evidence of this.

RES-EMP

Read the News today and get the latest news.
Follow Skai.gr on Google News and be the first to know all the news.