The human genome is littered with sequences left behind from long-ago viral infections but now scientists have found the code is still active.
Ancient viruses were critical to the evolution of humans and infections left genetic code in our bodies which is still essential for life today, Stanford University has discovered.


Genetic material of ancient viruses still lingers in our DNA and could explain how humans differ so greatly from other animals.
Scientists already knew that the human genome (or blueprint) is littered with sequences left behind from long-ago viral infections but did not know if they were still having any impact.
“It's fascinating to imagine how, during the course of evolution, primates began to recycle these viral leftovers into something that's beneficial and necessary to our development,”

Jens Durruthy-Durruthy, Stanford University School of Medicine

Now researchers at Stanford University School of Medicine have found that genetic material from a retrovirus called HERV-H is not only active, but is crucial in allowing a fertilised human egg to grow into an embryo.
It suggests that millions of years ago the path to humanity was started by viral infections changing our DNA and could explain extraordinary evolutionary jumps which turned us into modern humans with larger brains and social skills.
"This is the first time that these virally derived molecules have been shown to be directly involved with and necessary for vital steps of human development," Dr Vittorio Sebastiano, assistant professor of obstetrics and gynaecology.

“What's really interesting is that these sequences are found only in primates, raising the possibility that their function may have contributed to unique characteristics that distinguish humans from other animals.
"We're starting to accumulate evidence that these viral sequences, which originally may have threatened the survival of our species, were co-opted by our genomes for their own benefit.
“In this manner, they may even have contributed species-specific characteristics and fundamental cell processes, even in humans.”
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Ancient viruses deposited genetic code into the blueprint of humans
Earlier this year Stanford found that early human embryos are packed full of viral RNA molecules created by left-behind genetic material.
The team was interested in finding out if these molecules affected how a fertilised human egg becomes pluripotent – or able to become any tissue in the body.
RNA usually works as a messenger molecule, reading a gene made up of DNA code, and telling the body to make a protein. However in this case the viral RNA was found to actually alter the activity of genes.

Until the breakthrough scientists had thought that most genetic material from viruses was inert and unable to cause any genetic changes in the body. But the new study suggests not only is it still functioning, but it is crucial to human life. When scientists removed the virus code the fertilised eggs were unable to grow.
The virus in question is called the HERV-H retrovirus. Such viruses spread by inserting their genetic material into the genome of an infected cell. If the infected cell is a sperm or an egg, the retroviral sequence can also be passed to future generations.
“It's fascinating to imagine how, during the course of evolution, primates began to recycle these viral leftovers into something that's beneficial and necessary to our development,” said co-author Jens Durruthy-Durruthy.

The research was published in the journal Nature Genetics.
Bron: http://www.telegraph.co.uk/news/sci...University.html , 23/11/2015, Sarah Knapton

Eigen mening:

Om even kort samen te vatten wordt er in het artikel gesproken over een nieuwe ontdekking gedaan aan de Stanford University op vlak van ons DNA.
De wetenschappers hebben ontdekt dat de restjes van virussen in ons DNA achterblijven. Over de jaren heen zet ons lichaam deze resten van virussen om zodat het lichaam deze kan gebruiken voor andere doeleinden.
Dit is belangrijk omdat deze aangepaste virussen ervoor gezorgd hebben dat wij belangrijke evolutionaire sprongen hebben gemaakt.
Naar mijn mening is dit een belangrijke ontdekking. Dat virussen ervoor zorgen dat ons lichaam toepassingen zoekt voor de stukjes genetische code die achterblijft kan ook voor de medische wereld van groot belang zijn. Met deze ontdekking zijn we echter ook al een stapje dichter bij het begrijpen waarom wij deze evolutionaire sprongen hebben gemaakt die ons de mensen van vandaag maakt. een van de virussen is zelfs zo belangrijk geworden dat wij ons niet kunne voortplanten als het afwezig is. Onze embryo's kunnen zich dan immers niet naar behoren ontwikkelen.