A hidden code in our DNA explains how new pieces of genes are made

We’re all here thanks to mutations. Random changes in genes are what create variety during a species, and this can be what allows it to adapt to new environments and eventually evolve into a completely new species. But most random mutations actually disrupt the functions of our genes then are a standard source of genetic diseases.

This ambiguity creates a good challenge. On the one hand, mutations are needed for biological innovation, and on the opposite hand, they cause diseases. How does nature resolve this conflict? Research by me and my colleagues suggests that one answer could exist an order that enables evolution to innovate while minimizing the disruption this will create.

This code is hidden within a component of our genome (the complete set of our genetic material) referred to as repetitive genetic elements, which we now know plays a key role in evolution. These elements are sequences within our DNA which will make many copies of themselves. so as to create the proteins that our bodies need, our cells take instructions from our DNA by transcribing it into the same molecule called RNA. But in rare cases, rather than building a protein, some RNA molecules convert into DNA and insert themselves at new locations in our genome.

In this way, the repetitive elements can continually create new copies of themselves. As a result, the human genome contains thousands of repetitive elements that aren't present in the other species because they need to copy themselves since humans evolved.

But repetitive elements aren’t just useless copies. Barbara McClintock, the scientist who discovered them in 1948, showed they'll act as switches that switch genes on and off in maize. This was initially thought to be an obscure phenomenon with no relevance for humans. Yet now it's become clear that repetitive elements are a vital toolkit for evolution. By turning genes on and off, the repetitive elements can influence what characteristics a species evolves. they need been useful for biological innovations, like the evolution of pregnancy in mammals.

Perhaps the foremost elegant example of this is often within the evolution of the peppered moth. This moth normally has light-colored wings, but during Britain’s age, a repetitive element inserted itself into the gene that controls the color pattern of the wings. As a result, a black strain of the peppered moth evolved and this allowed it to blend in and escape its predators amid the polluted environment.

So what does all this should do with managing the disruption of mutations? Our research looks at the repetitive elements that were copied within the genome of the ancestors of contemporary primates. There are over 1.6m of those “Alu elements” dispersed everywhere in the human genome, and a few of them have accumulated random mutations that enabled them to become functional parts of our genes.

We have found a code within the RNA that controls Alu elements hiding inside human genes. This code combines competing for positive and negative molecular forces, sort of a yin and yang in our cells. it's well-known that competing molecular forces control many aspects of our genes. In our case, the positive force (acting through the protein called U2AF65) allows the Alu elements to stay a part of RNA and also the resulting protein. The negative force (acting through the protein called hnRNPC) opposes this and removes the weather from the RNA.

We’ve known for many years that evolution has to tinker with genetic elements so that they can accumulate mutations while minimizing disruption to the fitness of a species. Research, published within the journal eLife, checked out over 6,000 Alu elements to indicate that our code does exactly this.

The two forces are tightly coupled in evolution, so as soon as any mutations make the ying stronger, the yang catches up and stops them. this enables the Alu elements to stay during a harmless state in our DNA over long evolutionary periods, during which they accumulate plenty of change via mutations. As a result, they decrease harm and gradually start escaping the repressive force. Eventually, a number of them tackle a very important function and have become indispensable pieces of human genes.

To put it otherwise, the balanced forces buy the time needed for mutations to create beneficial changes, instead of disruptive ones, to a species. And this is often why evolution proceeds in such small steps – it only works if the 2 forces remain balanced by complementary mutations, which takes time. Eventually, important new molecular functions can emerge from randomness.

These findings tell us that humans don't seem to be a set pinnacle of evolution. Our genomes are like those of the other species: a fluid landscape of DNA sequences that keep changing. This explains how our genome can host its ever-changing repetitive elements despite their potential to disrupt the prevailing order in our cells.