How Life Spawned: The Spontaneous Appearance of Primordial DNA

Scientists have taken a closer look at the origins of DNA and have found that the self-organization properties of DNA-like molecular fragments four billion years ago may have guided their own growth into repeating chemical chains long enough to act as a basis for primitive life.

What might have preceded the formation of unicellular organisms has long remained a mystery. That's why researchers closely examined a scenario for the non-biological origins of nucleic acids.

In the 1980s, researchers discovered that RNA had the ability to chemically alter its own structure. This led to the concept of an "RNA world" in which primordial life was a pool of RNA chains that were capable of synthesizing other chains from simpler molecules available in the environment. While scientists now know that RNA chains are too specialized to have been created as a product of random chemical reactions, the findings do provide a viable alternative.

The new research reveals that the spontaneous self-assembly of DNA fragments just a few nanometers in length into ordered liquid crystal phases has the ability to drive the formation of chemical bonds that connect together short DNA chains to form long ones without the aid of biological mechanisms. Liquid crystals are a form of matter that has properties between those of conventional liquids and those of a solid crystal.

"The new findings show that in the presence of appropriate chemical conditions, the spontaneous self-assembly of small DNA fragments into stacks of short duplexes greatly favors their binding into longer polymers, thereby providing a pre-RNA route to the RNA world," said Noel Clark, one of the researchers, in a news release.

The findings are published in the journal Nature Communications.

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