Liquid crystals and the origin of life

October 3, 2018, American Chemical Society
Liquid crystals formed by short RNA strands, revealed by polarized optical microscopy. Credit: American Chemical Society

The display screens of modern televisions, cell phones and computer monitors rely on liquid crystals—materials that flow like liquids but have molecules oriented in crystal-like structures. However, liquid crystals may have played a far more ancient role: helping to assemble Earth's first biomolecules. Researchers reporting in ACS Nano have found that short RNA molecules can form liquid crystals that encourage growth into longer chains.

Scientists have speculated that life on Earth originated in an "RNA world," where RNA fulfilled the dual role of carrying genetic information and conducting metabolism before the dawn of DNA or proteins. Indeed, researchers have discovered catalytic RNA strands, or "ribozymes," in modern genomes. Known ribozymes are about 16-150 nucleotides in length, so how did these sequences assemble in a primordial world without existing ribozymes or proteins? Tommaso Bellini and colleagues wondered if liquid crystals could help guide short RNA precursors to form longer strands.

To find out, the researchers explored different scenarios under which short RNAs could self-assemble. They found that at high concentrations, short RNA sequences (either 6 or 12 nucleotides long) spontaneously ordered into phases. Liquid crystals formed even more readily when the researchers added magnesium ions, which stabilized the crystals, or polyethylene glycol, which sequestered RNA into highly concentrated microdomains. Once the RNAs were held together in liquid crystals, a chemical activator could efficiently join their ends into much longer strands. This arrangement also helped avoid the formation of circular RNAs that could not be lengthened further. The researchers point out that and the chemical activator would not be found under primordial conditions, but they say that other molecular species could have played similar, if less efficient, roles.

Explore further: Research reveals inner workings of liquid crystals

More information: "Nonenzymatic Polymerization into Long Linear RNA Templated by Liquid Crystal Self-Assembly" ACS Nano (2018). pubs.acs.org/doi/abs/10.1021/acsnano.8b05821

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RobertKarlStonjek
1 / 5 (1) Oct 03, 2018
Each of the foundational properties of life has, or eventually will, be considered to be the most primary property and therefore precursory form of life, RNA just being the most recent.

This is simply a fashion or fad. Other properties of life such as the cell have been proposed as the precursory form and Colloids, for instance, have been proposed as the precursory form. Others have considered homoeostasis as the fundamental form, or reproduction and have come up with replicating systems or self governing systems as the most fundamental.

And then the fashion changes. The only logical precursor is all of them being around in some form. It is the coming together of various systems, properties and/or phenomena that identifies life on Earth and it is the interaction of systems within the individual organism, the environment of the entire biota that has been a feature of life for more than 3,000 million years, which would not have been the first feature of life?
RobertKarlStonjek
not rated yet Oct 18, 2018
1/5 ?...apparently the facts of life don't agree with someone...

'RNA World' is just wishful thinking, though a very useful exercise RNA world is nothing more than the possible genesis of viruses which are not even considered alive and can't exist in the absence of pre-existing living cells...neither can RNA...

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