Visualizing RNA polymers produced by hot wet-dry cycling

Area of Science:

• Astrobiology and Origin of Life research
• Prebiotic chemistry and molecular evolution

Background:

• The transition from abiotic chemistry to life may have involved RNA polymers.
• RNA molecules potentially served as catalysts (ribozymes) and genetic information storage.
• Prebiotic hot spring environments with wet-dry cycles are hypothesized to facilitate RNA polymerization.

Purpose of the Study:

• To experimentally verify the claim that wet-dry cycles in simulated prebiotic hot springs can produce RNA polymers.
• To visualize and characterize the products formed from mononucleotide solutions under varying wet-dry conditions.

Main Methods:

• Simulated wet-dry cycles of RNA mononucleotides (single and mixed) at room temperature (20°C) and elevated temperature (80°C).
• Microscopic observation and characterization of the resulting structures (patches, strands, polymers, rings).

Main Results:

• Wet-dry cycling at 20°C produced irregular stringy patches and crystal strands, likely stabilized by hydrogen bonds.
• Wet-dry cycling at 80°C yielded structures consistent with true RNA-like polymers, characterized by covalently bonded monomers.
• Ring structures with short polymer attachments were occasionally observed at elevated temperatures.

Conclusions:

• Non-enzymatic synthesis of RNA-like polymers and rings is feasible in freshwater hot springs under prebiotic conditions.
• The observed polymers possess sizes potentially sufficient for folding into functional ribozymes and genetic molecules.
• These findings support the hypothesis of RNA-based prebiotic chemistry in early Earth environments.