(CN) — Researchers at the University of Tokyo created a simple RNA molecule that can diversify into something more complex through evolution.
According to a study published Friday in the journal Nature Communications, the research could illuminate the origins of life by examining how RNA molecules started to replicate and develop the complexity of living organisms.
The study “has provided the first empirical evidence that simple biological molecules can lead to the emergence of complex lifelike systems,” according to a statement accompanying the research.
RNA molecules are necessary for several cell functions. While DNA serves as the genetic blueprint of an organism, RNA is used to copy and transport that genetic blueprint.
The researchers incubated RNA molecules in droplets. After five hours, they changed the environment by adding more droplets without RNA molecules and stirring the solution vigorously. As this process went on, the RNA molecules mutated and evolved in the changing environment.
The experiment stems from a hypothesis that RNA molecules existed during Earth’s early days, along with other proteins and biological molecules. Approximately 4 billion years ago, the molecules began self-replicating, evolving from simple single molecules to progressively more diverse and complex molecules. The theory is that all life on earth, from plants to animals, emerged from this increasing diversity and complexity. The researchers’ experiment tested the long-term replication of RNA and successfully documented the chemical system’s shift toward a complex, biological system.
“We found that the single RNA species evolved into a complex replication system: a replicator network comprising five types of RNAs with diverse interactions, supporting the plausibility of a long-envisioned evolutionary transition scenario,” said Ryo Mizuuchi, professor at the University of Tokyo and one of the study’s authors.
The researchers said the study was notable because it demonstrated “a unique RNA replication system that can undergo Darwinian evolution.” Mutations and natural selection spurred the molecules to adapt to better survive in their shifting environment.
“We initially doubted that such diverse RNAs could evolve and coexist,” said Mizuuchi, explaining that biological principles generally dictate that multiple species cannot coexist if they are competing for the exact same resources.
“Not only did the RNA diversify, but they innovated different replication strategies to become coexistent by forming a network without outcompeting each other,” Mizuuchi said. The network the molecules developed helped them all replicate. “They are just molecules and their remarkable ability of evolution just surprised me.”
Going forward, Mizuuchi said the “evolution experiment is just beginning” and could help answer other questions regarding how living systems emerged, including biological functions like metabolism or the development of the contemporary genome structure.
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