Experimental evolution toward the emergence of life
My ultimate goal is to directly observe the prebiotic evolutionary process in a laboratory, where life emerges from an assembly of molecules. People believe that the first primitive life appeared on the ancient Earth as a simple molecule and then gradually evolved to become present-day complex life forms. However, this scenario is totally speculative. No one has ever witnessed the evolutionary process from molecules to life. A direct method to understand this prebiotic process is to establish an experimental model that mimics primitive life forms and observe the evolutionary process in real time.
As an experimental model of a primitive system in the RNA-protein world, we have constructed a translation-coupled RNA replication (TcRR) system that have the ability to evolve. Using this system, we obtained the following findings.
1). Cell-like compartments of adequate size were required for evolution (ref. 1)
2). Parasitic RNAs spontaneously appeared in the system and co-replicated with the host genomic RNA showing oscillation dynamics (ref. 2).
3). The existence of parasites is not just a burden but allows endless evolution of the host RNA (unpublished).
In the future, I have three plans. Frist, I would like to evolve the TcRR system to become more complex and closer to the extent life. Second, I am going to make more primitive systems using the TcRR system as a starting point. Through these studies, I would understand required conditions for the prebiotic evolution from molecules to life. Third, I would like to collaborate with the Earth scientists at ELSI to understand when and where these required conditions were satisfied on the ancient Earth. With this collaboration, I, together with ELSI members, will be able to propose possible prebiotic evolution with actual experimental evidence, which contributes to the ELSI's ultimate aim, understanding the origin of life.
1. Ichihashi, N., Usui, K., Kazuta, Y., Sunami, T., Matuura, T., Yomo, T.,
Nature Communications, 4, 1-7, (2013)
2. Bansho, Y., Furubayashi, T., Ichihashi, N.*, Yomo, T.* (*co-corresponding author)
Proc Nat Aca Sci USA, 113, 4045-4050 (2016)