Emergence of life in compartmentalized molecular systems

David Lacoste, PhD, CNRS Directeur de Recherches at Gulliver laboratory, ESPCI, France

To maintain information in a molecular system, it must be somehow replicated, but an accurate replication is only possible below a certain length for the molecules that carry the information. Above that threshold, information loss occurs, as shorter molecules called parasites take over the system, preventing information rich molecules to be replicated. Transient compartmentalization is a way to get around this issue, allowing parasites to be controlled and information to be passed along generations. Experiments using compartmentalized RNA molecular systems have confirmed this scenario. When carried on for a long time, these experiments have also shown that coevolution of parasites and replicases also take place within an ecosystem of increasing complexity. Here we present a theoretical model of transient compartmentalization that accounts for mutations, evolution with a gradual improvement of fitness and co-evolution. In collaboration with the group of R. Mizuuchi from Waseda University from Japan, we benchmark our model with a serial dilution experiment that displays complex oscillatory dynamics among four well-characterized RNA replicators. We also perform other experiments to quantify the level of mixing in compartments when stronger stirring tends to homogenize their composition. We then model stirring-induced mixing and show how stirring alters the dynamics of compartmentalized replicators. We conclude that compositional memory arising from transient compartmentalization plays a major role in the dynamics of early molecular systems.

Reference
B. Ledoux et al., Compositional memory matters for early molecular systems, PNAS in press (2026),
https://www.biorxiv.org/content/10.64898/2026.03.03.709225v2