Fig. 2: Freeze–thaw/pH cycling allows iterative cycles of RNA replication.
a, Schematic of conflicting conditions required for RNA strand separation (left) and triplet polymerization (right). b, Physicochemical cycling workflow that integrates strand separation and polymerization conditions. pH switching results in a build-up of KCl, and serial dilution allows continued cycling by resetting KCl concentrations and restoring ribozyme and triplet substrate levels. c, Iterative replication of the model RNA duplex AD and its constituent strands in replication buffer (4 nM template, substrates and primers from Fig. 1b). Also shown (for comparison) are a single-cycle eight-day polymerization reaction (1 × 8 days), and four-cycle reactions undergoing twofold dilution (4 ÷ 2) followed by an extra cycle (5). Full-length primer extension yields are expressed as percentages relative to the starting template. To compare efficiencies in the diluted 4 ÷ 2 and five cycle reactions, their yields should be doubled (×2).
