From experimental clues to theoretical modeling: Evolution associated with the membrane-takeover at an early stage of life
Fig 2
The spread of the glycerophosphate-synthetase ribozyme (GR) and its co-spread with the nucleotide-synthetase ribozyme (NR) in RNA-based protocells.
For each subfigure, the upper panel shows the trend of protocells containing specific RNA species while the lower panel demonstrates the trend of the total molecule number of the relevant RNA species in the system. Legends: Cgr — protocells containing GR; Cnr — protocells containing NR; Cnrgr — protocells containing NR and GR; Cctl — protocells containing the control RNA species; gr — GR; nr — NR; ctl — the control RNA species (the legends apply to all the subfigures). For all the cases, an “empty” fatty-acid protocell is inoculated at step 1 × 103. (a) The de novo spread of GR among protocells. Wherein, at step 1 × 104, ten empty protocells are selected (arbitrarily, the same below), each inoculated with one GR molecule, and another ten empty protocells are selected, each inoculated with one control molecule. (b) The spread of GR in protocells containing NR. Wherein, at step 1 × 104, ten empty protocells are selected, each inoculated with one NR, and another ten empty protocells are selected, each inoculated with one control; at step 3 × 105, ten NR protocells are selected, each inoculated with one GR, and another ten NR protocells are selected, each inoculated with one control. (c) The spread of NR in protocells containing GR, Wherein, at step 1 × 104, ten empty protocells are selected, each inoculated with one GR, and another ten empty protocells are selected, each inoculated with one control; at step 3 × 105, ten GR protocells are selected, each inoculated with one NR, and another ten GR protocells are selected, each inoculated with one control. (d) An evolutionary case without inoculation of the RNA species – first, NR occurs naturally in empty protocells, and then GR occurs naturally in NR protocells. PRL = 5 × 10-6. The characteristic sequence of GR is “CCAUGUA” – only two nucleotides different from that of NR (default sequence: “GCACGUA”, see the footnotes of Table 1); the control species adopts a characteristic sequence of “UCAGGUA”, two nucleotides different from either of the two ribozymes.