Figure 2.

(A) Time-dependent fluorescence changes generated by the Mg²⁺-ion-dependent DNAzyme reporter units associated with the constituents of CDN “X” undergoing the emergence and selection processes and (B) concentrations of the constituents of CDN “X” derived from the respective catalytic activities shown in part A, by using the appropriate calibration curves (Figures S3 and S4): (i) upon mixing constituent AA′ with hairpin H_BB′ at time t = 0 h; (ii) in CDN “X” generated after the cleavage of H_BB′ by AA′ (t = 24 h); (iii) after the treatment of evolved CDN “X” with EcoRI that induces the biocatalytic selection of BA′. (C) Time-dependent fluorescence changes generated by the Mg²⁺-ion-dependent DNAzyme reporter units associated with the constituents of CDN “Y” during the cascaded catalytic emergence and selection processes, and (D) concentrations of the constituents of CDN “Y” derived from the respective catalytic activities shown in part C, by applying the appropriate calibration curves (Figures S6 and S7): (iv) in the mixture of hairpins H_CC′ and H_DD′, in the presence of the survived BA′, at time t = 0 h; (v) in CDN “Y” emerged upon subjecting H_CC′ and H_DD′ to the survived BA′ for 24 h; (vi) after treatment of the resulting CDN “Y” with HindIII to stimulate the selection of DC′. The error bars in parts B and D were derived from N = 3 experiments. (E) Schematic emergence of CDN “X” and EcoRI-induced selection of constituent BA′ from CDN “X” followed by the BA′-dictated emergence of CDN Y and HindIII-guided survival of constituent DC′.