Figure 2. crRNA screen. A. The IS711-crRNA-1-4 structure and the corresponding target sequences. The target sites are highlighted in blue, and PAM sequences are marked red. B. Product of Cas12a cleavage, 20 μl of each reaction was electrophoresed (2% agarose), M: DL 500 DNA marker (Takara, Code No.3590Q), 1-4: crRNA-1-4, (RPA amplification products were 340 bp, 261/79 for crRNA-1, 303/37 for crRNA-2, 310/30 for crRNA-3, 174/166 for crRNA-4), N: negative control. Figure 2C Four groups of crRNAs were screened by the quantitative fluorescence method. The reaction was performed at 42oC for 40min, and the signal was collected every minute. The reaction entered the plateau phase at 8-10min. As shown in the figure, the endpoint fluorescence value of crRNA-2 was slightly higher than that of crRNA-1 and crRNA-3, significantly higher than crRNA-4.