Fig.2 Effect of gRNA length on RNA knock-down efficiency. (A, B) The results of 30 nt gRNA of Luciferase. Renilla luciferase activity is used as a reference. Samples transfected with Luc/Rluc and Cas13 but without gRNA are considered negative control. (C, D) The results of 20 nt gRNA of Luciferase. (E) The scheme describes the strategy for choosing different PFS invariant gRNA. (F, G) The efficiency of different length of gRNA action with same 5’PFS (F) and 3’PFS (G). (H, I) The efficiency of different length of gRNA action with same 5’PFS (H) and 3’PFS (I) of another site Luc3.12 which Cas13b showed better efficiency than Cas13d with 30 nt gRNA. All results are representative of at least three independent experiments. The results are presented as mean ± SD. Data are analyzed by one-way ANOVA. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.