FIG. 3.
Time course of RNAi inactivation. Cytoplasmic extracts were prepared from uninfected 293 cells (U) or cells collected at 8, 16, or 24 h postinfection (hpi) with adenovirus (wt900) M, DNA size marker; C, uninfected extract. The reaction was stopped at time zero. (A) Dicer activity assayed against a 1,600-base-pair dsRNA. si, 32P-labeled 21-base-pair siRNA marker. The arrow indicates the position of 21-base-pair siRNA products. (B) RISC activity in the same extracts assayed against a 484-nucleotide, uniformly labeled mRNA in the presence of a synthetic siRNA. The arrow indicates the position of the 252-nucleotide 5′ cleavage product. Quantitative results based on three independent experiments are shown below respective autoradiograms.