Electrophoresis of the RNA. Electrophoresis of the RNA–toxin complex was performed in a 3% agarose gel (No. A-9539, Sigma Chemical Co., St. Louis, MO) in Tris-phosphate buffer, pH 8.0, at 4°C. After electrophoresis, the RNA position in the agarose gel was detected by visualizing ethylene blue dye under UV light.