An siRNA ribonucleoprotein is found associated with polyribosomes in Trypanosoma brucei

A postnuclear supernatant from cells expressing MT40 dsRNA was either (A) mock-treated or (B) incubated with 100 U/mL of micrococcal nuclease for 30 min on ice. Extracts were fractionated by sedimentation through 5%–45% sucrose density gradients. Below each absorbance profile is the corresponding Northern blot with an MT40 sense riboprobe. The positions of the 40S and 60S subunits and of the 80S monosomes are indicated.