Supplementary Figures, Figure Legends, and Tables.

images of the pharynx of wild-type and mut-2(-) animals that express GFP in the pharynx (left panels) and that in addition coexpress gfp-dsRNA and DsRed in the pharynx (middle and right panels). The representative animals presented in these grey scale images show that wild-type animals silence gfp expression (green channel) more potently than mut-2(-) animals even in response to lower levels of gfp-dsRNA (red channel). (b) Feeding RNAi of wild-type and mut-2(-) animals. L4 animals were fed either L4440 (control) or dsRNA targeting the body-wall muscle gene unc-22 (bwm) or the skin gene dpy-7 (skin) and the percentage of L4 progeny that showed the corresponding defects were determined. Error bars indicate 95 % confidence intervals and asterisks indicate significant differences (P>0.05). (c) A representative transgene that expresses gfp-dsRNA in the pharynx (phar::gfp-dsRNA) in sur-5::gfp animals was crossed into mut-2(-); sur-5::gfp animals and the number of brightly fluorescent gut nuclei were counted. n=25 L4 animals. Averages (red bars), significant differences (brackets and *, P<0.05) and similar values (brackets) are indicated