FIGURE 1. RNAi in C. elegans.

Silencing of a green fluorescent protein (GFP) reporter in C. elegans occurs when animals feed on bacteria expressing GFP dsRNA (a) but not in animals that are defective for RNAi (b). Note that silencing occurs throughout the body of the animal, with the exception of a few cells in the tail that express some residual GFP. The signal is lost in intestinal cells near the tail (arrowhead) as well as near the head (arrow). The lack of GFP-positive embryos in a (bracketed region) demonstrates the systemic spread and inheritance of silencing.