Figure 4.

Degradation of targeted mRNA in response to dsRNA is reduced in AGO1 mutants. Gel of uniformly ³²P-labeled mRNA that was incubated in extracts prepared from AGO1^k08121 (−) and GFP-expressing AGO1⁺ (+) embryos. Before the addition of labeled mRNA, the extracts were incubated with or without unlabeled dsRNA. Samples collected just after the addition of mRNA (0) or after a 1-h incubation (1) are in neighboring lanes. There is some nonspecific degradation of the mRNA after 1 h in the embryo extracts as seen in the “no dsRNA” controls. However, the amount of mRNA is greatly reduced in (+) extracts preincubated with homologous dsRNA. mRNA is unaffected in extracts prepared from AGO1 mutants. Extracts prepared from a viable revertant line derived from l(2)k08121 (rev) are able to degrade targeted mRNA. Similarly, extracts prepared from AGO1^k08121 embryos rescued with an AGO1 cDNA (rescue) degrade mRNA targeted with homologous dsRNA.