Figure 4.

Rescue of deadenylation and RNAi deficiencies in early embryos. (A) Suppression of siRNA_NS-mediated inhibition of deadenylation at MBT by exogenous Ago proteins. A ³²P-labeled Gb•B2 reporter RNA with a perfect match miR-427 target site in the 3′ UTR plus siRNA_NS (20 fmol per embryo) was injected alone or together with synthetic mRNA encoding wild-type or mutant Myc-hAgo2, and reporter RNA stabilities were monitored over time as in Figure 1A. The arrowhead indicates the 5′-terminal RNAi cleavage product. Note that, in the absence of exogenous hAgo proteins, siRNA_NS-mediated inhibition of deadenylation was alleviated late in gastrulation (stages 11 and 12.5), coincident with increased accumulation of endogenous zygotic xlAgo proteins (cf. Fig. 3A and Supplemental Fig. S3B). (B) Lack of RNAi in the absence of exogenous Ago2. The ³²P-labeled Gb•B2 reporter RNA was injected alone or together with siRNA₄₂₇ (100 fmol per embryo) or pre-miR-427 (Lund et al. 2009) into one- to two-cell embryos and analyzed as in A.