Fig. 3

dsRNA causes nonspecific depletion of mRNA. Embryos are viewed from the animal pole in (b–e), from a lateral perspective with anterior to the left in (g–i) and (m–o), and from a rostral perspective in (j–l). Scale bar for (g–o) is 250 μm. (a) Region of the E. coli lacZ mRNA used to produce sense, antisense, and dsRNA preparations. (b–e) Expression patterns of endogenous tbx16/spt and β catenin in embryos at 40% epiboly after injection of either ss or dsRNA from the lacZ gene. spt (b) and β catenin (c) expression after lacZ dsRNA injection was depleted from sector-like regions of the blastoderm in a manner identical to that seen after 40 pg tbx16/spt dsRNA injection. Injection of sense (d) or antisense (e) lacZ RNA did not affect the embryos. (f) Comparison of the frequency of developmental defects at 26 hpf to head or tail of the embryo after injection of tbx16/spt or lacZ dsRNA. At 26 h after dsRNA injection the embryos were scored for defects in anterior structures (head), such as cyclopia (g–i), asymmetric eyes (j–l), or small or disorganized brain, and for posterior structures (tail), such as reduced anterior somites, or twisted foreshortened tails, and partial loss of notochord (m–o). Embryos in (h, k, n) have been injected with 40 pg lacZ dsRNA and embryos in (i, l, o) with tbx16/spt dsRNA. Between 22 and 54 (mean of 32) embryos were examined for each treatment. Black arrowheads in (g–i) indicate eyes and white arrowheads the ear. In (k, l), black arrowheads indicate the smaller, abnormal eye. The loss (n) or defective structure (o) of the notochord and the resulting abnormal somite shape are indicated with arrows in (n, o) and, for comparison, the same region of an uninjected embryo in (m).