Rp-dl knockdown embryonic phenotypes. Embryos resulting from control (A,C,E,G,I) or Rp-dl (B,D,F,H,J) parental RNA interference (pRNAi). (A,B) At the blastoderm stage control (ctrl) embryos present a posteriorly localized germ rudiment (GR) that is diagonally displayed (A, as in Figure 2B), while the Rp-dl RNAi GR is anteriorly localized and perpendicular to the egg’s long axis. (C,D) After gastrulation the head, thorax (Th), and growth zone (Gz) are seen in control (C) MalE RNAi embryos, but are not distinguished in (D) the Rp-dl RNAi. (E,F) Stage 5 and (G,H) stage 6 embryos show the correct formation of appendages in control (E,G) MalE RNAi embryos, while (F,H) Rp-dl RNAi embryos present only appendage-like structures (App.) that are seen in 25% of cases. These structures cannot be identified as head (H.App.) or thoracic appendages (Th. App.). Ab, abdomen. (I-J’) After gastrulation, amnion (Amn), ectodermal (Ect) and mesodermal (Mes) layers are distinguished in control embryo transverse sections stained with Alexa 647-phalloidin and nuclear Hoescht (I,I’). Shown are embryo sections in the middle (I) and posterior (I’) regions of the egg. Rp-dl RNAi (J,J’) embryos placed at the egg anterior form a hollow tube (Ect) with no distinguishable mesodermal layer, as seen in transverse (J) and longitudinal (J’) sections. Note that these embryos are localized adjacent to the egg surface. The asterisks in J point to the hollow embryo interior. Lateral view of embryos in (A,B; A slightly tilted ventrally), dorsal view in (C-H). However, embryo dorso-ventral placement in Rp-dl RNAi is randomized. (K) Relative mRNA levels for mesodermal genes in control and Rp-dl RNAi embryos (four biological replicates). Rp-twist and Rp-snail show a tendency to decrease in Rp-dl knockdowns.