Fig. 1

Loss-of-Mrdr function specifically results in dorsalized phenotypes. (A and B) Live embryos at 30 hpf, either uninjected (A) or injected with rdr^gtMO (10 ng; B) showing all characteristics of rdr^Δ1 zygotic mutant haploids, including reduced eyes (arrow) and neural cell death (arrowheads). (C) RT-PCR products of transcripts from uninjected and rdr^gtMO-injected embryos using primers amplifying the region of the targeted splicing event were run on a 3% agarose gel. The morphant PCR product has the expected size (3,967 kb) and sequence of a transcript retaining intron 1. ef1α amplimers are shown as reverse transcription quantitative controls. (D–P) Live embryos at 24 hpf (D–I) and 30 hpf (J–P) either uninjected (D and J) or injected (E–I and K–P) with the MOs/mRNAs described in each right lower corner. Unless stated otherwise, doses used per embryo were rdr (1 pg), rdr^DN (150 pg), and rdr^atgMO (15 ng). Arrowheads and arrows in E and G–I denote Zrdr^MO and Mrdr^MO features, respectively. (K–M) C2–C4 dorsalized rdr^DN-injected embryos. (N and O) V3 (strong) and V1 (mild) ventralized embryos. Arrowhead in O marks the V1-characteristic reduced eye size. All views are lateral, anterior to the left. h, head; s, somite; nt, notochord; yt, yolk tube; vv, ventral vein; vtf, ventral tail fin. (Q) rdr^atgMO specifically blocks rdr mRNA but not alk8 mRNA translation in vitro. rdr (Left) or alk8 (Right) mRNAs (1 μg) were translated in vitro in the presence of rdr^atgMO or alk8^MO at the indicated concentrations (40, 8, 1.6, or 0 μM), then translation products were resolved. (C) No mRNA added in the translation reaction. (P and R) Rescue of rdr^DN phenotypes with rdr mRNA.