FIGURE 7.
Control of heart laterality by later RA signaling after 2So is mediated by asymmetric bmp4. A–C, in embryos with both BMS453 treatment from 2So to 53 hpf and predominant distribution of bmp4MO on the right side, 61.4, 16.5, and 22.1% developed D-loop (p < 0.0065; n = 127) (A), L-loop (p < 0.0021; n = 127) (B), and midline (p < 0.02; n = 127) (C) heart, respectively. Living Tg(cmlc2:GFP) transgenic embryos were observed at 53 hpf. p values were calculated against embryos treated with BMS453 from 2So to 53 hpf. D and E, in wild type embryos at 10So, 81.8% exhibited slightly asymmetric raldh2 with stronger expression on the left side in the anterior LPM (D), whereas 13.6% showed symmetric raldh2 expression (E). The line marks the position of the section plane shown in F and G. F, sections illustrated asymmetric expression of raldh2 in the anterior LPM at 10So. G, in situ image of the section was overlaid with DAPI counterstaining. H and I, slightly asymmetric expression of raldh2 in the anterior LPM initiated at 1–2So (H) and became evident at 3–4So (I). J, 73.9% of spaw morphants showed slightly asymmetric raldh2 with stronger transcription on the left side in the anterior LPM. Arrowheads mark the transcription of raldh2 in the anterior LPM. WT, wild type.