Fig. 1.

Embryos are similar sized at each stage with E− developmentally delayed.

Live imaging of embryos was performed at each developmental stage used for assays and shows that embryos are of similar size, as measured by egg diameter, egg yolk diameter and estimated egg yolk volume. At 12 hpf, E+ embryos (A) develop normally indicated by 5–6 somites. At the same stage, E− embryos (B) are developmentally delayed with reduced somites (*) and smaller anterior head region. By 24 hpf, the otic vesicle is apparent, myotomes are neatly packed in V-shapes and the tail begins to extend in E+ embryos (C). In a representative E− embryo, however, the otic vesicle is less visible, posterior myotomes are loosely packed and the tail extension is reduced (D, *). E+ embryos at 48 hpf (E) show pigment migration dorso-laterally and have experienced the first heartbeat with visible circulation in the pericardium. E− embryos at the same stage (F) have greater incidence of both yolk sac and pericardial edema (*). (A-B) are taken with a 10× objective, (C–F) are taken with a 2× objective. Image was generated in Adobe Photoshop and any manipulations (contrast, saturation) were performed uniformly across images at the same developmental stage.