Figure 4.

Simultaneous injection of two nonoverlapping MOs against prom3 results in a synergistic effect. A–F, embryos were injected at the one-cell stage with control MO (A, ctrl, 10 ng), MO2 (D, 10 ng) or a combination of MO1 + MO2 against prom3 at the doses indicated (B, C and E, F). At 58 hpf, larvae were observed in a native, unfixed state (A–D) or processed for whole-mount ISH using antisense DIG-labeled probe against cmlc2 (E and F). At the effective dose (10 ng), MO2 elicited mild to severe phenotypes (D). The simultaneous injection of one-fourth of their single effective amounts of MO1 (5 ng) and MO2 (10 ng) results in body axis distortion and fluid backup (C) similar to the severe phenotype detected upon injection of MO2 alone at the effective dose (D). Application of one-eighth of effective amounts caused no changes in body axis development (B) but often elicited L-R defects of the heart tube (F) in contrast to the normal position (situs solitus) (E). Orientation is as follows. A–D, random; E and F, anterior (dorsal toward the top). A, atrium; V, ventricle.