Myf5 is required for the migration of the sternohyoideus (sh) primordia from anterior somites. The transcripts of myf5 (A), myod (B), and met (C) were detected in sternohyoideus (sh) premordia, fin bud (fb), and posterior hypaxial muscle (phm), that were derived from anterior somites at 36 hpf. Embryos injected with myf5-morpholino oligonucleotide (MO) and myod-MO to inhibit specifically myf5 and myod translations, respectively, expressed met at the stages indicated. The expression of met was almost lost in myf5 morphants; only slight signals were detected in the phm (D; arrow). However, met was expressed normally in myod morphants (E). At 48 hpf, myogenin was expressed in the sh, fb, and phm of wild-type (F) and myod morphants (H), but myogenin was not expressed in the sh, fb, or phm of myf5 morphants (G). Instead, the expression of myogenin was up-regulated in the trunk of myf5 morphants. Embryos derived from the transgenic line Tg(α-actin:RFP; I–K) were used. At 72 hpf, the sh, fb, and phm showing red fluorescent signal were clearly observed both in wild-type (I; arrow) and myod morphants (K; arrow) but not in myf5 morphants (J). For abbreviations, see the legend to Fig. 1.
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