Fig. 5

Non-muscle myosin and unc45b mRNAs are up-regulated in early unc45b mutant embryos. In situ hybridization of embryos at the 5-somite (A, C, E, G, I) and 10-somite (B, D, F, H, J) stages. Approximately 50 embryos were examined for each stage and marker. WT and unc45b mutant embryos were identified by dCAPS genotyping. Color development in unc45b mutant embryos (right-hand embryo in all panels) was much more rapid than in WT embryos (left-hand embryo in all panels) for non-muscle myosin myh10 (A, B), indicating up-regulation of mRNA expression. This increase is concurrent with the up-regulation of unc45b mRNA expression (C, D). RNA expression of myogenic regulators myoD (E, F) and myf5 (G, H) were not increased detectably in mutants at the 5-somite stage (compare left and right embryos in panels E and G). At the 10-somite stage, myf5 remained unaffected (H), but myoD mRNA expression was somewhat increased in unc45b mutants (F), concurrent with the onset of significant muscle myosin expression. smyhc1 mRNA expression was not affected at either stage (J, I).