Partial de-repression of slow-twitch genes in
mutant larvae. (A-C)
smych1, tpm2 and mylz10 remain restricted to the slow-twitch fibers in wild-type larvae at 3 or 4 days postfertilization (dpf). (D-F) All three genes are ectopically expressed in some fast-twitch fibers in sox6 mutants by 3 or 4 dpf. (G-G”)
smyhc1:GFP expression (green) is excluded from fast-twitch fibers (red) in 5 dpf wild-type larvae. (H-H”) In sox6 mutant larvae at 5 dpf, a subset of fast-twitch fibers ectopically express the reporter gene (H). The expression of the fast-twitch myosin revealed by mAb F310 (red) in the fast domain remains unaffected in sox6 mutants (cf G’ and H’).