Fig. 7

Rescue of mtmr12 morphant phenotypes by MTM1.

The ability of human MTM1 or MTMR12 transcripts to rescue abnormalities seen in morphant zebrafish was classified in to phenotypic index of five groups: Normal, mild, moderate, severe and dead, described in the table depending on body length, birefringence and ultrastructure of skeletal muscle. (A) Polarized light microscopy of 3 dpf live embryos showed that birefringence of mtmr12 morphant embryos increased significantly upon overexpression of human MTM1 mRNA. (B) Overexpression of human MTMR12 mRNA in mtm1 morphant fish resulted in a mild rescue of skeletal muscle defects as seen by birefringence of zebrafish embryos. (C) Overexpression of human MTM1 mRNA in mtm1-mtmr12 morphant fish resulted in a moderate rescue of skeletal muscle defects as seen by birefringence of zebrafish embryos. (D) Electron microscopy showed normal skeletal muscle structure of mtmr12 and mtm1-mtmr12 morphant fish rescued with MTM1 mRNA but displayed disorganized triads in mtm1 morphants that were rescued with MTMR12 mRNA. (E) Quantification of the body length and disorganized triads in morphant and rescued fish. Body length was measured in 10–15 embryos in each group. Total number of triads were counted in at least 15 myofibers within each embryo (n = 5 embryos). Pd0.05.