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Fig. 6 Ultra-structural analysis of rbfox1l/rbfox2 morphants reveals disorganized sarcomeres that are reduced in number. Electron micrographs of longitudinal sections of 48 hpf wildtype muscle at 390× and 6000× magnification reveal highly ordered sarcomeres with electron dense Z disks terminating with T-tubules at the sarcoplasmic reticulum (asterisks in C), which contrasts sharply with the dramatic reduction in sarcomere number and organization observed in rbfox1l/rbfox2 morphants at the same magnification (compare A, C with B, D). In the latter, vesicles of the sarcoplasmic reticulum are disorganized and T-tubules are not observed or are unidentifiable at Z-disk boundaries (asterisk in D). Cross sections at 390× and 4000× reveal defects in overall muscle fiber size as well as thick and thin filament arrangement between wildtype embryos and rbfox1l/rbfox2 morphants (E, G vs. F, H). Scale bars = 2.0 μm (A–B, E–F), 0.2 μm (C–D, G–H).
Reprinted from Developmental Biology, 359(2), Gallagher, T.L., Arribere, J.A., Geurts, P.A., Exner, C.R., McDonald, K.L., Dill, K.K., Marr, H.L., Adkar, S.S., Garnett, A.T., Amacher, S.L., and Conboy, J.G., Rbfox-regulated alternative splicing is critical for zebrafish cardiac and skeletal muscle functions, 251-61, Copyright (2011) with permission from Elsevier. Full text @ Dev. Biol.