Figure 6

Figure 6

Details of ultrastructural defects in neb mutants. (A–U) Transmission electron micrographs of zebrafish embryos at 6 dpf. (A) Aligned sarcomeres in wt muscle. (B–E) Increased vacuolation of the sarcoplasmic reticulum in neb¹⁵, neb¹¹, neb³⁴, neb²¹ mutants (arrowheads). (F) Z-disks in wt muscle (arrowheads). (G–J) Significantly thicker Z-disks in neb¹⁵, neb¹¹, neb³⁴, neb²¹ mutants (arrowheads). (K) No abnormal protein aggregates have been observed in wt muscle. (L, M, and O) Electron-dense structures with a fibrous composition were observed in neb¹¹, neb¹⁵, neb²¹ (arrowheads). (L and N) Accumulation of ribosomes were observed in neb¹⁵ and neb³⁴ mutants (arrows). (Q) Normal triad structure and organization in wt muscle (arrowhead). (R–U) Triad structure and organization did not seem to be defective in neb mutants (arrowheads), except in splice mutant neb³⁴, where enlarged terminal cisternae were observed (arrows). Scale bars A-O = 500 nm. Scale bars Q-U = 100 nm.