Fig. 7. Suppression of Sec13 expression in D. rerio results in a phenotype similar to that of crusher mutant embryos. (A) Control and Sec13 morphant (using morpholino oligonucleotide MO1) zebrafish embryos at 5 dpf were photographed following paraformaldehyde fixation. (B) Live embryos were photographed at higher magnification to visualize craniofacial features (from experiments using MO2). Arrows indicate the facial features and arrowheads the pectoral fins that are present in controls but missing or dysmorphic in Sec13 morphants; note the absence of extension of the head beyond the eyes and kinked pectoral fin in Sec13 morphants. (C) Alcian-blue staining of fixed embryos at 4 and 5 dpf (following microinjection of MO1) shows defective deposition of proteoglycans and lack of formation of cartilage in multiple areas of the head. mc, Meckel's cartilage; pec fin, pectoral fin. Arrows indicate facial features and arrowheads the pectoral fins in controls that are missing or dysmorphic in Sec13 morphants (arrowheads). (D) Scanning electron micrographs showing the dorsal, lateral and ventral views of control and Sec13 morphant 5-dpf zebrafish embryos. Note the perturbation of development of the frontal region of the head (arrowhead), the pectoral fins (arrows) and the eyes in Sec13 morphants. Scale bars: 0.2 mm. (E) Immunoblotting of lysates from dechorionated control or Sec13 morphant embryos confirms suppression of Sec13 expression and concomitant loss of Sec31A. Immunoblotting of these lysates for -tubulin is included as a loading control. Molecular-mass markers are shown in kDa.