Knockdown of sec24c, and combined loss of sec24d and sec24c phenotypes.
Analysis of wild types (A, E, I), sec24c-UTR-MO (B,F,J), bulldog (C, G, K) and double sec24c-UTR-MO+ sec24d-UTR-MO (D, H, L) injected embryos. (A–D) Images of live wild types (A), sec24c-UTR-MO, (2.0 ng injected, B), bulldog (C) and sec24c-UTR-MO+ sec24d-UTR-MO (2.0 ng each, D). The sec24c morphants have reduced body length (blue arrows), but the head appears normal. Double morphants for sec24d+sec24c are significantly shorter than bulldog larvae, almost completely lack fin-folds and have reduced jaw region (red arrow) and pronounced heart edema (D). (E–H) Alcian blue preparations of the head skeleton. The Alcian blue staining confirms normal craniofacial cartilages in sec24c morphants. (I–L) Histological sections counter-stained with toluidine blue at 4 dpf. Insets indicate the plane of the sections. (I,J) Histological, sagittal plastic sections stained with toluidine blue show normal jaw opening and surrounding cartilages in wild types (I) and sec24c morphants (J). Purple staining patterns for glycosaminoglycans of the ECM are also comparable. In contrast, the pharyngeal skeleton of sec24d+sec24c double mutants fails to stain with Alcian blue (H). Histological sections reveal patterned arches that are largely devoid of metachromatically stained cells (L). Abbreviations: cb, ceratobranchial; ch, ceratohyal; ep, ethmoid plate, m, Meckel′s cartilage.