FIGURE 2

Fos mutants and morphants have distinctive keyhole-shaped mouth and abnormal craniofacies. (A) Schematic of CRISPR guides targeting exons 1 and 4 of the fosab gene and resulting in an almost complete deletion of the coding region with a 1.523 kb deletion confirmed by DNA sequencing. (B–L) Representative brightfield images of 5dpf zebrafish showing normal phenotype (B) and abnormalities in fos F0 mutants (15/24 embryos, 63%) and morphants (102/132 embryos, 77%) (C and F) compared to UIC and MM controls (110/122 embryos, normal phenotype, 90%) (B, G). (D–M) Confocal images of rostrally mounted DAPI-stained samples showed a distinctively abnormal facial and mouth shape in both fos mutant (103 embryos) (H) and morphant (138 embryos) (I) embryos compared to UIC (93 embryos) (D) and MM (47 embryos) controls (I). Arrowheads indicate merged or displaced neuromasts. Co-injection of human FOS mRNA rescued the morphant phenotype (J and K) while overexpression alone caused other abnormalities including cyclopia and an elongated lower jaw (L, M). UIC, uninjected control; F0, crispant; MO, morpholino; MM, mismatch; Hu-FOS, human FOS mRNA.