Genetic ablation of PRDM3 causes subtle craniofacial defects in zebrafish and mid-gestation lethality in mice. (A–E) Wildtype and prdm3−/− zebrafish embryos were collected at 6 dpf and stained for Alcian blue and Alizarin red. (A) Images of dissected viscerocranium and neurocranium of wildtype (wt) and prdm3−/− embryos. prdm3−/− embryos and their cartilage phenotypes were present in Mendelian ratios (B). (C–F) Quantification of cartilage elements, Meckel’s cartilage to palatoquadrate (horizontal black double arrow in wt viscerocranium of A) (C), distance between trabeculae (vertical black double arrow in wt neurocraium of A) (D), length of parashenoid tissue (E), and area of mineralized parasphenoid (F). ceratobranchial arches (cbs), ceratohyal (ch), Meckel’s cartilage (m), opercle (op), palatoquadrate (pq), parasphenoid (ps), trabeculae (tr), (n = 6 for each group measured). Scale bar, 100 μm. (G–H) Ventral views of in situ hybridization for col2a1 (G) and dorsal views of in situ hybridization for runx2b (H) in prdm3 mutants or wildtype controls at 48 hpf. ceratobranchial arch 5 (cb5), cleithrum (cl), eye (e), opercle (op). Black arrow heads indicate decreased expression in the cartilage and bone elements of the neurocranium and viscerocranium. Scale bar, 250 μm. (I–J) Prdm3fl/fl females were bred for timed matings to Prdm3Δ/+;Sox2+/Tg males and embryos were collected at the indicated timepoints. Shown are lateral (top) and ventral (bottom) gross phenotypes of mutant animals (I). Scale bar 750 μm. (J) Prdm3Δ/Δ;Sox2+/Tg and control embryos were collected at E13.5 and stained with Alcian blue. Shown are lateral views of the head. Meckel’s cartilage (mc). *p ≤ 0.05, **p ≤ 0.005, #p ≤ 0.1, Student’s t-test.
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