Fig. 12.

Inhibition of BMP signalling by DMH1 or by heat shocking dnBMPR zebrafish embryos rescues early cartilage maturation gene expression and perichondral bone formation in fam20b mutants. (A-H) Compared with DMSO-treated (A,B) or heat-shocked (E,F) fam20b^−/− chondrocytes, DMH1-treated fam20b^−/− (C,D) or heat-shocked dnBMPR; fam20b^−/− (G,H) chondrocytes had decreased expression of the chondrocyte maturation genes ihha and col10a1a at 72 hpf (i.e. after 24 h of DMH1 treatment, or 2 days after heat shock). These are representative images from at least 12 samples for each group (at least six samples each from two clutches). (I-L″) Compared with respective control groups (I-I″,K-K″), perichondral bone appeared to decrease in DMH1-treated fam20b^−/− (i.e. 1 day after end of 48 h treatment; J-J″) or heat-shocked dnBMPR; fam20b^−/− (i.e. 4 days after heat shock; L-L″) embryos at 5 dpf. (M) Quantitation of 60 embryos (20 embryos each from three clutches) for each experimental group of the DMH1 experiment and of 80 embryos (20 embryos each from four clutches) for each experiment group of the dnBMPR experiment confirmed a significant decrease in perichondral bone of DMH1-treated fam20b^−/− or heat-shocked dnBMPR; fam20b^−/− embryos (*P<0.05, one-way ANOVA and paired Student's t-test). Scale bars: 50 μm (A-H); 200 μm (I-L″). A, anterior; AB/AR, Alcian Blue/Alizarin Red; Ch, ceratohyal cartilage; Chb, ceratohyal bone; Hm, hyomandibular bone; Hs, hyosymplectic cartilage; HS, heat-shocked; L, lateral.