Fig. 9

Precocious bone formation and osteoblast differentiation in perichondria of fam20b and xylt1 mutants.

A–F, Alcian blue/Alizarin red-stained ceratohyals. G–I, live Alizarin red fluorescence of fam20b^b1127;Tg(sp7:EGFP)b1212 and xylt1^b1128;Tg(sp7:EGFP)b1212 larvae. J–O, whole-mount in situ hybridization of 4 dpf ceratohyals. No signs of Alizarin red staining were observed at 3 dpf in ceratohyals of wild types (A), or fam20b^b1127 (B) or xylt1^b1128 (C) mutants. By 4.5 dpf, Alizarin red staining was still absent from ceratohyals of wild-type larvae (D, arrow), although it was detected in ceratohyals of fam20b^b1127 (E, arrow) and xylt1^b1128 (F, arrow) mutants. Both GFP expression and Alizarin red staining were at background levels in the perichondrium of the ceratohyal in 4.5 dpf wild types (G, arrow), but were obvious in the fam20b^b1127 and xylt1^b1128 mutant perichondria (H,I, arrow). At 4 dpf, col10a1 expression was not detected in the ceratohyal perichondrium of wild types (J, arrow), but was expressed highly in fam20b^b1127 (K, arrow) and xylt1^b1128 (L, arrow) mutant perichondria. Abbreviations: bsr = branchiostegal ray.