Fig. 8

Detection of molecular regulators of skeletogenesis in uxs1 mutant cartilage. (A–N) In situ hybridization on horizontal sections through the ceratohyal for sox9a (A–D), sox9b (E, F), runx2a (G, H), runx2b (I–L), and erm (M, N). Wild-type chondrocytes in the mid-diaphyseal region showed decreased sox9a expression from 3 dpf (A) to 5 dpf (C) as they matured. Not only did chondrocytes of uxs1^hi3357 mutants fail to show this down-regulation over time (B, D), but in addition, sox9a expression overall was much higher in mutants compared to wild types. Expression of sox9b was absent in wild-type chondrocytes at 3 dpf (E), but transcripts were detected in uxs1 mutants (F). runx2a expression was obvious in perichondrium of wild types at 3 dpf (G), but was absent in uxs1 mutants (H). runx2b expression was found in perichondrium of wild types at 3 dpf (I) and 5 dpf (K), but was not easily detected in perichondrium of mutants at these timepoints (J, L). In addition, chondrocyte expression of runx2b was much higher in uxs1 mutants compared to wild types at 3 and 5 dpf. Expression of the FGF-responsive gene erm was found in just a few wild-type chondrocytes at 3 dpf (M), whereas erm transcripts were at high levels in all uxs1 mutant chondrocytes (N). Abbreviations: ch, ceratohyal; md, mid-diaphyseal region; pe, perichondrium.