Fig. 3

Expression of dystrobrevin and dystrophin genes in head development. In situ mRNA hybridisation in dorsal flatmounts, anterior to left (A, B, D, F, J, K-right panel and L-right panel), wholemounts in lateral view, anterior to top (C, G, H, M–P) or to left (E-left panel, I, K and L-left panel), and transverse sections, dorsal to top (E-right panel, F-inset). (A–G) Dtng mRNA is expressed in r2 and r4–6 from 5s–15s whereas krox20 (red) is expressed in r3 and r5 (A–D, F). Expression is throughout the dorso-ventral axis of the rhombomere (F, inset), including neural crest precursors within and as they are leaving the neural tube (B, blue arrowheads at r6). By 22s, expression of dtng has declined in rhombomeres leaving the highest signal in r4 and away from rhombomere borders (G), and is lost by 26 hpf (N). Expression is also detected in the diencephalon between 5–15s concentrated at the left side (C, E, F, yellow arrowheads). Transverse section at the level of the dotted line (E) shows that expression is ventral and stronger at the midline and left of it. (H–L) Low level of dtna mRNA expression is detected throughout the brain with stronger expression in the hypothalamus from 20s to at least 26 hpf (black arrowheads) whereas pitx3 (red) stains the lens, posterior diencephalon and pituitary. Note dtna expression in the telencephalon at 26 hpf (green arrowheads). (M–P) Drp2 (M) is widely expressed in the developing brain at 26 hpf, whereas little dtnb, dtng and dmd brain expression is detected. r, rhombomere; vd, ventral diencephalon; h, hypothalamus; t, telencephalon; le, lens; pdn, posterior diencephalon; pt, pituitary.