Fig. 2

Expression of dystrobrevin and dystrophin genes in muscle, kidney and gut development. (A–L) In situ mRNA hybridisation for dmd (A–E), dtng (F–H), dtna (I), drp2 (J), dtnb (K and K′), R-utrn (L and L′) in lateral flatmounts, anterior to left (A–L), or transverse sections, dorsal to top (K′, L′). (A–H) Expression of dmd and dtng mRNA in muscle begins to accumulate at ends of recently differentiated fibres (arrows in A and F) at the somite borders from 22s, and persists at that location until after hatching (B, C, E, G, H). By 3d, some head muscles express dmd (yellow arrowheads, D). (I–K) At 48 hpf, low mRNA levels of dtna, dtnb and drp2 are detected in muscle fibres in somites, but dtnb is also present in the pronephric duct (K and K′, arrowheads). (L) At 48 hpf, R-utrn mRNA is expressed strongly in the pronephric duct (black arrowheads) and in the lateral line neuromasts (red arrowheads, L and L′-right panel) and is diffuse in muscle. (M–U) Wholemount immunohistochemistry for utrophin (M–O), dystrophin (P–R) and β-sarcoglycan (S–U) in lateral flatmounts, anterior to left, in either diaminobenzidine staining (M–O), confocal stacks of one side of somites 12–14 (M′, O′, P′, R′, S′, U′), a single confocal scan (O″), or transverse section, dorsal to top (U′). By 25 hpf dystrophin (P, P′) and β-sarcoglycan (S, S&prime) proteins are detected in muscle fibres concentrated at fibre ends, whereas utrophin protein is more evenly spread in muscle fibres. After 48 hpf, utrophin protein (N–O′) labels fibres uniformly. Note the costameric expression of utrophin in slow fibres (white arrows, O″). Between 48 hpf and 5d, dystrophin (Q–R′) and β-sarcoglycan (T–U′) proteins are spread in muscle fibres, but remain concentrated mainly at fibres ends. Note the immunoreaction in the gut at 5d with all three proteins (arrowheads in O, R, U, U′). All bars 20 μm.