Fig. 3. raldh2 morpholino induced phenocopies and rescue of mesodermal and
pectoral fin development in nls through RA application. (A,B)
Expression of krox20 and myoD, dorsal views. (A) Injection
of a raldh2-morpholino into wild-type phenocopies the mesodermal
defects in nls. (B) 10-6 M RA rescues mesoderm development
in nls (12 hpf); brackets indicate the postotic head. (C-L) Wild-type
(middle panels) and nls (right panels) embryos in dorsal (E-J) or
lateral (C,D,K,L) view, anterior towards the left. (C-F) In situ hybridisation
reveals an absence of tbx5.1 expression, which marks forelimb
mesoderm, in nls at the 12-somite stage (C,D), as well as later
during fin outgrowth at 28 hpf (E,F). (G,H) at 32 hpf, shh
expression, a marker for posterior fin mesenchyme, is absent in nls
embryos. (J,L) 36 hpf, 10-7 M RA rescues tbx5.1 expression
in nls pectoral fin buds (arrow); rescued fin buds often develop
apical folds (L, arrow), although never as progressed in growth as in wildtype
siblings.
