Fig. 1

esrra is expressed in cartilaginous regions during zebrafish embryogenesis.

(A–L) Embryos at the indicated stages were subjected to in situ hybridization to analyse expression of esrra, sox9a, sox9b and col2a1. Arrows in (E–L) indicate pharyngeal arches where cartilage development occurs. Note that expression of esrra is largely overlapping with that of sox9a, sox9b and col2a1. (M–R) Embryos were injected with either MOctrl or MOesrra, raised to 48 hpf or 72 hpf as indicated, and analysed by in situ hybridization for expression of myod and acta2. myod expression in somites (arrows) is drastically decreased as muscle becomes differentiated from 48 hpf to 72 hpf in control embryos (compare M and O), while it sustains in MOesrra-injected embryos (compare N with P). In contrast, robust expression of acta2, a differentiated muscle marker, in control embryos is almost lost in MOesrra-injected embryos (compare Q with R). In addition, expression of myod in the pharyngeal arches (red asterisks) does not change from 48 hpf to 72 hpf in MOesrra-injected embryos, while myod in control embryo is expressed in a different subset of cells at 72 hpf as compared to that in 48 hpf. Embryos are shown in lateral views with anterior to the left except I–L where embryos are shown in ventral views.