Fig. 3

Depleting all four rars eliminates hox expression in the hindbrain. (A–I) Dorsal views of late gastrula stage embryos (8.5 hpf), labeled by whole mount in situ hybridization for cyp26a1 (A–C), hoxb1a (D–F), and hoxd4a (G–I). Anterior is to the top. Controls (left column), DEAB-treated (middle column) or quadruple morphants (rar-MO) injected with MOs targeting raraa, rarab, rarga and rargb. (J) Histogram summarizing results of quantitative PCR (qPCR) to detect relative amounts of the same three gene products, using RNA isolated from the siblings of embryos used for panels A–I. (A–C) No changes were detected in the pattern of cyp26a1 expression in presumptive forebrain and midbrain in DEAB-treated (B) or rar-MO quadruple morphants (C), but total levels were significantly reduced in both cases (J). (D–F) hoxb1a expression in presumptive hindbrain was dramatically reduced by DEAB treatments (E) and eliminated by rar-MO (F), and this was confirmed by qPCR (J). (G–I) hoxd4a expression was virtually eliminated by both DEAB treatments (H) and rar-MO (I), which was confirmed by qPCR (J).