Fig. 6

Downstream region is responsible for the RA-mediated regulation of hoxb1b. (A?H) Wild-type embryos (A, B, E, F) or 3′5′hoxGFP Tg embryos (C, D, G, H) were untreated (A, C, E, G), treated with RA at the shield stage (B, D), or treated with DEAB at the shield stage (F, H), and cultured until 80% epiboly, when the expression of hoxb1b (A, B, E, F) or 3′5′hoxGFP (egfp) (C, D, G, H) was examined by WMISH. Numbers of embryos showing the expression pattern represented by the photos vs. numbers of stained embryos are shown at the bottom-right. (I?L) 3′5′hoxGFP Tg embryos (I, J) or 5′hoxGFP Tg embryos (K, L) were untreated (I, K) or treated (J, L) with RA at the shield stage and allowed to develop to the 8-somite stage, when GFP expression was observed. (M?P) 3′5′hoxGFP Tg embryos were untreated (M) or treated with RA during the specified periods (N?P) and observed for fluorescence at the 8-somite stage. (Q?T) 3′5′hoxGFP Tg embryos were untreated (Q, S) or treated (R, T) with DEAB for 3 h and examined for fluorescence at the specified stages. RA-induced reporter expression in the polster was also observed for the RARE from RARβ-2 (Perz-Edwards et al., 2001), suggesting that this ectopic expression is inherent in the function of the RARE. Anterior expression boundaries of the transgene are marked with open arrowheads. (A?H, Q?T) Dorsal views with anterior to the top. (I?P) Lateral views with anterior to the left. p, polster; scale bars, 200 μm.