sp5l is required for promoting the effect of ectopic Fgf signals on posterior neuroectodermal genes. Embryos were uninjected (WT) (A,D,G), or injected with 2 pg of fgf17b mRNA (B,E,H) or 2 pg of fgf17b mRNA plus 5 ng of sp5l-MO (C,F,I), and examined by in situ hybridization for the expression of gbx2 at the bud stage (A-C), hoxb1b at the 90% epiboly stage (D-F), and krox20 at the bud stage (G-I). All embryos were shown in lateral views with animal pole to the top and dorsal to the right. Embryos injected with fgf17b mRNA had an elongated axis and showed an anterior shift and ventral expansion of the marker gene expression domains (B,E,H). Coinjection with sp5l-MO inhibited the effect of fgf17b overexpression (C,F,I). Statistical data are summarized in J. The affected embryos were those that showed anterior shift and ventral expansion of the expression domain. Compared to wildtype and fgf17b-injected embryos, some of affected embryos that were coinjected with fgf17 mRNA and sp5l-MO showed weaker expression though the expression domain still shifted anteriorly and expanded ventrally.
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