Regulation of mdkb transcription. A-D: Effect of inhibition of RA signaling on mdkb expression. A: Lateral view of mdkb expression in a dimethylsulfoxide (DMSO) -treated control embryo at 8.5 hours postfertilization (hpf). B: Lateral view of an embryo treated with 10 μM DEAB. Arrow indicates area of reduced mdkb expression. C: Group of DMSO-treated control embryos showing regular mdkb expression. D: Embryos treated with 10 μM DEAB showing reduced mdkb expression. E-H: Effect of FGF inhibition on mdkb expression. Lateral view of a control embryo at 9 hpf (E) and an embryo treated with 50 μM SU5402 (F). Arrow indicates area with reduced mdkb expression. Groups of control embryos (G) and SU5402-treated embryos (H) showing mdkb expression. I-L: Lateral views of embryos showing expression of mdkb in noninjected control embryos (I,K) and embryos injected with 30 pg of medaka fgf8 mRNA (J,L showing mdkb expression. I-L: Lateral views of embryos showing expression of mdkb in noninjecte) at 9 hpf. Arrowheads in I,J indicate the extension of the mdkb expression domain; yp, yolk plug. M-O: Expression of mdkb in embryos incubated with 0.3 M LiCl. Arrowheads mark the mid-hindbrain boundary (MHB), and asterisks mark the most anterior mdkb expression domain. (M) Control embryo. Note that mdkb expression is increased in embryos treated with LiCl at shield stage (N) and at 70% epiboly (O). P,Q: Expression of mdkb and her1 in wild-type or heterozygous (P) and homozygous (Q) mindbomb mutants (mibta52b). Note unaltered mdkb but reduced her1 expression in the tail bud of homozygous mib mutants (marked by asterisk). Insets show dorsal views of tail bud regions in P and Q.
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