Modules G, H, and I are functionally conserved in humans. (a) VISTA comparison (90% identity over 25 base pairs) of the medaka olSix3.2 genomic region plotted against those of other vertebrates, as indicated. The analysis identifies highly conserved noncoding regions (pink peaks) corresponding to modules G (asterisk) and L (two asterisks), and to a partial I element (blue asterisk). The light and dark blue peaks correspond to the 5'-untranslated region and coding sequence of Six3, respectively. (b) Nucleotide sequence alignment of module I from different vertebrates where partially or completely conserved sequences are indicated in blue or red, respectively. Nonconserved sequences are in black. The nucleotide positions are relative to the human genomic sequence. (c) Schematic representation of the human (h-cI) and Xenopus (X-cI) constructs, containing the G (red box), H, and I sequences, used to generate transient Xenopus and stable transgenic medaka lines. The mixed H and I sequences are represented as a striped blue and yellow box. (d, f, and h) Bright field images and (e, g, and i) epi-fluorescence dorsal views of h-cI transgenic medaka embryos at different stages of development, as indicated in the panels. (j and k) Lateral views of St35 Xenopus embryos hybridized with a specific probe for Xsix3.2 or injected with X-cI. Note that in both Xenopus and medaka embryos reporter expression recapitulates Six3 expression at the corresponding stages of development.
Conte and Bovolenta Genome Biology 2007 8:R137 doi:10.1186/gb-2007-8-7-r137