Fig. 1. tcf3b encodes a protein highly homologous to Hdl and is expressed throughout zebrafish embryogenesis. (A) Clustal alignment of Hdl and Tcf3b amino acid sequences. Dark-gray shading indicates identity and light gray indicates conservative substitutions. Homology is distributed throughout the proteins, but they are most divergent near the C terminus. (B) RT-PCR analysis shows that tcf3b is expressed maternally [0-2 hours post-fertilization (hpf)] and zygotically. max, which is expressed constantly throughout development (Schreiber-Agus et al., 1993), was used as a loading control.