Zebrafish frizzled7b is expressed in prechordal mesoderm, brain and paraxial mesoderm

Frizzled (fz) genes encode receptors for the Wnt signaling pathway. We describe a novel fz gene, zebrafish fz7b. Maternal fz7b mRNA is detectable by RT-PCR. Embryonic fz7b is widely distributed in early epiboly stage embryos. By shield stage, expression appears enriched around the blastoderm margin. During epiboly, expression becomes restricted to the prechordal plate, presumptive midbrain and hindbrain and paraxial mesoderm. As somites form, labeling is briefly present in a segmental pattern. By mid-somitogensis, expression is particularly enriched in the forebrain, the forebrain-midbrain boundary, and the anterior hindbrain, but appears at lower levels throughout much of the rostral CNS. The CNS expression is at ventral and medial positions. The paraxial mesoderm expression becomes restricted to the tailbud. This pattern continues through 26 h. At 48 h, weak expression is seen in the pharyngeal arches and developing fin.