Fig. 1

The vertebrate gene cordon-bleu (cobl) is conserved in zebrafish, with enriched expression in ciliated epithelial tissues.

(A) Conservation of the KRAP motifs and WH2 domains among zebrafish, mouse and human Cobl orthologs. The two putative, conserved functional domains are colored. The proline-rich KRAP motifs show 100% amino acid sequence similarity, while three WH2 domains show 80–95% amino acid sequence similarity among these species. (B) RT-PCR amplification of cobl sequences from RNA harvested at progressively later developmental stages. Zfcobl is present in eggs and embryos prior to zygotic gene expression, and is expressed at all stages thereafter. RT-PCR for gapdh is shown as a loading control. (C) zfcobl is expressed ubiquitously at low levels during gastrulation. Here, at 90% epiboly, zfcobl shows no tissue-specific enrichment. The axial midline is marked with a dashed line. Arrow denotes the dorsal lip of the blastopore. Tissue-specific enrichment does not appear until 2 somites, in the neural keel. (D) cobl expression in Kupffer′s vesicle, denoted by arrowhead, and in the neural keel during somitogenesis. (E) cobl expression in neural keel, pronephric anlagen, otic placode and midbrain–hindbrain boundary. (F-J) cobl enrichment in ciliated epithelial tissues at 24 hpf. (G) Cross-section through posterior neural keel; (H) sensory placodes of the otic vesicle; (I) the pronephric duct; (J) nasal placodes. K = KRAP, W = WH2, mhb = midbrain–hindbrain boundary, ovs = otic vesicle sensory placodes, pst = proximal straight tubule, np = nasal placode, dbl = dorsal blastopore lip.