The zebrafish Pax3 and Pax7 homologues are highly conserved, encode multiple isoforms and show dynamic segment-like expression in the developing brain.

This study describes the isolation and characterization of zebrafish homologues of the mammalian Pax3 and Pax7 genes. The proteins encoded by both zebrafish genes are highly conserved (>83%) relative to the known mammalian sequences. Also the neural expression patterns during embryogenesis are very similar to the murine homologues. However, observed differences in neural crest and mesodermal expression relative to mammals could reflect some functional divergence in the development of these tissues. For the zebrafish Pax7 protein we report the first full-length amino acid sequences in vertebrates and show the existence of three additional isoforms which have truncations in the homeodomain and/or the C-terminal region. These novel variants provide evidence for additional isoform diversity of vertebrate Pax proteins.

Embryonic expression and DNA-binding properties of zebrafish pax-6.

Zebrafish pax-6 (pax[zf-a]) and its murine homologue are structurally and functionally related to the Drosophila paired box gene eyeless, a master control gene for eye development. This report details the zebrafish pax-6 embryonic expression pattern both at the mRNA and protein level. Transcripts are first detected in the presumptive forebrain and hindbrain regions of the neural plate. After formation of the neural keel, Pax-6 protein accumulates within the same two domains. Expression is also observed in the optic vesicles and lens placodes, confirming that the Pax-6 protein is expressed in those areas of the eye where it is assumed to control differentiation. The relative DNA-binding affinity of the zebrafish Pax-6 protein to different categories of Pax recognition sites is shared with the murine homologue.