Zebrafish contains two Pax6 genes involved in eye development

Nornes, S., Clarkson, M., Mikkola, I., Pedersen, M., Bardsley, A., Martinez, J.P., Krauss, S., and Johansen, T.
Mechanisms of Development   77: 185-196 (Journal)
Registered Authors
Bardsley, Anne, Johansen, Terje, Krauss, Stefan, Nornes, Svanhild
zebrafish; Pax6; gene duplication; eye development
MeSH Terms
  • Amino Acid Sequence
  • Animals
  • Animals, Genetically Modified
  • Base Sequence
  • Cloning, Molecular
  • DNA-Binding Proteins/genetics
  • DNA-Binding Proteins/metabolism
  • Drosophila/genetics
  • Embryo, Nonmammalian
  • Eye/embryology*
  • Eye/growth & development*
  • Eye Abnormalities/embryology
  • Eye Abnormalities/genetics
  • Eye Proteins/genetics*
  • Eye Proteins/metabolism
  • Gene Expression Regulation, Developmental*
  • Homeodomain Proteins*
  • Humans
  • Mice
  • Molecular Sequence Data
  • Paired Box Transcription Factors
  • Repressor Proteins
  • Trans-Activators/genetics
  • Trans-Activators/metabolism
  • Zebrafish/embryology
  • Zebrafish/genetics*
9831649 Full text @ Mech. Dev.
The Pax6 genes of both vertebrates and invertebrates are expressed in the developing eye and in the central nervous system. These genes encode transcription factors with two DNA-binding domains, an N-terminal paired domain and a homeodomain separated by a flexible linker region. Ectopic eye structures are obtained upon targeted expression of Drosophila, squid, ascidian or mouse Pax6 genes in various imaginal disc primordia of Drosophila. We have previously cloned a Pax6 cDNA from zebrafish. Here we report the cloning of a novel Pax6 homolog from zebrafish denoted Pax6.2. The coding sequences of the two genes show 82% identity whereas the deduced amino acid sequences are 95% identical with complete conservation of the paired- and homeodomains. The embryonic expression patterns of Pax6.1 and Pax6.2 reveal both overlapping and discrete expression domains suggesting a division of labor between these two very similar gene products during development of brain and eye structures. Both Pax6.1 and Pax6.2 can act as transcriptional activators with Pax6.2 being more efficient than Pax6.1. Both Pax6.1 and Pax6.2 are able to induce ectopic eyes in Drosophila, while Pax2 is not, suggesting that eye induction is not a general feature of Pax family genes but a distinct characteristic of Pax6 and its direct homologs. Attempts to detect Pax6. 2 homologs in chick, mice or humans proved unsuccessful suggesting that this gene either was lost during evolution of higher vertebrates or, more likely, arose as part of a larger scale duplication of chromosome segments occurring in the zebrafish lineage.
Genes / Markers
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Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Engineered Foreign Genes