Isolation and expression of Pax6 and atonal homologues in the American horseshoe crab, Limulus polyphemus

Dev Dyn. 2008 Aug;237(8):2209-19. doi: 10.1002/dvdy.21634.


Pax6 regulates eye development in many animals. In addition, Pax6 activates atonal transcription factors in both invertebrate and vertebrate eyes. Here, we investigate the roles of Pax6 and atonal during embryonic development of Limulus polyphemus rudimentary lateral, medial and ventral eyes, and the initiation of lateral ommatidial eye and medial ocelli formation. Limulus eye development is of particular interest because these animals hold a unique position in arthropod phylogeny and possess multiple eye types. Furthermore, the molecular underpinnings of eye development have yet to be investigated in chelicerates. We characterized a Limulus Pax6 gene, with multiple splice products and predicted protein isoforms, and one atonal homologue. Unexpectedly, neither gene is expressed in the developing eye types examined, although both genes are present in the lateral sense organ, a structure of unknown function.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Basic Helix-Loop-Helix Transcription Factors / genetics*
  • Cloning, Molecular
  • Eye / embryology
  • Eye Proteins / chemistry
  • Eye Proteins / genetics*
  • Eye Proteins / metabolism
  • Gene Expression Regulation, Developmental*
  • Homeodomain Proteins / chemistry
  • Homeodomain Proteins / genetics*
  • Homeodomain Proteins / metabolism
  • Horseshoe Crabs / embryology
  • Horseshoe Crabs / genetics*
  • Immunohistochemistry
  • In Situ Hybridization
  • Molecular Sequence Data
  • Myosin Type III / genetics
  • Nerve Tissue Proteins / genetics*
  • PAX6 Transcription Factor
  • Paired Box Transcription Factors / chemistry
  • Paired Box Transcription Factors / genetics*
  • Paired Box Transcription Factors / metabolism
  • Phylogeny
  • Protein Structure, Tertiary
  • Repressor Proteins / chemistry
  • Repressor Proteins / genetics*
  • Repressor Proteins / metabolism
  • Sequence Homology, Amino Acid


  • Basic Helix-Loop-Helix Transcription Factors
  • Eye Proteins
  • Homeodomain Proteins
  • Nerve Tissue Proteins
  • PAX6 Transcription Factor
  • Paired Box Transcription Factors
  • Repressor Proteins
  • Myosin Type III