title: The Pax gene eyegone facilitates repression of eye development in Tribolium.
abstract: BACKGROUND
  The Pax transcription factor gene eyegone (eyg) participates in many developmental processes in Drosophila, including the Notch signaling activated postembryonic growth of the eye primordium, global development of the adult head and the development of the antenna. In contrast to other Pax genes, the functional conservation of eyg in species other than Drosophila has not yet been explored.
  
  
  RESULTS
  We investigated the role of eyg during the postembryonic development of the red flour beetle Tribolium castaneum. Our results indicate conserved roles in antennal but not in eye development. Besides segmentation defects in the antenna, Tribolium eyg knockdown animals were characterized by eye enlargement due to the formation of surplus ommatidia at the central anterior edge of the compound eye. This effect resulted from the failure of the developing gena to locally repress retinal differentiation, which underlies the formation of the characteristic anterior notch in the Tribolium eye. Neither varying the induction time point of eyg knockdown nor knocking down components of the Janus kinase/Signal Transducer and Activators of Transcription signaling pathway in combination with eyg reduced eye size like in Drosophila.
  
  
  CONCLUSIONS
  Taken together, expression and knockdown data suggest that Tribolium eyg serves as a competence factor that facilitates the repression of retinal differentiation in response to an unknown signal produced in the developing gena. At the comparative level, our findings reveal diverged roles of eyg associated with the evolution of different modes of postembryonic head development in endopterygote insects as well as diversified head morphologies in darkling beetles.
authors.affiliation: Department of Biological Sciences, Wayne State University, 5047 Gullen Mall, Detroit, MI 48202, USA.
authors.forename: Nazanin
authors.initials: N
authors.lastname: ZarinKamar
authors.affiliation: Department of Biological Sciences, Wayne State University, 5047 Gullen Mall, Detroit, MI 48202, USA.
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Biological Sciences, Wayne State University, 5047 Gullen Mall, Detroit, MI 48202, USA.
authors.forename: Riyue
authors.initials: R
authors.lastname: Bao
authors.affiliation: Institut fur Spezielle Zoologie und Evolutionsbiologie, Friedrich Schiller Universitat Jena, Erbertstrasse 1, 07743 Jena, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Friedrich
authors.affiliation: Institut fur Spezielle Zoologie und Evolutionsbiologie, Friedrich Schiller Universitat Jena, Erbertstrasse 1, 07743 Jena, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Beutel
authors.affiliation: Department of Biological Sciences, Wayne State University, 5047 Gullen Mall, Detroit, MI 48202, USA.|Department of Anatomy and Cell Biology, Wayne State University, School of Medicine, 540 East Canfield Avenue, Detroit, MI 48201, USA.
authors.forename: Markus
authors.initials: M
authors.lastname: Friedrich