Divergent functions of orthodenticle, empty spiracles and buttonhead in early head patterning of the beetle Tribolium castaneum (Coleoptera)

Dev Biol. 2008 May 15;317(2):600-13. doi: 10.1016/j.ydbio.2008.03.005. Epub 2008 Mar 15.

Abstract

The head gap genes orthodenticle (otd), empty spiracles (ems) and buttonhead (btd) are required for metamerization and segment specification in Drosophila. We asked whether the function of their orthologs is conserved in the red flour beetle Tribolium castaneum which in contrast to Drosophila develops its larval head in a way typical for insects. We find that depending on dsRNA injection time, two functions of Tc-orthodenticle1 (Tc-otd1) can be identified. The early regionalization function affects all segments formed during the blastoderm stage while the later head patterning function is similar to Drosophila. In contrast, both expression and function of Tc-empty spiracles (Tc-ems) are restricted to the posterior part of the ocular and the anterior part of the antennal segment and Tc-buttonhead (Tc-btd) is not required for head cuticle formation at all. We conclude that the gap gene like roles of ems and btd are not conserved while at least the head patterning function of otd appears to be similar in fly and beetle. Hence, the ancestral mode of insect head segmentation remains to be discovered. With this work, we establish Tribolium as a model system for arthropod head development that does not suffer from the Drosophila specific problems like head involution and strongly reduced head structures.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Body Patterning / physiology*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / physiology*
  • Drosophila
  • Drosophila Proteins / genetics
  • Drosophila Proteins / physiology*
  • Gene Expression Regulation, Developmental*
  • Head / anatomy & histology
  • Head / embryology*
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / physiology*
  • Models, Animal*
  • Phylogeny
  • RNA Interference
  • Species Specificity
  • Transcription Factors / genetics
  • Transcription Factors / physiology*
  • Tribolium / anatomy & histology
  • Tribolium / embryology*
  • Tribolium / metabolism

Substances

  • DNA-Binding Proteins
  • Drosophila Proteins
  • Homeodomain Proteins
  • Transcription Factors
  • btd protein, Drosophila
  • ems protein, Drosophila
  • oc protein, Drosophila