The Sp8 zinc-finger transcription factor is involved in allometric growth of the limbs in the beetle Tribolium castaneum

Anke Beermann, Manuel Aranda, Reinhard Schröder*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

50 Scopus citations


Members of the Sp gene family are involved in a variety Of developmental processes in both vertebrates and invertebrates. We identified the ortholog of the Drosophila Sp-I gene in the red flour beetle Tiribolium castaneum, termed T-Sp8 because of its close phylogenetic relationship to the vertebrate Sp8 genes. During early embryogenesis, T-Sp8 is seen in segmental stripes. During later stages, T-Sp8 is dynamically expressed in the limb buds of the Tribolium embryo. At the beginning of bud formation, T-Sp8 is uniformly expressed in all body appendages. As the limbs elongate, a ring pattern develops sequentially and the expression profile at the end of embryogenesis correlates with the final length of the appendage. In limbs that do not grow out like the labruin and the labium, T-Sp8 expression remains uniform, whereas a two-ring pattern develops in the longer antennae and the maxillae. In the legs that elongate even further, four rings of T-Sp8 expression can be seen at the end of leg development. The role of T-Sp8 for appendage development was tested using RNAi. Upon injection of double stranded T-Sp8 RNA, larvae develop with dwarfed appendages. Affected T-Sp8RNAi legs were tested for the presence of medial and distal positional values using the expression marker genes dachshund and Distal-less, respectively. The results show that a dwarfed T-Sp8RNAi leg consists of proximal, medial and distal parts and argues against T-Sp8 being a leg gap gene. Based on the differential expression pattern of T-Sp8 in the appendages of the head and the thorax and the RNAi phenotype, we hypothesise that T-Sp8 is involved in the regulation of limb-length in relation to body size - a process called allometric growth.

Original languageEnglish (US)
Pages (from-to)733-742
Number of pages10
Issue number4
StatePublished - Feb 2004
Externally publishedYes


  • Allometric growth
  • Leg elongation
  • Serrate
  • Sp8
  • Tribolium

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology


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