The transformer gene in Bactrocera oleae: the genetic switch that determines its sex fate

Insect Mol Biol. 2007 Apr;16(2):221-30. doi: 10.1111/j.1365-2583.2006.00717.x. Epub 2007 Feb 6.


Transformer (tra) is the second gene of a regulatory cascade based on RNA splicing that determines sex in Drosophila melanogaster. Splicing of tra transcripts is regulated by the master gene Sex lethal and tra itself regulates splicing of the transcriptional regulator doublesex (dsx). We present the isolation and characterization of Botra, the olive fruit fly Bactrocera oleae orthologue to the Drosophila gene transformer. As in Drosophila, Botra transcripts are spliced in a sex-specific manner so that only females encode a functional polypeptide of 422 amino acids, whereas males encode presumably nonfunctional peptide(s). The identification of multiple TRA/TRA-2 binding sites within the Botra male-specific exons, suggests an autoregulation mechanism of tra, through TRA/TRA2 activities. The fundamental role of the TRA protein in sex determination of Bactrocera was investigated by RNA interference, where the introduction of Botra dsRNA into embryos resulted in complete transformation of XX flies into fertile males.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Drosophila Proteins
  • Female
  • Fertility
  • Genome, Insect
  • Homeostasis / genetics
  • Insect Proteins / genetics*
  • Karyotyping
  • Male
  • Molecular Sequence Data
  • Nuclear Proteins / genetics
  • RNA Interference
  • RNA, Double-Stranded
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sequence Analysis, DNA
  • Sex Determination Processes*
  • Tephritidae / genetics*


  • Drosophila Proteins
  • Insect Proteins
  • Nuclear Proteins
  • RNA, Double-Stranded
  • Tra protein, Drosophila