Evolutionary conservation of Ceratitis capitata transformer gene function.
Transformer functions as a binary switch gene in the sex determination and sexual differentiation of Drosophila melanogaster and Ceratitis capitata, two insect species that separated nearly 100 million years ago. The TRA protein is required for female differentiation of XX individuals, while XY individuals express smaller, presumably nonfunctional TRA peptides and consequently develop into adult males. In both species, tra confers female sexual identity through a well-conserved double-sex gene. However, unlike Drosophila tra, which is regulated by the upstream Sex-lethal gene, Ceratitis tra itself is likely to control a feedback loop that ensures the maintenance of the female sexual state. The putative CcTRA protein shares a very low degree of sequence identity with the TRA proteins from Drosophila species. However, in this study we show that a female-specific Ceratitis Cctra cDNA encoding the putative full-length CcTRA protein is able to support the female somatic and germline sexual differentiation of D. melanogaster XX; tra mutant adults. Although highly divergent, CcTRA can functionally substitute for DmTRA and induce the female-specific expression of both Dmdsx and Dmfru genes. These data demonstrate the unusual plasticity of the TRA protein that retains a conserved function despite the high evolutionary rate. We suggest that transformer plays an important role in providing a molecular basis for the variety of sex-determining systems seen among insects.
Dipartimento di Genetica, Biologia Generale e Molecolare, Università degli Studi di Napoli Federico II, Naples, Italy.
Attilio
A
Pane
Annamaria
A
De Simone
Giuseppe
G
Saccone
Catello
C
Polito
D000818:Animals; D030801:Animals, Genetically Modified; D033622:Ceratitis capitata / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics*; D019143:Evolution, Molecular; D005260:Female; D049452:Green Fluorescent Proteins; D009687:Nuclear Proteins / Q000235:genetics*; D009841:Oligonucleotides; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012733:Sex Differentiation / Q000235:genetics*; D013045:Species Specificity
D018076:DNA, Complementary; D029721:Drosophila Proteins; D009687:Nuclear Proteins; D009841:Oligonucleotides; C097162:Tra protein, Drosophila; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins