ABSTRACT
Here we report the isolation and characterization of the olive fruit fly Bactrocera oleae genes orthologous to the Drosophila melanogaster sex-determining genes Sex-lethal (Sxl) and doublesex (dsx). Fragments of the Sxl and dsx orthologous were isolated with RT-PCR. Genomic and cDNA clones were then obtained by screening a genomic library and separate male and female cDNA adult libraries using the RT-PCR products as probes in both cases. B. oleae Sxl gene (BoSxl) expresses the same pattern of transcripts which encode for a single common polypeptide in both male and female flies. The gene shares a high degree of similarity in sequence and expression to its Ceratitis capitata orthologous and does not appear to play a key regulatory role in the sex-determining cascade. B. oleae dsx gene (Bodsx) expands in a chromosomal region of more than 50 kb, with 6 exons-5 introns, producing different sex-specific mRNAs, according to the Drosophila model. The cDNA sequences are almost identical to the gene orthologous of Bactrocera tryoni. Four repeat elements identical to the D. melanogaster TRA/TRA-2 binding sites have been found in the untranslated region of the female-specific exon 4, predicting a common regulatory splicing mechanism in all studied species of Diptera.
Subject(s)
Insect Proteins/genetics , Tephritidae/genetics , Amino Acid Sequence , Animals , Base Sequence , Blotting, Northern , DNA/chemistry , DNA/genetics , DNA, Complementary/chemistry , DNA, Complementary/genetics , DNA, Complementary/isolation & purification , DNA-Binding Proteins/genetics , Drosophila Proteins/genetics , Drosophila melanogaster/genetics , Exons , Female , Genes, Insect/genetics , Introns , Male , Molecular Sequence Data , RNA/genetics , RNA/metabolism , RNA-Binding Proteins/genetics , Sequence Alignment , Sequence Analysis, DNA , Sequence Homology, Amino Acid , Sex Factors , Transcription, Genetic/geneticsABSTRACT
This review summarizes structural and functional studies on medfly promoters and regulatory elements that can be used for driving sex-specific, conditional and constitutive gene expression in this species. Sex-specific and conditional promoters are important for generating transgenic sexing strains that could increase the performance of the Sterile Insect Technique while strong constitutive promoters are necessary for developing sensitive transgenic marker systems. The review focuses on the functional analysis of the promoters of two male-specific and heat shock medfly genes. A special emphasis is put on the potential utility of these promoters for developing transgenic sexing strains.
