THE BACTROCERA-TRYONI HOMOLOG OF THE DROSOPHILA-MELANOGASTER SEX-DETERMINATION GENE DOUBLESEX

A homologue of the bifunctional sex-determining gene, doublesex (dsx), has been identified in the tephritid fruit fly, Bactrocera tryoni, an d has been found to be expressed in a sex-specific manner in adult fli es. The male- and female-specific cDNAs are identical at their 5' ends but differ at their 3' ends and appear to be the products of alternat e splicing. The level of identity of the sex-specific DSX proteins of B. tryoni with the D. melanogaster DSX proteins, across the region cor responding to the DNA binding domain and the oligomerization domains, is greater than 85%. Four sequence motifs which are ten to thirteen ba ses identical to the TRA/TRA-2 binding sites (thirteen-nucleotide repe at sequences) are present in the female-specific exon of the B. tryoni dsx gene.