Very high conservation between Cyp6a2 from Drosophila melanogaster and its ortholog Cyp6a26 from D-simulans

Although Drosophila simulans is closely related to D. melanogaster, very few cytochrome P450 genes have been studied in this species until now. As Cyp6a2 from D. melanogaster is a major gene implicated in the detoxification of xenobiotic molecules, we decided to look for its ortholog in D. simulans. The isolated gene, Cyp6a26, presents structural characteristics very similar to those of Cyp6a2: an identical size of 1 590-bp comprising two exons separated by a 69-bp intron and a nucleotide sequence homology of 95%. Many putative transcriptionally important motifs were identified in the upstream DNAs of the two genes but only 16 elements are in common positions. Treatment of flies with phenobarbital leads to an increased production of Cyp6a26 mRNAs. The expression of Cyp6a26 mRNAs varies following developmental stages in the same manner as Cyp6a2. Immunohistochemistry experiments of phenobarbital-treated adult drosophila show that the spatial expression pattern of the two proteins is also conserved between the two species. All these data argue in favor of the conservation of the function of these homologous genes between the two Drosophila species.