Isolation of alpha cluster esterase genes associated with organophosphate resistance in Lucilia cuprina

PCR primers designed from the alpha-esterase gene cluster of Drosophila melanogaster have been used to isolate fragments from eight esterase genes in the Australian sheep blowfly, Lucilia cuprina. Phylogenetic analysis suggests that three are homologues of the alpha E7, alpha E8 and alpha E9 genes of the alpha-esterase cluster of D. melanogaster. A further three are also probably alpha-esterases, whereas the remaining two more closely resemble beta-esterases. Transcripts for five of the alpha-esterase genes were detected by PCR in adult midgut, consistent with a role for these enzymes in digestion and/or detoxification. Based on the tissue distribution of these transcripts, Lc alpha E7 may possibly encode the esterase, E3, which is involved in organophosphate resistance.