Isolation and characterization of the xanthine dehydrogenase gene of the Mediterranean fruit fly, Ceratitis capitata

Xanthine dehydrogenase (XDH) is a member of the molybdenum hydroxylase fami ly of enzymes catalyzing the oxidation of hypoxanthine and xanthine to uric acid. The enzyme is also required for the production of one of the major D rosophila eye pigments, drosopterin. The XDH gene has been isolated in many species representing a broad cross section of the major groups of living o rganisms, including the cDNA encoding XDH from the Mediterranean fruit fly Ceratilis capitala (CcXDH) described here. CcXDH is closely related to othe r insect XDHs and is able to rescue the phenotype of the Drosophila melanog aster XDH mutant, rosy, in germline transformation experiments. A previousl y identified medfly mutant, termed rosy, whose phenotype is suggestive of a disruption in XDH function, has been examined for possible mutations in th e XDH gene. However, we find no direct evidence that a mutation ill the CcX DH gene or that a reduction in the CcXDH enzyme activity is present in rosy medflies. Conclusive studies of the nature of medfly, rosy mutant will req uire rescue by germline transformation of mutant medflies.