Genomic organization and characterization of the white locus of the Mediterranean fruitfly, Ceratitis capitata

An similar to 14-kb region of genomic DNA encoding the wild-type white eye (w(+)) color gene from the medfly, Ceratitis capitata has been cloned and c haracterized at the molecular level. Comparison of the intron-exon organiza tion of this locus among several dipteran insects reveals distinct organiza tional patterns that are consistent with the phylogenetic relationships of these flies and the dendrogram of the predicted primary amino acid sequence of the white loci. An examination of w(+) expression during medfly develop ment has been carried out, displaying overall similarity to corresponding s tudies for white gene homologues in Drosophila melanogaster and other insec ts. Interestingly, we have detected two phenotypically neutral allelic form s of the locus that have arisen as the result of an apparently novel insert ion or deletion event located in the large first intron of the medfly white locus. Cloning and sequencing of two mutant white alleles, w(1) and w(2), from the we,wp and M245 strains, respectively, indicate that the mutant con ditions in these strains are the result of independent events-a frameshift mutation in exon 6 for w(1) and a deletion including a large part of exon 2 in the case of w(2).