Characterization of two alcohol dehydrogenase (Adh) loci from the olive fruit fly, Bactrocera (Dacus) oleae and implications for Adh duplication in dipteran insects
Gn. Goulielmos et al., Characterization of two alcohol dehydrogenase (Adh) loci from the olive fruit fly, Bactrocera (Dacus) oleae and implications for Adh duplication in dipteran insects, J MOL EVOL, 52(1), 2001, pp. 29-39
We report the cloning and structural characterization of two Adh loci of th
e olive fruit fly, Bactrocera oleae, Each of the two genes, named Adh1 and
Adh2, consists of three exons and two introns for a total length of 1981 an
d 988 nucleotides, respectively. Their deduced amino acid sequences of 257
and 258 residues exhibit a 77% identity and display the characteristics of
the insect ADH enzymes, which belong to the short-chain dehydrogenases/redu
ctases family. The Adh genes of B. oleae are compared to the two genes of t
he Mediterranean fly, Ceratitis capitata, the only other species of the Tep
hritidae family in which the Adh genes have been studied. On the basis of a
mino acid divergence the four genes form two clusters each containing one g
ene from each species, as expected if there was one duplication event befor
e speciation. On the basis of nucleotide sequence the four sequences form t
wo clusters each containing the two sequences from the same species, as exp
ected if there was a separate duplication event in each species, To help de
cide between the two alternatives, we compared at both the amino acid and D
NA level the Adh genes of five Drosophila species that are known to carry t
wo such genes and observed that, with only one exception at the amino acid
level, conspecific loci cluster together. We conclude that the information
we have at present does not allow a firm choice between the hypothesis of a
single duplication event that occurred before the split of Bactrocera and
Ceratitis from their common ancestor and the hypothesis of two independent
duplication events, one in each of the two genera.