Ends-out gene targeting, using P{FRT(Obp57e.KO.Scer\SceI.RS)} as the donor template, has resulted in the precise deletion of the Obp57d and Obp57e genes. The w^+* marker gene that was present in the template has been removed using P1cre, leaving only 34bp of the loxP sequence in place of the Obp57d and Obp57e genes.

Df(2R)Obp57d-e^KO females prefer hexanoic acid in an olfactory trap assay.

Df(2R)Obp57d-e^KO females seem to prefer lower concentrations of hexanoic acid than control flies in an oviposition site-preference assay, although the difference is not statistically significant.

D.melanogaster females carrying P{simObp57d-e.M} (containing both Dsim\Obp57d^tMa and Dsim\Obp57e^tMa) in a Df(2R)Obp57d-e^KO background avoid hexanoic acid in an oviposition site-preference assay, as wild-type D.simulans females do. The response of these flies to octanoic acid is not significantly different from that of the D.melanogaster control strain.

D.melanogaster females carrying P{simObp57d-e.M} (containing both Dsim\Obp57d^tMa and Dsim\Obp57e^tMa) in a Df(2R)Obp57d-e^KO background do not avoid hexanoic acid in an olfactory trap assay, in contrast to wild-type D.simulans females which do avoid it.

D.melanogaster females carrying P{secObp57d-e.M} (containing both Dsec\Obp57d^tMa and Dsec\Obp57e^tMa) in a Df(2R)Obp57d-e^KO background prefer high concentrations of octanoic acid in an oviposition site-preference assay, as wild-type D.sechellia females do.

D.melanogaster males and females carrying P{secObp57d-e.M} (containing both Dsec\Obp57d^tMa and Dsec\Obp57e^tMa) in a Df(2R)Obp57d-e^KO background do not prefer hexanoic acid in an olfactory trap assay, in contrast to wild-type D.sechellia animals.