A novel eye morphology induced by a P element in somatic tissue of Drosophila melanogaster

We found a specific eye morphology designated as Square, which is induced when some Drosophila melanogaster strains harboring P elements are crossed with the Δ2-3 strain carrying a modified P element, P[ry⁺, Δ2-3], which produces transposase in somatic tissue. This phenotype was dominant and also induced in the reciprocal crosses. Square was induced when the Δ2-3 strain was crossed with Q and M′ strains such as the sn^w (M) strain carrying three small P elements but not with P strains. Inheritance of Square was also tested and its phenotype was not transmitted to the next generation. These results suggest that Square is caused by the transposition of P elements in somatic cells.