Drosophila locus with gene-dosage effects on rhodopsin

Abstract

Mutations that decrease the amplitude of the prolonged depolarizing afterpotential (PDA) in D. melanogaster were previously shown to have reduced rhodopsin content in the rhabdomeres of photoreceptor cells. Here, a genetic analysis of a class of 3rd chromosome PDA-defective mutants localized the ninaE locus to the salivary band region 92A-B. In flies with only 1 copy of this region instead of the normal 2 copies, and in ninaE heterozygotes, the rhodopsin content of the major class of photoreceptors is reduced. Three doses of this region increase the rhodopsin content of these photoreceptors. These characteristics of the ninaE locus are expected of the structural gene encoding the major species of opsin in the Drosophila compound eye.