Morphological Defects in ora^jk84 Photoreceptors Caused by Mutation in R1-6 Opsin Gene of Drosophila

Abstract

The Drosophila mutant, ora^JK84, lacks rhabdomeres in the major (R1-6) class of photoreceptors because these rhabdomeres rapidly degenerate in young flies. Genetic analysis reveals that ora^JK84 actually contains two mutations (a ninaE and an on allele) that affect the visual process. The mutation in ort appears to have no effect on photoreceptor structure. The other mutation occurs within the ninaE gene, which encodes the species of rhodopsin found in the R1-6 class of photoreceptors. Our analysis shows that this mutation is responsible for R1-6 rhabdomere degeneration in ora^JK84 mutants. We also examined a ninaE mutant, denoted ninaE^o117, that produces no ninaE transcript. The morphological phenotype observed in ninaE^o117 is similar to that seen in ora^o117 mutants. We conclude that rhodopsin plays a vital role in maintaining photoreceptor structure in Drosophila.

Key Words:

• visual system
• Rhodopsin
• rhabdomere degeneration
• ninaE mutant
• ora transientless mutant