Genetic Identification and Molecular Characterization of an Eyes Absent (eya) Mutation Disrupting Compound Eye Development in Drosophila melanogaster

Background: Drosophila melanogaster has long been valued as a model organism for studying the genetics underlying tissue differentiation, especially in the context of eye development. The formation of the fly’s compound eye is orchestrated by a group of genes known as the retinal determination gene network (RDGN), which includes key transcriptional regulators such as eyeless, sine oculis, dachshund, and eyes absent (eya). Results : Through a combination of classical genetic crosses, complementation testing, and PCR-based molecular assays, we identified a mutation in Drosophila melanogaster that results in the absence of compound eye structures. Notably, other head features such as antennae remained unaffected. The inheritance pattern observed in genetic crosses was recessive. Linkage analysis indicated that the mutation was associated with markers on chromosome 2. Complementation analysis demonstrated that the mutation complemented eyeless but did not complement a known eyes absent allele, suggesting the mutation is located at the eya locus. PCR amplification of the eya genomic region produced a fragment approximately 320 base pairs smaller than that of wild type, supporting the presence of a deletion in the eya gene. Conclusions: The data identify the eyes absent allele as the primary mutation responsible for the absence of compound eyes in the affected flies. These results underscore the essential role of eya within the retinal determination gene network during eye development in Drosophila melanogaster.