Transvection at the eyes absent gene of Drosophila.

The Drosophila eyes absent (eya) gene is required for survival and differentiation of eye progenitor cells. Loss of gene function in the eye results in reduction or absence of the adult compound eye. Certain combinations of eya alleles undergo partial complementation, with dramatic restoration of eye size. This interaction is sensitive to the relative positions of the two alleles in the genome; rearrangements predicted to disrupt pairing of chromosomal homologs in the eya region disrupt complementation. Ten X-ray-induced rearrangements that suppress the interaction obey the same general rules as those that disrupt transvection at the bithorax complex and the decapentaplegic gene. Moreover, like transvection in those cases, the interaction at eya depends on the presence of normal zeste function. The discovery of transvection at eya suggests that transvection interactions of this type may be more prevalent than generally thought.