Heterozygous FakCG1 enhances the ommatidial mis-patterning seen in eyes expressing RetGMR.PR. Homozygous FakCG1 causes a smaller eye due to a completely disrupted ommatidial pattern. This enhancement is reversed upon co-expression of either FakScer\UAS.T:Ivir\HA1 or FakY430F.Scer\UAS under the control of Scer\GAL4GMR.PU.
The retinas of pupae (42 hours after pupal formation) expressing RetGMR.PR in a homozygous FakCG1 mutant background lack the hexagonal array and identifiable ommatidial units. Numerous ct-positive cone cells are seen. Some bristle cells and a few cells recognisable as primary pigment cells remain, but there are no detectable cells with the appearance of normal interommatidial cells. Ommatidial units with extranumerary cone cells are also seen at early stages of development (4 hours after pupal development). Eye discs contain normal number of photoreceptors, albeit some clusters have rotation defects.
Expression of RetGMR.PR partially suppresses the reduction in eye size seen in flies expressing hidGMR.PG. This suppression is partially reversed when FakScer\UAS.T:Ivir\HA1 is expressed under the control of Scer\GAL4GMR.PU.