Homozygous gek^NP5192 mutants exhibit highly penetrant R cell targeting phenotypes.

In homozygous gek^NP5192 and transheterozygous gek^NP5192/Df(2R)e03819-f02302 animals R cell axon fascicles above the lamina plexus are occasionally clumped and the lamina plexus appears broken and varies in thickness. This phenotype is seen in all brains examined. Additionally, occasional bundles of axons were observed extending into the medulla that are thicker than usual. Organisation of the lamina neurons in homozygous gek^NP5192 eye discs is normal. Glial cells migrate normally into the lamina and are only subtly disorganised, likely a consequence of the clumping of R1-R6 terminals in the lamina plexus.

In homozygous gek^omb1080/gek^NP5192 third instar larvae R cell axon fascicles above the lamina plexus are occasionally clumped and the lamina plexus appears broken and varies in thickness. This phenotype is seen in all brains examined. Additionally, occasional bundles of axons were observed extending into the medulla that are thicker than usual.

Homozygous gek^NP5192 photoreceptor clones extend out of the retina into the brain, fasciculate normally and stop in the lamina. However, once in the lamina, mutant photoreceptors often make errors in columnar targeting, making projections to one or more incorrect target cartridges in addition to the correct target, or failing to extend at all.