In the absence of the amber suppressor (tRNA:Y1:22FaDtT.Su+) mild photoreceptor cell defects are observed: light transmission spots are blurred or missing. In the presence of tRNA:Y1:22FaDtT.Su+ the extent of photoreceptor cell defects is enhanced. Photoreceptor cell bodies and their associated rhabdomere specialisations are completely absent while the accessory ommatidial cells remain forming an empty honeycomb-like structure. Expression arrests photoreceptor cell development by 48 hours of pupal development. The larval photoreceptor nerve is also affected, ranging from being greatly reduced in diameter and broken at multiple sites to being ablated. Expression of a functional toxin does not reduce viability. Examination of the adult optic ganglia reveals the formation and maintenance of normal optic ganglia does not appear to require the continuous presence of intact larval or retinula photoreceptor cells.
