The overall architecture of the retina and lamina of the eye is not altered in homozygotes.
e1/e1 mutants do not show on or off transients in response to light in electroretinogram recordings (ERGs) and have reduced phototaxis. Mosaic flies with homozygous e1/e1 photoreceptors (but elsewhere heterozygous) show ERGs and phototaxis similar to wild type.
e1 mutants are defective in carcinine synthesis.
Photoreceptor terminals in e1 mutants exhibit a reduced number of synaptic vesicles. The density of these synaptic vesicles is approximately 75% of wild-type.
e1 flies do not exhibit ON and OFF transients in ERG recordings of the laminar LMC neurons at the onset and end of light stimulation.
Approximately 40% of HdcJK910 mutants show no visual alert response (to a moving block, than in wild-type freezes fly movement). Approximately 20% exhibit a delayed response, and a brief-pause response is observed in 24% of flies.
e1/eTW1 flies show a dark pigmented trident pattern on the thorax.
There are fewer synaptic vesicles per R1-R6 photoreceptor terminal in e1 mutants than in wild type.
A stripe of dark pigment seen in wild-type adult females near the posterior edge of abdominal segments A2-A6. e1 mutants retain a distinct pugment stripe and the cuticle anterior to the stripe is much darker than wild-type. In the thorax and wings, wild-type flies have a uniform colour. In e1 mutants the thorax and wings become more darkly pigmented, and new pigmentation patterns are seen.
When e1 is combined with either rhove-1 or Vno1, in which wing veins are truncated or eliminated, ectopic melanin only develops in proximity to the veins that remain.
N-Β-alanyldopamine levels are drastically reduced in homozygous flies compared to wild-type, while dopamine levels are elevated approximately twofold. When e1 pharate adult tissue is incubated with dopamine in vitro, the extent of inducible pigmentation of body cuticle, hairs and bristle sockets resembles that of wild-type, while pigmentation of the bristle shafts is significantly reduced.
A large fraction of homozygotes are arrhythmic with respect to locomotor activity when kept in constant darkness at 24oC, and the average signal-to-noise ratio (SNR) is lower than wild-type. Heterozygotes have intermediate SNR values between homozygotes and wild-type, indicating that their rhythmicity is not completely normal. Homozygotes usually show disorganised bouts of activity when transferred from a light-dark cycle to constant darkness. At 20oC, most homozygotes have weak rhythmicity or are arrhythmic, at 28oC, most homozygotes have significant periodicity. The circadian period tends to be shorter at 20oC and longer at 28oC. Some homozygotes have extremely weak rhythms under a light-dark cycle. Hemizygous e1/Df(3R)e-BS2 or e1/Df(3R)e-N19 flies show variable rhythmicity in constant darkness at 20oC and do not synchronise normally to light-dark cycles, similar to homozygotes. In contrast to homozygotes however, they do not show short-period rhythms at 20oC. norpA7 and norpA36 partially suppress the arrhythmicity of some homozygous e1 flies. The eclosion rhythm is normal.