Does retinol serve a sensitizing function in insect photoreceptors?
Spectral sensitivity of the dorsal compound eye of Simuliid males (Nematocera) shows a maximum in the u.v. at 340 nm, and a shoulder or second, smaller maximum around 430 nm. The visual pigment--based on retinal and therefore a rhodopsin--has its absorption maximum at 430 nm. The 340 maximum is due to a sensitizing pigment that transfers energy to the visual pigment. The properties of the Simuliid-photoreceptor hence are similar to most of the photoreceptors in higher flies (Musca, Calliphora, Drosophila), that also have a u.v.-absorbing sensitizing pigment. The difference is that in Simuliids the sensitizing pigment is not 3-hydroxyretinol as in the higher flies but a different substance, most likely retinol.
D000818:Animals; D005260:Female; D008297:Male; D010786:Photoreceptor Cells / Q000502:physiology*; D012168:Retinal Pigments / Q000502:physiology*; D012843:Simuliidae / Q000502:physiology*; D013053:Spectrophotometry; D014466:Ultraviolet Rays; D014801:Vitamin A / Q000502:physiology*
D012168:Retinal Pigments; D014801:Vitamin A