title: Flies in the group Cyclorrhapha use (3S)-3-hydroxyretinal as a unique visual pigment chromophore.
abstract: In the class Insecta, retinal and 3-hydroxyretinal are used as chromophores of visual pigments, but the absolute structure of the 3-hydroxyretinal chromophore has yet to be clarified. This study investigates the chirality of 3-hydroxyretinal in the compound eyes of five representative orders of insects. In the orders Odonata, Hemiptera, Neuroptera and Lepidoptera, and suborders Nematocera and Brachycera of the Diptera, only (3R)-3-hydroxyretinal isomers were detected, but dipterans of the suborder Cyclorrhapha (higher flies) had the (3S)-11-cis enantiomer and a mixture of (3R)-all-trans and (3S)-all-trans 3-hydroxyretinal enantiomers; the ratio of the (3R) enantiomer to the sum of both enantiomers of the all-trans isomer was in the range 9-32%. Despite differences in feeding habits, including one species that is a butterfly parasite, all higher flies analysed to date share the same pattern of 3-hydroxyretinal enantiomers, making them a unique group with regard to the nature of the visual pigment chromophore.
authors.affiliation: Department of Health Science, Osaka Kyoiku University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Seki
authors.forename: K
authors.initials: K
authors.lastname: Isono
authors.forename: M
authors.initials: M
authors.lastname: Ito
authors.forename: Y
authors.initials: Y
authors.lastname: Katsuta
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004175:Diptera / Q000378:metabolism; D005123:Eye / Q000378:metabolism; D006430:Hemiptera / Q000378:metabolism; D007313:Insecta / Q000378:metabolism*; D007915:Lepidoptera / Q000378:metabolism; D012168:Retinal Pigments / Q000378:metabolism*; D012172:Retinaldehyde / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D013237:Stereoisomerism
chemical_list: D012168:Retinal Pigments; C049427:3-hydroxyretinal; D012172:Retinaldehyde