Three visual pigments in Deilephila elpenor (Lepidoptera, Sphingidae)

"Selective irradiation of digitonin extracts (pH 6.1) from dark-adapted eyes of the Sphingid moth Deilephila elpenor revealed three visual pigments with λ_max at about 345, 440 and 520 nm. From the reaction of the chromophoric group with hydroxylamine it is concluded that these pigments are based on retinaldehyde, and therefore can be classed with rhodopsins. At −15 °C, each of the rhodopsins can completely (P 520) or partially (P 440 and P 345) be converted by light to acid metarhodopsin absorbing maximally at 480 ± 10 nm, which decay at room temperature to retinaldehyde and protein moiety. Spectrophotometric measurements on isolated retinae (pH 7.4) indicate that the metarhodopsins, in contrast to the findings on extracts, are thermostable in the photoreceptor membrane at room temperature. The results are compared with electrophysiological and microspectrophotometrical data. The different properties of the metarhodopsins in detergent solution and in the isolated retina are discussed."