Photopigment conversions expressed in pupil mechanism of blowfly visual sense cells

Rapid photopigment conversions in blowfly visual sense cells consequences for receptor potential and pupillary response

“…Comparing the electrophysiological and optical measurements, which were performed in the same set-up under identical conditions it may be coneluded that pigment migration is directly dependent on the existence of a membrane depolarization, when maintained for a sufficiently long time. Electrophoresis as the physical cause of retinular cell pigment migration was proposed by Stavenga (1971; see also Stavenga et al, 1975) but questioned by Miller and Cawthon (1974) (see Miller, 1975;Olivo and Larsen, 1978). The physical forces underlying pigment migration clearly deserve further investigation.…”

Visual pigment processes and prolonged pupillary responses in insect photoreceptor cells

“…The analogy with the case of prolonged depolarizing afterpotentials (PDA) recorded with intracellular electrodes (e.g., Hochstein et al, 1973;Hamdorf and Razmjoo, 1977) is obvious (Stavenga et al, 1975). Unsatisfactory in the analysis of the prolonged pupillary responses is the variability of the time course of the phenomenon among specimens as was also observed for the PDA in barnacle (Lantz et al, 1977).…”

“…Rhodopsins studied so far, which have extreme absorption at a longer wavelength than the latter value invariably have a hypsochromic shifted metarhodopsin (Goldsmith, 1972). In view of the principle of rapid dark adaptation due to photoregeneration by light leaking through the red screening pigments a bathochromic shifted metarhodopsin is very advantageous (Stavenga et al, 1973(Stavenga et al, , 1975Stark, 1975;Cosens, 1979).…”

“…However, in the latter family the dorsal eye of males contain screening pigment translucent for longerwavelength light, whereas the ventral eye has a dense dark red-brown screening pigment. It thus was argued that shorter wavelength receptors were present in the dorsal eye of simuliids, so that screening pigment and visual pigment are tuned (Kirschfeld and Wenk, 1976) similarly as was clarified for the blowfly (Stavenga et al, 1973(Stavenga et al, , 1975). Yet, it is now convincingly demonstrated that dorsally instead of a shorter wavelength receptor a longer wavelength receptor exists in the eyes of male syrphids.…”

“…This feature and the possibility to induce a rapid opening with red light (Fig. 2b; see also Stavenga et al, 1975) clearly indicates that prolonged pupillary responses occur when a substantial number of visual pigment molecules is put into the metarhodopsin state. A similar conclusion can be derived in the case of butterflies, although visual pigment properties are quite different there.…”