Single and multiple visual pigments in deep-sea fishes

Abstract

The visual pigments in the retinal rods of 17 species of deep-sea fish were examined by microspectrophotometry or visual pigment extract spectrophotometry. In 15 species single visual pigments were found with peak sensitivities between 470 and 490 nm, typical of deep-sea fishes. However, in one species, Stylephorons coniatus, two visual pigments were found with X mix values at 470 and 481 nm. In another species, Scopelardmsanalis, three visual pigments were found with mean X values of 444, 479 and 505 nm. The short-wave pigment of this species was found both in main and accessory retinae. It was present both in single rods and in outer segments which had the most long-wave sensitive pigment in their distal parts. It is argued that these two-pigment rods are in the process of changing their visual pigment from a 'juvenile' VP505 pigment to an 'adult' VP444 pigment. The VP479 was found only as a single pigment in rods in the accessory retina.

The visual pigments of a deep-sea teleost, the pearl eyeScopelarchus analis

“…The accessory retina contains all three pigments, with the 505 and 444·nm pigments again found together in the same outer segments. In both cases, sequential scans at 8·m intervals along the outer segment have demonstrated that the 505·nm pigment is always located at the distal end and the 444·nm pigment at the proximal end (Partridge et al, 1992), with an abrupt transition between the two. The accessory retina also contains receptors that solely express the 444 or 479·nm…”

“…In contrast therefore to most deep-sea fish that have a rod-only retina (Douglas et al, 2003), cone photoreceptors are retained in Scopelarchus sp. Microspectrophotometry of photoreceptor outer segments from the main and accessory retinae of S. analis has identified three visual pigments with max values at 444, 479 and 505·nm (Partridge et al, 1992). The main retina contains only the 505 and 444·nm pigments, with both present in the same outer segments.…”

“…These observations were made on a single fish that was considered to be in the process of maturing from a shallow-living juvenile to a deep-sea adult, and the replacement of the 505·nm with the 444·nm pigment in the same photoreceptors was considered to be a reflection of this maturation (Partridge et al, 1992). A similar situation has been shown to exist in rod photoreceptors during the metamorphosis of the common eel Anguilla anguilla, where one rod pigment is replaced by a second with a max that is also shifted to a shorter wavelength (Hope et al, 1998).…”

The effect of elevated hydrostatic pressure on the spectral absorption of deep-sea fish visual pigments

“…In a darkroom, and working under dim red light, retinae were removed from hemisected eyes and either their visual pigments were extracted immediately and then frozen, or the retinae were frozen in 20·mmol·l -1 Pipes-buffered saline (450·mOsm·kg -1 , pH·7.3) for later extraction. Visual pigments were extracted from both fresh and frozen material in an identical manner using the detergent n-dodecyl ␤-D-maltoside, as detailed elsewhere (Partridge et al, 1992;Douglas et al, 1995 N is the number of individuals of each species measured. Capture depths were calculated as the medians of all data for minimum capture depth available for each species at http://www.fishbase.org.…”

Pineal organs of deep-sea fish: photopigments and structure

“…K. Bowmaker and H.-J. Wagner a λmax of rod pigments taken from Douglas and Partridge (1997) and Partridge et al (1988Partridge et al ( , 1989Partridge et al ( , 1992. The data are from extracts and/or microspectrophotometry and may vary by 1-2·nm.…”