Interspecific variation in the visual pigments of deep-sea fishes

Abstract

Visual pigments in the rods of 38 species of deep-sea fish were examined by microspectrophotometry. 33 species were found to have a single rhodopsin with a wavelength of maximum absorbance (lambda max) in the range 470-495 nm. Such visual pigments have absorbance maxima close to the wavelengths of maximum spectral transmission of oceanic water. 5 species, however, did not conform to this pattern and visual pigments were found with lambda max values ranging from 451 nm to 539 nm. In 4 of these species two visual pigments were found located in two types of rod. Some 2-pigment species which have unusual red sensitivity, also have red-emitting photophores. These species have both rhodopsin and porphyropsin pigments in their retinae, which was confirmed by HPLC, and the two pigments are apparently located in separate rods in the same retinal area. In deep-sea fishes the occurrence of 'unusual' visual pigments seems to be correlated with aspects of the species' depth ranges. In addition to ecological influences we present evidence, in the form of lambda max spectral clustering, that indicates the degree of molecular constraint imposed on the evolution of visual pigments in the deep-sea.

Mechanisms of wavelength tuning in the rod opsins of deep-sea fishes

“…Candidate sites for spectral tuning that are identified in the text are indicated by an asterisk. The λ max values (nm) of the rod visual pigments were measured by microspectrophotometry (Partridge et al 1988 ;Partridge 1989 ;Partridge et al 1989 ;Archer et al 1992 …”

“…laticeps (Partridge et al 1988 ;Partridge 1989 ;Partridge et al 1989). This contrasts with values of around 500 nm found in shallow living species (Lythgoe 1972) and in the eel ' freshwater ' pigment.…”

“…Rod opsins of deep-sea fish opsins A. J. Hope and others pigments consist of a membrane-bound protein (opsin) combined with a chromophore that, in almost all deepsea fishes, is the aldehyde of vitamin A1, retinal (Partridge et al 1988 ;Partridge 1989 ;Partridge et al 1989). The wavelength of peak spectral sensitivity (λ max ) of the rhodopsin visual pigment formed by an opsin and retinal is determined by the amino acid sequence of the opsin.…”

The visual ecology of a deep-sea fish, the escolar Lepidocybium flavobrunneum (Smith, 1843)

“…This length is effectively doubled to 148 mm by the presence of the tapetum. With a typical absorption coefficient k for deep-sea fishes of 0.064 mm 21 [26,27], this leads to 12e 2kl ¼ 0.9999. Thus, assuming that all layers are functional (which they may not be [28]), the banked retina of the escolar can significantly enhance the sensitivity of the eye.…”

Behavioral responses of two deep-sea fish species to red, far-red, and white light

“…Electrophysiological, morphological, and some behavioral studies have indicated that most deep-sea fishes have limited sensitivity to longer wavelengths (Partridge et al 1988, Douglas & Partridge 1997, Widder et al 2005). However, a few genera (Pachystomias, Aristostomias, and Malacosteus) in 1 family of meso-/bathypelagic fishes, are known to produce far-red bioluminescence and to have longwave visual sensitivity (O'Day & Fernandez 1974, Widder et al 1984, Bowmaker et al 1988, Partridge et al 1989, and the possibility cannot be discounted for some others (Douglas et al 2002). Widder et al (2005) demonstrated that the deep-sea fish Anoplopoma fimbria (sablefish, Anoplopomatidae) responded to red light in situ even though this species has a maximum visual sensitivity at 491 nm (Ali & Wagner 1975).…”