A suggested hereditary mechanism for visual pigments of chars (Salvelinus spp.).

Abstract

A RECENT investigation (Munz, F. W., unpublished results) has shown that salmonid fishes of the genus Salvelinus have several different visual pigments. The methods used have been fully described elsewhere1. Retinae of dark-adapted animals were extracted with aqueous digitonin solution and then tested for homogeneity of the photosensitive pigment by the method of partial bleaching with coloured light2. Brook char, Salvelinus fontinalis (Mitchill), and Dolly Varden, S. malma (Walbaum), have the same visual pigments as are characteristic of Pacific salmon and of trout1. These are a retinene1 pigment with λmax 503 ± 1 mµ and the corresponding retinene2 pigment (λmax 527 ± 1 mµ). The arctic char, S. alpinus (L.), has a retinene1 pigment with λmax 509 ± 2 mµ; the single extract which was examined contained no retinene2 pigment. The lake char, S. namaycush (Walbaum), has a retinene1 pigment with λmax 512 ± 1 mµ. Some individuals of this species also possess the corresponding retinene2 pigment (λmax about 545 mµ,). Thus, in species of this genus, retinene1 pigments having three distinct maxima have been characterized. These maxima represent specific differences in the nature of the ‘opsin’, as the protein moiety of a visual pigment is usually called2.