Age-related changes in the visual pigments of the white sturgeon (Acipenser transmontanus)

Using in situ microspectrophotometry, the spectral absorbance characteristics of the photoreceptors in the retinas of larval, juvenile, and adult white sturgeon (Acipenser transmontanus) were determined. The adult has one type of rod, containing a visual pigment with maximum spectral absorbance (λmax) near 540 nm. There are three types of cones, morphologically identical but distinguished from one another by containing either a blue-sensitive (λmax 464 nm), green-sensitive (λmax 531 nm), or red-sensitive (λmax 605 nm) visual pigment. Juvenile sturgeon have visual pigments similar to those of the adult. However, no evidence could be found for the presence of either blue-sensitive or red-sensitive cones in larval white sturgeon through the age of 10 weeks. Larval sturgeon up to about 10 weeks yielded only green-sensitive rods and cones. The absence of red-sensitive cones in the larvae, and their presence in older fish, was confirmed by the use of 4,4′-diisothiocyanato-stilbene-2,2′-disulfonic acid, a fluore...