. Carotenoids, their comparative biochemistry. Carotenoids. CAROTENOIDS for Glover *' found no carotenoids in the halibut (although traces may be present in the ova)' ^ in spite of its main food being a fish, Sebastes marinuSy rich in astaxanthin. * Glover, Morton and Rosen ^^ have follovv^ed the metabolism of astaxanthin in salmon (Salmo salar) eggs. For the six weeks betw^een the fertilization of the eggs and hatching no change took place in the amount of astaxanthin. Two months after the hatching the content had decreased by 12 per cent. ; whether this drop is significant or not it is diffi
. Carotenoids, their comparative biochemistry. Carotenoids. CAROTENOIDS for Glover *' found no carotenoids in the halibut (although traces may be present in the ova)' ^ in spite of its main food being a fish, Sebastes marinuSy rich in astaxanthin. * Glover, Morton and Rosen ^^ have follovv^ed the metabolism of astaxanthin in salmon (Salmo salar) eggs. For the six weeks betw^een the fertilization of the eggs and hatching no change took place in the amount of astaxanthin. Two months after the hatching the content had decreased by 12 per cent. ; whether this drop is significant or not it is difficult to say. At hatching 92 per cent, of the total astaxanthin present was in the yolk sac. As the embryos develop there is a constant transfer of pigment from the sac to the embryo, so that a two month embryo contains 80 per cent, of the total pigment. Not only is there a transfer but the astaxanthin is esterified as it is laid down in the em- bryo. The same type of change occurs in entirely fresh water fish (see p. 207). 60 ^ 40 20. ^ Astaxanchin in coca! embryonic sysCem O Astaxanthin in yolk sac # Astaxanchin in embryo ^ 45 35 25 15 Pre-hatching period 5 0 Days 15 25 35 Posc-hatching period 45 Fig. 26.—Showing the Astaxanthin distribution in the developing salmon embryo. (After Glover, M., Morton, R. A., and Rosen, G. D. (1949) Biochem, J., 50,425). Function (a) In Photoresponses. The work of Sumner and Fox ^ 2-1 * indicates that carotenoids do play a part in photoresponses in some fish. Fundulus parvipinnis and Gillichthys mirabilis maintain their carotenoid content in different optical environments although the colours of the fish 196. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Goodwin, T. W. (Trevor Walworth). New York, Chemical Pub. Co.
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