498 IX. CAROTENOIDS AND VITAMINS A 



to the ripening eggs. Both males and females of Cyclopterus lumpus 

 mobilize astaxanthin from the liver to the flesh and skin during the sum- 

 mer spawn. ^^^ 



The fishes as a class have the ability to store the largest proportion of 

 vitamin A per unit of liver of any of the vertebrates. It is known that the 

 Atlantic cod {Gadus callarius) can convert carotene to vitamin A, but that 

 it can also absorb substantial amounts of the carotenoids unchanged. '^^^ 

 It seems reasonable to postulate that much of the preformed vitamin A in 

 fish livers does originate from carotenes. 



Exceedingly wide variations exist in the amount of vitamin A found in 

 different species. Thus, Rosenberg^ listed values for the common fishes 

 ranging from a low value of 65 I.U./g. for the haddock {Gadus aeglefinus) 

 to a high level of 600,000 I.U./g. for black sea-bass {Stereolepis gigas). 

 The liver oil of the cod (Gadus morrhua) is recorded as having a mean of 

 600 I.U./g. while at least eleven species have levels between 25,000 and 

 80,000 I.U./g., and four others levels between 120,000 and 300,000 I.U./g. 



In the case of freshwater fishes, a variable proportion of the vitamin Ai 

 is replaced by vitamin A2. Heilbron, Gillam, and Morton^^- were the first 

 to call attention to the aberrant reaction of certain fish liver oils to anti- 

 mony trichloride, although they did not realize that it occurred because 

 another form of vitamin A was present. The credit for this concept should 

 go to Edisbury, Morton, and Simpkins;^^* they made the suggestion that 

 the compound be called vitamin A2. Almost simultaneously, Lederer 

 and Rosanova^^^ discovered the presence of a large proportion of vitamin A2 

 in liver oils from Russian freshwater fishes, by making use of the same 

 aberrant antimony trichloride reaction. Although the occurrence of vita- 

 min A2 in freshwater fishes is universal, the proportion of vitamin Ai con- 

 tained along with it is subject to wide variations. Thus, the highest pro- 

 portion of vitamin A2 : vitamin Ai is found in the carnivorous fishes such as 

 the pike (Esox lucius), the pike perch or sander (Lucioperca sandra), the 

 European freshwater perch {Perca fliwiatilis) , and the wels or European cat- 

 fish (Silurus glanis)}^^ A considerably lower vitamin A2: vitamin Ai 

 ratio was found to obtain in omnivorous fishes such as the bream (Abramis 

 brama), the carp (Cyprinus carpio) and the tench {Tinea tinea). Lower 



"2 I. M. Heilbron, A. E. Gillam, and R. A. Morton, Biochem. J., 25, 1352-136C 

 (1931). 



"3 J. R. Edisbury, R. A. Morton, and G. W. Simpkins, Nature, I40, 234 (1937). 



"4 E. Lederer and V. A. Rosanova, Biokhimiija, 2, 293-303 (1937); Chem. Abst., 31, 

 5105 (1937). 



^^^ R. A. Morton, The Application of Absorption Spectra to the Study of Vitamins, 

 Hormones, and Coenzymes, 2nd. ed., Jarell, Ash, Boston, 1942. 



