516 IX. CAROTENOIDS AND VITAMINS A 



Although there is no question that animals in the above group can be 

 readily separated from the other group because of the minimum quantities 

 of jS-carotene stored, there is still some evidence that the small amount of 

 chromogenic material in the liver consists of carotenoids. Beadle et al}^^ 

 did prove that the yellow fat sometimes encountered in pigs did not con- 

 tain carotenoids. However, Ganguly et alr^'^ were able to prove by une- 

 quivocal methods that the small amount of chromogenic material present 

 in the livers of rats after the administration of carotene was, in fact, all- 

 ^mws-/3-carotene. Thus, after saponification of the livers, followed by ex- 

 traction with solvent and chromatography on an alumina column, it was 

 found that a 4% acetone eluate was colored. The fact that this was ^- 

 carotene was proved by comparing the extinction with pure ,S-carotene in 

 carbon disulfide, benzene, and hexane, as well as by the demonstration 

 that a mixed chromatogram with pure /S-carotene gave a single bond with 

 an unchanged extinction curve. ^^ The amount of all-<rans-/3-carotene in 

 rat livers was found to average 2.1 Mg-/g- liver. 



In view of the above results, the author is forced to conclude that the 

 difference between the carotene metabolism in the carotenoid accumulators 

 and in those which do not store these substances is quantitative rather than 

 qualitative. Actually, small amounts of carotene do escape the intestinal 

 barrier to gain entrance to the body, but the "carotenase" mechanism is 

 sufficient to limit the quantity of carotene which is not broken down. If 

 this concept is accepted, it would provide a possible explanation for the 

 j8-carotene in the retina of the pig, when no trace of the carotenoid could 

 be demonstrated in the blood or liver of this species. 



Moore and Payne^'*^ reported a vitamin A value of 45 I.U./g. of liver in 

 the pig. The livers of pigs had more vitamin A in the summer than in the 

 winter. This was found to be similar to the situation in cows, but did not 

 apply to sheep. Williams^^^ furnished the following data on the idtamin A 

 content in the carcasses of several species (I.U./kg.) and the per cent of the 

 total vitamin A in the liver: monkey, 6,150, 67%; guinea pig, 29,500 and 

 2,040, 92% and 10%; rabbit, 1,840 and 2,500, 35% and 21%; gopher, 

 11,800, 67%; rat, 24,000, 97%; cat, 2,100 and 56,400, 24% and 92%; 

 and dog, 7,925, 21,000 and 27,500, 19%, 16% and 43%. One cannot make 

 many deductions from the above data except that wide variations obtain 

 in the amount of vitamin A present, and in the proportion in the liver. 

 Since the liver is the organ in which variable amounts of vitamin A are 

 sorted, one would expect that the proportion in this organ would be highest 



663 B. W. Beadle, O. H. M. WUder, and H. R. Kraybill, /. Biol. Chem., 175, 221-229 

 (1948). 



