STORAGE OF CAROTENOIDS AND OF VITAMINS A 501 



the skin of the European, brown, grass frog {Rana temporaria), the edible 

 green water-frog {R. esculenta), and the leaf-frog {Hyla arbor ea)f^'^ 

 Rand^''^ confirmed these results and reported that carotenoids also occur 

 in the liver, kidneys, lungs, ovaries and eggs, testes, and fat bodies of both 

 summer and winter frogs. The highest carotenoid content occurs in the 

 liver.^*^ Zechmeister and Tuzson" were able to prepare pure ;S-carotene, 

 a small amount of a-carotene, zeaxanthin and lutein from the livers of R. 

 esculenta. Ganguly and co-workers-" demonstrated the presence of both 

 carotenes and carotenols in the ovaries, as well as in the livers of R. escu- 

 lenta; however, carotenoids were absent from the blood. Zechmeister^*^ 

 is of the opinion that the frog is in the same class as man (Group A) in- 

 sofar as carotenoid metabolism is concerned, since it exercises little or no 

 selection between hydrocarbon and alcoholic types of carotenoids. Ac- 

 cording to Morton and Rosen,^^° the carotenoids in R. temporaria are dis- 

 persed throughout the various tissues, but quite unevenly; the storage of 

 carotenoids in the ovaries is so large that it results in a markedly higher 

 storage of these pigments, in the females as a whole than in the males. A 

 marked seasonal variation in tissue carotenoid concentration was likewise 

 found in the frogs; however, the carotenoid reserves were retained in the 

 liver during hibernation and inanition. 



Frogs also have considerable stores of vitamin A. Morton and Rosen^^" 

 reported the presence of vitamin A in the eyes of tadpoles of the species, 

 R. temporaria. In the adult frog, about 85% of the vitamin A was present 

 as the ester in the liver, while the remaining 15% was equally divided be- 

 tween the kidneys and the eyes. A higher proportion of vitamin A was 

 found in the kidneys of frogs than is present in mammalian kidneys. 

 The vitamin A was not ingested as such, but originated from the break- 

 down of carotene. Wald^^s reported that tadpoles of the North American 

 bullfrog (R. cateshiana) contain vitamin A2, while only vitamin Ai occurs 

 in this species after metamorphosis. However, Collins and co-workers^^^ 

 reported that vitamin Ai is the sole type of vitamin A in the tadpoles of R. 

 esculenta and R. temporaria. Both carotenoids and vitamin A have been 

 isolated in salamanders. Thus Beatty^^^ identified |S-carotene and unes- 

 terified xanthophylls in the body proper (Avithout viscera) of the olm, a 

 pale or white, blind, aquatic, tailed eel-like salamander, with blood-red gills 

 {Proteus anguinus), obtained from dark underground caves. /3-carotene 



"8 C. Rand, Biochem. Z., 281, 200-205 (1935). 



6« O. Brunner and R. Stein, Biochem. Z., 282, 47-50 (1935). 



»" R. A. Morton and D. G. Rosen, Biochem. J., 45, 612-627 (1949). 



6" F. D. Collins, R. M. Love, and R. A. Morton, Biochem. J., 53, 632-636 (1953). 



5" R. A. Beattv, J. Exptl. Biol., 18, 144-152 (1941). 



