Fatty-acyl esters of retinol (vitamin A) in the liver of the harp seal (Phoca groenlandica), hooded seal (Cystophora cristata), and California sea lion (Zalophus californianus).

ABSTRACT

The fatty-acid composition of retinyl esters in the livers of two species of phocid seal, the harp seal (Phoca groenlandica, n = 20) and the hooded seal (Cystophora cristata, n = 15), and one species of otariid seal, the California sea lion (Zalophus californianus, n = 6), was determined. Vitamin A ranged in concentration from 4 to 1024 nmol retinol/g liver for the phocids and from 381 to 979 nmol/g liver for the otariids. In most of the livers, retinyl palmitate was not the principal ester, and the palmitate + stearate + oleate trio of retinyl esters represented less than 50% of the total. In all samples, the retinyl esters contained 201, 204, 205, and 226 in unusually large amounts. Retinyl esters tended to be richer than whole-liver lipids in 205 + 226, whereas whole-liver lipids were richer in 180 and 182. Therefore, the pool of acyl donors used for the esterification of retinol may be distinct from that used for other lipids. Birth-to-weaning changes were seen only in the harp seals. In the pups, the hepatic vitamin-A concentration increased 454%, while the proportion of 180 and 201 in the retinyl esters rose and that of 140 + 161 and 204 fell. Concomitantly, in their mothers, the proportion of 204 increased but that of 160 and 180 decreased.