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 )

• Published in: Biochemistry and Cell Biology
• Main Authors: Ball, Mark D., Nizzi, Christopher P., Furr, Harold C., Olson, James A., Oftedal, Olav T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1992
• Subjects: Cell Biology; Molecular Biology; Biochemistry; Cystophora cristata; Harp Seal; hooded seal; Phoca groenlandica
• Online Access: http://dx.doi.org/10.1139/o92-123; http://www.nrcresearchpress.com/doi/pdf/10.1139/o92-123

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 20:1, 20:4, 20:5, and 22:6 in unusually large amounts. Retinyl esters tended to be richer than whole-liver lipids in 20:5 + 22:6, whereas whole-liver lipids were richer in 18:0 and 18:2. 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 18:0 and 20:1 in the retinyl esters rose and that of 14:0 + 16:1 and 20:4 fell. Concomitantly, in their mothers, the proportion of 20:4 increased but that of 16:0 and 18:0 decreased.Key words: fatty-acid composition, pinniped liver, retinyl esters, vitamin A.