Transfer of Vitamins E and A from Yolk to Embryo during Development of the King Penguin (Aptenodytes patagonicus).

Since the yolk lipids of the king penguin (Aptenodytes pata-gonicus) are rich in n-3 fatty acids, which are potentially sus-ceptible to peroxidative damage, the yolk contents and yolk-to- embryo transfer of antioxidants and lipid-soluble vitamins were investigated under conditions of natural incubation in the wild. The concentration of vitamin E in the unincubated egg was 155 m g/g wet yolk, of which 88% was a -tocopherol and the rest was g -tocopherol. Vitamin A (2.9 m g/g) was present in the yolk entirely as retinol; no retinyl esters were detected. Throughout the latter half of the incubation period, vitamins E and A were taken up from the yolk into the yolk sac membrane (YSM) and later accumulated in the liver, with vi-tamin A being transferred in advance of vitamin E. In the YSM, vitamin A was present almost entirely as retinyl ester, indicating that the free retinol of the yolk is rapidly esterified following uptake. Retinyl esters were also the predominant form in the liver. The retinyl esters of the liver and YSM displayed different fatty acid profiles. At hatching, the brain contained relatively little vitamin E (4.7 m g/g) compared to the much higher con-centration in the liver (482.9 m g/g) at this stage. Ascorbic acid was not detected in the yolk but was present at a high con-centration in the brain at day 27 (404.6 m g/g), decreasing to less than half this value by the time of hatching. This report is the first to delineate the yolk-to-embryo transfer of lipid-soluble vitamins for a free-living avian species. The yolk... [ABSTRACT FROM AUTHOR]

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