Transfer of n-3 and n-6 polyunsaturated fatty acids from yolk to embryo during development of the king penguin

This study examines the transfer of lipids from the yolk to the embryo of t he king penguin, a seabird with a high dietary intake of n-3 fatty acids. T he concentrations of total lipid, triacylglycerol (TAG), and phospholipid ( PL) in the yolk decreased by similar to 80% between days 33 and 55 of devel opment, indicating intensive lipid transfer, whereas the concentration of c holesteryl ester (CE) increased threefold, possibly due to recycling. Total lipid concentration in plasma and liver of the embryo increased by twofold from day 40 to hatching due to the accumulation of CE. Yolk lipids contain ed high amounts of C20-22 n-3 fatty acids with 22:6(n-3) forming 4 and 10% of the fatty acid mass in TAG and PL, respectively. Both TAG and PL of plas ma and liver contained high proportions of 22:6(n-3) (similar to 15% in pla sma and >20% in liver at day 33); liver PL also contained a high proportion of 20:4(n-6) (14%). Thus both 22:6(n-3) and 20:4(n-6), which are, respecti vely, abundant and deficient in the yolk, undergo biomagnification during t ransfer to the embryo.