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

1 Centre d'Ecologie et Physiologie Energétiques, Centre National de la Recherche Scientifique, Associé à l'Université Louis Pasteur, 67087 Strasbourg, France; and 2 Avian Science Research Centre, Scottish Agricultural College, Ayr KA6 5HW, United Kingdom This study examines the transfer of lipids from the yolk to the embryo of the king penguin, a seabird with a high dietary intake of n-3 fatty acids. The concentrations of total lipid, triacylglycerol (TAG), and phospholipid (PL) in the yolk decreased by ~80% between days 33 and 55 of development, indicating intensive lipid transfer, whereas the concentration of cholesteryl 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 contained high amounts of C 20-22 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 plasma and liver contained high proportions of 22:6(n-3) (~15% in plasma 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, respectively, abundant and deficient in the yolk, undergo biomagnification during transfer to the embryo. docosahexaenoic acid; arachidonic acid; yolk sac membrane