Liver lipids during development.

The fatty acid composition of the major liver microsomal phospholipids has been studied during pre- and postnatal development of the rabbit. The fatty acid composition of the total lipids, phosphatidyl choline, and phosphatidyl ethanolamine from animals -6, -3, 0, +3, +6, +9, +16, and +112 days of age was determined. Fatty acid composition is similar in phosphatidyl choline and phosphatidyl ethanolamine for oleic acid at +3, +6, +9, and +16 day old animals; palmitoleic acid at +9 day old animals and linoleic acid at -6, -3, and 0 day old animals.Palmitoleic acid demonstrated a uniform decrease during early development in the total lipids and in both phosphatidyl choline and phosphatidyl ethanolamine; however, in the 112 day animal, the amount was just slightly lower than that observed for the earliest prenatal animal studied. Oleic acid decreased considerably during early postnatal development in the total lipids, phosphatidyl choline and phosphatidyl ethanolamine, but an increase in the 112 day animal was observed. Linoleic acid fluctuated considerably throughout postnatal development in the total lipids as well as in the two major phosphatides.Lecithin biosynthesis has been studied by two pathways during development of rabbit liver from -6 days to +110 days. The two pathways of lecithin biosynthesis were evaluated by assaying the activities of the liver enzymes choline phosphotransferase and phosphatidylmethyltransferase at different time intervals during development. The greater enzymatic activity was observed in the cholinephosphotransferase during development.