Phospholipid composition and [14C]glycerol incorporation into glycerolipids of toad retina and brain.

The phospholipid composition as well as the in vivo [14C]glycerol uptake in lipids was found to be similar in the toad brain and retina. The choroid lipid labeling was markedly different. An in vitro time-course study of [14C]glycerol incorporation in toad retina lipids disclosed that under the conditions of these experiments: (1) retina is able to rapidly synthesize phosphatidic acid from the radioactive precursor; (2) the sequence phosphatidic acid-diacylglycerol-triacylglycerol operates; (3) a high rate of phosphatidylinositol de novo biosynthesis takes place; (4) phosphoglycerides of choline and of ethanolamine are also heavily labeled after a lag period; (5) in vivo labeling profiles resembled those obtained in vitro mainly regarding phosphatidylinositol biosynthesis; and (6) the presence of glycerol kinase in the CNS is suggested.