Phospholipid composition and metabolism in the embryonic chick lens

Abstract

This study compares the phospholipids of lens epithelial cells with those of lens fibers in 6-day-old embryonic chicks, in order to determine whether changes in phospholipid composition or metabolism are associated with lens fiber differentiation. Several differences are apparent. The total amount of phospholipid in an average lens fiber cell is three to four times greater than that in an average epithelial cell. The relative sphingomyelin concentration in the lens fibers (6%) is greater than that in the lens epithelial cells (less than 1%), although the phospholipid compositions are otherwise similar. In 32P incorporation studies, the proportion of radioactivity incorporated into phosphatidic acid is 10 times greater in the lens fibers than in lens epithelial cells; phosphatidylinositol displays a high rate of 32P incorporation in both lens cell populations. The observed differences in phospholipid composition and metabolism may be related to alterations in the plasma membrane associated with the early stages of lens fiber differentiation.