Lateral mobility of plasma membrane lipids in a molluscan egg: Evidence for an animal/vegetal polarity

Abstract

The lateral diffusion of the lipid analog C₁₄-diI (3', 3'-dihexadecylindocarbocyanine iodide) was measured in the plasma membrane of early embryos of the mollusc Nassarius reticulatus using the FPR-(Fluorescence Photobleaching Recovery) method. At almost all stages measured (from fertilized egg up to 8-cell stage) the diffusion coefficient (D) of the mobile fraction (MF) of C₁₄-diI is significantly higher in the plasma membrane of the polar lobe as compared to the plasma membrane of the animal half of the embryo. These results demonstrate the presence of an animal/vegetal polarity in the plasma membrane of the embryo of Nassarius, possibly related with the polar localization of morphogenetic factors.