Isolation and characterization of Plasma membranes from Fucus serratus eggs

Abstract

Eggs of the brown alga Fucus are large, sperical cells which lack a cell wall. Previous studies showed that a membrane vesicle preparation derived from Fucus serratus eggs competitively inhibited fertilization. In this paper we report a more complete characterization of these membrane vesicles using enzyme and other assays. The fraction of membranes is enriched in Mg²⁺K⁺ stimulated ATPase, a marker for plant plasma membranes, but has little contamination with enzymes characteristic of endoplasmic reticulum, Golgi apparatus or mitochondria. Though the intact Fucus egg is full of chloroplasts and vesicles containing polysaccharides and polyphenols, there is very low chlorophyll, carbohydrate and polyphenol contamination of the enriched vescle fraction. Overall the results show that the membrane vesicle preparation is highly enriched in plasma membranes.