The pattern of cell wall adhesive formation by Fucus zygotes

Abstract

As a first step in understanding the mechanism of algal adhesion, we describe the adhesive process during early development in Fucus gardneri zygotes. These brown algal embryos adhere to the intertidal substrate shortly after fertilization. Zygotes adhered nonspecifically to hydrophilic and hydrophobic substrates and microspheres. Initial binding of microspheres to the zygote surface coincided with initial zygote adhesion to the substrate. Binding of monodisperse dyed microspheres was used for adhesive localization and quantitation. The timing and extent of adhesive development were variable in populations of synchronously-fertilized zygotes. Small adhesive patches first appeared at 3–6 h, indicating secretion of adhesive components from cytoplasmic vesicles. The zygote hemisphere toward the substrate became sticky by 7–8 h. The entire surface was sticky after rhizoid germination at 12 h. Localization of adhesive at both the outer wall surface and along strands attached to the wall implicates cell wall polymers as a glue component. Loss of microspheres from the rhizoid surface in high salt or chelators indicates that initial adhesive attachment to the wall is noncovalent. Formation of adhesive aggregates in medium showed that the mechanism of adhesive formation includes two separable processes, secretion of adhesive components and extracellular interactions between adhesive components and the wall.