Investigation of the Adhesion‐Modulating Properties of Bovine Serum Albumin (BSA) in Dictyostelium discoideum

Abstract

Dictyostelium discoideum is a social amoeba commonly used as a model organism in cellular migration studies. Dictyostelium adhesion is mediated by nonspecific interactions, such as Van der Waals forces, as well as specific protein‐mediated interactions between the cell and the substrate. Since adhesive properties of this organism affect its motility, finding ways to manipulate its nonspecific or specific interactions can be useful for future migration experiments. We tested the effects of bovine serum albumin (BSA), which is known to affect nonspecific binding via its interference with electrostatic interactions, on Dictyostelium adhesion. Bacterially‐grown wild‐type cells had increased adhesion when plated on 3% BSA, while axenically‐grown cells exhibited a decrease in adhesion on BSA. To explore why BSA has differential effects on adhesion of Dictyostelium grown under different conditions we tested adhesion of cells lacking one of the specific mediators of attachment, Talin A (TalA). Unlike wild‐type cells, both axenically and bacterially‐grown TalA‐null cells had decreased adhesion on BSA. These data suggest that BSA effects on adhesion may be dependent on TalA in bacterially‐grown cells. Alternatively, since TalA‐null cells have an impaired ability to phagocytose, they may behave more like axenically‐grown cells even when grown on bacteria. In this case, differential effects of BSA may be due to the inherent differences in the adhesion mechanism of cells grown under axenic vs. bacterially‐fed conditions. We are currently examining these possibilities.