Comparison of concanavalin A and poly-l-lysine as cell adhesives for routine yeast microscopy applications

A frequently encountered problem with imaging budding yeast specimens by light microscopy is that the cells do not adhere well to glass microscope slides. Frustratingly, cells that initially appear stationary in the visual field often become displaced and float away. The development of immunofluorescence microscopy methods for yeast led to the widespread use of poly-l-lysine as an adhesive for cell immobilization. More recently, the lectin-binding protein concanavalin A has also been used as an adhesive that may be less familiar to yeast investigators. Here, we directly compare the ability of poly-l-lysine and concanavalin A to adhere yeast to glass microscope slides using several different assays. Using a simple coating procedure, we find that 1-mg/ml concanavalin A proves superior to various concentrations of poly-l-lysine under all conditions tested and that concanavalin A can be used as an adhesive for live cell imaging without impairing yeast proliferation or cell division kinetics. Importantly, we also delineate forms of sample preparation that are or are not compatible with concanavalin A. Overall, we hope our findings will bring concanavalin A to the attention of a broad spectrum of the yeast community for their microscopy needs.